In the phase IIa MyPathway [88] HER2-targeted BTC study (N = 39: n = 12 [eCCA/ampullary cancer]), BTC patients with HER2 amplification and/or overexpression (measured by next-generation sequencing, IHC ± FISH) who received pertuzumab + trastuzumab (21-day cycles) had mOS of 10.9 months (95% CI 5.2, 15.6) and mPFS of 4.0 months (95% CI 1.8, 5.7). The gene discussed is ERBB2; the disease is carcinoma of the ampulla of vater.