PH FDC SC (pertuzumab+trastuzumab) dual-HER2 blockade matches IV outcomes at 4 years in early breast cancer

PH FDC SC is a fixed-dose, subcutaneous co-formulation of pertuzumab (HER2 dimerization inhibitor) and trastuzumab (anti-HER2 mAb) designed to replace IV dosing while preserving exposure; in the Phase III FeDeriCa trial (NCT03493854), patients with HER2-positive early breast cancer were randomized 1:1 to neoadjuvant chemo + IV pertuzumab/trastuzumab vs PH FDC SC every 3 weeks (with adjuvant HER2 therapy continued to complete 18 cycles). At the 2 June 2023 data cut-off with ~51-month median follow-up, 4-year invasive disease-free survival was 89.6% (IV) vs 88.5% (SC) and 4-year overall survival was 95.5% vs 94.1%, with similarly close results for EFS and distant recurrence-free interval; no new safety signals emerged, including no new cardiac safety concerns. Clinically, the long-term outcomes appear in-family with what’s expected for modern pertuzumab+trastuzumab-based early-stage management (e.g., adjuvant pertuzumab benefit in higher-risk disease; node-positive 6-year iDFS ~88% with pertuzumab vs ~83% control in APHINITY), supporting SC delivery as a convenience switch rather than an efficacy play.