Posted: Monday, June 12, 2023
According to Shubham Pant, MD, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues, treatment with the HER2-targeted bispecific antibody zanidatamab appeared to be safe and active in patients with refractory HER2-positive locally advanced unresectable or metastatic biliary tract cancer. The results of the phase IIb HERIZON-BTC-01 trial were presented during the 2023 American Society for Clinical Oncology (ASCO) Annual Meeting (Abstract 4008) and simultaneously published in The Lancet Oncology.
“Chemotherapy for patients with biliary tract cancers [whose disease has] progressed on first-line therapy is usually associated with a 5% response rate,” Dr. Pant commented in an MD Anderson press release. “These results provide evidence that zanidatamab can achieve durable responses and may offer a new treatment opportunity for patients who previously had limited options.”
A total of 80 patients with HER2-positive disease (cohort 1) and 7 patients with HER2-low/negative disease (cohort 2) who had received prior gemcitabine-containing therapy were administered 20 mg/kg of intravenous zanidatamab every 2 weeks. Of this population, 52% had gallbladder cancer, 30% had intrahepatic cholangiocarcinoma, and 18% had extrahepatic cholangiocarcinoma.
In cohort 1, the confirmed objective response rate was 41%; the median duration of response was 12.9 months. At data cutoff, among the 33 responders, 49% had ongoing responses, and 82% had a duration of response of at least 16 weeks. The median time to first response was 1.8 months. Evaluations of progression-free and overall survival are underway. In cohort 2, no responses were observed.
Treatment-related adverse events occurred in 72% of the overall population; diarrhea (37%) and infusion-related reactions (33%) were reported most frequently. A total of 18% of patients experienced a grade 3 treatment-related adverse event. Two patients discontinued treatment because of adverse events. Serious treatment-related adverse events were observed in seven patients. According to the investigators, there were no zanidatamab-related grade 4 adverse events or deaths in this population.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.