Data from Phase II DORA Study of Olaparib with or without Durvalumab as a Chemotherapy-Free Maintenance Strategy in Platinum-Pretreated Advanced Triple-Negative Breast Cancer

AbstractPurpose:We explored the efficacy of PARP inhibition with or without programmed death ligand-1 (PD-L1) blockade as chemotherapy-free maintenance therapy for advanced triple-negative breast cancer (aTNBC) sensitive to platinum-based chemotherapy.Patients and Methods:In the phase II non-comparative DORA trial (NCT03167619), patients with ongoing stable disease (SD) or complete/partial response (CR/PR) to first- or second-line platinum-based chemotherapy for TNBC (≤10% estrogen/progesterone receptor expression) were randomized 1:1 to receive olaparib 300 mg twice daily with or without durvalumab 1,500 mg on day 1 every 4 weeks. The primary objective was to compare progression-free survival (PFS) versus a historical control of continued platinum-based therapy.Results:45 patients were randomized (23 to olaparib alone, 22 to the combination; 3 with estrogen/progesterone receptor expression 1%–10%). At 9.8 months’ median follow-up, median PFS from randomization was 4.0 95% confidence interval (CI), 2.6–6.1 months with olaparib and 6.1 (95% CI, 3.7–10.1) months with the combination, both significantly longer than the historical control (P = 0.0023 and P BRCA mutation or PD-L1 status, but tended to be associated with CR/PR to prior platinum, particularly in the olaparib-alone arm. No new safety signals were reported.Conclusions:PFS was longer than expected with both regimens. A patient subset with wild-type BRCA platinum-sensitive aTNBC had durable disease control with chemotherapy-free maintenance.