Lung cancer remains the most common cancer worldwide with non-small cell lung cancer accounting for 85% of cases. Cytotoxic chemotherapy has been the mainstay of patients with NSCLC; however, survival rates remain low and toxicity is significant. Molecularly targeted therapies have proven to be superior to chemotherapy for NSCLC patients whose tumors have mutations in EGFR. Recent studies have established tyrosine kinase inhibitors (TKIs) as the gold standard for treating EGFR-mutation-positive NCSLC. However, patients on TKIs eventually progress, and in approximately 50% of cases, progression is due to development of an additional mutation called T790M. There are currently no approved therapies for patients who progress on TKIs. Rociletinib may provide an effective therapy for a patient population with few alternative treatment options. Nonclinical data demonstrate that rociletinib inhibits T790M. It is anticipated that rociletinib may promote cell death in tumor cells with the T790M mutation, thus providing possible therapeutic benefit in patients who have developed T790M-mediated resistance to first generation TKIs.