Phase I Study of the Oral PI3kinase Inhibitor BKM120 or BYL719 and the Oral PARP Inhibitor Olaparib in Patients With Recurrent Triple Negative Breast Cancer or High Grade Serous Ovarian Cancer

We analyzed massive parallel sequence data from patients with breast and ovarian cancer and identified single base substitution mutational signature 3 (Sig3) - extracted using SigMA - as a biomarker of homologous recombination deficiency (HRD) and predictive for response to PARP inhibitors. Participants were patients enrolled in clinical trials as 2 independent datasets: (1) high-grade serous ovarian cancer and triple-negative breast cancer (TNBC) from a Phase 1b trial of the PARP inhibitor olaparib in combination with the PI3K inhibitor buparlisib (BKM120) (NCT01623349), and (2) TNBC patients who received neoadjuvant olaparib in the Phase II PETREMAC trial (NCT02624973).