Abstract GS3-02: Durvalumab compared to maintenance chemotherapy in patients with metastatic breast cancer: Results from phase II randomized trial SAFIR02-IMMUNO

Background : While treatment with anti-PDL1 improves outcome in combination with chemotherapy in patients with metastatic triple negative breast cancer, its efficacy is not explored yet in the context of maintenance therapy after chemotherapy, in a population of Her2-negative metastatic breast cancer. Methods : In SAFIR02 trial (NCT : 02299999), patients are selected to present a Her2-negative metastatic breast cancer eligible to 1st or 2nd line chemotherapy. All patients underwent a biopsy of metastatic disease, followed by targeted sequencing and Oncoscan when u003e30% cancer cells are present on HES slides. After 6 to 8 cycles of induction chemotherapy, patients who present an actionable genomic alteration are randomized between targeted therapies and continuation of maintenance chemotherapy, and patients without actionable alterations are randomized between durvalumab (dose, schedule) for 2 years and maintenance chemotherapy. As a substudy of the SAFIR02-breast trial, the SAFIR02-IMMUNO trial has its primary endpoint, the PFS, hierarchized as the primary end-point of the core of the study. The plan was to include 190 patients in order to have 80% power using a two-sided logrank test at the 5 % level of significance to detect an improvement from 3 months to 4.76 months corresponding to an HR of 0.63. Results : 191 patients have been randomized between durvalumab and maintenance chemotherapy (190 women) until now, 45.5% TNBC and 53.4% RH+. The median age was 55 years. . 91.6% (175/191) patients were randomized on their first line of chemotherapy in metastatic setting. Median number of metastatic sites at the beginning of the chemotherapy line was 2. PDL1 staining was performed on 89 available tumor FFPE blocks using SP142 antibody. 30% (n=27/89) patients presented a PDL1 positive tumor. PFS and OS will be presented at the conference.Conclusion : This is the first randomized trial comparing aPDL1 inhibitor to chemotherapy in the maintenance setting and to address the question of the efficacy of aPDL1i in HR+/Her2- and triple negative breast cancers. Citation Format: Florence Dalenc, Ingrid Garberis, Thomas Filleron, Amelie Lusque, Thomas Bachelot, Monica Arnedos, Mario Campone, Marie-Paule Sablin, Herve Bonnefoi, Marta Jimenez, Jacquet Alexandra, Fabrice Andre. Durvalumab compared to maintenance chemotherapy in patients with metastatic breast cancer: Results from phase II randomized trial SAFIR02-IMMUNO [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS3-02.