Rucaparib maintenance treatment for recurrent ovarian carcinoma after response to platinum therapy (ARIEL3): a randomised, double-blind, placebo-controlled, phase 3 trial

Genetic Implications for Cancer Management: The Changing Landscape of Poly (ADP-ribose) Polymerase Inhibitor Indications in the Treatment of Ovarian Cancer

Between December 2014 and May 2020, the United States Food and Drug Administration approved 9 indications for poly (ADP-ribose) polymerase (PARP) inhibitor use in ovarian cancer. Between June 2022 and September 2022, all 3 indications for PARP inhibitor treatment of recurrent ovarian cancer were withdrawn. Between November 2022 and September 2023, all 3 indications for PARP inhibitor maintenance therapy in recurrent ovarian cancer were restricted. The 3 indications for PARP inhibitor maintenance therapy in newly diagnosed advanced ovarian cancer are unchanged. This article reviews the timelines and data leading to regulatory changes for PARP inhibitor use in ovarian cancer in the United States.

Molecular mechanisms of cisplatin resistance in ovarian cancer

Ovarian cancer is one of the most common malignant tumors of the female reproductive system. The majority of patients with advanced ovarian cancer are mainly treated with cisplatin-based chemotherapy. As the most widely used first-line anti-neoplastic drug, cisplatin produces therapeutic effects through multiple mechanisms. However, during clinical treatment, cisplatin resistance has gradually emerged, representing a challenge for patient outcome improvement. The mechanism of cisplatin resistance, while known to be complex and involve many processes, remains unclear. We hope to provide a new direction for pre-clinical and clinical studies through this review on the mechanism of ovarian cancer cisplatin resistance and methods to overcome drug resistance.

SEOM-GEICO clinical guideline on epithelial ovarian cancer (2023)

In recent years, the incorporation of new strategies to the therapeutic armamentarium has completely changed the outcomes of epithelial ovarian cancer (EOC). The identification of new predictive and prognostic biomarkers has also enabled the selection of those patients more likely to respond to targeted agents. Nevertheless, EOC is still a highly lethal disease and resistance to many of these new agents is common. The objective of this guideline is to summarize the most relevant strategies to manage EOC, to help the clinician throughout the challenging diagnostic and therapeutic processes and to provide evidence-based recommendations.

How long is long enough? An international survey exploring practice variations on the recommended duration of maintenance therapy with PARP inhibitors in patients with platinum sensitive recurrent ovarian cancer and long-term outcomes

OBJECTIVE

There are no data, and thus no consensus, on the optimal duration of poly(ADP-ribose) polymerase (PARP) inhibitor maintenance therapy for exceptional responders (here defined as progression-free for 5 years or longer) with platinum sensitive recurrent ovarian cancer. The current licence is to continue PARP inhibitors until progression or toxicity; however, international practice varies considerably. The risks of late progression and late-onset myeloid malignancies, defined as occurring beyond 5 years of PARP inhibition, are unknown. This study aims to examine the practice patterns and opinions regarding the management and surveillance protocols of exceptional responders with platinum sensitive recurrent ovarian cancer.

METHODS

An online international survey of experts from June 2023 to June 2024 was carried out, disseminated at Gynaecologic Cancer Intergroup meetings and by Chairs of Cooperative Groups.

RESULTS

210 responses were received from 26 countries including Australia (27 respondents), Germany (24), the UK (21), the Netherlands (16), France (13), Spain (12), Canada (12), Italy (11), Japan (11), and other countries (63). Most respondents did not have institutional or trials group guidelines regarding duration of PARP inhibitors (154, 73.3%). For the minority with guidelines, recommendations varied: 1 year (2), 2 years (13), 3 years (4), and indefinite treatment (22). Individual practice varied considerably for those without guidelines: most (116, 76.3%) recommended ≥5 years of PARP inhibition, of which 73 (48.0%) recommended indefinite PARP inhibition. Sixty-six respondents (31.4%) reported having patients with late progression and 46 (22.0%) had cases with late-onset myeloid malignancies. Surveillance practices varied widely across all respondents.

CONCLUSIONS

This international survey highlights the diverse practice variations and disparate views on the optimal duration of maintenance therapy with PARP inhibitors in platinum sensitive recurrent ovarian cancer. The responses suggest a notable risk of late progression and myelodysplastic syndrome/acute myeloid leukemia among exceptional responders which needs confirmation. Detailed individual patient data is required to draw more reliable conclusions; another study is underway addressing this.

The Role of Tumor Biomarkers in Tailoring the Approach to Advanced Ovarian Cancer

Growing evidence has demonstrated the role of mutations of tumor biomarkers in diagnosing and treating epithelial ovarian cancer. This review aims to analyze recent literature on the correlation between tumor biomarkers and chemotherapy in nonmucinous ovarian cancer, providing suggestions for personalized treatment approaches. An extensive literature search was conducted to identify relevant studies and trials. BRCA1/2 mutations are central in homologous recombination repair deficiency (HRD) in ovarian cancer, but several other genetic mutations also contribute to varying cancer risks. While the role of MMR testing in ovarian cancer is debated, it is more commonly linked to non-serous ovarian cancer, often associated with Lynch syndrome. A significant proportion of ovarian cancer patients have HRD, affecting treatment decisions in both first-line (especially in advanced stages) and second-line therapy due to HRD's connection with platinum-based therapy and PARP inhibitors' response. However, validated genetic tests to identify HRD have not yet been universally implemented. There is no definitive therapeutic algorithm for advanced ovarian cancer, despite ongoing efforts and multiple proposed tools. Future research should focus on expanding the utility of biomarkers, reducing resistance, and increasing the actionable biomarker pool.

Effectiveness of PARP Inhibitor Maintenance Therapy in Ovarian Cancer by BRCA1/2 and a Scar-Based HRD Signature in Real-World Practice

PURPOSE

The purpose of the study was to compare the effectiveness of PARP inhibitor maintenance therapy (mPARPi) in real-world practice by biomarker status [BRCA1/2 alterations (BRCAalt) and a homologous recombination deficiency signature (HRDsig)] in advanced ovarian cancer.

EXPERIMENTAL DESIGN

Patients with ovarian cancer receiving first-line platinum-based chemotherapy and either mPARPi or no maintenance were included. Patient data were obtained by a US-based de-identified ovarian cancer Clinico-Genomic Database, from ∼280 US cancer clinics (01/2015-03/2023). Real-world progression-free survival (rwPFS) and overall survival (rwOS) were compared by biomarker status using Cox models, weighted by propensity scores.

RESULTS

Of 673 patients, 160 received mPARPi [31.2% BRCAalt and 51.9% HRDsig(+)] and 513 no maintenance [15.6% BRCAalt and 34.1% HRDsig(+)]. BRCAalt patients receiving mPARPi versus no maintenance had favorable rwPFS [HR, 0.48; 95% confidence interval (CI), 0.26-0.87; P = 0.0154], as did BRCA wild-type (WT; HR, 0.76; 95% CI, 0.57-1.01; P = 0.0595). Favorable rwOS was not observed with mPARPi for BRCAalt or BRCA-WT. HRDsig(+) patients receiving mPARPi versus no maintenance had favorable rwPFS (HR, 0.36; 95% CI, 0.24-0.55; P < 0.001) and numerically favorable rwOS (HR, 0.46; 95% CI, 0.21-1.02; P = 0.0561). No differences were observed for HRDsig(-). mPARPi treatment interaction was observed for HRDsig(+) versus HRDsig(-) (rwPFS P < 0.001/rwOS P = 0.016) but not for BRCAalt versus BRCA-WT. Patients with BRCA-WT/HRDsig(+) receiving mPARPi had favorable rwPFS (HR, 0.40; 95% CI, 0.22-0.72; P = 0.003), whereas no difference was observed for BRCA-WT/HRDsig(-).

CONCLUSIONS

HRDsig predicted benefit of mPARPi better than BRCAalt. Patients with HRDsig(+) status experienced favorable outcomes, even if they had BRCA-WT status. In contrast, patients with HRDsig(-) status did not show significant benefit from mPARPi treatment. HRDsig might predict benefit from mPARPi regardless of BRCAalt status.

Single-Stranded DNA Gap Accumulation Is a Functional Biomarker for USP1 Inhibitor Sensitivity

Recent studies suggest that PARP and POLQ inhibitors confer synthetic lethality in BRCA1-deficient tumors by accumulation of single-stranded DNA (ssDNA) gaps at replication forks. Loss of USP1, a deubiquitinating enzyme, is also synthetically lethal with BRCA1 deficiency, and USP1 inhibitors are now undergoing clinical development for these cancers. Herein, we show that USP1 inhibitors also promote the accumulation of ssDNA gaps during replication in BRCA1-deficient cells, and this phenotype correlates with drug sensitivity. USP1 inhibition increased monoubiquitinated proliferating cell nuclear antigen at replication forks, mediated by the ubiquitin ligase RAD18, and knockdown of RAD18 caused USP1 inhibitor resistance and suppression of ssDNA gaps. USP1 inhibition overcame PARP inhibitor resistance in a BRCA1-mutated xenograft model and induced ssDNA gaps. Furthermore, USP1 inhibition was synergistic with PARP and POLQ inhibition in BRCA1-mutant cells, with enhanced ssDNA gap accumulation. Finally, in patient-derived ovarian tumor organoids, sensitivity to USP1 inhibition alone or in combination correlated with the accumulation of ssDNA gaps. Assessment of ssDNA gaps in ovarian tumor organoids represents a rapid approach for predicting response to USP1 inhibition in ongoing clinical trials. Significance: USP1 inhibitors kill BRCA1-deficient cells and cause ssDNA gap accumulation, supporting the potential of using ssDNA gap detection as a functional biomarker for clinical trials on USP1 inhibitors.

Prevalence and outcomes of germline pathogenic variants of homologous recombination repair genes in ovarian cancer

Germline pathogenic variants (PVs) are pivotal in gynecological oncology. We focused on the prevalence, clinicopathological features, and survival impact of homologous recombination repair (HRR) PVs in patients with epithelial ovarian cancer (EOC). This was a multicenter retrospective cohort study, and 1248 patients with EOC were registered. Eligible patients (n = 1112) underwent germline DNA analysis for 26 cancer predisposition genes, including nine HRR-related genes, such as BRCA1/2, BRIP1, PALB2, RAD51C/D, and ATM. The associations between clinicopathological factors and HRR-related PVs were examined. Kaplan-Meier and Cox regression analyses were conducted. Among 1091 analyzed patients, 153 (14.0%) carried PVs and 140 (12.8%) were HRR-related. HRR-PV-positive status significantly correlated with serous carcinoma (22.9% vs. 4.8%, P < 0.0001) and advanced disease (18.5% vs. 5.9%, P < 0.0001). The HRR-PV-positive group exhibited higher prevalence of personal breast (12.9%) and familial breast/ovarian (29.2%) cancer history. HRR status independently improved overall survival in stage III/IV disease (P = 0.04) but not progression-free survival. HRR-related germline PVs exhibit distinct clinicopathological features with survival implications. Variants were significantly associated with serous carcinoma and advanced disease, underscoring the importance of genetic testing to develop individualized EOC treatment strategies. Considering the study period (2000-2019), the limited use of bevacizumab and poly (ADP-ribose) polymerase inhibitors as maintenance therapy should be recognized.

Proapoptotic activity of JNK-sensitive BH3-only proteins underpins ovarian cancer response to replication checkpoint inhibitors

Recent studies indicate that replication checkpoint modulators (RCMs) such as inhibitors of CHK1, ATR, and WEE1 have promising monotherapy activity in solid tumors, including platinum-resistant high grade serous ovarian cancer (HGSOC). However, clinical response rates are generally below 30%. While RCM-induced DNA damage has been extensively examined in preclinical and clinical studies, the link between replication checkpoint interruption and tumor shrinkage remains incompletely understood. Here we utilized HGSOC cell lines and patient-derived xenografts (PDXs) to study events leading from RCM treatment to ovarian cancer cell death. These studies show that RCMs increase CDC25A levels and CDK2 signaling in vitro, leading to dysregulated cell cycle progression and increased replication stress in HGSOC cell lines independent of homologous recombination status. These events lead to sequential activation of JNK and multiple BH3-only proteins, including BCL2L11/BIM, BBC3/PUMA and the BMF, all of which are required to fully initiate RCM-induced apoptosis. Activation of the same signaling pathway occurs in HGSOC PDXs that are resistant to poly(ADP-ribose) polymerase inhibitors but respond to RCMs ex vivo with a decrease in cell number in 3-dimensional culture and in vivo with xenograft shrinkage or a significantly diminished growth rate. These findings identify key cell death-initiating events that link replication checkpoint inhibition to antitumor response in ovarian cancer.

ADC: a deadly killer of platinum resistant ovarian cancer

Platinum is a key component of ovarian cancer systemic therapy. However, most patients will eventually face a recurrence, leading to chemotherapy resistance, especially against platinum. For individuals with platinum-resistant ovarian cancer (PROC), treatment options are limited, and their survival prospects are grim. The emergence of antibody-drug conjugates (ADCs) shows promises as a future treatment for PROC. This review synthesizes current research on the effectiveness of ADCs in treating PROC. It encapsulates the advancements and clinical trials of novel ADCs that target specific antigens such as Folate Receptor alpha (FRα), MUC16, NaPi2b, Mesothelin, Dipeptidase 3(DPEP3), and human epidermal growth factor receptor 2 (HER2), as well as tissue factor, highlighting their potential anti-tumor efficacy and used in combination with other therapies. The ADCs landscape in ovarian cancer therapeutics is swiftly evolving, promising more potent and efficacious treatment avenues.

Olaparib Without Androgen Deprivation for High-Risk Biochemically Recurrent Prostate Cancer Following Prostatectomy: A Nonrandomized Controlled Trial

Importance

Olaparib is a poly(adenosine diphosphate-ribose) polymerase inhibitor that provides benefit in combination with hormonal therapies in patients with metastatic prostate cancer who harbor homologous recombination repair (HRR) alterations. Its efficacy in the absence of androgen deprivation therapy has not been tested.

Objective

To determine the activity of olaparib monotherapy among patients with high-risk biochemically recurrent (BCR) prostate cancer after radical prostatectomy.

Design, Setting, and Participants

This phase 2, single-arm nonrandomized controlled trial enrolled genetically unselected patients across 4 sites in the US from May 2017 to November 2022. Eligible patients had BCR disease following radical prostatectomy, a prostate-specific antigen (PSA) doubling time of 6 months or shorter, an absolute PSA value of 1.0 ng/mL or higher, and a testosterone level of 150 ng/dL or higher.

Intervention

Treatment was with olaparib, 300 mg, by mouth twice daily until doubling of the baseline PSA, clinical or radiographic progression, or unacceptable toxic effects.

Main Outcome and Measure

The primary end point was a confirmed 50% or higher decline in PSA from baseline (PSA50). Key secondary end points were outcomes by HRR alteration status, as well as safety and tolerability.

Results

Of the 51 male patients enrolled (mean [SD] age, 63.8 [6.8] years), 13 participants (26%) had a PSA50 response, all within the HRR-positive group (13 of 27 participants [48%]). All 11 participants with BRCA2 alterations experienced a PSA50 response. Common adverse events were fatigue in 32 participants (63%), nausea in 28 (55%), and leukopenia in 22 (43%), and were consistent with known adverse effects of olaparib.

Conclusions and Relevance

In this nonrandomized controlled trial, olaparib monotherapy led to high and durable PSA50 response rates in patients with BRCA2 alterations. Olaparib warrants further study as a treatment strategy for some patients with BCR prostate cancer but does not have sufficient activity in those without HRR alterations and should not be considered for those patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT03047135.

Strategies for the prevention or reversal of PARP inhibitor resistance

INTRODUCTION

Advances in our understanding of tumor biology shed light on hallmarks of cancer development and progression that include dysregulated DNA damage repair (DDR) machinery. Leveraging the underlying tumor genomic instability and tumor-specific defects in DDR, Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) induced DNA damage emerges as a novel non-chemotherapy therapeutic opportunity. PARPis are currently approved in multiple tumor types, with the largest benefit seen in tumors with homologous recombination repair (HRR) deficiency, including germline and somatic mutations in BRCA1/2 genes (BRCA) and other pathway members such as PALB2 and Rad51c.

AREAS COVERED

This review article summarizes the current approval landscape and known and proposed mechanisms of resistance to PARPi. Further, therapeutic strategies to overcome PARPi resistance are discussed, including ongoing clinical trials.

EXPERT OPINION

PARPi have proven to be a safe and effective therapy and represents a cornerstone treatment across multiple solid tumor types. Elucidating innate and acquired mechanisms of resistance, coupled with the emergence of novel therapeutic options to capitalize on the activity of PARPi and prevent or reverse the acquisition of resistance, provides an opportunity to further expand the role of PARPi in cancer therapy.

Extended panel testing in ovarian cancer reveals BRIP1 as the third most important predisposition gene

PURPOSE

The prevalence of germline pathogenic variants (PVs) in homologous recombination repair (HRR) and Lynch syndrome (LS) genes in ovarian cancer (OC) is uncertain.

METHODS

An observational study reporting the detection rate of germline PVs in HRR and LS genes in all OC cases tested in the North West Genomic Laboratory Hub between September 1996 and May 2024. Effect sizes are reported using odds ratios (ORs) and 95% confidence intervals (95% CI) for unselected cases tested between April 2021 and May 2024 versus 50,703 controls from the Breast Cancer Risk after Diagnostic Gene Sequencing study.

RESULTS

2934 women were tested for BRCA1/2 and 433 (14.8%) had a PV. In up to 1572 women tested for PVs in non-BRCA1/2 HRR genes, detection rates were PALB2 = 0.8%, BRIP1 = 1.1%, RAD51C = 0.4% and RAD51D = 0.4%. In 940 unselected cases, BRIP1 (OR = 8.7, 95% CI 4.6-15.8) was the third most common OC predisposition gene followed by RAD51C (OR = 8.3, 95% CI 3.1-23.1), RAD51D (OR = 6.5, 95% CI 2.1-19.7), and PALB2 (OR = 3.9, 95% CI 1.5-10.3). No PVs in LS genes were detected in unselected cases.

CONCLUSION

Panel testing in OC resulted in a detection rate of 2% to 3% for germline PVs in non-BRCA1/2 HRR genes, with the largest contributor being BRIP1. Screening for LS in unselected cases of OC is unnecessary.

Development and Perspectives: Multifunctional Nucleic Acid Nanomedicines for Treatment of Gynecological Cancers

Gynecological malignancies are a significant cause of morbidity and mortality across the globe. Due to delayed presentation, gynecological cancer patients are often referred late in the disease's course, resulting in poor outcomes. A considerable number of patients ultimately succumb to chemotherapy-resistant disease, which reoccurs at advanced stages despite treatment interventions. Although efforts have been devoted to developing therapies that demonstrate reduced resistance to chemotherapy and enhanced toxicity profiles, current clinical outcomes remain unsatisfactory due to treatment resistance and unfavorable off-target effects. Consequently, innovative biological and nanotherapeutic approaches are imperative to strengthen and optimize the therapeutic arsenal for gynecological cancers. Advancements in nanotechnology-based therapies for gynecological malignancies offer significant advantages, including reduced toxicity, expanded drug circulation, and optimized therapeutic dosing, ultimately leading to enhanced treatment effectiveness. Recent advances in nucleic acid therapeutics using microRNA, small interfering RNA, and messenger RNA provide novel approaches for cancer therapeutics. Effective single-agent and combinatorial nucleic acid therapeutics for gynecological malignancies have the potential to transform cancer treatment by giving safer, more tailored approaches than conventional therapies. This review highlights current preclinical studies that effectively exploit these approaches for the treatment of gynecological malignant tumors and malignant ascites.

DNA damage response in breast cancer and its significant role in guiding novel precise therapies

DNA damage response (DDR) deficiency has been one of the emerging targets in treating breast cancer in recent years. On the one hand, DDR coordinates cell cycle and signal transduction, whose dysfunction may lead to cell apoptosis, genomic instability, and tumor development. Conversely, DDR deficiency is an intrinsic feature of tumors that underlies their response to treatments that inflict DNA damage. In this review, we systematically explore various mechanisms of DDR, the rationale and research advances in DDR-targeted drugs in breast cancer, and discuss the challenges in its clinical applications. Notably, poly (ADP-ribose) polymerase (PARP) inhibitors have demonstrated favorable efficacy and safety in breast cancer with high homogenous recombination deficiency (HRD) status in a series of clinical trials. Moreover, several studies on novel DDR-related molecules are actively exploring to target tumors that become resistant to PARP inhibition. Before further clinical application of new regimens or drugs, novel and standardized biomarkers are needed to develop for accurately characterizing the benefit population and predicting efficacy. Despite the promising efficacy of DDR-related treatments, challenges of off-target toxicity and drug resistance need to be addressed. Strategies to overcome drug resistance await further exploration on DDR mechanisms, and combined targeted drugs or immunotherapy will hopefully provide more precise or combined strategies and expand potential responsive populations.

Targeting DNA damage response in pancreatic ductal adenocarcinoma: A review of preclinical and clinical evidence

Pancreatic ductal adenocarcinoma (PDAC) is associated with one of the most unfavorable prognoses across all malignancies. In this review, we investigate the role of inhibitors targeting crucial regulators of DNA damage response (DDR) pathways, either as single treatments or in combination with chemotherapeutic agents and targeted therapies in PDAC. The most prominent clinical benefit of PARP inhibitors' monotherapy is related to the principle of synthetic lethality in individuals harboring BRCA1/2 and other DDR gene mutations as predictive biomarkers. Moreover, induction of BRCAness with inhibitors of RTKs, including VEGFR and c-MET and their downstream signaling pathways, RAS/RAF/MEK/ERK and PI3K/AKT/mTOR in order to expand the application of PARP inhibitors in patients without DDR mutations, has also been addressed. Other DDR-targeting agents beyond PARP inhibitors, including inhibitors of ATM, ATR, CHEK1/2, and WEE1 have also demonstrated their potential in preclinical models of PDAC and may hold promise in future studies.

Predictive value of homologous recombination deficiency status for survival outcomes in primary tubo-ovarian high-grade serous carcinoma

OBJECTIVES

This is a protocol for a Cochrane Review (prognosis). The objectives are as follows: To evaluate the predictive value of the prognostic factor HRD status, as determined by various clinically validated HRD assays at the time of staging laparotomy, compared to BRCA1/2 mutation status for progression-free survival and overall survival in patients with tubo-ovarian high-grade serous carcinoma treated in the first-line setting with a combination of surgery and platinum-based chemotherapy and/or maintenance with PARP inhibitors.

Atezolizumab Combined With Platinum and Maintenance Niraparib for Recurrent Ovarian Cancer With a Platinum-Free Interval >6 Months: ENGOT-OV41/GEICO 69-O/ANITA Phase III Trial

PURPOSE

To evaluate atezolizumab combined with platinum-based chemotherapy (CT) followed by maintenance niraparib for late-relapsing recurrent ovarian cancer.

METHODS

The multicenter placebo-controlled double-blind randomized phase III ENGOT-OV41/GEICO 69-O/ANITA trial (ClinicalTrials.gov identifier: NCT03598270) enrolled patients with measurable high-grade serous, endometrioid, or undifferentiated recurrent ovarian cancer who had received one or two previous CT lines (most recent including platinum) and had a treatment-free interval since last platinum (TFIp) of >6 months. Patients were stratified by investigator-selected carboplatin doublet, TFIp, BRCA status, and PD-L1 status in de novo biopsy and randomly assigned 1:1 to receive either atezolizumab or placebo throughout standard therapy comprising six cycles of a carboplatin doublet followed (in patients with response/stable disease) by maintenance niraparib until progression. The primary end point was investigator-assessed progression-free survival (PFS) per RECIST v1.1.

RESULTS

Between November 2018 and January 2022, 417 patients were randomly assigned (15% BRCA-mutated, 36% PD-L1-positive, 66% TFIp >12 months, 11% previous poly [ADP-ribose] polymerase inhibitor after frontline CT, and 53% previous bevacizumab). Median follow-up was 28.6 months (95% CI, 26.6 to 30.5 months). Atezolizumab did not significantly improve PFS (hazard ratio, 0.89 [95% CI, 0.71 to 1.10]; P = .28). Median PFS was 11.2 months (95% CI, 10.1 to 12.1 months) with atezolizumab versus 10.1 months (95% CI, 9.2 to 11.2 months) with standard therapy. Subgroup analyses generally showed consistent results, including analyses by PD-L1 status. The objective response rate (ORR) was 45% (95% CI, 39 to 52) with atezolizumab and 43% (95% CI, 36 to 49) with standard therapy. The safety profile was as expected from previous experience of these drugs.

CONCLUSION

Combining atezolizumab with CT and maintenance niraparib for late-relapsing recurrent ovarian cancer did not significantly improve PFS or the ORR.

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.

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.

Phase 1b study of first-line fuzuloparib combined with modified FOLFIRINOX followed by fuzuloparib maintenance monotherapy in pancreatic adenocarcinoma

BACKGROUND

Chemotherapy remains the standard first-line treatment for pancreatic adenocarcinoma, but with limited efficacy. We aimed to explore the feasibility of adding the PARP inhibitor fuzuloparib to mFOLFIRINOX in the locally advanced/metastatic (LA/M) setting.

METHODS

This was the dose-escalation and -expansion, phase 1b portion of a phase 1b/2 study. Patients were given oral fuzuloparib at escalating doses starting at 30 mg twice daily (BID) plus intravenous mFOLFIRINOX q2w for 8-12 cycles, followed by maintenance fuzuloparib at 150 mg BID. Cohorts at the maximal tolerated dose (MTD) and lower dose of fuzuloparib were expanded. Primary endpoints were dose-limiting toxicity (DLT), MTD, and recommended phase 2 dose (RP2D).

RESULTS

As of data cutoff on Jan 15, 2023, 39 patients were recruited. 12 patients were enrolled during dose escalation (30 mg [n = 4]; 60 mg [n = 6]; 100 mg [n = 2]). DLT occurred in 1 patient in 60 mg cohort and 1 patient in 100 mg cohort. 60 mg BID was determined to be the MTD, and then 60 and 30 mg cohorts were expanded to 22 and 15 patients, respectively. The most common grade ≥ 3 treatment-related adverse events were hematologic toxicities. Efficacy in 60 mg cohort seemed to be most favorable, with an objective response rate of 50.0% (95% CI, 26.0-74.0) and disease control rate of 94.4% (95% CI, 72.7-99.9).

CONCLUSIONS

First-line fuzuloparib plus mFOLFIRINOX followed by maintenance fuzuloparib was generally safe and showed encouraging anti-tumor activity in patients with LA/M pancreatic adenocarcinoma. The RP2D of fuzuloparib combination was 60 mg BID.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04228601.

PARP inhibition with rucaparib alone followed by combination with atezolizumab: Phase Ib COUPLET clinical study in advanced gynaecological and triple-negative breast cancers

BACKGROUND

Combining PARP inhibitors (PARPis) with immune checkpoint inhibitors may improve clinical outcomes in selected cancers. We evaluated rucaparib and atezolizumab in advanced gynaecological or triple-negative breast cancer (TNBC).

METHODS

After identifying the recommended dose, patients with PARPi-naive BRCA-mutated or homologous recombination-deficient/loss-of-heterozygosity-high platinum-sensitive ovarian cancer or TNBC received rucaparib plus atezolizumab. Tumour biopsies were collected pre-treatment, during single-agent rucaparib run-in, and after starting combination therapy.

RESULTS

The most common adverse events with rucaparib 600 mg twice daily and atezolizumab 1200 mg on Day 1 every 3 weeks were gastrointestinal effects, fatigue, liver enzyme elevations, and anaemia. Responding patients typically had BRCA-mutated tumours and higher pre-treatment tumour levels of PD-L1 and CD8 + T cells. Markers of DNA damage repair decreased during rucaparib run-in and combination treatment in responders, but typically increased in non-responders. Apoptosis signature expression showed the reverse. CD8 + T-cell activity and STING pathway activation increased during rucaparib run-in, increasing further with atezolizumab.

CONCLUSIONS

In this small study, rucaparib plus atezolizumab demonstrated acceptable safety and activity in BRCA-mutated tumours. Increasing anti-tumour immunity and inflammation might be a key mechanism of action for clinical benefit from the combination, potentially guiding more targeted development of such regimens.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT03101280).

Efficacy and safety of rucaparib in patients with recurrent high-grade ovarian carcinoma: A systematic review and meta-analysis

Ovarian cancer stands as the third most prevalent gynecological malignancy. The advent of PARP inhibitors, particularly rucaparib, has revolutionized the landscape of advanced ovarian cancer treatment, demonstrating notable efficacy with minimal toxicity, especially in patients not previously exposed to PARP inhibitors. Rucaparib's precision-driven approach, targeting specific genetic mutations, disrupts DNA repair mechanisms, resulting in cytotoxic effects on neoplastic cells. This comprehensive review delves into the clinical efficacy and safety profile of rucaparib in recurrent ovarian cancer, showcasing its promising therapeutic approach. A systematic search of studies reporting rucaparib efficacy and safety, up to September 2023, was conducted across various reputable databases and sources. The meta-analysis of seven articles revealed a pooled objective response rate (ORR) of 0.331 (95% CI, 0.221-0.449; I2 = 92.4%), underscoring rucaparib's efficacy, particularly evident in the BRCA-mutated cohort. Rucaparib consistently outperformed controls in progression-free survival (PFS) and overall survival (OS). Safety evaluations indicated that 98.7% of patients experienced treatment-emergent adverse events (TEAEs), with 61% being grade ≥3. Notable TEAEs included nausea (69.0%), fatigue (66.8%), vomiting (37.3%), and constipation (32.1%). Hematological concerns comprised anemia (47.9%), thrombocytopenia, elevated AST/ALT (37.3%), and serum creatinine levels (19.7%). Despite favourable outcomes, the rucaparib group recorded higher event rates across various metrics than controls. The findings underscore the need for meticulous monitoring and dose adjustments to optimize therapeutic outcomes and mitigate the increased risks associated with adverse events. International Prospective Register of Systematic Review Identifier: CRD42023459646.

Niraparib in Japanese patients with platinum-sensitive recurrent ovarian cancer: final results of a multicenter phase 2 study

OBJECTIVE

This study evaluated the long-term safety and efficacy of niraparib in Japanese patients with platinum-sensitive recurrent ovarian cancer.

METHODS

This was a follow-up analysis of a phase 2, multicenter, open-label, single-arm study in Japanese women with platinum-sensitive, relapsed ovarian cancer. Participants received niraparib (starting dose 300 mg) once daily in continuous 28-day cycles. The primary endpoint was the incidence of Grade 3 or 4 thrombocytopenia-related events (defined as the overall incidence of the MedDRA Preferred Terms "thrombocytopenia" and "platelet count decreased") occurring in the 30 days after initial administration of niraparib, and secondary endpoints included evaluation of treatment-emergent adverse events and progression-free survival.

RESULTS

Nineteen patients (median age, 62 years; median body weight, 53.9 kg) were enrolled. As previously reported, the incidence of Grade 3 or 4 thrombocytopenia-related events during the first 30 days of treatment was 31.6%. At data cutoff, median (range) treatment exposure was 504.0 (56-1,054) days and mean ± standard deviation dose intensity was 154.4±77.5 mg/day. The most common treatment-emergent adverse events were nausea (n=14, 73.7%), decreased platelet count (n=12, 63.2%), decreased neutrophil count (n=11, 57.9%), anemia, vomiting, and decreased appetite (all n=9, 47.4%). One patient was diagnosed with treatment-related leukemia, which resulted in death. Median (95% confidence interval) progression-free survival was 18.0 (5.6-26.7) months.

CONCLUSION

Overall, the safety profile of niraparib was considered manageable in this study population of Japanese patients with platinum-sensitive, relapsed ovarian cancer and was consistent with that observed in studies of non-Japanese patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03759587.

Neoadjuvant talazoparib in patients with germline BRCA1/2 mutation-positive, early-stage triple-negative breast cancer: exploration of tumor BRCA mutational status

BACKGROUND

Talazoparib monotherapy in patients with germline BRCA-mutated, early-stage triple-negative breast cancer (TNBC) showed activity in the neoadjuvant setting in the phase II NEOTALA study (NCT03499353). These biomarker analyses further assessed the mutational landscape of the patients enrolled in the NEOTALA study.

METHODS

Baseline tumor tissue from the NEOTALA study was tested retrospectively using FoundationOne®CDx. To further hypothesis-driven correlative analyses, agnostic heat-map visualizations of the FoundationOne®CDx tumor dataset were used to assess overall mutational landscape and identify additional candidate predictive biomarkers of response.

RESULTS

All patients enrolled (N = 61) had TNBC. In the biomarker analysis population, 75.0% (39/52) and 25.0% (13/52) of patients exhibited BRCA1 and BRCA2 mutations, respectively. Strong concordance (97.8%) was observed between tumor BRCA and germline BRCA mutations, and 90.5% (38/42) of patients with tumor BRCA mutations evaluable for somatic-germline-zygosity were predicted to exhibit BRCA loss of heterozygosity (LOH). No patients had non-BRCA germline DNA damage response (DDR) gene variants with known/likely pathogenicity, based on a panel of 14 non-BRCA DDR genes. Ninety-eight percent of patients had TP53 mutations. Genomic LOH, assessed continuously or categorically, was not associated with response.

CONCLUSION

The results from this exploratory biomarker analysis support the central role of BRCA and TP53 mutations in tumor pathobiology. Furthermore, these data support assessing germline BRCA mutational status for molecular eligibility for talazoparib in patients with TNBC.

BRCA1, BRCA2, and Associated Cancer Risks and Management for Male Patients: A Review

Importance

Half of all carriers of inherited cancer-predisposing variants in BRCA1 and BRCA2 are male, but the implications for their health are underrecognized compared to female individuals. Germline variants in BRCA1 and BRCA2 (also known as pathogenic or likely pathogenic variants, referred to here as BRCA1/2 PVs) are well known to significantly increase the risk of breast and ovarian cancers in female carriers, and knowledge of BRCA1/2 PVs informs established cancer screening and options for risk reduction. While risks to male carriers of BRCA1/2 PVs are less characterized, there is convincing evidence of increased risk for prostate cancer, pancreatic cancer, and breast cancer in males. There has also been a rapid expansion of US Food and Drug Administration-approved targeted cancer therapies, including poly ADP ribose polymerase (PARP) inhibitors, for breast, pancreatic, and prostate cancers associated with BRCA1/2 PVs.

Observations

This narrative review summarized the data that inform cancer risks, targeted cancer therapy options, and guidelines for early cancer detection. It also highlighted areas of emerging research and clinical trial opportunities for male BRCA1/2 PV carriers. These developments, along with the continued relevance to family cancer risk and reproductive options, have informed changes to guideline recommendations for genetic testing and strengthened the case for increased genetic testing for males.

Conclusions and Relevance

Despite increasing clinical actionability for male carriers of BRCA1/2 PVs, far fewer males than female individuals undergo cancer genetic testing. Oncologists, internists, and primary care clinicians should be vigilant about offering appropriate genetic testing to males. Identifying more male carriers of BRCA1/2 PVs will maximize opportunities for cancer early detection, targeted risk management, and cancer treatment for males, along with facilitating opportunities for risk reduction and prevention in their family members, thereby decreasing the burden of hereditary cancer.

Synergistic Effects of PARP Inhibition and Cholesterol Biosynthesis Pathway Modulation

An in-depth multiomic molecular characterization of PARP inhibitors revealed a distinct poly-pharmacology of niraparib (Zejula) mediated by its interaction with lanosterol synthase (LSS), which is not observed with other PARP inhibitors. Niraparib, in a similar way to the LSS inhibitor Ro-48-8071, induced activation of the 24,25-epoxysterol shunt pathway, which is a regulatory signaling branch of the cholesterol biosynthesis pathway. Interestingly, the combination of an LSS inhibitor with a PARP inhibitor that does not bind to LSS, such as olaparib, had an additive effect on killing cancer cells to levels comparable with niraparib as a single agent. In addition, the combination of PARP inhibitors and statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, an enzyme catalyzing the rate-limiting step in the mevalonate pathway, had a synergistic effect on tumor cell killing in cell lines and patient-derived ovarian tumor organoids. These observations suggest that concomitant inhibition of the cholesterol biosynthesis pathway and PARP activity might result in stronger efficacy of these inhibitors against tumor types highly dependent on cholesterol metabolism.

SIGNIFICANCE

The presented data indicate, to our knowledge, for the first time, the potential benefit of concomitant modulation of cholesterol biosynthesis pathway and PARP inhibition and highlight the need for further investigation to assess its translational relevance.

Efficacy of chemotherapy after progression during or following PARPi exposure in ovarian cancer

BACKGROUND

Poly(ADP-ribose) polymerase inhibitors (PARPis) improved advanced ovarian cancer treatment. Most patients progress during or following PARPi exposure, however, with concerns about sensitivity of subsequent chemotherapy.

PATIENTS AND METHODS

In this international cohort study, we evaluated the efficacy of a subsequent chemotherapy following PARPi exposure in high-grade ovarian carcinoma patients. Endpoints included progression-free survival (PFS), overall survival and a multivariable Cox model was built to identify factors influencing PFS.

RESULTS

We included 291 patients from four international centers treated between January 2002 and December 2021. The median number of previous chemotherapy was 1 (1.0-7.0), the median duration of PARPi exposure was 6.5 months (0.2-54.3 months). PARPi was used in first line in 14.1% patients. Most progressions occurred under PARPi exposure (89.1%). A BRCA pathogenic variant was identified in 130 patients (44.7%), absent in 157 patients (54.0%), and undocumented in 4 patients (1.4%). Platinum-based CT (PBC) and non-PBC were administered as subsequent treatments in, respectively, 182 patients (62.5%) and 109 patients (37.5%). Multivariable analyses showed that platinum-free interval (PFI) >6 months [adjusted hazards ratio (HR), 0.52; 95% confidence interval (CI) 0.39-0.70] and type of initial surgery (adjusted HR, 1.41; 95% CI 1.07-1.87; interval or closing surgery versus primary surgery) were associated with PFS, independent of BRCA status or line of therapy (≥2 versus 1). In patients with a PFI >6 months, PBC was numerically associated with the best PFS (adjusted HR, 0.68; 95% CI 0.46-1.01).

CONCLUSION

This is the largest real-world study assessing the efficacy of subsequent chemotherapy in patients progressing during PARPi exposure. The patients have poor outcomes. PBC is the best option in patients progressing on PARPi and eligible for PBC rechallenge (PFI >6 months).

The paradigm shift in advanced ovarian cancer: Outcomes of extensive primary cytoreductive surgery. A single-center retrospective analysis

OBJECTIVE

The standard surgical treatment of advanced ovarian carcinoma is primary debulking surgery (PDS) aiming to complete cytoreduction. The need to achieve complete cytoreduction has shifted the surgical paradigm to more complex procedures, whose impact on morbidity is controversial. The objective of this retrospective analysis is to explore the impact of extensive PDS on morbidity and oncologic outcomes in a real-world scenario.

METHODS

A retrospective single-center analysis was performed on 137 patients with advanced high-grade ovarian carcinoma (HGOC) who received PDS in 2015-2020. Patients treated in 2015-2017 (Group 1) were compared to patients treated in 2018-2020 (Group 2). The two periods were chosen according to the higher complexity of surgical procedures introduced in 2018.

RESULTS

The increase in complete cytoreduction observed in Group2 (RD 0: 33 % vs 61 %, p = 0,008) was related to a higher surgical complexity (Aletti Score: 4 vs 6, p = 0,003) and did not reflect an increase in peri-operative complications (CCI: 20,9 vs 20,9, p = 0,11). After a median FUP of 44 months, PFS and OS at 24 months were 33,60 % vs 47,33 % (p = 0,288) and 72,10 % vs 80,37 % (p = 0,022) in Group 1 and 2, respectively.

CONCLUSIONS

An extensive surgical effort leads to a significant increase in complete cytoreduction with acceptable morbidity. Arm-in-arm with novel maintenance therapies, it contributes to increasing the outcomes of patients with advanced HGOC.

The treatment landscape of triple-negative breast cancer

Triple-negative breast cancer (TNBC) tumors are biologically aggressive breast cancer. On the molecular level, TNBC is a highly heterogeneous disease; more biotechnologies are gradually being used to advance the understanding of TNBC subtypes and help establish more targeted therapies. Multiple TNBC target-related agents are already approved by the Food and Drug Administration for clinical use, including PI3K/AKT/mTOR inhibitors, PRAP inhibitors, and antibody-drug conjugates. Some innovative approaches, like peptide strategies, also promise to treat TNBC. Currently, the interplay between TNBC tumors and their tumor microenvironment provides a promising prospect for improving the efficacy of immunotherapy. In this review, we summarize the prevalent TNBC subtype methodologies, discuss the evolving therapeutic strategies, and propose new therapeutic possibilities based on existing foundational theories, with the attempt to serve as a reference to further advance tailoring treatment of TNBC.

Molecular biology as a driver in therapeutic choices for ovarian cancer

The majority of patients with ovarian cancer relapse within 3 years of first line chemotherapy. Therefore, choosing the most appropriate treatment in the recurrence setting has a fundamental role in defining a patient's prognosis. Treatment options include systemic and intra-peritoneal chemotherapy, secondary cytoreductive surgery, and stereotactic body radiotherapy. The best therapeutic choice depends on multiple factors and not only on treatment-free interval. For systemic therapy, prior lines therapy, residual toxicities, comorbidities, performance status, and patient preferences should be taken into account. Secondary cytoreductive surgery can be proposed in patients in which complete tumor resectability can be predicted and in those with oligometastatic disease. Stereotactic body radiotherapy represents a valid alternative to surgery for oligometastatic disease with high local control and minimal toxicity. Current evidence has demonstrated an emerging role of BRCA mutational status and molecular profiling in the impacting response to systemic and local treatments. Therefore, these could provide guidance in the treatment decision process and help identify patients who respond better to poly(ADP-ribose) polymerase (PARP)-inhibitors or immunotherapy or to a combined approach with surgery rather than to platinum-based chemotherapy. Current knowledge in this field could help widen therapeutic options, especially for platinum-resistant patients. In this review, we offer an overview of the state of the art regarding the role of chemotherapy, radiotherapy, and surgery in this setting and their implications in clinical practice and in the treatment decision process, so as to provide the best tailored therapy in patients with recurrent ovarian cancer.

The PARP1 selective inhibitor saruparib (AZD5305) elicits potent and durable antitumor activity in patient-derived BRCA1/2-associated cancer models

BACKGROUND

Poly (ADP-ribose) polymerase 1 and 2 (PARP1/2) inhibitors (PARPi) are targeted therapies approved for homologous recombination repair (HRR)-deficient breast, ovarian, pancreatic, and prostate cancers. Since inhibition of PARP1 is sufficient to cause synthetic lethality in tumors with homologous recombination deficiency (HRD), PARP1 selective inhibitors such as saruparib (AZD5305) are being developed. It is expected that selective PARP1 inhibition leads to a safer profile that facilitates its combination with other DNA damage repair inhibitors. Here, we aimed to characterize the antitumor activity of AZD5305 in patient-derived preclinical models compared to the first-generation PARP1/2 inhibitor olaparib and to identify mechanisms of resistance.

METHODS

Thirteen previously characterized patient-derived tumor xenograft (PDX) models from breast, ovarian, and pancreatic cancer patients harboring germline pathogenic alterations in BRCA1, BRCA2, or PALB2 were used to evaluate the efficacy of AZD5305 alone or in combination with carboplatin or an ataxia telangiectasia and Rad3 related (ATR) inhibitor (ceralasertib) and compared it to the first-generation PARPi olaparib. We performed DNA and RNA sequencing as well as protein-based assays to identify mechanisms of acquired resistance to either PARPi.

RESULTS

AZD5305 showed superior antitumor activity than the first-generation PARPi in terms of preclinical complete response rate (75% vs. 37%). The median preclinical progression-free survival was significantly longer in the AZD5305-treated group compared to the olaparib-treated group (> 386 days vs. 90 days). Mechanistically, AZD5305 induced more replication stress and genomic instability than the PARP1/2 inhibitor olaparib in PARPi-sensitive tumors. All tumors at progression with either PARPi (39/39) showed increase of HRR functionality by RAD51 foci formation. The most prevalent resistance mechanisms identified were the acquisition of reversion mutations in BRCA1/BRCA2 and the accumulation of hypomorphic BRCA1. AZD5305 did not sensitize PDXs with acquired resistance to olaparib but elicited profound and durable responses when combined with carboplatin or ceralasertib in 3/6 and 5/5 models, respectively.

CONCLUSIONS

Collectively, these results show that the novel PARP1 selective inhibitor AZD5305 yields a potent antitumor response in PDX models with HRD and delays PARPi resistance alone or in combination with carboplatin or ceralasertib, which supports its use in the clinic as a new therapeutic option.

Neurological toxicities with poly (ADP-ribose) polymerase inhibitors in cancer patients: a systematic review and meta-analysis

We conducted this meta-analysis to investigate neurological toxicities with poly (ADP-ribose) polymerase inhibitors (PARPis) in cancer patients. Databases were searched for randomized controlled trials (RCTs) from 1 January 2000 to 1 November 2023. Forty-six RCTs and 9529 patients were included. PARPis could increase the risk of all-grade headache [risk ratio (RR), 1.22; 95% confidence intervals (CI), 1.14-1.30; P < 0.00001], dizziness (RR, 1.40; 95% CI, 1.28-1.53; P < 0.00001), dysgeusia (RR, 1.93; 95% CI, 1.44-2.60; P < 0.0001) and insomnia (RR, 1.32; 95% CI, 1.09-1.60; P < 0.0001) in cancer patients. Headache was the most common neurological toxicity. Niraparib was associated with a higher risk of headache and insomnia, talazoparib with a higher risk of dizziness and rucaparib with a higher risk of dysgeusia. Breast cancer patients receiving PARPis have a higher risk of dysgeusia, while ovarian cancer patients are at an increased risk of insomnia. PARPis may increase the risk of mild to moderate neurological toxicities, but not severe ones.

Exploring the impact of BRCA1 and BRCA2 mutation type and location on Olaparib maintenance therapy in platinum-sensitive relapsed ovarian Cancer patients: A single center report

OBJECTIVE

In patients with platinum-sensitive relapsed ovarian cancer (PSROC) harboring pathogenic/likely pathogenic variants (PV) in BRCA1 and BRCA2 genes, olaparib maintenance monotherapy (OMT) is a viable option. Our study aimed to evaluate the impact of different BRCA1/2 PV in survival outcomes and safety of OMT in BRCA1/2-mutated PSROC patients, focusing on the type and location of PV.

METHODS

We assessed the outcomes of 100 BRCA1/2-mutated PSROC patients treated at our institute, analyzing progression-free survival (PFS) and overall survival (OS). Germline and tumor BRCA1/2 genotyping was conducted using Illumina's next-generation sequencing (NGS).

RESULTS

PFS and OS were significantly shorter in PSROC patients with PV in BRCA1 compared to those with PV in BRCA2 (PFS:14.0 vs. 38.8 months, p = 0.007, OS: 21.8 vs. 62.0 months, p = 0.011). Notably, there was a significant difference in PFS based on the intragenic location of BRCA1 PV, with shorter PFS in patients with 1st/2nd relapse, harboring PV in BRCA1 RING domain compared to those with PV in the DNA binding domain (DBD) and BRCT domains (12.4 vs. 23.0 months, p = 0.046). No differences in PFS and OS were observed between patients with germline versus somatic BRCA1/2 PV (PFS:14.9 vs.19.3, p = 0.316, OS: not reached vs. 25.8 months; p = 0.224). However, there were significant differences in the reasons for OMT discontinuation between patients with germline and somatic BRCA1/2 PV, primarily due to adverse side effects.

CONCLUSIONS

In summary, the type and location of BRCA1 and BRCA2 PV provide additional insight into the expected survival outcomes of olaparib MT in PSROC patients.

TRIAL REGISTRATION NUMBER

ISRCTN42408038, Name of registry: ISRCTN registry, Date of registration: 24/11/2015.

Application of PARP inhibitors combined with immune checkpoint inhibitors in ovarian cancer

The advent of polyadenosine diphosphate ribose polymerase inhibitors (PARPi) has brought about significant changes in the field of ovarian cancer treatment. However, in 2022, Rucaparib, Olaparib, and Niraparib, had their marketing approval revoked for third-line and subsequent therapies due to an increased potential for adverse events. Consequently, the exploration of new treatment modalities remains imperative. Recently, the integration of PARPi with immune checkpoint inhibitors (ICIs) has emerged as a potential remedy option within the context of ovarian cancer. This article offers a comprehensive examination of the mechanisms and applications of PARPi and ICIs in the treatment of ovarian cancer. It synthesizes the existing evidence supporting their combined use and discusses key considerations that merit attention in ongoing development efforts.

Detection and analysis of the safety profile of talazoparib based on FAERS database

BACKGROUND

Talazoparib was approved for the treatment of breast cancer. However, the safety of talazoparib in a large population sample over an extended period remained uncertain. The objective of this study is to offer guidance for the secure utilization of talazoparib in clinical settings.

METHODS

Four algorithms were used to quantify the signals of talazoparib associated adverse events(AEs), using data from the food and drug administration adverse event reporting system(FAERS) between fourth quater of 2018 and second quater of 2023.

RESULTS

A total of 7,186,517 records were reported, with 737 indicating talazoparib as the primary suspected (PS) AEs. A total of 40 significant preferred terms (PTs) that adhere to the four algorithms were simultaneously retained. There is a possibility of experiencing unforeseen and noteworthy AEs, including embolism(0.46%), pulmonary embolism(1.06%), hyponatremia(0.46%), hypokalemia(0.40%), hematuria(0.33%), and pericardial effusion(0.26%). Most of the AEs related to talazoparib occurred within the initial month of starting the medication, with a median onset time of 79 days (IQR: 22-207 days).

CONCLUSION

Results of our study were consistent with clinical observations, and we also found potential new and unexpected AEs signals for talazoparib, suggesting prospective clinical studies were needed to confirm these results and illustrate their relationship. Our results may provide valuable evidence for further safety studies of talazoparib.

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

BACKGROUND

RAD51C and RAD51D are crucial in homologous recombination (HR) DNA repair. The prevalence of the RAD51C and RAD51D mutations in breast cancer varies across ethnic groups. Associations of RAD51C and RAD51D germline pathogenic variants (GPVs) with breast and ovarian cancer predisposition have been recently reported and are of interest.

METHODS

We performed multi-gene panel sequencing to study the prevalence of RAD51C and RAD51D germline mutations among 3728 patients with hereditary breast and/or ovarian cancer (HBOC).

RESULTS

We identified 18 pathogenic RAD51C and RAD51D mutation carriers, with a mutation frequency of 0.13% (5/3728) and 0.35% (13/3728), respectively. The most common recurrent mutation was RAD51D c.270_271dupTA; p.(Lys91Ilefs*13), with a mutation frequency of 0.30% (11/3728), which was also commonly identified in Asians. Only four out of six cases (66.7%) of this common mutation tested positive for homologous recombination deficiency (HRD).

CONCLUSIONS

Taking the family studies in our registry and tumor molecular pathology together, we concluded that this relatively common RAD51D variant showed incomplete penetrance in our local Chinese community. Personalized genetic counseling emphasizing family history for families with this variant, as suggested at the UK Cancer Genetics Group (UKCGG) Consensus meeting, would also be appropriate in Chinese families.

Current HRD assays in ovarian cancer: differences, pitfalls, limitations, and novel approaches

Ovarian carcinoma (OC) still represents an insidious and fatal malignancy, and few significant results have been obtained in the last two decades to improve patient survival. Novel targeted therapies such as poly (ADP-ribose) polymerase inhibitors (PARPi) have been successfully introduced in the clinical management of OC, but not all patients will benefit, and drug resistance almost inevitably occurs. The identification of patients who are likely to respond to PARPi-based therapies relies on homologous recombination deficiency (HRD) tests, as this condition is associated with response to these treatments. This review summarizes the genomic and functional HRD assays currently used in clinical practice and those under evaluation, the clinical implications of HRD testing in OC, and their current pitfalls and limitations. Special emphasis will be placed on the functional HRD assays under development and the use of machine learning and artificial intelligence technologies as novel strategies to overcome the current limitations of HRD tests for a better-personalized treatment to improve patient outcomes.

Polθ: emerging synthetic lethal partner in homologous recombination-deficient tumors

The most remarkable finding in synthetic lethality (SL) is the hypersensitivity to PARP inhibitors (PARPis) of the tumors harboring defects in genes involved in homologous repair (HR) such as BRCA1/2. Despite initial responsiveness to PARPi, the penetrance of the synthetic lethal interactions between BRCA1/2 genes and PARPi is incomplete. Thus, a significant proportion of HR-defective tumors experience intrinsic or acquired resistance, representing a key challenge of clinical research. An expanded concept of SL is opening new ways and includes novel forms of genetic interactions, investigating not only traditional SL of pairs genes but also SL between biological pathways that regulate the same essential survival cell function. In this context, recent research showed that HR and theta-mediated end-joining (TMEJ) pathways exhibit SL. DNA polymerase theta (Polθ) is encoded by the POLQ gene and is a key component of the TMEJ, an essential backup pathway, intrinsically mutagenic, to repair resected double-strand breaks (DSBs) when the non-homologous end joining (NHEJ) and HR are impaired. Polθ is broadly expressed in normal tissues, overexpressed in several cancers, and typically associated with poor outcomes and shorter relapse-free survival. Notably, HR-deficient tumor cells present the characteristic mutational signatures of the error-prone TMEJ pathway. According to this observation, the loss of HR proteins, such as BRCA1 or BRCA2, contributes to increasing the TMEJ-specific genomic profile, suggesting synthetic lethal interactions between loss of the POLQ and HR genes, and resulting in the emerging interest for Polθ as a potential therapeutic target in BRCA1/2-associated tumors.This review summarizes the converging roles of the POLQ and HR genes in DNA DSB repair, the early-stage clinical trials using Polθ inhibitor to treat HR-defective tumors and to overcome BRCA-reversion mutations responsible for therapeutic resistance, and the novel pleiotropic effects of Polθ, paving the way for the development of unexplored synthetic lethality strategies.

Role of poly-ADP-ribose polymerase inhibitors after brain progression in platinum-sensitive ovarian cancer: a case report and review of the literature

Introduction

The incidence of brain metastases in ovarian cancer is quite rare, being approximately 1%-2%. According to retrospective studies, patients with BRCA 1/2 mutations present a higher risk. The trimodal approach based on surgery, radiotherapy, and chemotherapy presents better outcomes, but the prognosis remains poor with overall survival since the brain progression is around 1 year. Poly-ADP-ribose polymerase inhibitors (PARPi) have provided a new alternative for the management of advanced ovarian cancer. The SOLO2, NOVA, and ARIEL3 clinical trials do not refer data on patients with brain metastases, and the published evidence for PARPi in this setting comes only from case reports and retrospective studies.

Case report

We present the case of a 54-year-old woman with stage IV ovarian high-grade serous papillary carcinoma who, after 37 months of treatment with olaparib, presented a single brain lesion. After radical treatment with surgery and adjuvant whole-brain radiotherapy, she resumed olaparib with no evidence of disease during 15 months. After a second single brain relapse treated with stereotactic radiosurgery, the patient continued olaparib beyond the brain progression with no evidence of extracranial disease. Despite that there were no changes in size or number of brain lesions, the neurological situation progressively worsened and the patient died 8 months after the second progression.

Discussion

The higher incidence of brain metastases of ovarian cancer points out a possible tropism for the CNS in BRCA-mutated patients. In preclinical studies, PARPi has shown to cross the blood-brain barrier, with possible antitumor activity in the central nervous system (CNS) while maintaining control of extracranial disease. The best survival data are obtained with a trimodal approach, and adding a PARPi could improve the survival outcomes in the context of platinum-sensitivity disease. Targeted therapies combined with local treatments are also used in other malignancies, suggesting potential effectiveness due to tumor heterogeneity. PARPi before brain metastasis may delay its diagnosis, and using iPARP after brain metastases could improve the outcome of this population.

Conclusion

The role that PARPi may have in the treatment of brain metastases of ovarian cancer requires more studies. In the context of radical treatment of brain metastasis (surgery and/or RT), with no evidence of extracranial disease, maintaining treatment with PARPi beyond the brain progression should be considered.

Biomarkers for Precision Patient Selection in Cancer Therapy Approvals in the US, from 2011 to 2023

During the period of 2011-2023, the US Food and Drug Administration (US FDA) granted 139 accelerated and 329 regular approvals for 86 and 152 cancer therapeutic products, respectively. The percentage of approvals for a biomarker-defined population was numerically higher in accelerated approvals in comparison to regular approvals, that is, 48% vs. 40%. From 2011-2016 to 2017-2023, there was an increasing number of approvals with biomarker-defined populations in lung and breast cancers, serving as the primary driver for the overall increase in the percentage of approvals for biomarker-defined populations in solid tumors relative to hematological malignancies. Over the years, approvals were incorporating a more diverse collection of distinct biomarkers, from 3 in 2011 to 16 in 2022. Overall, HER2, hormone receptor (HR), EGFR, ALK, BRAF, and PD-L1-defined populations received the highest numbers of approvals. The FDA decision on approving a biomarker-defined or an all-comers population may depend on a number of factors and may evolve over time based on emerging evidence. The review discusses selected FDA approvals where a pivotal trial enrolled an all-comers population but the approved indication was restricted to a biomarker-defined population, as well as challenges in clinical trial design in the context of precision medicine. The prominent role of biomarkers in optimizing trial design and identifying a population most likely to benefit from treatment underlines the significance of a comprehensive understanding of disease biology and drug mechanisms. Our review illustrates that biomarker-driven approaches enhance the likelihood of identifying optimal patient populations, potentially streamlining trials through accelerated approval pathways for cancer drug development.

Germline Genetic Testing for Hereditary Breast and Ovarian Cancer: Current Concepts in Risk Evaluation

Our understanding of hereditary breast and ovarian cancer has significantly improved over the past two decades. In addition to BRCA1/2, pathogenic variants in several other DNA-repair genes have been shown to increase the risks of breast and ovarian cancer. The magnitude of cancer risk is impacted not only by the gene involved, but also by family history of cancer, polygenic risk scores, and, in certain genes, pathogenic variant type or location. While estimates of breast and ovarian cancer risk associated with pathogenic variants are available, these are predominantly based on studies of high-risk populations with young age at diagnosis of cancer, multiple primary cancers, or family history of cancer. More recently, breast cancer risk for germline pathogenic variant carriers has been estimated from population-based studies. Here, we provide a review of the field of germline genetic testing and risk evaluation for hereditary breast and ovarian cancers in high-risk and population-based settings.

Trends in estimated PARP inhibitor eligibility and benefit among US epithelial ovarian cancer patients

OBJECTIVE

To estimate the annual percentage of patients with epithelial ovarian cancer (EOC) who could be eligible for and benefit from PARP inhibitor therapy amidst changing US Food and Drug Administration (FDA)-approved indications.

METHODS

This is a simulated retrospective observational study using publicly available data on patients with advanced-stage EOC. PARPi eligibility is based on FDA approvals and withdrawals from 2014 through 2023, along with published demographic and genomic data. Clinical trial data is used to estimate treatment benefit. PARPi including olaparib, niraparib, and rucaparib are analyzed in aggregate with sub-analyses by molecular classification and treatment timing. Results are reported as the percentage of EOC patients appropriate for any cancer-directed therapy.

RESULTS

PARPi were approved for 9 different indications in EOC between 2014 and 2021; reduced to 6 indications by 2023. Eligibility increased from 2.0% (95% CI,1.3%-1.6%) in 2014 to a maximum of 93.4% (95% CI,90.1%-94.6%) in 2021. The maximum percentage of patients with 2-year PFS benefit was 22.0% (95% CI, 17.2%-26.8%) in 2021, projected to decrease to 13.0% (95% CI, 9.9%-15.9%) in 2024. Most of this decrease was seen in the homologous recombination deficient, BRCA wild-type population (8.4% to 4.0%).

CONCLUSIONS

PARPi eligibility increased at a greater rate than benefit resulting in a low population-level benefit-to-eligibility ratio until 2021. Recent FDA withdrawals improved this ratio with an accompanied decrease in the absolute number of patients benefiting. To further optimize population-level benefit-to-eligibility ratio of targeted therapies in ovarian cancer, we need to identify better biomarkers, treatment combinations, and novel therapeutic targets.

Targeted therapy in high grade serous ovarian Cancer: A literature review

Ovarian cancer continues to have a high mortality rate despite therapeutic advances. Traditionally, treatment has focused on surgery followed by systemic platinum- based chemotherapy. Unfortunately, most patients develop resistance to platinum agents, highlighting the need for targeted therapies. PARP inhibitors and anti-angiogenic agents, such as bevacizumab, have more recently changed upfront therapy. Unfortunately, other targeted therapies including immunotherapy have not seen the same success. Emerging therapeutic targets and modalities such as small molecule tyrosine kinase inhibitors, lipid metabolism targeting agents, gene therapy, ribosome targeted drugs as well as several other therapeutic classes have been and are currently under investigation. In this review, we discuss targeted therapies in high grade serous ovarian cancer from preclinical studies to phase III clinical trials.

Untapped Potential of Poly(ADP-Ribose) Polymerase Inhibitors: Lessons Learned From the Real-World Clinical Homologous Recombination Repair Mutation Testing

Background

Testing for homologous recombination deficiency (HRD) mutations is pivotal to assess individual risk, to proact preventive measures in healthy carriers and to tailor treatments for cancer patients. Increasing prominence of poly(ADP-ribose) polymerase (PARP) inhibitors with remarkable impact on molecular-selected patient survival across diverse nosologies, ingrains testing for BRCA genes and beyond in clinical practice. Nevertheless, testing strategies remain a question of debate. While several pathogenic BRCA1/2 gene variants have been described as founder pathogenic mutations frequently found in patients from Russia, other homologous recombination repair (HRR) genes have not been sufficiently explored. In this study, we present real-world data of routine HRR gene testing in Russia.

Methods

We evaluated clinical and sequencing data from cancer patients who had germline/somatic next-generation sequencing (NGS) HRR gene testing in Russia (BRCA1/2/ATM/CHEK2, or 15 HRR genes). The primary objectives of this study were to evaluate the frequency of BRCA1/2 and non-BRCA gene mutations in real-world unselected patients from Russia, and to determine whether testing beyond BRCA1/2 is feasible.

Results

Data of 2,032 patients were collected from February 2021 to February 2023. Most had breast (n = 715, 35.2%), ovarian (n = 259, 12.7%), pancreatic (n = 85, 4.2%), or prostate cancer (n = 58, 2.9%). We observed 586 variants of uncertain significance (VUS) and 372 deleterious variants (DVs) across 487 patients, with 17.6% HRR-mutation positivity. HRR testing identified 120 (11.8%) BRCA1/2-positive, and 172 (16.9%) HRR-positive patients. With 51 DVs identified in 242 formalin-fixed paraffin-embedded (FFPE), testing for variant origin clarification was required in one case (0.4%). Most BRCA1/2 germline variants were DV (121 DVs, 26 VUS); in non-BRCA1/2 genes, VUS were ubiquitous (53 DVs, 132 VUS). In silico prediction identified additional 4.9% HRR and 1.2% BRCA1/2/ATM/CHEK2 mutation patients.

Conclusions

Our study represents one of the first reports about the incidence of DV and VUS in HRR genes, including genes beyond BRCA1/2, identified in cancer patients from Russia, assessed by NGS. In silico predictions of the observed HRR gene variants suggest that non-BRCA gene testing is likely to result in higher frequency of patients who are candidates for PARP inhibitor therapy. Continuing sequencing efforts should clarify interpretation of frequently observed non-BRCA VUS.

A phase 2 trial exploring the significance of homologous recombination status in patients with platinum sensitive or platinum resistant relapsed ovarian cancer receiving combination cediranib and olaparib

OBJECTIVE

Combination cediranib/olaparib has reported activity in relapsed ovarian cancer. This phase 2 trial investigated the activity of cediranib/olaparib in relapsed ovarian cancer and its association with homologous recombination deficiency (HRD).

METHODS

Seventy patients were enrolled to cohorts of either platinum-sensitive or platinum-resistant ovarian cancer and received olaparib tablets 200 mg twice daily and cediranib tablets 30 mg once daily under a continuous dosing schedule. HRD testing was performed on pre-treatment, on-treatment and archival biopsies by sequencing key homologous recombination repair (HRR) genes and by genomic LOH analysis. The primary objective for the platinum-sensitive cohort was the association of HRD, defined as presence of HRR gene mutation, with progression-free survival (PFS). The primary objective for the platinum-resistant cohort was objective response rate (ORR), with a key secondary endpoint evaluating the association of HRD status with activity.

RESULTS

In platinum-sensitive ovarian cancer (N = 35), ORR was 77.1% (95% CI 59.9-89.6%) and median PFS was 16.4 months (95% CI 13.2-18.6). Median PFS in platinum-sensitive HRR-HRD cancers (N = 22) was 16.8 months (95% CI 11.3-18.6), and 16.4 months (95% CI 9.4-NA) in HRR-HR proficient cancers (N = 13; p = 0.57). In platinum-resistant ovarian cancer (N = 35), ORR was 22.9% (95% CI 10.4-40.1%) with median PFS 6.8 months (95% CI 4.2-9.1). Median PFS in platinum-resistant HRR-HRD cancers (N = 7) was 10.5 months (95% CI 3.6-NA) and 5.6 months (95% CI 3.6-7.6) in HRR-HR proficient cancers (N = 18; p = 0.23).

CONCLUSIONS

Cediranib/olaparib had clinical activity in both platinum-sensitive and -resistant ovarian cancer. Presence of HRR gene mutations was not associated with cediranib/olaparib activity in either setting.

Targeted Nanocarrier-Based Drug Delivery Strategies for Improving the Therapeutic Efficacy of PARP Inhibitors against Ovarian Cancer

The current focus of ovarian cancer (OC) research is the improvement of treatment options through maximising drug effectiveness. OC remains the fifth leading cause of cancer-induced mortality in women worldwide. In recent years, nanotechnology has revolutionised drug delivery systems. Nanoparticles may be utilised as carriers in gene therapy or to overcome the problem of drug resistance in tumours by limiting the number of free drugs in circulation and thereby minimising undesired adverse effects. Cell surface receptors, such as human epidermal growth factor 2 (HER2), folic acid (FA) receptors, CD44 (also referred to as homing cell adhesion molecule, HCAM), and vascular endothelial growth factor (VEGF) are highly expressed in ovarian cancer cells. Generation of active targeting nanoparticles involves modification with ligands that recognise cell surface receptors and thereby promote internalisation by cancer cells. Several poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) are currently used for the treatment of high-grade serous ovarian carcinomas (HGSOC) or platinum-sensitive relapsed OC. However, PARP resistance and poor drug bioavailability are common challenges, highlighting the urgent need to develop novel, effective strategies for ovarian cancer treatment. This review evaluates the utility of nanoparticles in ovarian cancer therapy, with a specific focus on targeted approaches and the use of PARPi nanocarriers to optimise treatment outcomes.

Past and present: a bibliometric study on the treatment of recurrent ovarian cancer

Background

Ovarian cancer (OC) is a gynecological malignancy with a high mortality rate worldwide. The unfavorable prognosis of OC is mainly attributed to the recurrent propensity. Recently, mortality from OC has exhibited a downward trend. These favorable patterns are likely to be driven by advancements in novel therapeutic regimens. However, there is a lack of visualize analysis of the application of these new drugs on women with recurrent OC (ROC). Therefore, we aimed to provide a bibliometric analysis of the evolving paradigms in the ROC treatment.

Methods

Documents on ROC treatment were systematically collected from the MEDLINE database and Web of Science Core Collection (WOSCC). The retrieved documents were exported in the plain text file format, and files were named and saved to the paths specified by the Java application. Microsoft Excel (version 2010), Citespace (6.2.R4) and VOSviewer (1.6.19) were used for data analysis, and included the following: 1) annual publication trend; 2) contributions of countries, institutions and authors; 3) co-citation of journals and references; and 4) co-occurrence of keywords.

Results

A total of 914 documents published in the MEDLINE and 9,980 ones in WOSCC were retrieved. There has been an upward trend in the productivity of publications on ROC treatment on by years. The United States was the leading contributor in this field, and the University of Texas System stood out as the most productive institution. Giovanni Scambia and Maurie Markman were the research leaders in the field of ROC treatment. The journal Gynecologic Oncology had the highest citation frequency. The reference entitled with "Niraparib Maintenance Therapy in Platinum-Sensitive, Recurrent Ovarian Cancer" got highest centrality of 0.14 in the co-citation network. Keyword analysis revealed that the focus of current ROC treatment was on platinum-based anticancer drugs, paclitaxel, angiogenesis inhibitors (AIs), immune checkpoint inhibitors (ICIs) and poly (ADP-ribose) polymerase inhibitors (PARPis).

Conclusion

Scholars from a multitude of countries have been instrumental in the advancement of ROC treatment. The research hotspots and trend in the field of predominantly originated from leading international journals and specialized periodicals focused on gynecologic oncology. Maintenance therapy using AIs or (and) PARPis has emerged as a significant complement to platinum-based chemotherapy for patients with ROC.

Poly (ADP-ribose) polymerase inhibitor therapy and mechanisms of resistance in epithelial ovarian cancer

Advanced epithelial ovarian cancer is the commonest cause of gynaecological cancer deaths. First-line treatment for advanced disease includes a combination of platinum-taxane chemotherapy (post-operatively or peri-operatively) and maximal debulking surgery whenever feasible. Initial response rate to chemotherapy is high (up to 80%) but most patients will develop recurrence (approximately 70-90%) and succumb to the disease. Recently, poly-ADP-ribose polymerase (PARP) inhibition (by drugs such as Olaparib, Niraparib or Rucaparib) directed synthetic lethality approach in BRCA germline mutant or platinum sensitive disease has generated real hope for patients. PARP inhibitor (PARPi) maintenance therapy can prolong survival but therapeutic response is not sustained due to intrinsic or acquired secondary resistance to PARPi therapy. Reversion of BRCA1/2 mutation can lead to clinical PARPi resistance in BRCA-germline mutated ovarian cancer. However, in the more common platinum sensitive sporadic HGSOC, the clinical mechanisms of development of PARPi resistance remains to be defined. Here we provide a comprehensive review of the current status of PARPi and the mechanisms of resistance to therapy.