Homologous recombination deficiency (HRD) predicted most responses to the PARP inhibitor olaparib (Lynparza) in patients with triple-negative breast cancer (TNBC), including patients without germline (g)BRCA or PALB2 mutations, a small clinical trial showed.
Overall, 18 of 32 TNBCs responded to primary treatment with olaparib, and HRD was present in 16 of 18 responding tumors. A majority of responses occurred in tumors without germline mutations, in contrast to conventional wisdom about PARP inhibitors’ activity in breast cancer.
“Olaparib monotherapy yielded a high response rate when administered to treatment-naïve, large TNBC, with germline or somatic HR deficiency,” reported Hans Petter Eikesdal, MD, of the University of Bergen in Norway, and colleagues in the Annals of Oncology. “While the benefit of PARP inhibitor monotherapy in TNBC needs confirmation, it presents a potential sequential approach for TNBC downstaging prior to chemotherapy.”
PARP inhibitors’ have established antitumor activity in breast cancers