PALbociclib Endocrine Therapy Followed by Talazo Vs. Talazoz-Atezo Study

This trial is studying the best treatment sequence for people with metastatic (spread) breast cancer who have certain inherited gene mutations linked to DNA repair (including BRCA1/2 and related genes). Researchers are comparing different combinations of targeted therapies, including a CDK4/6 inhibitor, hormonal therapy, a PARP inhibitor, and an immunotherapy drug. **You may be eligible if...** - You have been diagnosed with metastatic (stage IV) breast cancer - You have a confirmed mutation in BRCA1, BRCA2, or one of 35 related DNA repair genes - Your breast cancer is HER2-negative - You are 19 years of age or older - You are in reasonably good health (able to care for yourself) - You have not received prior treatment for your metastatic disease **You may NOT be eligible if...** - Your breast cancer is HER2-positive - You are under 19 years old - You have received prior treatment for metastatic breast cancer - You have poor organ function Talk to your doctor to see if this trial is right for you.