Cell-based immunotherapy with cytokine-induced killer (CIK) cells: From preparation and testing to clinical application.

Cell-based immunotherapy holds promise in the quest for the treatment of cancer, having potential synergy with surgery, chemotherapy and radiotherapy. As a novel approach for adoptive cell-based immunotherapy, cytokine-induced killer (CIK) cells have moved from the 'bench to bedside'. CIK cells are a heterogeneous subset of ex-vitro expanded, polyclonal T-effector cells with both natural killer (NK) and T-cell properties, which present potent non-major histocompatibility complex-restricted cytotoxicity against a variety of tumor target cells. Initial clinical studies on CIK cell therapy have provided encouraging results and revealed synergistic antitumor effects when combined with standard therapeutic procedures. At the same time, issues such as inadequate quality control and quantity of CIK cells as well as exaggerated propaganda were continuously emerging. Thus, the Ministry of Health in China stopped CIK cell therapy in May 2016, which was a major setback for the innovation of CIK cell-based immunotherapy. Thus, it is very important to modify technical criteria to develop a standardized operation procedure (SOP) and standardized system for evaluating antitumor efficacy in a safe way.