Beyond chemotherapy: Emerging biomarkers and therapies as small cell lung cancer enters the immune checkpoint era

For decades, clinicians have witnessed no therapeutic advances for small cell lung cancer, including no US Food and Drug Administration-approved targeted therapies; recently, immune-checkpoint blockade has emerged as a promising new option for the treatment of patients with relapsed small cell lung cancer (including recent US Food and Drug Administration approval of nivolumab in the third-line setting) and soon may represent the frontline standard of care in combination with chemotherapy. However, there is a need to uncover biomarkers to guide patient selection and develop novel approaches to enhance response to immunotherapies.