Zanidatamab Yields Durable Responses in HER2+ Biliary Tract Cancer

Zanidatamab, a HER2-targeted bispecific antibody, can produce rapid and durable responses in patients with advanced HER2-positive biliary tract cancer, according to research presented at the ASCO Annual Meeting 2023.

All subtypes of biliary tract cancer — gallbladder cancer, intrahepatic cholangiocarcinoma, and extrahepatic cholangiocarcinoma — seemed to benefit from zanidatamab, said Shubham Pant, MD, of MD Anderson Cancer Center in Houston.

Dr Pant presented these findings, from the phase 2b HERIZON-BTC-01 trial (ClinicalTrials.gov Identifier: NCT04466891), at the meeting. 

He reported on 80 patients with HER2-positive, locally advanced or metastatic biliary tract cancer that was previously treated with gemcitabine-containing therapy. The patients had received a median of 1 prior therapy in the advanced/metastatic setting (range, 1-7). 

The patients’ median age at baseline was 64 (range, 32-79) years, 56.3% of patients were women, 65% were Asian, and 88.8% had stage IV disease. Most patients had gallbladder cancer (51.3%), followed by intrahepatic cholangiocarcinoma (28.8%) and extrahepatic cholangiocarcinoma (20.0%).  

The patients received zanidatamab at 20 mg/kg intravenously every 2 weeks. The median duration of treatment was 5.6 months, and the median follow-up was 12.4 months. 

The confirmed overall response rate by independent central review was 41.3%. Responders included 1 patient who achieved a complete response and 32 who had partial responses. The disease control rate was 68.8%. 

The median time to first response was 1.8 months, and the median duration of response was 12.9 months. The median progression-free survival was 5.5 months, and overall survival data are not yet mature.

Treatment-related adverse events (TRAEs) were reported in 76.3% of patients. Common TRAEs included diarrhea (40.0%), infusion-related reactions (35.0%), ejection fraction decrease (10.0%), and nausea (10.0%). 

There were no fatal TRAEs, but there were 2 TRAEs that led to treatment discontinuation (grade 2 ejection fraction decrease and grade 3 pneumonitis). 

“These results support zanidatamab having meaningful clinical benefit and potential as a future treatment option in HER2-positive BTC [biliary tract cancer],” Dr Pant said.

Reference

Pant S, Fan J, Oh DY, et al. Results from the pivotal phase (Ph) 2b HERIZON-BTC-01 study: Zanidatamab in previously-treated HER2‑amplified biliary tract cancer (BTC). ASCO 2023. June 2-6, 2023. Abstract 4008. 

This article originally appeared on Cancer Therapy Advisor