Patients Carrying BRCA Mutations Research Articles

Abstract 6112: Automated scoring to assess RAD51-mediated homologous recombination in patient-derived tumor organoids of ovarian cancers

Abstract Extensive trials of PARP inhibitors (PARPi) have shown that they improve progression-free survival in patients with various cancers, including ovarian cancers. This improvement is marked in patients carrying BRCA mutations, and in Homologous Recombination Deficiency (HRD) subgroups. To date, identifying patients eligible for PARPi has been a challenge for scientific and clinical teams using next-generation sequencing (NGS) analysis and the persistence of genomic scars in tumors after restoration of proficient HR or epigenetic changes is a limitation of NGS. Functional assays could be used to improve the profiling of HR status and faithfully identify HRD tumors. The Repair Capacity Test assesses the formation of RAD51 foci in proliferating cells after irradiation and can be used on fresh primary cancer tissues irradiated ex vivo as well as on Patient-Derived Tumor Organoids (PDTO). However, RAD51 foci scoring is often performed manually without any possibility for the standardization of techniques. By contrast, recent progress in whole slide imaging referring to scan a complete microscope slide and creating a single high-resolution digital file, could represent an opportunity for automatizing the evaluation of HR. The purpose of this translational study was to develop an automated tool for scoring RAD51-mediated homologous recombination, to use this tool on ovarian PDTO and to compare the result to the sensitivity to olaparib (PARPi), determined by direct exposure of PDTO to the drug. We show that immunofluorescence of RAD51 foci can be automatically detected and quantified in Cyclin A2 positive nuclei in all the cells of each PDTO slice thus offering a new opportunity for the routine management and standardization of HR assessment in PDTO that goes beyond the widely used manual estimation. Finally, this automated scoring will be optimized to directly assess HR on tumor slices to make the Repair Capacity Test a highly relevant functional precision oncology tool to identify patients who will benefit from PARPi. Citation Format: Lucie Thorel, Pierre-Marie Morice, Nicolas Elie, Louis-Bastien Weiswald, Romane Florent, Florence Giffard, Margaux Jacobs, Agathe Ricou, Raphaël Leman, Guillaume Babin, Jean-François Lebrun, Sandrine Martin, Mélanie Briand, Benoit Goudergues, Bernard Lambert, Cécile Blanc-Fournier, Dominique Vaur, Benoit Plancoulaine, Laurent Poulain. Automated scoring to assess RAD51-mediated homologous recombination in patient-derived tumor organoids of ovarian cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6112.

Chemotherapy Toxicity in BRCA Mutation Carriers Undergoing First-Line Platinum-Based Chemotherapy.

BRCA mutations are the most frequent mutations causing homologous recombination defects in epithelial ovarian cancers (EOC). Germline mutation carriers are heterozygous for the mutation and harbor one defective allele in all cells. This has been hypothesized to cause increased susceptibility to DNA damage in healthy cells as well as neoplastic ones. Our objective was to assess chemotherapy-associated toxicities in patients with epithelial ovarian cancer with and without a germline BRCA mutation. A retrospective cohort study of patients with EOC receiving first-line platinum-based chemotherapy at a single center between 2006 and 2016. Indices of chemotoxicity, including blood counts, transfusion requirements, granulocyte colony-stimulating factor (gCSF) prescriptions, episodes of febrile neutropenia, and treatment delays were compared for BRCA mutation carriers and noncarriers. A total of 90 women met the inclusion criteria, including 31 BRCA mutation carriers (34%) and 59 noncarriers (66%). Mean hemoglobin, neutrophil count, and platelet counts during treatment were comparable for the two patient groups. There was a trend toward a higher frequency of hematological events in BRCA mutation carriers (neutropenia <1500 per mL: 6% vs. 0%, p = .12; thrombocytopenia <100,000 per mL: 23% vs. 9%, p = .07), but these differences were not statistically significant. Similarly, no significant differences were found in surrogates of bone marrow toxicity such as blood transfusions, use of gCSF, episodes of febrile neutropenia, or treatment delays. BRCA mutation carriers and noncarriers receiving first-line platinum-based chemotherapy for EOC have similar hematologic toxicity profiles. Clinicians treating these patients can be reassured that chemotherapy dosing or schedule do not require adjustment in patients carrying BRCA mutations. Patients with ovarian cancer carrying BRCA mutations are more likely to have serous tumors and present with higher CA125 levels. Germline BRCA mutation status is not associated with increased frequency of adverse hematologic events among patients with ovarian cancer being treated with first-line platinum-based chemotherapy. Germline BRCA mutations are also not associated with more treatment delays or a lower number of courses completed in this patient population. These findings should reassure practitioners engaged in care for patients with ovarian cancer that BRCA mutation status most likely will not affect chemotherapy dosing or schedule.

Predictive factors for prolonged response to olaparib as maintenance therapy in ovarian cancer patients with BRCA mutations.

5558Background: To investigate clinical factors predictive for prolonged progression-free survival (PFS) in ovarian cancer (OC) patients carrying BRCA mutations and receiving olaparib as a maintena...

TGFβ induces "BRCAness" and sensitivity to PARP inhibition in breast cancer by regulating DNA-repair genes.

Transforming growth factor beta (TGFβ) proteins are multitasking cytokines, in which high levels at tumor sites generally correlate with poor prognosis in human patients with cancer. Previously, it was reported that TGFβ downregulates the expression of ataxia telangiectasia-mutated (ATM) and mutS homolog 2 (MSH2) in breast cancer cells through an miRNA-mediated mechanism. In this study, expression of a panel of DNA-repair genes was examined, identifying breast cancer 1, early onset (BRCA1) as a target downregulated by TGFβ through the miR181 family. Correlations between the expression levels of TGFβ1 and the miR181/BRCA1 axis were observed in primary breast tumor specimens. By downregulating BRCA1, ATM, and MSH2, TGFβ orchestrates DNA damage response in certain breast cancer cells to induce a "BRCAness" phenotype, including impaired DNA-repair efficiency and synthetic lethality to the inhibition of poly (ADP-ribose) polymerase (PARP). Xenograft tumors with active TGFβ signaling exhibited resistance to the DNA-damaging agent doxorubicin but increased sensitivity to the PARP inhibitor ABT-888. Combination of doxorubicin with ABT-888 significantly improved the treatment efficacy in TGFβ-active tumors. Thus, TGFβ can induce "BRCAness" in certain breast cancers carrying wild-type BRCA genes and enhance the responsiveness to PARP inhibition, and the molecular mechanism behind this is characterized. These findings enable better selection of patients with sporadic breast cancer for PARP interventions, which have exhibited beneficial effects in patients carrying BRCA mutations.

Acute skin toxicity in Korean breast cancer patients carrying BRCA mutations

Purpose: In contrast to in vitro studies, most clinical trials testing the radiosensitivity of BRCA (Breast cancer susceptibility gene) mutations do not find a correlation between BRCA status and enhanced radiosensitivity. These trials include different ethnicities, and there is a lack of clinical data on BRCA1/2 mutation carriers and radiosensitivity in non-Caucasian patients. The goal of this study was to investigate acute skin toxicity, as a part of radiosensitivity, in breast cancer patients with BRCA1/2 mutations.Material and methods: BRCA mutation analysis was performed for 213 patients who underwent breast-conserving therapy using radiotherapy. Skin toxicity was scored according to the Radiation Therapy Oncology Group (RTOG) criteria during treatment and during one-month follow-up after radiation therapy.Results: Forty-six patients had BRCA1/2 mutations and 57 patients showed higher than grade 2 (RTOG) skin toxicity. In multivariate analysis, significant associations were found between mean breast volume and acute skin toxicity. BRCA mutation status, however, failed to show a significant correlation.Conclusions: Our results indicate that carriers of BRCA1/2 mutations among non-Caucasian breast cancer patients showed no enhancement in radiation sensitivity. Multiple genetic markers may be correlated with normal tissue responses after radiotherapy. Further studies are needed to identify genetic predispositions to normal tissue responses after radiotherapy.

PARP1 inhibitors attenuate AKT phosphorylation via the upregulation of PHLPP1

Poly(ADP-ribose) polymerase-1 (PARP1) inhibitors are emerging as an important class of drugs for treating BRCA-deficient cancers. Recent discoveries have shown that PARP1 inhibitors may treat other cancer patients in addition to the relatively small proportion of patients carrying BRCA mutations. However, the additional targets by which PARP1 inhibitor-mediated tumor suppression remain poorly understood. In this study, we show that two PARP1 inhibitors, PJ-34 and 3-AB, attenuate AKT phosphorylation at serine 473 (S473) independent of DNA repair impairment. These inhibitors decrease the AKT-associated phosphorylation of FOXO3A, enhance the nuclear retention of FOXO3A, and activate its transcriptional activity. We further demonstrate that treatment with PJ-34 or 3-AB dramatically increases the level of PHLPP1. Overexpression of PHLPP1 enhances the PARP1 inhibitor-induced downregulation of AKT phosphorylation and increases tumor cell death. In contrast, knockdown of PHLPP1 abrogates the PARP1 inhibitor-mediated AKT inhibition and desensitizes cells to its treatment. Therefore, our findings not only show the robust role of PARP1 inhibitors in AKT inhibition but also develop a novel strategy to increase the effectiveness of cancer treatment via PARP1 inhibitor-induced PHLPP1 upregulation.