A new hope: the immunotherapy in small cell lung cancer.

Small cell lung cancer (SCLC) is of a high-grade malignancy with a high metastatic potential and poor clinical prognosis. Unfortunately, SCLC initially exhibits a good response to chemotherapy and radiation therapy, but inevitably, relapses decrease patients' chance of survival. Despite tremendous advances on the development of new chemotherapeutic agents, the prognosis of this disease remains poor. Immunotherapy plays a role in eliciting an anticancer response by modulating the patient's immune response of the tumor. Several studies have demonstrated that abnormal autoimmune regulation has a close relationship with SCLC. Thus, several immunotherapy trials are focused on SCLC treatment, including such approaches as immune checkpoints blockers, tumor vaccine, antigenic targets and adoptive cellular immunotherapy to benefit patients with SCLC. To date, the results from immunotherapy in SCLC have not been promising. For example, tumor vaccines have not been demonstrated to have a significant survival benefit. However, there have been many promising advances with immune checkpoints blockers. This review will provide a general overview of immunotherapy in SCLC. The landmark clinical trials in previous successful immunotherapy studies are summarized here. Finally, the challenges of immunotherapy in SCLC are discussed to facilitate the prediction of possible and valuable strategies for future therapy.