Novel approaches in cancer immunotherapy -- a light at the end of the tunnel.

After decades of disappointments, the use of immunotherapy in cancer has finally come of age and resulted in a real paradigm shift in cancer treatment across many tumor types. With the advent of novel immunotherapies based on increasing understanding of the human immune system, cure has become a real possibility for many patients. The development of cancer vaccines, immune checkpoint inhibitors, chimeric antigen receptor T cell, oncolytic virus based immunotherapy to name a few have given hope to patients. One of the most exciting developments in the era of immunotherapy has been the discovery of checkpoint inhibitors causing blockade of two important immune pathways -- cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death receptor-1 (PD-1), resulting in empowerment of anti-tumor immunity. However, only a select group of patients respond to these immunotherapies, highlighting a need for novel strategies that could help transform the non-responders to responders' category. This article highlights various immunotherapeutic agents and strategies using them and other modalities in the treatment of solid tumors.