C4391024: "AN INTERVENTIONAL, OPEN-LABEL, RANDOMIZED, MULTICENTER PHASE 3 STUDY OF PF-07220060 PLUS LETROZOLE COMPARED TO CDK4/6 INHIBITOR PLUS LETROZOLE IN PARTICIPANTS OVER 18 YEARS OF AGE WITH HORMONE RECEPTOR (HR)-POSITIVE, HER2-NEGATIVE ADVANCED/METASTATIC BREAST CANCER WHO HAVE NOT RECEIVED ANY PRIOR SYSTEMIC ANTICANCER TREATMENT FOR ADVANCED/METASTATIC DISEASE (FOURLIGHT-3)"

The purpose of this study is to compare the effects of the study drug PF-07220060 plus letrozole on your body with a comparison drug (palbociclib, ribociclib, or abemaciclib) plus letrozole, to find out which is better for treating your type of breast cancer. The study drug is an investigational drug because it is not approved for use in breast cancer treatment. The comparison drug is already approved to treat HR+, HER2- advanced or metastatic breast cancer. Researchers will compare the results of taking the comparison drug (palbociclib, ribociclib, or abemaciclib) plus letrozole to the results of taking the study drug plus letrozole to see if there are any differences.