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 3 DESTINY-Breast04 trial

Background

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.

Methods

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.

Results

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.

Conclusions

T-DXd demonstrated a manageable safety profile to support its use as the new standard of care in pts with HER2-low mBC.

Clinical trial identification

NCT03734029.

Editorial acknowledgement

Under the guidance of authors, assistance in medical writing and editorial support was provided by Elize Wolmarans, PhD, and Soniya Patel, PhD, of ApotheCom, and was funded by Daiichi Sankyo, Inc.

Legal entity responsible for the study

Daiichi Sankyo, Inc., and AstraZeneca.

Funding

This study was funded by Daiichi Sankyo, Inc., and AstraZeneca.

Disclosure

H.S. Rugo: Financial Interests, Personal, Advisory Role, Consultancy: Puma, NAPO, Blueprint, Scorpion Therapeutics; Financial Interests, Personal, Invited Speaker, Travel Expenses, including accommodations: Merck, AstraZeneca, Gilead; Other, Institutional, Research Grant: Astellas Pharma Inc., AstraZeneca, Daiichi Sankyo, Inc., F. Hoffmann-La Roche AG/Genentech Inc., Gilead Sciences, Inc., GlaxoSmithKline, Lilly, Merck & Co., Inc., Novartis Pharmaceuticals Corporation, OBI Pharma, Pfizer, Pionyr Immunotherapeutics, Sermonix Pharmaceuticals Inc., Taiho Oncology, Inc., Veru Inc. W. Jacot: Financial Interests, Personal, Advisory Board: AstraZeneca, Eisai, Novartis, Roche, Pfizer, Eli Lilly, MSD, BMS, Chugai, Seagen, Daiichi Sankyo; Financial Interests, Personal, Invited Speaker: AstraZeneca, Pfizer, Seagen, Daiichi Sankyo; Financial Interests, Institutional, Research Grant: AstraZeneca, Daiichi Sankyo; Financial Interests, Invited Speaker: Roche, Novartis, Daiichi Sankyo, Daiichi Sankyo. E. Tokunaga: Financial Interests, Personal, Speaker’s Bureau: AstraZeneca, Eli Lilly, Daiichi Sankyo. J. Sohn: Financial Interests, Personal, Stocks/Shares: Daiichi Sankyo; Financial Interests, Personal, Research Grant: Seagen, MSD, Roche, Novartis, AstraZeneca, Lilly, Pfizer, GlaxoSmithKline, Daiichi Sankyo, Inc., Sanofi, Boehringer Ingelheim. F. Cardoso: Financial Interests, Personal, Other, Consultancy: Amgen, Astellas/Medivation, AstraZeneca, Celgene, Daiichi Sankyo, Eisai, GE Oncology, Genentech, GlaxoSmithKline, Macrogenics, Medscape, Merck-Sharp, Merus BV, Mylan, Mundipharma, Novartis, Pfizer, Pierre-Fabre, Prime Oncology, Roche, Sanofi, Samsung Bioepis, Seagen, Teva; Financial Interests, Personal, Advisory Board: Gilead, Iqvia, Touchime; Financial Interests, Institutional, Invited Speaker: Amgen, AstraZeneca, Boehringer-Ingelheim, Bristol Myers Squibb, Bayer, Daiichi, Eisai, Fresenius GmbH, Genentech, GlaxoSmithKline, Ipsen, Incyte, Nektar Therapeutics, Nerviano, Novartis, Macrogenics, Medigene, MedImmune, Merck, Millenium, Pfizer, Pierre-Fabre, Roche, Sanofi-Aventis, Sonus, Taiho Oncology, Tesaro, Tigris, Wilex, Wyeth, Gilead; Non-Financial Interests, Leadership Role, President: ABC Global Alliance and ABC Consensus Conference and Guidelines; Non-Financial Interests, Member: ESMO, ESO, EORTC, BCG, IBCSG, SOLTI, ASCO, AACR, EACR, SIS, ASPIC. B. Xu: Financial Interests, Personal, Advisory Board: Novartis, AstraZeneca; Financial Interests, Personal, Invited Speaker: Pfizer, Roche; Financial Interests, Institutional, Research Grant: Henrui. M.J. Gil: Financial Interests, Personal, Invited Speaker, Honoraria: AstraZeneca, Novartis, Pfizer, Pierre-Fabre, Roche; Financial Interests, Personal, Advisory Role, Advisory/ Consultancy: Daiichi Sankyo, Seagen, Gilead; Financial Interests, Personal, Advisory Board, Travel Expenses, including accommodations: Daiichi Sankyo, Pfizer. A. Prat: Financial Interests, Personal, Invited Speaker: Roche; Financial Interests, Personal, Invited Speaker, Lecture fees: Novartis, Daiichi Sankyo; Financial Interests, Personal, Advisory Board, Advisory role/consultancy: Novartis, Pfizer, BMS, Puma, Oncolytics Biotech, MSD, Guardant Health, Peptomyc; Financial Interests, Institutional, Invited Speaker, Clinical trials: Daiichi Sankyo; Financial Interests, Institutional, Other, Contracted research: Boehringer, Medica Scientia inno. Research; Financial Interests, Personal, Advisory Board: AstraZeneca; Financial Interests, Personal, Invited Speaker, Leadership role: Reveal Genomics, SL.; Financial Interests, Personal, Stocks/Shares: Reveal Genomics, Oncolytics Biotech; Financial Interests, Personal, Royalties: Reveal Genomics; Financial Interests, Institutional, Invited Speaker: Roche, AstraZeneca, Novartis; Financial Interests, Personal and Institutional, Invited Speaker: Daiichi Sankyo; Non-Financial Interests, Institutional, Other, Leadership roles: Patronage committee: SOLTI Foundation, Actitud Frente al Cáncer Foundation. H. Moore: Financial Interests, Personal, Advisory Role, Consulting Fees: Myovant; Financial Interests, Institutional, Research Grant: AstraZeneca, Roche, Daiichi Sankyo, Sermonic, Seagen. U. Hasler-Strub: Financial Interests, Personal, Other, Travel Expenses, including accommodations: Daiichi Sankyo. D.A.A. Cameron: Financial Interests, Personal, Advisory Role, Consultancy: Seagen, Daiichi Sankyo, AstraZeneca, Synthon, Novartis, GSK. H. Lindman: Financial Interests, Personal, Invited Speaker, Honoraria: Lilly, AstraZeneca, Daiichi Sankyo, Pierre Fabre; Financial Interests, Personal, Advisory Role, Consultancy: Lilly, MSD, Daiichi Sankyo, Novartis, Seagen, Gilead, AstraZeneca; Financial Interests, Personal, Research Grant: Roche. R. Rajagopalan, C.M.A. Orbegoso, F. Cheng, A. Puri: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo. S. Modi: Financial Interests, Personal, Advisory Board: Daiichi Sankyo, Genentech, AstraZeneca, Seagen, Macrogenics; Financial Interests, Personal, Invited Speaker: Daiichi Sankyo, AstraZeneca, Daiichi Sankyo; Financial Interests, Institutional, Invited Speaker: Daiichi Sankyo, Genentech, AstraZeneca, Seagen. All other authors have declared no conflicts of interest.