Pembrolizumab, a humanized IgG4 antibody against PD-1, was initially approved by the FDA in September 2014 following results from the KEYNOTE-001 clinical trial (NCT01295827), studying patients with unresectable or metastatic melanoma and patients with non-small cell lung cancer (NSCLC). The gene discussed is PDCD1; the disease is metastatic melanoma.