ERBB2 and neoplasm: The MTD for Alp was found to be 250 mg daily (n = 17). 5 patients in cohort 1 had 2 DLTs. Median follow-up was 11.6 months (range, 0.3–19.5). Median PFS was 6 months (95% CI: 2.9–10.6). The median PFS in 11 patients without prior T-DM1 was 4.3 months (95% CI: 2.0–8.8) and in 6 patients with prior T-DM1 was 10.6 months (95% CI: 1.6–12.6). Combination of Alp 250 mg/daily + T-DM1 was considered as a safe dose in HER2+ MBC patients with prominent anti-tumor activity, even in previously treated patients with T-DM1.