Combination pertuzumab and trastuzumab can produce durable responses in previously treated patients with HER2-positive metastatic biliary tract cancer, according to trial results published in The Lancet Oncology.

The MyPathway trial (ClinicalTrials.gov Identifier: NCT02091141) is an ongoing, phase 2 basket trial designed to evaluate the activity of approved therapies in non-indicated tumors with potentially actionable genetic alterations.

Researchers reported phase 2a results from 39 patients with HER2-positive metastatic biliary tract cancers treated with pertuzumab and trastuzumab.


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The patients received pertuzumab (840 mg loading dose, then 420 mg every 3 weeks) and trastuzumab (8 mg/kg loading dose, then 6 mg/kg every 3 weeks) until disease progression or unacceptable toxicity.

The median number of treatment cycles was 6 (range, 2-12), and the median follow-up was 8.1 months.

The objective response rate was 23%, with no complete responses. The median duration of response was 10.8 months. The disease control rate was 51%, with 28% of patients having stable disease for more than 4 months.

The median progression-free survival was 4.0 months, and the median overall survival was 10.9 months.

The treatment was well tolerated, according to the researchers. Grade 3-4 treatment-emergent adverse events (AEs) occurred in 46% of patients, and serious treatment-emergent AEs were reported in 26%.

There were no grade 4-5 or serious AEs that were considered related to treatment. Grade 3 treatment-related AEs occurred in 3 patients and included elevated alanine aminotransferase, aspartate aminotransferase, blood alkaline phosphatase, and blood bilirubin.

“Results from MyPathway, previous clinical trials, and anecdotal reports support the consideration of HER2-targeted therapy in patients with previously treated HER2-positive advanced biliary tract cancer, a historically difficult-to-treat population,” the researchers wrote. “The response rate is promising for the initiation of randomized controlled trials of pertuzumab plus trastuzumab in this patient population.”

Disclosures: This research was supported by F Hoffmann-La Roche/Genentech. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Javle M, Borad MJ, Azad NS, et al. Pertuzumab and trastuzumab for HER2-positive, metastatic biliary tract cancer (MyPathway): A multicentre, open-label, phase 2a, multiple basket study. Lancet Oncol. Published online July 30, 2021. doi:10.1016/S1470-2045(21)00336-3

This article originally appeared on Cancer Therapy Advisor