Shifting tides from non-targeted chemotherapy to targeted therapies and small RNA-based bio drugs: A changing paradigm in cancer therapy.

Ever since its discovery in the early 20th century, chemotherapy has been the mainstream therapy for almost all cancers. Though several cycles of chemotherapy significantly reduce the proliferation and spread of the disease, they cause deleterious side effects. The adverse effects on the immune system imposed by these non-specific cytotoxic chemo drugs forced scientists to focus and give importance to boosting the immune system with a series of specific biological therapies. Stimulating or modulating the immune system to recognize and strike cancer cells (immunotherapy), combining with the application of gene knock down through RNA interference (RNAi) have spearheaded the cancer biotherapies, propelling them towards a more targeted and efficacious therapy regimen. Immunotherapy uses drugs like monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor (CAR)-T cell therapy to enhance the immune response. These immune-based therapies can improve the specificity of cancer targeting and overcome immune evasion mechanisms employed by cancer cells. Further, soon after RNAi discovery, efforts have been made to adopt RNAi for its clinical applications in treating cancer. Different non-coding RNAs (ncRNAs) exert a distinct influence on gene expression and its regulation, offering a diversified toolkit for manipulating cellular pathways in the fight against cancer. This review article summarizes the currently used chemo drugs and their adverse effects and the shift of focus towards small RNA based bio-drugs as future cancer therapeutics.