Dr Pant on the Utility of Zanidatamab in Previously Treated HER2+ Biliary Tract Cancer

Shubham Pant, MD, MBBS, professor, Department of Gastrointestinal Medical Oncology, Department of Investigational Cancer Therapeutics (Phase I Center), The University of Texas MD Anderson Cancer Center, discusses the utility of zanidatamab in patients with previously treated HER2-positive biliary tract cancer.

At the 2024 ASCO Annual Meeting, investigators presented updated results from the phase 2b HERIZON-BTC-01 study (NCT04466891) investigating zanidatamab in patients with previously treated HER2-positive biliary tract cancer. After a median follow-up of 22 months (range, 16-34), zanidatamab elicited a confirmed overall response rate (cORR) of 41.3%, a disease control rate of 68.8%, and a median overall survival (OS) of 15.5 months (95% CI, 10.4-18.5). Notably, the safety profile remained consistent with prior data readouts with the agent, with few treatment-related adverse effects (AEs) leading to dose reduction.

Previous data from this global trial in patients with HER2-positive advanced biliary tract cancers were shared in 2023. The trial focused on these patients exclusively and involved administering zanidatamab intravenously every 2 weeks, Pant begins, saying that investigators evaluated the ORR and progression-free survival. In 2023, investigators reported a cORR of 41.3%, which is significantly higher than the approximately 5% ORR historically seen with FOLFOX, an unselected second-line treatment for biliary tract cancer, Pant explains. The initial duration of response (DOR) with zanidatamab was approximately 12.9 months, indicating that patients responded well to the agent and maintained their response for a considerable period, he states.

In 2024, investigators provided an updated follow-up, showing that the median DOR with the agent had increased, with the ORR remaining stable at 41.3%, Pant reports. Additionally, the median OS for these patients was reported to be 15.5 months, reflecting an extended benefit from the therapy, he shares.

Moreover, investigators found that long-term AEs remained consistent with previous findings, with no new safety signals emerging, Pant expands. These results highlight the significant and sustained efficacy of zanidatamab for patients with advanced HER2-positive biliary tract cancers, demonstrating improved DOR and OS vs FOLFOX, he concludes.