Posted: Friday, August 4, 2023
James J. Harding, MD, of Memorial Sloan Kettering Cancer Center, New York, and colleagues recently reported results in The Lancet Oncology from a phase IIb trial examining the activity of the bispecific anti-HER2 antibody zanidatamab in patients with unresectable, locally advanced, or metastatic HER2-amplified biliary tract cancer. The trial, HERIZON-BTC-01 (ClinicalTrials.gov identifier NCT04466891), which recruited patients from nine countries, demonstrated clinical anticancer activity with this novel immunotherapy.
“Our results showed that zanidatamab is well tolerated and has an encouraging single-agent activity, both in terms of response rate and duration of response, in pretreated patients with advanced HER2-amplified biliary tract cancer,” the study authors stated.
HERIZON-BTC-01 enrolled 87 patients between September 2020 and March 2022. Patients were assigned to two cohorts, based on HER2 immunohistochemistry (IHC): cohort 1 (80 patients) had a higher concentration of HER2 (IHC 2–3+) than cohort 2 (7 patients; IHC 0–1+). All patients received zanidatamab at 20 mg/kg intravenously every 2 weeks. The primary endpoint was confirmed objective response rate (defined as the proportion of patients who received zanidatamab and had a confirmed best overall response of complete response or partial response) by independent central review for cohort 1.
Confirmed objective responses by independent central review were observed in 33 patients in cohort 1 (41.3%; 95% confidence interval = 30.4%–52.8%). At data cutoff (October 10, 2022), almost one-quarter of the patients (17 in cohort 1 and 1 in cohort 2) were still receiving treatment with zanidatamab. The median duration of follow-up was 12.4 months.
Adverse events were considered by the study authors to be manageable, with 16 patients (18%) reporting grade 3 treatment-related adverse events. No grade 4 adverse events were observed.
Disclosure: For full disclosures of the study authors, visit thelancet.com.