A Study of Alisertib in Combination With Endocrine Therapy in Patients With HR-positive, HER2-negative Recurrent or Metastatic Breast Cancer

PUMA-ALI-1201 is a randomized, dose optimization, multicenter, Phase 2 study of alisertib administered in combination with endocrine therapy in participants with pathology-confirmed HR-positive/HER2-negative metastatic breast cancer (MBC) following progression on or after at least two prior lines of endocrine therapy in the recurrent or metastatic setting. This study is intended to evaluate the optimal alisertib dose administered in combination with the selected endocrine therapy. The study is also planned to evaluate the efficacy, safety, and pharmacokinetics of alisertib in combination with endocrine and to identify the biomarker-defined subgroup(s) that may benefit most from combined alisertib and endocrine therapy. Participants randomized prior to Amendment 4 are randomized 1:1:1 to Arm 1, Arm 2 or Arm 3. Participants randomized under Amendment 4 will be randomized 1:1 to Arm 1 or Arm 2.