RNA Therapeutics in Viral Infections and Cancer: Mechanisms, Challenges, and Prospects: A Review

Background: RNA therapeutics represent a rapidly advancing field with significant potential for treating viral infections and cancer. This review examines the current landscape of RNA-based strategies, including siRNA, miRNA mimics, and antisense oligonucleotides. For viral infections, the focus is on hepatitis B (HBV) and C (HCV), HIV, and SARS-CoV-2. Approaches include targeting viral transcripts directly (e.g., siRNAs against HBV surface antigen) or host factors critical for viral replication (e.g., anti-miR-122 miravirsen for HCV). The successful development of mRNA vaccines for COVID-19 is highlighted as a major breakthrough, demonstrating the feasibility of rapid RNA vaccine deployment. The manuscript reviews several RNA therapeutics in oncology that have reached clinical trials. These include TargomiR (a miR-16 mimic for mesothelioma), cobomarsen (an anti-miR-155 for lymphomas), and MRX34 (a miR-34a mimic for various solid tumours). The review also covers emerging candidates like an miR-221 inhibitor and various strategies for breast cancer, such as targeting Bcl-2, KRAS, and specific miRNAs. A critical challenge across both fields is developing efficient and safe delivery systems, including lipid nanoparticles, GalNAc conjugates, and bacterial minicells. Despite promising preclinical results, clinical translation has been hampered by issues like insufficient delivery efficiency to human tumours, toxicity, and the complex, interconnected regulatory networks of miRNAs, which can lead to unpredictable off-target effects. Conclusions: While RNA therapeutics hold immense promise, overcoming delivery barriers and enhancing understanding of RNA regulatory networks are essential for future success.