Purpose: Cytotoxic T lymphocyte antigen 4 (CTLA4), a key negative regulator of T-cell activation, is targeted by the antibody tremelimumab to release potentially useful antitumor activity.
Experimental Design: This phase II trial investigated tremelimumab as a second-line treatment for patients with metastatic gastric and esophageal adenocarcinomas. Tremelimumab was given every 3 months until symptomatic disease progression.