Randomized Study of Talazoparib Versus Talazoparib Plus Atezolizumab After Palbociclib Endocrine Therapy for Premenopausal HR+/HER2- Metastatic Breast Cancer with HRD Scar

What this Trial Is About

Researchers are evaluating treatments for premenopausal women with metastatic breast cancer that is hormone receptor-positive and HER2-negative, and who have specific genetic alterations related to homologous recombination deficiency. This phase II randomized study compares talazoparib alone versus talazoparib combined with atezolizumab for second-line treatment following initial therapy including palbociclib, endocrine treatment, and GnRH agonist. The study aims to understand the progression-free survival during the second-line treatment over up to 72 months. The study begins with first-line treatment where participants receive palbociclib daily for 21 days followed by 7 days off in 28-day cycles, an aromatase inhibitor taken daily, and a GnRH agonist injected subcutaneously every 4 weeks. After completing first-line treatment, participants are randomized 28 days later into two groups for second-line treatment: one group receives oral talazoparib once daily plus intravenous atezolizumab every 28 days, while the other group receives only talazoparib daily. The treatments are given according to local guidelines and continue as per protocol. Participants will undergo assessments for disease progression and survival, with monitoring of laboratory tests and clinical status throughout the study. Researchers will collect tumor tissue and blood samples for biomarker analysis. Safety is monitored by evaluating adverse events and organ function. The primary outcome is the time until disease progression or death during second-line treatment, followed for up to 72 months. Participants must provide informed consent and agree to contraception and study procedures during their involvement.

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