Primary Objective: Determine the maximum (no greater than 125 mg) dose of infigratinib used in combination with the FDA-approved dose and schedule of tamoxifen (Cohort 1) in terms of the number of dose-limiting toxicities observed in the first 2 cycles of therapy in subjects with hormone receptor-positive, HER2-negative advanced breast cancer.~Secondary Objective:~Estimate the incidence of treatment-emergent adverse events (serious and non-serious).~Estimate the objective tumor response rate (ORR) in subjects with measurable disease.~Estimate the progression-free survival (PFS).~Estimate the durable clinical benefit rate.
The purpose of the study is identify the dose(s) of infigratinib to use in combination with tamoxifen to treat patients with a particular type of advanced breast cancer (hormone receptor-positive, HER2-negative, FGFR-altered breast cancer)