185O Trastuzumab deruxtecan (T-DXd) vs treatment of physician’s choice (TPC) in patients (pts) with HER2-low unresectable and/or metastatic breast cancer (mBC): A detailed safety analysis of the randomized, phase III DESTINY-Breast04 trial
H. S. Rugo, William Jacot, Eriko Tokunaga, Joohyuk Sohn, Fátima Cardoso, Binghe Xu, M.J. Vidal Losada, M.J. Gil, Naoto T. Ueno, Aleix Prat, Halle C. F. Moore, Ursula Hasler-Strub, David Cameron, Henrik Lindman, K. Mezei, Rajaganesh Rajagopalan, Cecilia Orbegoso, F-C. Cheng, Adeep Puri, Shanu Modi
Abstract
DESTINY-Breast04 (NCT03734029) demonstrated significantly improved overall and progression-free survival (PFS) with T-DXd vs TPC in pts with HER2-low (immunohistochemistry [IHC] 1+ or IHC 2+/in situ hybridization-negative) mBC, with manageable safety. Here, we report additional safety data. Pts with centrally confirmed HER2-low mBC, treated with 1-2 prior lines of chemotherapy, were randomly assigned 2:1 to receive T-DXd or TPC. An analysis of selected treatment-emergent adverse events (TEAEs) and age (<65 vs ≥65 years [y]) was done; endpoints included time to first onset (TTO), duration of first event (DUR), and resolution. At data cutoff (January 11, 2022), median (m) treatment duration was 8.2 months (mo; range [r], 0.2-33.3) for T-DXd vs 3.5 mo (r, 0.3-17.6) for TPC. Exposure-adjusted incidence rates (EAIRs; per pt-y) for any-grade TEAEs were lower for T-DXd vs TPC (1.30 vs 2.66). mTTO and mDUR of any-grade interstitial lung disease (ILD) in pts treated with T-DXd were 129 days (d; r, 26-710 d) and 47 d (r, 13-365 d). 13 pts had adjudicated drug-related grade 1 ILD; of those pts, 6 were rechallenged with T-DXd after resolution (details to be presented). Incidence of any-grade drug-related neutropenia (NP) and febrile NP was lower for T-DXd vs TPC; subsequent granulocyte colony-stimulating factor use was 6.7% vs 19.8%. Nausea/vomiting (N/V) events in T-DXd vs TPC were 79.5% vs 35.5%. T-DXd-treated pts received more antiemetic prophylaxis (AP; 50.9%) vs TPC-treated pts (37.2%); 92.3% of T-DXd and 68.8% of TPC N/V events in AP-treated pts resolved. Incidence of any-grade drug-related TEAE was consistent between pts aged <65 y and ≥65 y. For T-DXd, incidence of grade ≥3 TEAEs and TEAEs associated with drug discontinuations (DD) was higher in pts aged ≥65 y compared to those aged <65 y; the most common TEAE associated with DD was ILD/pneumonitis. However, mPFS favored T-DXd over TPC in all patients, regardless of age. EAIR, TTO, and DUR data for selected TEAEs will be presented. T-DXd demonstrated a manageable safety profile to support its use as the new standard of care in pts with HER2-low mBC.