Cancer Treatment Reviews

Editors Editorial Board J. Jassem (Poland)
K. Jordan (Germany)
R. A. Stahel S. Aebi (Switzerland) M. Ladetto (Italy)
S. Banerjee (U.K.) F. Lordick (Germany)
Effingerstrasse 40 D. Bedognetti (Qatar) R. J. Mayer (U.S.A.)
CH-3008 Bern J. Bellmunt (Spain) A. Morgans (USA)
Switzerland S. Bielack (Germany) O. Michielin (Switzerland)
J. Bruix (Spain) C. Pezaro (Australia)
G. Curigliano R. Califano (U.K.) M. R. Posner (U.S.A.)
F. Cardoso (Portugal) J. Riess (U.S.A.)
Early Drug Development P. Casali (Italy) C. Sessa (Switzerland)
IEO European Institute of A. Chan (Hong Kong) J. Tabernero (Spain)
R. Coleman (U.K.) K. Tamura (Japan)
Oncology D. De Ruysscher P. Tan (Singapore)
Via Ripamonti, 435 (The Netherlands) M. Weller (Switzerland)
20141 Milan C. Dittrich (Austria) Y. L. Wu (China)
Italy T. Eisen (U.K.)
M. Hutchings (Denmark)
A. Cervantes

University Hospital Valencia
Hematology and Medical Oncology
Blasco Iban˜ez 17
46010 Valencia
Spain

G. Lenz

Universitätsklinikum Münster
Albert-Schweitzer-Campus 1

Gebäude D3
48149 Münster
Germany

Cancer Treatment Reviews 107 (2022) 102406
Contents lists available at ScienceDirect

Cancer Treatment Reviews

journal homepage: www.elsevier.com/locate/ctrv

The gut wall’s potential as a partner for precision oncology in immune
checkpoint treatment

Sara Hone Lopez a, Mathilde Jalving a, Rudolf S.N. Fehrmann a, Wouter B. Nagengast b, Elisabeth
G.E. de Vries a, Jacco J. de Haan a,*

a University of Groningen, University Medical Center Groningen, Department of Medical Oncology, Groningen, the Netherlands
b University of Groningen, University Medical Center Groningen, Department of Gastroenterology and Hepatology, Groningen, the Netherlands

ARTICLE INFO ABSTRACT

Keywords: The gut wall is the largest immune organ and forms a barrier through which gut microbiota interact with the
Immune Checkpoint Inhibitors immune system in the rest of the body. Gut microbiota composition plays a role in the strength and timing of the
Precision Oncology anticancer immune response on immune checkpoint inhibitors (ICI). Surprisingly, the effects of gut wall char­
Gut Wall acteristics, such as physical barrier integrity, permeability, and activity and composition of the intestinal immune
Markers system, on response to ICI has received little attention. Here, we provide an overview of markers to characterize
the gut wall and interventions that can modulate these gut wall characteristics. Finally, we present a future
perspective on how these gut wall markers and interventions might be utilized and studied to improve ICI
treatment strategies.

Introduction investigating whether modulation of gut microbiota through fecal mi­
crobial transplantation (FMT), probiotics, and specific diets can enhance
Tumor cells escape destruction by the immune system by exploiting tumor response to ICI. [8,9]
mechanisms that suppress an anticancer immune response. [1] An
important mechanism is the activation of immune checkpoints, which The gut microbiota interacts with the immune system in the rest of
are the ‘brakes’ in the immune system that prevent inappropriate the body through the gut wall, which encompasses the intestinal mucosa
cytotoxic T-cell activation. Immune checkpoint inhibitors (ICI) can and submucosa, in which immune cells are located which reflect the
release these immune brakes and thus trigger a durable anticancer im­ physical gut barrier. The gut is the primary site of interaction between
mune response. These medicines have dramatically improved patient the host and the outside world and harbors over 70% of the body’s
outcomes across numerous tumor types. [2] Unfortunately, most pa­ immune cells. [10] Surprisingly, the relationship between ICI response,
tients with cancer still do not benefit from ICI as they fail to obtain a integrity, and permeability of the physical gut barrier and the activity of
durable response. [3] the intestinal immune system has been largely overlooked. So far, we
know that the intestinal immune system becomes activated during ICI
A complex set of tumor and patient characteristics is emerging that treatment, and adequate baseline intestinal epithelial cell function, re­
govern the anticancer immune response’s strength and timing. [2,4] flected by high plasma citrulline levels (≥20 μM), is associated with a
Together, these characteristics determine the ’cancer-immune set point’, favorable anticancer immune response to ICI. [11–13] Interventions that
the threshold that must be surpassed in a patient to trigger an anticancer could modulate the integrity, permeability, and immune activity of the
immune response to ICI. [2] The gut microbiota and microbial metab­ gut wall into a more favorable state for response to ICI have the potential
olites can influence the cancer-immune set point. [5–7] Pilot studies to improve disease outcomes in patients. To develop such interventions,
showed that transplantation of fecal microbial samples obtained from we need to understand how gut wall characteristics can impact the
patients responding to ICI into patients not responding to ICI can lead to strength and timing of the anticancer immune response to ICI.
tumor response in initially non-responding patients after reintroduction Furthermore, this understanding might also provide us with tools to
of ICI. [8] This has sparked a series of clinical trials currently better predict response to ICI.

* Corresponding author at: Department of Medical Oncology, PO Box 30.001, 9700 RB Groningen, The Netherlands.
E-mail addresses: [email protected] (S. Hone Lopez), [email protected] (M. Jalving), [email protected] (R.S.N. Fehrmann), [email protected]

(W.B. Nagengast), [email protected] (E.G.E. de Vries), [email protected] (J.J. de Haan).

https://doi.org/10.1016/j.ctrv.2022.102406
Received 22 March 2022; Received in revised form 29 April 2022; Accepted 1 May 2022
Available online 9 May 2022
0305-7372/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

Here, we provide an overview of markers that can be used to char­ Characterizing the integrity and permeability of the physical gut barrier
acterize the integrity, permeability, and immune activity of the gut wall.
We also review interventions that can modulate these gut wall charac­ Physical gut barrier integrity and permeability can be measured non-
teristics. Finally, we present a future perspective on how these gut wall invasively using sugar absorption tests, the most common of which is the
characterization markers and interventions might improve ICI treatment lactulose-to-mannitol (L:M) ratio. Under physiological conditions, an
strategies. intact physical gut barrier preferentially facilitates absorption of
mannitol over lactulose, resulting in a low L:M urinary ratio. When the
Search strategy and selection criteria physical gut barrier becomes disrupted and more permeable, absorption
of lactulose increases, resulting in an increased L:M ratio. Differences in
We retrieved articles from PubMed published up to February 2022 methodologies across laboratories hamper the standardization and
reporting results for relevant markers and interventions. Search terms comparison of studies using L:M ratios. [15,36,37]
are provided in Suppl. Table 1. Only articles published in English, Q1,
and Q2 journals, with full-text availability, and concerning human Blood-based alternatives such as intestinal fatty acid-binding protein
subjects were considered eligible. Next, titles, abstracts, and full text (i-FABP) and citrulline can also be used to characterize physical gut
were sequentially assessed to remove non-relevant articles. Articles barrier integrity and permeability. i-FABP is a water-soluble cytosolic
reporting gastrointestinal malignancy markers or disease-specific protein expressed by mature enterocytes. When intestinal mucosal
markers, conference abstracts, commentaries, editorial correspon­ damage occurs, i-FABP is released into the circulation. [16,38,39]
dence, or pre-clinical studies were excluded. If multiple studies address Citrulline is an amino acid produced by small bowel enterocytes from
the same marker, we selected the article(s) that reported results with the glutamine and derived amino acids Decreased plasma citrulline reflects
highest level of evidence as defined by the Oxford 2011 Levels of Evi­ reduced enterocyte mass and function. [17,40]
dence, v2.1. To identify articles missed by our search strategy, we
screened the references of the remaining articles for additional relevant Ex-vivo assessment of physical gut barrier integrity and permeability
studies. The final selection of references included for each marker and is possible through immunohistochemical staining of tight junctions and
intervention are provided in Suppl. Tables 2–5. zonula adherens components. [18] Physical gut barrier integrity can
also be assessed ex-vivo by measuring transepithelial electrical resis­
Characterizing gut wall integrity, permeability, and immune tance with Ussing chambers. [19]
activity
In-vivo physical gut barrier integrity assessment is possible using
The gut, formed by the small and large intestine, is selectively probe- or endoscope-based confocal laser endomicroscopy. Confocal
permeable. While protection from potentially noxious luminal contents laser endomicroscopy can visualize leakage of lanthanum nitrate into
by the gut wall is essential, low-grade exposure of the body to the gut’s the paracellular space. This leakage is, which is associated with tight
contents builds and maintains an adequate immune defense. [14] Two junction and zonula adherens loss. [18] Confocal laser endomicroscopy,
components of the gut wall are vital to preserving intestinal homeosta­ combined with intravenous fluorescein administration, allows grading
sis: the physical gut barrier and the intestinal immune system. of physical barrier integrity and permeability using the Confocal Leak
Score. The Confocal Leak Score measures fluorescein leakage from the
We identified markers that characterize the integrity and perme­ submucosa into the gut lumen through epithelial breaks. The Confocal
ability of the physical gut barrier (n = 11, Table 1) and the activity of the Leak Score has been validated and is predictive for diarrhea motions per
intestinal immune system (n = 10, Table 2). day in inflammatory bowel disease (IBD). [20] In-vivo and ex-vivo tissue
analyses may be cumbersome for patients. Still, in the case of in-vivo
analysis, they offer a level of real-time diagnostic accuracy that is not
obtainable otherwise.

Table 1 Specimen Cut-off Sens/Spec Context LoE Ref.
Physical gut wall markers. Urine > 0.03 (%) 2 [15]
Asymptomatic first-degree relatives of individuals
Marker NR with Crohn’s disease

Lactulose:
Mannitol

i-FABP Plasma & Serum 382 pg/mL 80/87 Celiac disease vs normal 2 [16]
Citrulline Plasma & Serum 20 µmol/L 80/84 Enteropathies* vs normal 2 [17]
TJ proteins Biopsy NR NR Intestinal ischemia–reperfusion 3 [18]
Transepithelial electrical resistance Biopsy NR NR Functional dyspepsia vs normal 3 [19]
TJ and ZA function with lanthanum nitrate Biopsy NR NR Intestinal ischemia–reperfusion 3 [18]

electron microscopy eCLE ileal images Confocal leak 95/98 Symptomatic IBD vs asymptomatic IBD vs normal 2 [20]
Confocal leak score score
pCLE duodenal >13 79/88 Functional dyspepsia vs normal 2 [19]
Epithelial gap density images > 15 gaps / 1000 NR
Urine cells NR IBS vs normal 3 [21]
51Cr-EDTA Plasma & Urine NR Comparison of patients with acute gastrointestinal 3 [22]
D-lactate NR injury grade I-IV
Children with no, mild, moderate, or severe 3 [23]
Carotenoids Serum NR NR malnutrition

*Celiac disease, tropical enteropathy, Crohn’s disease, mucositis, acute rejection in intestinal transplantation.
51Cr-EDTA, Chromium-51 ethylenediaminetetraacetic acid; D-lactate, D-lactate dehydrogenase; eCLE, endoscope-based confocal laser endomicroscopy; IBD, in­
flammatory bowel disease; IBS, irritable bowel syndrome; i-FABP, intestinal fatty acid-binding protein; LoE, Level of Evidence (as defined by Oxford 2011 Levels of
Evidence, v2.1.); NR, not reported; pCLE, probe-based confocal laser endomicroscopy; Sens, sensitivity; Spec, specificity; TJ, tight junction; ZA, zonula adherens.

2

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

Table 2 primarily by enterocytes but also by macrophages, monocytes, and
Source articles of intestinal immune system markers. granulocytes in response to proinflammatory stimuli. Lipocalin-2 can
detect low-grade inflammation and is equivalent to fecal calprotectin in
Marker Specimen Cut- Sens/ Context LoE Ref. IBD. [26,41] Glycoprotein CHI3L is highly expressed in colon epithelial
off Spec cells and lamina propria macrophages at sites of mucosal inflammation.
(%) Fecal CHI3L levels correlate with clinical and endoscopic IBD activity.
[27]
Lactoferrin Feces >7.25 82/79 IBD vs 1 [24]
µg/g controls (IBS 1 [24] Detailed characterization of immune cell infiltrates is possible
Calprotectin Feces >50 88/73 and normal) 2 [25] through ex-vivo assessment of biopsies using immunohistochemical
µg/g IBD vs stainings, flow cytometry, or quantitative real-time polymerase chain
S100A12 Feces >0.8 100/ controls (IBS 2 [26] reaction. Thus, immune cell populations can be quantified and charac­
µg/g 81 and normal) 2 [27] terized, and their infiltration patterns analyzed [21–31,41–43]. Biopsies
Lipocalin-2 Feces 100/ Crohn’s 3 [28] are considered the gold standard to diagnose and monitor intestinal
0.81 91 disease vs inflammation. However, biopsies they face the limitation that they
CHI3L1 Feces µg/g 86/96 normal [29] represent a small tissue area and therefore may not be representative.
Biopsy 95// Ulcerative [30]
Immune cells >13.7 96 colitis vs [31] Interventions modulating the integrity, permeability, and
IE CD3 + T ng/g normal immune activity of the gut wall
NR 85/89 IBS vs
cells, LP NR normal Modulation of the integrity, permeability, and immune activity of
CD45 + cells NR IBD vs the gut wall is possible through pharmaceutical intervention, diet and
and NR controls supplements, pre- and pro-biotics, and FMT. We identified 11 pharma­
eosinophils NR (IEC, IBS or ceutical interventions, one dietary intervention, and three microbiota-
Macrophages normal) directed interventions (Table 3).
NR IBD vs
MAIT cells normal Pharmaceutical interventions

Celiac Clinically approved treatments that non-selectively promote gut
disease vs mucosal healing through immunomodulation are Janus kinase (JAK)
NCGWS vs inhibitors, tumor necrosis factor-α (TNF-α) inhibitors, corticosteroids,
non-NCGWS cyclosporine, ustekinumab, and thiopurines. In addition, selective
modulation of the intestinal immune system is possible with 5-aminosa­
NR IBD vs 3 licylic acid and vedolizumab. [44–52,61–65]

normal Next to these clinically used gut wall modulators, larazotide acetate
and propionyl-L-carnitine increase physical gut wall integrity and
Ulcerative 3 decrease intestinal permeability, colonic-release low-molecular-weight
heparin promotes mucosal healing and reduces inflammation, and der­
NR colitis vs salazine sodium modulates intestinal immune system activity. [53–56]

normal Dietary interventions

CD4 + CD25+ Ulcerative 3 Improvement of integrity, permeability, and immune activity of the
FoxP3 + cells gut wall with diets has been explored in a broad range of gastrointestinal
colitis vs conditions. While consensus on dietary interventions targeting gut wall
function remains to be reached, certain dietary patterns are considered
normal to be noxious or protective. High consumption of sugar, animal protein,
and saturated fats is associated with gut microbiota dysbiosis, intestinal
PMN-elastase Feces >19 84/87 IBD vs IBS 2 [32] inflammation, and increased risk for IBD. High fiber consumption has
been associated with more favorable and varied gut microbiota
DPP4 Feces ng/g composition and increased short-chain fatty acid (SCFA) production,
HMGB1 Feces thus promoting gut wall homeostasis. [66–68]
NR NR IBD 2 [33]
UMH Urine We identified one dietary intervention directed at the gut wall: oral
NR NR IBD vs 3 [34] glutamine supplementation. Glutamine is a major energy source for
enterocytes. Without glutamine, enterocytes decay, causing physical gut
normal barrier disruption and increased permeability. Oral supplementation of
glutamine normalizes intestinal permeability in patients with post­
NR NR IBD vs 3 [35] infectious diarrhea-predominant IBS. [57]

normal Interventions with prebiotics, probiotics, and gut microbiota

CHI3L1, Chitinase 3-like-1; DPP4, Dipeptidyl Peptidase-4; HMGB1, high The use of pre- and probiotics to reinstate gut wall homeostasis
mobility group box 1; IBD, inflammatory bowel disease; IBS, irritable bowel shows promising results in experimental settings. Prebiotics are non-
syndrome; IE, intra-epithelial; IEC, Infectious enterocolitis; LoE, Level of Evi­ digestible compounds that are metabolized by gut microbiota. Pre­
dence (evidence as defined by the Oxford 2011 Levels of Evidence, v2.1.); LP, biotics promote favorable gut microbiota composition and/or activity,
lamina propria; MAIT, mucosal-associated invariant T cells; NCGWS; non- resulting in beneficial physiological effects on the host. [58] Suppletion
coeliac gluten/wheat sensitivity; NR, not reported; PMN, polymorphonuclear with prebiotic inulin-type-ϐ fructans suppletion is beneficial for some
neutrophil; S100A12, S100 calcium-binding protein A12; Sens, sensitivity; Spec,
specificity; UMH, urinary excretion of n-methylhistamine.

Characterizing the activity of the intestinal immune system

Calprotectin and lactoferrin are the most commonly used markers of
intestinal immune activation. Calprotectin is the predominant cytosolic
protein in neutrophils, while lactoferrin is a protein in neutrophil sec­
ondary granules. Their elevation in feces can reflect microscopic and
macroscopic intestinal inflammation. Calprotectin can serve to predict
and monitor IBD flare-ups and distinguish IBD from non-inflammatory
intestinal conditions. [24,41,42] Variations in calprotectin and lacto­
ferrin levels across age groups have been reported, therefore age-
adjusted cut-off values for both markers have been proposed. [43]

Fecal markers S100 calcium-binding protein A12 (S100A12),
lipocalin-2, and Chitinase 3-like-1 (CHI3L) are not yet clinically vali­
dated alternatives to detect bowel inflammation. S100A12, like cal­
protectin, is a cytoplasmic neutrophil-derived protein released upon
neutrophil activation. [25] Lipocalin-2 is a glycoprotein with immuno­
modulatory and antimicrobial effects secreted into the gut lumen

3

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

Table 3
Source articles of gut wall directed interventions.

Intervention Mechanism of action Gut- Effect Context LoE Ref.
selective? Anti-inflammatory and mucosal healing IBD 1 [44]
Corticosteroids Interact with glucocorticoid receptors in cell nuclei IBD 1 [45]
Promote tolerogenic over immunogenic phenotype, No
Integrin neutralize proinflammatory cytokines
inhibitor Not fully understood Yes Anti-inflammatory and mucosal healing
Vedolizumab blocks α4β7 integrin on T and B cells

Thiopurines Inhibit nucleotide and purine synthesis, reducing the No Anti-inflammatory, mucosal healing Crohn’s disease 1 [46]
proliferation of rapidly dividing cells
Cyclosporine Block gene activation of effector T cells, downregulate No Anti-inflammatory and mucosal healing Ulcerative colitis 1 [47]
JAK-inhibitors their cytotoxic activity and reduce B cell infiltration in No Anti-inflammatory and mucosal healing IBD 1 [48]
the gut mucosa
5-ASA Calcineurin inhibitor Yes Anti-inflammatory and mucosal healing IBD 2 [49]
Ustekinumab Selectively inhibit JAK-1 and JAK-2, thus No Crohn’s disease 2 [50]
TNF-α inhibitors downmodulating signaling of pro-inflammatory No Anti-inflammatory and mucosal healing Ulcerative colitis 2 [51]
cytokines of IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 Crohn’s disease 2 [52]
Not fully understood Anti-inflammatory, mucosal healing Ulcerative colitis. 2 [52,53]
Metabolized by IECs, local effect
Inhibits the T-helper 1 and 17 pathways by blocking Improve physical gut barrier function and
the p40 subunit of IL-12 & IL-23 decrease permeability
Inhibit the proinflammatory activity of the cytokine Anti-inflammatory and mucosal healing
TNF-α

Dersalazine Decreases expression of inflammatory genes and Yes Mucosal healing Ulcerative colitis, 2 [54]
sodium proinflammatory cytokines in colonic tissue through Yes as co-treatment [55]
anti-platelet activating factor activity Yes [56]
Propionyl-L- Source of l-carnitine and propionyl-coenzyme-A for No Increases physical gut barrier integrity and Coeliac’s disease 2
carnitine colonocytes, proposed to in this way facilitate energy No decreases intestinal permeability
release No
Lazarotide Peptide derived from zonula occludens toxin, Anti-inflammatory Ulcerative colitis 2
acetate modulator of tight-junctions and inhibitor of
paracellular permeability Decreases intestinal permeability Post-infectious 3 [57]
LMWH Not fully understood IBS-D 1 [58]
Thought to modulate complement pathways and Anti-inflammatory, functional changes gut IBD 1 [59]
Oral glutamine proinflammatory cytokines microbiota
Not fully understood Mucosal healing, improve physical gut IBD, IBS, 1 [60]
Prebiotics Glutamine is a major source of energy for enterocytes barrier integrity, decrease intestinal C. difficile, SIBO
Not fully understood permeability, anti-inflammatory
Probiotics Mucosal healing, anti-inflammatory, Ulcerative colitis
Not fully understood No eubiosis?

FMT Not fully understood No

5-ASAs, mesalamine or 5-aminosalicylic acid; FMT, fecal microbial transplant; IBD, inflammatory bowel disease; IBS-D, diarrhea-predominant irritable bowel syn­

drome; IL, interleukin; JAK, Janus kinase; LMWH, low-molecular weight heparin; LoE, Level of Evidence (evidence as defined by the Oxford 2011 Levels of Evidence,
v2.1.); SIBO, small intestinal bacterial overgrowth; TNF-α, tumor necrosis factor alpha.

patients with ulcerative colitis. It reduces inflammation, promotes upregulated rhamnose synthesis and an increase of the SCFA propionate
mucosal healing, and induces functional and compositional microbiota production. [72] Manipulation of the gut microbiota through FMT has
changes. [59] Probiotics are live microorganisms that can be beneficial been explored in the context of severe reduction in microbial diversity
to the host’s health. Probiotics exert their effects by promoting a caused by pathogens like C. difficile and as an experimental treatment in
favorable gut microbiota composition and functionality, improving IBD. In patients with C. difficile, FMT induced remission and symptom­
physical gut barrier function, immunomodulation and modulating atic relief. [73] In patients with ulcerative colitis, FMT increased di­
physiological processes on the host. [69] In diarrhea-predominant IBS, versity, induced remission, and mucosal healing. FMT did not lead to
lactic acid bacteria supplementation improves mucosal barrier function. objective changes in inflammatory markers like calprotectin. [60,74]
[70] When added to the conventional treatment of patients with mild to The exact effects of FMT are unknown. It is hypothesized that FMT
moderate ulcerative colitis, probiotic mix VSL#3 can boost mucosal promotes recolonization of bacteria with properties beneficial for
healing and increase endoscopic remission rates. [71] While studies health, and thus an optimal balance of microbiota in the gastrointestinal
suggest that use of prebiotic and probiotics may be beneficial in certain tract. While the short-term effects of FMT are promising, several aspects
clinical settings like IBD, the variation in formulations and dosages used, remain unclear. Ongoing studies will provide more data on the effect of
as well as the limited data available from controlled trials, preclude FMT on objective endpoints such as mucosal healing or disease extent.
deriving firm conclusions on their effects and efficacy. [58] Importantly, Further research is required to address the impact of bowel preparation
data suggest that probiotic supplementation may also enhance the on FMT effectiveness, to determine the best administration route and
therapeutic effects of ICI therapy. Supplementation with CMBM588, a dosage of FMT as well as to define the long-term effects of FMT on the
probiotic containing Clostridium butyricum which produces the SCFA recipient. [60,73]
butyrate appears to improve progression-free survival in patients with
metastatic renal cell cancer receiving dual ICI therapy. Patients
receiving CBM588 showed changes in gut microbiota functionality, like

4

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

Gut wall integrity, permeability, and immune activity in the and gut microbiota, as well as tumor and patient characteristics should
context of ICI treatment be taken into account. Determining PD-1 and CTLA-4 expression of cells
in the gut wall may also be of interest, since these ICI targets have a role
To date, efforts have focused on the relationship between gut lumen in maintaining intestinal immune system homeostasis. [87,88] If data
microbiota composition and the strength of the anticancer immune suggest a role for the gut wall in the response to ICI, and specific gut wall
response induced by ICI. In addition, an association between gut mucosa phenotypes are associated with response to ICI, interventions to promote
microbial composition and response to ICI and to gastrointestinal such beneficial phenotypes should be considered.
immune-related adverse events was recently shown. [75] In initial ICI
non-responders, FMT, and re-introduction of ICI can lead to tumor Together, the data obtained from exploring the role of the gut wall in
response. [8] However, there is no consensus on which bacterial species tumor response to ICI might lead to novel markers and therapeutic
are favorable. [8,76] Promising data suggest that supplementation with targets with which to predict and potentiate the response to ICI.
probiotics may improve clinical outcomes of patients receiving dual ICI
therapy. [72] Funding

It is becoming increasingly evident that microbial functionality may This research did not receive any specific grant from funding
be equally relevant or even more relevant than gut microbiota compo­ agencies in the public, commercial, or not-for-profit sectors.
sition itself. Shotgun metagenomic sequencing was performed on pre-
ICI-treatment stool samples collected in 5 observational cohorts Author contribution
recruiting ICI-naive patients with advanced cutaneous melanoma (n =
165). It showed that the gut microbiome has a relevant but cohort- All authors contributed to manuscript conception, drafting of the
dependent association with response to ICI. [77] We are currently manuscript, provided critical review and revisions, and approved the
generating metabolomics data and will measure markers discussed in final version of the manuscript.
this review to characterize the gut wall in the abovementioned cohorts
of ICI-naïve patients. CRediT authorship contribution statement

SCFAs have been associated with response to ICI. SCFAs are micro­ Sara Hone Lopez: Conceptualization, Methodology, Formal anal­
bial metabolites produced by microbial fermentation of dietary fibers. ysis, Investigation, Writing – original draft, Writing – review & editing,
SCFAs interact with the gut wall, contribute to intestinal immune ho­ Visualization. Mathilde Jalving: Conceptualization, Methodology,
meostasis and intestinal epithelial barrier integrity. Patients with non- Writing – review & editing, Supervision. Rudolf S.N. Fehrmann:
small cell lung cancer (NSCLC) responding to programmed cell death Conceptualization, Methodology, Writing – review & editing. Wouter B.
protein 1 (PD-1) antibody therapy had a higher baseline fecal SCFAs Nagengast: Conceptualization, Writing – review & editing. Elisabeth
concentration. [78] In line with this, in patients with a wide range of G.E. de Vries: Conceptualization, Methodology, Writing – review &
malignancies treated with PD-1 antibodies, high baseline fecal concen­ editing. Jacco J. de Haan: Conceptualization, Methodology, Writing –
trations of SCFAs propionic, butyric, valeric, and acetic acid and high original draft, Writing – review & editing, Supervision.
plasma levels of isovaleric acid were associated with longer progression-
free survival. [79] Furthermore, in patients with NSCLC, SCFAs were Declaration of Competing Interest
shown to be the main metabolites produced by the gut microbiota of
long-term responders to PD-1 antibody therapy. [80] In contrast, low The authors declare that they have no known competing financial
baseline serum propionic and butyric acid were associated with longer interests or personal relationships that could have appeared to influence
progression-free survival in patients with metastatic melanoma and the work reported in this paper.
metastatic prostate cancer receiving cytotoxic T-lymphocyte-associated
protein 4 (CTLA-4) antibodies. [81] Due to differences in the method­ Appendix A. Supplementary material
ologies applied and modest size of patient populations included, no clear
conclusions can be drawn from the divergent results across the above­ Supplementary data to this article can be found online at https://doi.
mentioned studies. Adequate enterocyte function, reflected by high org/10.1016/j.ctrv.2022.102406.
plasma citrulline levels (≥20 μM) at baseline, correlated with favorable
response to ICI, longer progression-free, and overall survival in patients References
with advanced NSCLC receiving anti-PD-1 therapy. [13] The effects of
ICI therapy on the intestinal immune system have been investigated in [1] Hanahan D. Hallmarks of cancer: new dimensions. Cancer Discov 2022;12:31–46.
more detail in the context of ICI-induced colitis. In ICI-induced colitis, https://doi.org/10.1158/2159-8290.CD-21-1059.
fecal calprotectin and lactoferrin levels are elevated. [11,82–84] ICI-
induced colitis is characterized by a heavy CD8 + T cell mucosal infil­ [2] Chen DS, Mellman I. Elements of cancer immunity and the cancer–immune set
trate. [12,85] In the ongoing DEFENCE study, colon biopsies and blood point. Nature 2017;541:321–30. https://doi.org/10.1038/nature21349.
samples are obtained at baseline and during ICI treatment to determine
the effects of ICI on the physical gut wall and the intestinal immune [3] Haslam A, Prasad V. Estimation of the percentage of US patients with cancer who
system activation in relation to ICI tumor response. [86] are eligible for and respond to checkpoint inhibitor immunotherapy drugs. JAMA
Netw Open 2019;2(5):e192535. https://doi.org/10.1001/
Future perspective: Exploiting the gut wall to predict and jamanetworkopen.2019.2535.
potentiate tumor response to ICI
[4] Blank CU, Haanen JB, Ribas A, Schumacher TN. Cancer immunology. The “cancer
Compelling data suggest that gut microbiota composition and func­ immunogram”. Science 2016;352:658–60. https://doi.org/10.1126/science.
tionality are relevant to tumor response to ICI. This raises the question of aaf2834.
whether this may also be the case for the gut wall. To study this hy­
pothesis, the gut wall phenotypes of responders and non-responders to [5] Frankel AE, Coughlin LA, Kim J, Froehlich TW, Xie Y, Frenkel EP, et al.
ICI should be defined and compared. This can be done by measuring Metagenomic shotgun sequencing and unbiased metabolomic profiling identify
physical gut barrier integrity, intestinal permeability, and intestinal specific human gut microbiota and metabolites associated with immune checkpoint
inflammation markers at baseline and during ICI treatment. In addition, therapy efficacy in melanoma patients. Neoplasia 2017;19(10):848–55. https://
the interplay between gut wall immune composition and activity status doi.org/10.1016/j.neo.2017.08.004.

[6] Mager LF, Burkhard R, Pett N, Cooke NCA, Brown K, Ramay H, et al. Microbiome-
derived inosine modulates response to checkpoint inhibitor immunotherapy.
Science 2020;369(6510):1481–9. https://doi.org/10.1126/science.abc3421.

[7] Smith M, Dai A, Ghilardi G, Amelsberg KV, Devlin SM, Pajarillo R, et al. Gut
microbiome correlates of response and toxicity following anti-CD19 CAR T cell
therapy. Nat Med 2022;28(4):713–23. https://doi.org/10.1038/s41591-022-
01702-9.

[8] Baruch EN, Youngster I, Ben-Betzalel G, Ortenberg R, Lahat A, Katz L, et al. Fecal
microbiota transplant promotes response in immunotherapy-refractory melanoma

5

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

patients. Science 2021;371(6529):602–9. https://doi.org/10.1126/science. with active ulcerative colitis and increase with disease activity. Inflamm Bowel Dis
abb5920. 2006;12(6):447–56. https://doi.org/10.1097/00054725-200606000-00003.
[9] McQuade JL, Daniel CR, Helmink BA, Wargo JA. Modulating the microbiome to [32] Langhorst J, Elsenbruch S, Koelzer J, Rueffer A, Michalsen A, Dobos JB.
improve therapeutic response in cancer. Lancet Oncol 2019;20:e77–91. https:// Noninvasive markers in the assessment of intestinal inflammation in inflammatory
doi.org/10.1016/S1470-2045(18)30952-5. bowel diseases: performance of fecal lactoferrin, calprotectin, and PMN-Elastase,
[10] Vighi G, Marcucci F, Sensi L, Di Cara G, Frati F. Allergy and the gastrointestinal CRP, and clinical indices. Am J Gastroenterol 2008;103:162–9. https://doi.org/
system. Clin Exp Immunol 2008;153(Suppl 1):3–6. https://doi.org/10.1111/ 10.1111/j.1572-0241.2007.01556.x.
j.1365-2249.2008.03713.x. [33] Pinto-Lopes P, Melo F, Afonso J, Pinto-Lopes R, Rocha C, Melo D, et al. Fecal
[11] Berman D, Parker SM, Siegel J, et al. Blockade of cytotoxic T-lymphocyte antigen-4 Dipeptidyl Peptidase-4: An emergent biomarker in inflammatory bowel disease.
by ipilimumab results in dysregulation of gastrointestinal immunity in patients Clin Transl Gastroenterol 2021;12(3):e00320. https://doi.org/10.14309/
with advanced melanoma. Cancer Immun 2010;10:11. ctg.0000000000000320.
[12] Luoma AM, Suo S, Williams HL, Sharova T, Sullivan K, Manos M, et al. Molecular [34] Palone F, Vitali R, Cucchiara S, Mennini M, Armuzzi A, Pugliese D, et al. Fecal
pathways of colon inflammation induced by cancer immunotherapy. Cell 2020;182 HMGB1 Reveals microscopic inflammation in adult and pediatric patients with
(3):655–671.e22. https://doi.org/10.1016/j.cell.2020.06.001. inflammatory bowel disease in clinical and endoscopic remission. Inflamm Bowel
[13] Ouaknine Krief J, Helly de Tauriers P, Dumenil C, Neveux N, Dumoulin J, Dis 2016;22(12):2886–93. https://doi.org/10.1097/MIB.0000000000000938.
Giraud V, et al. Role of antibiotic use, plasma citrulline and blood microbiome in [35] Winterkamp S, Weidenhiller M, Otte P, Stolper J, Schwab D, Hahn EG, et al.
advanced non-small cell lung cancer patients treated with nivolumab. Urinary excretion of N-methylhistamine as a marker of disease activity in
J Immunother Cancer 2019;7(1). https://doi.org/10.1186/s40425-019-0658-1. inflammatory bowel disease. Am J Gastroenterol 2002;97(12):3071–7. https://doi.
[14] Agace WW, McCoy KD. Regionalized development and maintenance of the org/10.1111/j.1572-0241.2002.07028.x.
intestinal adaptive immune landscape. Immunity 2017;46:532–48. https://doi. [36] Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in
org/10.1016/j.immuni.2017.04.004. humans. Gut 2019;68:1516–26. https://doi.org/10.1136/gutjnl-2019-318427.
[15] Turpin W, Lee S-H, Raygoza Garay JA, Madsen KL, Meddings JB, Bedrani L, et al. [37] Seethaler B, Basrai M, Neyrinck AM, Nazare J-A, Walter J, Delzenne NM, et al.
Increased intestinal permeability is associated with later development of Crohn’s Biomarkers for assessment of intestinal permeability in clinical practice. Am J
disease. Gastroenterology 2020;159(6):2092–2100.e5. https://doi.org/10.1053/j. Physiol Gastrointest Liver Physiol 2021;321(1):G11–7. https://doi.org/10.1152/
gastro.2020.08.005. ajpgi.00113.2021.
[16] Adriaanse MPM, Tack GJ, Passos VL, Damoiseaux JGMC, Schreurs MWJ, van [38] Bischoff SC, Barbara G, Buurman W, Ockhuizen T, Schulzke J-D, Serino M, et al.
Wijck K, et al. Serum I-FABP as marker for enterocyte damage in coeliac disease Intestinal permeability–a new target for disease prevention and therapy. BMC
and its relation to villous atrophy and circulating autoantibodies. Aliment Gastroenterol 2014;14(1). https://doi.org/10.1186/s12876-014-0189-7.
Pharmacol Ther 2013;37(4):482–90. https://doi.org/10.1111/apt.12194. [39] Derikx JPM, Vreugdenhil ACE, Van den Neucker AM, Grootjans J, van Bijnen AA,
[17] Fragkos KC, Forbes A. Citrulline as a marker of intestinal function and absorption Damoiseaux JGMC, et al. A pilot study on the noninvasive evaluation of intestinal
in clinical settings: A systematic review and meta-analysis. United European damage in celiac disease using I-FABP and L-FABP. J Clin Gastroenterol 2009;43
Gastroenterol J 2018;6:181–91. https://doi.org/10.1177/2050640617737632. (8):727–33. https://doi.org/10.1097/MCG.0b013e31819194b0.
[18] Schellekens DH, Hundscheid IHR, Leenarts CA, Grootjans J, Lenaerts K, [40] Hueso T, Gauthier J, Joncquel Chevalier-Curt M, Magro L, Coiteux V, Dulery R,
Buurman WA, et al. Human small intestine is capable of restoring barrier function et al. Association between low plasma level of citrulline before allogeneic
after short ischemic periods. World J Gastroenterol 2017;23(48):8452–64. https:// hematopoietic cell transplantation and severe gastrointestinal graft vs host disease.
doi.org/10.3748/wjg.v23.i48.8452. Clin Gastroenterol Hepatol 2018;16(6):908–917.e2. https://doi.org/10.1016/j.
[19] Nojkov B, Zhou S-Y, Dolan RD, Davis EM, Appelman HD, Guo X, et al. Evidence of cgh.2017.12.024.
duodenal epithelial barrier impairment and increased pyroptosis in patients with [41] Jukic A, Bakiri L, Wagner EF, Tilg H, Adolph TE. Calprotectin: from biomarker to
functional dyspepsia on confocal laser endomicroscopy and “ex vivo” mucosa biological function. Gut 2021;70:1978–88. https://doi.org/10.1136/gutjnl-2021-
analysis. Am J Gastroenterol 2020;115(11):1891–901. https://doi.org/10.14309/ 324855.
ajg.0000000000000827. [42] Zollner A, Schmiderer A, Reider SJ, et al. Faecal biomarkers in inflammatory bowel
[20] Chang J, Leong RW, Wasinger VC, Ip M, Yang M, Phan TG. Impaired intestinal diseases: calprotectin versus lipocalin-2—a comparative study. J Crohn Colitis.
permeability contributes to ongoing bowel symptoms in patients with 2021;15;43-35. doi: 10.1093/ecco-jcc/jjaa124.
inflammatory bowel disease and mucosal healing. Gastroenterology 2017;153(3): [43] Joshi S, Lewis SJ, Creanor S, Ayling RM. Age-related faecal calprotectin, lactoferrin
723–731.e1. https://doi.org/10.1053/j.gastro.2017.05.056. and tumour M2-PK concentrations in healthy volunteers. Ann Clin Biochem 2010;
[21] Dunlop SP, Hebden J, Campbell E, Naesdal J, Olbe L, Perkins AC, et al. Abnormal 47:259–63. https://doi.org/10.1258/acb.2009.009061.
intestinal permeability in subgroups of diarrhea-predominant irritable bowel [44] Pola S, Patel D, Ramamoorthy S, McLemore E, Fahmy M, Rivera–Nieves J, et al.
syndromes. Am J Gastroenterol 2006;101(6):1288–94. Strategies for the care of adults hospitalized for active ulcerative colitis. Clin
[22] Li H, Chen Y, Huo F, Wang Y, Zhang D. Association between acute gastrointestinal Gastroenterol Hepatol 2012;10(12):1315–1325.e4.
injury and biomarkers of intestinal barrier function in critically ill patients. BMC [45] Schreiber S, Dignass A, Peyrin-Biroulet L, Hather G, Demuth D, Mosli M, et al.
Gastroenterol 2017;17:45. https://doi.org/10.1186/s12876-017-0603-z. Systematic review with meta-analysis: real-world effectiveness and safety of
[23] Vieira MM, Paik J, Blaner WS, Soares AM, Mota RMS, Guerrant RL, et al. vedolizumab in patients with inflammatory bowel disease. J Gastroenterol 2018;53
Carotenoids, retinol, and intestinal barrier function in children from northeastern (9):1048–64. https://doi.org/10.1007/s00535-018-1480-0.
Brazil. J Pediatr Gastroenterol Nutr 2008;47(5):652–9. https://doi.org/10.1097/ [46] Chatu S, Subramanian V, Saxena S, et al. The role of thiopurines in reducing the
MPG.0b013e31816bf4bf. need for surgical resection in Crohn’s disease: a systematic review and meta-
[24] Mosli MH, Zou G, Garg SK, Feagan SG, MacDonald JK, Chande N, et al. C-reactive analysis. Am J Gastroenterol 2014;109:23–34. https://doi.org/10.1038/
protein, fecal calprotectin, and stool lactoferrin for detection of endoscopic activity ajg.2013.402.
in symptomatic inflammatory bowel disease patients: a systematic review and [47] Van Assche G, D’Haens G, Noman M, et al. Randomized, double-blind comparison
meta-analysis. Am J Gastroenterol 2015;110(6):802–19. https://doi.org/10.1038/ of 4 mg/kg versus 2 mg/kg intravenous cyclosporine in severe ulcerative colitis.
ajg.2015.120. Gastroenterology 2003;125:1025–31. https://doi.org/10.1016/j.cgh.2012.07.006.
[25] Kaiser T, Langhorst J, Wittkowski H, Becker K, Friedrich AW, Rueffer A, et al. [48] Salas A, Hernandez-Rocha C, Duijvestein M, Faubion W, McGovern D, Vermeire S,
Faecal S100A12 as a non-invasive marker distinguishing inflammatory bowel et al. JAK-STAT pathway targeting for the treatment of inflammatory bowel
disease from irritable bowel syndrome. Gut 2007;56(12):1706–13. https://doi.org/ disease. Nat Rev Gastroenterol Hepatol 2020;17(6):323–37. https://doi.org/
10.1136/gut.2006.113431. 10.1038/s41575-020-0273-0.
[26] Thorsvik S, Damås JK, Granlund AvB, Flo TH, Bergh K, Østvik AE, et al. Fecal [49] Ogata H, Yokoyama T, Mizushima S, Hagino A, Hibi T. Comparison of efficacy of
neutrophil gelatinase-associated lipocalin as a biomarker for inflammatory bowel once daily multimatrix mesalazine 2.4 g/day and 4.8 g/day with other 5-amino­
disease. J Gastroenterol Hepatol 2017;32(1):128–35. https://doi.org/10.1111/ salicylic acid preparation in active ulcerative colitis: a randomized, double-blind
jgh.13598. study. Intest Res 2018;16(2):255. https://doi.org/10.5217/ir.2018.16.2.255.
[27] Aomatsu T, Imaeda H, Matsumoto K, Kimura E, Yoden A, Tamai H, et al. Faecal [50] Straatmijer T, Biemans VBC, Hoentjen F, et al. Ustekinumab for Crohn’s Disease:
chitinase 3-like-1: a novel biomarker of disease activity in paediatric inflammatory Two-Year Results of the Initiative on Crohn and Colitis (ICC) Registry, a
bowel disease. Aliment Pharmacol Ther 2011;34(8):941–8. https://doi.org/ Nationwide Prospective Observational Cohort Study. J Crohns Colitis. 2021;15:
10.1111/j.1365-2036.2011.04805.x. 1920-1930. doi: 10.1093/ecco-jcc/jjab081.
[28] Carroccio A, Giannone G, Mansueto P, Soresi M, La Blasca F, Fayer F, et al. [51] H¨am¨ala¨inen A, Sipponen T, Kolho KL. Infliximab in pediatric inflammatory bowel
Duodenal and rectal mucosa inflammation in patients with non-celiac wheat disease rapidly decreases fecal calprotectin levels. World J Gastroenterol 2011;17:
sensitivity. Clin Gastroenterol Hepatol 2019;17(4):682–690.e3. https://doi.org/ 5166–71. https://doi.org/10.3748/wjg.v17.i47.5166.
10.1016/j.cgh.2018.08.043. [52] Noth R, Stüber E, H¨asler R, Nikolaus S, Kühbacher T, Hampe J, et al. Anti-TNF-α
[29] Perminow G, Reikvam DH, Lyckander LG, Brandtzaeg P, Vatn MH, Carlsen HS. antibodies improve intestinal barrier function in Crohn’s disease. J Crohns Colitis
Increased number and activation of colonic macrophages in pediatric patients with 2012;6(4):464–9. https://doi.org/10.1016/j.crohns.2011.10.004.
untreated Crohn’s disease. Inflamm Bowel Dis 2009;15:1368–78. https://doi.org/ [53] Pontes C, Vives R, Torres F, Pan´es J. Safety and activity of dersalazine sodium in
10.1002/ibd.20916. patients with mild-to-moderate active colitis: double-blind randomised proof of
[30] Haga K, Chiba A, Shibuya T, Osada T, Ishikawa D, Kodani T, et al. MAIT cells are concept study. Inflamm Bowel Dis 2014;20:2004–12. https://doi.org/10.1097/
activated and accumulated in the inflamed mucosa of ulcerative colitis. MIB.0000000000000166.
J Gastroenterol Hepatol 2016;31(5):965–72. https://doi.org/10.1111/jgh.13242. [54] Mikhailova TL, Sishkova E, Poniewierka E, Zhidkov KP, Bakulin IG, Kupcinskas L,
[31] Holm´en N, Lundgren A, Lundin S, Bergin A-M, Rudin A, Sjo¨vall H, et al. Functional et al. Randomised clinical trial: the efficacy and safety of propionyl-L-carnitine
CD4+CD25high regulatory T cells are enriched in the colonic mucosa of patients therapy in patients with ulcerative colitis receiving stable oral treatment. Aliment

6

S. Hone Lopez et al. Cancer Treatment Reviews 107 (2022) 102406

Pharmacol Ther 2011;34(9):1088–97. https://doi.org/10.1111/j.1365- [72] Dizman N, Meza L, Bergerot P, Alcantara M, Dorff T, Lyou Y, et al. Nivolumab plus
2036.2011.04844.x. ipilimumab with or without live bacterial supplementation in metastatic renal cell
[55] Leffler DA, Kelly CP, Green PH, et al. Larazotide acetate for persistent symptoms of carcinoma: a randomized phase 1 trial. Nature Med 2022;28(4):704–12. https://
celiac disease despite a gluten-free diet: a randomised controlled trial. doi.org/10.1038/s41591-022-01694-6.
Gastroenterology 2015;148:1311–9. https://doi.org/10.1016/S0016-5085(16)
30619-9. [73] Cammarota G, Ianiro G, Gasbarrini A. Fecal microbiota transplantation for the
[56] Celasco G, Papa A, Jones R, et al. Clinical trial: oral colon-release parnaparin treatment of Clostridium difficile infection: a systematic review. J Clin
sodium tablets (CB-01-05 MMX) for active left-sided ulcerative colitis. Aliment Gastroenterol 2014;48:693–702. https://doi.org/10.1097/
Pharmacol Ther 2010;31:375–86. https://doi.org/10.1111/j.1365- MCG.0000000000000046.
2036.2009.04194.x.
[57] Zhou QiQi, Verne ML, Fields JZ, Lefante JJ, Basra S, Salameh H, et al. Randomised [74] Colman RJ, Rubin DT. Fecal microbiota transplantation as therapy for
placebo-controlled trial of dietary glutamine supplements for postinfectious inflammatory bowel disease: a systematic review and meta-analysis. J Crohns
irritable bowel syndrome. Gut 2019;68(6):996–1002. https://doi.org/10.1136/ Colitis 2014;8:1569–81. https://doi.org/10.1016/j.crohns.2014.08.006.
gutjnl-2017-315136.
[58] Bindels LB, Delzenne NM, Cani PD, Walter J. Towards a more comprehensive [75] Sakurai T, De Velasco MA, Sakai K, Nagai T, Nishiyama H, Hashimoto K, et al.
concept for prebiotics. Nat Rev Gastroenterol Hepatol 2015;12(5):303–10. https:// Integrative analysis of gut microbiome and host transcriptomes reveals associations
doi.org/10.1038/nrgastro.2015.47. between treatment outcomes and immunotherapy-induced colitis. Mol Oncol 2022;
[59] Valcheva R, Koleva P, Martínez I, Walter J, Ga¨nzle MG, Dieleman LA. Inulin- type 16(7):1493–507. https://doi.org/10.1002/1878-0261.13062.
fructans improve active ulcerative colitis associated with microbiota changes and
increased short-chain fatty acids levels. Gut Microbes 2019;10(3):334–57. https:// [76] Davar D, Dzutsev AK, McCulloch JA, Rodrigues RR, Chauvin J-M, Morrison RM,
doi.org/10.1080/19490976.2018.1526583. et al. Fecal microbiota transplant overcomes resistance to anti-PD-1 therapy in
[60] Narula N, Kassam Z, Yuan Y, Colombel JF, Ponsioen C, Reinisch W, et al. melanoma patients. Science 2021;371(6529):595–602. https://doi.org/10.1126/
Systematic review and meta-analysis: fecal microbiota transplantation for science.abf3363.
treatment of active ulcerative colitis. Inflamm Bowel Dis 2017;23:1702–9. https://
doi.org/10.1097/MIB.0000000000001228. [77] Lee KA, Thomas AM, Bolte LA, Bjo¨rk JR, de Ruijter LK, Armanini F, et al. Cross-
[61] Pantavou K, Yiallourou AI, Piovani D, Evripidou D, Danese S, Peyrin-Biroulet L, cohort gut microbiome associations with immune checkpoint inhibitor response in
et al. Efficacy and safety of biologic agents and tofacitinib in moderate-to-severe advanced melanoma. Nat Med 2022;28(3):535–44. https://doi.org/10.1038/
ulcerative colitis: A systematic overview of meta-analyses. United European s41591-022-01695-5.
Gastroenterol J 2019;7(10):1285–303. https://doi.org/10.1177/
2050640619883566. [78] Zizzari I, Di Filippo A, Scirocchi F, Di Pietro F, Rahimi H, Ugolini A, et al. Soluble
[62] Dubois-Camacho K, Ottum PA, Franco-Mun˜oz D, De la Fuente M, Torres- immune checkpoints, gut metabolites and performance status as parameters of
Riquelme A, Díaz-Jime´nez D, et al. Glucocorticosteroid therapy in inflammatory response to nivolumab treatment in NSCLC patients. J Pers Med 2020;10(4):208.
bowel diseases: From clinical practice to molecular biology. World J Gastroenterol https://doi.org/10.3390/jpm10040208.
2017;23(36):6628–38. https://doi.org/10.3748/wjg.v23.i36.6628.
[63] D’Haens G. Systematic review: second-generation vs. conventional corticosteroids [79] Nomura M, Nagatomo R, Doi K, Shimizu J, Baba K, Saito T, et al. Association of
for induction of remission in ulcerative colitis. Aliment Pharmacol Ther 2016;44: short-chain fatty acids in the gut microbiome with clinical response to treatment
1018–29. https://doi.org/10.1111/apt.13803. with nivolumab or pembrolizumab in patients with solid cancer tumors. JAMA
[64] Zeissig S, Rosati E, Dowds CM, Aden K, Bethge J, Schulte B, et al. Vedolizumab is Netw Open 2020;3(4):e202895. https://doi.org/10.1001/
associated with changes in innate rather than adaptive immunity in patients with jamanetworkopen.2020.2895.
inflammatory bowel disease. Gut 2019;68(1):25–39. https://doi.org/10.1136/
gutjnl-2018-316023. [80] Botticelli A, Vernocchi P, Marini F, Quagliariello A, Cerbelli B, Reddel S, et al. Gut
[65] Hanauer SB. New lessons: classic treatments, expanding options in ulcerative metabolomics profiling of non-small cell lung cancer (NSCLC) patients under
colitis. Colorectal Dis 2006 May;8(Suppl 1):20–4. https://doi.org/10.1111/j.1463- immunotherapy treatment. J Transl Med 2020;18(1). https://doi.org/10.1186/
1318.2006.00988.x. s12967-020-02231-0.
[66] Sasson AN, Ingram RJM, Zhang Z, Taylor LM, Ananthakrishnan AN, Kaplan GG,
et al. The role of precision nutrition in the modulation of microbial composition [81] Coutzac C, Jouniaux J-M, Paci A, Schmidt J, Mallardo D, Seck A, et al. Systemic
and function in people with inflammatory bowel disease. Lancet Gastroenterol short chain fatty acids limit antitumor effect of CTLA-4 blockade in hosts with
Hepatol 2021;6(9):754–69. https://doi.org/10.1016/S2468-1253(21)00097-2. cancer. Nat Comm 2020;11(1). https://doi.org/10.1038/s41467-020-16079-x.
[67] Fritsch J, Garces L, Quintero MA, Pignac-Kobinger J, Santander AM, Ferna´ndez I,
et al. Low-fat, high-fiber diet reduces markers of inflammation and dysbiosis and [82] Abu-Sbeih H, Ali FS, Luo W, Qiao W, Raju GS, Wang Y. Importance of endoscopic
improves quality of life in patients with ulcerative colitis. Clin Gastroenterol and histological evaluation in the management of immune checkpoint inhibitor-
Hepatol 2021;19(6):1189–1199.e30. https://doi.org/10.1016/j.cgh.2020.05.026. induced colitis. J Immunother Cancer 2018;6:95. https://doi.org/10.1186/s40425-
[68] Spencer CN, McQuade JL, Gopalakrishnan V, McCulloch JA, Vetizou M, Cogdill AP, 018-0411-1.
et al. Dietary fiber and probiotics influence the gut microbiome and melanoma
immunotherapy response. Science 2021;374(6575):1632–40. https://doi.org/ [83] Abu-Sbeih H, Ali FS, Wang X, et al. Early introduction of selective
10.1126/science.aaz7015. immunosuppressive therapy associated with favourable clinical outcomes in
[69] Judkins TC, Archer DL, Kramer DC, Solch RJ. Probiotics, nutrition, and the small patients with immune checkpoint inhibitor-induced colitis. J Immunother Cancer
intestine. Curr Gastroenterol Rep 2020;22:2. https://doi.org/10.1007/s11894- 2019;2(7):93. https://doi.org/10.1186/s40425-019-0577-1.
019-0740-3.
[70] Zeng J, Li YQ, Zuo XL, Zhen YB, Yang J, Liu CH. Clinical trial: effect of active lactic [84] Gambichler T, Brown V, Steuke AK, Schmitz L, Stockfleth E, Susok. Baseline
acid bacteria on mucosal barrier function in patients with diarrhoea-predominant laboratory parameters predicting clinical outcome in melanoma patients treated
irritable bowel syndrome. Aliment Pharmacol Ther 2008;28:994–1002. https:// with ipilimumab: a single-centre analysis. J Eur Acad Dermatology Venereol. 2018;
doi.org/10.1111/j.1365-2036.2008.03818.x. 32:972–977. doi: 10.1111/jdv.14629.
[71] Mardini HE, Grigorian AY. Probiotic mix VSL#3 is effective adjunctive therapy for
mild to moderately active ulcerative colitis: a meta-analysis. Inflamm Bowel Dis [85] Hone Lopez S, Kats-Ugurlu G, Renken RJ, Buikema HJ, de Groot MR,
2014;20:1562–7. https://doi.org/10.1097/MIB.0000000000000084. Visschedijk MC, et al. Immune checkpoint inhibitor treatment induces colitis with
heavy infiltration of CD8 + T cells and an infiltration pattern that resembles
ulcerative colitis. Virchows Arch 2021;479(6):1119–29. https://doi.org/10.1007/
s00428-021-03170-x.

[86] National Library of Medicine (U.S.). (2021, October -). Deep Phenotyping of the
Gut Immune System During Immune Checkpoint Inhibitor Therapy – DEFENCE.
Identifier NCT04600180. https://clinicaltrials.gov/ct2/show/NCT04600180.

[87] Chulkina M, Beswick EJ, Pinchuk IV. Role of PD-L1 in Gut Mucosa Tolerance and
Chronic Inflammation. Int J Mol Sci 2020;21:9165. https://doi.org/10.3390/
ijms21239165.

[88] Barnes MJ, Griseri T, Johnson AM, Young W, Powrie F, Izcue A. CTLA-4 promotes
Foxp3 induction and regulatory T cell accumulation in the intestinal lamina
propria. Mucosal Immunol 2013;6:324–34. https://doi.org/10.1038/mi.2012.75.

7

Cancer Treatment Reviews 107 (2022) 102405

Contents lists available at ScienceDirect

Cancer Treatment Reviews

journal homepage: www.elsevier.com/locate/ctrv

Anti-tumour Treatment

The paradigm shift in treatment from Covid-19 to oncology with
mRNA vaccines

Jiao Wei, Ai-Min Hui *

Shanghai Fosun Pharmaceutical Industrial Development, Co., Ltd., 1289 Yishan Road, Shanghai 200233, China
Fosun Pharma USA Inc, 91 Hartwell Avenue, Suite 305, Lexington, MA 02421, USA

ARTICLE INFO ABSTRACT

Keywords: mRNA vaccines have gained popularity over the last decade as a versatile tool for developing novel therapeutics.
mRNA The recent success of coronavirus disease (COVID-19) mRNA vaccine has unlocked the potential of mRNA
Cancer vaccine technology as a powerful therapeutic platform. In this review, we apprise the literature on the various types of
Covid-19 cancer vaccines, the novel platforms available for delivery of the vaccines, the recent progress in the RNA-based
Oncology therapies and the evolving role of mRNA vaccines for various cancer indications, along with a future strategy to
Optimization treat the patients. Literature reveals that despite multifaceted challenges in the development of mRNA vaccines,
the promising and durable efficacy of the RNA in pre-clinical and clinical studies deserves consideration. The
introduction of mRNA-transfected DC vaccine is an approach that has gained interest for cancer vaccine
development due to its ability to circumvent the necessity of DC isolation, ex vivo cultivation and re-infusion.
The selection of appropriate antigen of interest remains one of the major challenges for cancer vaccine devel­
opment. The rapid development and large-scale production of mRNA platform has enabled for the development
of both personalized vaccines (mRNA 4157, mRNA 4650 and RO7198457) and tetravalent vaccines (BNT111 and
mRNA-5671). In addition, mRNA vaccines combined with checkpoint modulators and other novel medications
that reverse immunosuppression show promise, however further research is needed to discover which combi­
nations are most successful and the best dosing schedule for each component. Each delivery route (intradermal,
subcutaneous, intra tumoral, intranodal, intranasal, intravenous) has its own set of challenges to overcome, and
these challenges will decide the best delivery method. In other words, while developing a vaccine design, the
underlying motivation should be a reasonable combination of delivery route and format. Exploring various
administration routes and delivery route systems has boosted the development of mRNA vaccines.

Introduction modification and stabilization of mRNA led to its recognition as a
resourceful platform for developing novel therapy [4,5]. mRNA vaccines
Vaccinations play a vital role in reducing disease, disability, and thus hold a lot of promise and confer several advantages over traditional
mortality from a variety of infectious diseases [1]. The use of conven­ vaccines.
tional vaccines such as live attenuated vaccines, inactivated pathogens,
subunit vaccines or toxoid vaccines provides durable efficacy against The recent outbreak of SARS-CoV-2 and coronavirus disease (Covid-
various infectious diseases [2]. Nucleic acid vaccines mainly, plasmid 19) has demonstrated an urgent need of rapid vaccine development.
DNA(pDNA) and messenger RNA (mRNA), came to existence in 1900s Two mRNA vaccines, BNT162b2 (Pfizer-BioNTech) and mRNA-1273
due to their innate ability to stimulate inoculation with live organism- (Moderna TX), have acquired authorization from FDA that are
based vaccines, notably for cell-mediated immune stimulation [3]. For currently being used to prevent COVID-19 [6]. Both vaccines have good
several decades later, pDNA-based approaches dominated the field, efficacy as demonstrated in the various phase III trials and real world
since mRNA-based approach was considered unstable due to inefficient studies [7–11]. Knowledge gained from these trials and versatile ther­
in-vivo delivery and excessive stimulation of inflammatory responses apeutic potential of the mRNA can be applied for the development of
[4,5]. Eventually in late 2000s, a series of improvement in manufacture, vaccine for the infectious diseases and cancer. In this review, we focus
on the therapeutic aspect of mRNA vaccines as a cancer therapy. In

* Corresponding author at: Fosun Pharma USA Inc, 91 Hartwell Avenue, Suite 305, Lexington, MA 02421, USA.
E-mail address: [email protected] (A.-M. Hui).

https://doi.org/10.1016/j.ctrv.2022.102405
Received 5 February 2022; Received in revised form 25 April 2022; Accepted 29 April 2022
Available online 5 May 2022
0305-7372/© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-
nc-nd/4.0/).

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

addition, we would apprise the literature on the various types of cancer individuals with asymptomatic or mild symptomatic metastatic
vaccines, the novel platforms available for delivery of the vaccines, the castration-resistant prostate cancer (mCRPC) [14]. Besides, therapeutic
recent progress in the RNA-based therapies and the evolving role of vaccines are available for the treatment of early-stage bladder cancer
mRNA vaccines for various cancer indications, the available clinical and (TheraCys® and TICE® Bacillus Calmette-Guerin (BCG)) [15] and
preclinical studies with the future chapter in treatment of patients. melanoma [IMLYGIC® (talimogene laherparepvec/T-VEC)] [16].
Despite significant attempts to produce cancer vaccines, clinical trans­
The available platforms for development of anti-cancer vaccines lation of cancer vaccines into effective therapeutics has remained diffi­
cult for decades due to the wide range of tumor antigens and low
Cancer vaccines are a promising new immunotherapeutic strategy immune response [17], originating the need to develop more potent
for both prevention and treatment. Vaccines targeting tumor associated vaccine approaches. Furthermore, there is a growing demand for vac­
or tumor-specific antigens (TAAs or TSAs) can destroy malignant cells cine development, large-scale manufacture, and dissemination, partic­
that overexpress the antigens due to immunologic memory, resulting in ularly in the case of non-viral diseases such as cancer [18,19].
a durable therapeutic response. Compared to other immunotherapies,
cancer vaccines provide a precise, safe, and acceptable treatment. In general, cancer vaccine platforms are classified into tumor cell,
Currently, 2 prophylactic vaccines have been approved by the U.S. Food peptide, viral vector, dendritic cell (DC), DNA and RNA types (Fig. 1).
and Drug Administration (FDA) for routine use in clinical practice. Allogenic or autologous patient-derived tumor cells are used to make
Gardasil-9 is approved for prevention of HPV infection that is the cause cellular vaccines [20]. This approach is beneficial in that target antigens
of most HPV cancers. The other one is hepatitis B (HBV) vaccine, for does not have to be determined in advance [21]. The whole cell cancer
example HEPLISAV-B, to prevent HBV infection that is known to cause vaccine approach using granulocyte–macrophage colony-stimulating
hepatocellular carcinoma [12,13]. factor (GM-CSF) has been studied in several types of cancer both in
animals as well as human trials. The phase I and II studies with alloge­
In 2010, PROVENGE (sipuleucel-T), an immune-cell based thera­ neic GM-CSF–transduced vaccine post-radiation (derived from two
peutic cancer vaccine was granted approval for the treatment of pancreatic tumor lines) demonstrated durable efficacy and prolonged

Fig. 1. The commonly available platforms and mechanisms for cancer vaccine development. (a) Whole cell-based vaccines (an autologous tumor cell vaccine using a
patient’s own cancer cells is injected as vaccine). (b) Viral vector-based vaccines (the genome of viral particles is modified to contain one or more genes encoding for
the antigens of interest). (c) Dendritic cell-based vaccines (the dendritic cells efficiently capture the antigens, internalize, and process into peptides that are then
presented in the context of MHC I and II molecules. These complexes are later recognized by the T-cell receptor (TCR) of CD8+ and CD4 + T cells) (d) DNA based
vaccines (DNA plasmids are designed to deliver genes encoding TAs, eliciting or augmenting the adaptive immune response towards TA-bearing tumor cells. It
induces the innate immune response, stimulates several DNA-sensing pathways in the cytosol of transfected cells due to the presence of CpG motifs and the double
stranded structure itself) (e) Peptide-based vaccines (the peptides bind with the restricted MHC molecule expressed in APC. The peptide/MHC complex is then
transported to the cell surface after intracellular processing and later recognized by the TCR on the surface of T cells, leading to activation of T lymphocytes) (f) RNA
based vaccines (conventional non-replicating mRNA consists of 5 structural elements such as cap structures, a 5′ untranslated region (5′-UTR), an open reading frame
encoding antigens of interest, a 3′-UTR; and an adenine repeating nucleotide sequence that forms a polyadenine (poly(A) tail. The non-replicating mRNA encodes
antigen of interest, while self-amplifying mRNA encodes antigen of interest and a replication machinery, a self-replicating single-stranded RNA virus).

2

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

survival in patients with pancreatic cancer [22,23]. DNA) expressing one or more tumor antigens. The capacity of DNA
Peptide vaccines are made up of amino acid sequences that contain vaccines lies in its ability to combine many genes expressing numerous
tumor-antigens to establish a precise and broader adaptive immune
an epitope which can cause an immune response. Due to the difficulties response at the same time. However, these vaccines are poorly immu­
of small peptides to attach directly to major histocompatibility com­ nogenic [24]. To improve the immunological response of DNA vaccines,
plexes (MHC) I molecules, long peptides (containing of between 25 and researchers have looked into encoding xenogeneic versions of antigens,
35 amino acids) are frequently favored over short peptides (consisting of fusing antigens with compounds that activate T cells or trigger asso­
approximately 10 amino acids). Short peptides also fail to activate CD4 ciative recognition, DNA vector priming followed by viral vector
helper T cells, which are required for full cytotoxic T lymphocyte acti­ boosting, and immunomodulatory molecules [26]. In contrast, RNA
vation (CTLs). These shortcomings can be overcome by using a long- cancer vaccines are superior to DNA vaccines. While RNA is more sus­
peptide vaccine, that forces dendritic cells (DCs) to phagocytose the ceptible to RNase breakdown, this can be minimized through chemical
long-peptide before it is exposed on MHC I and attached to T cells. Long changes and the insertion of modified nucleosides such as pseudo uri­
peptide vaccines also increase the HLA-related compatibility that exist dine. Furthermore, unlike DNA, which must overcome the second bar­
with short-peptide vaccine. Furthermore, using a long peptide vaccine rier, the nuclear membrane, to reach the nucleus, RNA just needs to
permits APCs to be presented via MHC II, which stimulates CD4+ enter the cytoplasm [21]. The encoded proteins are converted into
lymphocytes, allowing for a more efficient immune response against peptides that are present on MHC I and II to excite CD8+ and CD4+ T
tumor cells. However, because peptides are not self-immunogenic, cells, respectively, after RNA translation. The fundamental pharma­
administering an adjuvant at the same time is required for producing cology of mRNA vaccines is presented in Fig. 2.
maximum efficiency [24]. So far, the peptide-based vaccines tested in
laboratory has been able to elicit limited tumor-targeting immune re­ Given the importance of DCs in initiating adaptive immunity in vitro
sponses, mostly because of intrinsic changes in cancer cells that reduce and in vivo through generating CTLs, mRNA-transfected DC vaccine is
antigenicity and/or changes immunosuppressive alterations in the an approach gaining interest for cancer vaccine development [24]. DC-
tumor microenvironment [25]. Therefore, other approaches are being based mRNA cancer vaccines have shown promising effects in various
developed including its combination with other immunotherapies, tar­ phases of clinical trials. Boczkowski and colleagues in 1996 first
geting antigenic epitopes arising from tumor cells and identifying target demonstrated that electroporation of DCs with mRNA could elicit potent
population [25]. immune responses against tumor in mice [27]. Since then, several
human trials with electroporation of DCs have been conducted [28,29].
Genetically modified viruses are also used for mRNA delivery. Bulk mRNA isolated from autologous tumors is another method for
Application of positive strand RNA viruses via translation with host ri­ pulsing DCs with tumor antigen-loaded mRNA [30,31]. Direct injection
bosomal machinery. However, challenges with host genome integration of mRNA can be used instead of DC vaccines since it eliminates the need
and the likelihood of host rejection, as well as cytotoxicity and immu­ for DC isolation, ex vivo cultivation, and re-infusion [32]. Directly
nogenicity, remains the major challenges. The MHC allows cancer cells injecting the mRNA into secondary lymphoid tissue aids in delivering
to create peptide antigens that are present on their membrane surface. T antigen to APCs at the T cell activation site, circumventing the need for
cell receptors (TCRs) on cytotoxic T lymphocytes (CTLs) identify these DC movement [33].
antigens, resulting in cancer cell lysis. The antiviral immune response
neutralizes viral vectors, limiting the number of vaccines that can be Unlocking the potential of mRNA cancer vaccines
given [21].
The cancer vaccines have the ability to elicit immune response to
Finally, to boost the adaptive immune system against tumor anti­
gens, DNA cancer vaccines are created from bacterial plasmids (naked Fig. 2. Mechanism of action of mRNA
vaccines. 1. In a cell-free system, mRNA is
in vitro transcribed (IVT) from a DNA
template. 2. IVT mRNA is then transfected
into dendritic cells (DCs) by the process of
(3) endocytosis. 4. Endosomal escape al­
lows entrapped mRNA to be released into
the cytoplasm. 5. The mRNA is translated
into antigenic proteins using the ribosome
translational mechanism. After post-
translational modification, the translated
antigenic protein is ready to act in the cell
where it was produced. 6. The protein gets
secreted by the host cell. 7. Antigen proteins
are digested in the cytoplasm by the pro­
teasome and transferred to the endoplasmic
reticulum, where they are loaded onto MHC
class I molecules (MHC I). 8. MHC I-peptide
epitope complexes with loaded MHC I-
peptide epitopes produced, resulting in in­
duction. 9. Exogenous proteins are taken up
DCs. 10. They are degraded in endosomes
and delivered via the MHC II pathway.
Furthermore, to obtain cognate T-cell help
in antigen-presenting cells, the protein
should be routed through the MHC II
pathway. 11. The generated antigenic pep­
tide epitopes are subsequently loaded onto
MHC II molecules.

3

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

tumor antigens. The selection of a suitable target antigen is pivotal in the with pembrolizumab monotherapy in high-risk recurrent individuals
development of a vaccine design. Currently, the majority of vaccinations with complete resection of tumor (NCT03897881). A first-in-human
are TAAs, which are self-proteins that are improperly expressed by phase Ib study of RO7198457, a combination of systemically adminis­
cancerous cells [21]. Developing vaccines against TAAs is challenging, tered RNA-Lipoplex iNeST with the PD-L1 antibody atezolizumab is
as B- and T-cells might be subjected to removal by central and peripheral presently conducted in patients with locally advanced or metastatic
tolerance [34]. Besides, along with overexpression on tumor cells, TAAs solid tumors. The preliminary results of this study suggest significant
might also be expressed in normal healthy cells leading to collateral level of neoantigen immune-tumor response. A randomized phase II
damage [21]. In contrast, TSAs, which consists of neoantigens and viral study of RO7198457 in first-line for patients with melanoma in combi­
oncoproteins are expressed only in cancerous cells. The prophylactic nation with pembrolizumab is currently ongoing, and 2 randomized
viral oncoproteins work by inducing the production of powerful clinical trials are planned for the adjuvant treatment of individuals with
neutralizing antibodies that block viral entrance into host cells and non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) [43].
neoplasia caused by viruses [21]. However, these vaccines were inef­
fective in curing cancer as humoral immunity cannot effectively elimi­ Tetravalent vaccine and combination therapies
nate larger number of virus-infected cancer cells [21]. Neoantigens, like
viral oncoproteins, are specific to tumor cells and are recognized by the A tetravalent RNA-lipoplex cancer vaccine, BNT111, contains 4 types
immune system as foreign substances. Lately, neoantigens are being of naked RNA such as RBL001.1, RBL002.2, RBL003.1, and RBL004.1
considered as a potential target in the progress of anti-cancer vaccine encoding 4 melanoma-associated antigens (MAAs), the cancer-testis
development. Numerous pre-clinical trials and early phase clinical trials antigen NY-ESO-1, the human MAGE- A3, tyrosinase, and putative
have shown the ability of neoantigen based vaccines to minimize the tyrosine-protein phosphatase (TPTE), encapsulated in liposomes. The
potential induction of central and peripheral tolerance as well as the risk vaccine upon intravenous administration is taken up by the APCs, and
of autoimmunity [35,36]. after being translocated to the cytoplasm, is translated into the 4 tumor-
associated proteins. As a result, CD8+ and CD4+ T-cell responses
TAAs with shared expression across cancer types, such as melanoma- against 4 selected antigens are produced [44]. A phase I trial showed
associated antigen (MAGE1) and NY-ESO-1.37, has encouraged studies that this vaccine alone and in combination with immune checkpoint
to target TAAs that are habitually overexpressed in a certain type of inhibitors (ICIs) induced durable objective responses and exhibited a
cancer, along with the prospect of generating a common vaccine per favorable safety profile among patients with advanced melanoma [45].
tumor type [37]. Empirical clinical experience has also suggested that A phase II trial is ongoing to evaluate the vaccine candidate in combi­
vaccines targeting specific tumor antigens are ineffective in tackling nation with the anti-PD-1 antibody cemiplimab for patients with unre­
tumor heterogeneity, as well as in dealing with the challenges of clonal sectable stage III or stage IV melanoma who are refractory to or relapsed
evolution and immune evasion by the tumor [38]. As a result, with the after anti-PD-1 therapy [46].
increasing importance of therapeutic cancer vaccines, the rapid devel­
opment and large-scale production using mRNA platform introduces the mRNA-5671, another tetravalent vaccine, is an LNP-formulated
potential for the development of both personalized vaccines and off- mRNA-based vaccine that targets 4 of the most frequent KRAS muta­
shelf cocktail vaccines. tions (G12D, G13D, G12C and G12V). APCs take up and translate
mRNA-5671 after immunization. Following translation, the MHCs dis­
Personalized cancer vaccines (PCV) plays the epitopes on the surface of APCs, resulting in the development
of both cytotoxic T-lymphocyte- and memory T-cell-dependent immune
The neoantigens remain unique for each individual, with their responses directed at tumor cells with KRAS mutations [47]. CD8 T cell
numbers varying on the type of cancer. This necessitates for a tailored responses to KRAS antigens were considerably improved in preclinical
approach in which the tumor genome is sequenced and mutations are investigations after immunization with mRNA encoding KRAS muta­
detected, neoantigens are predicted using computerized algorithms and tions [48]. Patients with advanced or metastatic NSCLC, colorectal
a vaccine is then created and delivered to the patient. Mice vaccinated cancer, or pancreatic adenocarcinoma and KRAS mutations are being
with a computationally engineered synthetic mRNA comprising enrolled in a phase I research using mRNA-5671 with or without pem­
numerous MHC class II neoepitopes showed 100% tumor rejection in brolizumab (NCT03948763).
preclinical studies, demonstrating antigen distribution [39]. The safety
and efficacy of this approach was established in a first-in-human clinical Due to heterogenous and ever evolving nature of cancer mechanisms,
study involving 13 patients with metastatic melanoma. Each patient was the clinical benefit of monotherapy regimen in patients with advanced
given a vaccine that contained 10 neoepitopes specific to their tumor. In cancer is not adequate. Tumor-specific T lymphocytes produced by
certain patients, antitumor responses were discovered in metastases vaccines do not operate efficiently against the tumor due to their lack of
removed after immunization, where T-cell infiltration and neoepitope- motility and/or gradual depletion. As a result, combining procedure that
specific apoptosis of autologous tumor cells were discovered after prevent immune escape pathways is critical [49]. For instance, a phase II
vaccination. All patients exhibited CD4+ and CD8+ T-cell responses clinical trial in chemotherapy treated patients with metastatic
[40]. Since then, therapeutic cancer treatment with tailored mRNA castration-resistant prostate cancer (mCRPC) showed similar and dura­
vaccines has received a lot of interest, and several clinical trials are ble tumor immune responses on addition of DC vaccines [50]. Mono­
presently underway, according to the US National Library of Medicine. A clonal antibodies (mAbs) targeting CTLA-4 and the PD-1/PD-L1
recent study with mRNA-4650, a KRAS personalized vaccine, developed expression have revolutionized the treatment paradigm for several types
by Moderna and Merck, in combination with or without pembrolizumab of cancers, including renal cancer, melanoma, bladder cancer, lung
was conducted to treat patients with pancreatic carcinoma. The lipid cancer and Hodgkin’s lymphoma [51]. CureVac GmbH systemic mRNA
nanoparticles (LNPs) approach for delivery of mRNA-4650 showed well- immunotherapy and local irradiation therapy can eradicate established
tolerated anti-tumoral immune response [41]. Another personalized macroscopic E.G7-OVA and LLC cancers in a synergistic manner.
vaccine, mRNA-4157, targeting 20 TAAs and useful in treating various Moreover, this combination boosted CD4+, NKT and CD8+cell infiltra­
types of tumors, in single or in combination with pembrolizumab tion in tumor infected mouse [52]. CV9202, vaccine encoding 6 NSCLC-
demonstrated acceptable safety profile with cytotoxic T-lymphocyte associated antigens (NY-ESO-1, MUC-1, MAGE-C2, MAGE-C1, 5T4 and
(CTL)- and memory T-cell-dependent immune responses [42]. Based on survivin) have been proven to induce targeted immune responses. The
the ability of mRNA-4157 to elicit clinical response, a phase II trial is combination of this vaccine with radiotherapy in a phase Ib clinical trial
currently undergoing to evaluate the efficacy of the postoperative in 26 stage IV NSCLC patients revealed elevated CV9202 antigen-
adjuvant therapy with mRNA-4157 and pembrolizumab in comparison specific immune responses in 84% of patients, with 80% increased
antigen-specific antibody levels, 40% patients with functional T cells

4

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

and about 52% of patients had multiple antigen specificities [53]. In fully specialized treatment targeting specific mutations in each patient.
another study, researchers used an mRNA vaccine expressing the TAA The ongoing trials related to mRNA vaccine in breast cancer is listed in
MUC1 in combination with an anti-CTLA-4 monoclonal antibody to Table 1.
boost the vaccine’s immune response against triple-negative breast
cancer (TNBC) by improving T cell activity [54]. Non-small cell lung cancer

Recent advancement of mRNA vaccines in various types of Lung cancer remains a major cause of cancer worldwide after breast
cancer cancer. Despite recent therapeutic advancements, the overall 5-year
survival rate for LC is still less than 20%. Because most cancers exhibit
Preclinical and clinical evidence have shown that using mRNA for mutational variability, conventional cancer treatment techniques, such
prophylaxis and therapy can help prevent infectious disease and treat as surgery and chemotherapy, are far from optimum, especially for
cancers, and that mRNA vaccines are safe and well tolerated in both advanced stage malignancies. Currently, the information related to
animal models and humans. Further enhancements might also boost mRNA-based approach in treatment for NSCLC is limited. CV9201 is a
antigen-specific immune responses as well as B and T cells immune re­ cancer immunotherapy based on RNActive® that encodes 5 NSCLC an­
sponses [55]. As of 21st December 2021, 23 RNA vaccines are currently tigens: melanoma antigen family C1/C2, NY esophageal squamous cell
under phase I/II/III clinical trials, while 24 vaccines are at pre-clinical carcinoma-1, trophoblast glycoprotein and survivin. About 46 patients
stage. with locally advanced (n = 7) or metastatic (n = 39) NSCLC received 5
intradermal CV9201 injections (400–1600 g of mRNA) in a phase I/IIa
Breast cancer dose-escalation experiment. After initial dose administration, the me­
dian progression-free survival and OS were 5.0 months (95 percent CI
Breast cancer remains a cause of mortality for women globally [56]. 1.8–6.3) and 10.8 months (8.1–16.7), respectively. In addition, 60% of
More often, 81% women suffer from invasive breast cancer, which patients reported an increased frequency of >2 fold followed by acti­
comprises of at least 21 distinct histological subtypes and 4 molecular vation of IgD+ CD38hi B cells. This showed that CV9201 was well
subgroups (luminal A, luminal B, triple-negative and HER2-enriched) tolerated, and immunological responses could be observed following
that differ in risk factors, presentation, response to treatment, and out­ therapy, indicating that further clinical research is warranted [68]. The
comes [57]. Invasive breast cancer can spread to adjacent lymph nodes ongoing trials related to mRNA vaccine in breast cancer is listed in
or other organs over time. It is because of widespread metastasis that a Table 2.
woman dies from breast cancer [58]. Using modern methodologies for
mRNA sequencing, such as The Cancer Genome Atlas (TCGA) data, it has Prostate cancer
been established that increased expression of T- and B-cell predicts
higher overall survival (OS) in a variety of tumor types, including breast The standard treatment for prostate cancer includes androgen
cancer [59]. The current treatment approach for breast cancer includes deprivation and chemotherapy. However, patients become resistant
radiation therapy, surgery, chemotherapy, as well as hormonal and after prolonged treatment with these agents. Relapse or progression of
targeted therapies. Lately, the development of medications that can disease occur even after complete androgen blockage and when plasma
prevent breast cancer from developing in the first place, as well as their concentrations of testosterone are reduced to <50 ng/dL by castration or
recurrence, has gathered attention. The overexpression of high-affinity gonadotropin-releasing hormone analogs, and the effects of the
transmembrane receptors such as HER3, HER2, c-MET, EGFR, and the remaining androgens are suppressed by androgen receptor antagonists
transmembrane protein epithelial mucin-1 (MUC-1) are the key onco­ [69]. With the advent of Sipuleucel-T, a dendritic-cell based vaccine, for
genic drivers for breast cancer [60]. Treatment of breast cancer, espe­ treatment of advanced stages of prostate cancer, immunotherapy for
cially, TNBC is gaining importance, since lack of therapeutic targets prostate cancer has come into limelight. However, besides sipuleucel-T,
makes such type of cancer unresponsive to typical endocrine therapies there have been disappointing results in prostate cancer. In patients with
and HER2-targeted therapy. In such a case, cancer vaccines which aid in mCRPC, large phase III studies of the CTLA-4 inhibitor, ipilimumab did
activation and amplification of TAA-specific immunity combined with a not show significant benefit in OS compared to placebo before or after
sustained memory T cell immune response may be an effective therapy chemotherapy treatment. In addition, nivolumab, a single-agent PD-1
for preventing breast cancer recurrence in patients [61]. Previous antibody, was found to have little effect in men with mCRPC. However,
vaccination strategies in adjuvant settings, against HER2+ self-antigens administering both CTLA-4 and PD-1 inhibitors combination has resul­
have shown substantial efficacy in patients with breast cancer [62–64]. ted in some PSA and objective responses, showing that a minority of
However, such an approach is usually weak as immune response as T- patients may benefit. Pembrolizumab was given to mCRPC patients who
lymphocytes have affinity to HER2+ and thus are subject to central were advancing on enzalutamide in a recent study, and a significant
tolerance [65]. An ongoing phase I/II trial is being conducted in patients number of men had remarkable PSA and objective responses. PSA and
with TNBC and who completed standard of care chemotherapy, where objective responses appeared to be more common in another small trial
patients are allocated to receive either 8 vaccination cycles of mRNA
WAREHOUSE vaccine (containing pre-formulated, shared tumor anti­ Table 1
gens, non-mutated) or mRNA MUTANOME vaccine (containing indi­ Clinical trials for breast cancer.
vidual mutations). The preliminary data of this trial showed mRNA
WAREHOUSE is feasible approach for treatment of TNBC [66]. Another Conditions NCT number Study Interventions Status
phase I trial from the Schmidt and colleagues was conducted with the design Active, not
addition of a third arm where patients were injected with IVAC_M_uID IVAC_W_bre1_uID/ recruiting
[Individualized NeoAntigen Specific Immunotherapy (iNeST)] which Triple NCT02316457 Phase I IVAC_M_uID
encodes 20 cancer mutations neoepitopes derived from NGS. The initial negative Terminated
results reported promising results of iNeST IVAC_M_uID in inducing Breast NCT00003432 Phase carcinoembryonic
strong polyepitope T-cell responses in patients with TNBC in the post- Cancer I/II antigen RNA-pulsed Recruiting
(neo)adjuvant phase or post-surgery. All the patients reported CD4+ DC cancer vaccine Recruiting
and/or CD8+ T-cell responses against 1 to 10 of the vaccine neoepitopes Breast Trimix mRNA
[67]. Theoretically, this treatment regimen will lead to a transition from Cancer
an individualized therapy targeting a single biomarker (e.g., HER2) to a mRNA-2752/
Breast NCT03788083 Phase I Durvalumab
Cancer NCT03739931 Phase I

Breast
Cancer

5

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

Table 2 NCT Number Study type Interventions Status
Clinical trials for non-small cell lung cancer. NCT03908671
Observational Personalized mRNA Tumor Vaccine Not yet recruiting
Conditions NCT03164772 study
NCT03948763 Phase II Durvalumab/Tremelimumab/BI 1361849 Completed
Non-Small Cell Lung Cancer Phase I V94/Pembrolizumab Active, not
recruiting
Metastatic Non-small Cell Lung Cancer NCT04998474 Phase II FRAME-001 personalized vaccine Not yet recruiting
Non-Small Cell Lung Cancer NCT02688686 Phase I/II Genetically modified dendritic cells + cytokine-induced Unknown
killer
Non-Small Cell Lung Cancer NCT03166254 Phase 1 Pembrolizumab/NEO-PV-01 vaccine/Poly ICLC Withdrawn
Non-Small-Cell Lung Cancer With Bone NCT00923312 Phase I/II CV9201 Completed
NCT04355806 Prospective PD-1/PD-L1 inhibitors/Inactivated trivalent influenza Not yet recruiting
Metastases vaccine
Non-Small Cell Lung Cancer NCT04267237 Phase II Atezolizumab/RO7198457 Withdrawn
Stage IIIB/IV Non-Small Cell Lung Cancer
Non-Small Cell Lung Cancer

Stage II-III Non-Small Cell Lung Cancer

combining ipilimumab and nivolumab than with either treatment alone, tumor response, demonstrating effective adaptive immune. The vac­
and it was suggested that patients with DNA repair gene mutations cine significantly reduced 80% of tumor growth when given before
benefited the most. Finally, in a limited fraction of individuals with tumor engraftment and suppressed tumor growth by 60% when given
prostate cancer, pembrolizumab, which was recently licensed for post tumor engraftment in syngeneic allograft mouse models of lym­
mismatch repair-deficient or microsatellite-unstable tumors, might be phoma and prostate cancer. These data imply that adding C16-R848
beneficial. The use of synthetic nucleotide-based DNA or RNA vaccines adjuvant pulsation to mRNA vaccine NP is a rational design strategy
is an alternative route for in vivo cancer vaccine design. The use of for improving the efficacy of synthetic mRNA vaccines [77]. Further,
plasmid DNA expressing TAAs to stimulate humoral and cellular im­ clinical trials related to mRNA vaccine in prostate cancer is listed in
mune responses has been shown earlier. However, in contrast to the
features of mRNA, the potential of DNA-based anti-cancer vaccines Table 3
integrating into the host genome and resulting in malignant trans­ Clinical trials for prostate cancer.
formation is a major barrier. Due to the instability of natural mRNA
molecules, Cure Vac (Tubingen, Germany) had developed RNActive® Study NCT number Study Intervention Status
vaccines, which are mRNA molecules optimized to elicit powerful, well- population design Completed
balanced immunological responses including humoral and cellular re­ CV9103
sponses, effector and memory responses, and Th1 and Th2 immune cell Hormonal NCT00831467 Phase Withdrawn
activation. These molecules stimulate the immune system by inter­ Refractory NCT01153113 I/II hTERT Active, not
reacting with toll-like receptor 7 and do not modify the primary amino Prostate mRNA DC recruiting
acid sequences [70]. Initial assessment of immune response in com­ Cancer Phase Dendritic cell Completed
pounds encoding prostate specific membrane antigen (PSMA) or oval I/II vaccine Terminated
albumin demonstrated strong humoral immune response with Th2 and mCRPC Phase Dendritic Cells Completed
Th1 cells, with repeated immunization increasing the frequency of IFN- I/II (DC) prostate
γ-secreting CD8+ T cells while maintaining CD4+ regulatory T cells Prostate Cancer NCT01197625 Phase CV9104 Unknown
frequency [70]. I/II
Prostate cancer NCT01278914 Phase mRNA transfected Terminated
Early intervention in patients with hormone-refractory prostate I/II dendritic cell/ Completed
cancer with CV9103 elicited significant cytotoxic T-cell response against mCRPC NCT01817738 Phase Docetaxel
all tested PSAs. A phase I/IIa clinical study with CV9103, a prostate II Autologous Completed
cancer vaccine containing 4 antigens, mainly, tumor associated antigens Prostate cancer NCT01446731 dendritic cells
PSA, PSMA, prostate stem cell antigen and six transmembrane epithelial transfected with Completed
antigen of the prostate 1, displayed a high level of immunogenicity in Prostate Cancer NCT00006430 Phase I amplified tumor
patients with mCRPC, where, 58% responders reacted against multiple RNA Terminated
antigens. About 74% patients had antigen-unspecific B-cells, while 79% Prostate Cancer NCT02140138 Phase CV9104
of responders had antigen-specific T-cells. One patient displayed >85% Prostate Cancer NCT02692976 II Recruiting
drop in his PSA-level [71]. Though the initial responses in these trials Phase mDC vaccine/pDC Terminated
were encouraging, the subsequent trial with CV9104 for prostate cancer II vaccine/mDC and
were terminated due to no significant effect on OS [72]. These findings pDC vaccine Active, not
indicate that selection of antigen is crucial for activating APCs and im­ Prostate cancer NCT00108264 Phase I Tumor RNA recruiting
mune response. Several studies have highlighted the efficacy of mRNA transfected
vaccine in other therapeutic areas [73,74]; when MS2 delivery platform Prostate cancer NCT00004211 Phase dendritic cells
is used. Using recombinant protein technology, the MS2 capsid can Prostate cancer I/II PSA RNA-pulsed
interact with specific 19-nucleotide stem-loop, can pack the target RNA, dendritic cell
thereby preventing degradation by nucleases [75]. Li et al. observed that NCT00010127 Phase I vaccine
MS2 virus-like particles (VLPs)-based hPAP–GM–CSF mRNA vaccine Therapeutic
might decrease prostatic-tumor growth in C57BL/6 mice, implying that Prostate cancer NCT04382898 Phase autologous
this vaccine could elicit an effective immune response in a short period NCT00906243 I/II dendritic cells
of time and is a viable treatment for prostate tumors [76]. The recent Hormonal Phase BNT112 with
advancement in prostate cancer is the delivery of mRNA as nanoparticle. Refractory I/II Cemiplimab
The co-delivery of C16-R848 adjuvant-pulsed mRNA vaccination with Prostate CV9103
OVA RNA increased TAA presentation while simultaneously stimulating Cancer NCT01784913 Phase
CD8+ T cell expression into the tumor and improved the overall anti- I/II UV1 synthetic
Prostate cancer peptide vaccine
and GMCSF

6

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

Table 3. over 5 years [82]. The pancreatic cancer cells are also distinguished by
several germline or genetic mutations including KRAS (90%), TP53
Lymphoma (75%–90%), CDK2NA (90%), SMAD4/DPC4 (50%). Surgical resection is
a possible treatment for this type of cancer, however, primarily, the
Lymphomas are a biologically and clinically heterogeneous group of cancer goes undetected at an earlier stage and those who opt for surgery
carcinomas that develop in secondary lymphoid organs from mature B- show signs of recurrence within 2 years after operation. The other
or T-lymphocytes [78]. Global statistics reveal Hodgkin lymphoma oc­ treatment strategies include combination chemotherapy, immune
curs in 0.4% of total cancer population, while, non-Hodgkin lymphoma checkpoint inhibitors and targeted therapies. The aggressive nature of
(NHL) is more frequent and accounts for 2.8% of all types of cancer [56]. the tumor cells along with the hostile tumor microenvironment nature
With the increase in the incidence of lymphoma and no known effective has resulted in the chemoresistance [83]. Hence, the target of recent
treatment, there is an urgent need to develop novel therapies [79]. Pa­ clinical investigations have been shifted to newer therapies such as
tients with lymphoma have been benefitted from monoclonal antibodies macrophage and cytotoxic T-lymphocyte targeted therapies, adoptive T-
such as rituximab, however, majority of patients remain incurable or die cell therapy and cancer vaccines [84]. Designing a pancreatic cancer
of the disease [79]. The identification of B-cell receptor variable regions vaccine based on peptide, tumor cell, dendritic cell or DNA based system
as B-NHL unique antigens aided the development of tailored made has several disadvantages leading to poor therapeutic efficacy [85–88].
vaccines to protect patients against their own tumors. Despite promising On the contrary, mRNA cannot incorporate into the genome and hence
early results, this technique has yet to demonstrate enough clinical value does not pose any risk of insertional mutagenesis, with a superior safety
to gain regulatory approval [80]. Use of personalized and standardized profile. Nonetheless, mRNA vaccine against pancreatic cancer antigens
approach have been tested earlier, but have experienced drawbacks, has remained underdeveloped so far, and no suitable patient population
with slim chance of success in clinical trials. Further, tumor-induced has been identified. A recent study by Huang et al, identified 6 potential
immunosuppressive factors and immune regulatory mechanism might antigens, namely, WNT7A, ADAM9, MET, EFNB2, TPX2 and TMOD3 for
limit the ability of immune system to generate antitumor immune mRNA vaccine development [89]. Patients with immune subtypes 4 and
response. Currently, the mRNA vaccine approaches are mostly in the 5 considered as immunological “cold” phenotypes were found to be
nascent stage with preclinical studies demonstrating promising efficacy suitable for vaccination [89]. A list of clinical trials for the development
in reducing tumor growth. As mentioned earlier in the paragraph for of pancreatic cancer vaccine is reported in Table 5.
prostate cancer, the co-delivery of C16-R848 adjuvant-pulsed mRNA
vaccination with OVA RNA significantly reduced tumor growth in syn­ Melanoma
geneic allograft mouse models of lymphoma [77]. Similarly, in another
study, 6 female C57BL mice were subcutaneously injected with E.G7 Melanoma is a malignant tumor that originates from melanocytes,
OVA expressing lymphoma cells to test the therapeutic efficacy of mRNA with a 5-year survival rate of 10% in patients with end-stage melanoma
Galsomes over NPs containing unmodified mRNA. After intravenous [90]. Nowadays, several therapies are available, including chemo­
administration, mRNA Galsomes transmits nucleoside-modified anti­ therapy, radiation therapy, immunotherapy, and surgery. Of these,
gen-encoding mRNA as well as the glycolipid antigen and immunopo­ immunotherapy with ipilimumab, nivolumab and pembrolizumab have
tentiator α-galactosyl ceramide to APCs. Both the treatments showed been approved as standard therapy for cutaneous melanoma. Chemo­
significant tumor reduction in 40% of animals and prolonged OS. therapeutic treatment regimens damage the normally dividing cells
Further combination of mRNA Galsomes with PD-L1 checkpoint inhib­ along with tumor-infected cells [91]. Hence, the process of development
itor indicated a synergistic behavior in tumor reduction [81]. The clin­ of further treatment strategies which suppress tumor growth is being
ical trials related to mRNA vaccine in lymphoma is listed in Table 4. explored. mRNA based vaccines are the latest development for treat­
ment of melanoma. An initial phase I/II trial in 21 metastatic melanoma
Pancreatic cancer patients co-injected with protamine-protected mRNA induced antitumor
Pancreatic cancer is a fatal malignancy with survival rate of 10.8% immune response. Especially in patients injected with keyhole limpet
hemocyanin (KLH) along with vaccine, the frequency of Foxp3+/CD4+
Table 4 regulatory T cells decreased upon mRNA vaccination in their peripheral
Clinical trials for lymphoma. blood, whereas myeloid suppressor cells (CD11b + HLA-DRlo mono­
cytes) were reduced in the patients not receiving KLH [92]. A recent
Conditions NCT Number Phases Interventions Status application of personalized RNA mutanomes in 5 humans demonstrated
Phase Individual peptide Active, not
Primary/ NCT03559413 I/II vaccination with recruiting Table 5
Relapsed Acute NCT04969601 adjuvant GM-CSF Recruiting Clinical trials for pancreatic cancer.
Lymphoblastic Phase and Imiquimod
Leukemia NCT03739931 I/II Vaccine Recruiting Conditions NCT Number Study Interventions Status
NCT03323398 COMIRNATYAˆ ® design Recruiting
Acute Leukemia/ NCT04847050 Phase (BNT162b2) Active, not Autologous DC vaccine Recruiting
Acute I recruiting Pancreatic NCT04157127 Phase I
Lymphoblastic mRNA-2752/ Cancer Nivolumab/ Recruiting
Leukemia/ Phase Durvalumab Recruiting NCT05116917 Phase Ipilimumab/Influenza
Acute Myeloid I/II Pancreatic II vaccine/Stereotactic Active, not
Leukemia mRNA-2752/ Cancer body radiation therapy recruiting
Phase Durvalumab Autologous Dendritic Active, not
Relapsed/ II Pancreatic NCT04627246 Phase I Cell Vaccine Loaded recruiting
Refractory mRNA-1273 Cancer with Personalized
Solid Tumor Peptides (PEP-DC
Malignancies Pancreatic NCT03948763 Phase I vaccine)
or Lymphoma Cancer NCT04161755 Phase I V941/Pembrolizumab

Relapsed/ Pancreatic Atezolizumab/
Refractory Cancer RO7198457/
Solid Tumor mFOLFIRINOX
Malignancies
or Lymphoma

Lymphoma

7

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

prolonged progression-free survival. Two of the five patients experi­ Table 6
enced vaccine-related objective responses, while 1 patient had a late Clinical trials for melanoma.
relapse suggesting acquired resistance mechanism. The third patient
develop complete response to vaccination in combination with PD-1 Conditions NCT Number Study Interventions Status
blockade therapy [40]. Another preclinical study in C57BL/6 mouse design
model of B16F10 melanoma reported the promising immune response of Melanoma NCT02410733 Phase Tetravalent RNA- Active, not
lipid encapsulated mRNA vaccine encoding TRP2. In addition, co- I lipoplex cancer recruiting
delivery of mRNA vaccine and PD-L1 siRNA downregulated PD-L1 in Metastatic NCT00672542 vaccine targeting 4
the dendritic cells promoting T cell activation and proliferation, in turn Melanoma Phase TAAs (RBL001.1, Completed
inhibiting tumor growth and metastasis [93]. Various combinations of I RBL002.2,
mRNA with ICIs are currently being explored in clinical trials. For Melanoma NCT01684241 RBL003.1, and Completed
instance, Wilgenhof et al. assessed the anti-tumor activity of TriMixDC- Melanoma NCT04526899 Phase RBL004.1 Recruiting
MEL (an autologous monocyte-derived dendritic cell electroporated Melanoma NCT00126685 I Proteasome siRNA Unknown
with synthetic mRNA encoding CD40 ligand) in patients with pretreated Phase and tumor antigen
advanced melanoma, either as a monotherapy (NCT01066390) or Melanoma NCT01456104 II RNA-transfected Active, not
combined with ipilimumab (NCT01302496) and in disease free mela­ Melanoma NCT05264974 Phase dendritic cells recruiting
noma patients following local treatment of macro metastases. The me­ I/II RBL001/RBL002 Not yet
dian progression-free survival and overall survival was substantially Melanoma NCT02035956 recruiting
improved in both the groups with more durable increase in patients with NCT01216436 Phase BNT111/ Completed
combination therapy [94]. An interim analysis by Sahin et al. showed Metastatic I Cemiplimab Terminated
that BNT111 alone or in combination with PD1 inhibitors, mediates Melanoma NCT00074230 Phase autologous tumor Completed
durable objective responses in checkpoint-inhibitor experienced pa­ I cell vaccine/
tients with unresectable melanoma. These responses were accompanied Melanoma therapeutic Completed
by strong induction of CD4+ and CD8 + T cell immunity against the Phase autologous
vaccine antigens [45]. A list of clinical trials for the development of Melanoma NCT01676779 I dendritic cells Terminated
melanoma vaccine is reported in Table 6. Phase Langerhans-type Completed
Resected NCT03394937 I dendritic cells
Several clinical investigations for mRNA vaccines in various type of melanoma NCT01066390 Autologous total
cancer have reported promising preliminary results. A list of clinical Phase tumor mRNA
trials along with their results are presented in Table 7. Stage III/IV NCT01302496 I/II loaded DOTAP
Malignant liposome vaccine
Optimization of the mRNA vaccine pharmaceutical features Melanoma NCT00204516 Phase Ivac mutanome,
I/II rbl001/rbl002
Vaccine design and modification Stage III/IV NCT01278940 RNA-transfected
Malignant Phase mature autologous
The development of cancer vaccine depends on type of cancer, vac­ Melanoma NCT03815058 I DC
cine design and its modification and route of delivery (Fig. 3). The NCT03897881 Phase Autologous
mRNA vaccine is presented under 2 categories: self-amplifying RNA Malignant NCT02285413 I Dendritic Cells
(saRNA) and nonreplicating mRNA. The typical non-replicating mRNA Melanoma NCT00204607 loaded with MAGE-
comprises of a cap, flanked by 5′-untranslated regions (UTR) and 3′- NCT00961844 Phase A3, MelanA and
UTRs, open reading frame (ORF) encoding vaccine antigens and poly(A) Advanced NCT01530698 II Survivin
tail. Similar to conventional mRNA vaccine, mRNA is prepared syn­ Malignant NCT00243529 mRNA
thetically by in vitro transcription of a linearized plasmid DNA or PCR Melanoma Phase Electroporated
construct containing the targeted gene and a promoter region when NCT00978913 I/II Autologous
bacteriophage polymerase binds and initiates synthesis [95]. While the Advanced Dendritic Cells
saRNA is more complex and comprises of the coding sequences of a viral Melanoma Phase ECI-006
replicase complex, a genomic and a sub genomic promoter, along with I/II
the basic elements of a conventional mRNA molecule. The change of High-Risk TriMixDC
mRNA’s non-coding regions (5′ cap structure and capping efficiency, 5′- Melanoma Phase
and 3′ UTRs), 3′ poly(A) tail), and nucleoside base modifications are all II TriMix-DC and Completed
part of the optimization process. Melanoma Phase ipilimumab
II
Codon optimization Melanoma Phase mRNA coding for Completed
II melanoma Completed
Translation efficiency is known to be influenced by codon compo­ Metastatic Phase associated antigens
sition. The rate of protein production and the time spent in the ribosome melanoma I/II Dendritic Cells
repository can be affected by mRNA sequence codon optimization [96]. Phase loaded RNA
It was discovered that replacing a nucleotide with N1-methyl- Melanoma I/II
pseudouridine (N1mΨ) improves base pair stability, resulting in a Phase RO719845/ Active, not
complex secondary structure and better mRNA translation [96]. Melanoma I/II Pembrolizumab recruiting
Substituting rare codons with regular identical codons that contain Stage III or Phase mRNA-4157/ Active, not
plenty of similar tRNA in the cytosol is a common practice to alleviate IV I/II pembrolizumab recruiting
mRNA production [97]. Although a high GC sequence may cause DC based mRNA/ Completed
problems with mRNA secondary structure, it translates 100-fold higher Breast Cancer Phase cisplatin
than a low GC sequence [98]. or I mRNA Completed
Malignant
Melanoma Tumor-derived Terminated
mRNA/Temolomide Completed
Autologous Completed
dendritric mRNA
Autologous
dendritric mRNA

DC mRNA Completed

(continued on next page)

8

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

Table 6 (continued ) reactogenicity of SAM vaccines may be difficult [33]. The applications of
SAM in cancer vaccine development are however limited to animal
Conditions NCT Number Study Interventions Status models, and 2 clinical trials against colorectal cancers (NCT01890213
design and NCT00529984).
Melanoma NCT00940004 DC mRNA Completed
NCT03480152 Phase NCI-4650 Terminated Delivery format
Melanoma NCT01973322 I/II DC mRNA Recruiting Due to negatively charged structure of naked RNA and large mo­
Phase
Stage III/IV I/II lecular size, mRNA is prone to nuclease degradation and cannot cross
malignant Phase the cell membrane. Thus to overcome this obstacle, several mRNA
melanoma II vaccine delivery strategies have been employed such as, naked mRNA
delivery, mRNA delivery through viral vectors, polymer-based vectors,
Noncoding region optimization lipid-based vectors, lipid-polymer hybrid nanoparticles, and peptide-
based vectors [4,111], Subcutaneous administration has been found
The 5ʹ and 3ʹ UTR elements bordering the coding sequence have very efficient for translation of encoded protein for mRNA, with the
significant impact on the stability and translation of mRNA, both of ability to induce both cellular and immune response through this route.
which are crucial considerations in the optimal vaccine design. These However, the outermost layer of skin represents a tough barrier for
optimization increases the efficiency and half-life of mRNA [99,100]. drugs absorption and hence various approaches have been adopted to
For effective mRNA protein synthesis, a 5ʹ cap structure is essential overcome this barrier, including microneedles, microporation, and jet
[101]. This can be achieved by applying 5ʹ cap in multiple versions injection, electroporation, iontophoresis, sonophoresis, formulation as
during or after the transcription process by using a vaccinia virus NPs and liposomes [112].
capping enzyme [102] or by incorporating synthetic cap or anti-reverse
cap analogues [103]. An appropriate length of poly(A) tail also plays a Lipid-based vectors/nanoparticles
critical role in regulation of mRNA translation and stability, thus it must
be inserted directly from the encoding DNA template or with poly(A) The LNPs are derived from cationic lipids containing tertiary or
polymerase [104]. A recent study suggested that mRNAs with phos­ quaternary amines to encapsulate polyanionic mRNA. A study reported
phorothioate groups within the poly(A) tail were less sensitive to 3′- antigen-specific CTL activity and suppressed the OVA-suppressing tu­
deadenylase degradation than unmodified mRNA and were more effi­ mors in mice injected with OVA-encoding mRNA in 1,2-dioleoyl-3-tri­
ciently produced in cultured cells, paving the way for future progress of methylammonium-propane (DOTAP) and/or DOPE liposomes [113].
mRNA-based therapeutics [105]. Coadministration of the mRNA for GM-CSF increased OVA-specific
cytolytic responses in the same research. Another study found that
Modifications of untranslated regions of mRNA also represents one of subcutaneous distribution of LNP-formulated mRNA expressing two
the approaches to enhance both mRNA efficiency and stability. Warren melanoma-associated antigens inhibited tumor growth in mice, and that
et al. used a synthetic 5′ UTR with a strong Kozak translation signal and co-delivery of lipopolysaccharide (LPS) in LNPs boosted CTL and anti­
the alpha globin 3′UTR to increase protein synthesis during fibroblast tumor activity [114]. A study by Kranz et al. [115] reported that mRNA-
conversion to induced pluripotent stem cells [106]. Elsewhere, the lipoplexes encoded with DOTMA/DOPE lipids were able to protect
globin 3′UTR has been used to increase mRNA stability since globin antigen-encoding mRNA against extracellular ribonucleases, which
mRNAs generate large amount of protein with longer half-life [99]. accumulated in the spleen and successfully delivered the mRNA into DCs
Recently, in a review article by Miao et al. suggested 3 steps for modi­ following systemic treatment, leading in the development of an antigen-
fication of UTR as: “avoid the presence of start codon (AUG), and non- specific immune response. A preclinical study in mice injected with
canonical start codons (CUG) in the 5′ UTR, second, avoid the pres­ antibody-encoding mRNA delivery showed promising response against
ence of highly stable secondary structures, which can prevent ribosome cancer [116]. Similarly, another study on mice inoculated with lucif­
recruitment and codon recognition. Thirdly, shorter 5’UTR may be erase expressing Raji lymphoma cells and treated with mRNA-LNP
introduced as previous studies have shown that this type of 5’UTR is encoding rituximab revealed diminished tumor growth, underscoring
more conducive to mRNA translation process” [17]. A screening method the importance of mRNA coated antibodies as a viable therapeutic op­
using a diverse set of 5′UTR and 3′UTR combinations for better tion for treatment of cancer [117]. In general, mRNA cancer vaccines
expression of the Arginase 1 protein highlighted 5′ UTR as an essential have shown to be immunogenic in people, but further improvement of
driver in protein expression for exogenously delivered mRNA [107]. vaccination methods based on fundamental immunological studies will
almost certainly be required to gain higher clinical effects.
Elimination of pathogen-associated molecular patterns in mRNA via
incorporation of modified nucleosides, such as pseudouridine [108] and Polymer-based vectors
1-methylpseudouridine (m1Ψ) [109], and fast protein liquid chroma­
tography purification to remove double-stranded RNA contaminants Polymeric materials though are less clinically investigated than
[110] is another approach to improve mRNA therapeutic efficiency. An ionizable lipids, they coat mRNA without the hassles of self-degradation
advantage of such optimization is that the vaccine is able to bypass the and also promote protein expression. The drawback of polymeric ma­
transcription process directly starting the translation phase to produce terials however are polydispersity and the clearance of large molecules
the immunogenic protein inside the human cells [33]. [91]. To improve the stability of the polymeric platforms, structural
modifications such as lipid chains, expansion of branch structures and
Self-amplification vaccine construction of biodegradation-promoting domains is considered [118].
A polyethyleneimine-polyplex nanoparticle carrying mRNA expressing
Self-amplifying mRNA (SAM) vaccines are derived from an α-virus the influenza virus hemagglutinin and nucleocapsid was employed in a
genome, which enables the intact RNA replication but the structural research of mRNA vaccinations. mRNA was successfully transported to
protein genes substituted with the antigen of interest. Due to intracel­ dendritic cells, transferred to the cytosol, and translated into proteins in
lular replication of the antigen-encoding RNA, the SAM can produce a this study, resulting in both humoral and cellular immunological re­
significant amount of antigen from a very little vaccination dose [33]. sponses [119]. However, because extremely positively charged
SAM vaccines are capable of creating their own complements of dsRNA polyethylene-based formulations attach to negatively charged serum
structures, replicate intermediates and other features which could proteins, they are more hazardous; as a result, new cationic polymers,
contribute to their high effectiveness. However, due to the inherent
nature of these RNAs, modulating the inflammatory profile or

9

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

Table 7
Summary of clinical trials for mRNA vaccine and their results in various cancers.

Interventions Conditions Results NCT Number Sponsor Study
BioNTech SE design
VAC_W_bre1_uID/ Breast Cancer iNeST IVAC_M_uID is highly efficient in NCT02316457 Phase I
IVAC_M_uID inducing strong poly-epitopic T-cell NCT03739931 ModernaTX, Inc.
responses in patients with TNBC in the Phase I
mRNA-2752/Durvalumab Relapsed/Refractory Solid Tumor post-(neo) adjuvant setting
CV9103 Malignancies or Lymphoma/ Triple Tumor regressions was observed in
Negative Breast Cancer, HNSCC, Non- approximately 50% of patients with head
Hodgkin’s, Urothelial Cancer, Immune and neck cancer with mRNA 2752 and
Checkpoint Refractory Melanoma, and durvalumab
NSCLC Lymphoma
Hormonal The two-component mRNA vaccine NCT00831467/ CureVac AG Phase
Refractory Prostate mediates a strong antitumor response NCT00923312 I/II
Cancer against OVA-expressing tumor cells, not
only in a prophylactic but also in a NCT01197625
Dendritic cell vaccine Prostate Cancer therapeutic setting NCT01817738 Oslo University Hospital Phase
CV9104 mCRPC Adjuvant DCV mitigates the time to NCT01446731 CureVac AG I/II
Autologous dendritic cell mCRPC biochemical progression NCT02692976 Inge Marie Svane Phase
CV9104 exhibited antigen-specific I/II
immune responses post vaccination NCT04382898 Phase
Adjuvant therapy with autologous NCT00004211 II
dendritic cell vaccine provided longer
mDC and pDC vaccination mCRPC median PFS and DSS NCT02410733 Radboud University Phase
Blood-derived CD1c+ myeloid dendritic Medical Center II
cells induced functional antigen-specific T NCT00672542
BNT112 and cemiplimab Prostate cancer cells which in turn is correlated with an BioNTech SE Phase
improved clinical outcome. NCT01456104 I/II
PSA Prostate cancer BNT112 induces immune and PSA Duke University,
RNA-pulsed Melanoma responses in patients with advanced NCT02035956 National Cancer Phase
dendritic cell prostate cancer. Institute I/II
vaccine Escalating doses of PSA mRNA-transfected NCT00074230
DCs were administered with no evidence BioNTech SE Phase I
Lipo-MERIT of dose-limiting toxicity or adverse effects, NCT01676779
including autoimmunity. NCT03394937
Proteasome siRNA and Metastatic melanoma Lipo-MERIT vaccine is a potent NCT01066390 Scott Pruitt Phase I
tumor antigen RNA- Melanoma immunotherapy in patients with CPI-
transfected dendritic experienced melanoma, and induced NCT01302496 Memorial Sloan Phase I
cells strong CD4+ and CD8 + T cell immunity NCT02285413 Kettering Cancer Center,
against the vaccine antigens Rockefeller University
Langerhans-type dendritic Tumor antigen-loaded DCs provided NCT00204607
cells electroporated partial clinical response, exhibited diffuse
with TRP-2 mRNA dermal and soft tissue metastases, had a
complete response.
IVAC MUTANOME, Melanoma TRP2 mRNA-electroporated LC vaccines BioNTech RNA Phase I
RBL001/RBL002 produced antigen-specific responses Pharmaceuticals GmbH
especially in terms of cytokine secretion,
Autologous Dendritic Stage IV melanoma cytolytic degranulation, and increased University Hospital Phase
Cells loaded with TCR clonality leading to clinical outcomes. Erlangen I/II
MAGE-A3, MelanA and Stage III/IV melanoma 60% of the 125 selected neo-epitopes
Survivin Melanoma elicited a T-cell response. No severe Universitair Ziekenhuis Phase
Melanoma adverse drug reactions were reported Brussel, RIZIV II
TriMixDC-MEL Vaccination with IVAC® MUTANOME was eTheRNA Phase I
very well tolerated. immunotherapies
ECI-006 Few patients achieved full remission and/ Bart Neyns Phase I
or survived for >10 years, while 2 patients
TriMix-DC developed asymptomatic sarcoidosis after
treatment with autologous dendritic cells
TriMix-DC and Stage III/IV melanoma TriMixDC-MEL is tolerable and results in a Bart Neyns, Vrije Phase
ipilimumab Stage III/IV melanoma high rate of durable tumor responses Universiteit Brussel II
Malignant melanoma ECI-006 was generally well tolerated and
Dendritic cells with or demonstrated immunogenic response Radboud University Phase
without cisplation TriMixDC-MEL was safe and produced Medical Center II
immunogenic response. Durable
mRNA with GM-CSF antitumor activity was observed across the University Hospital Phase
investigated iv dose levels Tuebingen I/II
TriMixDC provided robust CD8 + T-cell
responses in melanoma patients, and in
patients with a clinical response
Combination therapy of DC vaccine and
cisplatin is safe and produces immune
response but the clinical response is
similar to DC vaccine monotherapy
Direct injection of protamine-protected
mRNA is feasible and safe.

(continued on next page)

10

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405
Table 7 (continued )
Conditions Results NCT Number Sponsor Study
Interventions ModernaTX, Inc. design
mRNA-2416 Relapsed/Refractory Solid Tumor mRNA-2416 was well-tolerated at all dose NCT03323398 Phase
Malignancies or Lymphoma,Ovarian levels. Analyses of tumor post-treatment Inge Marie Svane I/II
Dendritic vaccine Cancer demonstrate increased OX40L protein NCT00978913 National Cancer
NCI-4650 expression, elevated PD-L1 levels and pro- NCT03480152 Institute Phase I
Breast cancer and malignant melanoma inflammatory activity.
Treatment with autologous DCs mRNA Phase
Melanoma, Colon Cancer, Gastrointestinal was feasible and safe and did not alter the I/II
Cancer, Genitourinary Cancer, percentage of Tregs in patients
Hepatocellular Cancer NCI-4650 was found to be safe and elicited
mutation-specific T cell responses

Fig. 3. Key elements that affect mRNA vaccine stability and translation efficacy. LNP – lipid nanoparticles, RNA – ribonucleic acid, UTR – untranslated region.

such as poly(2-dimethylaminoethyl methacrylate) have been created better or it is the best route [4]. In short, the route of administration is
[120]. Polymer-based delivery system research is still in the early stages significant in determining the efficacy of mRNA vaccine [111].
of development.
Both naked and lipid-formulated mRNA administered subcutane­
Route of delivery ously cause cell transfection, with naked mRNA surpassing lipid-
formulated mRNA in terms of translational efficiency. Both formats
Researchers have investigated various methods for delivery of mRNA have demonstrated to induce antigen-specific T cells, but neither has
vaccines. For instance, mRNA vaccines can be delivered via lipid- or been shown to transfect nodal cells [121,122]. In contrast, a study using
polymer-based system. Dendritic cells can be delivered ex-vivo and lipid nano formulations (approx.70–100 nm) found high and long-
transferred to the hosts. Targeting of mRNA efficiently into DCs via in lasting translation at the injection site, as well as in CD11c+ cells in
vivo route remains a major issue. When it comes to solving the delivery draining lymph nodes, leading to delayed tumor growth [114]. Kreiter
problem, there are two key variables to consider: delivery route (the et al. found that intranodal delivery of adjusted naked antigen-encoding
route/portals of entry into the body) and delivery format (stabilized, mRNA elicited effective antitumor immunity and mRNA was internal­
naked, encapsulated, complexed, adsorbed, etc.). Each delivery route ized and translated via micropinocytosis by lymph node resident con­
(intradermal, intra tumoral, intranodal, intravenous, subcutaneous, ventional and cross-presenting CD8a + DCs [121]. Another study by
intranasal) has its own set of challenges to overcome, and these chal­ Thielemans et al. validated the potency of intranodal delivery and
lenges will decide the best delivery method. In other words, while format in additional tumor models [123]. Thielemans et al. pioneered
developing a vaccine design, the underlying motivation should be a intertumoral administration to DCs. When in vivo transfected with Tri­
reasonable combination of delivery route and format. Obtaining Mix, their findings show that naked mRNA is mostly picked up by cross-
adequate immunological responses with a certain format and distribu­ presenting CD8a + DCs, and that these cells can reawaken T cells at the
tion route does not necessarily imply that particular delivery route is tumor site as well as move to the draining lymph. The mRNA-encoded
secreted proteins might relieve part of the load on immune cells by

11

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

lowering MDSC repression, boosting DCs, and activating T cell lysis, infectious diseases and malignancies.
which improved tumor growth delay when paired with PD-1 inhibition Author contributions
[123]. All authors contributed to manuscript conception, preparation, and

Future perspectives and conclusion approved the final version of the manuscript for submission.

With the development and global approval of mRNA vaccines against Declaration of Competing Interest
SARS-CoV-2 virus in the last year have outscored the potential of mRNA
technology. Most patients with cancer are non-responsive to current The authors declare that they have no known competing financial
immunotherapies, frequently patients experience relapse and subse­ interests or personal relationships that could have appeared to influence
quently toxicities to therapies. In this context, therapeutic cancer vac­ the work reported in this paper.
cines is an appealing option to immunotherapy setting because of their
potential for safety, specificity, and long-term response due to immu­ Acknowledgments
nological memory stimulation [21]. The favorable features of potency,
fast and relative low-cost production of mRNA vaccine provide an The authors acknowledge Anwesha Mandal and Dr. Amit Bhat of
attractive platform for cancer therapy. The mRNA cancer vaccine can be Indegene Pvt Ltd. For their medical writing and editorial support.
a preferred combination agent with currently available therapies for
long-term cancer treatment considering the favorable safety profile Funding
observed to date.
This research did not receive any specific grant from funding
Apart from recent progress in the lipid-based delivery system for agencies in the public, commercial, or not-for-profit sectors. Medical
mRNA vaccines, chimeric antigen receptor (CAR)-T cell immunotherapy writing and editorial support were funded by Shanghai Fosun Pharma­
is emerging as an encouraging treatment approach for treating malig­ ceutical Industrial Development, Co., Ltd.
nancies. CAR-T therapy is a personalized form of cell therapy where
patient-T cells are genetically engineered to express receptors allowing References
them to recognize tumor antigens. The adoptive transfer of genetically
modified T cells for expressing a CAR have shown encouraging response [1] Orenstein WA, Ahmed R. Simply put: vaccination saves lives. Proc Natl Acad Sci
against hematological tumors. Given this approach, mRNA electropo­ USA 2017;114:4031–3. https://doi.org/10.1073/pnas.1704507114.
ration has been utilized to generate T cells with CAR expression in
preclinical trials [124,125] and subsequently in human trials [126,127]. [2] Pollard AJ, Bijker EM. A guide to vaccinology: from basic principles to new
The preclinical data showed that Descartes-08, an autologous CD8 + developments. Nat Rev Immunol 2021;21:83–100. https://doi.org/10.1038/
CAR T therapy inhibits development of BCMA CAR-specific myeloma s41577-020-00479-7.
and substantially prolongs host survival. Furthermore, an ongoing
clinical trial of Descartes-08 reported a favorable therapeutic index with [3] Chandler M, Johnson MB, Panigaj M, Afonin KA. Innate immune responses
durable responses upon preliminary analysis in patients with relapsed/ triggered by nucleic acids inspire the design of immunomodulatory nucleic acid
refractory myeloma (NCT03448978), thus providing a framework for nanoparticles (NANPs). Curr Opin Biotechnol 2020;63:8–15. https://doi.org/
another study using Descartes-11 which is an optimized or humanized 10.1016/j.copbio.2019.10.011.
version of Descartes-08 in patients with newly diagnosed myeloma pa­
tients and having residual disease after induction therapy [128]. [4] Grunwitz C, Kranz LM. mRNA cancer vaccines-messages that prevail. Curr Top
Microbiol Immunol 2017;405:145–64. https://doi.org/10.1007/82_2017_509.
Future research should concentrate on deciphering the immunolog­
ical pathways triggered by different mRNA vaccine platforms and [5] Suschak JJ, Williams JA, Schmaljohn CS. Advancements in DNA vaccine vectors,
attempt to improve current techniques based on these mechanisms. non-mechanical delivery methods, and molecular adjuvants to increase
Utilizing immune-gene therapy with the transfection of autologous immunogenicity. Hum Vaccin Immunother 2017;13:2837–48. https://doi.org/
mRNA vaccine is another upcoming approach which deserves explora­ 10.1080/21645515.2017.1330236.
tion. For instance, a phase I/II study is currently underway to determine
the efficacy and safety of ELI-002, a lipid-conjugated immune-stim­ [6] Commissioner O of the COVID-19 Vaccines. FDA; 2021.
ulatory oligonucleotide (Amph-CpG-7909) as an adjuvant therapy with [7] Baden Lindsey R, El Sahly Hana M, Essink Brandon, Kotloff Karen, Frey Sharon,
a mixture of lipid- conjugated peptide-based antigens (Amph-Peptides)
for minimally residual disease in patients with KRAS/neuroblastoma Novak Rick, et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine.
Ras viral oncogene homolog mutated pancreatic cancer or other solid N Engl J Med 2021;384(5):403–16.
tumors (NCT04853017). [8] Chu Laurence, McPhee Roderick, Huang Wenmei, Bennett Hamilton,
Pajon Rolando, Nestorova Biliana, et al. A preliminary report of a randomized
To conclude, despite multifaceted challenges remain in the devel­ controlled phase 2 trial of the safety and immunogenicity of mRNA-1273 SARS-
opment of mRNA vaccines, such as extremely large size, susceptibility to CoV-2 vaccine. Vaccine 2021;39(20):2791–9.
enzymatic degradation and instability, the durable efficacy of the RNA [9] Ali Kashif, Berman Gary, Zhou Honghong, Deng Weiping, Faughnan Veronica,
in various stages of clinical trials deserves consideration. The work of Coronado-Voges Maria, et al. Evaluation of mRNA-1273 SARS-CoV-2 vaccine in
mRNA on other types of cancer such as ovarian cancer, gastrointestinal adolescents. N Engl J Med 2021;385(24):2241–51.
cancer remains to be explored. However, delivering mRNA to specific [10] Polack Fernando P, Thomas Stephen J, Kitchin Nicholas, Absalon Judith,
organs, tissues, or cell types remains a significant challenge in the area. Gurtman Alejandra, Lockhart Stephen, et al. Safety and efficacy of the BNT162b2
It is thus necessary to identify the validated biomarkers that can predict mRNA Covid-19 vaccine. N Engl J Med 2020;383(27):2603–15.
mRNA vaccine efficacy and be utilized for further optimization of the [11] Olson Samantha M, Newhams Margaret M, Halasa Natasha B, Price Ashley M,
vaccine. Additionally, combination therapies of mRNA with immune Boom Julie A, Sahni Leila C, et al. Effectiveness of BNT162b2 vaccine against
checkpoint inhibitors and other immunosuppressing drugs are showing critical Covid-19 in adolescents. N Engl J Med 2022;386(8):713–23.
promise [129], nevertheless, more research is needed to determine the [12] Tsai H-J. Clinical cancer chemoprevention: from the hepatitis B virus (HBV)
most effective combinations and the optimal drug dose for each vaccine to the human papillomavirus (HPV) vaccine. Taiwanese J Obstet Gynecol
component. mRNA vaccines will become a significant class of medicine 2015;54:112–5. https://doi.org/10.1016/j.tjog.2013.11.009.
as delivery technologies and vaccine formulations improve, allowing [13] Cancer Vaccines: Preventive, Therapeutic, Personalized. Cancer Research
them to effectively combat a variety of health conditions such as Institute n.d. <https://www.cancerresearch.org/en-us/immunotherapy/
treatment-types/cancer-vaccines> [accessed December 29, 2021].
[14] Cheever MA, Higano CS. PROVENGE (Sipuleucel-T) in prostate cancer: the first
FDA-approved therapeutic cancer vaccine. Clin Cancer Res 2011;17:3520–6.
https://doi.org/10.1158/1078-0432.CCR-10-3126.
[15] Morales A. BCG: a throwback from the stone age of vaccines opened the path for
bladder cancer immunotherapy. Can J Urol 2017;24:8788–93.
[16] FDA approves first oncolytic virus therapy: imlygic for melanoma. Oncol Times
2015;37:36. <https://doi.org/10.1097/01.COT.0000475724.97729.9e>.
[17] Miao L, Zhang Y, Huang L. mRNA vaccine for cancer immunotherapy. Mol Cancer
2021;20:41. https://doi.org/10.1186/s12943-021-01335-5.
[18] Wang Y, Zhang Z, Luo J, Han X, Wei Y, Wei X. mRNA vaccine: a potential
therapeutic strategy. Mol Cancer 2021;20:33. https://doi.org/10.1186/s12943-
021-01311-z.
[19] Maruggi G, Zhang C, Li J, Ulmer JB, Yu D. mRNA as a transformative technology
for vaccine development to control infectious diseases. Mol Ther 2019;27:
757–72. https://doi.org/10.1016/j.ymthe.2019.01.020.

12

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

[20] Le DT, Pardoll DM, Jaffee EM. Cellular vaccine approaches. Cancer J 2010;16: [44] Definition of tetravalent RNA-lipoplex cancer vaccine BNT111 – NCI Drug
304–10. https://doi.org/10.1097/PPO.0b013e3181eb33d7. Dictionary – National Cancer Institute; 2011. <https://www.cancer.gov/
publications/dictionaries/cancer-drug/def/tetravalent-rna-lipoplex-cancer-
[21] Hollingsworth RE, Jansen K. Turning the corner on therapeutic cancer vaccines. vaccine-bnt111> [accessed January 5, 2022].
NPJ Vacc 2019;4:7. https://doi.org/10.1038/s41541-019-0103-y.
[45] Sahin Ugur, Oehm Petra, Derhovanessian Evelyna, Jabulowsky Robert A,
[22] Eric Lutz, Yeo Charles J, Lillemoe Keith D, Biedrzycki Barbara, Kobrin Barry, Vormehr Mathias, Gold Maike, et al. An RNA vaccine drives immunity in
Herman Joseph, et al. A lethally irradiated allogeneic granulocyte-macrophage checkpoint-inhibitor-treated melanoma. Nature 2020;585(7823):107–12.
colony stimulating factor-secreting tumor vaccine for pancreatic
adenocarcinoma. A Phase II trial of safety, efficacy, and immune activation. Ann [46] BioNTech SE. Open-label, Randomized Phase II Trial With BNT111 and
Surg 2011;253(2):328–35. Cemiplimab in Combination or as Single Agents in Patients With Anti-PD-1-
refractory/Relapsed, Unresectable Stage III or IV Melanoma. clinicaltrials.gov;
[23] Jaffee Elizabeth M, Hruban Ralph H, Biedrzycki Barbara, Laheru Daniel, 2021.
Schepers Karen, Sauter Patricia R, et al. Novel allogeneic granulocyte-
macrophage colony-stimulating factor-secreting tumor vaccine for pancreatic [47] Definition of mRNA-derived KRAS-targeted vaccine V941 – NCI Drug Dictionary –
cancer: a phase I trial of safety and immune activation. J Clin Oncol 2001;19(1): National Cancer Institute; 2011. <https://www.cancer.gov/publications/
145–56. dictionaries/cancer-drug/def/mrna-derived-kras-targeted-vaccine-v941>
[accessed January 13, 2022].
[24] Beyaert S, Machiels J-P, Schmitz S. Vaccine-based immunotherapy for head and
neck cancers. Cancers (Basel) 2021;13:6041. https://doi.org/10.3390/ [48] Moderna, Inc. – SEC.gov n.d. <https://www.sec.gov/Archives/edgar/data/
cancers13236041. 1682852/000168285219000009/moderna10-k12312018.htm> [accessed
January 13, 2022].
[25] Bezu Lucillia, Kepp Oliver, Cerrato Giulia, Pol Jonathan, Fucikova Jitka,
Spisek Radek, et al. Trial watch: peptide-based vaccines in anticancer therapy. [49] Mougel A, Terme M, Tanchot C. Therapeutic cancer vaccine and combinations
Oncoimmunology 2018;7(12):e1511506. with antiangiogenic therapies and immune checkpoint blockade. Front Immunol
2019;10:467. https://doi.org/10.3389/fimmu.2019.00467.
[26] Yang B, Jeang J, Yang A, Wu TC, Hung C-F. DNA vaccine for cancer
immunotherapy. Hum Vaccin Immunother 2015;10:3153–64. https://doi.org/ [50] Kongsted Per, Borch Troels Holz, Ellebaek Eva, Iversen Trine Zeeberg,
10.4161/21645515.2014.980686. Andersen Rikke, Met O¨ zcan, et al. Dendritic cell vaccination in combination with
docetaxel for patients with metastatic castration-resistant prostate cancer: A
[27] Boczkowski D, Nair SK, Snyder D, Gilboa E. Dendritic cells pulsed with RNA are randomized phase II study. Cytotherapy 2017;19(4):500–13.
potent antigen-presenting cells in vitro and in vivo. J Exp Med 1996;184:465–72.
https://doi.org/10.1084/jem.184.2.465. [51] Sharma P, Allison JP. The future of immune checkpoint therapy. Science 2015;
348:56–61. https://doi.org/10.1126/science.aaa8172.
[28] Aarntzen Erik HJG, Schreibelt Gerty, Bol Kalijn, Lesterhuis W Joost,
Croockewit Alexandra J, de Wilt Johannes HW, et al. Vaccination with mRNA- [52] Fotin-Mleczek M, Zanzinger K, Heidenreich R, Lorenz C, Kowalczyk A, Kallen K-J,
electroporated dendritic cells induces robust tumor antigen-specific CD4+ and et al. mRNA-based vaccines synergize with radiation therapy to eradicate
CD8+ T cells responses in stage III and IV melanoma patients. Clin Cancer Res established tumors. Radiat Oncol 2014;9:180. https://doi.org/10.1186/1748-
2012;18(19):5460–70. 717X-9-180.

[29] Wilgenhof Sofie, Van Nuffel An MT, Corthals Jurgen, Heirman Carlo, [53] Papachristofilou Alexandros, Hipp Madeleine M, Klinkhardt Ute, Früh Martin,
Tuyaerts Sandra, Benteyn Daphne´, et al. Therapeutic vaccination with an Sebastian Martin, Weiss Christian, et al. Phase Ib evaluation of a self-adjuvanted
autologous mRNA electroporated dendritic cell vaccine in patients with advanced protamine formulated mRNA-based active cancer immunotherapy, BI1361849
melanoma. J Immunother 2011;34(5):448–56. (CV9202), combined with local radiation treatment in patients with stage IV non-
small cell lung cancer. J Immunother Cancer 2019;7(1). https://doi.org/
[30] Coosemans A, Vanderstraeten A, Tuyaerts S, Verschuere T, Moerman P, 10.1186/s40425-019-0520-5.
Berneman Z, et al. Immunological response after WT1 mRNA-loaded dendritic
cell immunotherapy in ovarian carcinoma and carcinosarcoma. Anticancer Res [54] Liu Lina, Wang Yuhua, Miao Lei, Liu Qi, Musetti Sara, Li Jun, et al. Combination
2013;33:3855–9. immunotherapy of MUC1 mRNA nano-vaccine and CTLA-4 blockade effectively
inhibits growth of triple negative breast cancer. Mol Ther 2018;26(1):45–55.
[31] Vik-Mo Einar Osland, Nyakas Marta, Mikkelsen Birthe Viftrup, Moe Morten
Carstens, Due-Tønnesen Paulina, Suso Else Marit Inderberg, et al. Therapeutic [55] Zhang C, Maruggi G, Shan H, Li J. Advances in mRNA vaccines for infectious
vaccination against autologous cancer stem cells with mRNA-transfected diseases. Front Immunol 2019;10:594. https://doi.org/10.3389/
dendritic cells in patients with glioblastoma. Cancer Immunol Immunother 2013; fimmu.2019.00594.
62(9):1499–509.
[56] Sung Hyuna, Ferlay Jacques, Siegel Rebecca L, Laversanne Mathieu,
[32] Beck JD, Reidenbach D, Salomon N, Sahin U, Türeci O¨ , Vormehr M, et al. mRNA Soerjomataram Isabelle, Jemal Ahmedin, et al. Global cancer statistics 2020:
therapeutics in cancer immunotherapy. Mol Cancer 2021;20:69. https://doi.org/ GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185
10.1186/s12943-021-01348-0. countries. CA Cancer J Clin 2021;71(3):209–49.

[33] Pardi N, Hogan MJ, Porter FW, Weissman D. mRNA vaccines — a new era in [57] Street W. Breast Cancer Facts & Figures 2019–2020 n.d.:44.
vaccinology. Nat Rev Drug Discov 2018;17:261–79. https://doi.org/10.1038/ [58] Breast cancer n.d. <https://www.who.int/news-room/fact-sheets/detail/breast-
nrd.2017.243.
cancer> [accessed December 31, 2021].
[34] Pedersen SR, Sørensen MR, Buus S, Christensen JP, Thomsen AR. Comparison of [59] Iglesia Michael D, Parker Joel S, Hoadley Katherine A, Serody Jonathan S,
vaccine-induced effector CD8 T cell responses directed against self- and non-self-
tumor antigens: implications for cancer immunotherapy. J Immunol 2013;191: Perou Charles M, Vincent Benjamin G. Genomic analysis of immune cell
3955–67. https://doi.org/10.4049/jimmunol.1300555. infiltrates across 11 tumor types. J Natl Cancer Inst 2016;108(11):djw144.
[60] Shah D, Osipo C. Cancer stem cells and HER2 positive breast cancer: the story so
[35] Carreno BM, Magrini V, Becker-Hapak M, Kaabinejadian S, Hundal J, Petti AA, far. Genes Dis 2016;3:114–23. https://doi.org/10.1016/j.gendis.2016.02.002.
et al. Cancer immunotherapy. A dendritic cell vaccine increases the breadth and [61] Burke EE, Kodumudi K, Ramamoorthi G, Czerniecki BJ. Vaccine therapies for
diversity of melanoma neoantigen-specific T cells. Science 2015;348(6236): breast cancer. Surg Oncol Clin N Am 2019;28:353–67. https://doi.org/10.1016/j.
803–8. soc.2019.02.004.
[62] Mittendorf EA, Ardavanis A, Symanowski J, Murray JL, Shumway NM, Litton JK,
[36] Ott Patrick A, Hu Zhuting, Keskin Derin B, Shukla Sachet A, Sun Jing, et al. Primary analysis of a prospective, randomized, single-blinded phase II trial
Bozym David J, et al. An immunogenic personal neoantigen vaccine for patients evaluating the HER2 peptide AE37 vaccine in breast cancer patients to prevent
with melanoma. Nature 2017;547(7662):217–21. recurrence. Ann Oncol 2016;27(7):1241–8.
[63] Peoples George E, Gurney Jennifer M, Hueman Matthew T, Woll Mike M,
[37] Gjerstorff Morten F, Andersen Mads H, Ditzel Henrik J. Oncogenic cancer/testis Ryan Gayle B, Storrer Catherine E, et al. Clinical trial results of a HER2/neu (E75)
antigens: prime candidates for immunotherapy. Oncotarget 2015;6(18): vaccine to prevent recurrence in high-risk breast cancer patients. J Clin Oncol
15772–87. 2005;23(30):7536–45.
[64] Disis Mary L, Wallace Danelle R, Gooley Theodore A, Dang Yushe, Slota Meredith,
[38] Rosenberg SA, Yang JC, Restifo NP. Cancer immunotherapy: moving beyond Lu Hailing, et al. Concurrent trastuzumab and HER2/neu-specific vaccination in
current vaccines. Nat Med 2004;10:909–15. https://doi.org/10.1038/nm1100. patients with metastatic breast cancer. J Clin Oncol 2009;27(28):4685–92.
[65] Schmidt M, Heimes A-S. Immunomodulating therapies in breast cancer—from
[39] Kreiter Sebastian, Vormehr Mathias, van de Roemer Niels, Diken Mustafa, prognosis to clinical practice. Cancers (Basel) 2021;13:4883. https://doi.org/
Lo¨wer Martin, Diekmann Jan, et al. Mutant MHC class II epitopes drive 10.3390/cancers13194883.
therapeutic immune responses to cancer. Nature 2015;520(7549):692–6. [66] Schmidt M, Bolte S, Frenzel K, Heesen L, Derhovanessian E, Bukur V, et al.
Abstract OT2-06-01: Highly innovative personalized RNA-immunotherapy for
[40] Sahin Ugur, Derhovanessian Evelyna, Miller Matthias, Kloke Bjo¨rn-Philipp, patients with triple negative breast cancer. Cancer Res 2019;79:OT2-06.
Simon Petra, Lo¨wer Martin, et al. Personalized RNA mutanome vaccines mobilize <https://doi.org/10.1158/1538-7445.SABCS18-OT2-06-01>.
poly-specific therapeutic immunity against cancer. Nature 2017;547(7662): [67] Schmidt M, Vogler I, Derhovanessian E, Omokoko T, Godehardt E, Attig S, et al.
222–6. 88MO T-cell responses induced by an individualized neoantigen specific immune
therapy in post (neo)adjuvant patients with triple negative breast cancer. Ann
[41] Cafri Gal, Gartner Jared J, Zaks Tal, Hopson Kristen, Levin Noam, Paria Biman C, Oncol 2020;31:S276.
et al. mRNA vaccine-induced neoantigen-specific T cell immunity in patients with [68] Sebastian Martin, Schro¨der Andreas, Scheel Birgit, Hong Henoch S, Muth Anke,
gastrointestinal cancer. J Clin Invest 2020;130(11):5976–88. von Boehmer Lotta, et al. A phase I/IIa study of the mRNA-based cancer
immunotherapy CV9201 in patients with stage IIIB/IV non-small cell lung cancer.
[42] Burris Howard A, Patel Manish R, Cho Daniel C, Clarke Jeffrey Melson, Cancer Immunol Immunother 2019;68(5):799–812.
Gutierrez Martin, Zaks Tal Z, et al. A phase I multicenter study to assess the
safety, tolerability, and immunogenicity of mRNA-4157 alone in patients with
resected solid tumors and in combination with pembrolizumab in patients with
unresectable solid tumors. JCO 2019;37(15_suppl):2523.

[43] Lopez JS, Camidge R, Iafolla M, Rottey S, Schuler M, Hellmann M, et al. Abstract
CT301: a phase Ib study to evaluate RO7198457, an individualized Neoantigen
Specific immunoTherapy (iNeST), in combination with atezolizumab in patients
with locally advanced or metastatic solid tumors. Cancer Res 2020;80:
CT301–CT301. <https://doi.org/10.1158/1538-7445.AM2020-CT301>.

13

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

[69] Rausch S, Schwentner C, Stenzl A, Bedke J. mRNA vaccine CV9103 and CV9104 J Immunother Cancer 2015;3:P211. https://doi.org/10.1186/2051-1426-3-S2-
for the treatment of prostate cancer. Hum Vaccin Immunother 2014;10:3146–52. P211.
https://doi.org/10.4161/hv.29553. [95] Minnaert An-Katrien, Vanluchene Helena, Verbeke Rein, Lentacker Ine, De
Smedt Stefaan C, Raemdonck Koen, et al. Strategies for controlling the innate
[70] Kallen Karl-Josef, Heidenreich Regina, Schnee Margit, Petsch Benjamin, immune activity of conventional and self-amplifying mRNA therapeutics: Getting
Schlake Thomas, Thess Andreas, et al. A novel, disruptive vaccination technology: the message across. Adv Drug Deliv Rev 2021;176:113900.
self-adjuvanted RNActive(®) vaccines. Hum Vaccin Immunother 2013;9(10): [96] Mauger David M, Cabral B Joseph, Presnyak Vladimir, Su Stephen V, Reid David
2263–76. W, Goodman Brooke, et al. mRNA structure regulates protein expression through
changes in functional half-life. PNAS 2019;116(48):24075–83.
[71] Kübler H, Maurer T, Stenzl A, Feyerabend S, Steiner U, Schostak M, et al. Final [97] Cannarozzi Gina, Schraudolph Nicol N, Faty Mahamadou, von Rohr Peter,
analysis of a phase I/IIa study with CV9103, an intradermally administered Friberg Markus T, Roth Alexander C, et al. A role for codon order in translation
prostate cancer immunotherapy based on self-adjuvanted mRNA. JCO 2011;29 dynamics. Cell 2010;141(2):355–67.
(15_suppl):4535. [98] Kudla Grzegorz, Lipinski Leszek, Caffin Fanny, Helwak Aleksandra, Zylicz Maciej,
Hurst Laurence D. High guanine and cytosine content increases mRNA levels in
[72] Stenzl A, Feyerabend S, Syndikus I, Sarosiek T, Kübler H, Heidenreich A, et al. mammalian cells. PLoS Biol 2006;4(6):e180.
Results of the randomized, placebo-controlled phase I/IIB trial of CV9104, an [99] Ross J, Sullivan TD. Half-lives of beta and gamma globin messenger RNAs and of
mRNA based cancer immunotherapy, in patients with metastatic castration- protein synthetic capacity in cultured human reticulocytes. Blood 1985;66:
resistant prostate cancer (mCRPC). Ann Oncol 2017;28:v408–9. 1149–54.
[100] Holtkamp Silke, Kreiter Sebastian, Selmi Abderraouf, Simon Petra,
[73] Zhou W-Z, Hoon DSB, Huang SKS, Fujii S, Hashimoto K, Morishita R, et al. RNA Koslowski Michael, Huber Christoph, et al. Modification of antigen-encoding RNA
melanoma vaccine: induction of antitumor immunity by human glycoprotein 100 increases stability, translational efficacy, and T-cell stimulatory capacity of
mRNA immunization. Hum Gene Ther 1999;10(16):2719–24. dendritic cells. Blood 2006;108(13):4009–17.
[101] Gallie DR. The cap and poly(A) tail function synergistically to regulate mRNA
[74] Mockey M, Bourseau E, Chandrashekhar V, Chaudhuri A, Lafosse S, Le Cam E, translational efficiency. Genes Dev 1991;5:2108–16. https://doi.org/10.1101/
et al. mRNA-based cancer vaccine: prevention of B16 melanoma progression and gad.5.11.2108.
metastasis by systemic injection of MART1 mRNA histidylated lipopolyplexes. [102] Muttach F, Muthmann N, Rentmeister A. Synthetic mRNA capping. Beilstein J Org
Cancer Gene Ther 2007;14(9):802–14. Chem 2017;13:2819–32. https://doi.org/10.3762/bjoc.13.274.
[103] Kocmik Ilona, Piecyk Karolina, Rudzinska Magdalena, Niedzwiecka Anna,
[75] Fu Y, Li J. A novel delivery platform based on Bacteriophage MS2 virus-like Darzynkiewicz Edward, Grzela Renata, et al. Modified ARCA analogs providing
particles. Virus Res 2016;211:9–16. https://doi.org/10.1016/j. enhanced translational properties of capped mRNAs. Cell Cycle 2018;17(13):
virusres.2015.08.022. 1624–36.
[104] Jalkanen AL, Coleman SJ, Wilusz J. Determinants and implications of mRNA Poly
[76] Li J, Sun Y, Jia T, Zhang R, Zhang K, Wang L. Messenger RNA vaccine based on (A) tail size – does this protein make my tail look big? Semin Cell Dev Biol 2014:
recombinant MS2 virus-like particles against prostate cancer. Int J Cancer 2014; 24–32. https://doi.org/10.1016/j.semcdb.2014.05.018.
134:1683–94. https://doi.org/10.1002/ijc.28482. [105] Strzelecka D, Smietanski M, Sikorski PJ, Warminski M, Kowalska J, Jemielity J.
Phosphodiester modifications in mRNA poly(A) tail prevent deadenylation
[77] Islam Mohammad Ariful, Rice Jamie, Reesor Emma, Zope Harshal, Tao Wei, without compromising protein expression. RNA 2020;26:1815–37. https://doi.
Lim Michael, et al. Adjuvant-pulsed mRNA vaccine nanoparticle for org/10.1261/rna.077099.120.
immunoprophylactic and therapeutic tumor suppression in mice. Biomaterials [106] Warren Luigi, Manos Philip D, Ahfeldt Tim, Loh Yuin-Han, Li Hu, Lau Frank, et al.
2021;266:120431. Highly efficient reprogramming to pluripotency and directed differentiation of
human cells with synthetic modified mRNA. Cell Stem Cell 2010;7(5):618–30.
[78] Zappasodi R, de Braud F, Di Nicola M. Lymphoma immunotherapy: current [107] Asrani KH, Farelli JD, Stahley MR, Miller RL, Cheng CJ, Subramanian RR, et al.
status. Front Immunol 2015;6:448. https://doi.org/10.3389/fimmu.2015.00448. Optimization of mRNA untranslated regions for improved expression of
therapeutic mRNA. RNA Biol 2018;15:756–62. https://doi.org/10.1080/
[79] Pierpont TM, Limper CB, Richards KL. Past, present, and future of rituximab-the 15476286.2018.1450054.
world’s first oncology monoclonal antibody therapy. Front Oncol 2018;8:163. [108] Kariko´ Katalin, Muramatsu Hiromi, Welsh Frank A, Ludwig Ja´nos, Kato Hiroki,
https://doi.org/10.3389/fonc.2018.00163. Akira Shizuo, et al. Incorporation of pseudouridine into mRNA yields superior
nonimmunogenic vector with increased translational capacity and biological
[80] Brody J, Levy R. Lymphoma immunotherapy: vaccines, adoptive cell transfer and stability. Mol Ther 2008;16(11):1833–40.
immunotransplant. Immunotherapy 2009;1:809–24. https://doi.org/10.2217/ [109] Andries O, Mc Cafferty S, De Smedt SC, Weiss R, Sanders NN, Kitada T. N(1)-
imt.09.50. methylpseudouridine-incorporated mRNA outperforms pseudouridine-
incorporated mRNA by providing enhanced protein expression and reduced
[81] Verbeke R, Lentacker I, Breckpot K, Janssens J, Van Calenbergh S, De Smedt SC, immunogenicity in mammalian cell lines and mice. J Control Release 2015;217:
et al. Broadening the message: a nanovaccine co-loaded with messenger RNA and 337–44. https://doi.org/10.1016/j.jconrel.2015.08.051.
α-GalCer induces antitumor immunity through conventional and natural killer T [110] Kariko´ Katalin, Muramatsu Hiromi, Ludwig Ja´nos, Weissman Drew. Generating
cells. ACS Nano 2019;13:1655–69. https://doi.org/10.1021/acsnano.8b07660. the optimal mRNA for therapy: HPLC purification eliminates immune activation
and improves translation of nucleoside-modified, protein-encoding mRNA. Nucl
[82] Cancer of the Pancreas – Cancer Stat Facts. SEER n.d. <https://seer.cancer.gov/ Acids Res 2011;39(21):e142.
statfacts/html/pancreas.html> [accessed January 3, 2022]. [111] Zeng C, Zhang C, Walker PG, Dong Y. Formulation and Delivery Technologies for
mRNA Vaccines, Berlin, Heidelberg: Springer; n.d., p. 1–40. <https://doi.org/
[83] Feig C, Gopinathan A, Neesse A, Chan DS, Cook N, Tuveson DA. The pancreas 10.1007/82_2020_217>.
cancer microenvironment. Clin Cancer Res 2012;18:4266–76. https://doi.org/ [112] Wadhwa A, Aljabbari A, Lokras A, Foged C, Thakur A. Opportunities and
10.1158/1078-0432.CCR-11-3114. challenges in the delivery of mRNA-based vaccines. Pharmaceutics 2020;12:102.
https://doi.org/10.3390/pharmaceutics12020102.
[84] Chiorean EG, Coveler AL. Pancreatic cancer: optimizing treatment options, new, [113] Hess PR, Boczkowski D, Nair SK, Snyder D, Gilboa E. Vaccination with mRNAs
and emerging targeted therapies. Drug Des Devel Ther 2015;9:3529–45. https:// encoding tumor-associated antigens and granulocyte-macrophage colony-
doi.org/10.2147/DDDT.S60328. stimulating factor efficiently primes CTL responses, but is insufficient to
overcome tolerance to a model tumor/self antigen. Cancer Immunol Immunother
[85] Gjertsen Marianne K, Buanes Trond, Rosseland Arne R, Bakka Arne, 2006;55:672–83. https://doi.org/10.1007/s00262-005-0064-z.
Gladhaug Ivar, Soreide Odd, et al. Intradermal ras peptide vaccination with [114] Oberli Matthias A, Reichmuth Andreas M, Dorkin J Robert, Mitchell Michael J,
granulocyte-macrophage colony-stimulating factor as adjuvant: Clinical and Fenton Owen S, Jaklenec Ana, et al. Lipid nanoparticle assisted mRNA delivery
immunological responses in patients with pancreatic adenocarcinoma. Int J for potent cancer immunotherapy. Nano Lett 2017;17(3):1326–35.
Cancer 2001;92(3):441–50. [115] Kranz Lena M, Diken Mustafa, Haas Heinrich, Kreiter Sebastian, Loquai Carmen,
Reuter Kerstin C, et al. Systemic RNA delivery to dendritic cells exploits antiviral
[86] Bernhardt SL, Gjertsen MK, Trachsel S, Møller M, Eriksen JA, Meo M, et al. defence for cancer immunotherapy. Nature 2016;534(7607):396–401.
Telomerase peptide vaccination of patients with non-resectable pancreatic [116] Stadler Christiane R, Ba¨hr-Mahmud Hayat, Celik Leyla, Hebich Bernhard,
cancer: a dose escalating phase I/II study. Br J Cancer 2006;95(11):1474–82. Roth Alexandra S, Roth Ren´e P, et al. Elimination of large tumors in mice by
mRNA-encoded bispecific antibodies. Nat Med 2017;23(7):815–7.
[87] Le Dung T, Lutz Eric, Uram Jennifer N, Sugar Elizabeth A, Onners Beth, Solt Sara, [117] Thran Moritz, Mukherjee Jean, Po¨nisch Marion, Fiedler Katja, Thess Andreas,
et al. Evaluation of ipilimumab in combination with allogeneic pancreatic tumor Mui Barbara L, et al. mRNA mediates passive vaccination against infectious
cells transfected with a GM-CSF gene in previously treated pancreatic cancer. agents, toxins, and tumors. EMBO Mol Med 2017;9(10):1434–47.
J Immunother 2013;36(7):382–9. [118] Kaczmarek James C, Patel Asha K, Kauffman Kevin J, Fenton Owen S,
Webber Matthew J, Heartlein Michael W, et al. Polymer-lipid nanoparticles for
[88] Le Dung T, Wang-Gillam Andrea, Picozzi Vincent, Greten Tim F, Crocenzi Todd, systemic delivery of mRNA to the lungs. Angew Chem Int Ed Engl 2016;55(44):
Springett Gregory, et al. Safety and survival with GVAX pancreas prime and 13808–12.
Listeria Monocytogenes-expressing mesothelin (CRS-207) boost vaccines for
metastatic pancreatic cancer. J Clin Oncol 2015;33(12):1325–33.

[89] Huang X, Zhang G, Tang T, Liang T. Identification of tumor antigens and immune
subtypes of pancreatic adenocarcinoma for mRNA vaccine development. Mol
Cancer 2021;20:44. https://doi.org/10.1186/s12943-021-01310-0.

[90] Heistein JB, Acharya U. Malignant Melanoma. StatPearls Publishing; 2021.
[91] Bidram Maryam, Zhao Yue, Shebardina Natalia G, Baldin Alexey V,

Bazhin Alexandr V, Ganjalikhany Mohamad Reza, et al. mRNA-based cancer
vaccines: a therapeutic strategy for the treatment of melanoma patients. Vaccines
(Basel) 2021;9(10):1060.
[92] Weide Benjamin, Pascolo Steve, Scheel Birgit, Derhovanessian Evelyna,
Pflugfelder Annette, Eigentler Thomas K, et al. Direct injection of protamine-
protected mRNA: results of a phase 1/2 vaccination trial in metastatic melanoma
patients. J Immunother 2009;32(5):498–507.
[93] Wang Y, Zhang L, Xu Z, Miao L, Huang L. mRNA vaccine with antigen-specific
checkpoint blockade induces an enhanced immune response against established
melanoma. Mol Ther 2018;26:420–34. https://doi.org/10.1016/j.
ymthe.2017.11.009.
[94] Wilgenhof S, Corthals J, Heirman C, Neyns B, Thielemans K. Clinical trials with
MRNA electroporated dendritic cells for stage III/IV melanoma patients.

14

J. Wei and A.-M. Hui Cancer Treatment Reviews 107 (2022) 102405

[119] D´emoulins Thomas, Milona Panagiota, Englezou Pavlos C, Ebensen Thomas, [125] Barrett DM, Liu X, Jiang S, June CH, Grupp SA, Zhao Y. Regimen-specific effects
Schulze Kai, Suter Rolf, et al. Polyethylenimine-based polyplex delivery of self- of RNA-modified chimeric antigen receptor T cells in mice with advanced
replicating RNA vaccines. Nanomedicine 2016;12(3):711–22. leukemia. Hum Gene Ther 2013;24:717–27. https://doi.org/10.1089/
hum.2013.075.
[120] Üzgün Senta, Nica Gabriela, Pfeifer Corinna, Bosinco Michele, Michaelis Kai,
Lutz Jean-François, et al. PEGylation improves nanoparticle formation and [126] Beatty Gregory L, Haas Andrew R, Maus Marcela V, Torigian Drew A,
transfection efficiency of messenger RNA. Pharm Res 2011;28(9):2223–32. Soulen Michael C, Plesa Gabriela, et al. Mesothelin-specific chimeric antigen
receptor mRNA-engineered T cells induce anti-tumor activity in solid
[121] Kreiter Sebastian, Selmi Abderraouf, Diken Mustafa, Koslowski Michael, malignancies. Cancer Immunol Res 2014;2(2):112–20.
Britten Cedrik M, Huber Christoph, et al. Intranodal vaccination with naked
antigen-encoding RNA elicits potent prophylactic and therapeutic antitumoral [127] Bai Yun, Kan Shifeng, Zhou Shixin, Wang Yuting, Xu Jun, Cooke John P, et al.
immunity. Cancer Res 2010;70(22):9031–40. Enhancement of the in vivo persistence and antitumor efficacy of CD19 chimeric
antigen receptor T cells through the delivery of modified TERT mRNA. Cell Discov
[122] Phua KKL, Leong KW, Nair SK. Transfection efficiency and transgene expression 2015;1(1). https://doi.org/10.1038/celldisc.2015.40.
kinetics of mRNA delivered in naked and nanoparticle format. J Control Release
2013;166:227–33. https://doi.org/10.1016/j.jconrel.2012.12.029. [128] Lin Liang, Cho Shih-Feng, Xing Lijie, Wen Kenneth, Li Yuyin, Yu Tengteng, et al.
Preclinical evaluation of CD8+ anti-BCMA mRNA CAR T-cells for treatment of
[123] Van Lint Sandra, Goyvaerts Cleo, Maenhout Sarah, Goethals Lode, Disy Aur´elie, multiple myeloma. Leukemia 2021;35(3):752–63.
Benteyn Daphne´, et al. Preclinical evaluation of TriMix and antigen mRNA-based
antitumor therapy. Cancer Res 2012;72(7):1661–71. [129] De Keersmaecker Brenda, Claerhout Sofie, Carrasco Javier, Bar Isabelle,
Corthals Jurgen, Wilgenhof Sofie, et al. TriMix and tumor antigen mRNA
[124] Zhao Yangbing, Moon Edmund, Carpenito Carmine, Paulos Chrystal M, electroporated dendritic cell vaccination plus ipilimumab: link between T-cell
Liu Xiaojun, Brennan Andrea L, et al. Multiple injections of electroporated activation and clinical responses in advanced melanoma. J Immunother Cancer
autologous T cells expressing a chimeric antigen receptor mediate regression of 2020;8(1):e000329.
human disseminated tumor. Cancer Res 2010;70(22):9053–61.

15