Trastuzumab pamirtecan (T-Pam; BNT323/DB-1303), a HER2-targeting antibody-drug conjugate, showed promising results in patients with advanced or recurrent HER2-expressing endometrial cancer who had progressed after chemotherapy and immunotherapy.
In a phase 2 study of 145 patients with a median follow-up of 13.2 months, the treatment achieved a median progression-free survival of 8.0 months and a median overall survival of 15.0 months. The overall response rate was 44.1%, with higher responses seen in tumors with stronger HER2 expression, reaching 73.1% in IHC 3+ patients. Benefit was consistent across prior treatments, including immunotherapy, and responses were also observed in Black and African American patients.
Side effects were common, including nausea and anemia, and nearly half of patients experienced severe adverse events. Pneumonitis occurred in some patients and required careful monitoring. Despite toxicities, the findings support further evaluation in an ongoing phase 3 trial comparing the drug with standard chemotherapy.