**Abstract**

Adoptive T cell therapy (ACT) is getting acknowledged as the Advanced Therapy Medicinal Products (ATMPs) in many countries and it has evolved as one of the newest regimens to treat cancer. Developed gradually by the basic understanding of cells, involved in innate and adaptive immunity, ACT has emerged as one of the successful immunotherapies in recent times. It broadly includes various cell types such as stem cells, T cells, dendritic cells and Natural Killer cells. By the applications of genetic engineering and advanced cell culture techniques, these cells from patients' blood, can be manipulated to train them for better efficacy against specific tumor cells. However, only some cells' subsets have shown promising regression for certain cancer cells types. To understand the reason behind this, technical knowledge about the tumor antigens presentation, tumor microenvironment (TME), hosts' immune responses and possible issues in the manufacturing of adoptive cellular material for infusion in patients are being explored further. This chapter brings together development of immune cells from basic research to clinical use, newer approaches which have been taken to address the resistance of ACT and future promises of this therapy.

**Keywords:** immunotherapy, advanced therapy medicinal products, adoptive T cell therapy, tumor microenvironment, TCR T cell Therapy, CAR T cell therapy
