Interim analyses of a first-in-human phase 1/2 mRNA trial for propionic acidaemia

The use of nanocarriers in treating Batten disease: A systematic review

The neuronal ceroid lipofuscinoses, commonly known as Batten disease, are a group of lysosomal storage disorders affecting children. There is extensive central nervous system and retinal degeneration, resulting in seizures, vision loss and a progressive cognitive and motor decline. Enzyme replacement and gene therapies are being developed, and mRNA and oligonucleotide therapies are more recently being considered. Overcoming the challenges of the blood-brain barrier and blood-ocular barrier is crucial for effectively targeting the brain and eye, whatever the therapeutic approach. Nanoparticles and extracellular vesicles are small carriers that can encapsulate a cargo and pass through these cell barriers. They have been investigated as drug carriers for other pathologies and could be a promising treatment strategy for Batten disease. Their use in gene, enzyme, or mRNA replacement therapy of all lysosomal storage disorders, including Mucopolysaccharidoses, Niemann-Pick diseases, and Fabry disease, is investigated in this systematic review. Different nanocarriers can efficiently target the lysosome and cross the barriers into the brain and eyes. This supports continued exploration of nanocarriers as potential future treatment options for Batten disease.

Systemic messenger RNA replacement therapy is effective in a novel clinically relevant model of acute intermittent porphyria developed in non-human primates

OBJECTIVE

Acute intermittent porphyria (AIP) is a rare metabolic disorder caused by haploinsufficiency of hepatic porphobilinogen deaminase (PBGD), the third enzyme of the heme biosynthesis. Individuals with AIP experience neurovisceral attacks closely associated with hepatic overproduction of potentially neurotoxic heme precursors.

DESIGN

We replicated AIP in non-human primates (NHPs) through selective knockdown of the hepatic PBGD gene and evaluated the safety and therapeutic efficacy of human PBGD (hPBGD) mRNA rescue.

RESULTS

Intrahepatic administration of a recombinant adeno-associated viral vector containing short hairpin RNA against endogenous PBGD mRNA resulted in sustained PBGD activity inhibition in liver tissue for up to 7 months postinjection. The administration of porphyrinogenic drugs to NHPs induced hepatic heme synthesis, elevated urinary porphyrin precursors and reproduced acute attack symptoms in patients with AIP, including pain, motor disturbances and increased brain GABAergic activity. The model also recapitulated functional anomalies associated with AIP, such as reduced brain perfusion and cerebral glucose uptake, disturbances in hepatic TCA cycle, one-carbon metabolism, drug biotransformation, lipidomic profile and abnormal mitochondrial respiratory chain activity. Additionally, repeated systemic administrations of hPBGD mRNA in this AIP NHP model restored hepatic PBGD levels and activity, providing successful protection against acute attacks, metabolic changes in the liver and CNS disturbances. This approach demonstrated better efficacy than the current standards of care for AIP.

CONCLUSION

This novel model significantly expands our understanding of AIP at the molecular, biochemical and clinical levels and confirms the safety and translatability of multiple systemic administration of hPBGD mRNA as a potential aetiological AIP treatment.

DARPin-induced reactivation of p53 in HPV-positive cells

Infection of cells with high-risk strains of the human papillomavirus (HPV) causes cancer in various types of epithelial tissue. HPV infections are responsible for ~4.5% of all cancers worldwide. Tumorigenesis is based on the inactivation of key cellular control mechanisms by the viral proteins E6 and E7. The HPV E6 protein interacts with the cellular E3 ligase E6AP, and this complex binds to the p53 DNA-binding domain, which results in degradation of p53. Inhibition of this interaction has the potential to reactivate p53, thus preventing oncogenic transformation. Here we describe the characterization of a designed ankyrin repeat protein that binds to the same site as the HPV E6 protein, thereby displacing the E3 ligase and stabilizing p53. Interaction with the designed ankyrin repeat protein does not affect p53 DNA binding or the crucial MDM2 negative feedback loop but reactivates a p53-dependent transcriptional program in HeLa (HPV18-positive) and SiHa (HPV16-positive) cells, suggesting a potential therapeutic use.

One-pot ligation of multiple mRNA fragments on dsDNA splint advancing regional modification and translation

Region-specific RNA modifications are crucial for advancing RNA research and therapeutics, including messenger RNA (mRNA)-based vaccines and immunotherapy. However, the predominant method, synthesizing regionally modified mRNAs with short single-stranded DNA (ssDNA) splints, encounters challenges in ligating long mRNA fragments due to the formation of RNA self-folded complex structures. To address this issue, we developed an efficient strategy using an easily obtained long double-stranded DNA (dsDNA) as a ligation splint after in situ denaturing, while parts of this dsDNA are the templates for transcribing mRNA fragments. We observed that the denatured dsDNA formed a long hybrid duplex with these mRNA fragments, overcoming their structures. Further, our novel strategy remarkably facilitated the ligation of long mRNA fragments (especially structured ones), offering ligation efficiency up to 106-fold higher than the ssDNA method. Using this one-pot strategy, we conveniently synthesized the mRNAs with N1-methylpseudouridine (m1ψ) and 5-methylcytidine (m5C) modifications in specific regions. We have found that compared with the fully modified mRNAs, the 3'UTR m1ψ modifications alone increased the translation efficiency, and the combined modifications of the m1ψ-3'UTR and m5C-5'UTR/CDS exhibited higher translation efficiency and lower immunogenicity in general. Our study presents a broadly applicable strategy for producing regionally modified mRNAs, advancing the potential of mRNA therapeutics.

Safety and immunogenicity of an optimized self-replicating RNA platform for low dose or single dose vaccine applications: a randomized, open label Phase I study in healthy volunteers

Self-replicating RNA (srRNA) technology, in comparison to mRNA vaccines, has shown dose-sparing by approximately 10-fold and more durable immune responses. However, no improvements are observed in the adverse events profile. Here, we develop an srRNA vaccine platform with optimized non-coding regions and demonstrate immunogenicity and safety in preclinical and clinical development. Optimized srRNA vaccines generate protective immunity (according to the WHO defined thresholds) at doses up to 1,000,000-fold lower than mRNA in female mouse models of influenza and rabies. Clinically, safety and immunogenicity of RBI-4000, an srRNA vector encoding the rabies glycoprotein, was evaluated in a Phase I study (NCT06048770). RBI-4000 was able to elicit de novo protective immunity in the majority of healthy participants when administered at a dose of 0.1, 1, or 10 microgram (71%, 94%, 100%, respectively) in a prime-boost schedule. Similarly, we observe immunity above the WHO benchmark of protection following a single administration in most participants at both 1 and 10 microgram doses. There are no serious adverse events reported across all cohorts. These data establish the high therapeutic index of optimized srRNA vectors, demonstrating feasibility of both low dose and single dose approaches for vaccine applications.

Therapeutic applications of cell engineering using mRNA technology

Engineering and reprogramming cells has significant therapeutic potential to treat a wide range of diseases, by replacing missing or defective proteins, to provide transcription factors (TFs) to reprogram cell phenotypes, or to provide enzymes such as RNA-guided Cas9 derivatives for CRISPR-based cell engineering. While viral vector-mediated gene transfer has played an important role in this field, the use of mRNA avoids safety concerns associated with the integration of DNA into the host cell genome, making mRNA particularly attractive for in vivo applications. Widespread application of mRNA for cell engineering is limited by its instability in the biological environment and challenges involved in the delivery of mRNA to its target site. In this review, we examine challenges that must be overcome to develop effective therapeutics.

Role of carglumic acid in the long-term management of propionic and methylmalonic acidurias

Propionic aciduria (PA) and methylmalonic aciduria (MMA) are rare inherited disorders caused by defects in the propionate metabolic pathway. PA due to propionyl coenzyme A carboxylase deficiency results in accumulation of propionic acid, while in MMA, deficiency in methylmalonyl coenzyme A mutase leads to accumulation of methylmalonic acid. Hyperammonemia is related to a secondary deficiency of N-acetylglutamate (NAG), the activator of carbamoyl phosphate synthetase 1, which is an irreversible rate-limiting enzyme in the urea cycle. Carglumic acid (CGA) is a synthetic structural analog of human NAG and is approved for the treatment of patients with hyperammonemia due to PA or MMA. CGA is well tolerated and its use in normalizing ammonia levels during acute hyperammonemic episodes in patients with PA and MMA is well established. This expert opinion analyzed clinical evidence for CGA and discussed its place, along with other management strategies, in the long-term management of PA or MMA. A literature search of PubMed was undertaken to identify publications related to the chronic use of CGA, transplantation, dietary management, ammonia scavengers, and gene therapy for treatment of patients with PA or MMA. The authors selected the most relevant studies for inclusion. Four clinical studies, one single center case series, and three case reports show that CGA is safe and effective in the chronic treatment of PA and MMA. In particular, the addition of CGA is associated with a reduction in hyperammonemic decompensation episodes and admission to hospital, compared with conventional dietary treatment alone. Current treatment guidelines and recommendations include the use of CGA mainly in acute decompensation, however, lag in considering the benefits of long-term CGA treatment on clinical and biochemical outcomes in patients with PA or MMA. CGA is safe and effective in the chronic treatment of PA and MMA and may help to resolve some of the issues associated with other strategies used to treat these disorders. Thus, CGA appears to have potential for the chronic management of patients with PA and MMA and should be recommended for inclusion in the chronic treatment of these disorders.

DARPins as a novel tool to detect and degrade p73

The concept of Targeted Protein Degradation (TPD) has been introduced as an attractive alternative to the development of classical inhibitors. TPD can extend the range of proteins that can be pharmacologically targeted beyond the classical targets for small molecule inhibitors, as a binding pocket is required but its occupancy does not need to lead to inhibition. The method is based on either small molecules that simultaneously bind to a protein of interest and to a cellular E3 ligase and bring them in close proximity (molecular glue) or a bi-functional molecule synthesized from the chemical linkage of a target protein-specific small molecule and one that binds to an E3 ligase (Proteolysis Targeting Chimeras (PROTAC)). The further extension of this approach to bioPROTACs, in which a small protein-based binding module is fused directly to an E3 ligase or an E3 ligase adaptor protein, makes virtually all proteins amenable to targeted degradation, as this method eliminates the requirement for binding pockets for small molecules. Designed Ankyrin Repeat Proteins (DARPins) represent a very attractive class of small protein-based binding modules that can be used for the development of bioPTOTACS. Here we describe the characterization of two DARPins generated against the oligomerization domain and the SAM domain of the transcription factor p73, a member of the p53 protein family. The DARPins can be used for (isoform-)selective pulldown experiments both in cell culture as well as primary tissue lysates. We also demonstrate that they can be used for staining in cell culture experiments. Fusing them to the speckle type POZ protein (SPOP), an adaptor protein for cullin-3 E3 ligase complexes, yields highly selective and effective degraders. We demonstrate that selective degradation of the ΔNp73α isoform reactivates p53.

Codon optimality modulates cellular stress and innate immune responses triggered by exogenous RNAs

The COVID-19 mRNA vaccines demonstrated the power of mRNA medicines. Despite advancements in sequence design, evidence regarding the preferential use of synonymous codons on cellular stress and innate immune responses is lacking. To this end, we developed a proprietary codon optimality matrix to re-engineer the coding sequences of three luciferase reporters. We demonstrate that optimal mRNAs elicited dramatic increases in luciferase activities compared to non-optimal sequences. Notably, transfecting an optimal RNA affects the translation of other RNAs in the cell including control transcripts in dual luciferase assays. This held true in multiple cell lines and for an unrelated reporter. Further, non-optimal mRNAs preferentially activated innate immune pathways and the phosphorylation of the translation initiation factor eIF2α, a central event of the integrated stress response. Using nucleoside-modified or circular RNAs partially or fully abrogated these responses. Finally, we show that circularizing RNAs enhances both RNA lifespan and durability of protein expression. Our results show that RNA sequence, composition, and structure all govern RNA translatability. However, we also show that RNA sequences with poor codon optimality are immunogenic and induce cellular stress. Hence, RNA sequence engineering, chemical, and topological modifications must all be combined to elicit favorable therapeutic outcomes.

Progress and prospects of mRNA-based drugs in pre-clinical and clinical applications

In the last decade, messenger ribonucleic acid (mRNA)-based drugs have gained great interest in both immunotherapy and non-immunogenic applications. This surge in interest can be largely attributed to the demonstration of distinct advantages offered by various mRNA molecules, alongside the rapid advancements in nucleic acid delivery systems. It is noteworthy that the immunogenicity of mRNA drugs presents a double-edged sword. In the context of immunotherapy, extra supplementation of adjuvant is generally required for induction of robust immune responses. Conversely, in non-immunotherapeutic scenarios, immune activation is unwanted considering the host tolerability and high expression demand for mRNA-encoded functional proteins. Herein, mainly focused on the linear non-replicating mRNA, we overview the preclinical and clinical progress and prospects of mRNA medicines encompassing vaccines and other therapeutics. We also highlight the importance of focusing on the host-specific variations, including age, gender, pathological condition, and concurrent medication of individual patient, for maximized efficacy and safety upon mRNA administration. Furthermore, we deliberate on the potential challenges that mRNA drugs may encounter in the realm of disease treatment, the current endeavors of improvement, as well as the application prospects for future advancements. Overall, this review aims to present a comprehensive understanding of mRNA-based therapies while illuminating the prospective development and clinical application of mRNA drugs.

Extracellular vesicles versus lipid nanoparticles for the delivery of nucleic acids

Extracellular vesicles (EVs) are increasingly investigated for delivering nucleic acid (NA) therapeutics, leveraging their natural role in transporting NA and protein-based cargo in cell-to-cell signaling. Their synthetic counterparts, lipid nanoparticles (LNPs), have been developed over the past decades as NA carriers, culminating in the approval of several marketed formulations such as patisiran/Onpattro® and the mRNA-1273/BNT162 COVID-19 vaccines. The success of LNPs has sparked efforts to develop innovative technologies to target extrahepatic organs, and to deliver novel therapeutic modalities, such as tools for in vivo gene editing. Fueled by the recent advancements in both fields, this review aims to provide a comprehensive overview of the basic characteristics of EV and LNP-based NA delivery systems, from EV biogenesis to structural properties of LNPs. It addresses the primary challenges encountered in utilizing these nanocarriers from a drug formulation and delivery perspective. Additionally, biodistribution profiles, in vitro and in vivo transfection outcomes, as well as their status in clinical trials are compared. Overall, this review provides insights into promising research avenues and potential dead ends for EV and LNP-based NA delivery systems.

Liver gene transfer for metabolite detoxification in inherited metabolic diseases

Inherited metabolic disorders (IMDs) are a growing group of genetic diseases caused by defects in enzymes that mediate cellular metabolism, often resulting in the accumulation of toxic substrates. The liver is a highly metabolically active organ that hosts several thousands of chemical reactions. As such, it is an organ frequently affected in IMDs. In this article, we review current approaches for liver-directed gene-based therapy aimed at metabolite detoxification in a variety of IMDs. Moreover, we discuss current unresolved challenges in gene-based therapies for IMDs.

Development of mRNA Lipid Nanoparticles: Targeting and Therapeutic Aspects

Lipid nanoparticles (LNPs) have emerged as leading non-viral carriers for messenger RNA (mRNA) delivery in clinical applications. Overcoming challenges in safe and effective mRNA delivery to target tissues and cells, along with controlling release from the delivery vehicle, remains pivotal in mRNA-based therapies. This review elucidates the structure of LNPs, the mechanism for mRNA delivery, and the targeted delivery of LNPs to various cells and tissues, including leukocytes, T-cells, dendritic cells, Kupffer cells, hepatic endothelial cells, and hepatic and extrahepatic tissues. Here, we discuss the applications of mRNA-LNP vaccines for the prevention of infectious diseases and for the treatment of cancer and various genetic diseases. Although challenges remain in terms of delivery efficiency, specific tissue targeting, toxicity, and storage stability, mRNA-LNP technology holds extensive potential for the treatment of diseases.

Insights into the formulation of lipid nanoparticles for the optimization of mRNA therapeutics

mRNA-based therapeutics increasingly demonstrate significant potential in treating various diseases, including infectious diseases, cancers, and genetic disorders. Effective delivery systems are crucial for advancing mRNA therapeutics. Lipid nanoparticles (LNPs) serve as an excellent carrier, widely validated for their safety and tolerability in commercially available mRNA vaccines. Standard LNPs typically consist of four components: ionizable lipids (ILs), helper lipids, cholesterol, and polyethylene glycol-lipids (PEG-lipids), with the structural design of ILs gradually becoming a focal point of research interest. The chemical structures and formulations of the other components also significantly affect the delivery efficiency, targeting specificity, and stability of LNPs. The complex formulations of LNPs may hinder the clinical transformation of mRNA therapeutics and have raised widespread concerns about their safety. This review aims to summarize the progress of LNPs-based mRNA therapeutics in clinical trials, focusing on adverse effects that occurred during these trials. It also discusses representative innovations in LNP components, highlighting challenges and potential ways in this research field. We firmly believe this review will promote further improvements and designs of LNP compositions to optimize mRNA therapeutics. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Lipid-Based Structures.

The 60-year evolution of lipid nanoparticles for nucleic acid delivery

Delivery of genetic information to the interior of target cells in vivo has been a major challenge facing gene therapies. This barrier is now being overcome, owing in part to dramatic advances made by lipid-based systems that have led to lipid nanoparticles (LNPs) that enable delivery of nucleic acid-based vaccines and therapeutics. Examples include the clinically approved COVID-19 LNP mRNA vaccines and Onpattro (patisiran), an LNP small interfering RNA therapeutic to treat transthyretin-induced amyloidosis (hATTR). In addition, a host of promising LNP-enabled vaccines and gene therapies are in clinical development. Here, we trace this success to two streams of research conducted over the past 60 years: the discovery of the transfection properties of lipoplexes composed of positively charged cationic lipids complexed with nucleic acid cargos and the development of lipid nanoparticles using ionizable cationic lipids. The fundamental insights gained from these two streams of research offer potential delivery solutions for most forms of gene therapies.

Recent Advancements in mRNA Vaccines: From Target Selection to Delivery Systems

mRNA vaccines are leading a medical revolution. mRNA technologies utilize the host's own cells as bio-factories to produce proteins that serve as antigens. This revolutionary approach circumvents the complicated processes involved in traditional vaccine production and empowers vaccines with the ability to respond to emerging or mutated infectious diseases rapidly. Additionally, the robust cellular immune response elicited by mRNA vaccines has shown significant promise in cancer treatment. However, the inherent instability of mRNA and the complexity of tumor immunity have limited its broader application. Although the emergence of pseudouridine and ionizable cationic lipid nanoparticles (LNPs) made the clinical application of mRNA possible, there remains substantial potential for further improvement of the immunogenicity of delivered antigens and preventive or therapeutic effects of mRNA technology. Here, we review the latest advancements in mRNA vaccines, including but not limited to target selection and delivery systems. This review offers a multifaceted perspective on this rapidly evolving field.

Emerging mRNA Technology for Liver Disease Therapy

Liver diseases have consistently posed substantial challenges to global health. It is crucial to find innovative methods to effectively prevent and treat these diseases. In recent times, there has been an increasing interest in the use of mRNA formulations that accumulate in liver tissue for the treatment of hepatic diseases. In this review, we start by providing a detailed introduction to the mRNA technology. Afterward, we highlight types of liver diseases, discussing their causes, risks, and common therapeutic strategies. Additionally, we summarize the latest advancements in mRNA technology for the treatment of liver diseases. This includes systems based on hepatocyte growth factor, hepatitis B virus antibody, left-right determination factor 1, human hepatocyte nuclear factor α, interleukin-12, methylmalonyl-coenzyme A mutase, etc. Lastly, we provide an outlook on the potential of mRNA technology for the treatment of liver diseases, while also highlighting the various technical challenges that need to be addressed. Despite these difficulties, mRNA-based therapeutic strategies may change traditional treatment methods, bringing hope to patients with liver diseases.

[« ReNAissance » of biotherapies with RNA]

Many diseases originate from either the absence or defective expression of a given protein. For some of them, the lacking protein is secreted or can be taken up by cells when delivered exogenously. In such cases, therapies initially involved administering the physiological protein extracted from human tissues. Subsequently, genetic engineering enabled the production of proteins through cell fermentation after introducing the corresponding gene. For many other pathologies, the deficient protein cannot be delivered exogenously. Thus, an endogenous production of the therapeutic protein by the cells themselves is necessary. Messenger RNA (mRNA) technology, like its predecessor DNA, aims to supplement the genetic information needed to produce the therapeutic protein within the cells. However, unlike DNA-based therapies, mRNA transfer allows for transient expression of the protein of interest, which offers an advantage in numerous pathologies. Nonetheless, mastering the quantity, quality, and spatio-temporal regulation of protein production encoded by therapeutic mRNA remains a significant challenge for the development of this approach.

Exploration of Gene Therapy for Alport Syndrome

Alport syndrome is a hereditary disease caused by mutations in the genes encoding the alpha 3, alpha 4, and alpha 5 chains of type IV collagen. It is characterized by hematuria, proteinuria, progressive renal dysfunction, hearing loss, and ocular abnormalities. The main network of type IV collagen in the glomerular basement membrane is composed of α3α4α5 heterotrimer. Mutations in these genes can lead to the replacement of this network by an immature network composed of the α1α1α2 heterotrimer. Unfortunately, this immature network is unable to provide normal physical support, resulting in hematuria, proteinuria, and progressive renal dysfunction. Current treatment options for Alport syndrome include angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, which aim to alleviate glomerular filtration pressure, reduce renal injury, and delay the progression of renal dysfunction. However, the effectiveness of these treatments is limited, highlighting the need for novel therapeutic strategies and medications to improve patient outcomes. Gene therapy, which involves the use of genetic material to prevent or treat diseases, holds promise for the treatment of Alport syndrome. This approach may involve the insertion or deletion of whole genes or gene fragments to restore or disrupt gene function or the editing of endogenous genes to correct genetic mutations and restore functional protein synthesis. Recombinant adeno-associated virus (rAAV) vectors have shown significant progress in kidney gene therapy, with several gene therapy drugs based on these vectors reaching clinical application. Despite the challenges posed by the structural characteristics of the kidney, the development of kidney gene therapy using rAAV vectors is making continuous progress. This article provides a review of the current achievements in gene therapy for Alport syndrome and discusses future research directions in this field.

The Platform Technology Approach to mRNA Product Development and Regulation

mRNA-lipid nanoparticle (LNP) medicinal products can be considered a platform technology because the development process is similar for different diseases and conditions, with similar noncoding mRNA sequences and lipid nanoparticles and essentially unchanged manufacturing and analytical methods often utilised for different products. It is critical not to lose the momentum built using the platform approach during the development, regulatory approval and rollout of vaccines for SARS-CoV-2 and its variants. This review proposes a set of modifications to existing regulatory requirements for mRNA products, based on a platform perspective for quality, manufacturing, preclinical, and clinical data. For the first time, we address development and potential regulatory requirements when the mRNA sequences and LNP composition vary in different products as well. In addition, we propose considerations for self-amplifying mRNA, individualised oncology mRNA products, and mRNA therapeutics. Providing a predictable development pathway for academic and commercial groups so that they can know in detail what product characterisation and data are required to develop a dossier for regulatory submission has many potential benefits. These include: reduced development and regulatory costs; faster consumer/patient access and more agile development of products in the face of pandemics; and for rare diseases where alternatives may not exist or to increase survival and the quality of life in cancer patients. Therefore, achieving consensus around platform approaches is both urgent and important. This approach with mRNA can be a template for similar platform frameworks for other therapeutics and vaccines to enable more efficient development and regulatory review.