A dedicated, nonrandomized, crossover, sequential dose study was conducted to assess the effects of multiple doses of rifampin on the PK of a single 240 mg oral dose of neratinib (n=24). Neratinib was given on Day 1 and Day 14 with a standard breakfast, and rifampin (600 mg) was administered under fasted conditions on Days 8-15. On Day 14 neratinib 240 mg was administered with a meal one hour after rifampin. Plasma concentrations of neratinib and active metabolites M3, M6, and M7 were measured by a validated HPLC-MS/MS assay.