INTRODUCTION:

The pharmaceutical sector has much to celebrate. Significant treatment advances over the past decade, therapeutic breakthroughs—such as immunotherapy, mRNA vaccines, and gene therapy— have given across the world fresh hope to patients around the world.The quick creation of COVID-19 vaccines, achieved in record time, played a crucial role in fight against a historic worldwide pandemic.

This review will examine RNA therapy, an innovative approach that uses RNA-based compounds to modify biological pathways and treat various diseases.

Target molecules' RNA sequences are used in RNA treatment to modify their expression or activity¹. Once the appropriate nucleic acid chemistry and delivery systems are established, RNA-based medications can be developed relatively quickly for new targets. This remarkable capability has positioned messenger RNA (mRNA)—a key subtype of RNA therapy—as a powerful and effective tool in vaccine development especially in the fight against COVID-19. However, these current developments become feasible only through more than three decades of research and development in the field². Despite the remarkable success of mRNA vaccines, interest in RNA-based treatments has continued to grow. Recent studies have been discovered a wide range of RNA molecules, including noncoding RNAs, which play essential roles in cellular processes. These discoveries have positioned RNA as a promising target for treating a number of human illnesses³. RNAs and small interfering RNAs (siRNAs) have already been developed and are in clinical use, following years of intensive research and optimization. Current initiatives are focused on advancing messenger RNA (mRNA)-based therapies and RNA aptamers treatments.In addition to these developments, a number of delivery mechanisms have been developed to enhance the intracellular transport and stability of RNA therapeutics⁴.

History of RNA therapy:

RNA therapy, once a theoretical concept, has evolved into a powerful clinical tool through decades of research, scientific innovation, and technological advancement.

1. Discovery Phase (1950s–1970s):

· 1956: RNA was identified as a crucial as a key messenger molecule. Sydney Brenner, François Jacob, and Matthew Meselson proposed the concept of messenger RNA (mRNA) that carries genetic information from DNA to ribosomes.

· 1977: The discovery of RNA splicing by Phillip Sharp and Richard Roberts showed that RNA can be processed which opened the possibility of modulating RNA for therapeutic purposes ⁵.

2. Early Experiments and Conceptualization (1980s–1990s)

· Antisense technology was developed as a way to selectively inhibit gene expression by creating short RNA or DNA sequences that bind to specific mRNA targets.

· In 1998, Fire and Mello demonstrated RNA interference (RNAi) in C. elegans, revealing that small double-stranded RNAs could silence gene expression with great specificity. This discovery earned them the Nobel Prize in 2006⁶.

3. Clinical Translation and First Approvals (2000s–2010s)

· 2004: The first FDA-approved RNA-based medication was Pegaptanib (Macugen), an RNA aptamer targeting VEGF165 for age-related macular degeneration.

· 2006–2010: Significant investment in siRNA and antisense oligonucleotides (ASOs) led to multiple candidates entering clinical trials.

· 2016: Nusinersen (Spinraza) was the first ASO approved for treating spinal muscular atrophy (SMA).

· 2018: Patisiran (Onpattro) ) was the first FDA-approved siRNA drug for hereditary transthyretin amyloidosis (hATTR) using lipid nanoparticle delivery⁷.

4. Breakthrough with mRNA Vaccines (2020–Present):

2020: Two COVID-19 vaccines based on mRNA and lipid nanoparticle (LNP) delivery systems, Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273), were given emergency use authorization. These vaccines demonstrated mRNA as a revolutionary therapeutic platform through their quick development, excellent efficacy, and scalability⁸.

5. Expansion into New Therapies (2020s–Future):

· Ongoing clinical trials are investigated RNA treatments for cancer, neurodegenerative diseases, uncommon genetic disorders, and infectious diseases.

· Emerging technologies include self-amplifying RNA, circular RNA, and CRISPR-based RNA therapies.

· Personalized "n-of-1" RNA medicines and next-gen delivery platforms (e.g., exosomes, GalNAc conjugates) are in development⁹.

Figure 1-History of RNA Therapeutics

Advantage of RNA therapy:

RNA-based medications offer numerous advantageous properties like high specificity in targeting genes, rapid and adaptable drug design, and the ability to address diseases that were previously considered untreatable ³.

Targeting undruggable Target:

One of the key advantages of RNA-based therapeutics is their ability to target nearly any genetic element within a cell, including those considered "undruggable" by conventional approaches such as small molecules or antibodies. Traditional drug technologies often struggle to effectively engage noncoding RNAs, which lack distinct structural features. In contrast, RNA-based agents—such as antisense RNAs and small interfering RNAs (siRNAs)—bind to their targets through precise, sequence-specific interactions. This makes them particularly well-suited for targeting noncoding RNAs, which are more abundant in the human genome than protein-coding genes³.

Fast Production:

Unlike traditional small molecule or antibody-based drugs, which often require years of development, RNA-based therapies can be designed and synthesized rapidly once the RNA's chemical structure and delivery method are established. This flexibility allows for quick adaptation to different diseases by simply modifying the nucleotide sequence. For example, if an siRNA-based drug is developed to target gene overexpression in a specific organ, other diseases in the same organ may potentially be treated by altering only the siRNA sequence³.

Long Term Effect:

While natural RNAs are typically degraded rapidly by cellular nucleases, their stability can be significantly enhanced through chemical modifications. These modifications help protect RNA molecules from enzymatic breakdown. Furthermore, when RNA is delivered using protective carriers—such as liposomes—it is shielded from nuclease activity following systemic administration. This encapsulation extends the RNA's lifespan in the body, enabling longer therapeutic effects ³.

Useful for Rare Disease:

RNA-based therapeutics, particularly exogenous messenger RNA, represent a promising new class of drugs with broad applications, including the treatment of rare monogenic disorders. Recent advancements in mRNA technology—such as chemical modifications to enhance mRNA stability and improved delivery systems—have significantly increased the therapeutic potential of mRNA. These innovations have enabled mRNA to function effectively in restoring or replacing missing or defective proteins. Preclinical proof-of-concept studies have already demonstrated the potential of mRNA therapy in treating rare genetic conditions such as Fabry disease, acute intermittent porphyria, and methylmalonic academia¹⁰.

No risk of genotoxicity: One of the key safety advantages of RNA-based therapy is its minimal risk of genotoxicity. In contrast to DNA-based therapeutics, which often rely on viral vectors for delivery and may integrate into the host genome—potentially causing insertional mutations—RNA therapies function in the cytoplasm without entering the nucleus. As a result, RNA therapy offers a safer alternative by avoiding the genotoxic risks associated with genomic integration³.

Type of RNA Therapy:

Based on their structural traits and modes of action, RNA-based medications may be divided into four distinct types based on their structural characteristics and mechanisms of action.

1. Si-RNA Therapy:

Small interfering RNAs (siRNAs) mediate gene silencing through a well-characterized biological mechanism that has been safely applied in humans. These ~13 kDa double-stranded RNA molecules guide the RNA-induced silencing complex (RISC) to complementary messenger RNA (mRNA) targets via Watson-Crick base pairing, leading to the inhibition of protein translation.

Within RISC, the catalytic component Argonaute 2 (Ago2)—a key member of the Argonaute protein family—cleaves the target mRNA, thereby preventing its translation. siRNAs are capable of downregulating protein-coding genes with high specificity and have led to the development of RNA-based drugs that have received regulatory approval from the FDA and EMA¹¹.

2. Antisense Oligonucleotide:

Antisense oligonucleotides (ASOs) exert their therapeutic effects through three primary mechanisms. First, like siRNAs, ASOs bind to target mRNAs through Watson-Crick base pairing. However, unlike siRNAs, which recruit the RNA-induced silencing complex (RISC), ASO–RNA heteroduplexes engage RNase H1, leading to cleavage of the RNA strand. These RNase H1-dependent ASOs, commonly referred to as "gapmers," effectively reduce gene expression through this enzymatic degradation pathway¹¹. Second, ASOs can modulate RNA splicing by binding to pre-mRNAs and altering splice site selection. This mechanism enables the production of functional proteins in conditions where splicing defects contribute to disease. Notably, ASOs have been employed to enhance protein expression in diseases like Duchenne muscular dystrophy and spinal muscular atrophy, in contrast to siRNAs, which primarily suppress gene expression.

The third mechanism involves blocking the translation of target mRNAs by binding directly to the translation start codon, thereby preventing ribosome assembly and subsequent protein synthesis¹¹.

3. mRNA:

Messenger RNAs (mRNAs) represent a vital class of RNA therapeutics capable of encoding proteins with therapeutic functions. Unlike smaller RNA molecules, mRNAs are relatively large and must be synthesized in vitro, as current solid-phase synthesis methods do not support site-specific chemical modifications for molecules of this size. One of the primary uses of mRNA therapeutics is in protein replacement therapy, where the mRNA provides instructions for cells to produce deficient or dysfunctional proteins. Additionally, mRNA can be engineered to reduce protein levels using CRISPR-Cas9-mediated gene editing or to correct mutations at the DNA level through base editing techniques¹².

4. Aptamers:

Aptamers are nucleic acid constructs designed to bind specific proteins and modulate their activity. To date, only one RNA-based aptamer drug, pegaptanib, has received approval from the US FDA. Pegaptanib is a 28-nucleotide RNA aptamer with two polyethylene glycol (PEG) groups attached at its ends. Its therapeutic effect arises from binding to the 165 isoform of vascular endothelial growth factor (VEGF), thereby preventing the primary downstream consequence of VEGF signaling—suppression of cell proliferation. This mechanism makes pegaptanib effective for treating wet-type (neovascular) age-related macular degeneration (AMD). Nevertheless, additional aptamer-based therapeutics are expected to become available in the future, with several RNA aptamers currently under development¹³.

Challenges in RNA Therapeutics:

Delivery Systems: One of the most significant hurdles in RNA therapeutics is achieving efficient and targeted delivery of RNA molecules into the desired cells. RNA molecules are inherently unstable and susceptible to degradation by nucleases present in biological fluids. Additionally, their large size and negative charge prevent easy passage across the hydrophobic cell membrane. To overcome these challenges, various delivery systems have been developed, including lipid nanoparticles, viral vectors, polymer-based carriers, and conjugation to targeting ligands such as aptamers or antibodies. Lipid nanoparticles, for example, have proven successful in delivering mRNA vaccines for COVID-19, providing protection from enzymatic degradation and facilitating cellular uptake via endocytosis. However, ensuring tissue specificity and efficient endosomal escape remains an ongoing challenge that limits the effectiveness and safety profile of RNA therapies^14,15.

Stability and Metabolic Degradation:

RNA molecules are highly prone to rapid degradation by nucleases in the bloodstream and within cells, which significantly reduces their therapeutic window. To address this, chemical modifications have been widely employed to enhance stability without compromising RNA function. Common modifications include 2’-O-CH₃and 2’-fluoro substitutions on the pentose sugar, phosphorothioate backbone linkages, and conjugation with polyethylene glycol (PEGylation). PEGylation not only prolongs the circulation time by reducing renal clearance but also diminishes immunogenicity and improves solubility. Such strategies increase the half-life of RNA drugs and increse their bioavailability, so improve therapeutic activity^16,13.

Immune Response and Toxicity:

Unintended activation of the innate immune system is a critical challenge in RNA therapeutics. Exogenous RNA molecules can be recognized by type of identification receptors (PRRs) such as Toll-like receptors (TLRs), RIG-I-like receptors, and others, triggering inflammatory responses. This immune activation can lead to adverse event covering from mild flu-like symptoms to serious cytokine storms. To mitigate these events, chemical modifications like pseudouridine and 5-methylcytidine substitutions are fused to reduce immunogenicity. Furthermore, careful design of delivery vehicles to avoid immune cell activation and off-target interactions is essential. Off-target effects also pose toxicity risks, as unintended gene silencing or protein binding may disrupt normal cellular functions. Hence, thorough preclinical evaluation of immune responses and toxicity profiles is crucial before clinical application^17,18.

Clinical Applications and Approved RNA Therapeutics:

Approved Drugs:

RNA therapeutics have transitioned from experimental tools to clinically approved drugs, offering new treatments for genetic, degenerative, and infectious diseases. Several RNA-based drugs have received regulatory approval and are in clinical use:

· Pegaptanib (Macugen): Pegaptanib is an RNA aptamer that selectively binds the VEGF165 isoform, inhibiting angiogenesis in wet age-related macular degeneration (AMD). Despite its initial promise, its clinical use has declined due to the emergence of more effective antibody-based therapies¹³.

· Nusinersen (Spinraza): An antisense oligonucleotide (ASO) that modulates the splicing of SMN2 pre-mRNA, increasing the production of functional SMN protein in patients with spinal muscular atrophy (SMA). Approved by the FDA in 2016, it is administered intrathecally due to its target in the CNS.

· Patisiran (Onpattro): A small interfering RNA (siRNA) therapeutic targeting transthyretin (TTR) mRNA to treat hereditary transthyretin-mediated amyloidosis (hATTR). Patisiran uses lipid nanoparticles for delivery and was approved in 2018, marking a milestone as the first FDA-approved siRNA drug⁷.

· mRNA Vaccines for COVID-19: The Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273) vaccines are established on lipid nanoparticle-encapsulated mRNA encoding the SARS-CoV-2 spike protein. These vaccines demonstrated high efficacy and rapid development timelines, underscoring the potential of mRNA therapeutics for. Their success has accelerated investment in mRNA platforms for cancer, rare diseases, and other pathogens ^9.

Emerging Therapies in Trials:

The clinical pipeline of RNA-based therapies is rapidly expanding and is currently in various stages of clinical trials, targeting a wide range of diseases:

· Cancer: RNA drugs are being designed to target oncogenes, enhance tumor immunogenicity, or deliver cancer vaccines. mRNA cancer vaccines (e.g., BioNTech’s BNT111 for melanoma) and siRNAs targeting tumor-specific genes (e.g., STAT3 or KRAS) are in development.

· Genetic Disorders: RNA therapies are being trialed for diseases such as cystic fibrosis (e.g., mRNA for CFTR protein replacement), Duchenne muscular dystrophy (e.g., exon-skipping ASOs), and Huntington’s disease (e.g., ASOs targeting mutant HTT mRNA) ⁹.

· Neurological Conditions: Beyond SMA, RNA therapies are advancing for Alzheimer’s disease, ALS, and epilepsy. For example, ASOs are under investigation to reduce tau protein expression or modulate neuronal gene splicing.

· Viral Infections: mRNA platforms are being applied to develop vaccines against influenza, Zika, RSV, and HIV. These vaccines offer rapid scalability and adaptability in response to viral mutations.

· Rare and Orphan Diseases: RNA therapeutics are particularly suited for rare diseases due to the ability to rapidly design sequences based on genetic data. Several personalized ASOs have been developed under “n-of-1” approaches.

Future Perspectives:

RNA therapeutics is composed to transform medicine in the coming decades, not only by expanding the range of treatable conditions but also by enabling personalized and precision approaches. Continued innovation in delivery systems, target choice and curative design will describe the next generation of RNA-based healthcare.

Personalized RNA Medicine:

The integration of genomic sequencing into clinical practice has opened doors to personalized RNA-based therapies. By analyzing a patient’s genetic mutations or gene expression profiles, clinicians can design RNA molecules—such as antisense oligonucleotides (ASOs) or small interfering RNAs (siRNAs)—tailored to correct or silence specific defective genes. Notably, n-of-1 therapies (custom ASOs designed for a single patient) have already been developed in cases of ultra-rare diseases. Furthermore, the speed at which RNA therapeutics can be designed and synthesized makes them ideal for individualized approaches. As genomic amplify and sequencing becomes cheaper, personalized RNA medicine will likely develop into a common clinical tool¹⁹.

Innovations in Delivery Technologies:

Efficient and safe delivery of RNA molecules remains a primary challenge, but innovative delivery platforms are making major strides:

· Lipid Nanoparticles (LNPs): Already used successfully in mRNA vaccines, LNPs are being optimized for organ-specific targeting and improved endosomal escape.

· Exosomes: Naturally occurring extracellular vesicles that can carry RNA molecules between cells; they are being engineered for RNA drug delivery with reduced immunogenicity.

· Conjugates: Ligand-based conjugation (e.g., GalNAc conjugates for liver targeting) enables receptor-specific RNA delivery, improving precision and reducing off-target effects.These systems are essential for expanding RNA therapeutics beyond the liver, brain, and muscle—tissues with historically limited accessibility²⁰.

Expanding Therapeutic Targets:

RNA therapeutics offer the unique ability to target a wide variety of molecules, including those previously deemed "undruggable" by traditional small molecules or monoclonal antibodies. These include:

· Non-coding RNAs (e.g., lncRNAs, miRNAs): Implicated in cancer, metabolic disorders, and neurodegeneration.

· Mutant Alleles: RNA therapies can be designed to selectively silence or correct disease-causing gene variants without affecting normal alleles.

· Transcription Factors and Scaffold Proteins: Traditionally inaccessible by conventional therapies but modifiable at the RNA level.

This expansion greatly increases the number of diseases that could be treated using RNA-based interventions⁹.

Combination Therapies: Linking RNA Therapeutics: with alternative treatment methods is a promising strategy for improving therapeutic outcomes. This includes:

· RNA+Chemotherapy: RNA drugs can sensitize tumors to chemotherapeutic agents by silencing drug resistance genes.

· RNA+Immunotherapy: mRNA vaccines or siRNAs can enhance immune understanding of tumors, developing responses to immune checkpoint inhibitors.

· RNA+Gene Therapy: ASOs and CRISPR-based editing tools can be combined for additive or synergistic effects in correcting genetic mutations.

These combination strategies allow for multi-pronged interventions that can simultaneously address different aspects of complex diseases, particularly in cancer and rare genetic conditions ^{21, 22}. Exosomes, nanosized extracellular vesicles secreted by cancer cells, carry a cargo of miRNAs that reflect the molecular alterations associated with tumor progression and metastasis²³.

CONCLUSION:

The application of various RNAs to specifically function on up until now "undruggable" proteins, transcripts, and genes is encouraged by the growing understanding of RNA roles and their crucial functions in ailments, possibly broadening the therapeutic targets. While a few RNA-based medicines are still being studied or in preclinical trials, others have already received clinical approval. RNA-based therapeutics have plastered significant barrier in the improvement of intracellular trafficking and metabolic stability, but a variety of strategies have been investigated Future advances in RNA therapeutics will be driven by developments in genomics, nanotechnology, and biological understanding of disease. With ongoing research, the field is rapidly evolving toward more precise, personalized, and effective therapeutic solutions.

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Received on 12.08.2025 Revised on 03.10.2025

Accepted on 15.11.2025 Published on 12.02.2026

Available online from February 14, 2026

Res.J. Pharmacology and Pharmacodynamics.2026;18(1):29-34.

DOI: 10.52711/2321-5836.2026.00004

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