The ability to control autoreactive T cells without inducing systemic immune suppression is the major goal for treatment of autoimmune diseases. The key challenge is the safe and efficient delivery ...of pharmaceutically well-defined antigens in a noninflammatory context. Here, we show that systemic delivery of nanoparticle-formulated 1 methylpseudouridine-modified messenger RNA (m1Ψ mRNA) coding for disease-related autoantigens results in antigen presentation on splenic CD11c
antigen-presenting cells in the absence of costimulatory signals. In several mouse models of multiple sclerosis, the disease is suppressed by treatment with such m1Ψ mRNA. The treatment effect is associated with a reduction of effector T cells and the development of regulatory T cell (T
cell) populations. Notably, these T
cells execute strong bystander immunosuppression and thus improve disease induced by cognate and noncognate autoantigens.
Synthetic mRNA provides a template for the synthesis of any given protein, protein fragment or peptide and lends itself to a broad range of pharmaceutical applications, including different modalities ...of cancer immunotherapy. With the ease of rapid, large scale Good Manufacturing Practice-grade mRNA production, mRNA is ideally poised not only for off-the shelf cancer vaccines but also for personalized neoantigen vaccination. The ability to stimulate pattern recognition receptors and thus an anti-viral type of innate immune response equips mRNA-based vaccines with inherent adjuvanticity. Nucleoside modification and elimination of double-stranded RNA can reduce the immunomodulatory activity of mRNA and increase and prolong protein production. In combination with nanoparticle-based formulations that increase transfection efficiency and facilitate lymphatic system targeting, nucleoside-modified mRNA enables efficient delivery of cytokines, costimulatory receptors, or therapeutic antibodies. Steady but transient production of the encoded bioactive molecule from the mRNA template can improve the pharmacokinetic, pharmacodynamic and safety properties as compared to the respective recombinant proteins. This may be harnessed for applications that benefit from a higher level of expression control, such as chimeric antigen receptor (CAR)-modified adoptive T-cell therapies. This review highlights the advancements in the field of mRNA-based cancer therapeutics, providing insights into key preclinical developments and the evolving clinical landscape.
Synthetic mRNA has emerged as a powerful tool for the transfer of genetic information, and it is being explored for a variety of therapeutic applications. Many of these applications require prolonged ...intracellular persistence of mRNA to improve bioavailability of the encoded protein. mRNA molecules are intrinsically unstable and their intracellular kinetics depend on the UTRs embracing the coding sequence, in particular the 3′ UTR elements. We describe here a novel and generally applicable cell-based selection process for the identification of 3′ UTRs that augment the expression of proteins encoded by synthetic mRNA. Moreover, we show, for two applications of mRNA therapeutics, namely, (1) the delivery of vaccine antigens in order to mount T cell immune responses and (2) the introduction of reprogramming factors into differentiated cells in order to induce pluripotency, that mRNAs tagged with the 3′ UTR elements discovered in this study outperform those with commonly used 3′ UTRs. This approach further leverages the utility of mRNA as a gene therapy drug format.
Orlandini von Niessen et al. describe a cell-based selection process for the identification of 3′ UTRs that augment the expression of proteins encoded by synthetic mRNA. They show in two examples of mRNA application that the discovered 3′ UTRs outperform commonly used regions. These findings leverage the utility of mRNA as a gene therapy drug format.
Treating patients who have cancer with vaccines that stimulate a targeted immune response is conceptually appealing, but cancer vaccine trials have not been successful in late-stage patients with ...treatment-refractory tumours
. We are testing melanoma FixVac (BNT111)-an intravenously administered liposomal RNA (RNA-LPX) vaccine, which targets four non-mutated, tumour-associated antigens that are prevalent in melanoma-in an ongoing, first-in-human, dose-escalation phase I trial in patients with advanced melanoma (Lipo-MERIT trial, ClinicalTrials.gov identifier NCT02410733). We report here data from an exploratory interim analysis that show that melanoma FixVac, alone or in combination with blockade of the checkpoint inhibitor PD1, mediates durable objective responses in checkpoint-inhibitor (CPI)-experienced patients with unresectable melanoma. Clinical responses are accompanied by the induction of strong CD4
and CD8
T cell immunity against the vaccine antigens. The antigen-specific cytotoxic T-cell responses in some responders reach magnitudes typically reported for adoptive T-cell therapy, and are durable. Our findings indicate that RNA-LPX vaccination is a potent immunotherapy in patients with CPI-experienced melanoma, and suggest the general utility of non-mutant shared tumour antigens as targets for cancer vaccination.
An effective vaccine is needed to halt the spread of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. Recently, we reported safety, tolerability and antibody response data ...from an ongoing placebo-controlled, observer-blinded phase I/II coronavirus disease 2019 (COVID-19) vaccine trial with BNT162b1, a lipid nanoparticle-formulated nucleoside-modified mRNA that encodes the receptor binding domain (RBD) ofthe SARS-CoV-2 spike protein1. Here we present antibody and T cell responses after vaccination with BNT162b1 from a second, non-randomized open-label phase I/II trial in healthy adults, 18-55 years of age. Two doses of 1-50 pg ofBNT162b1 elicited robust CD4+ and CD8+ T cell responses and strong antibody responses, with RBD-binding IgG concentrations clearly above those seen in serum from a cohort of individuals who had recovered from COVID-19. Geometric mean titres of SARS-CoV-2 serum-neutralizing antibodies on day 43 were 0.7-fold (1-pg dose) to 3.5-fold (50-pg dose) those of the recovered individuals. Immune sera broadly neutralized pseudoviruses with diverse SARS-CoV-2 spike variants. Most participants had T helper type 1 (TH1)-skewed T cell immune responses with RBD-specific CD8+ and CD4+ T cell expansion. interferon-у was produced by a large fraction ofRBD-specific CD8+ and CD4+ T cells. The robust RBD-specific antibody, T cell and favourable cytokine responses induced by the BNT162b1 mRNA vaccine suggest that it has the potential to protect against COVID-19 through multiple beneficial mechanisms.
Lymphoid organs, in which antigen presenting cells (APCs) are in close proximity to T cells, are the ideal microenvironment for efficient priming and amplification of T-cell responses. However, the ...systemic delivery of vaccine antigens into dendritic cells (DCs) is hampered by various technical challenges. Here we show that DCs can be targeted precisely and effectively in vivo using intravenously administered RNA-lipoplexes (RNA-LPX) based on well-known lipid carriers by optimally adjusting net charge, without the need for functionalization of particles with molecular ligands. The LPX protects RNA from extracellular ribonucleases and mediates its efficient uptake and expression of the encoded antigen by DC populations and macrophages in various lymphoid compartments. RNA-LPX triggers interferon-α (IFNα) release by plasmacytoid DCs and macrophages. Consequently, DC maturation in situ and inflammatory immune mechanisms reminiscent of those in the early systemic phase of viral infection are activated. We show that RNA-LPX encoding viral or mutant neo-antigens or endogenous self-antigens induce strong effector and memory T-cell responses, and mediate potent IFNα-dependent rejection of progressive tumours. A phase I dose-escalation trial testing RNA-LPX that encode shared tumour antigens is ongoing. In the first three melanoma patients treated at a low-dose level, IFNα and strong antigen-specific T-cell responses were induced, supporting the identified mode of action and potency. As any polypeptide-based antigen can be encoded as RNA, RNA-LPX represent a universally applicable vaccine class for systemic DC targeting and synchronized induction of both highly potent adaptive as well as type-I-IFN-mediated innate immune mechanisms for cancer immunotherapy.
The development of nucleic acid based vaccines against cancer has gained considerable momentum through the advancement of modern sequencing technologies and on novel RNA-based synthetic drug formats, ...which can be readily adapted following identification of every patient's tumor-specific mutations. Furthermore, affordable and individual 'on demand' production of molecularly optimized vaccines should allow their application in large groups of patients. This has resulted in the therapeutic concept of an active personalized cancer vaccine, which has been brought into clinical testing. Successful trials have been performed by intranodal administration of sterile isotonic solutions of synthetic RNA vaccines. The second generation of RNA vaccines which is currently being developed encompasses intravenously injectable RNA nanoparticle formulations (lipoplexes), made up from lipid excipients, denoted RNA
. A first product that has made its way from bench to bedside is a therapeutic vaccine for intravenous administration based on a fixed set of four RNA lipoplex drug products, each encoding for one shared tumor antigen (Lipoplex Melanoma RNA Immunotherapy, 'Lipo-MERIT'). This article describes the steps for translating these novel RNA nanomedicines into clinical trials.
BNT162b2, a nucleoside-modified mRNA formulated in lipid nanoparticles that encodes the SARS-CoV-2 spike glycoprotein (S) stabilized in its prefusion conformation, has demonstrated 95% efficacy in ...preventing COVID-19.sup.1. Here we extend a previous phase-I/II trial report.sup.2 by presenting data on the immune response induced by BNT162b2 prime-boost vaccination from an additional phase-I/II trial in healthy adults (18-55 years old). BNT162b2 elicited strong antibody responses: at one week after the boost, SARS-CoV-2 serum geometric mean 50% neutralizing titres were up to 3.3-fold above those observed in samples from individuals who had recovered from COVID-19. Sera elicited by BNT162b2 neutralized 22 pseudoviruses bearing the S of different SARS-CoV-2 variants. Most participants had a strong response of IFNgamma.sup.+ or IL-2.sup.+ CD8.sup.+ and CD4.sup.+ T helper type 1 cells, which was detectable throughout the full observation period of nine weeks following the boost. Using peptide-MHC multimer technology, we identified several BNT162b2-induced epitopes that were presented by frequent MHC alleles and conserved in mutant strains. One week after the boost, epitope-specific CD8.sup.+ T cells of the early-differentiated effector-memory phenotype comprised 0.02-2.92% of total circulating CD8.sup.+ T cells and were detectable (0.01-0.28%) eight weeks later. In summary, BNT162b2 elicits an adaptive humoral and poly-specific cellular immune response against epitopes that are conserved in a broad range of variants, at well-tolerated doses.
mRNA vaccines are finally ready to assume their rightful place at the forefront of nucleic acid- based vaccines. Major achievements within the last two decades have turned this highly versatile ...molecule into a safe and very attractive pharmaceutical platform that combines many positive attributes able to address a broad range of diseases, including cancer. The simplicity of mRNA vaccines greatly reduces complications generally associated with the production of biological vaccines. Intrinsic costimulatory and inflammatory triggers in addition to the provision of the antigenic information makes mRNA an all- in-one molecule that does not need additional adjuvants and that does not pose the risk of genomic integration. Clinical studies in various cancer types are moving forward and promising results with favorable clinical outcome are awaited. This review will recapitulate conceptual, mechanistic and immune-related features of this highly versatile molecule, elucidate how these features have been addressed in the past, and how comprehensive understanding can foster further optimization for broad application possibilities in cancer treatment.
During the last decade, mRNA became increasingly recognized as a versatile tool for the development of new innovative therapeutics. Especially for vaccine development, mRNA is of outstanding interest ...and numerous clinical trials have been initiated. Strikingly, all of these studies have proven that large-scale GMP production of mRNA is feasible and concordantly report a favorable safety profile of mRNA vaccines. Induction of T-cell immunity is a multi-faceted process comprising antigen acquisition, antigen processing and presentation, as well as immune stimulation. The effectiveness of mRNA vaccines is critically dependent on making the antigen(s) of interest available to professional antigen-presenting cells, especially DCs. Efficient delivery of mRNA into DCs in vivo remains a major challenge in the mRNA vaccine field. This review summarizes the principles of mRNA vaccines and highlights the importance of in vivo mRNA delivery and recent advances in harnessing their therapeutic potential.
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