Wild-type BRCA1 Research Articles

Arthralgia in patients with ovarian cancer treated with bevacizumab and chemotherapy

BackgroundChemotherapy with carboplatin, paclitaxel, and bevacizumab is the standard therapy for patients with advanced stage ovarian cancer wild-type BRCA after primary surgery. The most frequent side effects of bevacizumab in...

Bevacizumab as maintenance treatment in BRCA mutated patients with advanced ovarian cancer: A large, retrospective, multicenter case-control study

ObjectiveThe aim of this study was to investigate the correlation between BRCA mutational status and response to bevacizumab in a large advanced ovarian cancer (AOC) series. MethodsThis is a multicenter, retrospective case-control study including upfront AOC treated between January 2015 and June 2019. The main inclusion criteria were: having received three weekly carboplatin-paclitaxel as first-line treatment, with or without Bevacizumab maintenance, knowledge of the BRCA mutational status. ResultsOverall, 441 patients were included; 183 (41.5%) patients received bevacizumab (Cases), and 258 (58.5%) did not receive it (Controls). The BRCA mutated patients (BRCAmut) were 58 (39%) in the Cases group and 90 (34.9%) in the Controls group (p = .77).Patients who received bevacizumab had a significant 4-months increase in median progression free survival (mPFS: 21 vs. 17 months, p = .033). Concerning BRCAmut patients, no differences were shown between those who received bevacizumab or not in terms of mPFS (24 vs. 22 months, p = .3). Conversely, in BRCA wild-type (BRCAwt) population bevacizumab administration significantly prolonged mPFS (20 vs 15 months, p = .019). At multivariate analysis, independent factors of prolonged PFS were BRCA status (OR = 0.60), having received PDS (OR = 0.69), and complete cytoreduction (OR = 0.50), but not the bevacizumab administration (OR = 0.83, p = .22). ConclusionsNo evidence of oncological benefit in terms of PFS and OS related to bevacizumab maintenance therapy was found in BRCAmut patients. Differently, BRCAwt patients seem to benefit from antiangiogenic treatment in terms of mPFS.

Resistance to the CHK1 inhibitor prexasertib involves functionally distinct CHK1 activities in BRCA wild-type ovarian cancer

High grade serous ovarian cancer (HGSOC) is a fatal gynecologic malignancy in the U.S. with limited treatment options. New therapeutic strategies include targeting of the cell cycle checkpoints, e.g., ATR and CHK1. We recently reported a promising clinical activity of the CHK1 inhibitor (CHK1i) prexasertib monotherapy in BRCA wild-type (BRCAwt) HGSOC patients. In this study, biopsies of treated patients and cell line models were used to investigate possible mechanisms of resistance to CHK1i. We report that BRCAwt HGSOC develops resistance to prexasertib monotherapy via a prolonged G2 delay induced by lower CDK1/CyclinB1 activity, thus preventing cells from mitotic catastrophe and cell death. On the other hand, we noted CHK1’s regulation on RAD51-mediated homologous recombination (HR) repair was not altered in CHK1i-resistant cells. Therefore, CHK1i sensitizes CHK1i-resistant cells to DNA damaging agents such as gemcitabine or hydroxyurea by inhibition of HR. In summary, our results demonstrate new mechanistic insights of functionally distinct CHK1 activities and highlight a potential combination treatment approach to overcome CHK1i resistance in BRCAwt HGSOC.

Abstract A05: Maintenance therapy for platinum-sensitive (PS) recurrent ovarian cancer (rOC): What are we actually choosing?

Abstract Background: Treatment for platinum-sensitive (PS) recurrent ovarian cancer (rOC) patients generally consists of retreatment with platinum-based chemotherapy. Maintenance therapy with a targeted agent can extend the interval before progression. Patients with a somatic or germline BRCA mutation (BRCAm) have a greater clinical benefit with maintenance PARPi compared to BRCA wild-type (BRCAwt). Data have shown that ~50% of patients eligible for maintenance therapy do not receive it and variation in the type of maintenance therapy prescribed (BEV vs. PARPi) exists both nationally and within institutions. The objective of this study was to analyze the utilization of maintenance therapy in PS rOC at a large, high-volume academic institution. Methods: This retrospective cohort study evaluated PS rOC patients seen at the University of Alabama at Birmingham (UAB) who completed 2nd line or greater platinum-based chemotherapy for 3-8 cycles since March 27, 2017 (date of FDA approval for PARPi maintenance). Medical records on all patients were reviewed from 9/2018-2/2019 to capture a recent representative sample. Percent of patients and what type of maintenance therapy they received after platinum-based treatment were assessed. The difference in BRCA status between these groups was evaluated. Progression-free survival (PFS) was compared between those who received maintenance therapy and those that did not. PFS was defined as the date of initiation of platinum-based chemotherapy until progression of disease or death regardless of whether or not they were on maintenance therapy (based on PFS definition in BEV maintenance phase III clinical trials). Results: There were 61 PS rOC patients seen during this time period who were eligible for maintenance therapy. 72% received maintenance therapy: 86% (n=38) received PARPi and 14% (n=6) received BEV. PFS following platinum-based chemotherapy with at least one dose of maintenance therapy was 13.4m (6.5-23.6) vs. 11.4m (7.5-27.0) with no maintenance therapy. Germline and somatic BRCA status were known in ~75% of the cases. 60% (9/15) of the patients with a BRCAm (somatic or germline) received maintenance therapy; all patients received a PARPi. PFS in these patients was 17.5m (15.6-19.0) vs. 10.7m (8.0-27.0) with no maintenance therapy. Conclusions: Consistent with randomized control trials, maintenance therapy prolonged PFS in PS rOC patients, which was more pronounced in BRCAm patients who received a PARPi, although not statistically significant in our small cohort of patients. At our institution, >50% of patients who were eligible for maintenance therapy received it, which is higher than data obtained from national databases. While 30% of the patients did not receive maintenance therapy, this could have been based on a multitude of factors including toxicity, degree of benefit, cost, etc. Only 60% of the patients with known BRCAm received maintenance PARPi, which warrants further investigation into the potential barriers that exist. Citation Format: Hannah Beer, Jaclyn Arquiette, Angelina I. Londono, Mckenzie Foxall, Charles A. Leath III, Rebecca C. Arend. Maintenance therapy for platinum-sensitive (PS) recurrent ovarian cancer (rOC): What are we actually choosing? [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A05.

Abstract PR01: Assessment of PARPi and cisplatin resistance in BRCA1 exon 11 mutant patient -derived xenografts

Abstract Introduction: The BRCA1 protein contributes to homologous recombination (HR) repair of DNA breaks. BRCA1 mutations often result in dysfunction or absence of BRCA1 proteins. Consequently, BRCA1 mutations induce PARP inhibitor (PARPi) and cisplatin sensitivity. BRCA1 exon 11 is the largest exon and harbors a plethora of germline mutations. BRCA1 exon 11 is subject to alternative splicing and can generate the BRCA1-Δ11q isoform. This isoform is a hypomorphic variant that removes germline exon 11 mutations allowing for translation through to the end of the protein. In this study we examined PARPi and cisplatin sensitivity and resistance in a panel of BRCA1 exon 11 mutant PDX tumors. Experimental Procedures: Wild-type BRCA1 PDX036, exon 13 truncating BRCA1 mutant PDX1126, and BRCA1 exon 11 mutants PDX017, PDX056, and PDX124 were utilized. Using these models, we developed several isogenic sets of cisplatin and PARPi sensitive/resistant PDX using serial passaging and treatments. Additionally, we developed a method for lentiviral manipulation of PDX models to study resistance mechanisms. We assessed tumors for cisplatin and PARPi sensitivity and examined BRCA1 and 53BP1 expression by Western blotting and immunohistochemistry. Results: We observed variable responses to cisplatin and PARPi treatments among PDX models despite the presence of BRCA1 mutations that abrogated expression of full-length BRCA1. PDX196 expressed an abundance of BRCA1-Δ11q and exhibited resistance to both PARPi and cisplatin treatments. Interestingly, exon 11 mutant PDX017, 056, and 124 initially responded to both cisplatin and PARPi treatments. Serial passaging and treatments ultimately elicited resistance in each of these models and in some tumors coincided with an increase in BRCA1-Δ11q expression. Additionally, PARPi and cisplatin-resistant PDX017 tumors exhibited a simultaneous reduction of 53BP1 and increased BRCA1-Δ11q expression. In contrast to the BRCA1 exon 11 mutant PDX models, exon 13 mutant PDX1126 failed to develop resistance after multiple rounds of serial passaging with either cisplatin or PARPi treatments. However, when PDX1126 cells were transduced with lentivirus containing BRCA1-Δ11q cDNA, a rapid acquisition of cisplatin resistance occurred. Conclusions: Our data indicate BRCA1-Δ11q expression is variable in BRCA1 exon 11 mutant tumors, but nevertheless, when abundantly expressed, supports resistance to cisplatin and PARPi. This abstract is also being presented as Poster A46. Citation Format: John J Krais, Emma Clausen, Vladimir Khazak, Igor Astsaturov, Clare L Scott, Neil Johnson. Assessment of PARPi and cisplatin resistance in BRCA1 exon 11 mutant patient -derived xenografts [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr PR01.

Prexasertib: an investigational checkpoint kinase inhibitor for the treatment of high-grade serous ovarian cancer

ABSTRACT Introduction Patients with high-grade serous ovarian cancer (HGSOC) have a poor prognosis, and current chemotherapy regimens for treating advanced disease are far from satisfactory. Prexasertib (LY2606368) is a novel checkpoint kinase inhibitor (CHK) under investigation for the treatment of HGSOC. Data from a recent phase II trial showed promising efficacy and safety results for treating wild-type BRCA HGSOC. Areas covered This article reviews the available data on the pharmacokinetics, pharmacodynamics, clinical efficacy, and safety of prexasertib in the treatment of HGSOC. Expert opinion Until now, prexasertib demonstrated clinical activity in phase I and II clinical trial for treating wild-type BRCA HGSOC, whereas its promising efficacy as monotherapy and combined with olaparib in BRCA-mutated HGSOC has been preliminary evidenced only in phase I studies. Compared to other drugs of the same class, prexasertib showed a better tolerability profile, causing moderate hematological toxicity. Further studies are needed to confirm efficacy and safety profiles of prexasertib in combined regimens. New early clinical trials may investigate prexasertib administered with programmed cell death ligand 1 (PD-L1) and PI3 K inhibitors due to the preclinical evidence of a synergic action.

Homozygous hypomorphic BRCA2 variant in primary ovarian insufficiency without cancer or Fanconi anaemia trait

BackgroundPrimary ovarian insufficiency (POI) affects 1% of women under 40 years and is a public health problem. The genetic causes of POI are highly heterogeneous with isolated or syndromic forms....

Bevacizumab or PARP-Inhibitors Maintenance Therapy for Platinum-Sensitive Recurrent Ovarian Cancer: A Network Meta-Analysis.

Introduction: Targeted agents such as bevacizumab (BEV) or poly (ADP-ribose) polymerase inhibitors (PARPi) which have been added as concomitant or maintenance therapies have been shown to improve progression-free survival (PFS) in patients with platinum-sensitive recurrent ovarian cancer (PS rOC). In the absence of direct comparison, we performed a network meta-analysis considering BRCA genes status. Methods: We searched PubMed, EMBASE, and MEDLINE for trials involving patients with PS rOC treated with BEV or PARPi. Different comparisons were performed for patients included in the PARPi trials, according to BRCA genes status as follows: all comers (AC) population, BRCA 1/2 mutated (BRCAm), and BRCA wild type patients (BRCAwt). Results: In the overall population, PARPi prolonged PFS with respect to BEV (hazard ratio (HR) = 0.70, 95% CI 0.54–0.91). In the BRCA mutated carriers, the PFS improvement in favor of PARPi appeared to be higher (HR = 0.46, 95% CI 0.36–0.59) while in BRCAwt patients the superiority of PARPi over BEV failed to reach a statistically significance level (HR = 0.87, 95% CI 0.63–1.20); however, according to the SUCRA analysis, PARPi had the highest probability of being ranked as the most effective therapy (90% and 60%, for PARPi and BEV, respectively). Conclusions: PARPi performed better as compared with BEV in terms of PFS for the treatment of PS rOC, especially in BRCAm patients who had not previously received PARPi.

Hypersensitivity to platinum salts according to BRCA status in ovarian cancer: Retrospective analysis of clinical outcomes.

6053 Background: Hypersensitivity reactions (HSRs) to platinum salts are an important issue in the treatment of ovarian cancer (OC) patients (pts). Few data suggest that, along with number of previous cycles, germline BRCA mutations could be a risk factor. We aimed at evaluating the incidence and severity of HSRs to platinum salts in a large group of OC pts with known BRCA status and correlated them with drug exposure time. Methods: Between March 2003 and September 2019, 432 pts with a diagnosis of OC and a known BRCA status, were recorded in our 5 Institutions and retrospectively analyzed. The following data were collected: histology, BRCA status, type of surgery and first line therapy, number of total lines and cycles received, line and cycle of HSR onset, symptoms, history of other allergies and if desensitization was attempted. We graded the severity of HSRs according to CTCAE v5.0. We calculated the total duration of exposure to platinum salts, summing up the duration of all platinum lines received by the pts. Results: Four hundred nine of 432 (94.7%) pts were treated with at least one platinum-based line of therapy and were eligible for the analysis. Among them, 314 pts were BRCA wild type (BRCAwt) (76.8%) and 95 were BRCA mutated (BRCAmut) (23.2%). There was no statistical difference in number of prior lines of therapy [median 1 (2-6) for BRCA wt and 2 (1-6) for BRCAmut pts (p = 0.194)] and duration of exposure to platinum [median 126 (42 – 893) and 197 (42 – 896) days for BRCAwt and BRCAmut pts, respectively (p = 0.145)]. Incidence of any grade HSRs was 29 / 314 (9.2%) among BRCAwt pts vs. 17/ 95 (17.9%) among BRCAmut pts (Odds ratio [OR] 0.47, 95% CI 0.24 – 0.89, p= 0.019). All recorded HSRs to platinum salts were related to carboplatin. We observed a numerically higher incidence of Grade 3-4 HSRs in BRCAmut pts (5.1% in BRCAwt vs. 10.5% in BRCAmut cohort, OR 0.46, 95% CI 0.20 – 1.04, p = 0.057). The risk to develop HSRs increases with duration of exposure to platinum, particularly in BRCAmut pts. The cumulative incidence of any grade HSRs was 20.6% vs. 23.3% after 12 months and 38.4% vs. 59.7% after 18 months in BRCAwt and BRCAmut pts, respectively (Hazard Ratio [HR] 1.72, 95% CI 0.94 – 3.12, p = 0.073). The cumulative incidence of severe HSRs was 10.9% vs. 15.7% after 12 months and 26.5% vs. 41.0% after 18 months in BRCAwt and BRCAmut pts, respectively (HR 1.88, 95% CI 0.85 – 4.16, p = 0.11). Conclusions: In BRCAmut OC pts, there is a significantly higher incidence of HSRs to carboplatin, that seems not justified by longer drug exposure only.

NOGGO Ov-42/MAMOC: Rucaparib maintenance after bevacizumab maintenance following carboplatin-based first line-chemotherapy in ovarian cancer patients.

TPS6102 Background: Ovarian cancer (OC) is associated with the highest mortality rates among gynecological malignancies, with most patients being diagnosed in advanced stages. The most common histological subtype is high grade serous OC, which is characterized by deficiency in homologous recombination. Debulking surgery, followed by platinum based chemotherapy and bevacizumab (bev), followed by maintenance therapy with bev, is the standard therapy for advanced BRCA wild type (BRCAwt) OC patients in Germany. BRCA mutant patients will receive maintenance with olaparib, according to SOLO1 data. The anticancer effects of PARP inhibitors (PARPi) seem to be increased by the addition of antiangiogenic drugs. Preclinical data showed increased HRD in tumors pretreated with bev, and clinical trials showed a benefit of the combination of antiangiogenic drugs and PARPi vs. PARPi alone. NOGGO Ov-42/MAMOC trial (NCT04227522) is a phase III, randomized, placebo-controlled study evaluating rucaparib maintenance following bevacizumab maintenance for the treatment of advanced primary high grade BRCAwt OC. Methods: 190 patients with histologically confirmed advanced (FIGO stage IIIA- IV of the 2014 FIGO classification) high grade serous or high grade endometrioid (based on local histopathological findings) OC, fallopian tube cancer, primary peritoneal cancer or clear cell carcinoma of the ovary will be randomized 2:1 to receive either rucaparib 600mg BID or placebo as maintenance therapy following first line chemotherapy with 6 cycles of Carboplatin/Paclitaxel and at least 12 cycles of bev, given together with chemotherapy and as maintenance. Only BRCAwt patients will be included in the trial. Randomization is stratified by surgery planned timepoint (neoadjuvant vs. adjuvant), surgical outcome (no residual tumor mass vs. residual tumor mass), response to chemotherapy followed by bev (CR/NED vs. PR/SD) and study center. Treatment will continue for 24 months or until disease progression, unacceptable toxicity, or withdrawal. Primary endpoint is PFS in BRCAwt patients per RECIST v1.1. Secondary endpoints are PFS2, quality of life (EORTC QLQ-C30/OV28, FSI, SF-12, PROC-CTCAE, every day memory questionnaire), daily activity, time to next medical intervention, time to next subsequent therapy, safety assessments and OS. Clinical trial information: NCT04227522.

Frequency of brain metastases in patients with locally advanced triple negative breast cancer after neoadjuvant platinum-based chemotherapy: Impact of BRCA1/2 mutations.

1079 Background: patients with triple negative breast cancer has poor survival outcomes. Achievement of pathological complete response (pCR) after neoadjuvant chemotherapy can significantly improve survival of these patients, however some patients will relapse even after pCR. Methods: we reviewed prospectively-maintained outcomes database of N.N. Blokhin NMRCO. We extracted information about patients with locally advanced non-metastatic (stage IIIA-IIIC) triple negative breast cancer who were treated with neoadjuvant platinum based chemotherapy in 2014-2018 years. All included patients were tested for the presence of BRCA1/2 mutation with whole-exome next-generation sequencing or for “founder” hot-spot mutations. Results: we identified 80 patients who received neoadjuvant treatment with various platinum-based regimens. Pathological complete response rate was 62.5%. BRCA-mutations was found at 22 (27.5%) patients. Median follow-up time was 35.6 months (17.0 – 61.3). 2-year DFS was 77.3%, and 3-year DFS was 70.0%, there was significant differences in DFS in patients, who achieved and patients with residual tumor – 85,2% vs 64,3% (p=0,028). 2-year OS was 91%, 3-year OS was 78,5%. 18 patient had disease progression, the most common sites of disease progression were brain (9 [50.0%]), lungs (5 [27.8%]), 3 (16.7%) patients had locoregional relapses and 1 (5,6%) liver metastases. We separately analysed characteristics of patients with brain metastases (table). There were no significant differences in tumour pathologic response and patient age. All patients, who relapced after pCR, had brain metastases. We also found, that 7 of 9 patients with brain metastases had different BRCA mutations. Brain metastases developed in 40,9% (9/22) of patients with BRCA1 mutations and 3,4% (2/58) of patients with wild type BRCA1 (p<0,00001). Conclusions: BRCA1 mutation is significant prognostic factor for brain metastases development in locally advanced triple negative breast cancer. [Table: see text]

Comparison of poly(ADP-ribose) polymerase inhibitors (PARPi's) as maintenance therapy for platinum-sensitive ovarian cancer: Systematic review and network meta-analysis.

e18070 Background: Over the past decade, 3 PARPi's (olaparib, niraparib and rucaparib) have been approved by the FDA as maintenance therapy for recurrent ovarian cancer. However, thus far, no trial compared the 3 approved PARPi's in the overall population, in patients with BRCA mutations (BRCAm), or in those with wild-type BRCA (BRCAwt). Methods: We performed a systematic review and identified relevant literature from Embase, Pubmed and Cochrane Library. To be included in the analysis, studies had to be phase 2 or 3 randomized controlled trials (RCT) of platinum-sensitive recurrent or newly diagnosed ovarian cancer, randomized to placebo or PARPi as maintenance therapy and where complete or partial response was documented. A frequentist network meta-analysis was used for indirect comparisons between the different PARPi's to assess superiority in terms of progression free survival (PFS), overall survival (OS), and adverse events. Results: Overall, 6 RCTs involving 2,770 patients, were included in the network meta-analysis. Results from the indirect comparisons revealed no statistically significant differences between the 3 different PARPi's with respect to OS. PFS results demonstrated a nonsignificant trend supporting superiority for niraparib in all patients as well as in BRCAm patients (Table). Only 2 studies reported OS results for niraparib and none reported OS results for rucaparib. Niraparib showed a statistically significant increased risk for all grade thrombocytopenia and neutropenia. Conclusions: Our analysis demonstrates no statistically significant differences between the 3 PARPi’s in any of the analyzed groups, and a trend supporting PFS superiority for niraparib in all patients and in BRCAm patients, while having greater risk for thrombocytopenia and neutropenia. Additional OS results are pending from current studies, and would be useful for elucidating the relative roles of the different PARPi's in platinum-sensitive ovarian cancer. [Table: see text]

PFS by blinded independent central review (BICR) in the VELIA trial of veliparib (V) plus carboplatin/paclitaxel (CP) and as monotherapy in newly diagnosed patients (pts) with high-grade serous ovarian cancer (HGSC).

6077 Background: The phase III VELIA trial (NCT02470585) demonstrated statistically significant improvement in PFS per investigator (INV) for V added to CP and continued as maintenance (CPV-V) vs. CP alone in pts with newly diagnosed HGSC in the BRCA mutated ( BRCAm), homologous recombination deficient (HRD), and whole populations. Here we present pre-specified analyses of PFS per BICR. Methods: Pts with Stage III-IV HGSC received V or Placebo (PL) with CP (6 cycles) and as maintenance (30 additional cycles). Primary analysis of PFS by INV compared CPV-V to CP alone in the BRCAm, HRD, and whole populations. Exploratory analyses of PFS in BRCA wildtype (wt) and non-HRD HGSC were performed. Radiologic tumor assessments were also prospectively submitted to an independent central reviewer for blinded assessment per RECIST v 1.1. PFS per BICR and rates of concordance between INV and BICR for determination of disease progression were analyzed. Safety data from the primary analysis were previously reported. Results: 1140 total pts were enrolled (CPV-V 382; CP 375). In the whole population, 26% of HGSCs were BRCAm and 55% were HRD. Concordance rates between INV and BICR were 68-85% by arm for each population. Analyses of PFS per BICR and per INV were consistent (Table). PFS was prolonged in the CPV-V vs. CP arm in all primary and exploratory populations assessed. Conclusions: Analyses of PFS per BICR supported the primary analysis of PFS per INV in the BRCAm, HRD, and whole populations, as well as exploratory BRCAwt and non-HRD populations. Median PFS per BICR was longer compared to PFS per INV assessments in all populations and in both arms. These findings support the reliability of PFS by INV in ovarian cancer trials. Alternate strategies like audits may be appropriate to support PFS by INV with less time and expense than full BICR. Clinical trial information: NCT02470585. [Table: see text]

Real-world treatment patterns of maintenance therapy in platinum-sensitive recurrent epithelial ovarian cancer: Are some patients missing out?

e18042 Background: The clinical utility of maintenance therapy (MT) for patients with platinum-sensitive recurrent ovarian cancer (PSROC) has been validated in several clinical trials. We assessed real world treatment patterns using a US nationwide electronic health record database. Methods: A retrospective study of patients with PSROC between March 2017 and July 2019 was conducted using the Flatiron Health database. This longitudinal, demographically and geographically diverse de-identified database covers > 2.2 million oncology patients in > 280 cancer clinics. Patients were excluded if second or third line (2L or 3L) platinum-based chemotherapy (PBT) regimens included less than four or more than eight cycles of platinum. Information regarding somatic or germline BRCA mutations and homologous recombination deficiency (HRD) were obtained. Results: 2292 patients with PSROC were identified (had 2L or 3L treatment); 1214 of these received PBT at recurrence; 610 completed the PBT for recurrence on or after March 2017; 351 received 4–8 cycles of PBT; 225 patients had ≥2 months of active surveillance or were receiving MT of PARPi or bevacizumab (B) and were included in this analysis. 183 patients (80%) had BRCA testing and 14 patients (6%) had HRD testing. 46 (20%) had a germline or somatic BRCA mutations (t BRCA), 134 (59%) had a wildtype wt BRCA gene, and 48 (21%) were unknown. Of patients with tBRCA, 63% received a PARP inhibitor (PARPi), 17% received B, 20% received active surveillance. Of patients with wt BRCA, 40% received a PARPi, 24% received B, and 37% received active surveillance. Olaparib was the most commonly used PARPi among tBRCA patients (26%), while niraparib was most commonly used among wt BRCA patients (21%). MT was more common in younger patients, those with a better performance status and with a BRCA mutation. MT use trend increased by 21% during the study period. As PARPi use increased, the use of active surveillance as a post-platinum regimen decreased during the later time periods (Table). Conclusions: In this real world population, the majority of patients with PSROC are receiving maintenance therapy. While genetic testing is improving, universal testing of all patients with ovarian cancer remains the goal. The results provide insight into the shifting treatment patterns for patients with ovarian cancer. [Table: see text]

Functional evaluation of five BRCA2 unclassified variants identified in a Sri Lankan cohort with inherited cancer syndromes using a mouse embryonic stem cell-based assay

Next-generation sequencing of Sri Lankan families with inherited cancer syndromes resulted in the identification of five BRCA2 variants of unknown clinical significance. Interpreting such variants poses significant challenges for both clinicians and patients. Using a mouse embryonic stem cell-based functional assay, we found I785V, N830D, and K2077N to be functionally indistinguishable from wild-type BRCA2. Specific but mild sensitivity to olaparib and reduction in homologous recombination (HR) efficiency suggest partial loss of function of the A262T variant. This variant is located in the N-terminal DNA binding domain of BRCA2 that can facilitate HR by binding to dsDNA/ssDNA junctions. P3039P is clearly pathogenic because of premature protein truncation caused by exon 23 skipping. These findings highlight the value of mouse embryonic stem cell-based assays for determining the functional significance of variants of unknown clinical significance and provide valuable information regarding risk estimation and genetic counseling of families carrying these BRCA2 variants.

SAT-728 The Regulation of Tumor Suppressor Genes P53, BRCA-2, and Cell Cycle Protein p21 by Bisphenol S (BPS) in MCF-7 and T47-D Breast Cancer Cells

Bisphenol A (BPA) is considered to be an endocrine disrupting chemical (EDC), which mimics endogenous hormones and is linked to various cancers. Bisphenol S (BPS) is a BPA analogue, often used in plastics. BPS can leach into food and drink products, exposing humans to these chemicals. Evidence suggests BPS is also an EDC with similar endocrine disrupting effects. Despite hopes for a safer alternative, research has shown BPS possesses estrogenic activity due to its structural similarities with its analogue BPA. Previously we have shown the effects of BPS on estrogen receptor-alpha (ERα) and BRCA-1 in both MCF-7 and T-47D breast cancer cells. The wild-type p53 and BRCA-2 work to prevent cancer by monitoring and repairing DNA damage; however, in breast cancer patients these genes are often mutated. Mutated p53 will induce the cell cycle protein p21 to act as an oncogenic transcription factor. In the present study, we have examined the effects of BPS, alone and in combination with hormones and anti-hormones, on p53, BRCA-2, and p21 in both MCF-7 and T-47D cell lines by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assay, and RT-qPCR analyses. Western blot studies revealed alterations in the expression of p53, BRCA-2, and p21 related with varying concentrations of BPS (4-20 µM). In comparison to the control, p53 expression increased (65-95%) in the presence of BPS in both MCF-7 and T-47D cells. In addition, BRCA-2 expression revealed a similar increase in both cell lines when treated with BPS. However, p21 expression decreased (approximately 50%) with increasing concentrations in both cell lines. For further evaluation, an optimal concentration of 8 µM BPS was then used in combination with various hormones and anti-hormones. Compared to the control, BPS and E2 were up regulated in a similar fashion to p53. A similar trend in the effects on BRCA-2 expression was depicted in T-47D and MCF-7 cells. However, in p21, BPS and E2 were down regulated in both MCF-7 and T-47D breast cancer cells. In order to determine the influence of BPS on the growth of breast cancer cells, image cytometric analysis with propidium iodide staining was utilized to quantify alterations in T-47D and MCF-7 cell numbers and viability. Upon treatment of BPS concentrations (4-20 µM), an increase in cellular proliferation (12-60% increase) occurred in both cell lines. These cellular proliferative effects of BPS and E2 were sensitive to combination treatments with anti-estrogens. Confocal microscopy was utilized to examine the cytolocalization of p53 upon exposure to BPS alone and in combination with hormones and anti-hormones. The results from this study will yield a greater understanding of the molecular regulation of BPS action via the p53, BRCA-2, and p21 signaling pathways linked with breast cancer.

Therapeutic Potential of Combining PARP Inhibitor and Immunotherapy in Solid Tumors.

Immunotherapy has revolutionized the treatment of both hematological malignancies and solid tumors. The use of immunotherapy has improved outcome for patients with cancer across multiple tumor types, including lung, melanoma, ovarian, genitourinary, and more recently breast cancer with durable responses seen even in patients with widespread metastatic disease. Despite the promising results, immunotherapy still helps only a subset of patients due to overall low response rates. Moreover, the response to immunotherapy is highly cancer specific and results have not been as promising in cancers that are considered less immunogenic. The strategies to improve immunotherapy responses have focused on biomarker selection, like PD-L1 status, and usage of combinatorial agents, such as chemotherapy, targeted therapy, and radiotherapy. Of particular interest, DNA-damaging agents have the potential to enhance the response to immunotherapy by promoting neoantigen release, increasing tumor mutational burden, and enhancing PD-L1 expression. Poly-ADP-ribose polymerase (PARP) inhibitors are one such class of drugs that has shown synergy with immunotherapy in preclinical and early clinical studies. PARP-based therapies work through the inhibition of single-strand DNA repair leading to DNA damage, increased tumor mutational burden, making the tumor a more attractive target for immunotherapy. Of the solid tumors reviewed, breast, ovarian, and prostate cancers have demonstrated efficacy in the combination of PARP inhibition and immunotherapy, predominately in BRCA-mutated tumors. However, initial investigations into wildtype BRCA and gastrointestinal tumors have shown moderate overall response or disease control rates, dependent on the tumor type. In contrast, although a number of clinical trials underway, there is a paucity of published results for the use of the combination in lung or urothelial cancers. Overall this article focuses on the promise of combinatorial PARP inhibition and immunotherapy to improve patient outcomes in solid tumors, summarizing both early results and looking toward ongoing trials.

Long-term response to Olaparib in carcinomatous meningitis of a BRCA2 mutated ovarian cancer: A case report.

PARP inhibitors are considered as a treatment revolution in ovarian cancer management. Leptomeningeal metastasis is a rare event with poor prognosis. The present report presents an exceptional history of long term survival for a young patient treated with olaparib for carcinomatous meningitis. A 54-year-old woman was diagnosed with ovarian cancer. After Paclitaxel and Carboplatin treatment, followed by a debulking surgery and several lines of chemotherapy due to progression, the patient's disease evolved into carcinomatous meningitis within 6 months after the end of treatment. During care, exome analysis on brain lesions was performed. Exome analysis was performed with a mean coverage of 80X by a paired-end sequencing on an Illumina NextSeq500 device. Following bioinformatics alignment and variant annotation, a pathogenic BRCA2 mutation, c.7617+1G>T, was observed, and this was already detected in her family. Additionally, the allelic frequency observed indicated that the mutation was present at the homozygous status in tumor cells. Due to the presence of a pathogenic mutation and a loss of wild-type BRCA2 allele, a maintenance treatment by Olaparib was initiated after radiotherapy and Cisplatin monotherapy. The patient received olaparib treatment for 14 months with a very good disease control and an excellent tolerance. Despite long control, the patient succumbed to meningeal and peritoneal progression.

Efficacy and safety of PARP inhibitors as the maintenance therapy in ovarian cancer: a meta-analysis of nine randomized controlled trials.

Purpose: Poly ADP ribose polymerase (PARP) inhibitors can effectively kill cancer cells by restraining the activity of DNA repair enzymes and utilizing the characteristics of BRCA mutations. This article evaluates the efficacy and safety of PARP inhibitors (PARPis) in the maintenance treatment of ovarian cancer.Method: We searched for clinical trials in electronic databases. PARPis efficacy were evaluated by the hazard ratios (HR) and its 95% confidence intervals (95% CI) of overall survival (OS) and progression-free survival (PFS) between the PARPis groups and placebo groups, while the PARPis’ safety was assessed by relative risk (RR) values of adverse events (AEs) between the two arms.Results: The immature OS data manifested that patients with BRCA mutation receiving PARPis therapy versus placebo therapy appeared to have longer OS (HR = 0.78, 95%CI = 0.61–1.01; P = 0.06). Compared with placebo group, PARP group had a significant advantage in PFS in ovarian cancer patients with BRCA wild-type (BRCAwt), BRCA mutation (BRCAm), BRCA status unclassified, BRCA1 mutation subgroup and the BRCA2 mutation subgroup (BRCAwt: HR = 0.53, 95%CI = 0.42–0.68, P < 0.00001; BRCAm: HR = 0.30, 95%CI = 0.26–0.34, P < 0.00001; BRCA status unclassified: HR = 0.52, 95%CI = 0.41–0.66, P < 0.00001; BRCA1m: HR = 0.38, 95%CI = 0.29–0.48, P < 0.00001; BRCA2m: HR = 0.23, 95%CI = 0.10–0.57, P = 0.001). Our analysis revealed the incidence rates for AEs of grade ≥3 (grades 3 to 4) and serious AEs in PARPis group were 55.19% and 26.29%, respectively.Conclusion: Our meta-analysis demonstrates that PARPis therapy can significantly improve PFS in ovarian cancer patients, but it has no benefit in OS. However, the therapy is associated with a significant increase in the risk of AEs of grade ≥ 3 and serious AEs.

Ectopic RNF168 expression promotes break-induced replication-like DNA synthesis at stalled replication forks.

The RNF168 E3 ubiquitin ligase is activated in response to double stranded DNA breaks (DSBs) where it mono-ubiquitinates γH2AX (ub-H2AX). RNF168 protein expression and ubiquitin signaling are finely regulated during the sensing, repair and resolution of DNA damage in order to avoid excessive spreading of ubiquitinated chromatin. Supra-physiological RNF168 protein expression levels have been shown to block DNA end resection at DSBs and increase PARP inhibitor (PARPi) sensitivity. In this study, we examined the impact of ectopic RNF168 overexpression on hydroxyurea (HU)-induced stalled replication forks in the setting of BRCA1 deficiency. Surprisingly, RNF168 overexpression resulted in the extension of DNA fibers, despite the presence of HU, in BRCA1 deficient cells. Mechanistically, RNF168 overexpression recruited RAD18 to ub-H2AX at HU-induced DNA breaks. Subsequently, a RAD18-SLF1 axis was responsible for initiating DNA synthesis in a manner that also required the break-induced replication (BIR) factors RAD52 and POLD3. Strikingly, the presence of wild-type BRCA1 blocked RNF168-induced DNA synthesis. Notably, BIR-like repair has previously been linked with tandem duplication events found in BRCA1-mutated genomes. Thus, in the absence of BRCA1, excessive RNF168 expression may drive BIR, and contribute to the mutational signatures observed in BRCA1-mutated cancers.