Immunotherapy in small-cell lung cancer: at what point are we?

Immunotherapy is a new frontier for the management of cancers with practice-changing trials already reported for unresectable or metastatic malignant melanoma, advanced non-small-cell lung cancer (NSCLC), and advanced renal-cell carcinoma (1). Considering these recent exciting developments, immunotherapy is being investigated in small-cell lung cancer (SCLC), too. Unfortunately, in the last decades, despite several treatment attempts and new strategic approaches investigated, SCLC outcomes have not improved. In fact, even if an objective response rate (ORR) with first-line chemotherapy was reached by most of the patients, they relapse within a year of treatment. At relapse, the response to first-line chemotherapy and its duration are the main factors in predicting the efficacy of salvage chemotherapy. In fact, based on these two factors patients who respond to initial chemotherapy and relapse more than 60–90 days after the end of chemotherapy are defined as ‘sensitive relapse’ patients, while those whose tumor is stable or progresses during the initial chemotherapy or who have a recurrence within 60–90 days after the end of chemotherapy are considered ‘refractory relapse’ patients (2).