A Dose-Escalation Study Evaluating the Combination of Trastuzumab Emtansine (T-DM1) With Neratinib in Women With Metastatic HER2-Positive Breast Cancer

The FB-10 study is designed as an open label, single arm, Phase Ib/II study with a dose-escalation phase and an expanded cohort (phase II) to evaluate the combination of trastuzumab emtansine (T-DM1) with neratinib in women with metastatic, HER2-positive breast cancer. The primary aim of the phase Ib portion of this study is to determine the safety and tolerability of the two-drug combination. The primary aim of the phase II portion is to demonstrate efficacy. Patients will receive concurrent therapy with T-DM1 (3.6 mg/kg IV) on Day 1 of a 3-week (21 day) cycle and neratinib as a continuous daily oral dose. The neratinib dose-escalation will include 4 dose levels (120 mg, 160 mg, 200 mg, and 240 mg). At the recommended phase II dose (RP2D) of the T-DM1 and neratinib combination, up to 39 additional patients will be treated. The sample size of the phase I portion of the study was 27 patients. The sample size of the Phase II portion will be 22 evaluable patients (and 4 replacement patients). The total study enrollment, phase Ib and II, will be a maximum of 50 patients. Submission of diagnostic tumor samples and blood samples for FB-10 correlative science studies will be a study requirement for all patients. Blood samples for pharmacokinetics (PKs) and for future study will be collected prior to administration of study therapy on Cycle 1/Day 1, Cycle 1/Day 8, and Cycle 2/Day1. A tumor biopsy will be procured from an accessible site of metastasis before study therapy is initiated (after the patient has signed the consent and has been screened for eligibility).