Advances in Cancer Immunotherapy in Solid Tumors

Immunotherapy is heralded as one of the most important advances in oncology. Until recently, only limited immunotherapeutic options were available in selected immunogenic cancers like melanoma and renal cell carcinomas. Nowadays, there is an improved understanding that anti-tumor immunity is controlled by a delicate balance in the tumor microenvironment between immune stimulatory and immune inhibitory pathways. Either by blocking the inhibitory pathways or stimulating the activating pathways that regulate cytotoxic lymphocytes, anti-tumor immunity can be enhanced leading to durable anti-tumor responses. Drugs which block the immune regulatory checkpoints namely the PD-1/PDL1 and CTLA 4 pathway have shown tremendous promise in a wide spectrum of solid and hematological malignancies, significantly improving overall survival in newly diagnosed and heavily pretreated patients alike. Hence there is renewed enthusiasm in the field of immune oncology with current research focused on augmenting responses to checkpoint inhibitors by combination therapy as well as studies looking at other immune modulators and adoptive T cell therapy. In this article, we highlight the key clinical advances and concepts in immunotherapy with particular emphasis on checkpoint inhibition as well as the future direction in this field.