Complete response to pembrolizumab in a patient with extensive-stage small-cell lung cancer: a case report

Small cell lung cancer (SCLC) is an invasive lung cancer subtype. Despite its sensitivity to first-line chemotherapy, SCLC has a high recurrence rate and poor response to second-line therapy. Recently, immunotherapy has shown promise as a novel therapy for the treatment of SCLC. One immune-checkpoint inhibitor, pembrolizumab, has demonstrated antitumor activity in patients with SCLC. In June 2019, based on data from the KEYNOTE-28 and KEYNOTE-158 trial, the US Food and Drug Administration (FDA) approved pembrolizumab for treatment of metastatic SCLC patients who had made progress on a platinum-based chemotherapy and at least one other line of therapy. Herein, we reported an 86-year-old female patient with extensive-stage disease (ED-SCLC) who was treated with pembrolizumab after relapse following first-line therapy and achieved a complete response (CR) in only one month after initiation of treatment. This case highlights that patients with ED-SCLC may benefit from immunotherapy and identifies a clinically meaningful therapeutic option.