A case of metastatic dysgerminoma treated with two cycles neoadjuvant chemotherapy followed by fertility-sparing minimally invasive surgery

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Neoadjuvant chemotherapy (NACT) followed by fertility-sparing surgery is a feasible treatment of metastatic dysgerminoma

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As few as two cycles of NACT may result in enough of a tumor response for fertility-sparing surgery to be possible.

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Tumor lysis syndrome is a possibility when administering chemotherapy to patients with metastatic dysgerminoma

NCCN Guidelines Insights: Genetic/Familial High-Risk Assessment: Breast and Ovarian, Version 2.2017

The NCCN Clinical Practice Guidelines in Oncology for Genetic/Familial High-Risk Assessment: Breast and Ovarian provide recommendations for genetic testing and counseling for hereditary cancer syndromes and risk management recommendations for patients who are diagnosed with a syndrome. Guidelines focus on syndromes associated with an increased risk of breast and/or ovarian cancer. The NCCN Genetic/Familial High-Risk Assessment: Breast and Ovarian panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. The NCCN Guidelines Insights summarize the panel's discussion and most recent recommendations regarding risk management for carriers of moderately penetrant genetic mutations associated with breast and/or ovarian cancer.

Abstract LB-329: MicroRNA profiling to identify novel determinants of platinum resistance in BRCA1/2-mutated high-grade serous ovarian cancer

Ovarian cancer is the fifth leading cause of mortality in women and the most lethal of all gynecologic tumors. Patients with high grade serous ovarian carcinoma (HGSOC) have poor prognosis due to a combination of factors including lack of early detection and failure of therapeutic regimens. Approximately 50% of all ovarian tumors have germline/somatic mutations or epigenetic alterations in genes making up the homologous recombination (HR) pathway. The resultant “BRCAness” phenotype pre-disposes these tumors to an improved response from current ovarian cancer therapies i.e. platinum therapy and PARP inhibitors. Despite the predicted synthetic lethality, a majority of patients with recurrent ovarian cancer eventually develop resistance. A detailed understanding of clinically relevant mechanisms of chemotherapy resistance is an important step in improving disease outcomes.

To systematically identify microRNA (miRNA) mediators of chemo-resistance in HGSOC, we performed small RNA sequencing of 38 BRCA mutated tumors with known response to platinum chemotherapy and identified three miRNA’s: miR-139-5p, miR-493-5p and miR-494-3p that were significantly overexpressed in platinum resistant compared to the platinum sensitive tumors. Overexpression of these candidate miRNA’s was associated with worse overall outcome among BRCA1/2-mutated tumors in the TCGA dataset. Interestingly, overexpression of miR-493-5p only correlated with poor progression free survival in BRCA2 mutant tumors and not BRCA1 mutant tumors. Importantly, overexpression of miR-493-5p was also identified in 13 out of 40 olaparib resistant tumors in KB2P BRCA2 deficient mouse models. Additionally, overexpression of miR-493-5p in BRCA2 mutated HGSOC cell-lines induced resistance to cisplatin and olaparib in vitro. Mechanistically, resistance mediated by miR-493-5p was not associated with restoration of HR (as evaluated by restoration of Rad51 foci) but was rather related to replication fork stabilization. Identification of specific targets of miR-493-5p is currently underway. In summary, overexpression of miR-493-5p may be a novel mechanism of resistance to platinum and PARP-inhibitors in BRCA2-mutated ovarian cancers and may serve as a biomarker of response to these agents in BRCA2 mutated ovarian tumors. Inhibition of miR-493-5p may be a novel strategy to resensitize chemo-resistant BRCA2 mutated tumors to platinum therapy and PARP-inhibitors.

Citation Format: Khyati Meghani, Ewa Gogola, Sven Rottenberg, Jos Jonkers, Ursula Matulonis, Elizabeth Swisher, Panagiotis Konstantinopoulos, Dipanjan Chowdhury. MicroRNA profiling to identify novel determinants of platinum resistance in BRCA1/2-mutated high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-329. doi:10.1158/1538-7445.AM2017-LB-329

Abstract AP28: BRCA1 and RAD51C Promoter Hypermethylation Confer Sensitivity to PARP Inhibitors in Patients with Platinum Sensitive Ovarian Carcinoma

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.

Abstract DPOC-004: MAGENTA: MAking GENetic Testing more Accessible

The standard paradigm for cancer susceptibility genetic testing has been for patients to 1) be identified by their provider as being at high risk due to extensive family history or another diagnosis (e.g., breast cancer for ovarian risk testing), and 2) attend in–person pre and post– genetic test sessions with a genetic counselor to prepare for testing and learn about the results. This arrangement places boundaries around the types of women willing to spend this time and effort receiving testing, as providers are required to act as gatekeepers to the testing process. More open methods of accessing genetic testing and providing support need to be evaluated.

We propose to deliver personal, risk–based genetic testing and results to women from the general public using the Internet. Internet–based services offer several advantages over either in–person or telephone interventions. First, information can be accessed by participants and providers on their own schedules, at any location with internet access, and can be consumed at the pace and style that is best for individual tastes and styles. If necessary, information and support can be re–reviewed if the patient does not remember the initial counseling session. Second, delivery of information through the internet can be performed in a more efficient and cost–effective manner, reserving the limited in–person genetic counseling for individuals who need it the most, while providing support to the general public about basic medical and risk–based information. Recruitment via social media outlets can directly link potential participants to the Internet systems that screen for eligibility and provide testing support. Finally, Internet delivery can bring genetic testing to the patient in their home, eliminating a major barrier to testing (multiple visits to the provider)

The main objective of MAGENTA is to test the effects of on–line genetic education versus telephone genetic counseling on cancer distress and other psychological outcomes. We will recruit women using social media and other eHealth methods to participate in a randomized trial of ovarian cancer counseling and testing that is conducted online and using the telephone. We will conduct a (2x2 factorial design) randomized trial to test online versus telephone pre– and post–test genetic counseling for ovarian cancer risk among women at higher than average risk for ovarian cancer. We expect to enroll 3000 women through our media contacts to participate in MAGENTA. For genetic risk assessment, we will evaluate and provide feedback on 19 breast and ovarian cancer (OC) genes that have a clear relationship to cancer risk in collaboration with Color Genomics. Variants include ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM, MSH2, MSH6, MLH1, NBN, PALB2, PMS2, PTEN, RAD51C, RAD51D, TP53, and STK1. We will follow women for main psychological outcomes at 3 months post testing and longer for other outcomes.

Citation Format: Swisher E., Lu K., Bowen DJ, Gavin K. MAGENTA: MAking GENetic Testing more Accessible [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 DPOC-004.

Abstract AP27: FEASIBILITY OF MONITORING RESPONSE TO THE PARP INHIBITOR RUCAPARIB WITH TARGETED DEEP SEQUENCING OF CIRCULATING TUMOR DNA (CTDNA) IN WOMEN WITH HIGH GRADE OVARIAN CARCINOMA ON THE ARIEL2 TRIAL

BACKGROUND: TP53 mutations are present in >97% cases of high-grade serous ovarian cancer (HGSOC). Detection of TP53 mutations in ctDNA extracted from plasma has the potential to monitor disease course and treatment response. We have developed targeted amplicon deep sequencing (TADS) to detect low frequency mutations throughout the TP53 gene in ctDNA. Rucaparib is a PARP inhibitor in development for treatment of tumors with HR pathway deficiency. We used TADS to assess TP53 mutant allele fraction (MAF) in ctDNA from patients in ARIEL2, a phase 2 study of rucaparib for treatment of relapsed high-grade ovarian cancer (NCT01891344).

MATERIAL AND METHODS: Plasma samples (n=65) from 18 patients were collected during screening, on day 1 of each cycle, and at the end of rucaparib treatment. DNA extracted from plasma underwent TADS of TP53 (median depth 6916×). FFPE tumor specimens were profiled using an NGS-based assay with a targeted gene panel including TP53. Investigator-assessed clinical response rates were evaluated by RECIST v1.1 and GCIG CA-125 criteria.

RESULTS: Concordant TP53 mutations were detected in tumor and ctDNA from plasma for all 18 patients. Median TP53 MAF at screening and cycle 1 day 1 was 5.1% (interquartile range: 1.1–17.5, n=16) and 3.8% (IQR: 0.68–10.3, n=16), respectively. Fourteen patients were evaluable for response measured by quantification of TP53 MAF between cycle 1 and 2 (missing sample: n=2; TP53 MAF <0.5%; n=2). 7/9 patients with >50% reduction of TP53 MAF in ctDNA at cycle 2 achieved a RECIST confirmed PR (see Table); this included 5/6 patients with either a germline or somatic mutation in BRCA1/BRCA2. No patients with <50% reduction at cycle 2 (n=5) achieved a RECIST response.

CONCLUSIONS: Noninvasive detection of TP53 mutations by TADS is feasible, using plasma samples collected from women with relapsed platinum-sensitive high-grade ovarian cancer participating in an international multicenter trial. Circulating tumor DNA is a promising biomarker for monitoring response to the PARP inhibitor rucaparib. We are now testing the pre-specified hypothesis that a >50% reduction in TP53 MAF between baseline and cycle 2 is predictive of response to rucaparib using 560 plasma samples from 139 ARIEL2 subjects. Updated results will be presented at the meeting.

Citation Format: Anna Piskorz, Kevin K. Lin, James Morris, Elaina Mann, Amit Oza, Robert L. Coleman, David M. O'Malley, Michael Friedlander, Janiel M. Cragun, Ling Ma, Heidi Giordano, Nitzan Rosenfeld, Mitch Raponi, Iain A. McNeish, Elizabeth Swisher, James D. Brenton. FEASIBILITY OF MONITORING RESPONSE TO THE PARP INHIBITOR RUCAPARIB WITH TARGETED DEEP SEQUENCING OF CIRCULATING TUMOR DNA (CTDNA) IN WOMEN WITH HIGH GRADE OVARIAN CARCINOMA ON THE ARIEL2 TRIAL [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 AP27.

ARIEL4: An international, multicenter randomized phase 3 study of the PARP inhibitor rucaparib vs chemotherapy in germline or somatic BRCA1- or BRCA2-mutated, relapsed, high-grade ovarian carcinoma

TPS5603

Background: In high-grade epithelial ovarian carcinoma (OC), ≈18% of patients (pts) have tumors with a germline BRCA1 or BRCA2 mutation; ≈7% have tumors with a somatic BRCA1 or BRCA2 mutation (Pennington et al. Clin Cancer Res. 2014;20:764-75). The poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib is approved in the United States for treatment of pts with OC associated with a deleterious BRCA1 or BRCA2 mutation (germline and/or somatic) who have received ≥2 chemotherapies. Although PARP inhibitors have demonstrated clinical activity in OC in both treatment and maintenance settings, comparison to standard of care (SOC) has only been evaluated in the maintenance setting. Randomized studies are needed to assess the benefit-risk profile of PARP inhibitors vs current SOC as treatment for BRCA1- or BRCA2-mutated, relapsed, high-grade OC. Methods: ARIEL4 (NCT02855944) is evaluating rucaparib vs chemotherapy as treatment for pts with germline or somatic BRCA1- or BRCA2-mutated, relapsed, high-grade OC (regardless of histology) who have received ≥2 prior chemotherapy regimens. Approximately 345 pts will be randomized 2:1 to receive rucaparib (600 mg BID) (n = 230) or chemotherapy (n = 115) and stratified by progression-free interval after their most recent platinum regimen. Pts with platinum-resistant (progressive disease [PD] 1– < 6 mo after last platinum) or partially platinum-sensitive disease (PD 6– < 12 mo after last platinum) will be randomized to rucaparib or weekly paclitaxel; pts with platinum-sensitive disease (PD ≥12 mo after last platinum) will be randomized to rucaparib or platinum-based therapy (single-agent or doublet at the discretion of the investigator). Pts receiving chemotherapy have the option to cross over to rucaparib upon radiographic disease progression. The primary endpoint is progression-free survival. Secondary endpoints include investigator-assessed objective response rate (ORR) (RECIST version 1.1), ORR/CA-125 response, duration of response, overall survival, and pt-reported outcomes. Safety will be summarized descriptively using standard adverse event reporting. Clinical trial information: NCT02855944.

Small cell ovarian carcinoma: Long term survival in juvenile case with poor prognostic features

Background

Ovarian small cell carcinoma is a rare, aggressive neoplasm that occurs in young women and has a poor long-term prognosis. Treatment involves surgical resection and chemotherapy. The required radicality of surgery is uncertain, balancing cytoreduction with fertility preservation. Various chemotherapy regimens are utilized due to confusion regarding the neoplasm's lineage.

Case

We describe an adolescent with small cell carcinoma, hypercalcemic type, stage IA. Surgery included left salpingo-oopherectomy, left pelvic/paraaortic lymphadenectomy, omentectomy and peritoneal biopsies. She received four cycles of bleomycin, etoposide and cisplatin, similar to high-risk germ cell cancers. She has received no further therapy and is eleven years from diagnosis without evidence of disease.

Conclusion

This is the first long-term juvenile survivor managed with both fertility-sparing surgery and BEP (bleomycin, etoposide, cisplatin).

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SCCO can be treated with less-toxic chemotherapy directed at germ cell tumors.

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Fertility-sparing surgery should be considered in adolescents with early stage SCCO.

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Long term survival in adolescents with SCCO is possible.

Genetic/Familial High-Risk Assessment: Breast and Ovarian, Version 2.2015

The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast and Ovarian provide recommendations for genetic testing and counseling and risk assessment and management for hereditary cancer syndromes. Guidelines focus on syndromes associated with an increased risk of breast and/or ovarian cancer and are intended to assist with clinical and shared decision-making. These NCCN Guidelines Insights summarize major discussion points of the 2015 NCCN Genetic/Familial High-Risk Assessment: Breast and Ovarian panel meeting. Major discussion topics this year included multigene testing, risk management recommendations for less common genetic mutations, and salpingectomy for ovarian cancer risk reduction. The panel also discussed revisions to genetic testing criteria that take into account ovarian cancer histology and personal history of pancreatic cancer.

Phase I Study of Veliparib (ABT-888) Combined with Cisplatin and Vinorelbine in Advanced Triple-Negative Breast Cancer and/or BRCA Mutation-Associated Breast Cancer

PURPOSE

Cisplatin is synergistic with vinorelbine and the PARP inhibitor veliparib, and has antineoplastic activity in triple-negative breast cancer (TNBC) and BRCA mutation-associated breast cancer. This phase I study assessed veliparib with cisplatin and vinorelbine.

EXPERIMENTAL DESIGN

A 3+3 dose-escalation design evaluated veliparib administered twice daily for 14 days with cisplatin (75 mg/m(2) day 1) and vinorelbine (25 mg/m(2) days 1, 8) every 21 days, for 6 to 10 cycles, followed by veliparib monotherapy. Pharmacokinetics, measurement of poly(ADP-ribose) in peripheral blood mononuclear cells, and preliminary efficacy were assessed. IHC and gene-expression profiling were evaluated as potential predictors of response.

RESULTS

Forty-five patients enrolled in nine dose cohorts plus five in an expansion cohort at the highest dose level and recommended phase II dose, 300 mg twice daily. The MTD of veliparib was not reached. Neutropenia (36%), anemia (30%), and thrombocytopenia (12%) were the most common grade 3/4 adverse events. Best overall response for 48 patients was radiologic response with 9-week confirmation for 17 (35%; 2 complete, 15 partial), and stable disease for 21 (44%). Germline BRCA mutation presence versus absence was associated with 6-month progression-free survival [PFS; 10 of 14 (71%) vs. 8 of 27 (30%), mid-P = 0.01]. Median PFS for all 50 patients was 5.5 months (95% confidence interval, 4.1-6.7).

CONCLUSIONS

Veliparib at 300 mg twice daily combined with cisplatin and vinorelbine is well tolerated with encouraging response rates. A phase II randomized trial is planned to assess veliparib's contribution to cisplatin chemotherapy in metastatic TNBC and BRCA mutation-associated breast cancer. Clin Cancer Res; 22(12); 2855-64. ©2016 AACR.

Abstract A11: NGS-based tumor genomic profiling to identify ovarian cancer patients who benefit from the PARP inhibitor rucaparib

Background: PARP inhibitors (PARPi) are synthetically lethal to tumor cells with homologous recombination deficiency (HRD). HRD can result from deleterious BRCA1/2 mutations (BRCAmut) or other mechanisms that have not been fully elucidated. Regardless of mechanism, HRD leads to a common phenotype of genome-wide loss of heterozygosity (LOH). It has been hypothesized that this genomic phenotype can be used to identify BRCA wild-type (BRCAwt) HRD tumors likely sensitive to PARPi. Using comprehensive next generation sequencing (NGS)-based tumor genomic profiling, we developed an HRD assay for potential use as a companion diagnostic for rucaparib in high-grade ovarian cancer (HGOC) by combining tumor BRCA1/2 status and quantification of genomic LOH.

Methods: In the phase 2 study ARIEL2 Part 1 (NCT01891344), pre-treatment screening biopsies and archival formalin-fixed paraffin embedded tumor specimens were profiled using Foundation Medicine's NGS-based HRD assay, which detects all classes of genomic alterations, including base substitutions, insertions/deletions, and homozygous deletions in BRCA1/2. Genomic LOH was assessed by sequencing &gt;3,500 evenly-distributed single nucleotide polymorphisms across the genome and quantifying the extent of genomic LOH. A pre-specified genomic LOH cutoff was determined using publicly available SNP array data of ovarian tumors to predict platinum sensitivity as a surrogate marker for PARPi sensitivity. Response was assessed by RECIST v1.1 and GCIG CA-125 response criteria.

Results: As of July 1 2015, 195 archival tumor and 152 screening biopsy samples (142 matched pairs) from 206 HGOC patients enrolled (204 patients treated) in ARIEL2 Part 1 were successfully profiled using the NGS-based HRD assay. Some screening biopsies were not suitable for successful NGS-based HRD assessment primarily because of insufficient tumor nuclei or inadequate tumor volume. Most matched pairs of archival and pre-trial screening samples exhibited similar genomic LOH profiles (r=0.86); however, 14% of screening samples had higher genomic LOH compared with archival samples collected more than one year earlier. All BRCA1/2 germline and somatic mutated tumors had high genomic LOH in the screening samples. Receiver operating characteristic analysis of genomic LOH showed utility in identifying RECIST/CA-125 responders to rucaparib (AUC=0.72, p&lt;1e-4), with slightly better predictive utility using screening samples compared to archival samples (AUC=0.72 vs 0.69). Using the pre-specified genomic LOH cutoff, high genomic LOH tumors were detected in 54% of evaluable BRCAwt patients; significantly different overall response rates were found in patients with high vs low genomic LOH tumors (48% vs 26%; chi-square p=0.0074).

Conclusions: We developed an NGS-based HRD assay that assesses tumor BRCA1/2 and genomic LOH to prospectively identify HGOC patients who may benefit from rucaparib treatment. The optimized NGS-based HRD assay will be prospectively tested in the ongoing portion of the phase 2 study (ARIEL2 Part 2, NCT01891344) and a phase 3 maintenance study (ARIEL3, NCT01968213) that will investigate rucaparib in HGOC.

Citation Format: Iain A. McNeish, Kevin K. Lin, James X. Sun, Sandra Goble, Amit Oza, Robert L. Coleman, Clare L. Scott, Gottfried Konecny, Anna V. Tinker, David M. O'Malley, Rebecca Kristeleit, Ling Ma, James D. Brenton, Katherine Bell-McGuinn, Ana Oaknin, Alexandra Leary, Elaina Mann, Heidi Giordano, Roman Yelensky, Mitch Raponi, Elizabeth Swisher. NGS-based tumor genomic profiling to identify ovarian cancer patients who benefit from the PARP inhibitor rucaparib. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A11.

Abstract AS09: Germline mutations in cancer susceptibility genes in BRCA1 and BRCA2 negative families with ovarian and breast cancer

Objectives: Germline mutations in cancer susceptibility genes other than BRCA1 and BRCA2 (BRCA1/2) are found in approximately 6% of women with ovarian, fallopian tube, or primary peritoneal cancer. Our objective was to sequence BRCA1/2-negative ovarian cancer patients with a family history of ovarian or breast cancer to identify inherited mutations that may explain the familial risk.

Methods: We used a targeted capture, massively parallel sequencing test called BROCA on ovarian cancer probands with a family history of ovarian or breast cancer, or a personal history of breast cancer. BROCA testing included all known breast and ovarian cancer genes. Only clear loss of function mutations were included. 118 probands were ascertained from a gynecologic oncology tissue bank or outside referrals and provided informed consent. A family history of ovarian cancer was defined as having a first or second degree relative with ovarian cancer. A family history of breast cancer was defined as having a first or second degree relative with pre-menopausal breast cancer, or 2 or more regardless of menopausal status. Subjects were only included in one category.

Results: Of 118 ovarian cancer probands, 22 (18.6%) were found to carry deleterious mutations in non-BRCA1/2 cancer susceptibility genes. 8/29 (27.6%) ovarian cancer patients with a personal history of breast cancer had mutations in 7 genes (2 CHEK2, 2 RAD51D, 1 BRIP1, 1 TP53, 1 ATM, and one with both PALB2 and PMS2). This included mutations found in 2/5 (40%) who also had a family history of ovarian cancer and 4/10 (40%) who also had a family history of breast cancer. 38 patients had a family history of ovarian cancer with no personal history of breast cancer; 9/38 (23.7%) had mutations in 5 genes (3 BRIP1, 3 RAD51C, 1 RAD51D, 1 TP53, and 1 ATM). Finally, 5/51 (9.8%) ovarian cancer patients with a family history of breast cancer and no personal history of breast cancer had mutations in 5 genes (1 MSH6, 1 FAM175A, 1 NBN, 1 PALB2, and 1 CHEK2).

Conclusions: Germline mutations in DNA-repair genes are present in a substantial fraction of BRCA1/2-negative ovarian cancer patients with a personal or family history suggestive of inherited disease. These women may benefit from multiplex gene testing. The detection of inherited mutations in these women may be useful to identify the risk of other cancers, to inform family members of possible risk, and to direct therapy by suggesting candidates for PARP inhibitor therapy.

Citation Format: B. Norquist, M. Harrell, T. Walsh, J. Mandell, S. Bernards, K. Agnew, M. Lee, K. Pennington, M.C. King, E. Swisher. Germline mutations in cancer susceptibility genes in BRCA1 and BRCA2 negative families with ovarian and breast cancer [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS09.

Abstract 5467: BRCA1 N-terminal-deficient proteins provide PARP inhibitor and platinum resistance

Introduction: Tumors harboring BRCA1 mutations initially respond well to platinum and PARP inhibitor therapy; however, resistance invariably arises and is a major clinical problem. The BRCA1 185delAG allele is a common founder mutation located close to the protein translation start site, thought to produce a short peptide devoid of function.

Experimental procedures: In this study, we utilized the SUM1315MO2 breast cancer cell line that harbors a BRCA1 185delAG mutation to study mechanisms of PARP inhibitor and platinum resistance. SUM1315MO2 cells were cultured in the presence of increasing concentrations of the PARP inhibitor rucaparib or cisplatin until rucaparib resistant (RR) and cisplatin resistant (CR) clones emerged.

Results: DNA sequencing revealed that no BRCA1 gene reversion mutations were present in resistant cells. We next measured BRCA1 protein levels by Western blotting with antibodies specific for the N- and C-terminal domains of BRCA1. As a control, the wild-type BRCA1 protein expressed in MDA-MB-231 cells was detectable with both N- and C-terminal antibodies. In contrast, BRCA1 protein was undetectable in both SUM1315MO2 parental and resistant clones using the N-terminal specific antibody. However, the C-terminal specific antibody identified a more quickly migrating band of low abundance in parental cells, but with elevated expression in both RR and CR clones. We inferred that this protein was devoid of the extreme N-terminal RING domain-containing region that mediates interaction with BARD1. To investigate the functionality of the N-terminal truncated BRCA1 protein (Nt-BRCA1), we measured BRCA1 and RAD51 irradiation-induced focus formation by immunofluorescence. RR and CR clones demonstrated 2.25 - 2.75-fold increase (P = 0.024) in the number of cells with BRCA1 foci compared to parental cells. Similarly, we detected a 2 - 2.85-fold increase (P = 0.0325) in RAD51 foci formation in resistant clones compared to parental cells. Additionally, BRCA1 siRNA treated cells were 12- and 9-fold more sensitive to rucaparib compared to scrambled siRNA-treated control cells (P = 0.0002). Similarly, CR-1 cells treated with BRCA1 siRNAs were 1.56- and 1.7-fold more sensitive to cisplatin (P = 0.0346) compared to scrambled siRNA treated cells. Furthermore, N-terminal truncated BRCA1 proteins were detectable in a primary tumor from a germline BRCA1185delAG mutation carrier.

Conclusions: Taken together, these results provide evidence for a novel, mutation location-dependent mechanism of PARP inhibitor and platinum resistance.

Citation Format: Yifan Wang, Andrea Bernhardy, Emmanuelle Nicolas, Ryan Winters, Kathy Cai, Kelly Duncan, James Duncan, Maria Harrell, Elizabeth Swisher, Neil Johnson. BRCA1 N-terminal-deficient proteins provide PARP inhibitor and platinum resistance. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5467. doi:10.1158/1538-7445.AM2015-5467

Abstract 4670: A novel companion diagnostic predicts response to the PARP inhibitor rucaparib in ovarian cancer

Background: Genomic studies suggest that ∼50% of high-grade serous ovarian cancers (OC) have homologous recombination deficiency (HRD). Germline BRCA1/2 mutations (gBRCAmut) are expected to account for 1/3 of HRD in OC, and identification of non-gBRCAmut HRD tumors likely to respond to PARP inhibitors (PARPi) remains a challenge. Using comprehensive next generation sequencing (NGS)-based tumor genomic profiling, we developed a companion diagnostic HRD assay to predict sensitivity to the PARP inhibitor rucaparib by combining tumor BRCA1/2 status (germline and somatic) and genomic loss of heterozygosity (LOH). The HRD assay is being validated in a Phase 2 study (ARIEL2) and will be prospectively applied to the primary analysis of the ongoing Phase 3 study (ARIEL3) of rucaparib.

Methods: The HRD assay uses 50-200ng of DNA from tumor FFPE specimens, which undergoes sequencing library construction and hybrid-capture of all coding exons from 100s of cancer-related genes. Libraries are sequenced to high, uniform depth (&gt;500× unique coverage, Illumina® HiSeq) and data are processed by a customized pipeline that accurately detects all classes of genomic alterations, including BRCA1/2 base substitutions, indels, and homozygous deletions. Genomic LOH is assessed by a CGH-like analysis of sequencing coverage and &gt;3,500 genome-wide SNPs and a tumor is classified as HRD with either BRCA1/2 alteration or high genomic LOH (LOH+). Somatic/germline status of discovered BRCA1/2 alterations is assessed by a previously-presented computational approach (“SGZ”, AACR 2014 abstract #1893), and verified against medical records where available. ARIEL2 is an ongoing single-arm (n = 180), open-label study of rucaparib in recurrent, platinum-sensitive OC patients. The primary objective is to evaluate clinical activity of rucaparib among 3 prospectively defined subgroups: tumor BRCAmut, BRCAwt/LOH+ (“BRCAness”) and BRCAwt/LOH-. Response is determined by RECIST and/or GCIG-CA125 criteria.

Results: The HRD assay was performed on tumors from 121 patients, of whom 25% were found to be BRCA mutant (17 germline/12 somatic), 42% had the BRCAness signature (BRCAwt/LOH+), and 33% were biomarker negative (BRCAwt/LOH-). Efficacy data available for 61 patients revealed objective response rates (combined RECIST/CA125 criteria) at 70%, 40% and 8%, respectively. Responses were observed for all classes of genomic alterations, and in gBRCAmut and non-gBRCAmut tumors.

Conclusions: Preliminary clinical data indicates that the HRD assay identifies OC patients likely to respond to rucaparib and highlights the potential for innovative companion diagnostics enabled by comprehensive genomic profiling based on NGS.

Citation Format: James Sun, Iain McNeish, Robert L. Coleman, Amit Oza, Clare Scott, David M. O'Malley, Kevin K. Lin, Christine Burns, Christine Vietz, Philip J. Stephens, Murtaza Mehdi, Matthew Hawryluk, Heidi Giordano, Mitch Raponi, Lindsey Rolfe, Jeff Isaacson, Vincent A. Miller, Andrew Allen, Elizabeth Swisher, Roman Yelensky. A novel companion diagnostic predicts response to the PARP inhibitor rucaparib in ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4670. doi:10.1158/1538-7445.AM2015-4670