Patients with activating somatic HER2 mutations with different histologies, including BTC, received neratinib monotherapy….Confirmed ORR in 25 evaluable patients was 12% (95% CI 3–31%) and CBR was 20% (95% CI 7–41%), including 3 confirmed PRs and 2 patients with SD for =16 weeks....Tumor shrinkage was observed in multiple HER2-activating mutations....Median PFS was 2.8 (95% CI 1.1–3.7) months; median overall survival (OS) was 5.4 (95% CI 3.7–11.7) months.