BRCA1-associated Triple-negative Breast Cancer Research Articles

Mitomycin C in the treatment of early triple-negative locally advanced BRCA-associated breast cancer

Rationale. BRCA1 associated triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer. At the same time, carcinomas that develop in carriers of BRCA1 mutations are characterized by extremely high sensitivity to DNA-damaging chemotherapy. Mitomycin C alone or in combination with platinum agents has already demonstrated promising results in the treatment of BRCA-associated ovarian cancer (OC) and metastatic breast cancer. In this article, we present the results of a retrospective study aimed at comparing standard neoadjuvant chemotherapy regimens (NACT) with mitomycin-based regimens for primary locally advanced BRCA1-associated TNBC.The aim of the study is to determine the effectiveness of the combination of mitomycin and platinum compounds during neoadjuvant therapy in patients with primary locally advanced BRCA1 – associated TNBC.Materials and methods. The study included 89 patients diagnosed with primary locally advanced BRCA1-associated TNBC. Patients were divided into three groups depending on the therapy: 1) 4 cycles of anthracycline and cyclophosphamide followed by 12 weekly injections of paclitaxel (n = 48) (AC + T), 2) 4 cycles of anthracycline and cyclophosphamide followed by 12 weekly injections of paclitaxel and carboplatin (n = 27) (AC + TCbP), 3) mitomycin C plus platinum followed by 12 weekly injections of paclitaxel (n = 14) (MR + T). Pathological complete response (pCR) rates were compared.Results. The pCR rate in the MP+T group was 10/14 (71%). In patients with BRCA1-associated breast cancer who received AC + T and AC + TCbP regimens as NACT, the pCR rate was 17/48 (35%) and 19/27 (70%), respectively. The difference in pCR rate between mitomycin-containing therapy and the standard AC + T regimen was statistically significant (p = 0.03); the frequency of regressions was comparable to the frequency in the AC + TCbP group. During the 20-month follow-up period, no relapses were observed in the MR + T group. Relapses were more frequent in the AC + T group compared with the AC + TCbP group (16/48 (33%) vs 1/27 (4%), p = 0.003, Fisher’s exact test). The toxicity profile of the mitomycin-containing regimen included hematologic adverse events, the most common of which were anemia and leukopenia. Compared to standard regimens, nausea was significantly less pronounced. No patients reported alopecia with this regimen.Conclusions. The addition of mitomycin C to neoadjuvant therapy for BRCA1-associated TNBC may be a promising treatment option for this category of patients and merits further study.

Abstract 7120: Investigating PARP1 selective inhibitor DSB1559 efficacy in BRCA1-associated triple negative breast cancer

Abstract Background: Poly (ADP-ribose) polymerase inhibitors (PARPi) have improved outcomes of BRCA-associated breast cancer. However, toxicity can limit patient response as well as the ability to be combined with other therapeutics. Current PARPi broadly inhibit members of the PARP protein family, however only inhibition of PARP1 is needed for PARPi-mediated cell death. As inhibition of PARP2 is associated with hematological toxicity seen in PARPi patients, selectively inhibiting PARP1 may reduce PARPi toxicity and lead to better outcomes for patients. Here we characterize and test the efficacy of the PARP1 selective inhibitor (PARP1i) DSB1559 compared to Olaparib in BRCA1-associated triple negative breast cancer (TNBC). Methods: NanoBRET, PARylation, and pharmacokinetic/pharmacodynamic assays were performed to examine DSB1559 potency, PARP family selectivity, and in vivo behavior. Immunocompetent FVB/n mice bearing BRCA1-deficient TNBC (CMV-Cre;Brca1f/f;Trp53f/f) tumors were treated daily with PARPi (Olaparib) or PARP1i (DSB1559) for 60 days and followed for survival. CellTiter-Glo and qPCR assays were used to examine DSB1559 effect on cell viability and STING activation, respectively. Results: DSB1559 is a novel and potent PARP1 inhibitor which has superior selectivity for PARP1 compared to Olaparib and PARP1i AZD5305. DSB1559 has highly desirable physico-chemical and in vitro ADME properties, which translate to high oral bioavailability and moderate clearance in rodent PK studies. Additionally, DSB1559 demonstrated superior tumor residence time and tumor/plasma ratio compared to AZD5305. Compared to Olaparib, DSB1559 significantly increased STING activation and reduced cell viability in BRCA1-associated murine TNBC cells. BRCA1-associated TNBC-bearing immune-competent mice treated with DSB1559 had significantly reduced tumor growth and increased overall survival (median survival 74 days) compared to Olaparib (median survival 18 days). Analysis of changes in the tumor microenvironment are ongoing. Conclusions: Taken together, DSB1559 is a highly selective PARP1 inhibitor that demonstrates superior efficacy compared to Olaparib in a BRCA1-associated immune-competent TNBC model. Citation Format: Adam Nelson, Kelly F. Zheng, Carlos Wanderley, Daniel E. Michaud, Phillip M. Cowley, Gillian M. Campbell, Barry E. McGuinness, Alan Wise, Jennifer Guerriero. Investigating PARP1 selective inhibitor DSB1559 efficacy in BRCA1-associated triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7120.

Causes of resistance to PARP inhibitors and ways to overcome it. Case report of aggressive <i>BRCA</i>-related breast cancer

PARP inhibitors. However, in clinical practice, despite the proven antitumor efficacy of drugs, acquired resistance to PARP inhibitors leads to difficulties in selecting further therapy due unknown resistance mechanisms and absence of algorithm of action. Despite the various mechanisms of resistance to PARP inhibitors, the choice of subsequent combination therapy after the detection of resistance to PARP inhibitors should be based on an understanding of these mechanisms and the existence of heterogeneous metastatic process. At the same time, it is very important to study the molecular and genetic characteristics of the disease at each stage of progression, which will help to identify the cause of resistance and select the optimal treatment strategy. It seems that liquid biopsy of circulating tumor DNA, detection of circulating tumor cells, circulating microRNA or exosomes may be more suitable methods of molecular diagnostics than repeated biopsies. Currently, there are data on the identification of two types of resistance to PARP inhibitors: mechanisms independent and dependent on the BRCA1/2 gene and homologous DNA recombination repair (HRR) mechanisms. Strategies for using combinations of different therapeutic regimens in conjunction with PARP inhibitors are very promising options for preventing treatment resistance in view of the increasing number of patients with similar clinical course of the disease.In the presented clinical case, BRCA1-associated triple-negative breast cancer demonstrates an aggressive clinical course in case of adjuvant chemotherapy absence. Using the example of a clinical case, the effectiveness of therapy with the PARP inhibitor olaparib in disseminated BRCA1-mutated breast cancer, including those with brain metastases, was confirmed. At the same time, against the background of good tolerance and сlinical efficacy especially in the case of brain metastases, the use of the PARP inhibitor olaparib is a worthy alternative to chemotherapeutic regimens. The selection of subsequent therapy after a PARP inhibitor requires a balanced approach, taking into account the possible causes of crossresistance with chemotherapy regimens.

Targeting immunosuppressive macrophages overcomes PARP inhibitor resistance in BRCA1-associated triple-negative breast cancer.

Despite objective responses to PARP inhibition and improvements in progression-free survival compared to standard chemotherapy in patients with BRCA-associated triple-negative breast cancer (TNBC), benefits are transitory. Using high dimensional single-cell profiling of human TNBC, here we demonstrate that macrophages are the predominant infiltrating immune cell type in BRCA-associated TNBC. Through multi-omics profiling we show that PARP inhibitors enhance both anti- and pro-tumor features of macrophages through glucose and lipid metabolic reprogramming driven by the sterol regulatory element-binding protein 1 (SREBP-1) pathway. Combined PARP inhibitor therapy with CSF-1R blocking antibodies significantly enhanced innate and adaptive anti-tumor immunity and extends survival in BRCA-deficient tumors in vivo and is mediated by CD8+ T-cells. Collectively, our results uncover macrophage-mediated immune suppression as a liability of PARP inhibitor treatment and demonstrate combined PARP inhibition and macrophage targeting therapy induces a durable reprogramming of the tumor microenvironment, thus constituting a promising therapeutic strategy for TNBC.

Anti-EGFR monoclonal antibodies enhance sensitivity to DNA-damaging agents in BRCA1-mutated and PTEN-wild-type triple-negative breast cancer cells.

Increased epidermal growth factor receptor (EGFR) expression in triple-negative breast cancer (TNBC) is recognized as a promising therapeutic target, specifically through the use of selective EGFR inhibitors combined with chemotherapies. TNBC is characterized by genetic instability that leads to increased sensitivity to cytotoxic agents. We analyzed the effect of anti-EGFR monoclonal antibodies (mAbs; cetuximab and panitumumab) in combination with chemotherapeutic agents (docetaxel, cisplatin, and epirubicin) on EGFR-expressing TNBC cell lines that have different mutation statuses for one oncogene (KRAS) and two tumor suppressor genes (PTEN and BRCA1). Both mAbs failed to improve the cytotoxic effect of chemotherapies in the KRAS mutant cell line (MDA-MB-231) and PTEN-null cell lines (HCC-1937 and MDA-MB-468). In contrast, mAbs combined with DNA-damaging agents (cisplatin or epirubicin) had a synergistic effect in the BRCA1-mutant cell line SUM-1315 (wild-type KRAS and PTEN). The reintroduction of wild-type BRCA1 into SUM-1315 cells abolished this synergism. The improved effect of combination therapy was associated with cell cycle arrest at G1 phase and inhibition of the phosphorylation of EGFR and ERK1/2 proteins. These results suggest that patients with BRCA1-associated TNBC without genetic alterations in the PTEN and KRAS genes may have improved therapeutic responses to anti-EGFR mAbs combined with DNA-damaging agents. © 2017 Wiley Periodicals, Inc.

BRCA1-Associated Triple-Negative Breast Cancer and Potential Treatment for Ruthenium-Based Compounds.

Triple-negative breast cancer (TNBC) is defined by the absence of expression of estrogen receptor (ER), progesterone receptor (PR), and a lack of overexpression or amplification of human epidermal growth factor receptor 2 (HER2). The clinicopathological characteristics of TNBC include a high grading, a high rate of cell proliferation and a greater degree of chromosomal rearrangement. Patients with triple-negative breast cancer are more likely to be drug resistant and more difficult to treat, and are also frequently BRCA1 mutants. Methylation of the BRCA1 promoter region is associated with a reduction of the BRCA1 mRNA level. TNBC patients with a methylated BRCA1 had a better disease-free survival compared with those with non-methylated BRCA1. From a therapeutic perspective, the expression level of BRCA1 has been a major determinant of the responses to different classes of chemotherapy. BRCA1-dysfunctional tumors are hypersensitive to DNA damaging chemotherapeutic agents like platinum drugs. Although platinum based drugs are currently widely used as conventional chemotherapeutic drugs in breast cancer chemotherapy, their use has several disadvantages. It is therefore of interest to seek out alternative therapeutic metal-based compounds that could overcome the limitations of these platinum based drugs. Ruthenium-based compounds could be the most promising alternative to the platinum drugs. This review highlights the use of BRCA1 as a predictive marker as well as for a potential drug target for anticancer ruthenium compounds.

Neo-adjuvant doxorubicin and cyclophosphamide followed by paclitaxel in triple-negative breast cancer among BRCA1 mutation carriers and non-carriers.

The purpose of this study was to assess pathological complete response and whether it serves a surrogate for survival among patients receiving neo-adjuvant doxorubicin-cyclophosphamide followed by paclitaxel for triple-negative breast cancer with respect to BRCA1 mutation status. From a neo-adjuvant systemic therapy database of 588 breast cancer cases, 80 triple-negative cases who had undergone BRCA genotyping were identified. Logistic regression model was fitted to examine the association between BRCA1 status and pathological complete response. Survival outcomes were evaluated using Kaplan-Meier method, differences between study groups calculated by log-rank test. Thirty-four BRCA1 carriers and 43 non-carriers were identified. The BRCA1 carriers had pathological complete response rate of 68% compared with 37% among non-carriers, p=0.01. Yet this did not translate into superior survival for BRCA1 carriers compared with non-carriers. No difference in relapse-free survival were noted among those with or without pathological complete response in BRCA1 carriers regardless of pathological complete response status (Log-rank p=0.25), whereas in the non-carrier cohort, relapse-free survival was superior for those achieving pathological complete response (Log-rank p<0.0001). Response to neo-adjuvant systemic therapy differed in BRCA1-associated triple-negative breast cancer compared with triple-negative non-carriers, with a higher rate of pathological complete response. However, compared with non-carrier triple-negative breast cancer, pathological complete response was not a surrogate for superior relapse-free survival in BRCA1 patients. Future studies using specific chemotherapy regimens may provide further improvements in outcomes.

A potential role of EGFR-inhibitors for the prevention of BRCA1-related breast cancer.

Abstract Abstract #1110 Background: The majority of women who develop a BRCA1-related breast cancer develop an ER-/PR-/HER2- breast cancer. Endocrine prophylaxis does not prevent these ER- breast cancers. Therefore, there is a need to develop novel chemoprevention agents in this population. 67% of BRCA1-associated ER- breast cancers also overexpress epidermal growth factor receptor (EGFR). We therefore examined EGFR as a potential target for chemoprevention&amp;#x2028; Methods: We isolated primary mammary epithelial cells (HMECs) from women with a germline BRCA1 mutation who underwent prophylactic mastectomies and from age-matched controls without a mutation who underwent reduction mammoplasties. We used a three-dimensional matrigel-based colony formation assay to assess clonality and proliferative capacity of these cells as well as their response to EGFR-inhibition. Flow cytometry was used to determine the number of EGF binding sites per cell. As a corresponding mouse model we used conditional MMTV-Cre BRCA1-/-p53+/- mice. Results: HMECs from BRCA1 mutation carriers and from controls express EGFR to a similar extent as HCC1937 BRCA1-associated triple-negative breast cancer cells (5x103 binding sites/cell). In ex vivo 3D-cultures we observed that HMECs derived from BRCA1 mutation carriers showed greater clonal and proliferative capacity when compared to normal controls. However while the HMECs derived from BRCA1 mutation carriers and normal controls were equally sensitive to the growth-inhibitory effect of Erlotinib at concentrations as low as 0.2 μM, the ID50 for HCC1937 breast cancer cells was &amp;gt; 10 μM. Similar findings were observed in murine MECs derived from normal control mice as well as BRCA1-/-p53+/- mice which develop breast cancer at the age of 7 to 8 months. Both groups of murine MECs were equally sensitive to Erlotinib growth inhibition. Conclusion: MECs derived from breast tissue of women and mice with a germline BRCA1 mutation express EGFR and are highly sensitive to growth inhibition with the EGFR inhibitor Erlotinib. In contrast, BRCA1-associated HCC 1937 breast cancer cells are more resistant to Erlotinib inhibition despite EGFR expression. We are now studying whether Erlotinib given via oral gavage daily has the potential to delay or prevent breast cancer in this mouse model of BRCA1-related breast cancer. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1110.

Promotion of BRCA1-associated triple-negative breast cancer by ovarian hormones

Mammary epithelial proliferation is controlled by the ovarian hormones estrogen and progesterone. Although BRCA1 (breast cancer 1, early onset) is ubiquitously expressed, women with BRCA1 mutations have a propensity to develop tumors in tissues sensitive to ovarian hormone. An understanding of the tissue-specific function of the BRCA1-encoded protein (BRCA1) provides additional insight that may improve cancer risk reduction in BRCA1 mutation carriers. Studies using mouse models have shown that BRCA1 regulates the abundance of progesterone receptor. The half-life of progesterone receptor is extended in cells harboring mutations in BRCA1. Reduced ubiquitination of progesterone receptor contributes to its stabilization and is correlated with increased cell proliferation in response to progesterone. Treatment of mutant mice with antiprogesterone prevents/delays tumor development. In vitro, BRCA1 and its interacting protein BARD1 (BRCA1-associated RING domain) serve as an ubiquitin ligase for the monoubiquitination of estrogen receptor-alpha, which may lead to alterations in estrogen receptor-alpha activity. Furthermore, the ubiquitin ligase activities of BRCA1/BARD1 may be determined by the ubiquitin-conjugating enzyme E2. BRCA1 exerts its tissue-specific function through the regulation of progesterone receptor and estrogen receptor-alpha. Interference with progesterone receptor, in addition to estrogen receptor-alpha, may be effective in reducing cancer risk in BRCA1 mutation carriers.