Mutations In DNA Repair Genes Research Articles

Prevalence of DNA-Repair Gene Mutations in Mexican Men with Prostate Cancer

Introduction and objectiveMexico reported 26,742 new cases of prostate cancer in 2020. Different risk factors have been identified in the pathogenesis of prostate cancer. Among them, genetic factors and alterations or mutations in specific genes have been described in different ethnic groups worldwide. The aim of our study is to report the prevalence of germline DNA-repair gene mutations in Mexican patients with prostate cancer. Material and methodWe performed germline genetic testing in 50 patients with localized prostate cancer and 50 patients with metastatic prostate cancer. Demographic, clinical, and histopathological data were collected. ResultsThirty-seven germline mutations were identified in 32 patients. The most commonly affected genes were ATM in 6%, followed by FANCA (5%), and ATR (4%). BRCA2 mutations were identified in 3%. The frequency of mutations was higher in the metastatic group. Discussion and ConclusionThe results of our study show different mutations from those reported in different populations or regions. The use of PARP inhibitors is indicated in patients with germline mutations, specifically BRCA2, showing improvement in overall survival and progression free survival. To our knowledge, this is the first study reporting the prevalence of mutations in DNA-repair genes in Mexican patients with prostate cancer.

Synergistic Activity of DNA Damage Response Inhibitors in Combination with Radium-223 in Prostate Cancer.

Radium-223 (223Ra) and Lutetium-177-labelled-PSMA-617 (177Lu-PSMA) are currently the only radiopharmaceutical treatments to prolong survival for patients with metastatic-castration-resistant prostate cancer (mCRPC); however, mCRPC remains an aggressive disease. Recent clinical evidence suggests patients with mutations in DNA repair genes associated with homologous recombination have a greater clinical benefit from 223Ra. In this study, we aimed to determine the utility of combining DNA damage response (DDR) inhibitors to increase the therapeutic efficacy of X-rays, or 223Ra. Radiobiological responses were characterised by in vitro assessment of clonogenic survival, repair of double strand breaks, cell cycle distribution, and apoptosis via PARP-1 cleavage. Here, we show that DDR inhibitors increase the therapeutic efficacy of both radiation qualities examined, which is associated with greater levels of residual DNA damage. Co-treatment of ATM or PARP inhibition with 223Ra increased cell cycle arrest in the G2/M phase. In comparison, combined ATR inhibition and radiation qualities caused G2/M checkpoint abrogation. Additionally, greater levels of apoptosis were observed after the combination of DDR inhibitors with 223Ra. This study identified the ATR inhibitor as the most synergistic inhibitor for both radiation qualities, supporting further pre-clinical evaluation of DDR inhibitors in combination with 223Ra for the treatment of prostate cancer.

Prevalencia de mutaciones en genes de reparación en hombres mexicanos con cáncer de próstata

Introduction and objective: Mexico reported 26,742 new cases of prostate cancer in 2020. Different risk factors have been identified in the pathogenesis of prostate cancer. Among them, genetic factors and alterations or mutations in specific genes have been described in different ethnic groups worldwide. The aim of our study is to report the prevalence of germline DNA-repair gene mutations in Mexican patients with prostate cancer.Material and method: We performed germline genetic testing in 50 patients with localized prostate cancer and 50 patients with metastatic prostate cancer. Demographic, clinical, and histopathological data were collected.Results: Thirty-seven germline mutations were identified in 32 patients. The most commonly affected genes were ATM in 6%, followed by FANCA (5%), and ATR (4%). BRCA2 mutations were identified in 3%. The frequency of mutations was higher in the metastatic group.Discussion and Conclusion: The results of our study show different mutations from those reported in different populations or regions. The use of PARP inhibitors is indicated in patients with germline mutations, specifically BRCA2, showing improvement in overall survival and progression free survival. To our knowledge, this is the first study reporting the prevalence of mutations in DNA-repair genes in Mexican patients with prostate cancer.

Abstract 6414: Molecular differentiation between complete and incomplete responders to neoadjuvant therapy in rectal cancer

Abstract Neoadjuvant chemoradiotherapy (nCRT) is the standard treatment for locally advanced rectal cancer, but only 20-40% of patients completely respond to this treatment. This study aims to identify the molecular features associated with a response to nCRT. We generated and collected genomic and transcriptomic data from 712 cancers prior to treatment from our own data and from publicly available data. A comprehensive integrated analysis was performed. We found that patients with a complete response have decreased risk of both local recurrence and future metastasis. We identified multiple molecular differences between complete and incomplete responders. Complete responders have a higher tumor mutation burden and more significant co-occurring mutations than the incomplete responders. In addition, mutations in DNA repair genes were enriched in complete responders and they also had lower expression of these genes indicating that defective DNA repair is associated with complete response to nCRT. Using logistic regression, we identified three significant predictors of complete response: tumor size, mutations within specific network genes, and the existence of three or more specific co-occurrent mutations. In incompletely responder tumors, abnormal cell-cell interaction and increased cancer associated fibroblasts were associated with recurrence. Additionally, gene expression analysis identified a subset of immune hot tumors with worse outcomes and upregulation of immune checkpoint proteins. Our study directly informs the clinical management of rectal cancer by elucidating the molecular differences between tumors with complete and incomplete responses to neoadjuvant chemoradiotherapy (nCRT), as well as the features of tumors prone to recurrence. We have pinpointed critical molecular markers and clinical indicators—such as tumor size, specific gene mutations, and particular mutation patterns—that are significant predictors of treatment response. These findings offer valuable biomarkers for personalizing treatment strategies. Additionally, the observed mutation enrichment in DNA repair genes among complete responders suggests new avenues for therapeutic innovation. By highlighting the distinct molecular and immune profiles of non-responder tumors at higher recurrence risk, our research supports the advancement of precision oncology approaches, enhancing prognosis and treatment customization in rectal cancer care, ultimately striving to bridge the gap between scientific discovery and clinical application. Citation Format: Fengyuan Huang, M. Chandler McLeod, Regina Kay Irwin, Mary Smithson, Zongliang Yue, Min Gao, Karin M. Hardiman, Zechen Chong. Molecular differentiation between complete and incomplete responders to neoadjuvant therapy in rectal 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 6414.

Effect of inactivating heterozygous mutations in DNA repair genes on experimental lung carcinogenesis in mice

Background. Inactivating mutations in Chek2 and Gprc5a genes are known to be associated with cancer development. Experimental carcinogenesis studies in genetically modified mice generate new data on their influence on pathology development.Aim. In the present study in a model of lung carcinogenesis, survival parameters as well as tumor multiplicity and size in mice with Chek2 and Gprc5a heterozygous inactivating mutations were evaluated.Material and methods. F2 hybrid mice from crosses between CBAB6F1 males heterozygous for the studied mutations and wild-type BALB / c females were used: Chek2dAA-carriers (76 males and 64 females) and Gprc5ainsA-carriers (60 males and 42 females). Starting at four months of age, mice received urethane (ethyl carbamate) intraperitoneally at a dose of 600 mg / kg weekly for 6 weeks. After genotyping by allele-specific PCR, animals were allocated to groups. Carcinogenesis parameters were evaluated 40 weeks after the beginning of the experiment.Results. The proportion of mice with mutations surviving to the age of three months roughly followed the Mendelian distribution (35 / 41 males and 33 / 31 females) for the offspring of males heterozygous for Chek2dAA and was significantly lower in the case of Gprc5ainsA (20 / 40 males and 17 / 25 females, p = 0.043). The death of Gprc5ainsA carriers during the experiment was also higher than in the control group (p = 0.0506 in females). Synchronous lung and thymus neoplasms were found in 2 out of 4 Gprc5ainsA females that died before the end of the experiment, which were not found in other groups. At the end of the experiment, no significant differences in tumor multiplicity, mean linear size, and volume were found between the groups of mice with and without mutations.Conclusion. It was found that heterozygous inactivating mutation Chek2dAA does not affect early age development and does not modify the parameters of induced lung carcinogenesis in mice. Heterozygous carriage of Gprc5ainsA mutation in mice increases the risk of early death and sensitivity to the toxic and carcinogenic effects of urethane.

Sensing chemical-induced DNA damage using CRISPR/Cas9-mediated gene-deletion yeast-reporter strains

Microorganism-based genotoxicity assessments are vital for evaluating potential chemical-induced DNA damage. In this study, we developed both chromosomally integrated and single-copy plasmid–based reporter assays in budding yeast using a RNR3 promoter–driven luciferase gene. These assays were designed to compare the response to genotoxic chemicals with a pre-established multicopy plasmid–based assay. Despite exhibiting the lowest luciferase activity, the chromosomally integrated reporter assay showed the highest fold induction (i.e., the ratio of luciferase activity in the presence and absence of the chemical) compared with the established plasmid-based assay. Using CRISPR/Cas9 technology, we generated mutants with single- or double-gene deletions, affecting major DNA repair pathways or cell permeability. This enabled us to evaluate reporter gene responses to genotoxicants in a single-copy plasmid–based assay. Elevated background activities were observed in several mutants, such as mag1Δ cells, even without exposure to chemicals. However, substantial luciferase induction was detected in single-deletion mutants following exposure to specific chemicals, including mag1Δ, mms2Δ, and rad59Δ cells treated with methyl methanesulfonate; rad59Δ cells exposed to camptothecin; and mms2Δ and rad10Δ cells treated with mitomycin C (MMC) and cisplatin (CDDP). Notably, mms2Δ/rad10Δ cells treated with MMC or CDDP exhibited significantly enhanced luciferase induction compared with the parent single-deletion mutants, suggesting that postreplication and for nucleotide excision repair processes predominantly contribute to repairing DNA crosslinks. Overall, our findings demonstrate the utility of yeast-based reporter assays employing strains with multiple-deletion mutations in DNA repair genes. These assays serve as valuable tools for investigating DNA repair mechanisms and assessing chemical-induced DNA damage.Key points• Responses to genotoxic chemicals were investigated in three types of reporter yeast.• Yeast strains with single- and double-deletions of DNA repair genes were tested.• Two DNA repair pathways predominantly contributed to DNA crosslink repair in yeast.

The effect of NBS1 heterozygous inactivating mutation in a model of 7,12-dimethylbenz[a]anthracene-induced carcinogenesis in mice

BACKGROUND: The creation of new experimental models carrying various heterozygous inactivating mutations in DNA repair genes and their carcinogenesis studies could expand our understanding of the spectrum of possible neoplasms that patients with such mutations are at risk of developing.
 AIM: The study of the effect of NBS1 inactivating heterozygous mutation (с.1971insT, p.Arg658Stop) in a model of 7,12-dimethylbenz[a]anthracene (DMBA) induced carcinogenesis in mice.
 MATERIALS AND METHODS: Carcinogenesis was induced in 2-month-old female mice with and without NBS1 heterozygous mutation by intragastric administration of 7,12-DMBA (dose of 50 mg/kg once a week, for 8 weeks) on a high-fat diet. Lifetime observation was conducted, and parameters of lifespan and carcinogenesis were evaluated.
 RESULTS: NBS1 inactivating heterozygous mutation had no significant effect on the incidence of tumor pathology induced by 7,12-DMBA, but somewhat accelerated the rate of tumor development and, consequently, the death of animals. The presence of the mutation increased the sensitivity to carcinogen toxic effect, which was expressed in a statistically significant increase in death rate (by 35%) in the early stages of the study. The mean lifespan in female NBS1 mutant mice was reduced by 14% compared to mutation-free animals.
 CONCLUSION: Carrying NBS1 inactivating heterozygous mutation (с.1971insT, p.Arg658Stop) worsens the prognosis of survival in the model of chemically induced 7,12-DMBA carcinogenesis in mice.

Abstract LB_A03: Proximity ligation sequencing reveals novel and recurrent structural genomic variants in FFPE pancreatic ductal adenocarcinoma samples

Abstract Activating KRAS mutations, homologous recombination deficiency (HRD), deficient mismatch repair (dMMR), and other prognostic or predictive biomarkers are seen in fewer than half of pancreatic ductal adenocarcinoma (PDAC) cases. Structural variants (SV), such as gene fusions, translocations, deletions, duplications, etc, are known to play a role in oncogenesis, metastasis, and/or treatment resistance. In solid tumors, SV discovery and validation has been limited, often due to a fresh or live tissue requirement in cytogenomic analyses. Recent innovations in processing formalin-fixed paraffin-embedded (FFPE) samples for “next-generation” chromatin capture and long-range sequencing platforms (i.e. Hi-C) have overcome this barrier. Hi-C is a genome-wide technology which surveys rearrangements, generating genomic contiguity data from highly fragmented chromatin. Unlike targeted (e.g. hybrid capture) assays, Hi-C can survey the landscape of genomic aberrations in an unbiased manner. Archived FFPE has previously been an obstacle to Hi-C analysis of solid tumors. We present here, to our knowledge, the first Hi-C analysis of FFPE PDAC samples using a previously described, proprietary Hi-C platform. Thirty-one samples from 20 unique patients diagnosed and treated at the University of Colorado Comprehensive Cancer Center between 2014-2022 were processed and analyzed. Twenty-two samples were surgical resections paired with later biopsies of metastatic recurrences. Nine were unpaired surgical resections or metastatic biopsies. Seven of these cases had somatic KRAS mutations, five had germline mutations in DNA repair genes, and none had evidence of dMMR or MSI-high. Fifty percent of samples had sufficient tumor content for processing and successful library generation. Notably, two paired samples from 2014 were successfully processed and sequenced demonstrating the applicability of this technology to archival samples. In successfully analyzed samples, the vast majority of SVs observed in metastases were also seen in paired primary tumors. Several duplications and deletions recurred across two or more patients. Furthermore, at least three SVs from this cohort were observed in other tumor types from a separate cohort analysis using this technology. Cases with relatively more SVs demonstrated a longer time to metastatic recurrence than cases with fewer SVs. Cases with germline-mutated cancer-predisposing genes demonstrated a similar SV signature and time to metastatic recurrence as some cases with or without unknown germline and somatic tumor mutation status. Overall, our findings show that this novel platform can successfully profile archived FFPE PDAC samples. Some paired samples show a shared SV signature suggesting the presence of metastatic clones at the time of initial diagnosis. Following these results, we plan to process and analyze a larger cohort of PDAC cases enriched for wild-type KRAS and HRD carriers. We plan to compare our findings to Hi-C results from other tumors and further focus on any SVs recurrent across tumor types. Citation Format: Abhishek Pandey, Stephen Eacker, Adrie Van Bokhoven, Kathleen Torko, Christopher H Lieu. Proximity ligation sequencing reveals novel and recurrent structural genomic variants in FFPE pancreatic ductal adenocarcinoma samples [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_A03.

Liquid Biopsy as a Powerful Therapeutic Tool in Veteran Patients with Prostate Carcinoma

Abstract Introduction/Objective The National Comprehensive Cancer Network (NCCN) guidelines currently recommend somatic tumor molecular testing for alterations in homologous recombination (HR) DNA repair genes in patients with metastatic prostate cancer, which can be performed on either the sampled tumor tissue itself or by liquid biopsy. Particularly when the sampled tumor tissue may be limited, liquid biopsy with next generation sequencing is a recently available attractive alternative that is minimally invasive (requiring just phlebotomy). Based on the information gathered from circulating tumor cells (CTC), a tumor molecular profile can be obtained that can impact treatment, particularly if a HR DNA repair mutation is found as that may predict response to a poly (ADP-ribose) polymerase (PARP) enzyme inhibitor such as Olaparib. However, the literature of metastatic prostate cancers targeted by liquid biopsies and the mutations found is sparse, particularly for the veteran population. Methods/Case Report A retrospective review was performed of all patients with a submitted liquid biopsy specimen at a Veteran Affairs Medical Center (VAMC) October 23rd, 2019, to March 3rd, 2023 to examine those patients with metastatic prostate cancer. Information on mutations detected was collected. Results (if a Case Study enter NA) There were a total of 64 patient specimens with a history of metastatic prostate cancer, from which 56 had an available liquid biopsy report with the first liquid biopsy collection occurring on October 23rd, 2019. HR DNA repair mutations found included CHEK2 (6/56), ATM (4/56), and BRCA1 (1/56). Outside of HR DNA repair genes, relatively common detected mutations were found in TP53 (25/56), PTEN (6/56), BRAF (4/56), and an AR amplification (4/56). 7 of the 56 reports had no reportable genomic alterations detected. Conclusion Liquid biopsies continues to be a minimally invasive, highly useful powerful therapeutic tool in veteran patients with metastatic prostate carcinoma for molecular profiling. Not uncommonly in the Veteran population, these molecular findings include mutations in HR DNA repair genes that as noted by the NCCN may predict response to PARP inhibitor chemotherapy.

DNA damage response and repair gene mutations are associated with tumor mutational burden and outcomes to platinum-based chemotherapy/immunotherapy in advanced NSCLC patients

BackgroundDNA damage response and repair (DDR) genes are crucial for maintaining the integrity of the genome. This study aims to explore the correlation of DDR gene mutations with TMB, clinical characteristics, and outcomes to platinum-based chemotherapy and platinum-based chemotherapy/immunotherapy in non-small cell lung cancer (NSCLC) without EGFR and ALK alterations.MethodsTumor tissue from 49 patients with stage III or IV NSCLC who were without EGFR and ALK alterations were analyzed using targeted next-generation sequencing (NGS). Among them, 13 patients received first-line platinum-based chemotherapy, 32 patients received first-line platinum-based chemotherapy/immunotherapy.ResultsIn these NSCLC patients without EGFR and ALK alterations, the frequently mutated genes included TP53, KMT2D and KRAS, the most frequently mutated DDR gene was FANCG, DDR gene mutations were detected in 20 patients. The mutation frequency of homologous recombination (HR) pathway was significantly higher in lung squamous cell carcinoma (LUSC) than that in lung adenocarcinoma (LUAD) (30.8% vs. 5.7%). Among DDR positive patients, a lower percentage exhibited metastasis. Patients with DDR gene mutations, cell-cycle checkpoint pathway mutations, and BER pathway mutations had significantly higher TMB compared to those without corresponding mutations. In the patients receiving platinum-based chemotherapy/immunotherapy, the disease control rate was significantly lower in the DDR-positive group compared with that in the DDR-negative group (55.6% vs. 100.0%). Among LUAD patients receiving platinum-based chemotherapy/immunotherapy, we observed a worse overall survival (OS) in DDR-positive group, as well as poorer progression-free survival(PFS)and OS in BER-positive and FANCG mutated group.ConclusionsDDR gene mutations are associated with tumor metastasis, TMB, and outcomes to platinum-based chemotherapy/immunotherapy in advanced NSCLC patients.

The relationship of prostate cancer with mutations in tumour suppressor genes

Genetic testing plays an increasing role in the diagnosis of various diseases every year. Special attention is paid to genes with an increased risk of cancer in case of mutation. Hereditary prostate cancer is usually more aggressive and is most often associated with mutations in DNA repair genes. These mutations carriers have an increased risk of metastasis and a shorter life expectancy. The study of mutations in the BRCA1/BRCA2 genes is most often used in clinical practice, while there are many other genes responsible for DNA repair processes that have not been sufficiently studied. In this paper, we report a review of literature sources studying the cellular mechanisms of functioning of DNA repair genes, the effect of such mutations on the disease state and oncological outcomes.

Correction to: ORCHID: A phase II study of Olaparib in Metastatic Renal Cell Carcinoma Patients HarborIng a BAP1 or Other DNA Repair Gene Mutations.

Correction to: ORCHID: A phase II study of Olaparib in Metastatic Renal Cell Carcinoma Patients HarborIng a BAP1 or Other DNA Repair Gene Mutations.

Detection of Primary DNA Lesions by Transient Changes in Mating Behavior in Yeast Saccharomyces cerevisiae Using the Alpha-Test.

Spontaneous or induced DNA lesions can result in stable gene mutations and chromosomal aberrations due to their inaccurate repair, ultimately resulting in phenotype changes. Some DNA lesions per se may interfere with transcription, leading to temporary phenocopies of mutations. The direct impact of primary DNA lesions on phenotype before their removal by repair is not well understood. To address this question, we used the alpha-test, which allows for detecting various genetic events leading to temporary or hereditary changes in mating type α→a in heterothallic strains of yeast Saccharomyces cerevisiae. Here, we compared yeast strains carrying mutations in DNA repair genes, mismatch repair (pms1), base excision repair (ogg1), and homologous recombination repair (rad52), as well as mutagens causing specific DNA lesions (UV light and camptothecin). We found that double-strand breaks and UV-induced lesions have a stronger effect on the phenotype than mismatches and 8-oxoguanine. Moreover, the loss of the entire chromosome III leads to an immediate mating type switch α→a and does not prevent hybridization. We also evaluated the ability of primary DNA lesions to persist through the cell cycle by assessing the frequency of UV-induced inherited and non-inherited genetic changes in asynchronous cultures of a wild-type (wt) strain and in a cdc28-4 mutant arrested in the G1 phase. Our findings suggest that the phenotypic manifestation of primary DNA lesions depends on their type and the stage of the cell cycle in which it occurred.

The Clinical Significance of Genetic Variation in Ovarian Cancer.

Genetic variation is a well-known contributor to the onset and progression of cancer. The goal of this study is to provide a comprehensive examination of the nucleotide and chromosomal variation associated with the onset and progression of serous ovarian cancer. Using a variety of computational and statistical methods, we examine the exome sequence profiles of genetic variants present in the primary tumors of 432 ovarian cancer patient samples to compute: (1) the tumor mutational burden for all genes and (2) the chromosomal copy number alterations associated with the onset/progression of ovarian cancer. Tumor mutational burden is reduced in the late vs. early stages, with the highest levels being associated with loss-of-function mutations in DNA-repair genes. Nucleotide variation and copy number alterations associated with known cancer driver genes are selectively favored over ovarian cancer development. The results indicate that genetic variation is a significant contributor to the onset and progression of ovarian cancer. The measurement of the relative levels of genetic variation associated with individual ovarian cancer patient tumors may be a clinically valuable predictor of potential tumor aggressiveness and resistance to chemotherapy. Tumors found to be associated with high levels of genetic variation may help in the clinical identification of high-risk ovarian cancer patients who could benefit from more frequent monitoring.

Androgen receptor signaling mechanism in prostate cancer: resistance to antiandrogen therapy and association with DNA repair genes

Background. Metastatic castration-resistant prostate cancer remains a complex problem due to patients' previous treatments and limited selection of subsequent therapies. While 2nd generation antiandrogens are initially effective, resistance to them is not an exceptional event. Mechanisms depending on androgen receptor and independent of it have been described. A special focus is on mutations in DNA repair genes, particularly genes involved in homologous recombination repair (HRR) as a possible cause of somatic genetic abnormalities specifically in progressive metastatic disease. However, data on the effect of the HRR defect on the effectiveness of antiandrogen therapy for prostate cancer are very limited, which requires additional clinical studies.Aim. To evaluate the effect of clinical, morphological, molecular and genetic factors on the effectiveness of enzalutamide antiandrogen therapy in patients with prostate cancer and known mutations in DNA repair genes involved in HRR and mismatch repair.Materials and methods. The study was performed at the Clinical Oncological Dispensary No. 1 (Krasnodar). Retrospective analysis of clinical and morphological parameters of 54 patients with prostate cancer who received enzalutamide antiandrogen therapy and with known status of germ line and somatic mutations of HRR DNA repair genes (BRCA1, BRCA2, ATM, BARD, BRIP1, CDK12, CHEK1, CHEK2, PALB2, RAD51B, RAD51C, RAD54L, FANCL) and microsatellite instability in immunohistochemical determination of mismatch repair deficit was performed. Statistical analysis was performed using IBM SPSS Statistics v.22 software.Results and conclusion. In 17 of 54 patients, pathogenic germline and somatic mutations of HRR genes were detected: 7 mutations in BRCA2 gene, 4 - in CHEK2, 2 - in BRCA1, 2 - in CDK12, 1 - in BRIP1 and 1 - in ATM. It was shown that in the group of patients with metastatic castration-resistant prostate cancer, histological grade per the International Society of Urological Pathology (ISUP) G2 (total Gleason score 7 (3 + 4)) is significantly associated with the absence of HRR mutation, and grade G3 (total Gleason score 7 (4 + 3)) was associated with HRR mutations (р <0.05). Increase in prostate-specific antigen (PSA) level/biochemical progression 12-16 weeks after enzalutamide therapy start was significantly associated with metastatic castration-resistant prostate cancer without HRR mutations (р <0.05). In case of tumor response to enzalutamide therapy, decrease in PSA level did not depend on the age of disease onset, differentiation grade, primary advancement, previous docetaxel treatment, and presence of HRR mutation. Cox multivariate regression test showed that prescription of docetaxel before enzalutamide increased the risk of PSA-progression (hazard ratio (HR) 5.160; 95 % confidence interval (CI) 1.549-17.189; р = 0.008) and radiographic progression (HR 5.161; 95 % CI 1.550-17.187; р = 0.008). Progression risk decreased with increased level of PSA decrease 12-16 weeks after enzalutamide therapy start: for PSA decrease >30 % HR 0.150; 95 % CI 0.040-0.570; р = 0.005; for PSA decrease >50 % HR 0.039; 95 % CI 0.006-0.280; р = 0.001; for PSA decrease >90 % HR 0.116; 95 % CI 0.036-0.375; р = 0.000. Presence of HRR mutation, age <58 years, primary metastatic disease and poorly differentiated morphology did not affect duration without PSA-progression (p >0.05). Kaplan-Meier curves showed a trend towards increased time to development of castration resistance in the group of primary early cancer (Breslow р = 0.06; Tarone-Ware р = 0.062). Subgroup analysis showed that in the cohort of patients with castration-resistant prostate cancer (n = 48), absence of HRR mutation in patients who previously received docetaxel therapy increases time to PSA-progression compared to patients with mutations (log-rank р <0.05).

Abstract 4648: How inherited mutations affect single cells within the tumor microenvironment in breast tumors stratified by receptor status

Abstract The tumor microenvironment (TME) plays important roles in tumor progression, therapy response and patient survival. In this comprehensive study, we performed a detailed multiomic single cell analysis of breast cancers with inherited mutations in different genes (BRCA1, BRCA2, PALB2, ATM, CHEK2), and wild type mutation negative (WT) patients, stratified by hormone receptor status, to understand the relationship between inherited mutation and immunogenicity. Using spatial tissue multiplexing (PhenoCycler), single cell RNAseq (10X Genomics) and bulk RNAseq, we evaluated cellular markers within the TME associated with DNA damage as well as phenotypes with tumor suppressive (M1, CD8 T cells, NK cells) or tumor promotive (M2, Treg, CAF) properties. We developed a 43-plex antibody panel and characterized eight tissue microarrays containing 443 patient samples from mutation carriers (BRCA1: n=142, BRCA2: n=118, CHEK2: n=2, TP53: n=3, PALB2: n=7) and WT tumors (n=171). We addressed how the TME differs in mutation carriers versus WT tumors stratified by receptor status. To further investigate immune cell function (cytolytic function, exhaustion, immune checkpoint) as well as pathways involved in immune suppression and/or promotion, we performed scRNA sequencing using isolated single cells from fresh collected BC samples (WT ER: n=3, BRCA2 ER: n=1, CHEK2 ER: n=1, VUS ER: n=1) and bulk RNA (BRCA1: n=17, BRCA2: n=9). To determine immune cell (IC) frequency, we analyzed CD45+ cells detectable in each cohort and their co-expression of markers to determine specific phenotypes. Our data suggest that within BRCA mutation-associated BC, there are two groups: 1) with increased tumor infiltrating lymphocytes (TILs) including CD8+ cytotoxic T cells with high cytolytic function; and 2) with decreased TILs and cytolytic function. The frequency of CD8+ T cells is significantly decreased in breast cancers with BRCA2 mutations compared to BRCA1. Characterizing ER+ CHEK2 BC reveals T cell exhaustion compared to WT ER+ BC. Furthermore, preliminary scRNA results reveal increased fibroblast markers in ER+ CHEK2 and ER+ WT compared to ER+ BRCA2 tumors. Interestingly, cancer associated fibroblast (CAFs) markers (ACTA2, COL1A1, FAP, PDGFRA, PDGFRB, PDPN, THY1) as well as TAMs (CCL2, CD163, CD206, CD68, IL10, LOX, PLOD2, SIGLEC1) are increased in ER+ CHEK2 tumors compared to ER+ WT. These data could provide insights into how the TME associated with ER+ CHEK2 mutations might be driven by CAFs and TAMs with a frequency much higher than in ER+ WT. The detection of immune suppressive (Treg, M2) and immune promotive (M1) phenotypes differs in BRCA1 compared to BRCA2 mutated and WT TNBC. Our findings could decipher the role of DNA repair gene mutations and their effect on cells within the TME that might influence the design of treatment options in patients with inherited mutations based on their receptor status. Citation Format: Dana Pueschl, Derek A. Oldridge, Jonathan Belman, William Chandler, Anupma Nayak, Bradley Wubbenhorst, John Pluta, Michael Feldman, E. John Wherry, Heather Thorne, Georgia Chenevix-Trench, Kathleen Cuningham Foundation Consortium for Resea kConFab, Susan M. Domchek, Katherine L. Nathanson. How inherited mutations affect single cells within the tumor microenvironment in breast tumors stratified by receptor status. [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 4648.

Impact of an Expanded Definition of Family History on Outcomes of Active Surveillance for Prostate Cancer.

Despite family history being an established risk factor for prostate cancer, the role of a broader definition of family history inclusive of not just prostate cancer but other genetically related malignancies has not been investigated in the active surveillance population. Here, we evaluate the impact of an expanded definition of family history on active surveillance outcomes. Patients undergoing active surveillance for prostate cancer at Massachusetts General Hospital from 1997-2019 with detailed data available on family cancer history were identified. Primary outcome was biopsy progression-free survival, and secondary outcomes were treatment-free survival, adverse pathological features at prostatectomy, and biochemical recurrence after treatment. Statistical analyses were conducted using the Kaplan-Meier method and Cox regression. Among 855 evaluable patients, 300 (35.1%) patients had any family history of prostate cancer, and 95 (11.1%) had a family history of related malignancies suggestive of a hereditary cancer syndrome. Family history of prostate cancer alone was not associated with biopsy progression, whereas family history suggestive of a hereditary cancer syndrome was associated with a significantly increased risk of biopsy progression (HR 1.43, 95%CI 1.01-2.02), independent of other known clinicopathological risk factors in multivariable analysis. Similarly, family history suggestive of a hereditary cancer syndrome was associated with significantly lower treatment-free survival (HR 1.58, 95%CI 1.14-2.18) in multivariable analysis. No significant association was found between family history and adverse features on surgical pathology or biochemical recurrence. An expanded family history suggestive of a hereditary cancer syndrome is an independent predictor of biopsy progression during active surveillance. Men with such a family history may still be offered active surveillance but should be counseled regarding the higher risk of disease progression.

Abstract P5-12-05: Gestation and breast cancer in women with mutations in DNA repair genes: Is there any relationship?

Abstract Introduction: Women carrying mutations in reparative genes frequently ask about the safety of pregnancy or the use of fertility-promoting techniques. The evidence on gestation and breast cancer (BC), specifically in mutated BRCA, provides contradictory results1,3. On the one hand, there are studies that support the protective nature of pregnancy, while others show that gestation is a factor that promotes it1. Likewise, some point to differences in the association according to the type of mutation, BRCA1 or BRCA22. Objectives: To prove whether there is a relationship between pregnancy and BC in patients with mutations in DNA repair genes and to establish a solid knowledge base for counseling these patients in clinical practice. Patients and methods: We conducted an analytical, observational and retrospective study of 259 women with mutations in DNA repair genes, whether they had developed cancer or not, with different gestational histories in the Medical Oncology Service. The genes studied were: BRCA1and2, MUTYH, hMSH2, hMSH6,RAD51C,APC,CHECK2,ATM,PALB2,PTEN,BRIP1,ATM+RAD51D,BRCA1+NTHL1,CDKN2A,TP53,NF1,RAD51D. Results: The proportion of patients who develop cancer in the pregnant group is 46.9%. pregnant women is 46.9%, compared to 37.3% in nulliparous women ((χ²) =1.839, p= 0.171). We observed that the diagnosis of BC occurred before the age of 40 years in 40% of pregnant women, compared to 30% in nulliparous women. Likewise, we observed that from the third pregnancy onwards, the percentage of women suffering from BC is higher, with a peak in the fourth pregnancy (68.8% vs. 31.3%) (p=0.135) and that 51.3% of women whose first pregnancy was before the age of 30 years developed BC, compared to 38.6% in those whose first pregnancy was at a later age (X2=4.16, p=0.041). Finally, we observed that 80% of breast cancers developed after 10 years from the first birth. Conclusions: Considering our results, we cannot affirm that at present there is an association between gestation and BC in women with mutation in genes involved in DNA repair. Table: Cross table between cancer (Yes/No) and pregnancy (Yes/No) Citation Format: María López-herrero lópez, Cristina Morales Estévez, Ana Armenta Triviño, Maria Jose Contreras, Maria Gómez Aguilera, Beatriz Rodriguez Alonso, Ignacio Porras, Juan de la Haba-Rodríguez, Enrique Aranda Aguilar. Gestation and breast cancer in women with mutations in DNA repair genes: Is there any relationship? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-12-05.

Internet-Based Germline Genetic Testing for Men With Metastatic Prostate Cancer.

Germline mutations in DNA repair genes are present in approximately 10% of men with metastatic prostate cancer (mPC), and guidelines recommend genetic germline testing. Notable barriers exist, including access to genetic counseling, insurance coverage, and out-of-pocket costs. The GENTleMEN study was designed to determine the feasibility of an Internet-based, patient-driven germline genetic testing approach for men with mPC. In this prospective cohort study, men with mPC provided informed consent via an Internet-based platform and completed a questionnaire including demographics and family cancer history. Supporting medical data were also collected. Genetic testing was performed using the Color Genomics 30-gene targeted panel of cancer predisposition genes on a mailed saliva sample. Men whose test results identified a germline pathogenic or likely pathogenic variant received results by phone or telehealth genetic counseling; other participants received results by email with an option for phone-based or telehealth genetic counseling. As of August 18, 2021, 816 eligible men were consented, of whom 68% (551) completed genetic testing, and 8.7% (48 of 551) were found to carry a pathogenic or likely pathogenic variant in a germline DNA repair gene: CHEK2 (17), BRCA2 (15), ATM (6), NBN1 (3), BRCA1 (2), PALB2 (2), PMS2 (2), and MSH6 (1). Participants were more likely to complete the testing process if they were non-Hispanic White, married, highly educated, or from a higher-income bracket. Here, we show the feasibility of delivering germline (inherited) genetic testing by a voluntary, patient-driven, Internet-based platform to men with mPC. Preliminary results show rates of germline DNA repair mutations, consistent with other cohorts. Although feasible for some, reduced steps for participation, more dedicated diverse outreach and participant support, and identification and addressing of additional barriers is needed to ensure equitable access and optimization.

DNA Damage and Its Role in Cancer Therapeutics.

DNA damage is a double-edged sword in cancer cells. On the one hand, DNA damage exacerbates gene mutation frequency and cancer risk. Mutations in key DNA repair genes, such as breast cancer 1 (BRCA1) and/or breast cancer 2 (BRCA2), induce genomic instability and promote tumorigenesis. On the other hand, the induction of DNA damage using chemical reagents or radiation kills cancer cells effectively. Cancer-burdening mutations in key DNA repair-related genes imply relatively high sensitivity to chemotherapy or radiotherapy because of reduced DNA repair efficiency. Therefore, designing specific inhibitors targeting key enzymes in the DNA repair pathway is an effective way to induce synthetic lethality with chemotherapy or radiotherapy in cancer therapeutics. This study reviews the general pathways involved in DNA repair in cancer cells and the potential proteins that could be targeted for cancer therapeutics.