Phase 2 trial of patritumab deruxtecan for HR-positive, HER2-negative advanced breast cancer

The phase 2 ICARUS-BREAST01 trial, at Gustave Roussy (Villejuif, France) evaluated patritumab deruxtecan (HER3-DXd) among patients with HR-positive, HER2-negative metastatic breast cancer after progression on CDK4/6 inhibitors. The trial met its primary endpoint, showing an overall response rate of 53.5% (90% CI 44.8-62.1). The most frequent adverse events were fatigue (83%), nausea (75%), diarrhea (43%), and alopecia (40%). Exploratory analyses suggested associations between ORR and both HER3 spatial distribution and absence of ESR1 mutations, as well as between progression-free survival and HER3 expression. The authors conclude that HER3-DXd showed promising activity and manageable tolerability of patritumab deruxtecan among patients with HR+ HER2- mBC after progression on CDK4/6 inhibitors.