Abstract CT562: PARTNER: Randomised, phase II/III trial to evaluate the safety and efficacy of the addition of Olaparib to Platinum-based neoadjuvant chemotherapy in triple negative and/or germline BRCA mutated breast cancer patients

Abstract

Background: Triple Negative Breast Cancers (TNBC) are a biologically diverse and aggressive subgroup lacking targeted therapy. TNBC and Germline BRCA (gBRCA) breast cancer share certain phenotypic and molecular similarities, with gBRCA mutations seen in 10% to 20% of TNBC patients. Homologous recombination deficient tumours, especially those caused by germline or somatic BRCA mutations, are thought to be particularly sensitive to PARP inhibitors. Aim: To establish if the addition of Olaparib to neoadjuvant Platinum-based chemotherapy in the treatment of basal TNBC and/or gBRCA breast cancer is safe and increases efficacy. Trial design: 3-stage open label randomised phase II/III trial of neoadjuvant Paclitaxel and Carboplatin +/- Olaparib, followed by clinicians' choice of Anthracycline regimen. Stages 1 and 2: Randomisation (1:1:1) to control (3-weekly carboplatin AUC5/weekly with paclitaxel 80mg/m2 for 4 cycles), or to one of two research arms. These use an identical chemotherapy regimen and also include different treatment schedules of Olaparib 150mg BD for 12 days. Stage 3: Randomisation (1:1) to either the control or research arm chosen following stage 2. End-points: Stage 1: Safety; Stage 2: Schedule selection based on pCR rate and Olaparib completion rate using a “pick-the-winner” design. Stage 3: pCR rate. This trial includes an optional pathway (PARTNERING) for patients with evidence of residual disease after six chemotherapy cycles. This aims to establish if the addition of new agents (ATR inhibitor and PD-L1 inhibitor) improves treatment response. Eligibility criteria: Aged 16-70; histologically confirmed invasive breast cancer; ER-negative, HER2-negative with TNBC basal phenotype or gBRCA positive, HER2-negative irrespective of hormone status; stage T1-4 N0-2; performance status 0-1; treatment within 6 weeks of diagnostic biopsy; biomarker scores: TILs, CK 5/6, EGFR +/- AR. Statistical methods: The recruitment of TNBC non-gBRCA and gBRCA patients is independent. Enrichment design is applied with an overall significance level 0.05(α) and 80% power. A minimum of 780 patients will be included to detect an absolute improvement of 15% (all patients and TNBC non-gBRCA cohort) and 20% (gBRCA patients) by combining Olaparib with Platinum based chemotherapy. A minimum of 478 TNBC non-gBRCA and 188 gBRCA patients will be recruited. Each PARTNERING cohort will consist of 15 patients. Current Enrollment: Since May 2016, 756 patients from 30 sites have been enrolled. Stages 1 and 2 are completed. An IDSMC review identified no safety concerns and Research Arm 2 was selected. This arm involves Olaparib administration on days 3-14. Stage 3 Phase I (recruitment of non-gBRCA and gBRCA patients) completed in December 2021. Stage 3 Phase II (recruitment of gBRCA patients only) remains open to patients to UK and internationally. 5 patients have been enrolled in PARTNERING. ClinicalTrials.gov Identifier: NCT03150576 Citation Format: Lynsey Drewett, Karen A. Pinilla, Louise Grybowicz, Jerome Wulff, Alimu Dayimu, Nikolaos Demiris, Rebecca Lucey, Anne-Laure Vallier, Wendi Qian, Andrea Machin, PARTNER Research Team, Karen McAdam, Rebecca Roylance, Ellen R. Copson, Anne Armstrong, Nicola Levitt, Elena Provenzano, Marc Tischkowitz, Emma McMurtry, Helena Earl, Jean E. Abraham. PARTNER: Randomised, phase II/III trial to evaluate the safety and efficacy of the addition of Olaparib to Platinum-based neoadjuvant chemotherapy in triple negative and/or germline BRCA mutated breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT562.