Oaknin, Ana

3 The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Sunday, June, 2, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Sunday edition of ASCO Daily News.

Abstract A key resistance mechanism to platinum-based chemotherapies and PARP inhibitors in BRCA-mutant cancers is the acquisition of BRCA reversion mutations that restore protein function. To estimate the prevalence of BRCA reversion mutations in high-grade ovarian carcinoma (HGOC), we performed targeted next-generation sequencing of circulating cell-free DNA (cfDNA) extracted from pretreatment and postprogression plasma in patients with deleterious germline or somatic BRCA mutations treated with the PARP inhibitor rucaparib. BRCA reversion mutations were identified in pretreatment cfDNA from 18% (2/11) of platinum-refractory and 13% (5/38) of platinum-resistant cancers, compared with 2% (1/48) of platinum-sensitive cancers (P = 0.049). Patients without BRCA reversion mutations detected in pretreatment cfDNA had significantly longer rucaparib progression-free survival than those with reversion mutations (median, 9.0 vs. 1.8 months; HR, 0.12; P < 0.0001). To study acquired resistance, we sequenced 78 postprogression cfDNA, identifying eight additional patients with BRCA reversion mutations not found in pretreatment cfDNA. Significance: BRCA reversion mutations are detected in cfDNA from platinum-resistant or platinum-refractory HGOC and are associated with decreased clinical benefit from rucaparib treatment. Sequencing of cfDNA can detect multiple BRCA reversion mutations, highlighting the ability to capture multiclonal heterogeneity. This article is highlighted in the In This Issue feature, p. 151

Abstract Germline and somatic mutations in BRCA1 and BRCA2 (BRCA) confer PARP inhibitor sensitivity. Promoter hypermethylation is an alternate mechanism of gene down-regulation, and BRCA1 promoter methylation is relatively common in sporadic ovarian cancer. The clinical significance of BRCA1 methylation is less clear than for mutations, as the Cancer Genome Atlas (TCGA) and others have failed to show improved survival in ovarian carcinomas with BRCA1 methylation. No one has previously tested whether BRCA1 methylation confers in vivo sensitivity to PARP inhibitors in patients with ovarian cancer. ARIEL2 is a phase 2 study of the PARP inhibitor rucaparib in patients with recurrent platinum sensitive high-grade ovarian, peritoneal or fallopian tube carcinoma. At enrollment, ARIEL2 required pre-treatment tumor biopsies with the goal of developing tissue predictors of PARP inhibitor sensitivity other than BRCA mutations. The number of women with known germline mutations was capped at 15 patients in order to predominantly enroll BRCA wildtype cases. As presented at ASCO 2016, in cases with no BRCA mutations, a high fraction of genomic loss of heterozygosity (LOH) significantly predicted a better progression-free survival (the primary endpoint), longer duration of response, and a higher fraction of responders compared to cases with low LOH. We assessed BRCA1 and RAD51C promoter hypermethylation using methylation-sensitive polymerase chain reaction in paired archival and pre-treatment biopsies from patients on ARIEL2. Of 165 cases for which methylation analyses were completed, 21 (12.7%) were methylated at the BRCA1 promoter and four (2.4%) at the RAD51C promoter. Methylation of BRCA1 and RAD51C was mutually exclusive with mutation in BRCA or other homologous recombination genes. All four cases with RAD51C methylation and 15/19 (78.9%) with BRCA1 methylation were associated with high LOH. In 90 paired samples archival and pre-treatment tissues, RAD51C methylation was 100% concordant and BRCA1 methylation was highly concordant (p<0·001). For 13 cases with BRCA1 methylation in the archival specimen, 4 (30·8%) were unmethylated in the paired pretreatment tumor, but for 77 unmethylated archival specimens, gain of methylation in the pretreatment biopsy was observed just once. Confirmed RECIST responses were seen in 52.4% (11/21) BRCA1 methylated and 75.0% (3/4) RAD51C methylated cases. In conclusion, BRCA1 and RAD51C methylation in ovarian carcinomas correlates with a high response rate to PARP inhibitors. If methylation was to be used as a predictor of PARP inhibitor sensitivity, it would need to be assessed in a pre-treatment (not archival) specimen. The loss of BRCA1 methylation in recurrent ovarian carcinoma, which was common even in these platinum sensitive cases, could explain why BRCA1 methylation is associated with similar survival to methylated cases, despite initial improved therapeutic sensitivity. Citation Format: Elizabeth Swisher, Maria Harrell, Kevin K. Lin, Clare Scott, Sandra Goble, Amit Oza, Robert L. Coleman, Gottfried Konecny, Anna V. Tinker, David M. O'Malley, Rebecca Kristeleit, Ling Ma, James Brenton, Katherine Bell-McGuinn, Ana Oaknin, Alexandra Leary, Elaina Mann, Heidi Giordano, Mitch Rapon, Iain McNeish, Scott H. Kaufmann. BRCA1 and RAD51C Promoter Hypermethylation Confer Sensitivity to PARP Inhibitors in Patients with Platinum Sensitive Ovarian Carcinoma [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP28.

3 Background: Vascular endothelial growth factor (VEGF) promotes angiogenesis, a mediator of disease progression in cervical cancer. Bevacizumab (B), a humanized anti-VEGF monoclonal antibody, has shown single-agent activity in pretreated recurrent disease. We aimed to evaluate B in chemotherapy (CTX)-naive recurrent/persistent/metastatic cervical cancer. Methods: Using a 2x2 factorial design, patients were randomly assigned to CTX with or without B 15 mg/kg. The CTX regimens included cisplatin 50 mg/m2 plus paclitaxel 135-175 mg/m2 and topotecan 0.75 mg/m2 d1-3 plus paclitaxel 175 mg/m2d1. Cycles were repeated every 21 days until disease progression, unacceptable toxicity, or complete response. Overall survival (OS) was the primary endpoint with a reduction in the hazard of death by 30% using anti-VEGF therapy considered important (90% power, 1-sided alpha=2.5%). Final analysis was planned when 346 deaths were observed. Results: 452 patients were accrued from 4/6/09 to 1/3/12. The scheduled interim analysis occurred after 174 patients had died and showed that the topotecan-paclitaxel backbone was not superior to the cisplatin-paclitaxel backbone. A second interim analysis was conducted after 271 deaths. A total of 225 patients received CTX alone and 227 patients received CTX plus B. The randomized treatment groups were similar with regard to age, histology, performance status, previous platinum as a radiosensitizer, and recurrence, persistence, or advanced disease. The B-to-no-B hazard ratio (HR) of death was 0.71 (97.6% CI 0.54-0.95; 1-sided p=0.0035). Median survival was 17 m (CTX plus B) and 13.3 m (CTX alone). The RR were 48% (CTX plus B) and 36% (CTX alone) (p=0.0078). Treatment with B was associated with more grade 3-4 bleeding (5 vs 1%) thrombosis/embolism (9 vs 2%), and GI fistula (3 vs 0%). Conclusions: For the first time a targeted agent significantly improved OS in gynecologic cancer. The second interim analysis crossed the boundary for efficacy, warranting early release of this information. The nearly 4-month increase in median OS with the addition of B to CTX in women with recurrent cervical cancer is considered to be clinically significant. Clinical trial information: NCT00803062.