Apo2L/TRAIL and AMG 655 show superior tumor cell killing over either agent alone
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Cells resistant to soluble Apo2L/TRAIL are sensitized by the combination
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The X-ray structure of the complex provides a model of higher order clustering
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Apo2L/TRAIL and a DR5 antibody demonstrate a therapeutic window in syngeneic models
Summary
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.