RAD51C Mutations Research Articles

Mutation Spectrum Comparison between Benign Breast Lesion Cohort, Unselected Cancer Cohort and High-Risk Breast Cancer Cohort.

Mutation study for high-risk breast and ovarian cancer (HBOC) has been extensively studied in patients of different ethnicities. Here we compared the germline mutation rate and mutation spectrum of patients (n = 4341) with benign breast diseases or breast cancers, with and without other risk factors. Three cohorts of Chinese patients were recruited. The first cohort, high-risk cohort (HR, n = 3935) included high-risk breast cancer patients fulfilling high-risk HBOC criteria and who are recruited at our genetics clinic. The second cohort, unselected cancer cohort (CC, n = 307) was from general recruitment of patients with breast cancer at breast surgery clinics. The third cohort, benign breast lesion cohort (NC, n = 99) comprised 99 patients with benign breast diseases such as fibroadenoma, fibroadenomatoid hyperplasia, and intraductal papilloma. Thirty HBOC related genes were sequenced on the above-mentioned patient cohorts. The germline mutation rates of HR, CC, and NC cohort were 11.9%, 6.5%, and 8.1%, respectively. In the CC cohort, 29.3% (90/307) of patients fulfilled the National Comprehensive Cancer Network (NCCN) high-risk genetic test criteria 2022 v.2. The mutation rate for this group of patients was 11.1%, similar to that of the HR cohort, while the mutation rate for those not fulfilling testing criteria was 4.6%, like that of the NC cohort. High penetrance genes (BRCA1/2, CDH1, PALB2, PTEN, and TP53) mutations were only found in the HR (10.6%) and CC (3.3%) cohorts but were not found in the NC cohort. ATM, BRIP1, RAD51C, and RAD51D mutations were identified in all cohorts. RAD51C and RAD51D mutations showed conflicting penetrance. An unexpectedly high mutation rate of total 2% was found in the NC cohort but it was only 0.3% and 0.5% in the HR cohort and CC cohort, respectively. Our results show a clinical need to enhance genetic testing of unselected breast cancer patients to identify the high-risk patients.

Germline RAD51C and RAD51D Mutations in High-Risk Chinese Breast and/or Ovarian Cancer Patients and Families.

RAD51C and RAD51D are crucial in homologous recombination (HR) DNA repair. The prevalence of the RAD51C and RAD51D mutations in breast cancer varies across ethnic groups. Associations of RAD51C and RAD51D germline pathogenic variants (GPVs) with breast and ovarian cancer predisposition have been recently reported and are of interest. We performed multi-gene panel sequencing to study the prevalence of RAD51C and RAD51D germline mutations among 3728 patients with hereditary breast and/or ovarian cancer (HBOC). We identified 18 pathogenic RAD51C and RAD51D mutation carriers, with a mutation frequency of 0.13% (5/3728) and 0.35% (13/3728), respectively. The most common recurrent mutation was RAD51D c.270_271dupTA; p.(Lys91Ilefs*13), with a mutation frequency of 0.30% (11/3728), which was also commonly identified in Asians. Only four out of six cases (66.7%) of this common mutation tested positive for homologous recombination deficiency (HRD). Taking the family studies in our registry and tumor molecular pathology together, we concluded that this relatively common RAD51D variant showed incomplete penetrance in our local Chinese community. Personalized genetic counseling emphasizing family history for families with this variant, as suggested at the UK Cancer Genetics Group (UKCGG) Consensus meeting, would also be appropriate in Chinese families.

Molecular alterations and prognosis of breast cancer with cutaneous metastasis

PurposeCutaneous metastasis (CM) accounts for 5–30% of patients with breast cancer (BC) and presents unfavorable response to treatment and poor prognosis. A better understanding of the molecular alterations involved in metastasis is essential, which would help identify diagnostic and efficacy biomarkers for CM.Materials: We retrospectively reviewed a total of 13 patients with histological or cytological diagnosis of breast cancer and CM. Clinical information was extracted from the medical records. The mutational landscape of matched primary tumors with their lymph nodes or CM tissues were analyzed using next-generation sequencing (NGS) of 425 cancer-relevant genes. All tissues were also analyzed by immunohistochemistry (IHC). The association of prognosis with various clinical and molecular factors was also evaluated.ResultsMore than half of the patients were Ki67 low (< 50%, 53.7%). Most patients (12, 92.3%) had other metastasis sites other than skin. The median time from diagnosis to the presentation of CM (T1) was 15 months (range: 0–94 months) and the median time from CM to death (T2) was 13 months (range 1–78). The most frequently altered genes across the three types of tissues were TP53 (69.6%, 16/23), PIK3CA (34.8%, 8/23), and MYC (26.1%). The number of alterations in CM tends to be higher than in primary tumors (median 8 vs. 6, P = 0.077). Copy number loss in STK11, copy number gain in FGFR4, TERT, AR, FLT4 and VEGFA and mutations in ATRX, SRC, AMER1 and RAD51C were significantly enriched in CM (all P < 0.05). Ki67 high group (> 50%) showed significantly shorter T1 than the Ki67 low group (≤ 50%) (median 12.5 vs. 50.0 months, P = 0.036). TP53, PIK3CA mutations, and TERT amplification group were associated with inferior T2 (median 11 vs. 36 months, P = 0.065; 8 vs. 36 months, P = 0.013, 7 vs. 36 months, P = 0.003, respectively). All p values were not adjusted.ConclusionWe compared the genomic features of primary breast cancer tissues with their corresponding CM tissues and discussed potential genes and pathways that may contribute to the skin metastasis of advanced breast cancers patients. TP53, PIK3CA mutant, and TERT amplification may serve as biomarkers for poor prognosis for CM patients.

Abstract CT042: NCI10217: Phase Ib biomarker-driven tumor-agnostic combination (Combo) trial of copanlisib (Copa) and olaparib (Ola) in molecularly-selected patients (pts) with advanced cancers with PIK3CA hotspot, PTEN and DNA damage response (DDR) mutations

Abstract Background: Preclinically, PI3K and PARP inhibition synergize in cancers with DDR and PI3K pathway alterations. NCI10217 assessed the combo of Copa (pan-PI3K inhibitor) and Ola (PARP inhibitor) in tumors harboring mutations in PI3K/AKT or DDR pathways. Materials and Methods: Eligible pts had tumors with pathogenic PIK3CA hotspot, PTEN and DDR mutations. Copa was administered at 45 mg to 60 mg IV on Days (D) 1 and 15 or 1, 8 and 15 with Ola at 200 mg to 300 mg twice daily (BID) orally in 28-days cycles. Prior PARP and PI3K inhibitors were permitted. Fresh tumor biopsies and ctDNA were mandated at baseline and C1D15 and optional at the end of trial. Study objectives were safety, RP2D, pharmacokinetics, antitumor activity and translational analyses of serial tumor (WES; RNA-Seq; RPPA) and ctDNA samples. Results: 28 pts (M:F 8:20; ECOG PS 0:1 9:19; mean age 58y (28-76y) with breast (n=6), colorectal (n=5), prostate (n=4), endometrial (n=2), gastric (n=2), vaginal (n=2), appendix, cervix, head and neck, leiomyosarcoma, ovarian, peritoneal, and renal (n=1) cancers were enrolled. Pts with BRCA1/2 (n=12), PTEN (n=10), PIK3CA hotspot (n=6), ARID1A (n=4), CHEK2 (n=3), PALB2 (n=3), ATM (n=2), CDK12, CHEK1, MRE11A, RAD51C (n=1 each) mutations were enrolled. 10 pt tumors harbored &amp;gt;1 qualifying mutation. 17 (61%)/28 pts had ≥3 prior lines of therapy; 2 (7%)/28 had prior PARP inhibitors and 1 (4%)/28 had prior PI3K inhibitor. Common treatment-related toxicities included G1/2 mucositis (43%), nausea (43%), diarrhea (36%), anorexia (29%), fatigue (29%), maculo-papular rash (29%), hyperglycemia (25%), vomiting (25%); G3 transient hypertension (29%). Dose-limiting toxicities occurred in 3 (11%)/28 pts: 1 pt (G3 elevated transaminases) at Copa 45 mg (D1, D8 and D15) + Ola 200 mg BID, and 2 pts (G2 mucositis and maculo-papular rash, and G4 hyperglycemia) at Copa 60 mg (D1, D8, and D15) + Ola 300 mg BID. Of 22 pts evaluable for RECISTv1.1 criteria, 6 (27%)/22 pts achieved RECISTv1.1 partial responses (PR): 2 pts with BRCA1 mutation breast cancer; 1 pt with PIK3CA + PTEN + ARID1A mutation breast cancer; 1 pt with PTEN + PALB2 mutation breast cancer and prior PARP inhibitor exposure; 1 pt with BRCA2 mutation prostate cancer; 1 pt with BRCA2 + PTEN mutation prostate cancer. 8 (36%)/22 pts achieved RECISTv1.1 stable disease (SD); 2 (25%)/8 pts had SD≥6 months, including a pt with CA125 response (&amp;gt;50% reduction). Clinical benefit rate (SD≥6 months + PR) was 36%. Responses were deep (up to -100%) and durable (up to 37+ months). Based on these data, the RP2D was established at Copa 60 mg D1 and D15 + Ola 300 mg BID. Conclusion: Copa + Ola was safe and well-tolerated with clinical benefit observed in 36% of pts with advanced cancers with PIK3CA hotspot, PTEN and/or DDR mutations. Translational analyses are ongoing. Citation Format: Timothy A. Yap, Ecaterina E. Dumbrava, Jordi Rodon Ahnert, Apostolia M. Tsimberidou, David Hong, Sarina A. Piha-Paul, Daniel D. Karp, Siqing Fu, Aung Naing, Paula Pohlmann, Jessica R. Rhudy, Sheila B. Berenji-Jalaei, Ashley A. Cole, Christian Valladolid, Desirae Dufner, Bruno B. Bockorny, Andrea Bullock, Daniel Fein, Elizabeth Buchbinder, Atish Choudhury, Candace Haddox, Elizabeth Lee, Gerburg Wulf, Percy Ivy, Rabih Said, Geoffrey Shapiro, Funda Meric-Bernstam. NCI10217: Phase Ib biomarker-driven tumor-agnostic combination (Combo) trial of copanlisib (Copa) and olaparib (Ola) in molecularly-selected patients (pts) with advanced cancers with PIK3CA hotspot, PTEN and DNA damage response (DDR) mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT042.

Abstract 3909: PARG inhibitor sensitivity is correlated with accumulation of single strand DNA gaps in preclinical models of ovarian cancer

Abstract Poly (ADP-ribose) glycohydrolase (PARG) is a dePARylating enzyme which promotes DNA repair in conjunction with PARP1 by removal of poly (ADP-ribose) (PAR). Loss or inhibition of PARG results in replication stress and sensitizes cancer cells to DNA damaging agents, suggesting it is a potential therapeutic target for cancer therapy. Indeed, PARG inhibitors are now undergoing clinical development for patients having tumors with homologous recombination deficiency (HRD), such as ovarian and breast cancer patients with BRCA1/2-mutation. In this study, we investigated PARG inhibitor (PARGi)-PDD00017273 activity in preclinical models of ovarian cancer cell lines and primary patient-derived organoids. PARGi exhibited sensitivity in a subset of ovarian cancer cell lines that was distinct from PARP inhibitor sensitivity. Initially, we evaluated a PARGi-sensitive cell line, RMUGS. By gradually increasing the concentration of PARGi, we generated drug resistant cells. PARGi treatment resulted in increased S phase specific PAR, DNA-PARylation, DNA damage, and replication stress in the sensitive cells but not in cells with de novo or acquired resistance. In the sensitive cells, PARGi exposure also increased accumulation of PAR at the replication fork resulting from unligated Okazaki fragment processing. More importantly, PARGi treatment or PARG loss caused accumulation of single strand DNA (ssDNA) gaps in sensitive cells, as detected by the DNA fiber assays combined with S1 nuclease treatment. Regardless of the BRCA-status, the induction of ssDNA gaps in ovarian cancer cells correlated with PARGi sensitivity. Consistent with an increase in ssDNA gaps, PARGi exposure increased p-RPA, a ssDNA surrogate, at the replication fork in sensitive cells. p-RPA sites also colocalized with PAR suggesting that accumulation of PAR occurs at the ssDNA sites, perhaps, leading to the ssDNA gaps. Collectively, these results suggested that toxic accumulation of PAR at the replication fork leads to accumulation of ssDNA gaps due to Okazaki fragment processing defects and ovarian cancer cell killing after PARG inhibition. We further assessed PARG inhibition in patient-derived organoids (PDOs) and patient-derived xenograft (PDX)-derived organoids (PDXOs) as model systems of ovarian cancer. PARGi exhibited monotherapy activity in specific HR-deficient PDOs and PDXOs with BRCA1 or RAD51C mutation and in a HR-proficient PDXO model. Importantly, PARGi exposure resulted in accumulation of ssDNA gaps in organoids of ovarian cancer and this phenotype directly correlated with drug sensitivity. PDOs can therefore be a useful model system for testing PARGi sensitivity. The detection of ssDNA gaps in PDOs may provide a functional biomarker to predict the response to PARG inhibitors in clinical trials. Citation Format: Ramya Ravindranathan, Ozge Somuncu, Yuqing Jiao, Alexandre André B A da Costa, Benjamin P Lamarre, David B Martignetti, Gabriella A Zambrano, Sirisha Mukkavalli, Joyce Liu, Bose Kochupurakkal, Jean-Bernard Lazaro, Kalindi Parmar, Geoffrey I Shapiro, Alan D. D'Andrea. PARG inhibitor sensitivity is correlated with accumulation of single strand DNA gaps in preclinical models of ovarian 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 3909.

Primary fallopian tube cancer followed by primary breast cancer in RAD51C mutation carrier treated with niraparib as first line maintenance therapy: a case report

Given the rarity of RAD51C mutations, the risk and treatment of metachronous breast cancer after the diagnosis of ovarian cancer in RAD51C mutation carriers is not clear, especially for those who have received PARPi treatment. We report the case of a 65-year-old woman diagnosed with stage IIIC high-grade serous primary fallopian tube cancer. The patient had no family history of breast or ovarian cancer. The patient received three cycles of neoadjuvant chemotherapy with paclitaxel and carboplatin and achieved a complete response. After interval debulking surgery, the patient received three cycles of adjuvant chemotherapy. Collection and extraction of saliva DNA for next-generation sequencing identified a RAD51C mutation c.838-2 A > G. The patient received niraparib as front-line maintenance treatment. After 36 months of niraparib treatment, the patient had grade II invasive ductal carcinoma of the left breast that was positive for estrogen receptor (90%) and Ki-67 (30%) and negative for progesterone receptor and human epidermal growth factor receptor 2. Computed tomography revealed the absence of distant metastases. Modified radical mastectomy and axillary lymph node dissection were then performed. The final pathological report of the breast showed a 1.8 cm Bloom-Richardson grade II invasive ductal carcinoma in the left breast with axillary lymph node metastasis (1/21). Finally, the breast cancer was stage IIA, pT1cN1M0. The metachronous breast cancer in this case may be the first report of second primary cancer in fallopian tube cancer patient harboring a RAD51C mutation during niraparib treatment. Further studies are required to determine optimal treatment.

RAD51C-XRCC3 structure and cancer patient mutations define DNA replication roles

RAD51C is an enigmatic predisposition gene for breast, ovarian, and prostate cancer. Currently, missing structural and related functional understanding limits patient mutation interpretation to homology-directed repair (HDR) function analysis. Here we report the RAD51C-XRCC3 (CX3) X-ray co-crystal structure with bound ATP analog and define separable RAD51C replication stability roles informed by its three-dimensional structure, assembly, and unappreciated polymerization motif. Mapping of cancer patient mutations as a functional guide confirms ATP-binding matching RAD51 recombinase, yet highlights distinct CX3 interfaces. Analyses of CRISPR/Cas9-edited human cells with RAD51C mutations combined with single-molecule, single-cell and biophysics measurements uncover discrete CX3 regions for DNA replication fork protection, restart and reversal, accomplished by separable functions in DNA binding and implied 5’ RAD51 filament capping. Collective findings establish CX3 as a cancer-relevant replication stress response complex, show how HDR-proficient variants could contribute to tumor development, and identify regions to aid functional testing and classification of cancer mutations.

Secretory breast cancer in a boy: A case report with genetic analysis using next-generation sequencing and literature review

Rationale: Male secretory breast cancer is a rare, low-grade carcinoma, especially in boys. Due to its rarity, not much is known about this disease. Patient concerns: A 5-year-old boy presented with a 1.4 cm painless mass in the right breast. Diagnoses: Ultrasonography could not distinguish whether the breast tumor was benign or malignant. After a biopsy of the lumpectomy specimen, it was diagnosed to be secretory breast carcinoma. Interventions: The patient underwent a modified radical mastectomy for his right breast. No postoperative chemotherapy or radiotherapy was performed. Next-generation sequencing of 211 cancer-related genes was detected, and the results revealed an ETV6-NTRK3 translocation and a PDGFRB c.2632A &gt; G mutation. None of the most commonly altered molecules in male aggressive breast cancer (such as BRCA1-2, TP53, RAD51C, and RAD51D mutations) has been identified. Outcomes: The patient was still free from local recurrence or metastases at 6-month follow-up. Lessons: The genomic profile of male pediatric SCB is relatively simple, no other known driver genes have been found except for the ETV6-NTRK3 fusion. Our report will improve our understanding of secretory breast cancer.

HGG-01. INFANT-TYPE HEMISPHERIC GLIOMA: NEW MOLECULAR ALTERATIONS AND PRECISION-MEDICINE TREATMENT

Abstract Introduction Infant-type hemispheric glioma, harboring alterations in the receptor tyrosine kinases ALK, ROS1, NTRK and MET, is a new subtype of Pediatric-type diffuse high-grade gliomas in the 2021 WHO classification of CNS tumors. It has important clinical therapeutic value with specialized therapeutic drugs. Here, we presented 3 cases of infant-type hemispheric glioma. Patient1 with EML4-ALK fusion which often appeared in lung cancer, the other 2 patients have new molecular alterations which has not been reported before (Patient2 has both NTRK1-TP53/TP53-NTRK1 fusions and p53 protein showed characteristic cytoplasm positive; Patient3 presented a brand-new ALK-QKI fusion combined with ALK mutation and focal SMARCB1 deletion. All these 3 cases received corresponding targeted therapy and have a good recovery and normal neurologic function till now. Methods Immunohistochemistry. Fluorescent in situ hybridization. Whole-transcriptome sequencing. Results Case 1: 8 months, male, right semiovale center occupation. HISTOPATHOLOGY High-grade neuroepithelial neoplasm. IHC: GFAP (only few cells+), Olig2(-), S100(+), CD56(+), Syn(-), NSE(focal+), NeuN(-), CD34(-), INI-1(+), Ki67(10%+). Characteristic Molecular Information: EML4-ALK fusion. Follow-up: 15 months, alive. Case 2: 3 years, female, insular lobe occupation. HISTOPATHOLOGY Gliosarcoma. IHC: GFAP(partly+), Olig2(partly+), Vimentin(+), P53(cytoplasm+), pan-TRK(+), Ki67(25%+). Reticular fiber staining showed biphasic tissue pattern with reticulin-rich sarcomatous and reticulin-free gliomatous elements. Characteristic Molecular Information: NTRK1-TP53 and TP53-NRTK1 fusion. Follow-up: 27 months, alive. Case 3: 3 years, male, left parietal occipital lobe occupation. HISTOPATHOLOGY GBM and AT/RT. IHC: GFAP(partly+), Olig2(partly+), INI-1(partly-), BRG1(+), SYN(-), CD34(-), BRAF(-), S100(-), CK(-), H3K27M(-), IDH1(-), P53(40%+), ATRX(+), pan-TRK(-), ALK(+), Ki67(30%+). Characteristic Molecular Information: ALK mutation, ALK-QKI fusion, RAD51C mutation and focal SMARCB1(INI-1) deletion. Follow-up: 14 months, alive. Conclusion: Infant-type hemispheric glioma is a special kind of glioma, which is particularly suitable for precision-medicine treatment approaches. Their overall survival is good compared with other three pHGG subtype.

Safety, pharmacokinetics and anti-tumor activity of RP12146, a PARP1/2 inhibitor, in patients with locally advanced or metastatic solid tumors.

3097 Background: RP12146 is an orally bioavailable, potent small-molecule inhibitor of poly (ADP-ribose) polymerase (PARP) 1 and PARP 2. Pre-clinically, RP1246 demonstrated anti-proliferative activity in both BRCA and non- BRCA mutant cancer cell lines of different tumor types as well as in xenograft models. The first-in-human of RP12146 as a single agent is underway to determine the safety, pharmacokinetics and anti-tumor activity. Methods: The phase I/Ib study was designed as two-part study. Phase I was a dose escalation, 3+3 design, MTD determination study and would enroll pts who have tumors which are known to harbour DNA repair deficiencies. Phase Ib is dose expansion at the MTD/ optimal dose and would enroll thirty-six pts (12 pts each of advanced/metastatic ovarian cancer (OC), breast cancer (BC), and castration-resistant Prostate cancer (mCRPC) having a confirmed deleterious HRR mutation. RP12146 was administered orally in a 28-days cycles until disease progression. Safety were the primary outcome and the investigator-assessed ORR, CBR and PFS assessed using RECIST v1.1, are the secondary outcomes. Predictive biomarker analysis included inhibition of PARP enzyme as measured by gH2AX levels in PMBCs. Results: As of 31-Jan-2023, 9 pts in the dose escalation at 3 dose levels (100 mg QD, 200mg BID and 400 mg BID) and 13 pts (with 5 CHEK2, 4 BRCA2, 2 ATM, 1 CDK12, and 1 RAD51C mutations) in dose expansion have been enrolled. No DLTs were reported in dose escalation. The dose of 400mg BID was considered for dose expansion. Out of 22 pts enrolled, 13 pts had PC, 3 pts had OC, and 2 pts had BC. Most of the related AEs reported were mild in severity except one event of Grade 3 anaemia which resolved, and patient continues to be on therapy. None of the pts developed related SAEs or discontinued due to an AE. Eleven patients (50%) in the expansion group continue to be on RP12146 treatment. RP12146 exhibited rapid absorption achieving maximum concentrations in 1 hr, with an elimination half-life of ~ 4 hrs. Out of the 7 efficacy evaluable PC patients, 5pts showed stable disease and 2pts showed progressive disease. Out of 3 OC pts, 2 pts showed stable disease, and one pt had progressive disease. Among two BC pts, one showed stable disease and the other had progressive disease. Overall, out of 16 efficacy evaluable patients, 8 patients (50%) showed stable disease. Conclusions: RP12146 showed a differentiated safety profile so far with limited hematological toxicities reported as compared to the first-generation PARP inhibitors. Updated safety and efficacy data will be provided at the time of presentation. Clinical trial information: NCT05002868 .

Aggressive progression to EGFR tyrosine kinase inhibitors in advanced NSCLC patients: concomitant mutations, prognostic indicator and subsequent management.

EGFR tyrosine kinase (TKIs) are recommend as the first-line treatment for non-small cell lung cancer (NSCLC) patients with EGFR mutation. However, some patients experience aggressive progression withaprogression-free survival (PFS) less than6months on the first-line EGFR TKI therapy. Therefore, our study is to analyze the potential influencing factors including clinical features, biomarkers, concomitant mutations et al. METHODS: A total of 1073 NSCLC patients with EGFR mutation in a multi-center study from January 2019 to December 2021. The datum pathological and molecular characteristics were collected. The area under the receiver operating characteristic (ROC) curve was used to evaluate the predictive effect of Ki-67 on the first-line TKI. The curve of PFS was conducted by Kaplan-Meier method and tested by bilateral log-rank. Cox regression model was used to predict and evaluate PFS of different variables. Chi-square or Fisher analysis was used for correlation between groups. 55 patients who show aggressive progression(PFS ≤6 months) on the first-line TKI therapy were analyzed in this study, while 71 with slow progression (PFS > 6months). Concomitant mutations including AXIN2, P2CG and RAD51C mutations occurred only in the aggressively progressive group (P = 0.029). Correlation between Ki-67 index and the aggressive progression of the first-line TKI therapy was significant statistically different (P < 0.05). In the second-line therapy, the PFS of chemotherapy in combination with other treatments was better than single TKIs in the first ten months. NSCLC harbored EGFR and concomitant mutations (such as AXIN2, PLCG2 and RAD51C), and/or Ki-67 high expression may indicate the aggressive progression to the first-line EGFR-TKI.

Description of a Retrospective Cohort of Epithelial Ovarian Cancer Patients with Brain Metastases: Evaluation of the Role of PARP Inhibitors in this Setting

The incidence of brain metastases (BM) in patients with epithelial ovarian cancer (EOC) is low: 0.3-11%. The onset of BM has been regarded as a late event with limited treatment options and poor prognosis. This retrospective case series aims to explore the current management strategies with particular emphasis on the use of PARP inhibitors and outcomes, as well as identification of other prognostic indicators. A total of 39 ovarian cancer patients with brain metastases were identified from eight cancer centres in the UK. Clinical characteristics, details of management, and survival data were collected. A total of 14/39 had BM as their first site of relapse. The majority (29 patients) received systemic treatments in addition to local radiotherapy (RT)/surgery. Nineteen patients had BRCA mutations (one somatic), one had a RAD51C mutation, and eighteen were BRCA wild type; one was unknown. A total of 14/39 patients received maintenance PARP inhibitors. As is well known, patients who received PARPi had consistently better outcomes. This was no different for those who received PARPi as part of the management of their BM. Platinum sensitivity and receiving more than one modality of therapy (e.g., radiation +/- chemotherapy and PARPi) for BM were also good prognostic indicators. Median PFS/OS for those treated with chemotherapy and either RT or surgery, then PARP inhibitor maintenance, have not been reached after a median of 33 months follow up. As with abdominal relapse, maintenance treatment with PARP inhibitors also has a valuable role in managing BMs in EOC patients.

DNA methylation of the immediate upstream region of BRCA1 major transcription start sites is an independent favorable prognostic factor in patients with high-grade serous ovarian cancer

ObjectiveTo establish a quantitative method to evaluate the DNA methylation level of an immediate upstream region of major BRCA1 transcriptional start sites (TSSs), and to investigate whether methylation of the region is a prognostic factor in high-grade serous ovarian cancer patients after neoadjuvant chemotherapy. MethodsNinety-two FFPE samples of advanced high-grade serous ovarian cancers after neoadjuvant chemotherapy between 2011 and 2018 were used for mutation and methylation analysis. DNA methylation levels were assessed by pyrosequencing and DNA methylation microarray. An association between methylation level (or a mutation) and progression-free survival was assessed by Kaplan-Meier analysis. ResultMajor BRCA1 transcripts and CpG sites immediately upstream of their TSSs were identified, and a pyrosequencing method was developed. BRCA1 methylation, BRCA1/2 mutations, and a RAD51C mutation were detected in 17/79 (21.5%), 17/92 (18.5%), and 1/92 (1.1%) high-grade serious ovarian cancer samples. In univariate analysis, BRCA1 methylation and no residual tumor were associated with progression-free survival (BRCA1 methylation: P = 0.025, no residual tumor: P = 0.0026). Multivariate analysis showed that both BRCA1 methylation (P = 0.038, HR = 0.47, 95% CI: 0.21–0.96) and no residual tumor (P = 0.012, HR = 0.49, 95% CI: 0.28–0.85) were significant favorable prognostic factors. ConclusionA quantitative method to estimate the methylation level of the immediate upstream region of major BRCA1 TSSs was established. Methylation of the region of was an independent favorable prognostic factor in high-grade serous ovarian cancer patients.

PATH-01. Infant-Type Hemispheric Glioma: New Molecular Alterations and Precision-Medicine Treatment

BACKGROUND: Infant-type hemispheric glioma, harboring alterations in the receptor tyrosine kinases ALK, ROS1, NTRK and MET, is a new subtype of Pediatric-type diffuse high-grade gliomas in the 2021 WHO classification of CNS tumors. It has important clinical therapeutic value with specialized therapeutic drugs. Here, we presented 3 cases of infant-type hemispheric glioma. Patient1 with EML4-ALK fusion which often appeared in lung cancer, the other 2 patients have new molecular alterations which has not been reported before (Patient2 has both NTRK1-TP53/TP53-NTRK1 fusions and p53 protein showed characteristic cytoplasm positive; Patient3 presented a brand-new ALK-QKI fusion combined with ALK mutation and focal SMARCB1 deletion. All these 3 cases received corresponding targeted therapy and have a good recovery and normal neurologic function till now.METHOD: Immunohistochemistry, fluorescent in situ hybridization and whole-transcriptome sequencing. RESULTS: Case 18 months, male, right semiovale center occupation. Histopathology: High-grade neuroepithelial neoplasm. IHC: GFAP(only few cells+), Olig2(-), S100(+), CD56(+), Syn(-), NSE(focal+), NeuN(-), CD34(-), INI-1(+), Ki67(10%+). Characteristic Molecular Information: EML4-ALK fusion. Follow-up: 15 months, alive. Case 2: 3 years, female, insular lobe occupation.Histopathology: Gliosarcoma. IHC: GFAP(partly+), Olig2(partly+), Vimentin(+), P53(cytoplasm+), pan-TRK(+), Ki67(25%+). Reticular fiber staining showed biphasic tissue pattern with reticulin-rich sarcomatous and reticulin-free gliomatous elements. Characteristic Molecular Information: NTRK1-TP53 and TP53-NRTK1 fusion. Follow-up: 27 months, alive. Case 3: 3 years, male, left parietal occipital lobe occupation. Histopathology: GBM and AT/RT. IHC: GFAP(partly+), Olig2(partly+), INI-1(partly-), BRG1(+), SYN(-), CD34(-), BRAF(-), S100(-), CK(-), H3K27M(-), IDH1(-), P53(40%+), ATRX(+), pan-TRK(-), ALK(+), Ki67(30%+). Characteristic Molecular Information: ALK mutation, ALK-QKI fusion, RAD51C mutation and focal SMARCB1(INI-1) deletion. Follow-up: 14 months, alive. CONCLUSION: Infant-type hemispheric glioma is a special kind of glioma, which is particularly suitable for precision-medicine treatment approaches. Their overall survival is good compared with other three pHGG subtype.

Clinical insights from the rucaparib access program in Spain: A sub-analysis of long-term responders by GEICO.

e17562 Background: Rucaparib is a PARP inhibitor approved for the treatment of high-grade ovarian cancer (HGOC). Clinical trials have demonstrated its benefit both as maintenance therapy (MTN) for platinum (Pt)-sensitive recurrent HGOC, and as treatment (Tx) in BRCA-mutated relapsed or recurrent HGOC patients. Here we analyze real-world data from the rucaparib early access program (RAP) in Spain with focus in the long-term responder patients (LTR). Methods: A retrospective observational study was performed by GEICO at 22 hospitals in Spain that had treated patients within the RAP. Adult women with HGOC, fallopian tube, or primary peritoneal cancer were included and received rucaparib (600 mg BID) in the MTN, Tx Pt-sensitive or Tx Pt-resistant setting. Patients’ characteristics, medical history, safety, efficacy, and dosing data were collected. In this analysis, long-term response was defined as progression-free survival (PFS) ≥12 months for the MTN group and ≥6 months for the Tx group. LTR were stratified based on the rucaparib indication (MTN/Tx). Results: Between July 2020 and February 2021, 51 patients were recruited: 18 received rucaparib as MTN and 33 as Tx. In the MTN group, 6 patients (33.3%) were LTR, with a median age of 65 years (54-79). Of them, 2 patients (33.2%) harbored BRCA or RAD51C mutations. The median number of prior lines was 3 (2-6), being ≥5 in 33.2%, and 50.0% received prior bevacizumab. ECOG PS was ≤1 in all these patients, 66.6% had measurable disease and 50.0% achieved a partial response to prior Pt-based chemotherapy. In the Tx group, 10 patients (30.3%) were LTR, with a median age of 71 years (47-86). All of them harbored BRCA and/or RAD51C mutations. The median number of prior lines was 6 (2-9), with 60.0% receiving ≥5 prior lines, and 50.0% received prior bevacizumab. Regarding Pt-status, 40.0% of patients were Pt-sensitive and 60.0% were Pt-resistant. The ECOG PS was ≥1 in 30.0% of patients and 60.0% had measurable disease. The median PFS of LTR was not achieved in the MTN group and was 10.9 months (95% CI: 7.0-16.7) in the Tx group. Adverse events (AE) of any grade were reported in 66.6% of LTR within the MTN group and in 100.0% within the Tx group, while AE of grade ≥3 occurred in 16.6% and 50.0%, respectively. Rucaparib dose was reduced in 50.0% of LTR in the MTN group and 80.0% in the Tx group. Discontinuation rate due to rucaparib toxicity was 20.0% in the Tx group and there were no discontinuations due to toxicity in the MTN group. No new safety signals were detected. At present, 3 and 1 patients are still receiving rucaparib as MTN and Tx, respectively. Conclusions: A durable response was achieved in a notable proportion of patients, even despite their unfavorable conditions at treatment initiation (heavily pre-treated patients, partial response or resistance to Pt, or high volume of disease). The safety profile of rucaparib in this real-world setting is consistent with that reported in clinical trials.

Association of recurrent mutations in BRCA1, BRCA2, RAD51C, PALB2, and CHEK2 with the risk of borderline ovarian tumor

BackgroundThere are several genes associated with ovarian cancer risk. Molecular changes in borderline ovarian tumor (BOT) indicate linkage of this disease to type I ovarian tumors (low-grade ovarian carcinomas). This study determined the prevalence and association of mutations in BRCA1, BRCA2, PALB2, RAD51C, and CHEK2 with the risk of BOTs.MethodsThe study group consisted of 102 patients with histologically confirmed BOT and 1743 healthy controls. In addition, 167 cases with ovarian cancer G1 were analyzed. The analyses included genotyping of 21 founder and recurrent mutations localized in 5 genes (BRCA1, BRCA2, PALB2, RAD51C, and CHEK2). The risk for developing BOT and low-grade ovarian cancer, as well as the association of tested mutations with survival, was estimated.ResultsThe CHEK2 missense mutation (c.470T>C) was associated with 2-times increased risk of BOT (OR=2.05, p=0.03), at an earlier age at diagnosis and about 10% worse rate of a 10-year survival. Mutations in BRCA1 and PALB2 were associated with a high risk of ovarian cancer G1 (OR=8.53, p=0.005 and OR=7.03, p=0.03, respectively) and were related to worse all-cause survival for BRCA1 carriers (HR=4.73, 95%CI 1.45–15.43, p=0.01).ConclusionsResults suggest that CHEK2 (c.470T>C) may possibly play a role in the pathogenesis of BOT, but due to the low number of BOT patients, obtained results should be considered as preliminary. Larger more in-depth studies are required.

Germline RAD51B variants confer susceptibility to breast and ovarian cancers deficient in homologous recombination

Pathogenic germline mutations in the RAD51 paralog genes RAD51C and RAD51D, are known to confer susceptibility to ovarian and triple-negative breast cancer. Here, we investigated whether germline loss-of-function variants affecting another RAD51 paralog gene, RAD51B, are also associated with breast and ovarian cancer. Among 3422 consecutively accrued breast and ovarian cancer patients consented to tumor/germline sequencing, the observed carrier frequency of loss-of-function germline RAD51B variants was significantly higher than control cases from the gnomAD population database (0.26% vs 0.09%), with an odds ratio of 2.69 (95% CI: 1.4–5.3). Furthermore, we demonstrate that tumors harboring biallelic RAD51B alteration are deficient in homologous recombination DNA repair deficiency (HRD), as evidenced by analysis of sequencing data and in vitro functional assays. Our findings suggest that RAD51B should be considered as an addition to clinical germline testing panels for breast and ovarian cancer susceptibility.

Characterization of patients with long-term responses to rucaparib treatment in recurrent ovarian cancer

ObjectiveTo describe molecular and clinical characteristics of patients with high-grade recurrent ovarian carcinoma (HGOC) who had long-term responses to the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib. MethodsThis post hoc analysis pooled patients from Study 10 (NCT01482715; Parts 2A and 2B; n = 54) and ARIEL2 (NCT01891344; Parts 1 and 2; n = 491). Patients with investigator-assessed complete or partial response per RECIST were classified based on duration of response (DOR): long (≥1 year), intermediate (6 months to <1 year), or short (<6 months). Next-generation sequencing was used to detect deleterious mutations and loss of heterozygosity (LOH) in tumors. ResultsOverall, 25.3% (138/545) of enrolled patients were responders. Of these, 27.5% (38/138) had long-term responses; 28.3% (39/138) were intermediate- and 34.8% (48/138) were short-term responders. Most of the long-term responders harbored a BRCA1 or BRCA2 (BRCA) mutation (71.1%, 27/38), and BRCA structural variants were most frequent among long-term responders (14.8%; 4/27). Responders with HGOC harboring a BRCA structural variant (n = 5) had significantly longer DOR than patients with other mutation types (n = 81; median not reached vs 0.62 years; HR, 0.21; 95% CI, 0.10–0.43; unadjusted p = 0.014). Among responders with BRCA wild-type HGOC, most long- and intermediate-term responders had high genome-wide LOH: 81.8% (9/11) and 76.9% (10/13), respectively, including 7 with deleterious RAD51C, RAD51D, or CDK12 mutations. ConclusionAmong patients who responded to rucaparib, a substantial proportion achieved responses lasting ≥1 year. These analyses demonstrate the relationship between DOR to PARP inhibitor treatment and molecular characteristics in HGOC, such as presence of reversion-resistant BRCA structural variants.

Acquired RAD51C Promoter Methylation Loss Causes PARP Inhibitor Resistance in High-Grade Serous Ovarian Carcinoma.

In high-grade serous ovarian carcinoma (HGSC), deleterious mutations in DNA repair gene RAD51C are established drivers of defective homologous recombination and are emerging biomarkers of PARP inhibitor (PARPi) sensitivity. RAD51C promoter methylation (meRAD51C) is detected at similar frequencies to mutations, yet its effects on PARPi responses remain unresolved.In this study, three HGSC patient-derived xenograft (PDX) models with methylation at most or all examined CpG sites in the RAD51C promoter show responses to PARPi. Both complete and heterogeneous methylation patterns were associated with RAD51C gene silencing and homologous recombination deficiency (HRD). PDX models lost meRAD51C following treatment with PARPi rucaparib or niraparib, where a single unmethylated copy of RAD51C was sufficient to drive PARPi resistance. Genomic copy number profiling of one of the PDX models using SNP arrays revealed that this resistance was acquired independently in two genetically distinct lineages.In a cohort of 12 patients with RAD51C-methylated HGSC, various patterns of meRAD51C were associated with genomic "scarring," indicative of HRD history, but exhibited no clear correlations with clinical outcome. Differences in methylation stability under treatment pressure were also observed between patients, where one HGSC was found to maintain meRAD51C after six lines of therapy (four platinum-based), whereas another HGSC sample was found to have heterozygous meRAD51C and elevated RAD51C gene expression (relative to homozygous meRAD51C controls) after only neoadjuvant chemotherapy.As meRAD51C loss in a single gene copy was sufficient to cause PARPi resistance in PDX, methylation zygosity should be carefully assessed in previously treated patients when considering PARPi therapy. SIGNIFICANCE: Homozygous RAD51C methylation is a positive predictive biomarker for sensitivity to PARP inhibitors, whereas a single unmethylated gene copy is sufficient to confer resistance.

Molecular and clinical determinants of response and resistance to rucaparib for recurrent ovarian cancer treatment in ARIEL2 (Parts 1 and 2)

ARIEL2 (NCT01891344) is a single-arm, open-label phase 2 study of the PARP inhibitor (PARPi) rucaparib in relapsed high-grade ovarian carcinoma. In this post hoc exploratory biomarker analysis of pre- and post-platinum ARIEL2 samples, RAD51C and RAD51D mutations and high-level BRCA1 promoter methylation predict response to rucaparib, similar to BRCA1/BRCA2 mutations. BRCA1 methylation loss may be a major cross-resistance mechanism to platinum and PARPi. Genomic scars associated with homologous recombination deficiency are irreversible, persisting even as platinum resistance develops, and therefore are predictive of rucaparib response only in platinum-sensitive disease. The RAS, AKT, and cell cycle pathways may be additional modulators of PARPi sensitivity.