TROPION-Breast01 and Comparative ADC Data

Dr. Iyengar discusses the evolving landscape since TROPICS-02 established sacituzumab govitecan (SG) as the initial ADC option after multiple chemotherapy lines, before other ADCs became available. He outlines current upfront trials including DESTINY-Breast06 (T-DXd first-line), TROPION-Breast01 (datopotamab deruxtecan [Dato-DXd] after 1-2 chemotherapy lines), TROPICS-02 (SG after multiple lines), and ASCENT-07 (SG frontline).

Dr. Nunnery explains the similarities and differences between TROPION-Breast01 and TROPICS-02, noting both agents target TROP2 with topoisomerase inhibitor payloads, creating expectations of similar efficacy that weren't realized in practice. TROPICS-02 enrolled heavily pretreated patients after at least 2 chemotherapy lines, demonstrating both progression-free survival (PFS) and overall survival (OS) improvements with SG.

TROPION-Breast01 studied Dato-DXd in less heavily pretreated patients with at least 1 prior chemotherapy line, showing significant PFS improvement but lacking OS benefit. However, crossover patterns influenced overall survival interpretation, as many patients received subsequent ADC therapy after progression, reflecting evolving standard care practices.

The OS differences between trials likely reflect treatment availability rather than drug superiority. TROPICS-02 patients couldn't access subsequent ADCs, enabling OS detection, whereas TROPION-Breast01 patients frequently received ADCs post-progression, confounding the endpoint.

Dr. Nunnery emphasizes avoiding simplistic interpretations favoring SG based solely on OS data, noting the importance of considering crossover effects and subsequent treatment access when evaluating comparative efficacy between agents.