By: Nick Turner, PhD, Senior DirectorLung cancer is the leading cause of cancer mortality worldwide, accounting for more than 1.6 million deaths annually. Non-small cell lung cancer (NSCLC) accounts for 85% of all new cases. Current first-line treatment decisions for metastatic NSCLC mandate analysis of the genetic status of the cancer to determine the presence of driver mutations, such as activating mutations in the epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK). In mutation-positive patients, first-line treatment comprises small molecule inhibitors of EGFR-tyrosine kinase, e.g., gefitinib, afatinib or osimertinib, or ALK inhibitors, e.g., alectinib or crizotinib. Roughly 85% of patients with NSCLC, however, do not harbor these oncogenic drivers; in these patients, treatment options have been limited to platinum-based chemotherapy. The emergence of immune checkpoint inhibitors, which attenuate immunosuppression within the tumor microenvironment and enable the immune system to attack tumor cells, opens the door to more effective therapy with durable responses and manageable toxicity.