Comprehensive studies on building a scalable downstream process for mRNAs to enable mRNA therapeutics

In recent years, mRNA-based therapeutics have been a fast-growing new class of biologics that can, in principle, encode any protein(s) directly in patients to treat various diseases. mRNA vaccines have been proven to work efficiently, have high potency, and can be rapidly developed and deployed, which is critical for a quick responses in the case of a pandemic. Such agile development is enabled by rapid synthesis of RNA in vitro using recombinant enzymes rather than relying on lengthy and complex cell culture processes. mRNA exhibits physical and chemical properties differing from protein-based therapeutics. It is highly negatively charged and the hydroxyl group makes mRNA less stable and more susceptible to hydrolysis and nucleophilic cleavage. This novel work shares comprehensive studies carried out to compare the performance of various mRNA purification strategies by considering its scalability and critical quality attributes. In addition, the paper provides insights on how to establish a scalable mRNA purification process that consists of ultrafiltration/diafiltration and chromatography steps with good recoveries. Alternative Oligo(dT) based columns were further explored aiming to improve total process recovery. With Oligo(dT) as a capture step, overall recoveries of 70% can be achieved for mRNAs studied here that encode anti-influenza immunoglobulin G monoclonal antibodies.

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

mRNA vaccines have gained popularity over the last decade as a versatile tool for developing novel therapeutics. The recent success of coronavirus disease (COVID-19) mRNA vaccine has unlocked the potential of mRNA technology as a powerful therapeutic platform. In this review, we apprise the literature on the various types of cancer vaccines, the novel platforms available for delivery of the vaccines, the recent progress in the RNA-based therapies and the evolving role of mRNA vaccines for various cancer indications, along with a future strategy to 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 development. 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 combinations 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.

Immunotherapy as a Precision Medicine Tool for the Treatment of Prostate Cancer

Prostate cancer (PCa) is the most frequently diagnosed type of cancer among Caucasian males over the age of 60 and is characterized by remarkable heterogeneity and clinical behavior, ranging from decades of indolence to highly lethal disease. Despite the significant progress in PCa systemic therapy, therapeutic response is usually transient, and invasive disease is associated with high mortality rates. Immunotherapy has emerged as an efficacious and non-toxic treatment alternative that perfectly fits the rationale of precision medicine, as it aims to treat patients on the basis of patient-specific, immune-targeted molecular traits, so as to achieve the maximum clinical benefit. Antibodies acting as immune checkpoint inhibitors and vaccines entailing tumor-specific antigens seem to be the most promising immunotherapeutic strategies in offering a significant survival advantage. Even though patients with localized disease and favorable prognostic characteristics seem to be the ones that markedly benefit from such interventions, there is substantial evidence to suggest that the survival benefit may also be extended to patients with more advanced disease. The identification of biomarkers that can be immunologically targeted in patients with disease progression is potentially amenable in this process and in achieving significant advances in the decision for precision treatment of PCa.

RNA Therapeutics: How Far Have We Gone?

In recent years, the RNA molecule became one of the most promising targets for therapeutic intervention. Currently, a large number of RNA-based therapeutics are being investigated both at the basic research level and in late-stage clinical trials. Some of them are even already approved for treatment. RNA-based approaches can act at pre-mRNA level (by splicing modulation/correction using antisense oligonucleotides or U1snRNA vectors), at mRNA level (inhibiting gene expression by siRNAs and antisense oligonucleotides) or at DNA level (by editing mutated sequences through the use of CRISPR/Cas). Other RNA approaches include the delivery of in vitro transcribed (IVT) mRNA or the use of oligonucleotides aptamers. Here we review these approaches and their translation into clinics trying to give a brief overview also on the difficulties to its application as well as the research that is being done to overcome them.

Biomedical applications of mRNA nanomedicine

As an attractive alternative to plasmid DNA, messenger RNA (mRNA) has recently emerged as a promising class of nucleic acid therapeutics for biomedical applications. Advances in addressing the inherent shortcomings of mRNA and in the development of nanoparticle-based delivery systems have prompted the development and clinical translation of mRNA-based medicines. In this review, we discuss the chemical modification strategies of mRNA to improve its stability, minimize immune responses, and enhance translational efficacy. We also highlight recent progress in nanoparticle-based mRNA delivery. Considerable attention is given to the increasingly widespread applications of mRNA nanomedicine in the biomedical fields of vaccination, protein-replacement therapy, gene editing, and cellular reprogramming and engineering.

Biomaterials for mRNA delivery

Messenger RNA (mRNA) has recently emerged with remarkable potential as an effective alternative to DNA-based therapies because of several unique advantages. mRNA does not require nuclear entry for transfection activity and has a negligible chance of integrating into the host genome which excludes the possibility of potentially detrimental genomic alternations. Chemical modification of mRNA has further enhanced its stability and decreased its activation of innate immune responses. Additionally, mRNA has been found to have rapid expression and predictable kinetics. Nevertheless, the ubiquitous application of mRNA remains challenging given its unfavorable attributes, such as large size, negative charge and susceptibility to enzymatic degradation. Further refinement of mRNA delivery modalities is therefore essential for its development as a therapeutic tool. This review provides an exclusive overview of current state-of-the-art biomaterials and nanotechnology platforms for mRNA delivery, and discusses future prospects to bring these exciting technologies into clinical practice.

Phase Ib study evaluating a self-adjuvanted mRNA cancer vaccine (RNActive®) combined with local radiation as consolidation and maintenance treatment for patients with stage IV non-small cell lung cancer

BACKGROUND

Advanced non-small cell lung cancer (NSCLC) represents a significant unmet medical need. Despite advances with targeted therapies in a small subset of patients, fewer than 20% of patients survive for more than two years after diagnosis. Cancer vaccines are a promising therapeutic approach that offers the potential for durable responses through the engagement of the patient's own immune system. CV9202 is a self-adjuvanting mRNA vaccine that targets six antigens commonly expressed in NSCLC (NY-ESO-1, MAGEC1, MAGEC2, 5 T4, survivin, and MUC1).

METHODS/DESIGN

The trial will assess the safety and tolerability of CV9202 vaccination combined with local radiation designed to enhance immune responses and will include patients with stage IV NSCLC and a response or stable disease after first-line chemotherapy or therapy with an EGFR tyrosine kinase inhibitor. Three histological and molecular subtypes of NSCLC will be investigated (squamous and non-squamous cell with/without EGFR mutations). All patients will receive two initial vaccinations with CV9202 prior to local radiotherapy (5 GY per day for four successive days) followed by further vaccinations until disease progression. The primary endpoint of the study is the number of patients experiencing Grade >3 treatment-related adverse events. Pharmacodynamic analyses include the assessment of immune responses to the antigens encoded by CV9202 and others not included in the panel (antigen spreading) and standard efficacy assessments.

DISCUSSION

RNActive self-adjuvanted mRNA vaccines offer the potential for simultaneously inducing immune responses to a wide panel of antigens commonly expressed in tumors. This trial will assess the feasibility of this approach in combination with local radiotherapy in NSCLC patients.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT01915524/EudraCT No.: 2012-004230-41.

The ReNAissanCe of mRNA-based cancer therapy

About 25 years ago, mRNA became a tool of interest in anticancer vaccination approaches. However, due to its rapid degradation in situ, direct application of mRNA was confronted with considerable skepticism during its early use. Consequently, mRNA was for a long time mainly used for the ex vivo transfection of dendritic cells, professional antigen-presenting cells known to stimulate immunity. The interest in direct application of mRNA experienced a revival, as researchers became aware of the many advantages mRNA offers. Today, mRNA is considered to be an ideal vehicle for the induction of strong immune responses against cancer. The growing numbers of preclinical trials and as a consequence the increasing clinical application of mRNA as an off-the-shelf anticancer vaccine signifies a renaissance for transcript-based antitumor therapy. In this review, we highlight this renaissance using a timeline providing all milestones in the application of mRNA for anticancer vaccination.

Therapeutic vaccines for cancer: an overview of clinical trials

The therapeutic potential of host-specific and tumour-specific immune responses is well recognized and, after many years, active immunotherapies directed at inducing or augmenting these responses are entering clinical practice. Antitumour immunization is a complex, multi-component task, and the optimal combinations of antigens, adjuvants, delivery vehicles and routes of administration are not yet identified. Active immunotherapy must also address the immunosuppressive and tolerogenic mechanisms deployed by tumours. This Review provides an overview of new results from clinical studies of therapeutic cancer vaccines directed against tumour-associated antigens and discusses their implications for the use of active immunotherapy.

A development that may evolve into a revolution in medicine: mRNA as the basis for novel, nucleotide-based vaccines and drugs

Recent advances strongly suggest that mRNA rather than DNA will be the nucleotide basis for a new class of vaccines and drugs. Therapeutic cancer vaccines against a variety of targets have been developed on this basis and initial clinical experience suggests that preclinical activity can be successfully translated to human application. Likewise, prophylactic vaccines against viral pathogens and allergens have demonstrated their activity in animal models. These successes could be extended preclinically to mRNA protein and gene replacement therapy as well as the induction of pluripotent stem cells by mRNA encoded transcription factors. The production of mRNA-based vaccines and drugs is highly flexible, scalable and cost competitive, and eliminates the requirement of a cold chain. mRNA-based drugs and vaccines offer all the advantages of a nucleotide-based approach at reduced costs and represent a truly disruptive technology that may start a revolution in medicine.

Prostate cancer vaccines

In 2010, the US FDA approved the first therapeutic cancer vaccine for the treatment of castration refractory prostate cancer - sipuleucel-T. Prostate cancer is an ideal model for cancer vaccine development based on the ready demonstration of humoral and cellular immunity to a range of cancer antigens as well as often slow progression which means that patients who are otherwise well may have a radiologically evaluable minor progression, after conventional treatment and can undergo vaccine therapy over sufficient periods of time, so as to allow the generation of a robust antitumor response. The association of prostate cancer with one of the few serum cancer biomarkers in general use has also allowed assessment of response and risk stratification of patients. In this review, we will examine key aspects of the evolution of prostate cancer vaccines, which provides an accurate prototype for other cancers, and the challenges we face.

A novel, disruptive vaccination technology: self-adjuvanted RNActive(®) vaccines

Nucleotide based vaccines represent an enticing, novel approach to vaccination. We have developed a novel immunization technology, RNActive^® vaccines, that have two important characteristics: mRNA molecules are used whose protein expression capacity has been enhanced by 4 to 5 orders of magnitude by modifications of the nucleotide sequence with the naturally occurring nucleotides A (adenosine), G (guanosine), C (cytosine), U (uridine) that do not affect the primary amino acid sequence. Second, they are complexed with protamine and thus activate the immune system by involvement of toll-like receptor (TLR) 7. Essentially, this bestows self-adjuvant activity on RNActive^® vaccines. RNActive^® vaccines induce strong, balanced immune responses comprising humoral and cellular responses, effector and memory responses as well as activation of important subpopulations of immune cells, such as Th1 and Th2 cells. Pre-germinal center and germinal center B cells were detected in human patients upon vaccination. RNActive^® vaccines successfully protect against lethal challenges with a variety of different influenza strains in preclinical models. Anti-tumor activity was observed preclinically under therapeutic as well as prophylactic conditions. Initial clinical experiences suggest that the preclinical immunogenicity of RNActive^® could be successfully translated to humans.

Protective efficacy of in vitro synthesized, specific mRNA vaccines against influenza A virus infection

Despite substantial improvements, influenza vaccine production-and availability-remain suboptimal. Influenza vaccines based on mRNA may offer a solution as sequence-matched, clinical-grade material could be produced reliably and rapidly in a scalable process, allowing quick response to the emergence of pandemic strains. Here we show that mRNA vaccines induce balanced, long-lived and protective immunity to influenza A virus infections in even very young and very old mice and that the vaccine remains protective upon thermal stress. This vaccine format elicits B and T cell-dependent protection and targets multiple antigens, including the highly conserved viral nucleoprotein, indicating its usefulness as a cross-protective vaccine. In ferrets and pigs, mRNA vaccines induce immunological correlates of protection and protective effects similar to those of a licensed influenza vaccine in pigs. Thus, mRNA vaccines could address substantial medical need in the area of influenza prophylaxis and the broader realm of anti-infective vaccinology.