A phase II trial of olaparib and durvalumab in metastatic BRCA wild type triple-negative breast cancer.

Abstract

TPS1111 Background: There is an urgent need to develop novel non chemotherapy treatments for metastatic triple negative breast cancer (mTNBC) patients who otherwise have a poor prognosis. Immune checkpoint blockade (ICB) and PARP inhibitors (PARPi) have independently shown promise for the treatment of mTNBC, and the combination has shown early benefit in the MEDIOLA and TOPACIO trials. This trial looks to 1) evaluate the efficacy of the combination of the PARPi olaparib and the PD-L1 inhibitor durvalumab, and 2) perform extensive multi-omics including protein based image analytics (multiplex IHC, cyclic immunofluorescence) on serial biopsies to identify predictive biomarkers and resistance mechanisms. Methods: Trial Design: This is a single-arm phase II study to assess the efficacy of the combination of olaparib and durvalumab in BRCA-wildtype mTNBC. mTNBC participants will undergo a pre-treatment biopsy, then will start a 4 week induction treatment with olaparib (300 mg PO BID). At the end of 4 weeks of single agent therapy, participants will undergo a repeat on-treatment biopsy, following which durvalumab (1500 mg IV every 4 weeks) will be added to olaparib. Participants will also be offered an optional biopsy on progression. Endpoints: The primary endpoint of this study is overall response rate (ORR) to olaparib and durvalumab therapy. Secondary efficacy endpoints include clinical benefit rate, duration of response, progression-free, and overall survival. The incidence and severity of on-treatment adverse events will be collected per CTCAE 5.0. Statistical Methods: 28 participants are planned for enrollment to this study. A 2-stage analysis will be performed using a Simon 2-stage Minimax design. The null (ICB alone) and alternative (ICB + PARPi) hypotheses are: H0: π = 0.15 and Ha: π = 0.35. For the primary endpoint, a total sample size of 28 participants will achieve 80% power to detect the ORR difference of 0.20 with one-sided type I error =0.05. The trial will be terminated in stage I if 2 or less out of the first 15 participants respond. If the trial goes on to the stage II, a total of 28 participants will be studied. If the total number responding is less than or equal to 7, the combination is rejected. Current Enrollment: The study was activated on 1/7/2019. To date, 3 out of 15 patients have been accrued to stage I of the study Clinical trial information: NCT03801369.