Trastuzumab Deruxtecan with Nivolumab in HER2-Expressing Metastatic Breast or Urothelial Cancer: Analysis of the Phase Ib DS8201-A-U105 Study.

Purpose: This multicenter phase Ib study investigated trastuzumab deruxtecan (T-DXd) plus nivolumab in patients with HER2-expressing metastatic breast cancer (mBC) and metastatic urothelial cancer (mUC).

Patients And Methods: Part 1 determined the recommended dose for expansion of T-DXd plus nivolumab. Part 2 evaluated efficacy and safety; the primary endpoint was confirmed objective response rate by independent central review.