Apo2L/TRAIL and the Death Receptor 5 Agonist Antibody AMG 655 Cooperate to Promote Receptor Clustering and Antitumor Activity

Death receptor agonist therapies have exhibited limited clinical benefit to date. Investigations into why Apo2L/TRAIL and AMG 655 preclinical data were not predictive of clinical response revealed that coadministration of Apo2L/TRAIL with AMG 655 leads to increased antitumor activity in vitro and in vivo. The combination of Apo2L/TRAIL and AMG 655 results in enhanced signaling and can sensitize Apo2L/TRAIL-resistant cells. Structure determination of the Apo2L/TRAIL-DR5-AMG 655 ternary complex illustrates how higher order clustering of DR5 is achieved when both agents are combined. Enhanced agonism generated by combining Apo2L/TRAIL and AMG 655 provides insight into the limited efficacy observed in previous clinical trials and suggests testable hypotheses to reconsider death receptor agonism as a therapeutic strategy. •Apo2L/TRAIL and AMG 655 show superior tumor cell killing over either agent alone•Cells resistant to soluble Apo2L/TRAIL are sensitized by the combination•The X-ray structure of the complex provides a model of higher order clustering•Apo2L/TRAIL and a DR5 antibody demonstrate a therapeutic window in syngeneic models Death receptor (DR) agonist therapies have not shown clinical benefit. Graves et al. show that Apo2L/TRAIL together with the DR agonist antibody AMG 655 form higher order clustering with DR5 and have stronger antitumor activity than either alone, providing insight into DR agonism therapy improvement.