A Study to Learn About a New Medicine Called ARV-471 (PF-07850327) in People Who Have Advanced Metastatic Breast Cancer.

A study to learn about a new medicine called ARV-471 (PF-07850327) in people who have advanced metastatic breast cancer.

Inclusion Criteria:Adult participants with loco-regional recurrent or metastatic breast disease not amenable to surgical resection or radiation therapyConfirmed diagnosis of ER+/HER2- breast cancerPrior therapies for locoregional recurrent or metastatic disease must fulfill all the following criteria:One line of CDK4/6 inhibitor therapy in combination with endocrine therapy≤ 1 endocrine therapy in addition to CDK4/6 inhibitor with ETMost recent endocrine treatment duration must have been given for ≥6 months prior to disease progressionRadiological progression during or after the last line of therapyMeasurable disease evaluable per Response Evaluation Criterion in Solid Tumors (RECIST) v.1.1 or non-measurable bone-only diseaseEastern Cooperative Oncology Group (ECOG) performance status 0-1Participants should be willing to provide blood and tumor tissueExclusion Criteria:Participants with advanced, symptomatic visceral spread, that are at risk of life-threatening complications in the short termPrior treatment with:ARV-471, fulvestrant, mTOR, PI3K, AKT pathway inhibitors, PARP inhibitor for any settingother investigational novel endocrine therapy (ie, SERD, SERCA, CERAN) for any settingprior CDK4/6 inhibitor treatment in the neoadjuvant/ adjuvant settingprior chemotherapy for advanced/metastatic diseaseInadequate liver, kidney and bone marrow functionActive brain metastasesParticipants with significant concomitant illness