Neratinib 240 mg was determined to be the MTD and the recommended dose for the expanded MTD cohort as there were grade 2 diarrhea, grade 3 diarrhea, and grade 3 anorexia were reported as DLTs for 2 subjects in the neratinib 320-mg cohort and no subjects in the neratinib 80-mg, 160-mg, and 240-mg cohorts had DLTs. The primary DLT, diarrhea, was managed with clinical intervention, that may in elude an tidiarrheal medicati on, dose reducti on, an d/or temporary dose interruption.