T-DM1 Hits 88% Response in HER2-Amplified Salivary Gland Cancers in Basket Trial

Ado-trastuzumab emtansine (T-DM1), an HER2-targeted antibody–drug conjugate approved for breast cancer, was tested in a single-arm Phase 2 basket study (NCT02675829) enrolling 88 patients with HER2-amplified NSCLC, colorectal, endometrial, salivary gland, or other solid tumors. Given at 3.6 mg/kg IV every 3 weeks, ORR reached 87.5% (14/16) in salivary gland tumors but only 22% in NSCLC (4/19), 22% in endometrial (5/23), 9% in “other” tumors, and 0% in colorectal cancer, yielding an overall RECIST ORR of 23.5%; median time on therapy was 17.6 months for salivary gland cases versus 2.5 months overall. Thrombocytopenia and transaminitis were common, and one fatal grade-5 pneumonitis was reported.