An age-specific pooled analysis of trastuzumab deruxtecan (T-DXd) in patients (pts) with HER2-positive (HER2+) metastatic breast cancer (mBC) from DESTINY-Breast01, -02, and -03.
1006 Background: T-DXd is approved for use in pts with HER2+ unresectable or mBC after a prior anti-HER2-based regimen in the metastatic or (neo)adjuvant setting, based on the randomized phase 3 DESTINY-Breast03 study (Cortes et al. N Engl J Med 2022). Older pts with HER2+ mBC tend to have worse efficacy and safety outcomes, regardless of treatment (Evans et al. Cancer Res 2021). Outcomes of older pts treated with T-DXd have not been thoroughly examined. Here we report age-specific (<65 vs ≥65 years) efficacy and pooled safety analyses of T-DXd from DESTINY-Breast01, DESTINY-Breast02, and DESTINY-Breast03. Methods: DESTINY-Breast01 (data cutoff [DCO], March 26, 2021) and DESTINY-Breast02 (DCO, June 30, 2022) enrolled pts whose disease progressed on trastuzumab emtansine (T-DM1); DESTINY-Breast02 compared T-DXd to chemotherapy of physician’s choice. DESTINY-Breast03 (DCO, July 25, 2022) included pts previously treated with trastuzumab and taxane; pts received either T-DXd or T-DM1. Results: At baseline, there were 44 (23.9%), 85 (20.9%), and 49 (18.8%) pts ≥65 years of age who received T-DXd in DESTINY-Breast01, DESTINY-Breast02, and DESTINY-Breast03, respectively. At DCO, median po