A REVIEW ON NIVOLUMAB AND BEYOND: PD-1 PATHWAY IN CANCER IMMUNOTHERAPY

The field of oncology has been drastically changed by cancer immunotherapy which makes use of the immune system to kill cancer cells. Among all the immune checkpoint pathways, the programmed cell death-1 (PD-1) and its ligands, PD-L1 and PD-L2, are the most significant ones in the immune system's regulation to some extent while at the same time receiving the most immunosuppression from the tumors. Nivolumab, a fully human IgG antibody against PD-1, is able to re-establish the function of T-cells and has a strong efficacy across various cancers, such as melanoma, non-small cell lung carcinoma, renal cell cancer, and liver cancer. The use of the drug is very effective but it does cause therapeutic resistance and immune-related side effects which are the main problems for doctors. New treatments like PD-1 inhibitors in the next generation, bispecific antibodies, and combinations along with biomarker-led personalized therapy are being investigated to improve efficacy as well as to get past resistance. In this review, the reader will find a detailed account of PD-1 biology, the mechanism of action of Nivolumab, clinical efficacy, resistance mechanisms, and future innovations, thus giving a picture of the changing landscape of PD-1-targeted cancer immunotherapy.