Fixed-Dose SC Pertuzumab/Trastuzumab Delivers 94% 3-Year IDFS in Early HER2+ Breast Cancer

In the randomized phase II PHranceSCa crossover trial (NCT03674112), 159 adjuvant HER2-positive early-stage patients received three cycles of a fixed-dose subcutaneous pertuzumab-trastuzumab combo (PH FDC SC) and three cycles of standard IV administration of the same combination, then continued their preferred route for up to 18 cycles. At 3 years, invasive disease-free survival was 94.17% (95% CI 90.5–97.9) and overall survival 98.71%, mirroring the 94.1% 3-year IDFS seen with IV dual blockade in the phase III APHINITY study. Safety remained mostly grade 1/2; injection-site reactions occurred in 9%, two low-grade cardiac events and three hypersensitivity events were reported, and no grade ≥3 anaphylaxis or new toxicities emerged.