Niraparib for the treatment of metastatic ccRCC in a patient with CDK12 and RAD51C mutations: a case report.

Background: Niraparib, a poly ADP-ribose polymerase inhibitors (PARPi), has been widely applied in the intervention of epithelial ovarian, fallopian tube, or primary peritoneal cancer. Nevertheless, as of the present moment, there are limited instances demonstrating favorable outcomes stemming from niraparib therapy in patients with clear cell renal cell carcinoma (ccRCC). Case presentation: Here, we report a case of a 50-year-old patient with ccRCC who subsequently developed distant metastasis. The patient received monotherapy with pazopanib and combination therapy with axitinib and tislelizumab, demonstrating limited efficacy. Liquid biopsy revealed missense mutations in the CDK12 and RAD51C of the homologous recombination repair (HRR) pathway, suggesting potential sensitivity to PARPi. Following niraparib treatment, the patient's condition improved, with no significant side effects. Conclusion: In summary, patients with ccRCC harboring HRR pathway gene mutation may potentially benefit from niraparib. This will present more options for ccRCC patients with limited response to conventional treatments.

Feasibility of Indirect Treatment Comparisons Between Niraparib Plus Abiraterone Acetate and Other First-Line Poly ADP-Ribose Polymerase Inhibitor Treatment Regimens for Patients with BRCA1/2 Mutation-Positive Metastatic Castration-Resistant Prostate Cancer.

INTRODUCTION: Poly(ADP-ribose) polymerase inhibitors (PARPi) are a novel option to treat patients with metastatic castration-resistant prostate cancer (mCRPC). Niraparib plus abiraterone acetate and prednisone (AAP) is indicated for BRCA1/2 mutation-positive mCRPC. Niraparib plus AAP demonstrated safety and efficacy in the phase 3 MAGNITUDE trial (NCT03748641). In the absence of head-to-head studies comparing PARPi regimens, the feasibility of conducting indirect treatment comparisons (ITC) to inform decisions for patients with first-line BRCA1/2 mutation-positive mCRPC has been explored. METHODS: A systematic literature review was conducted to identify evidence from randomized controlled trials on relevant comparators to inform the feasibility of conducting ITCs via network meta-analysis (NMA) or population-adjusted indirect comparisons (PAIC). Feasibility was assessed based on network connectivity, data availability in the BRCA1/2 mutation-positive population, and degree of within- and between-study heterogeneity or bias. RESULTS: NMAs between niraparib plus AAP and other PARPi regimens (olaparib monotherapy, olaparib plus AAP, and talazoparib plus enzalutamide) were inappropriate due to the disconnected network, differences in trial populations related to effect modifiers, or imbalances within BRCA1/2 mutation-positive subgroups. The latter issue, coupled with the lack of a common comparator (except for olaparib plus AAP), also rendered anchored PAICs infeasible. Unanchored PAICs were either inappropriate due to lack of population overlap (vs. olaparib monotherapy) or were restricted by unmeasured confounders and small sample size (vs. olaparib plus AAP). PAIC versus talazoparib plus enzalutamide was not possible due to lack of published arm-level baseline characteristics and sufficient efficacy outcome data in the relevant population. CONCLUSION: The current randomized controlled trial evidence network does not permit robust comparisons between niraparib plus AAP and other PARPi regimens for patients with 1L BRCA-positive mCRPC. Decision-makers should scrutinize any ITC results in light of their limitations. Real-world evidence combined with clinical experience should inform treatment recommendations in this indication.

ATM, BLM, and CDH1 gene co-mutations in a high-grade endometrial stromal sarcoma patient with multiple abdominal cavity metastases: a case report and literature review.

BACKGROUND: High-grade endometrial stromal sarcoma (HG-ESS) is a rare malignant tumor with poor prognosis. To overcome the limitations of current treatment for advanced patients, the intervention of targeted drug therapy is urgently needed. CASE PRESENTATION: A 74-year-old married woman who presented with abdominal distension and lower abdominal pain was admitted to Hebei General Hospital. After surgery, immunohistochemical staining revealed a malignant tumor which was consistent with HG-ESS. Tumor recurrence occurred 2 months after surgery. Then the patient underwent chemotherapy with two courses but responded poorly. Subsequently we observed ATM, BLM, and CDH1 co-mutations by Next Generation Sequencing (NGS). Then the patient received pamiparib, which resulted in a 10-month progression-free survival (PFS) and is now stable with the administration of sintilimab in combination with pamiparib and anlotinib. CONCLUSIONS: Due to the successful use of poly ADP-ribose polymerase inhibitor (PARPi) on HG-ESS, we suggest that the selection of effective targeted drugs combined with anti- programmed death-1 (PD-1) drug therapy based on genetic testing may become a new option for the treatment of homologous repair deficient (HR-deficient) HG-ESS.

Real-world TRAE association between niraparib and platinum-based chemotherapy.

Background: Pre-clinical studies showed the anti-tumor mechanisms of PARP inhibitors (PARPi) and platinum have some crossover and overlap in the DNA damage repair pathway, patients who respond to platinum-based chemotherapy are also more likely to be sensitive to PARPi. This real-world study mainly aimed to evaluate whether TRAE (treatment-related adverse event) between platinum based chemotherapy (PBC) and niraparib are also associated. Methods: Patients received niraparib as maintenance treatment or salvage therapy for advanced ovarian cancer at the First Affiliated Hospital of Gannan Medical University from January 2020 to August 2023 were included. Survival data of niraparib treatment and adverse events occurred during the last platinum-based chemotherapy cycle before starting niraparib treatment and during niraparib treatment are documented. Fisher's exact test were used for correlation analysis. Results: 1. 40 patients treated with niraparib were included in the analysis, including 31 patients treated with niraparib for 1st-line maintenance therapy, 6 patients for PSR (platinum-sensitive recurrence) maintenance therapy, and 3 patients for salvage therapy. The overall median follow-up time was 15.0 months (ranged from 2.2 months to 32.1 months). 2. Overall grade≥3 TRAE (40% vs 70%, p=0.012) including anemia (20% vs 45%, p=0.041) and neutrophil count decreased (17.5% vs 57.5%, p<0.001) was significantly lower during niraparib treatment compared to during chemotherapy. 3. Any grade TRAE (75% vs 100%, p=0.002) including white blood cell count decreased (47.5% vs 87.5%, p<0.001), red blood cell count decreased (57.5% vs 92.5%, p<0.001), anemia (55% vs 87.5%, p<0.001) and neutrophil count decreased (35% vs 85%, p<0.001) were also significantly lower in niraparib treatment group compared with chemotherapy group. No new safety signals were identified. Conclusion: 1. In this real-world practice, we observed that patients with advanced ovarian cancer who experienced any grade and grade ≥3 TRAE during chemotherapy were well tolerated when treated with niraparib, particularly the incidence of any grade and grade ≥3 anemia, and neutrophil count decreased during niraparib treatment were significantly lower compared with that during chemotherapy. 2. For patients with ovarian cancer who have experienced grade ≥3 hematological adverse reactions during prior platinum-based chemotherapy, greater attention should be paid to the monitoring and management of hematological adverse reactions during subsequent treatment with niraparib.

Poly (adenosine diphosphate-ribose) polymerase inhibitors in the treatment of triple-negative breast cancer with homologous repair deficiency.

Breast cancer (BC) is a highly heterogeneous disease, and the presence of germline breast cancer gene mutation (gBRCAm) is associated with a poor prognosis. Triple-negative breast cancer (TNBC) is a BC subtype, characterized by the absence of hormone and growth factor receptor expression, making therapeutic decisions difficult. Defects in the DNA damage response pathway due to mutation in breast cancer genes (BRCA 1/2) lead to homologous recombination deficiency (HRD). However, in HRD conditions, poly (adenosine diphosphate-ribose) polymerase (PARP) proteins repair DNA damage and lead to tumor cell survival. Biological understanding of HRD leads to the development of PARP inhibitors (PARPi), which trap PARP proteins and cause genomic instability and tumor cell lysis. HRD assessment can be an important biomarker in identifying gBRCAm patients with BC who could benefit from PARPi therapy. HRD can be identified by homologous recombination repair (HRR) gene-based assays, genomic-scarring assays and mutational signatures, transcription and protein expression profiles, and functional assays. However, gold standard methodologies that are robust and reliable to assess HRD are not available currently. Hence, there is a pressing need to develop accurate biomarkers identifying HRD tumors to guide targeted therapies such as PARPi in patients with BC. HRD assessment has shown fruitful outcomes in chemotherapy studies and preliminary evidence on PARPi intervention as monotherapy and combination therapy in HRD-stratified patients. Furthermore, ongoing trials are exploring the potential of PARPi in BC and clinically complex TNBC settings, where HRD testing is used as an adjunct to stratify patients based on BRCA mutations.

CA-125 KELIM as an Alternative Predictive Tool to Identify Which Patients Can Benefit from PARPi in High-Grade Serous Advanced Ovarian Cancer: A Retrospective Pilot Diagnostic Accuracy Study.

BRCA mutation and homologous recombination deficiency (HRD) are the criteria for the administration of PARP inhibitor (PARPi) maintenance therapy. It is known that PARPi efficacy is related to platinum sensitivity and that the latter can be demonstrated from the CA-125 elimination rate constant (KELIM). This study aims to investigate if KELIM can be another tool in the identification of patients that could be benefit from PARPi therapy. Retrospective analysis of patients with high-grade serous advanced ovarian cancer that underwent cytoreduction and was further tested for HRD status. The HRD status was tested either by myChoice HRD CDx assay or by RediScore assay. KELIM score was measured in both neoadjuvant and adjuvant settings with the online tool biomarker-kinetics.org. A total of 39 patients had available data for estimating both HRD status and KELIM score. When assuming KELIM as a binary index test with the value 1 as the cut-off point, the sensitivity was 0.86, 95% CI (0.64-0.97) and the specificity was 0.83, 95% CI (0.59-0.96). On the other hand, when assuming KELIM as a continuous index test, the area under the curve (AUC) was 81% and the optimal threshold, using the Youden index, was identified as 1.03 with a sensitivity of 85.7% and a specificity of 83.3%. KELIM score seems to be a new, cheaper, and faster tool to identify patients that can benefit from PARPi maintenance therapy.

PARP1-DOT1L transcription axis drives acquired resistance to PARP inhibitor in ovarian cancer.

BACKGROUND: Poly (ADP-ribose) polymerase inhibitor (PARPi) resistance poses a significant challenge in ovarian carcinoma (OC). While the role of DOT1L in cancer and chemoresistance is acknowledged, its specific role in PARPi resistance remains unclear. This study aims to elucidate the molecular mechanism of DOT1L in PARPi resistance in OC patients. METHODS: This study analyzed the expression of DOT1L in PARPi-resistant cell lines compared to sensitive ones and correlated it with clinical outcomes in OC patients. Comprehensive in vitro and in vivo functional experiments were conducted using cellular and mouse models. Molecular investigations, including RNA sequencing, chromatin immunoprecipitation (ChIP) and Cleavage Under Targets and Tagmentation (CUT&Tag) assays, were employed to unravel the molecular mechanisms of DOT1L-mediated PARPi resistance. RESULTS: Our investigation revealed a robust correlation between DOT1L expression and clinical PARPi resistance in non-BRCA mutated OC cells. Upregulated DOT1L expression in PARPi-resistant tissues was associated with diminished survival in OC patients. Mechanistically, we identified that PARP1 directly binds to the DOT1L gene promoter, promoting transcription independently of its enzyme activity. PARP1 trapping induced by PARPi treatment amplified this binding, enhancing DOT1L transcription and contributing to drug resistance. Sequencing analysis revealed that DOT1L plays a crucial role in the transcriptional regulation of PLCG2 and ABCB1 via H3K79me2. This established the PARP1-DOT1L-PLCG2/ABCB1 axis as a key contributor to PARPi resistance. Furthermore, we discovered that combining a DOT1L inhibitor with PARPi demonstrated a synergistic effect in both cell line-derived xenograft mouse models (CDXs) and patient-derived organoids (PDOs). CONCLUSIONS: Our results demonstrate that DOT1L is an independent prognostic marker for OC patients. The PARP1-DOT1L/H3K79me2-PLCG2/ABCB1 axis is identified as a pivotal contributor to PARPi resistance. Targeted inhibition of DOT1L emerges as a promising therapeutic strategy for enhancing PARPi treatment outcomes in OC patients.

Paris saponin VII reverses resistance to PARP inhibitors by regulating ovarian cancer tumor angiogenesis and glycolysis through the RORα/ECM1/VEGFR2 signaling axis.

The emergence of Poly (ADP-ribose) polymerase inhibitors (PARPi) has marked the beginning of a precise targeted therapy era for ovarian cancer. However, an increasing number of patients are experiencing primary or acquired resistance to PARPi, severely limiting its clinical application. Deciphering the underlying mechanisms of PARPi resistance and discovering new therapeutic targets is an urgent and critical issue to address. In this study, we observed a close correlation between glycolysis, tumor angiogenesis, and PARPi resistance in ovarian cancer. Furthermore, we discovered that the natural compound Paris saponin VII (PS VII) partially reversed PARPi resistance in ovarian cancer and demonstrated synergistic therapeutic effects when combined with PARPi. Additionally, we found that PS VII potentially hindered glycolysis and angiogenesis in PARPi-resistant ovarian cancer cells by binding and stabilizing the expression of RORα, thus further inhibiting ECM1 and interfering with the VEGFR2/FAK/AKT/GSK3ß signaling pathway. Our research provides new targeted treatment for clinical ovarian cancer therapy and brings new hope to patients with PARPi-resistant ovarian cancer, effectively expanding the application of PARPi in clinical treatment.

Exploration of poly (ADP-ribose) polymerase inhibitor resistance in the treatment of BRCA1/2-mutated cancer.

Breast cancer susceptibility 1/2 (BRCA1/2) genes play a crucial role in DNA damage repair, yet mutations in these genes increase the susceptibility to tumorigenesis. Exploiting the synthetic lethality mechanism between BRCA1/2 mutations and poly(ADP-ribose) polymerase (PARP) inhibition has led to the development and clinical approval of PARP inhibitor (PARPi), representing a milestone in targeted therapy for BRCA1/2 mutant tumors. This approach has paved the way for leveraging synthetic lethality in tumor treatment strategies. Despite the initial success of PARPis, resistance to these agents diminishes their efficacy in BRCA1/2-mutant tumors. Investigations into PARPi resistance have identified replication fork stability and homologous recombination repair as key factors sensitive to PARPis. Additionally, studies suggest that replication gaps may also confer sensitivity to PARPis. Moreover, emerging evidence indicates a correlation between PARPi resistance and cisplatin resistance, suggesting a potential overlap in the mechanisms underlying resistance to both agents. Given these findings, it is imperative to explore the interplay between replication gaps and PARPi resistance, particularly in the context of platinum resistance. Understanding the impact of replication gaps on PARPi resistance may offer insights into novel therapeutic strategies to overcome resistance mechanisms and enhance the efficacy of targeted therapies in BRCA1/2-mutant tumors.

Current Systemic Therapy in Men with Metastatic Castration-Sensitive Prostate Cancer.

PURPOSE OF REVIEW: This review aims to explore the evolving landscape of treatments available for metastatic castration-sensitive prostate cancer (mCSPC) patients. RECENT FINDINGS: In less than a decade, evidence was chronologically provided that (1) systemic treatment intensification with docetaxel improves outcomes, including survival, in men with mCSPC, (2) then that these outcomes are also improved when a second-generation androgen receptor pathway inhibitor (ARPI) is combined with androgen deprivation therapy (ADT), and (3) using a "triplet systemic therapy," which consists in the combination of ADT, an ARPI and docetaxel, further improves outcomes, including survival. Radiotherapy to the prostate combined with ADT alone is now recommended in men with low-volume mCSPC. Combining prostate radiotherapy and intensified systemic treatment including abiraterone may be synergistic as suggested in the PEACE-1 trial. Also, the role of metastases-directed local therapies (mostly stereotactic radiotherapy) is currently being assessed in phase 3 trials. Finally, the integration of biomarkers (e.g. BRCA2 gene alterations, PTEN loss, PSMA expression) for decision making is not currently established, though trials are also currently underway. Importantly, most evidence currently available was obtained in men with de novo metastases, while for those with metastatic relapse after definitive local treatment, the role of treatment intensification is less well established. Treatment intensification is nowadays the standard of care for patients with de novo mCSPC as it leads to outcomes improvement, including survival, and the standard of care is evolving almost on a yearly basis.

Thromboembolic risk in prostate cancer patients treated with PARP inhibitors: A systematic review and meta-analysis.

BACKGROUND: Poly (ADP-ribose) polymerase inhibitors (PARPi) have been associated with thrombotic events, although the association with thrombosis risk in different cancers remains poorly defined. METHODS: This meta-analysis included phase II and phase III clinical trials in which patients with metastatic prostate cancer were treated with PARPi either as monotherapy or in combination. The primary endpoints were the rates of thromboembolic events in prostate cancer patients. RESULTS: A total of 2210 and 1662 patients with prostate cancer were compared in the PARP inhibitor and control groups, respectively. 96 (4.3 %) and 37 (2.2 %) patients had thrombosis in the PARPi and control groups, respectively. PARPi had a statistically significant increased risk of thrombosis in prostate cancer patients (Odds Ratio (OR)=1.98, 95 % CI: 1.06-3.70, P=0.030). CONCLUSION: The heightened thrombotic risk associated with PARPi treatment in prostate cancer emphasizes the need for comprehensive management protocols to effectively reduce the risk and ensure safer outcomes.

Subsequent management and outcomes after first-line PARP inhibitors progression in ovarian cancer patients.

OBJECTIVES: This retrospective study aims to evaluating the subsequent management and outcomes after first-line PARPi progression in Chinese ovarian cancer population. METHODS: Clinical and pathologic variables, treatment modalities, and outcomes were assessed. We investigated the subsequent management and outcomes after first-line PARPi progression. The objective response rate (ORR) and disease control rate (DCR) parameters were evaluated to determine the response to subsequent chemotherapy. For the survival analyses, progression-free survival 1 (PFS1), PFS2, overall survival (OS) and PFS2 - PFS1 were analysed. RESULTS: A total of 124 patients received PARPi maintenance treatment after first-line chemotherapy during the study period in our center. 44 of them (35.5%) experienced a recurrence. The median duration of PARPi in these patients was 11.1 months (range: 1.2-75.1 months). A total of 40 patients (40/44, 90.9%) received subsequent chemotherapy with 35 (35/44, 79.5%) and 5 (5/44, 11.4%) patients received platinum-based and non-platinum-based chemotherapy in our center. 2 patients (4.5%) received target therapy and other 2 patients (4.5%) received best supportive care. 27.3% (12/44) patients received secondary cytoreduction surgery (SCS). After subsequent chemotherapy, 14 patients received PARPi retreatment as maintenance therapy. In patients who received platinum-based regimens (n = 35), 23 of 35 patients (65.7%) had complete/partial response (CR/PR), 8 of 35 (22.9%) had stable disease (SD), and 4 of 35 (12.1%) had progressive disease (PD). The ORR and DCR of patients who received subsequent chemotherapy was 65.7% and 88.6%, respectively. 15 patients (57.7%, 15/26) were reported to be platinum resistant with a platinum-free interval (PFI) of < 6 months in patients whose platinum sensitivity of the second line platinum-based regimens was evaluable. Patients who received SCS after PARPi resistant associated with a borderline better PFS2 (median PFS2: 41.9 vs. 29.2 months, P = 0.051) and a non-significantly increased PFS2-PFS1 (median PFS2-PFS1: 12.2 vs. 9.8 months, P = 0.551). Patients with a PFI ≥ 12 months had a significantly better PFS2 (median PFS2: 37.0 vs. 25.3 months, P < 0.001) and a tendency towards a better PFS2-PFS1 than those with a PFI < 12 months (median PFS2-PFS1: 11.2 vs. 8.5 months, P = 0.334). A better PFS2 was observed in patients who received second PARPi maintenance therapy (median PFS2 of 35.4 vs. 28.8 months); however, the difference was not statistically significant (P = 0.200). A better PFS2-PFS1 was observed in patients who received second PARPi maintenance therapy (median PFS2-PFS1: 13.6 vs. 8.9 months, P = 0.002) than those without. CONCLUSIONS: In summary, some degree of resistance to standard subsequent platinum and non-platinum chemotherapy is noted in the entire cohort. A trend towards higher benefit from subsequent chemotherapy after first-line PARP inhibitors progression was observed in the PFI ≥ 12 months subgroup than those with PFI < 12 months. PARPi retreatment as maintenance therapy and SCS can be offered to some patients with PARPi resistance.

Discovery of Novel 4-Hydroxyquinazoline Derivatives: In Silico, In Vivo and In Vitro Studies Using Primary PARPi-Resistant Cell Lines.

A series of novel 4-Hydroxyquinazoline derivatives were designed and synthesized to enhance sensitivity in primary PARPi-resistant cells. Among them, the compound B1 has been found to have superior cytotoxicity in primary PARPi-resistant HCT-15 and HCC1937 cell lines, and dose-dependently suppressed the intracellular PAR formation and enhanced the γH2AX aggregation. Mechanistic study showed that B1 stimulated the formation of intracellular ROS and the depolarization of the mitochondrial membrane, which could increase apoptosis and cytotoxicity. An in vivo study showed that B1 significantly suppressed tumor growth at a dose of 25 mg/kg, and an acute toxicity study confirmed its safety. Molecular docking and dynamics simulations revealed that hydrogen bonding between B1 and ASP766 may be helpful to enhance anti-drug resistance ability. This study suggests that B1 is a potent PARP inhibitor that can overcome PARPi resistance and deserves further investigation.

Precision Medicine in Castration-Resistant Prostate Cancer: Advances, Challenges, and the Landscape of PARPi Therapy-A Narrative Review.

After recent approvals, poly-adenosine diphosphate [ADP]-ribose polymerase inhibitors (PARPis) have emerged as a frontline treatment for metastatic castration-resistant prostate cancer (mCRPC). Unlike their restricted use in breast or ovarian cancers, where approval is limited to those with BRCA1/2 alterations, PARPis in mCRPC are applied across a broader spectrum of genetic aberrations. Key findings from the phase III PROPEL trial suggest that PARPis' accessibility may broaden, even without mandatory testing. An increasing body of evidence underscores the importance of distinct alterations in homologous recombination repair (HRR) genes, revealing unique sensitivities to PARPis. Nonetheless, despite the initial effectiveness of PARPis in treating BRCA-mutated tumors, resistance to therapy is frequently encountered. This review aims to discuss patient stratification based on biomarkers and genetic signatures, offering insights into the nuances of first-line PARPis' efficacy in the intricate landscape of mCRPC.

Arterial hypertension associated with PARPi: A meta-analysis of 41 placebo randomized controlled trials combined with a World Health Organization's pharmacovigilance study.

BACKGROUND: Arterial hypertension has been recently reported from randomized controlled trials (RCTs) assessing poly (ADP-ribose) polymerase inhibitor (PARPi). OBJECTIVE: In a context of increasing use of PARPi, it is crucial to properly assess risk and incidence of this adverse event for clinical practice. METHODS: We performed a systematic review and meta-analysis in MEDLINE, Cochrane CENTRAL and ClinicalTrials.gov up to January 4, 2023 with an ongoing surveillance up to June 7, 2023. RCTs comparing PARPi to placebo in adult patients with solid tumors were included if hypertension was reported. The primary outcome was the summary risk ratio (RR, with 95% CIs) of any hypertension of PARPi class in placebo RCTs. Secondary outcomes were the summary risk and incidence of hypertension of each individual PARPi. To provide clinical features of PARPi-associated hypertension, we independently queried the WHO's pharmacovigilance database, up to September 1, 2022. RESULTS: In total, 41 placebo RCTs (n = 15 264 adult patients) were included. PARPi class was not associated with an increased risk of hypertension compared with placebo. In individual analyses, the risk of hypertension was lower with olaparib than placebo (RR 0.77 [95% CI: 0.68-0.86], P < 0.01; I2 = 19%, χ2 P = 0.26). Niraparib monotherapy increased the risk of any (RR 2.84 [95% CI: 1.76-4.57], P < 0.01; I2 = 66%, χ2 P = 0.01) hypertension with a summary incidence of 19.87% (95% CI: 15.23-25.50). In real-life setting, niraparib-associated hypertension occurs within 20 days and was serious in 66%. Co-prescription of at least one antihypertensive or therapy-induced hypertension was reported in 20.5% or 14.4% of cases, respectively. CONCLUSIONS: In a context of extensive assessment of niraparib in combination, these data reinforce the need of a close monitoring of this adverse event to preserve its clinical benefit on patients' survival.

Safety and efficacy of Rucaparib in the treatment of ovarian cancer and patients with BRCA mutation: a systematic review and meta-analysis of phase III randomized clinical trials.

INTRODUCTION: Our systematic review and meta-analysis aimed to evaluate the clinical efficacy and safety of Rucaparib, a PARP inhibitor (PARPi), in patients with ovarian cancer and BRCA mutation. METHODS: Online databases were comprehensively searched for all phase III Randomized trials that used Rucaparib therapy for ovarian cancer patients and patients having BRCA mutation. Efficacy results are progression-free survival and overall response rate in addition to addressing its safety concerns. RESULTS: After pooling data from 4 clinical trials, the analysis showed a significant improvement in PFS among ovarian cancer patients and for the maintenance therapy with a hazard ratio (HR) of 0.49 (95% CI 0.34-0.73, p = 0.0003) and 0.42 (95% CI 0.29-0.62, p < 0.0001), respectively. For patients with BRCA mutations, the PFS showed significant improvement with a (HR) of 0.42 (95% CI 0.25-0.71, p < 0.001). A difference was observed in the risk of grade ≥ 3 TEAEs between the two groups (RR = 2.48; 95% CI 1.40-4.37). CONCLUSION: Rucaparib demonstrated significant efficacy in improving PFS and ORR in ovarian cancer patients, particularly those having BRCA mutations. However, they should be closely monitored due to the greater risk of various adverse effects.

PARP1 roles in DNA repair and DNA replication: The basi(c)s of PARP inhibitor efficacy and resistance.

Genome integrity is under constant insult from endogenous and exogenous sources. In order to cope, eukaryotic cells have evolved an elaborate network of DNA repair that can deal with diverse lesion types and exhibits considerable functional redundancy. PARP1 is a major sensor of DNA breaks with established and putative roles in a number of pathways within the DNA repair network, including repair of single- and double-strand breaks as well as protection of the DNA replication fork. Importantly, PARP1 is the major target of small-molecule PARP inhibitors (PARPi), which are employed in the treatment of homologous recombination (HR)-deficient tumors, as the latter are particularly susceptible to the accumulation of DNA damage due to an inability to efficiently repair highly toxic double-strand DNA breaks. The clinical success of PARPi has fostered extensive research into PARP biology, which has shed light on the involvement of PARP1 in various genomic transactions. A major goal within the field has been to understand the relationship between catalytic inhibition and PARP1 trapping. The specific consequences of inhibition and trapping on genomic stability as a basis for the cytotoxicity of PARP inhibitors remain a matter of debate. Finally, PARP inhibition is increasingly recognized for its capacity to elicit/modulate anti-tumor immunity. The clinical potential of PARP inhibition is, however, hindered by the development of resistance. Hence, extensive efforts are invested in identifying factors that promote resistance or sensitize cells to PARPi. The current review provides a summary of advances in our understanding of PARP1 biology, the mechanistic nature, and molecular consequences of PARP inhibition, as well as the mechanisms that give rise to PARPi resistance.

Health care services utilization in patients with ovarian cancer receiving PARP inhibitor maintenance treatment in a US community oncology setting.

OBJECTIVES: The objective of this study was to describe healthcare resource use (HCRU) in addition to treatment patterns and discontinuations, in patients with ovarian cancer (OC) initiating PARP inhibitor (PARPi) maintenance treatment in a US community oncology setting. METHODS: This was a retrospective study of patients with OC initiating PARPi monotherapy maintenance during 01/01/2017 to 06/30/2019 (followed until 12/31/2019). Patients aged ≥18 years at first diagnosis of OC with ≥2 visits within The US Oncology Network were included. Structured and chart review data as well as claims data were used to describe treatment patterns and HCRU. RESULTS: Of the 162 charts reviewed, the median age of patients was 66 years and 80% had stage III or IV disease at diagnosis. In the niraparib, rucaparib and olaparib groups, proportions of patients experiencing dose interruptions were 51%, 50%, and 28%, and discontinuations due to toxicity were 37%, 17% and 15%, respectively. Within the first 6 months, mean numbers of total claims were 43.5, 56.4, and 36.0 in the niraparib, rucaparib, and olaparib groups, and laboratory claims were 13.9, 19.4, and 15.6, respectively. Proportions of patients with hospitalizations (niraparib 40%, rucaparib 32%, olaparib 19%; p = 0.03), also differed as did emergency department visits (niraparib 37%, rucaparib 23%, olaparib 16%; p = 0.02). CONCLUSION: Despite patients initiating niraparib having higher rates of dose management events and toxicity-related discontinuations, outpatient and laboratory utilization were similar across all three PARPi. Adequate monitoring of these medications, with differing toxicities, should be emphasized to potentially decrease dose reductions and toxicities.