N6-methyladenosine-mediated upregulation of LNCAROD confers radioresistance in esophageal squamous cell carcinoma through stabilizing PARP1.

BACKGROUND: Radiotherapy is a primary therapeutic modality for esophageal squamous cell carcinoma (ESCC), but its effectiveness is still restricted due to the resistance of cancer cells to radiation. Long non-coding RNAs (lncRNAs) and N6-methyladenosine (m6A) have been shown to play significant roles in tumour radioresistance. However, the precise manifestation and role of m6A-modified lncRNAs in ESCC radioresistance remain unclear. METHODS: Bioinformatics analysis was conducted to identify m6A-modified lncRNAs implicated in the radioresistance of ESCC. A series of functional experiments were performed to investigate the function of LNCAROD in ESCC. Methylated RNA immunoprecipitation, chromatin isolation by RNA purification-mass spectrometry, RNA immunoprecipitation, and co-immunoprecipitation experiments were performed to explore the mechanism of m6A-mediated upregulation of LNCAROD expression and the downstream mechanism enhancing the radioresistance of ESCC. The efficacy of LNCAROD in vivo was assessed using murine xenograft models. RESULTS: Herein, we identified LNCAROD as a novel METTL3-mediated lncRNA that enhanced radioresistance in ESCC cells and was post-transcriptionally stabilised by YTHDC1. Moreover, we confirmed that LNCAROD prevented ubiquitin-proteasome degradation of PARP1 protein by facilitating PARP1-NPM1 interaction, thereby contributing to homologous recombination-mediated DNA double-strand breaks repair and enhancing the radiation resistance of ESCC cells. Silencing LNCAROD in a nude mouse model of ESCC in vivo resulted in slower tumour growth and increased radiosensitivity. CONCLUSION: Our findings enhance the understanding of m6A-modified lncRNA-driven machinery in ESCC radioresistance and underscore the significance of LNCAROD in this context, thereby contributing to the development of a potential therapeutic target for ESCC patients.

Efficacy and safety of PARP inhibitor maintenance therapy for ovarian cancer: a meta-analysis and trial sequential analysis of randomized controlled trials.

Background: The landscape of poly (ADP-ribose) polymerase (PARP) inhibitor treatment for ovarian cancer (OC) is continually evolving. This research aimed to evaluate the efficacy and safety of PARP inhibitors compared to placebo as a maintenance therapy for OC patients. Methods: We conducted a search of PubMed, Embase, Web of Science, and the Cochrane Library databases for randomized controlled trials (RCTs) involving the use of PARP inhibitors as maintenance therapy in OC patients, up to 16 June 2024. Data regarding progression-free survival (PFS), overall survival (OS), chemotherapy-free interval (CFI), time to first subsequent therapy or death (TFST), time to second subsequent therapy or death (TSST), and treatment-emergent adverse events (TEAEs) were aggregated. Pooled hazard ratio (HR) and their corresponding 95% confidence intervals (CI) were calculated for PFS, OS, CFI, TFST, and TSST. Additionally, the relative risk (RR) and 95% CI for TEAEs were determined. Results: This meta-analysis encompassed 20 RCTs involving 7,832 participants. The overall analysis demonstrated that maintenance therapy with PARP inhibitors led to significant improvements in PFS (HR: 0.398, 95% CI = 0.339-0.467, 95% PI = 0.219-0.724), OS (HR: 0.677, 95% CI = 0.582-0.788, 95% PI = 0.546-0.839), CFI (HR: 0.417, 95% CI = 0.368-0.472, 95% PI = 0.265-0.627), TFST (HR: 0.441, 95% CI = 0.391-0.498, 95% PI = 0.308-0.632), and TSST (HR: 0.574, 95% CI = 0.507-0.649, 95% PI = 0.488-0.674) compared with placebo. Subgroup analyses further indicated that PARP inhibitor maintenance treatment significantly improved PFS, regardless of homologous recombination status (all p < 0.05). However, the risks of any grade (RR = 1.046, 95% CI = 1.032-1.059, 95% PI = 1.028-1.055) and grade ≥3 TEAEs (RR = 2.931, 95% CI = 2.641-3.253, 95% PI = 2.128-3.792) were increased by PARP inhibitor maintenance therapy compared to placebo. Conclusion: Our research elucidated the benefits of maintenance therapy with PARP inhibitors in patients with OC, showing improvements in PFS, OS, CFI, TFST, and TSST. Vigilance regarding TEAEs is paramount for clinicians implementing PARP inhibitor maintenance therapy in clinical practice. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024560286.

Niraparib Enhances and Synergizes with Ganglioside GD2 to Potentiate its Inhibitory Effect on Bladder Cancer Cells.

PURPOSE: This study aimed to study the inhibitory effect of niraparib alone or in combination with GD2 specific antibody on Bladder Cancer (BCa). METHODS: The migration ability of BCa cells was assessed through a scratch assay. CCK-8 assay was performed to evaluate the viability of BCa cells, and Transwell invasion assays were utilized to examine invasive capacity. The expression levels of E-cadherin and vimentin in BCa cells were measured using QRT-PCR. RESULTS: Western blot showed the EMT level to be the lowest in the niraparib+GD2 group. The transwell invasion assay suggested that the invasion ability of BCa cells was weakened in the niraparib+ GD2 group. CCK8 assay indicated that the proliferation ability of BCa cells was decreased. Scratch test suggested that the migration ability of BCa cells was weakened. PCR result showed that the niraparib + GD2 group had the most significant inhibitory effect on mRNA expression of EMT markers. CONCLUSION: Niraparib combined with a GD2-specific antibody exerted a more prominent inhibitory effect on BCa.

Developing combination therapies with biologics in triple-negative breast cancer.

INTRODUCTION: Novel compounds have entered the triple-negative breast cancer (TNBC) treatment algorithm, namely immune checkpoints inhibitors (ICIs), PARP inhibitors and antibody-drug conjugates (ADCs). The optimization of treatment efficacy can be enhanced with the use of combination treatments, and the incorporation of novel compounds. In this review, we discuss the combination treatments under development for the treatment of TNBC. AREAS COVERED: The development of new drugs occurring in recent years has boosted the research for novel combinations to target TNBC heterogeneity and improve outcomes. ICIs, ADCs, tyrosine kinase inhibitors (TKIs), and PARP inhibitors have emerged as leading players in this new landscape, while other compounds like novel intracellular pathways inhibitors or cancer vaccines are drawing more and more interest. The future of TNBC is outlined in combination approaches, and based on new cancer targets, including many chemotherapy-free treatments. EXPERT OPINION: A large number of TNBC therapies have either proved clinically ineffective or weighted by unacceptable safety profiles. Others, however, have provided promising results and are currently in late-stage clinical trials, while a few have actually changed clinical practice in recent years. As novel, more and more selective drugs come up, combination strategies focusing the concept of synergy are fully warranted for the future.

Poly(Adenosine Diphosphate Ribose) Polymerase (PARP) Inhibitors in the Treatment of Advanced Ovarian Cancer: A Narrative Review.

Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors have appeared as a revolutionary approach to treating advanced ovarian cancer, particularly in patients with breast cancer (BRCA) mutations and homologous recombination deficiency (HRD). This narrative review explores PARP inhibitors' clinical efficiency, safety, and changing role in this context. PARP inhibitors, such as olaparib, niraparib, or rucaparib, provide considerable benefits regarding progression-free survival expansion and overall outcomes improvement in first-line maintenance and recurrent settings. The underlying mechanisms, patient selection criteria, and resistance patterns are discussed, alongside insights into combination therapies to overcome resistance and enhance therapeutic efficacy. Ongoing clinical trials and future potential for personalized therapy approaches using PARP inhibitors for advanced ovarian cancer are also highlighted. However, despite these drugs' phenomenal ability to revolutionize treatment protocols for such cancer types, several challenges remain: toxicity management, cost, and development of resistance will require more research to optimize their use or broaden patient populations who can benefit from them.

Olaparib as maintenance therapy in non resectable pancreatic adenocarcinoma associated with homologous recombination deficiency profile: A French retrospective multicentric AGEO real-world study.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis. The POLO trial showed that olaparib (PARP inhibitor) improved progression-free survival (PFS) but not overall survival (OS), when used as maintenance therapy after ≥ 16 weeks of disease control with first-line platinum-based chemotherapy in patients with germline (g) BRCA 1 or 2 pathogenic variants (PV) metastatic PDAC. However, real-world data on the effectiveness of olaparib are missing. METHODS: Patients with unresectable PDAC associated with somatic (s) or (g)BRCA1/2 and (g)non-BRCA-HRD PV (i.e. other homologous recombination deficiency/HRD genes) who were treated with olaparib between 2020-2023 were included. The primary objective was to describe treatment patterns. Secondary exploratory objectives included OS and PFS in patients treated with olaparib according to the POLO trial or not, OS and PFS in patients with (g)HRD PV-associated PDAC versus (s)PVs, olaparib safety profile and factors associated with olaparib poor outcomes. RESULTS: Among 85 patients, 45.9 % received olaparib as defined by the POLO trial. No difference in OS and PFS was observed between patients who received olaparib according to the POLO trial versus not. Patients with (g)HRD PV-associated PDAC had better OS compared to others (22.3 versus 10.5 months, p = 0.038). Factors associated with olaparib poor outcomes included a high neutrophil-to-lymphocyte ratio and the use of olaparib outside the recommendations of the POLO trial. Few grade ≥ 3 adverse events were reported (9.4 %). CONCLUSION: Patients with (g)HRD PV-associated PDAC had longer OS than those with (s)HRD PV. Olaparib use beyond the scope of the POLO trial was associated with poor outcomes.

Isoxazole compounds: Unveiling the synthetic strategy, in-silico SAR & toxicity studies and future perspective as PARP inhibitor in cancer therapy.

Latest developments in cancer treatment have shed a light on the crucial role of PARP inhibitors that enhance the treatment effectiveness by modifying abnormal repair pathways. PARP inhibitors, such as Olaparib, Rucaparib, Niraparib, and Talazoparib have been approved in a number of cancers including BRCA 1/BRCA2 associated malignancies although there are many difficulties as therapeutical resistance. Besides the conventional synthetic drugs, natural compounds such as flavones and flavonoids have been found to be PARP inhibitors but only in preclinical studies. Isoxazole is very important class of potential candidates for medicinal chemistry with anti-cancer and other pharmacological activities. At present, there are no approved PARP inhibitors of isoxazole origin but their ability to hit many pathways inside the cancer cells points out on its importance for future treatments design. In drug development, isoxazoles are helpful because of the molecular design flexibility that may be enhanced using various synthetic approaches. This review highlights the molecular mechanisms of PARP inhibition, importance of isoxazole compounds and present advances in their synthetic strategies that demonstrate promise for these agents as new anticancer drugs. It emphasizes that isoxazole-based PARP inhibitors compounds could be novel anti-cancer drugs. Through this review, we hope to grow a curiosity in additional explorations of isoxazole-based PARP inhibitors and their applications in the trends of novel insights towards precision cancer therapy.

PARP inhibitors in ovarian cancer: Mechanisms, resistance, and the promise of combination therapy.

Current approaches to treating ovarian cancer focus mainly on surgical cytoreduction and chemotherapy using platinum-based drugs, while newer methods such as immunotherapy are being investigated to enhance treatment outcomes. Treating ovarian cancer is complicated by challenges such as late-stage detection, tumor diversity, and limited treatment choices. Therefore, innovative strategies such as precision medicine and targeted therapies like PARPi (Poly ADP-Ribose Polymerase inhibitors) are increasingly necessary. The article highlights the significance of an innovative therapeutic approach focusing on PARPi in revolutionizing ovarian cancer treatment and improving patient outcomes. It covers the basic knowledge of PARP, its structure, and its function in DNA repair. It further emphasizes how inhibiting PARP can help in treating ovarian cancer. It elaborates on the mechanism of action of PARPi. It covers the clinical trials governing PARPi and the combination of drugs used with PARPi. It mentions how the resistance is developed to PARPi and the strategies to overcome the resistance developed.

Association of PARP1 Expression Levels and Clinical Parameters in Different Leukemic Subtypes With BCR::ABL1 p190+ Translocation.

Background/Aim: Although the reciprocal translocation t(9;22)(q34;q11) is a hallmark of chronic myeloid leukemia (CML), it is also present in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Depending on the gene's breakpoint, it is possible to obtain three isoforms, among which p190 stands out for the poor prognosis it induces whenever it appears. Due to the genomic instability induced by BCR::ABL1, it is proposed to expand the applicability of poly-ADP-ribose polymerase-1 (PARP1) and its inhibitors in hematological neoplasms. Materials and Methods: We measured the expression levels of PARP1 by quantitative real-time PCR (qPCR) using TaqMan®, correlating its expression with BCR::ABL1 p190+, to evaluate its influence in the clinic of adult patients. Results: We found that PARP1 is expressed differently in ALL, AML and CML and that p190 transcripts do not follow a linear pattern in these populations. We also found that PARP1 expression is not correlated with age, white blood cell and the amount of p190 transcripts. Conclusion: Despite the lack of statistical correlation between the variables analyzed, the role of PARP1 in BCR::ABL1 leukemia cannot be ruled out, given the instability profile promoted by this translocation. Finally, further studies involving a larger sample of patients are needed, as well as investigations into other molecular pathways that may impact on the pathogenesis of different BCR::ABL1 leukemic subtypes.

Identification of a novel DNA oxidative damage repair pathway, requiring the ubiquitination of the histone variant macroH2A1.1.

BACKGROUND: The histone variant macroH2A (mH2A), the most deviant variant, is about threefold larger than the conventional histone H2A and consists of a histone H2A-like domain fused to a large Non-Histone Region responsible for recruiting PARP-1 to chromatin. The available data suggest that the histone variant mH2A participates in the regulation of transcription, maintenance of heterochromatin, NAD+ metabolism, and double-strand DNA repair. RESULTS: Here, we describe a novel function of mH2A, namely its implication in DNA oxidative damage repair through PARP-1. The depletion of mH2A affected both repair and cell survival after the induction of oxidative lesions in DNA. PARP-1 formed a specific complex with mH2A nucleosomes in vivo. The mH2A nucleosome-associated PARP-1 is inactive. Upon oxidative damage, mH2A is ubiquitinated, PARP-1 is released from the mH2A nucleosomal complex, and is activated. The in vivo-induced ubiquitination of mH2A, in the absence of any oxidative damage, was sufficient for the release of PARP-1. However, no release of PARP-1 was observed upon treatment of the cells with either the DNA alkylating agent MMS or doxorubicin. CONCLUSIONS: Our data identify a novel pathway for the repair of DNA oxidative lesions, requiring the ubiquitination of mH2A for the release of PARP-1 from chromatin and its activation.

Mechanism of PARP1 Elongation Reaction Revealed by Molecular Modeling.

Poly(ADP-ribose) polymerase 1 (PARP1) plays a major role in the DNA damage repair and transcriptional regulation, and is targeted by a number of clinical inhibitors. Despite this, catalytic mechanism of PARP1 remains largely underexplored because of the complex substrate/product structure. Using molecular modeling and metadynamics simulations we have described in detail elongation of poly(ADP-ribose) chain in the PARP1 active site. It was shown that elongation reaction proceeds via the SN1-like mechanism involving formation of the intermediate furanosyl oxocarbenium ion. Intriguingly, nucleophilic 2'A-OH group of the acceptor substrate can be activated by the general base Glu988 not directly but through the proton relay system including the adjacent 3'A-OH group.

The Rate of NAD+ Breakdown Is Maintained Constant against Deletion or Overexpression of NAD+-Degrading Enzymes in Mammalian Cells.

Cellular NAD+ is continuously degraded and synthesized under resting conditions. In mammals, NAD+ synthesis is primarily initiated from nicotinamide (Nam) by Nam phosphoribosyltransferase, whereas poly(ADP-ribose) polymerase 1 (PARP1) and 2 (PARP2), sirtuin1 (SIRT1), CD38, and sterile alpha and TIR motif containing 1 (SARM1) are involved in NAD+ breakdown. Using flux analysis with 2H-labeled Nam, we found that when mammalian cells were cultured in the absence of Nam, cellular NAD+ levels were maintained and NAD+ breakdown was completely suppressed. In the presence of Nam, the rate of NAD+ breakdown (RB) did not significantly change upon PARP1, PARP2, SIRT1, or SARM1 deletion, whereas stable expression of CD38 did not increase RB. However, RB in PARP1-deleted cells was much higher compared with that in wild-type cells, in which PARP1 activity was blocked with a selective inhibitor. In contrast, RB in CD38-overexpressing cells in the presence of a specific CD38 inhibitor was much lower compared with that in control cells. The results indicate that PARP1 deletion upregulates the activity of other NADases, whereas CD38 expression downregulates the activity of endogenous NADases, including PARP1 and PARP2. The rate of cellular NAD+ breakdown and the resulting NAD+ concentration may be maintained at a constant level, despite changes in the NAD+-degrading enzyme expression, through the compensatory regulation of NADase activity.

[Metastatic castration-resistant prostate cancer and PARP inhibitors: From tumor genomics to new therapeutic combinations]. / Cancer de prostate métastatique résistant à la castration et inhibiteurs de PARP : de la génomique tumorale aux nouvelles associations thérapeutiques.

Castration-resistant metastatic prostate cancer remains lethal and a therapeutic challenge. Current strategies are geared towards the personalization of treatments based on the identification of relevant molecular targets, including genomic alterations involved in tumoral processes. Among these novel targeted therapies, poly-ADP-ribose polymerase inhibitors (PARPi), by blocking the action of enzymes involved in deoxyribonucleic acid (DNA) repair, induce the destruction of cells carrying defects in homologous recombination repair, often associated with alterations in genes involved in this mechanism. Thus, determining the presence of a molecular anomaly, particularly alterations in the BRCA1/2 genes, is a prerequisite for initiating PARPi monotherapy. In patients with metastatic castration-resistant prostate cancer , around 20-30 % carry this type of mutation. In this population, single-agent studies have demonstrated PARPi ability to prolong overall survival, and to improve symptom control, including pain. Other studies are underway to assess their effectiveness in combination with other therapies, and it already appears that association with new-generation hormone therapy can further prolong radiological progression-free survival, regardless of the mutation status of the genes involved in DNA repair, indicating a synergistic action between PARPi and new-generation hormone therapy.

A panel-based mutational signature of homologous recombination deficiency associates with response to PARP inhibition in metastatic castration-resistant prostate cancer.

BACKGROUND: The PARP inhibitor (PARPi) olaparib is approved for homologous recombination repair (HRR) gene-altered metastatic castration-resistant prostate cancer (mCRPC). However, there is significant heterogeneity in response to PARPi in patients with mCRPC. Better clinical biomarkers are needed to identify patients likely to benefit from PARPi. METHODS: Patients with prostate adenocarcinoma and panel sequencing at Dana-Farber Cancer Institute were identified. Mutational signature analysis was performed using SigMA to characterize tumors as HRR deficient (HRD). The validity of SigMA to identify patients likely to benefit from olaparib was compared to the current FDA label (presence of a deleterious alteration in one of 14 HRR genes). RESULTS: 546 patients were identified, of which 34% were HRD. Among patients with HRR gene alterations, only patients with BRCA2 two-copy loss (2CL) were more likely to be HRD compared to patients without HRR gene alterations (74% vs 31%; P = 9.1 × 10-7). 28 patients with mCRPC received olaparib, of which 13 were HRD and 9 had BRCA2 2CL. SigMA improved upon the current FDA label for predicting PSA50 (sensitivity: 100% vs 90%; specificity: 83% vs 44%; PPV: 77% vs 47%; NPV: 100% vs 89%) and rPFS > 6 months (sensitivity: both 92%; specificity: 93% vs 53%; PPV: 92% vs 63%; NPV: 93% vs 89%). On multivariate analysis, incorporating prognostic clinical factors and HR gene alterations, SigMA-predicted HRD independently associated with improved PSA-PFS (HR = 0.086, p = 0.00082) and rPFS (HR = 0.078, p = 0.0070). CONCLUSIONS: SigMA-predicted HRD may better identify patients likely to benefit from olaparib as compared to the current FDA label. Larger studies are needed for further validation.

FHOD3 shows clinical significance in progression of ovarian cancer through regulation of caspase-3 signaling pathway.

Ovarian cancer is a malignant disease threatening women's life. Traditional therapies bring little benefits for the patients with distant metastasis or recurrence. FHOD3 gene was reported to promote progression in cancer. However, the role of FHOD3 in ovarian cancer is not known yet. To investigate the role of FHOD3 gene in the progression of ovarian cancer and its molecular mechanism, FHOD3 gene was successfully knocked down in ovarian cancer cell lines. Then cell behaviors includes proliferation, migration, invasion, and apoptosis were detected. The data demonstrated that cell proliferation, migration, and invasion ability were suppressed after FHOD3 knockdown. Cell apoptosis was induced reversely. Moreover, caspase-3-mediated signaling pathway was activated after FHOD3 knockdown, and activity of caspase-3 further supported this finding. In addition, PARP inhibitor, Olaparib showed much more potent inhibition in ovarian cancer cells with FHOD3 knockdown. In clinical ovarian cancer tissues, FHOD3 gene showed increased expression compared to adjacent normal tissues. And FHOD3 gene expression level was negatively correlated to the patients' survival. Overall, these findings shed light on the significance of FHOD3 gene in progression of ovarian cancer. This study showed that FHOD3 gene might be exploited as a new target to improve the clinical outcome of ovarian cancer.

Case report: Germline BRCA 2 mutation in primary peritoneal carcinoma: a rare malignancy.

Background: Primary peritoneal carcinoma (PPC) is a rare malignancy. Clinically, its histological morphology resembles that of epithelial ovarian tumors (EOC), often leading to misdiagnosis. Diagnosis and treatment of PPC are time-sensitive because of the rapidly progressive nature of the disease. Case report: Herein, we report the case of a 54-year-old woman who was initially diagnosed with ovarian cancer; however, extensive workup showed evidence of Müllerian PPC origin. Furthermore, the patient harbored a targetable BRCA mutation. Conclusion: The patient was treated with the BRCA-targeting agents and had a good prognosis after surgery.

Niraparib first-line maintenance therapy in patients with newly diagnosed advanced ovarian cancer: final overall survival results from the PRIMA/ENGOT-OV26/GOG-3012 trial.

BACKGROUND: The phase III PRIMA/ENGOT-OV26/GOG-3012 trial met its primary endpoint. Niraparib first-line maintenance significantly prolonged progression-free survival (PFS) among patients with newly diagnosed advanced ovarian cancer that responded to first-line platinum-based chemotherapy, regardless of homologous recombination deficiency (HRD) status. Final overall survival (OS) results are reported. PATIENTS AND METHODS: Patients were randomized 2:1 to niraparib or placebo, stratified by response to first-line treatment, receipt of neoadjuvant chemotherapy, and tumor HRD status. After reaching 60% target maturity, OS was evaluated via a stratified log-rank test using randomization stratification factors and summarized using Kaplan-Meier methodology. OS testing was hierarchical [overall population first, then the homologous recombination-deficient (HRd) population]. Other secondary outcomes and long-term safety were assessed; an updated, ad hoc analysis of investigator-assessed PFS was also conducted (cut-off date, 8 April 2024). RESULTS: The median follow-up was 73.9 months. In the overall population, the OS hazard ratio was 1.01 [95% confidence interval (CI) 0.84-1.23; P = 0.8834] for niraparib (n = 487) versus placebo (n = 246). In the HRd (n = 373) and homologous recombination-proficient (n = 249) populations, the OS hazard ratios were 0.95 (95% CI 0.70-1.29) and 0.93 (95% CI 0.69-1.26), respectively. Subsequent poly(ADP-ribose) polymerase inhibitor therapy was received by 11.7% and 15.8% of niraparib patients and 37.8% and 48.4% of placebo patients in the overall and HRd populations, respectively. The 5-year PFS rate numerically favored niraparib in the overall (niraparib, 22%; placebo, 12%) and HRd populations (niraparib, 35%; placebo, 16%). Myelodysplastic syndromes/acute myeloid leukemia incidence was <2.5% (niraparib, 2.3%; placebo, 1.6%). No new safety signals were observed. CONCLUSIONS: In patients with newly diagnosed advanced ovarian cancer at high risk of recurrence, there was no difference in OS between treatment arms. In the HRd population, patients alive at 5 years were two times as likely to be progression free with niraparib treatment than placebo. Long-term safety remained consistent with the established niraparib safety profile.

Efficacy of a platinum-based chemotherapy rechallenge for platinum-sensitive recurrence after PARP inhibitor maintenance.

Objective: Platinum-free interval (PFI) is the period from the end of platinum-based chemotherapy to the date of recurrence. If the PFI is > 6 months, a platinum-based chemotherapy rechallenge is considered; however, its efficacy after poly adenosine 5'-diphosphate-ribose polymerase (PARP) inhibitor maintenance therapy is unknown. This study aimed to examine the efficacy of a platinum-based chemotherapy rechallenge after PARP inhibitor therapy. Methods: We retrospectively evaluated patients with ovarian cancer with a PFI≥6 months with PARP inhibitor maintenance therapy, receiving platinum-based chemotherapy. Duration of PARP inhibitor therapy, best response to subsequent platinum chemotherapy rechallenge, and clinical characteristics were collected from medical records. Tumor response was assessed according to RECIST 1.1. Correlations were calculated using Spearman's correlation coefficients. Results: Among the 10 included patients, seven (70 %) received PARP inhibitors after primary chemotherapy, and three (30 %) received chemotherapy for platinum-sensitive relapse. One and five patients harbored a germline BRCA1 and BRCA wild-type mutations, respectively, and two had homologous recombination proficiency. The median PFI was 303.5 (182-602) days, and PARP inhibitor therapy duration was 249 (147-570) days. Platinum chemotherapy rechallenge efficacy was complete and partial response and stable disease in one (10 %), six (60 %), and three (30 %) patients, respectively. The longer the duration of PARP inhibitor treatment, better the response to platinum agents (Spearman correlation coefficient 0.284, p = 0.0288). Conclusion: Platinum-based chemotherapy rechallenge is reasonable for patients with platinum-sensitive disease, using the traditional PFI cutoff of 6 months, even when the PFI is obtained with a maintenance PARP inhibitor.

Real-world trends in the use of maintenance therapy in ovarian cancer across the United States from 2017 to 2021.

OBJECTIVE: We assessed real-world trends in the use of maintenance therapy [MT] (i.e., polyADP-ribose polymerase inhibitors (PARPi) and/or bevacizumab following platinum-based chemotherapy), among U.S. patients with ovarian cancer. METHODS: Using Medicare and commercial administrative health claims data from Optum's de-identified Clinformatics® Data Mart Database, we identified patients who had been diagnosed with ovarian cancer between January 1, 2010, and March 31, 2021, and received platinum-based chemotherapy and MT. Multivariable logistic regression and Cox proportional hazards regression were used to evaluate associations between demographic and clinical characteristics and MT use. RESULTS: Our study included 6339 patients, with a median age of 70 years. The majority were White (70.1 %), Medicare-insured (71.9 %), and were treated in the South (42.5 %). Of the 31.5 % who received MT, 18.1 % received bevacizumab alone, 10.2 % PARPi alone, and 3.3 % both. After adjusting for insurance type, PARPi and bevacizumab use increased significantly from 2017 to 2020. Patients with a high Elixhauser comorbidity index were more likely to receive MT than were patients with a low index [OR (95 % CI): 1.46 (1.28-1.67), p < 0.0001]. PARPi use was significantly associated with treatment in the South [1.42 (1.10-1.83), p = 0.01]. Compared to patients who received neither agents, those who received bevacizumab, alone or in combination with PARPi, had a higher risk of death [HR = 2.02 (95 % CI: 1.70-2.28, p < 0.0001) and 1.66 (1.24-2.23), p = 0.001, respectively]. CONCLUSIONS: The majority of patients with ovarian cancer are not utilizing maintenance therapy after platinum-based chemotherapy. Age, comorbidity status, and geographic region of treatment were associated with MT use. Understanding the factors and real-world outcomes associated with MT use is important to support patients in making value concordant and informed decisions.