Novel therapies in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor of the lung with a tendency to metastasize widely early in the course of the disease. The VA staging system classifies the disease into limited stage (LS) which is confined to one hemithorax and can be included into one radiation field or extensive stage (ES) which extends beyond one hemithorax. Current standard of care is concurrent chemoradiation for LS disease and chemotherapy alone for ES disease. Only a quarter of patients with LS disease will be cured with current standard treatments and majority of the patients ultimately succumb to their disease. A very complex genetic landscape of SCLC accounts for its resistance to conventional therapy and a high recurrence rate, however, at the same time this complexity can form the basis for effective targeted therapy for the disease. In recent years, several different therapeutic strategies and targeted agents have been under investigation for their potential role in SCLC. Several of them including EGFR TKIs, BCR-ABL TKIs, mTOR inhibitors, and VEGF inhibitors have been unsuccessful in showing a survival advantage in this disease. Several others including DNA repair inhibitors, cellular developmental pathway inhibitors, antibody drug conjugates (ADCs), as well as immune therapy with vaccines, immunomodulators, and immune checkpoint inhibitors are being tested. So far, none of these agents are approved for use in SCLC and the majority are in phase I/II clinical trials, with immune checkpoint inhibitors being the most promising therapeutic strategy. In this article, we will discuss these novel therapeutic agents and currently available data in SCLC.