The study consists of two parts and a China and Japan monotherapy cohort. Part 1 includes dose escalation cohorts evaluating PF-07220060 as single agent or in combination with endocrine therapy or enzalutamide, as well as a food effect cohort and a DDI cohort Part 2 includes dose expansion cohorts evaluating PF-07220060 in combination with endocrine therapy or enzalutamide.~In Part 1A, single escalating doses of PF-07220060 alone will be administered to determine the maximum tolerated dose (MTD) and select the recommended dose for expansion In Part 1B and Part 1C, PF-07220060 will be administered in combination with 1 of 2 endocrine therapies (letrozole and fulvestrant, respectively).~In Part 1D, food effect assessment of PF-07220060 at the RP2D dose level from the Part 1A will be conducted In Part 1E, the effect of PF-07220060 on the PK of midazolam will be evaluated (DDI) In Part 1F, escalating dosed of PF-07220060 will be administered in combination with enzalutamide Part 1B and Part 1C may commence at MTD or before reaching the MTD at a dose level in Part 1A.~Part 2A is a dose expansion cohort with fulvestrant and will explore more than one dose of PF-07220060 in participants diagnosed with mBC.~Part 2B and Part 2C are expansion for combination therapy of PF-07220060 with letrozole and fulvestrant, respectively.~Part 2D is the expansion cohort for combination therapy of PF-07220060 with enzalutamide.~The China monotherapy cohort will evaluate safety, tolerability and PK of PF-07220060 administered as single agent in Chinese participants.~The Japan monotherapy cohort will evaluate safety, tolerability and PK of PF-07220060 administered as a single agent in Japanese participants.
This is a Phase 1/2A, open label, multicenter, nonrandomized, multiple dose, safety, tolerability, pharmacokinetic and pharmacodynamic study of PF-07220060 administered as a single agent and then in combination with endocrine therapy.