FUnctional Selection of Advanced Breast Cancer Patients for Talazoparib Treatment Using the REpair Capacity (RECAP) Test

This is a single arm, prospective multicenter study among patients with advanced breast cancer with RECAP-based HRD phenotype who will be treated with talazoparib, a strong PARP inhibitor. After signing informed consent, metastatic breast cancer patients will undergo an ultrasound (or CT-) guided biopsy in order to obtain at least two biopsies from a metastatic lesion to determine the HR status by the RECAP test and a blood withdrawal for ctDNA isolation. HR proficient (HRP) patients will receive anti-tumor therapy (non study drug) on discretion of their treating physician; only the response on treatment will be registered. Approximately 30% of screened patients will have an HRD tumor and thus will be eligible to start talazoparib monotherapy until PD or unacceptable side effects. The primary endpoint is PFS at four months. Additional endpoints will include overall response rate and overall survival. Upon progression, patients will be kindly asked for consent to perform another biopsy (optional) and blood withdrawal in order to prove reversibility of the RECAP test outcome (from HRD to HRP) and explore potential mechanisms of resistance (both in tissue and ctDNA).