4-1BB Antibodies in Oncology Clinical Trials: A Review.

4-1BB is a transmembrane glycoprotein found on T lymphocytes, and signaling through 4-1BB activates and differentiates CD3+ and CD8+ T cells. The ability of 4-1BB to stimulate cytotoxic T-cell responses makes it a promising target for therapeutic cancer immunotherapy development. 4-1BB antibodies have shown promising antitumor activity in preclinical studies and clinical trials. Common side effects include transaminase elevation, cytopenias, fatigue, and nausea. This clinical review summarizes past and current 4-1BB antibodies in oncology clinical trials.