Abstract A074: Correlation of homologous recombination deficiency (HRD) status by BROCA-HR sequencing with response to combination cediranib and olaparib in relapsed ovarian cancer

Abstract

Abstract Background: The combination of cediranib (ced) and olaparib (olap) improves progression-free survival and overall response rates (ORR) in women with recurrent plat sensitive high-grade serous (HGS) ovarian cancer compared to olap alone. In this Phase 2 study of ced/olap in women with relapsed ovarian cancer (NCT02345265), we observed an ORR of 74% with ced/olap in plat sensitive relapsed patients (pts) and an ORR of 20% in plat resistant pts. BROCA-HR was performed to characterize tumor HRD status and to correlate this with the activity of ced/olap in the plat sensitive and resistant settings. Methods: Pts with relapsed ovarian cancer across 11 centers were enrolled to 2 cohorts, either plat sensitive or resistant. All pts received ced 30mg daily and olap tablets 200mg BID. Archival, pre-treatment, and on-treatment biopsies were collected on all pts where safely feasible; pts also had the option of undergoing a post-progression biopsy. A baseline blood sample was collected for germline testing and matched control. Available samples were sequenced with BROCA-HR, and HRD status was determined by (1) presence of an HR-related mutation or (2) an increase in loss of heterozygosity (LOH) score. Results: 72 pts were enrolled, with 70 pts receiving study treatment (35 plat sensitive and 35 plat resistant). BROCA-HR analysis is complete on 60 samples, with 10 samples in final analysis. The concordance of HRD status by presence of an HR-related mutation or by LOH score was relatively low (agreement=36/60=60%, Cohen's Kappa=0.28). In 19 pts with a germline BRCA mutation, 16 were HRD+ by LOH (LOH high), 2 were HRD- by LOH (LOH low), and 1 not quantifiable. 3 pts had a somatic BRCA mutation; 1 was LOH high, 1 LOH low, and 1 not quantifiable. 4 pts had non-BRCA somatic HR-related mutations (3 CDK12; 1 ATR); 3 were LOH high and 1 LOH low. Of the 34 pts without HR-related mutations, 15 were LOH high, 16 were LOH low, and 3 not quantifiable. In 29 plat sensitive pts with BROCA-HR results, 18 were HRD+ by mutation (12 germline BRCA, 3 somatic BRCA, 3 somatic other), and 16 were HRD+ by LOH (LOH high). The ORR in plat sensitive pts by HRD status with available HRD results was: 22/29=75.9% (13/18=72% HRDmut+; 9/11=82% HRDmut-); (12/16=75% LOH high; 6/9= 67% LOH low). In 31 plat resistant pts with BROCA-HR results, 8 were HRD+ by mutation (7 germline BRCA, 0 somatic BRCA, 1 somatic other), and 19 were HRD+ by LOH. The ORR in plat resistant pts by HRD status with available HRD results was: 7/31=22.6% (4/8=50% HRDmut+; 3/23=13% HRDmut-, P=0.05); (7/19=37% LOH high; 0/11= 0% LOH low, P=0.03). Updated results with the full data set are pending. Conclusion: Ced/olap has clinical activity in women with relapsed ovarian cancer, both in the plat sensitive and plat resistant settings. In women with plat sensitive disease, where response rates are high, HRD status by presence of an HR-related mutation or LOH status does not appear to provide significant additional information regarding likelihood of response. In women with plat resistant disease, the presence of HRD by an HR-related mutation or LOH status is correlated with a higher likelihood of response. Citation Format: Joyce F Liu, Su-Chun Cheng, Robert M Wenham, Andrea E Wahner Hendrickson, Deborah K Armstrong, Nancy Chan, David E Cohn, Jung-Min Lee, Richard T Penson, Mihaela Cristea, James Abbruzzese, Koji Matsuo, Alexander B Olawaiye, Jennifer Curtis, Geoffrey Shapiro, Ursula A Matulonis, Elise Kohn, Percy Ivy, Elizabeth M Swisher. Correlation of homologous recombination deficiency (HRD) status by BROCA-HR sequencing with response to combination cediranib and olaparib in relapsed ovarian cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A074. doi:10.1158/1535-7163.TARG-19-A074