Pembrolizumab (MK-3475) for patients (pts) with advanced esophageal carcinoma: Preliminary results from KEYNOTE-028.

4010 Background: Expression of the PD-1 ligands PD-L1 and PD-L2 has been associated with poor prognosis in esophageal cancer. Pembrolizumab is a highly selective humanized monoclonal antibody against PD-1 designed to block the interaction between PD-1 and PD-L1 and PD-L2. We assessed pembrolizumab safety and efficacy in pts with PD-L1+ esophageal carcinoma. Methods: KEYNOTE-028 (NCT02054806) is a nonrandomized, multicohort, phase Ib trial of pembrolizumab for PD-L1+ advanced solid tumors. Key eligibility criteria for this cohort included squamous cell carcinoma (SCC) or adenocarcinoma of the esophagus or gastroesophageal junction, measurable disease, PD-L1 expression in ≥ 1% of cells in tumor nests or PD-L1+ stromal bands determined centrally by IHC, failure of standard therapy, ECOG PS 0-1, and no autoimmune disease. Pembrolizumab 10 mg/kg is being given every 2 weeks for up to 2 years or until confirmed progression, unacceptable toxicity, or investigator decision. Response is assessed every 8 weeks for ...