Treatment of HRD-positive elderly ovarian cancer patient: a case report

e17556 Background: Homologous recombination and DNA repair are important for genome maintenance. Genetic variations in essential homologous recombination genes, including BRCA1 and BRCA2, results in homologous recombination deficiency (HRD) can be a target for therapeutic strategies of ovarian cancer (OC) including poly (ADP-ribose) polymerase inhibitors (PARPi). Here, we proposed an emerging method based on ADx-GSS algorithm to predict HRD status and explore the correlation between HRD status and first-line maintenance therapy of Olaparib in OC patients or Olaparib maintenance therapy in platinum-sensitive relapsed (PSR) OC patients. Methods: Formalin-fixed, paraffin-embedded tissues of 38 consented OC patients between January 2016 and March 2021 were retrospectively collected. Genomic DNA was extracted and subjected to AmoyDx HRD Focus Panel (Amoy Diagnostics Co., Ltd) covering HRD score and BRCA1/2. The HRD score was calculated as the weighted sum of different types of copy number variation (CNV) trained through BRCAness events. Tumors were defined as genomic instability with an HRD score of ≥ 50 (i.e. HRD-positive). The primary endpoint was progression-free survival (PFS), and was assessed by Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). Results: Histology of collected samples were mostly serous OC (84.2%). All samples were at stage III-IV (80.84%). The fractions of HRD-positive (n = 26) and HRD-negative (n = 12) group were 68.4%, and 31.6%, respectively. 65.8% (n = 25) of the OC patients had received Olaparib first-line maintenance therapy and 34.2% (n = 13) of PSR patients had received Olaparib maintenance therapy. In December 2021, 34.2% (n = 13) of the whole patients had relapsed. A significant PFS benefit was seen in HRD-positive patients compared with HRD-negative ones (P = 0.0017) or in the first-line maintenance treated population (P = 0.0068). In patients with HRD-positive tumors that did not have BRCA mutations, the PFS benefit was improved versus HRD-negative patients without BRCA mutations. However, Olaparib showed no efficacy difference between HRD-positive and HRD-negative tumor in PSR OC patients. Conclusions: HRD status tested by AmoyDx HRD Focus Panel is significantly correlated with the efficacy of Olaparib, and our results demonstrated a significant PFS benefit for HRD-positive patients compared with HRD-negative patients, especially for patients received Olaparib first-line maintenance therapy.

Patients with high-grade serous ovarian carcinoma (HGSOC) with BRCA1/2 mutations show homologous recombination (HR) deficiency (HRD) and poly (ADP-ribose) polymerase inhibitors (PARPi) sensitivity. Notably, HRD and PARPi response can occur without BRCA mutations, suggesting that other factors are involved. Loss of coiled-coil domain containing 6 (CCDC6) function can lead to HRD and PARPi sensitivity in HGSOC cells, making CCDC6 a potential therapeutic target and biomarker. Three CCDC6 missense mutations in HGSOC prompted an investigation into their impact on HRD. Analyzing CCDC6 expression, localization, and HRD data in the MITO16A trial aims to clarify the CCDC6–HRD relationship in a large cohort. The biochemical and morphologic effects of CCDC6 mutants on the native protein were examined using pull-down assays and immunofluorescence. HR-reporter and cell viability assays determined the impact of these mutants on HRD and PARPi sensitivity. The CCDC6 histochemical score and intracellular localization were assessed in MITO16A samples after immunostaining and digitalization. CCDC6-mutated isoforms act as dominant-negative, preventing native CCDC6 nuclear translocation, disrupting RAD51 foci and HR repair, and increasing PARPi sensitivity. In the MITO16A patient sample set, 66 of 185 (35%) showed barely detectable CCDC6 or nuclear exclusion (“CCDC6-inactive”). CCDC6 impairment in these “CCDC6-inactive” samples was associated with HRD in 75% (30/40) of suitable samples analyzed by the RAD51 test and in 52% (34/65) of suitable samples analyzed by genomic HRD testing, even in the presence of wild-type (WT) BRCA1/BRCA2 genes. The association between CCDC6 inactivity and HRD, both at the genomic and functional levels, occurred even in the presence of WT BRCA1/BRCA2 genes, suggesting that CCDC6 may play a crucial role in DNA repair pathways independent of these well-known genes.Significance:In ovarian cancer, inactivation of the CCDC6 protein signals a defect in DNA repair, known as HRD. This finding might expand the pool of patients, including those who are BRCA WT, who can receive PARP inhibitors, significantly broadening access to this targeted, life-extending therapy.

Poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitor first-line maintenance among patients with newly diagnosed advanced ovarian cancer in a real-world database (351)

To investigate the impact of age on the progression-free survival (PFS) and dose modification, discontinuation and adverse events of poly (adenosine diphosphate-ribose) polymerase inhibitor (PARPi) maintenance therapy in homologous recombination-deficient (HRD) ovarian cancer patients. We analyzed 324 patients with advanced stage III-IV epithelial ovarian cancer who had either BRCA mutation or HRD between July 2019 and November 2022. The primary objective was to evaluate the efficacy of PARPis by comparing PFS between patients who received PARPis and those who did not, specifically within 2 age groups: patients aged <60 years and those aged ≥60 years. The secondary objective included evaluating the rates of dose modification, discontinuation, and occurrence of treatment-emergent adverse events in patients who used PARPis. Of the 324 patients, 139 patients (42.9%) were diagnosed at ≥60 years. The use of PARPis resulted in a significant improvement in PFS in both age groups (hazard ratio [HR]=0.37; p<0.01) for patients aged <60 years (HR=0.41; p<0.01) for those aged ≥60 years. The multivariable Cox proportional hazards analysis revealed no significant difference in the PFS benefit between the 2 age groups (HR=0.95; 95% confidence interval [CI]=0.65-1.37; p=0.76). Dose modifications were more frequent in the elderly cohort (63.9% vs. 46.5%; p=0.04). PARPis significantly improved PFS in elderly ovarian cancer patients with BRCA mutations and HRD, with a toxicity profile similar to that of younger patients. Elderly patients benefited from frequent dose modifications without any negative impact on PFS outcomes.

A pilot study of evaluation of a deep-learning-based homologous recombination deficiency assay in korean patients with ovarian high-grade serous carcinoma: Diagnostic performance and clinical implications.

BRCA1 and BRCA2 are key proteins in the repair of double-strand DNA breaks via homologous recombination (HR) repair. Ovarian carcinomas (OC) with BRCA1 and BRCA2 (BRCA) mutations have HR deficiency (HRD) and are characterized by increased platinum sensitivity and response to poly [adenosine diphosphate (ADP)-ribose] polymerase (PARP) inhibitors, resulting in improved overall survival (1-5). PARP inhibitors generate synthetic lethality in BRCA -mutated carcinomas (6-9), but OC without BRCA mutations can also respond to PARP inhibitors, likely secondary to other sources of HRD (10-13). While up to half of high-grade serous ovarian carcinomas may have a defect in HR, we have found that most histologic subtypes of OC also have a proportion of cases with HRD (1,14). The most common cause of HRD in OC is germline and somatic BRCA mutations, found in approximately 15% and 6%, but mutations or epigenetic silencing of other HR repair genes also contribute (10,14,15). Because cancers with defective HR rely on more error-prone DNA repair such as non-homologous end-joining (NHEJ) or alternative end-joining (alt-EJ), HRD can result in characteristic DNA errors and structural alterations. Thus, a BRCA -like genomic signature may serve as a downstream marker of HRD (16-19). However, finding the best means to identify women without BRCA mutations who are most likely to benefit from PARP inhibitor therapy remains a diagnostic challenge and therapeutic need.

&lt;div&gt;Abstract&lt;p&gt;Patients with high-grade serous ovarian carcinoma (HGSOC) with &lt;i&gt;BRCA1/2&lt;/i&gt; mutations show homologous recombination (HR) deficiency (HRD) and poly (ADP-ribose) polymerase inhibitors (PARPi) sensitivity. Notably, HRD and PARPi response can occur without &lt;i&gt;BRCA&lt;/i&gt; mutations, suggesting that other factors are involved. Loss of coiled-coil domain containing 6 (CCDC6) function can lead to HRD and PARPi sensitivity in HGSOC cells, making CCDC6 a potential therapeutic target and biomarker. Three &lt;i&gt;CCDC6&lt;/i&gt; missense mutations in HGSOC prompted an investigation into their impact on HRD. Analyzing CCDC6 expression, localization, and HRD data in the MITO16A trial aims to clarify the CCDC6–HRD relationship in a large cohort. The biochemical and morphologic effects of CCDC6 mutants on the native protein were examined using pull-down assays and immunofluorescence. HR-reporter and cell viability assays determined the impact of these mutants on HRD and PARPi sensitivity. The CCDC6 histochemical score and intracellular localization were assessed in MITO16A samples after immunostaining and digitalization. CCDC6-mutated isoforms act as dominant-negative, preventing native CCDC6 nuclear translocation, disrupting RAD51 foci and HR repair, and increasing PARPi sensitivity. In the MITO16A patient sample set, 66 of 185 (35%) showed barely detectable CCDC6 or nuclear exclusion (“CCDC6-inactive”). CCDC6 impairment in these “CCDC6-inactive” samples was associated with HRD in 75% (30/40) of suitable samples analyzed by the RAD51 test and in 52% (34/65) of suitable samples analyzed by genomic HRD testing, even in the presence of wild-type (WT) &lt;i&gt;BRCA1/BRCA2&lt;/i&gt; genes. The association between CCDC6 inactivity and HRD, both at the genomic and functional levels, occurred even in the presence of WT &lt;i&gt;BRCA1/BRCA2&lt;/i&gt; genes, suggesting that CCDC6 may play a crucial role in DNA repair pathways independent of these well-known genes.&lt;/p&gt;Significance:&lt;p&gt;In ovarian cancer, inactivation of the CCDC6 protein signals a defect in DNA repair, known as HRD. This finding might expand the pool of patients, including those who are &lt;i&gt;BRCA&lt;/i&gt; WT, who can receive PARP inhibitors, significantly broadening access to this targeted, life-extending therapy.&lt;/p&gt;&lt;/div&gt;

e18707 Background: Options for first-line (1L) maintenance therapy in ovarian cancer (OC) have evolved in the US in recent years, particularly with FDA approvals of poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPi). Olaparib was approved in 2018 for 1L maintenance treatment of patients (pts) with advanced OC with BRCA mutation and in 2020 as combination therapy with bevacizumab for 1L maintenance treatment of pts with homologous recombination deficient (HRd)–positive tumors. Additionally, the FDA approved niraparib in 2020 for maintenance treatment of pts with advanced OC regardless of tumor biomarker status. This study aimed to describe use and outcomes of 1L maintenance vs. active surveillance (AS) among PARPi-eligible pts with OC in a real-world setting prior to the most recent 2020 FDA approvals. Methods: This retrospective cohort study included pts with newly diagnosed stage III/IV OC who received 6–9 cycles of 1L platinum-based chemotherapy (PBC) and either primary debulking surgery or interval debulking surgery following neoadjuvant chemotherapy between January 1, 2016, and February 29, 2020, regardless of biomarker status, from the Flatiron Health database, a longitudinal electronic health record-derived database consisting of de-identified patient-level data that are curated via technology-enabled abstraction. The end of the last cycle of 1L PBC was defined as the index date. Pts who started second-line (2L) treatment within 2 months of the index date were excluded. Primary endpoint was time to initiation of 2L systemic therapy (as a surrogate for progression) or death. Inverse probability of treatment weighting and Cox proportional hazard model were used to adjust for baseline differences among pts on maintenance therapy and pts on AS. Results: A total of 463 pts were included in the study, 87.7% from community practices and 12.3% from academic institutions. Of the pts included, 21.0% received maintenance therapy, while 79.0% did not. Of those who received maintenance therapy, 48.5% received bevacizumab, 40.2% received PARPi (olaparib, rucaparib), and 11.3% received paclitaxel. Median progression-free survival (PFS) for pts who received 1L maintenance therapy was 16.1 months, compared with 12.2 months in pts who did not receive 1L maintenance therapy. After adjusting for baseline differences in characteristics and demographics, including age, race, stage of cancer, and BRCA status, pts on maintenance therapy had a statistically significant, 29% lower risk of progression or death than those receiving AS (hazard ratio: 0.71; 95% CI, 0.52–0.99; P= 0.04). Conclusions: In this real-world analysis, the majority of pts did not receive maintenance therapy; however, a PFS benefit was found in those receiving maintenance therapy. Further studies are needed to understand how biomarker status drives practice patterns.

Homologous recombination deficiency (HRD) testing has been approved by FDA for selecting epithelial ovarian cancer (EOC) patients who may benefit from the first-line poly (ADP-ribose) polymerase inhibitor (PARPi) maintenance therapy. However, the effects of HRD on the clinical outcomes of first-line chemotherapy and first-line PARPi maintenance therapy have not been rigorously evaluated in Chinese EOC patients. Here, we developed an HRD assay and applied it to two large retrospectively collected Chinese EOC patient cohorts. In the first-line adjuvant chemotherapy cohort (FACT, N = 380), HRD status significantly improved PFS (median, 15.6 months vs. 9.4 months; HR, 0.688; 95% CI, 0.526–0.899; P = 0.003) and OS (median, 89.5 months vs. 60.9 months; HR, 0.636; 95% CI, 0.423–0.955; P = 0.008). In the first-line PARPi maintenance therapy cohort (FPMT, N = 83), HRD status significantly improved PFS (median, NA vs. 12 months; HR, 0.438; 95% CI, 0.201–0.957; P = 0.033) and OS (median, NA vs. NA months; HR, 0.12; 95% CI, 0.029–0.505; P = 0.001). Our results demonstrate that HRD status is a significant predictor for PFS and OS in both first-line chemotherapy and first-line PARPi maintenance therapy, providing strong real-world evidence for conducting genetic testing and improving clinical recommendations for Chinese EOC patients.

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

Background: Genome-wide analysis was conducted on tumors obtained from patients enrolled in the NOVA study, a Phase 3 clinical trial evaluating the PARP inhibitor niraparib as a maintenance treatment in patients with platinum-sensitive ovarian cancer. Homologous recombination deficiency (HRD) and mutations in DNA damage repair genes were evaluated. Material and methods: DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tumor tissue and used to create libraries that were hybridized to a custom Agilent SureSelect capture array carrying probes for 54,091 single nucleotide polymorphism sites distributed across the human genome, as well as probes targeting 43 genes involved in DNA repair, including BRCA1 and BRCA2. The captured and enriched DNA was sequenced on an Illumina HiSeq 2500 sequencer. Sequences covering SNP positions were used to generate allelic imbalance profiles. Measures of genomic instability, including determination of an HRD score (integer value of 0-100), were calculated using allelic imbalance profiles and determination of loss of heterozygosity (LOH) by allele-specific copy number (ASCN). A previously identified HRD threshold score of 42 was used to define HRD positivity in the absence of a BRCA mutation. Results: The NOVA study is a Phase 3, multicenter, randomized, double-blind, placebo-controlled study of niraparib as maintenance therapy in ovarian cancer patients who have either gBRCAmut or a tumor with high-grade serous histology and who have responded to their most recent chemotherapy containing a platinum agent. Tumor BRCA mutational status, HRD score and genomic sequencing of 43 DNA repair genes were obtained from tumor samples from both gBRCAmut and non-gBRCAmut cohorts. In the gBRCAmut cohort, HRD analysis of the tumor confirmed the presence of a deleterious or suspected deleterious mutation in all cases. In addition, an HRD score ≥ 42 and the presence of a deleterious mutation in TP53 with loss of heterozygosity (LOH) were observed in nearly all tumors. In the non-gBRCA cohort, somatic BRCA mutations were observed in approximately 13% of tumors, and approximately half of tumors with no evidence of a BRCA mutation had a high HRD score. In both cohorts, the use of three scoring algorithms (LOH, telomeric allelic imbalance [TAI], large-scale state transitions [LST]), was more predictive of BRCA mutational status than LOH alone. Additional genomic sequencing identified deleterious mutations with LOH in DNA repair genes, such as BRIP1, CDK12, RAD51C, PTEN, and RAD51D, with many tumors exhibiting multiple deleterious mutations. Conclusions: High grade serous ovarian cancer is characterized by a high degree of genomic instability. Genomic analysis in the clinical setting is able to identify patients with both germline and somatic BRCA mutations, in addition to BRCAwt tumors with other genetic defects that may be sensitive to agents exploiting deficiencies in HR. Citation Format: Keith Wilcoxen, Christopher Neff, Victor Abkevich, Joshua Timothy Jones, Kathryn Kolquist, Michael Mirza, Jerry Lanchbury, Keith Mikule, Shefali Agarwal, Anne-Renee Hartman, Alexander Gutin, Kirsten Timms. Homologous recombination deficiency (HRD) of high grade serous ovarian tumors from the NOVA Phase III clinical study. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C53.

Objective: The real-world clinical data of patients with newly diagnosed ovarian cancer (including fallopian tube cancer and primary peritoneal cancer) who received first-line maintenance therapy with poly adenosine diphosphate ribose polymerase inhibitor (PARPi) were retrospectively analyzed, and the prognostic factors were preliminarily explored. Methods: (1) The clinicopathological data and follow-up data of ovarian cancer patients treated with PARPi first-line maintenance therapy from August 2018 (PARPi was launched in China) to December 31, 2021 in Sichuan Cancer Hospital were collected (real-world clinical data). (2) According to the different types of PARPi, real-world clinical data were divided into olaparib group and niraparib group, which were respectively compared with the inclusion and exclusion criteria of representative domestic and foreign phase Ⅲ randomized controlled trials (RCT), including olaparib as first-line maintenance therapy for advanced ovarian cancer patients with BRCA1/2 gene mutation (SOLO-1 study), niraparib as first-line maintenance therapy (PRIMA study), and niraparib as first-line maintenance therapy for Chinese advanced ovarian cancer patients (PRIME study). (3) The prognosis of the two groups and the prognostic factors were analyzed. Results: (1) A total of 83 patients were included in this study, with a median age of 51 years (47-57 years), including 75 cases of ovarian cancer, 5 cases of fallopian tube cancer, and 3 cases of primary peritoneal cancer; 5 cases of stage Ⅰ, 9 cases of stage Ⅱ, 55 cases of stage Ⅲ, 12 cases of stage Ⅳ, and 2 cases of unknown stage; neoadjuvant chemotherapy (NACT) was performed in 40 cases and non-NACT in 43 cases; 62 cases had no visible residual lesion after surgery (R0), 9 cases had residual disease lesions <1 cm (R1), 8 cases had residual disease lesions ≥1 cm (R2), and 4 cases with unknown postoperative residual disease. Thirty-two cases had PARPi treatment interruption, 40 cases had PARPi reduction, and 1 case terminated treatment due to acute leukemia. Of the 83 patients, 35 were in the olaparib group and 48 were in the niraparib group. The proportion of patients with high-grade serous carcinoma (100% and 75%, respectively) and the proportion of BRCA mutant patients (91% and 10%, respectively) in the olaparib group were higher than those in the niraparib group (all P<0.01). (2) Compared with the inclusion and exclusion criteria of the SOLO-1 study, the olaparib group had only 60% (21/35) coincidence rate; compared with the inclusion and exclusion criteria of PRIMA and PRIME studies, the coincidence rates of niraparib group were only 31% (15/48) and 69% (33/48). The most common reasons for non-compliance were number of chemotherapy courses, histopathological type, and surgical pathological stage. (3) Of the 83 cases received first-line maintenance therapy with PARPi, the median follow-up was 15.9 months (11.3-22.9 months), the median progression-free survival (PFS) was 29.7 months (95%CI: 25.9-33.6 months), and the median overall survival was 49.8 months (95%CI: 47.4-52.2 months). Univariate analysis showed that unilateral or bilateral ovarian cancer, efficacy after platinum-containing chemotherapy, presence or absence of measurable lesions at the end of chemotherapy, and total number of chemotherapy courses were significantly associated with PFS (all P<0.05). Multivariate analysis showed that unilateral or bilateral ovarian cancer, total number of chemotherapy courses, and efficacy after platinum-containing chemotherapy were independent factors affecting PFS in stage Ⅱ-Ⅳ patients with PARPi first-line maintenance therapy (all P<0.05). Conclusions: Unilateral ovarian cancer, the total number of chemotherapy courses no more than 9, and achieving complete response after platinum-containing chemotherapy before maintenance therapy are independent influencing factors of PFS benefit in patients with PARPi first-line maintenance therapy. Due to the large differences between the patients in real clinical practice and the research subjects of phase Ⅲ RCT, the results of representative retrospective studies still have important clinical reference significance.

Standard therapy for advanced ovarian cancer consists of primary surgical debulking followed by 6 cycles of platinum-based chemotherapy and maintenance therapy with bevacizumab and/or poly-ADP ribose polymerase (PARP) inhibitors (PARPi). While homologous recombination deficiency (HRD)-positive patients derive meaningful benefit from PARPi maintenance; HRD-negative patients derive limited benefit, and the toxicity associated with 6 cycles of chemotherapy may negatively affect patients' quality of life, raising the question whether reducing chemotherapy cycles could decrease morbidity without compromising efficacy. To compare recurrence-free survival and overall survival in patients with International Federation of Gynecology and Obstetrics stage III to IV, HRD-positive ovarian cancer who achieve complete debulking, treated with either 3 or 6 cycles of platinum-based chemotherapy, both followed by maintenance therapy with the PARP inhibitor niraparib. We hypothesize that recurrence-free survival in patients receiving 3 cycles of chemotherapy followed by niraparib is non-inferior (defined as a hazard ratio [HR] ≤1.3) to 6 cycles of chemotherapy followed by niraparib, as assessed by a multi-variable Cox regression model. This is a multicenter, randomized, open-label Phase II non-inferiority study. Participants will be randomized 1:1 to either 3 (Arm A) or 6 (Arm B) cycles of platinum-based chemotherapy, both followed by niraparib maintenance for 3 years, at a starting dose of 200 mg once daily or 300 mg once daily depending on patient factors (eg, body weight, platelet count), after complete surgical debulking. The study is currently open for recruitment in all participating countries in Europe, further details can be found under at Clinicaltrials.gov ID: NCT05460000. Eligible patients include women with International Federation of Gynecology and Obstetrics stage III to IV high-grade ovarian cancer, confirmed HRD positivity (including pathogenic BRCA mutations) after centralized testing, and no residual disease following primary tumor debulking. The HRD test will be conducted centrally using the validated North-Eastern-German Society of Gynaecologic Oncology-Genomic Instability Score Assay. The primary endpoint is recurrence-free survival. Overall survival, Quality of life, Toxicity, detailed list under "outcomes." 640 patients. Accrual completion is expected in 2032, with results presentation anticipated in 2033. NCT05460000. This trial aims to provide high-quality evidence on whether a reduced number of chemotherapy cycles in the era of niraparib maintenance for 3 years can safely maintain efficacy while minimizing treatment-related toxicity and improving patients' quality of life.

Background: Poly (ADP-ribose) polymerase inhibitors (PARPi) are an important tool for treatment of ovarian and other cancers, particularly for those with mutations in BRCA1 or 2 genes or homologous recombination deficiency. The risk of developing secondary hematologic malignancy, particularly myelodysplastic syndrome or acute myeloid leukemia (MDS/AML), is substantially higher (4-12%) after PARPi maintenance or treatment in the second line and beyond in patients with ovarian cancer. This elevated risk necessitates additional investigation into the pathogenesis of PARPi-related secondary malignancy. Clonal hematopoiesis of indeterminate potential (CHIP) has been associated with the development of therapy-related myeloid neoplasms. We aim to understand the patterns of CHIP in patients with high grade serous ovarian carcinoma who receive PARPi therapy. Methods: We performed ultra-high-depth whole exome sequencing of plasma derived cfDNA or white blood cells (WBCs) barcoded with unique molecular identifiers from patients with high grade serous ovarian carcinoma who were treated with multiple lines of chemotherapy (n=6) or with PARPi in addition to chemotherapy (n = 10). Using spike-in mutated DNAs as positive controls, we detected variant alleles as low as 1% variant allele frequency. Gene set enrichment analysis was performed on identified groups. Results: We identified 7162 recurrent variants among our patients. We began by comparing quantities of CHIP between the samples from patients who eventually receive PARPi and those who do not. Samples contained a median of 2030 recurrent CHIP variants and 4300 total variants. No differences in total CHIP quantity or mutation type was discernable among samples from patients who will receive PARPi (BRCA1/2 enriched) vs those who will not. Among our 16 patients, 14 ultimately developed secondary hematologic malignancy (t-MN+ Comparison of t-MN+ (n=14) and t-MN- (n=2) defined a group of 14 variants enriched in the t-MN+ population and a group of 85 variants depleted in the t-MN+ population. The t-MN+ enriched variants we identified were not previously associated with CHIP and had significant overlaps with alkyl transferase activity (FDR q val &amp;lt; 0.01) and nucleotide binding gene sets (FDR q val &amp;lt; 0.01). Conclusions: We used a novel methodology to identify unbiased low variant mutational changes in the hematopoietic system. These results suggest that baseline clonal hematopoiesis variants are similar among patients newly diagnosed with ovarian carcinoma. We have also identified a signature potentially related to future risk of leukemia requiring further validation. Citation Format: Amma Asare, Sara Corvigno, Jun Yao, Li Zhao, Nicole D. Fleming, Joseph Celestino, Richard A. Hajek, Mark S. Kim, Alejandra Flores Legarreta, Karen H. Lu, Koichi Takahashi, P Andrew Futreal, Amir A. Jazaeri, Shannon N. Westin, Anil K. Sood, Sanghoon Lee. Landscape of clonal hematopoiesis prior to PARP inhibitor treatment in patients with 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 5070.

Introduction/BackgroundNiraparib is the first PARP inhibitor to be approved for the first-line maintenance (1LM) treatment of all patients with newly diagnosed advanced ovarian cancer. The RENI-1 study (NCT04986371) was designed...