Pertuzumab and trastuzumab for HER2-positive, metastatic biliary tract cancer (MyPathway): a multicentre, open-label, phase 2a, multiple basket study

MyPathway is a non-randomised, multicentre, open-label, phase 2a, multiple basket study of approved therapies in non-indicated tumours with actionable alterations. Patients aged 18 or older with previously treated metastatic biliary tract cancer with HER2 amplification, overexpression or both and ECOG performance status 0 to 2 were enrolled at 23 United States sites and received pertuzumab (840 mg loading, then 420 mg every 3 weeks) plus trastuzumab (8 mg/kg loading, then 6 mg/kg every 3 weeks). The primary endpoint was investigator-assessed objective response rate by RECIST 1.1.

39 patients enrolled between October 2014 and May 2019 were evaluable at the March 2020 cut-off (median follow-up 8.1 months). Nine of 39 achieved a partial response (objective response rate 23%, 95% CI 11 to 39). Grade 3 to 4 treatment-emergent adverse events occurred in 18 (46%) of 39, most commonly raised alanine and aspartate aminotransferase (13% each); treatment-related grade 3 events in 3 (8%); no treatment-related serious adverse events, grade 4 events or deaths.