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Zanidatamab provides ORR in HER2+ biliary tract cancer

Presented By
Prof. Funda Meric-Bernstam, University of Texas MD Anderson Cancer Center, USA
ASCO GI 2021
Phase 1

In a small number of patients in a phase 1 expansion cohort, the bispecific investigational HER2-targeted antibody zanidatamab was found to safely induce durable antitumour activity in patients with HER2-overexpressing biliary tract cancer (BTC).

Findings from the phase 1 study’s (NCT02892123) expansion cohort (n=21), testing the safety and initial efficacy of zanidatamab in patients with HER2-overexpressing BTC (representing 5-19% of BTC), were presented by Prof. Funda Meric-Bernstam (University of Texas MD Anderson Cancer Center, USA) [1]. In the dose-escalation part of the phase 1 study, the investigators reported that 20 mg/kg of zanidatamab administered every 2 weeks was the recommended dose. Tumours were imaged every 8 weeks.

Patients had a median age of 63 years, and 67% of patients were female. The most common diagnosis was gall bladder cancer (57%), followed by intrahepatic cholangiocarcinoma (24%), and extrahepatic cholangiocarcinoma (19%). In total, 24% of patients had received prior HER2-targeted therapy.

Reduction in tumour volume was observed in nearly all patients (16/20 evaluable patients), with a confirmed objective response rate of 40%, and an additional 40% achieving a partial response. The disease control rate was 65%, and the median duration of response was 7.4 months.

Zanidatamab was found to be well-tolerated. All patients experienced treatment-emergent adverse events, the most common of which were diarrhoea (43%) and infusion-related reactions (33%). No patient experienced a grade 3 or higher drug-related adverse event. Although 2 deaths were reported during the study, 1 was due to progressive disease and the other was attributed to an adverse event not related to zanidatamab.

“Based on these results, zanidatamab has the potential to address unmet needs in patients with HER2-positive biliary tract cancer,” Prof. Meric-Bernstam concluded. A phase 2b trial in second-line is in progress (NCT04466891).

  1. Meric-Bernstam F, et al. Zanidatamab (ZW25) in HER2-positive biliary tract cancers (BTCs): Results from a phase I study. ASCO Gastrointestinal Cancers Symposium 2021, 15-17 January. Abstract 299.


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