Development of mRNA Vaccines/Therapeutics and Their Delivery System

mRNA-based vaccines - global approach, challenges, and could be a promising wayout for future pandemics

mRNA-based vaccines are assured to significantly boost biopharmaceuticals since outbreak of coronavirus disease- 2019. Respiratory infections, such as influenza, SARS, MERS, COVID-19, and respiratory syncytial virus, often have high transmission rates due to their airborne spread. Respiratory infections can lead to severe illness and death. These outbreaks can cause substantial economic and social disruption, as seen with the COVID-19 pandemic. In our interconnected world, respiratory diseases can spread rapidly across borders. mRNA-based vaccines (e.g. mRNA-1283) can reduce the transmission by creating immunity in the population, thus lowering the incidence and spread of these diseases. Vaccines are crucial for global health security, helping to prevent local outbreaks from becoming global pandemics. Nevertheless, various concerns remain such as intracellular delivery, susceptibility to degradation by catalytic hydrolysis, and instability due to several physiological conditions. Therefore, an hour needed to address these challenges and opportunities for attaining high-quality and stable mRNA-based vaccines with novel drug delivery systems. The authors contributed an extensive review of the mRNA-based clinical development, progress in stability, and delivery challenges to mitigate market needs. In addition, the authors discuss crucial advances in the growth of mRNA-based vaccines to date; which dominate an extensive scope of therapeutic implementation. Finally, recent mRNA-based vaccines in clinical trials, adjuvant benefits, and prospects are discussed.

COVID-19 vaccine-associated lymphadenopathy: a review

Following the introduction of RNA-based vaccines, COVID-19 vaccine-associated clinical lymphadenopathy (C19-LAP) has been reported as a side effect. Moreover, subclinical lymphadenopathy detected on imaging (SLDI) has also been observed, mainly as incidental findings while performing screening tests on oncological patients. In these cases, surgical lymphadenectomy, fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB) have been used as a valuable diagnostic tool for SLDI and C19-LAP. In this review the clinical, histologic and cytologic features of SLDI and C19-LAP have been investigated. A search for studies that reported on C19-LAP and SLDI histopathology and cytopathology was performed on PubMed and Google Scholar, on 11 January 2023. Thirty-one reports on SLDI and C19-LAP were retrieved and included in a pooled analysis. In total, we included 54 patients with a median age of 47 years. In our research, surgical excision, CNB and/or FNAC of C19-LAP or SLDI enlarged lymph nodes have been performed in 54 cases. Of all cases, only two metastases were diagnosed and one case was diagnosed as reactive hyperplasia with atypical follicles. The remaining cases were reactive lymphadenopathy (28 cases), follicular hyperplasia (13 cases), Kikuchi-Fujimoto disease (6 cases), granulomatous lymphadenitis (2 cases), eosinophilic lymph node abscesses (1 case), Langherans cell histiocytosis (1 case), Rosai-Dorfman disease (1 case). SLDI and C19-LAP have represented a diagnostic dilemma, especially in oncologic patients. The role of different diagnostic tools for SLDI and C19-LAP has been discussed.

ACE mRNA (Additional Chimeric Element incorporated IVT mRNA) for Enhancing Protein Expression by Modulating Immunogenicity

The development of in vitro transcribed mRNA (IVT mRNA)-based therapeutics/vaccines depends on the management of IVT mRNA immunogenicity. IVT mRNA, which is used for intracellular protein translation, often triggers unwanted immune responses, interfering with protein expression and leading to reduced therapeutic efficacy. Currently, the predominant approach for mitigating immune responses involves the incorporation of costly chemically modified nucleotides like pseudouridine (Ψ) or N1-methylpseudouridine (m1Ψ) into IVT mRNA, raising concerns about expense and the potential misincorporation of amino acids into chemically modified codon sequences. Here, an Additional Chimeric Element incorporated mRNA (ACE mRNA), a novel approach incorporating two segments within a single IVT mRNA structure, is introduced. The first segment retains conventional IVT mRNA components prepared with unmodified nucleotides, while the second, comprised of RNA/DNA chimeric elements, aims to modulate immunogenicity. Notably, ACE mRNA demonstrates a noteworthy reduction in immunogenicity of unmodified IVT mRNA, concurrently demonstrating enhanced protein expression efficiency. The reduced immune responses are based on the ability of RNA/DNA chimeric elements to restrict retinoic acid-inducible gene I (RIG-I) and stimulator of interferon genes (STING)-mediated immune activation. The developed ACE mRNA shows great potential in modulating the immunogenicity of IVT mRNA without the need for chemically modified nucleotides, thereby advancing the safety and efficacy of mRNA-based therapeutics/vaccines.

An HTLV-1 envelope mRNA vaccine is immunogenic and protective in New Zealand rabbits

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus responsible for adult T-cell leukemia/lymphoma, a severe and fatal CD4+ T-cell malignancy. Additionally, HTLV-1 can lead to a chronic progressive neurodegenerative disease known as HTLV-1-associated myelopathy/tropical spastic paraparesis. Unfortunately, the prognosis for HTLV-1-related diseases is generally poor, and effective treatment options are limited. In this study, we designed and synthesized a codon optimized HTLV-1 envelope (Env) mRNA encapsulated in a lipid nanoparticle (LNP) and evaluated its efficacy as a vaccine candidate in an established rabbit model of HTLV-1 infection and persistence. Immunization regimens included a prime/boost protocol using Env mRNA-LNP or control green fluorescent protein (GFP) mRNA-LNP. After immunization, rabbits were challenged by intravenous injection with irradiated HTLV-1 producing cells. Three rabbits were partially protected and three rabbits were completely protected against HTLV-1 challenge. These rabbits were then rechallenged 15 weeks later, and two rabbits maintained sterilizing immunity. In Env mRNA-LNP immunized rabbits, proviral load and viral gene expression were significantly lower. After viral challenge in the Env mRNA-LNP vaccinated rabbits, an increase in both CD4+/IFN-γ+ and CD8+/IFN-γ+ T-cells was detected when stimulating with overlapping Env peptides. Env mRNA-LNP elicited a detectable anti-Env antibody response after prime/boost vaccination in all animals and significantly higher levels of neutralizing antibody activity. Neutralizing antibody activity was correlated with a reduction in proviral load. These findings hold promise for the development of preventive strategies and therapeutic interventions against HTLV-1 infection and its associated diseases.IMPORTANCEmRNA vaccine technology has proven to be a viable approach for effectively triggering immune responses that protect against or limit viral infections and disease. In our study, we synthesized a codon optimized human T-cell leukemia virus type 1 (HTLV-1) envelope (Env) mRNA that can be delivered in a lipid nanoparticle (LNP) vaccine approach. The HTLV-1 Env mRNA-LNP produced protective immune responses against viral challenge in a preclinical rabbit model. HTLV-1 is primarily transmitted through direct cell-to-cell contact, and the protection offered by mRNA vaccines in our rabbit model could have significant implications for optimizing the development of other viral vaccine candidates. This is particularly important in addressing the challenge of enhancing protection against infections that rely on cell-to-cell transmission.

Path towards mRNA delivery for cancer immunotherapy from bench to bedside

Messenger RNA (mRNA) has emerged as a promising therapeutic agent for the prevention and treatment of various diseases. mRNA vaccines, in particular, offer an alternative approach to conventional vaccines, boasting high potency, rapid development capabilities, cost-effectiveness, and safe administration. However, the clinical application of mRNA vaccines is hindered by the challenges of mRNA instability and inefficient in vivo delivery. In recent times, remarkable technological advancements have emerged to address these challenges, utilizing two main approaches: ex vivo transfection of dendritic cells (DCs) with mRNA and direct injection of mRNA-based therapeutics, either with or without a carrier. This review offers a comprehensive overview of major non-viral vectors employed for mRNA vaccine delivery. It showcases notable preclinical and clinical studies in the field of cancer immunotherapy and discusses important considerations for advancing these promising vaccine platforms for broader therapeutic applications. Additionally, we provide insights into future possibilities and the remaining challenges in mRNA delivery technology, emphasizing the significance of ongoing research in mRNA-based therapeutics.

Synthesis of cell penetrating peptide sterol coupler and its liposome study on S-mRNA

In order to overcome the current LNP-mRNA delivery system's weakness of poor stability and rapid degradation by nuclease, a novel chol-CGYKK molecule and then the new phospholipid liposome were designed and prepared. A solid phase approach synthesized CGYKK and connected it to cholesterol via a disulfide linker to form the desired chol-CGYKK. Four formulated samples with different proportions of excipients were prepared by freeze-drying cationic liposomes and packaged S-mRNA. The stability test shows that after six months at 4 °C, the encapsulation rate of this novel phospholipid liposome was still approximately 90%, which would significantly improve the storage and transportation requirement. Transmission electron microscopy, atomic force microscopy, and scanning electron microscopy indicated that the liposomes were spherical and uniformly dispersed. On comparing the levels of mRNA protein expression of the four formulated samples, the S protein vaccine expression of formulated sample 1 was the highest. Uptake by vector cells for formulated sample 1 showed that compared to Lipo2000, and the transfection efficiency was 66.7%. Furthermore, the safety evaluation of the CGYKK and mRNA vaccine liposomes revealed no toxic effects. The in vivo study demonstrated that this novel mRNA vaccine had an immune response. However, it was still not as good as the LNP group right now, but its excellent physicochemical properties, stability, in vitro biological activity, and in vivo efficacy against SARS-CoV-2 provided new strategies for developing the next generation of mRNA delivery system.

mRNA vaccines in disease prevention and treatment

mRNA vaccines have emerged as highly effective strategies in the prophylaxis and treatment of diseases, thanks largely although not totally to their extraordinary performance in recent years against the worldwide plague COVID-19. The huge superiority of mRNA vaccines regarding their efficacy, safety, and large-scale manufacture encourages pharmaceutical industries and biotechnology companies to expand their application to a diverse array of diseases, despite the nonnegligible problems in design, fabrication, and mode of administration. This review delves into the technical underpinnings of mRNA vaccines, covering mRNA design, synthesis, delivery, and adjuvant technologies. Moreover, this review presents a systematic retrospective analysis in a logical and well-organized manner, shedding light on representative mRNA vaccines employed in various diseases. The scope extends across infectious diseases, cancers, immunological diseases, tissue damages, and rare diseases, showcasing the versatility and potential of mRNA vaccines in diverse therapeutic areas. Furthermore, this review engages in a prospective discussion regarding the current challenge and potential direction for the advancement and utilization of mRNA vaccines. Overall, this comprehensive review serves as a valuable resource for researchers, clinicians, and industry professionals, providing a comprehensive understanding of the technical aspects, historical context, and future prospects of mRNA vaccines in the fight against various diseases.

Updated Considerations for the Immunopharmacological Aspects of the "Talented mRNA Vaccines"

Messenger RNA (mRNA) vaccines belong to a new class of medications, RNA therapeutics, including both coding and non-coding RNAs. The use of mRNA as a therapy is based on the biological role of mRNA itself, namely its translation into a functional protein. The goal of mRNA vaccines is to produce a specific antigen in cells to elicit an immune response that might be prophylactic or therapeutic. The potential of mRNA as vaccine has been envisaged for years but its efficacy has been clearly demonstrated with the approval of COVID-19 vaccines in 2021. Since then, mRNA vaccines have been in the pipeline for diseases that are still untreatable. There are many advantages of mRNA vaccines over traditional vaccines, including easy and cost-effective production, high safety, and high-level antigen expression. However, the nature of mRNA itself and some technical issues pose challenges associated with the vaccines' development and use. Here we review the immunological and pharmacological features of mRNA vaccines by discussing their pharmacokinetics, mechanisms of action, and safety, with a particular attention on the advantages and challenges related to their administration. Furthermore, we present an overview of the areas of application and the clinical trials that utilize a mRNA vaccine as a treatment.

COVID-19 post-vaccination lymphadenopathy: A review of the use of fine needle aspiration cytology

COVID-19 vaccine-associated clinical lymphadenopathy (C19-LAP) and subclinical lymphadenopathy (SLDI), which are mainly detected by 18F-FDG PET-CT, have been observed after the introduction of RNA-based vaccines during the pandemic. Lymph node (LN) fine needle aspiration cytology (FNAC) has been used to diagnose single cases or small series of SLDI and C19-LAP. In this review, clinical and LN-FNAC features of SLDI and C19-LAP are reported and compared to non-Covid (NC)-LAP. A search for studies on C19-LAP and SLDI histopathology and cytopathology was performed on PubMed and Google Scholar, on 11 January 2023. Reports on LN-FNAC of C19-LAP were retrieved. A total of 14 reports, plus one unpublished case of C19-LAP observed in our institution, diagnosed by LN-FNAC were included in a pooled analysis and compared to the corresponding histopathological reports. In total, 26 cases were included in this review, with a mean age of 50.5 years. Twenty-one lymphadenopathies assessed by LN-FNAC were diagnosed as benign, and three cases as atypical lymphoid hyperplasia; the latter were subsequently confirmed as benign (one by repetition of LN-FNAC, two by histological control). One case of mediastinal lymphadenopathy in a patient suffering from melanoma was reported as reactive granulomatous inflammation, while one unsuspected case was diagnosed as metastasis from melanoma. In all cases, the cytological diagnoses were confirmed by follow-up or excisional biopsy. The high diagnostic value of LN-FNAC in excluding malignant processes was extremely useful in this context and may be particularly valuable when CNB or histological excisions are difficult to perform, as was the case during Covid lockdowns.