Comparison of Poly (ADP-ribose) Polymerase Inhibitors (PARPis) as Maintenance Therapy for Platinum-Sensitive Ovarian Cancer: Systematic Review and Network Meta-Analysis

Safety assessments and clinical features of PARP inhibitors from real-world data of Japanese patients with ovarian cancer

Poly (ADP-ribose) polymerase inhibitors have been increasingly used in ovarian cancer treatment. However, the real-world safety data of these drugs in Japanese patients are limited. This retrospective study included 181 patients with ovarian cancer who received olaparib or niraparib at two independent hospitals in Japan between May 2018 and December 2022. Clinical information and blood sampling data were collected. Regarding patient backgrounds, the olaparib group had higher proportions of patients with serous carcinoma, BRCA positivity, homologous recombination deficiency, and those receiving maintenance therapy after recurrence treatment than the niraparib group. Regarding toxicity properties, the most common reasons for discontinuation in the olaparib group were anemia, fatigue, and nausea, while the reason in the niraparib was thrombocytopenia. Thrombocytopenia caused by niraparib treatment occurred earlier than anemia caused by olaparib treatment. Patients with a low body mass index or who had undergone several previous treatment regimens were more likely to discontinue treatment within the first 3 months. Although we analyzed blood collection data, predicting treatment interruptions due to blood toxicity was challenging. In this study, we revealed the characteristics of patients and the timing of interruptions for each drug, highlighting the importance of carefully managing adverse effects.

Efficacy and safety of veliparib plus chemotherapy for the treatment of lung cancer: A systematic review of clinical trials

BACKGROUND

As a poly-ADP ribose polymerase (PARP) inhibitor, veliparib has been identified as a potential therapeutic agent for lung cancer. The present study aimed to conduct a systematic review of clinical trials investigating the efficacy and safety of veliparib for treating lung cancer.

METHODS

PubMed, Scopus, the Web of Science, and Google Scholar were systematically searched up to October 30, 2022. Only randomized controlled trials (RCTs) evaluating the efficacy or safety of veliparib in the treatment of lung cancer patients were included. Studies were excluded if they were not RCTs, enrolled healthy participants or patients with conditions other than lung cancer, or investigated therapeutic approaches other than veliparib. The Cochrane risk-of-bias tool was used for quality assessment.

RESULTS

The seven RCTs (n = 2188) showed that patients treated with a combination of veliparib and chemotherapy had a significantly higher risk of adverse events, when compared to the control arm. There was no statistically significant difference in overall survival (OS) between those treated with veliparib plus chemotherapy and those receiving the standard therapies. Only two trials demonstrated an improvement in progression-free survival (PFS), and only one study found an increase in objective response rate (ORR). Furthermore, adding veliparib to standard chemotherapy showed no benefit in extending the duration of response (DoR) in any of the studies.

CONCLUSIONS

Only a small number of studies have found veliparib to be effective, in terms of improved OS, PFS, and ORR, while the majority of studies found no benefit for veliparib over standard treatment.

Inhibiting PRMT5 induces DNA damage and increases anti-proliferative activity of Niraparib, a PARP inhibitor, in models of breast and ovarian cancer

BACKGROUND

Inhibitors of Poly (ADP-Ribose) Polymerases (PARP) provide clinical benefit to patients with breast and ovarian cancers, by compromising the DNA repair activity of cancer cells. Although these agents extend progression-free survival in many patients, responses can be short lived with many patients ultimately progressing. Identification of combination partners that increase dependence of cancer cells to the DNA repair activity of PARPs may represent a strategy to increase the utility of PARP inhibitors. Protein arginine methyltransferase 5 (PRMT5) regulates DNA damage response pathways through splicing and protein modification, and inhibitors of PRMT5 have recently entered clinical trials.

METHODS

The effect of PRMT5 inhibition on the levels of DNA damage and repair markers including γH2AX, RAD51, and 53BP1 was determined using high content immunofluorescent imaging. The anti-proliferative activity of the combination of PRMT5 and PARP inhibitors was evaluated using in vitro models of breast and ovarian cancers using both cell lines and ex vivo patient derived xenografts. Finally, the combinations of PRMT5 and PARP inhibitors were evaluated in cell line xenograft models in vivo.

RESULTS

Inhibition of PRMT5 by GSK3326595 led to increased levels of markers of DNA damage. The addition of GSK3326595 to the PARP inhibitor, niraparib, resulted in increased growth inhibition of breast and ovarian cancer cell lines and patient derived spheroids. In vivo, the combination improved the partial effects on tumor growth inhibition achieved by either single agent, producing complete tumor stasis and regression.

CONCLUSION

These data demonstrate that inhibition of PRMT5 induced signatures of DNA damage in models of breast and ovarian cancer. Furthermore, combination with the PARP inhibitor, Niraparib, resulted in increased anti-tumor activity in vitro and in vivo. Overall, these data suggest inhibition of PRMT5 as a mechanism to broaden and enhance the clinical application of PARP inhibitors.

Comprehensive Analysis of Adverse Events Induced by PARP Inhibitors Using JADER and Time to Onset

Poly (ADP-ribose) polymerase (PARP) inhibitors are effective against breast cancer susceptibility gene (BRCA) mutations. Clinical trials have reported hematologic toxicity and gastrointestinal symptoms as class effects of PARP inhibitors. However, information on adverse events (AEs) in a Japanese clinical cohort is currently lacking. In this study, we conducted a comprehensive survey of the AEs of two PARP inhibitors, olaparib and niraparib, using the Japanese Adverse Reaction Reporting (JADER) database provided by the Pharmaceuticals and Medical Devices Agency (PMDA). Moreover, we also analyzed the course and time to the onset of AEs. Signals were detected for 15 and 11 AEs for olaparib and niraparib, respectively. Most occurred within the first month of treatment with either agent. These results may indicate the importance of early response and monitoring after beginning PARP inhibitor therapy. The results of this study may be useful for managing side effects and suggesting supportive care for patients using PARP inhibitors in the future.

Comparative Efficacy and Safety of Poly (ADP-Ribose) Polymerase Inhibitors in Patients With Ovarian Cancer: A Systematic Review and Network Meta-Analysis

Objective

This study aims to compare the efficacy and safety of different poly (ADP-ribose) polymerase (PARP) inhibitors in patients with ovarian cancer through a network meta-analysis to support clinical treatment choices.

Methods

The Cochrane Library, PubMed, Embase, Science Citation Index, China National Knowledge Infrastructure (CNKI), Wanfang Data, Chongqing VIP (CQVIP), and Chinese BioMedical Literature Database (CBM) were searched with a cutoff date of 14 January 2021. ClinicalTrials.gov was also checked for supplementary data. Phase II or III randomized controlled trials that compared a PARP inhibitor with a placebo in patients with relapsed or newly diagnosed advanced ovarian cancer were included. The hazard ratios (HRs) for progression-free survival and overall survival and odds ratios (ORs) for grade 3 or higher adverse events were analyzed. The network meta-analysis was conducted in a Bayesian framework based on the Markov Chain Monte Carlo model in the R gemtc package (version 4.0.3).

Results

Eight eligible articles reporting six trials with a total of 2,801 patients were incorporated in this network meta-analysis. Three trials compared olaparib with placebo. Two trials compared niraparib with placebo. One trial compared rucaparib with placebo. The network meta-analysis failed to show significant differences in progression-free survival among the three PARP inhibitors: HR of 0.64, 95% confidence interval of 0.3 to 1.42 for olaparib versus niraparib, and olaparib versus rucaparib (0.86; 0.33 to 2.33). The comparison between niraparib and rucaparib also did not express a statistical difference (1.34; 0.47 to 3.72). Subgroup analysis bybreast cancer susceptibility gene (BRCA) status showed no obvious difference in progression-free survival among the three PARP inhibitors regardless of BRCA mutation status. Olaparib had fewer grade 3 or higher adverse events than niraparib (OR, 0.27; 95% confidence interval, 0.13 to 0.55) and rucaparib (0.34; 0.14 to 0.86). However, the analysis failed to show a significant difference between niraparib and rucaparib (1.27; 0.49 to 3.27).

Conclusion

Current evidence indicates that there is no significant difference observed in efficacy among olaparib, niraparib, and rucaparib. However, olaparib might have fewer grade 3 or higher adverse events.

European experts consensus: BRCA/homologous recombination deficiency testing in first-line ovarian cancer

BACKGROUND

Homologous recombination repair (HRR) enables fault-free repair of double-stranded DNA breaks. HRR deficiency is predicted to occur in around half of high-grade serous ovarian carcinomas. Ovarian cancers harbouring HRR deficiency typically exhibit sensitivity to poly-ADP ribose polymerase inhibitors (PARPi). Current guidelines recommend a range of approaches for genetic testing to identify predictors of sensitivity to PARPi in ovarian cancer and to identify genetic predisposition.

DESIGN

To establish a European-wide consensus for genetic testing (including the genetic care pathway), decision making and clinical management of patients with recently diagnosed advanced ovarian cancer, and the validity of biomarkers to predict the effectiveness of PARPi in the first-line setting. The collaborative European experts' consensus group consisted of a steering committee (n = 14) and contributors (n = 84). A (modified) Delphi process was used to establish consensus statements based on a systematic literature search, conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

RESULTS

A consensus was reached on 34 statements amongst 98 caregivers (including oncologists, pathologists, clinical geneticists, genetic researchers, and patient advocates). The statements concentrated on (i) the value of testing for BRCA1/2 mutations and HRR deficiency testing, including when and whom to test; (ii) the importance of developing new and better HRR deficiency tests; (iii) the importance of germline non-BRCA HRR and mismatch repair gene mutations for predicting familial risk, but not for predicting sensitivity to PARPi, in the first-line setting; (iv) who should be able to inform patients about genetic testing, and what training and education should these caregivers receive.

CONCLUSION

These consensus recommendations, from a multidisciplinary panel of experts from across Europe, provide clear guidance on the use of BRCA and HRR deficiency testing for recently diagnosed patients with advanced ovarian cancer.

Quantitative Analysis of the Efficacy of PARP Inhibitors as Maintenance Therapy in Recurrent Ovarian Cancer

Objective: This study aimed to establish a pharmacodynamic model and to screen reasonable covariates to quantitatively describe the efficacy of poly (ADP-ribose) polymerase inhibitors (PARPis) as maintenance treatment for recurrent ovarian cancer (ROC).

Methods: The log normal hazard function model was established by using progression-free survival (PFS) data of 1,169 patients from published randomized trials on FDA-approved PARP inhibitors (olaparib, niraparib, and rucaparib). Monte Carlo simulation was used to compare PFS values in different scenarios, such as monotherapy (administered alone) and combination therapy (PARPis combined with chemo- or target-therapies), different biomarker statuses, and different PARP inhibitors. PFS was also estimated.

Results: The study showed that the median PFS was 8.5 months with monotherapy and 16.0 months with combination therapy. The median PFS of patients with the BRCA mutation, BRCA wild-type, and HRD-positivity were 11.0, 7.5, and 9.0 months in monotherapy, respectively, and 23.0, 14.0 and 17.5 months, in combination therapy, respectively. In addition, the median PFS of olaparib, niraparib, and rucaparib monotherapy were about 9.5, 10.5, and 12.0 months, respectively, and about 19.0, 20.0, and 25 months, respectively, in combination therapy. The median PFS values in combination with cediranib, bevacizumab, and chemotherapy were approximately 17.0, 12.5 and 19.5 months, respectively.

Conclusion: PARPi combination therapy is more effective as maintenance treatment for ROC than monotherapy, and the efficacy of PARPis in combination with chemotherapy is higher than that of the combination with antiangiogenic drugs. We found that the PFS of BRCA wild-type was similar to that of HRD-positive patients, and there was no significant difference in PFS between olaparib, niraparib, and rucaparib, which provides necessary quantitative information for the clinical practice of PARPis in the treatment of ROC.

PARP Inhibitors and Haematological Malignancies-Friend or Foe?

Simple Summary

PARP inhibitors are a class of orally active drugs that kill a range of cancer types by inducing synthetic lethality. The usefulness of PARP inhibitors for the treatment of haematological malignancies has begun to be explored in a variety of both pre-clinical models and human clinical trials. Despite being largely considered safe and well tolerated, secondary haematological malignancies have arisen in patients following treatment with PARP inhibitors, raising concerns about their use. In this review, we discuss the potential benefits and risks for using PARP inhibitors as treatments for haematological malignancies.

Abstract

Since their introduction several years ago, poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have become the standard of care for breast and gynaecological cancers with BRCA gene mutations. Given that PARPi act by exploiting defective DNA repair mechanisms within tumour cells, they should be ideally suited to combatting haematological malignancies where these pathways are notoriously defective, even though BRCA mutations are rare. To date, despite promising results in vitro, few clinical trials in humans for haematological malignancies have been performed, and additional investigation is required. Paradoxically, secondary haematological malignancies have arisen in patients after treatment with PARPi, raising concerns about their potential use as therapies for any blood or bone marrow-related disorders. Here, we provide a comprehensive review of the biological, pre-clinical, and clinical evidence for and against treating individual haematological malignancies with approved and experimental PARPi. We conclude that the promise of effective treatment still exists, but remains limited by the lack of investigation into useful biomarkers unique to these malignancies.

Comparative safety and tolerability of approved PARP inhibitors in cancer: A systematic review and network meta-analysis

BACKGROUND

We aimed to evaluate comparative safety and tolerability of the approved PARP inhibitors in people with cancer.

METHODS

Eligible studies included randomized controlled trials comparing an approved PARP inhibitor (fluzoparib, olaparib, rucaparib, niraparib, or talazoparib) with placebo or chemotherapy in cancer patients. Outcomes of interest included: serious adverse event (SAE), discontinuation due to adverse event (AE), interruption of treatment due to AE, dose reduction due to AE, and specific grade 1-5 AEs.

RESULTS

Ten trials including 3763 participants and six treatments (olaparib, rucaparib, niraparib, talazoparib, placebo, and protocol-specified single agent chemotherapy) were identified. SAE and discontinuation of treatment did not differ significantly among the four approved PARP inhibitors. Regarding interruption of treatment and dose reduction due to AE, statistically significant differences and statistically non-significant trend were observed. Talazoparib is associated with a higher risk of interruption of treatment and dose reduction (excluding rucaparib) due to AE as compared with the other drugs. Niraparib showed a trend of lower risk of AE related dose reduction as compared with the other drugs. Furthermore, there were significant differences in specific grade 1-5 AE among the four drugs.

CONCLUSION

The safety profile of the four approved PARP inhibitors is comparable in terms of SAE and AE-related discontinuation of treatment. Statistically significant differences in the AEs spectrum and AEs related dose interruption and dose reduction demonstrated the prompt identification of AE and dose personalization seem mandatory to obtain maximal benefit from PARP inhibitors.

Differences in PARP Inhibitors for the Treatment of Ovarian Cancer: Mechanisms of Action, Pharmacology, Safety, and Efficacy

Poly(ADP-ribose) polymerases (PARP) are proteins responsible for DNA damage detection and signal transduction. PARP inhibitors (PARPi) are able to interact with the binding site for PARP cofactor (NAD+) and trapping PARP on the DNA. In this way, they inhibit single-strand DNA damage repair. These drugs have been approved in recent years for the treatment of ovarian cancer. Although they share some similarities, from the point of view of the chemical structure and pharmacodynamic, pharmacokinetic properties, these drugs also have some substantial differences. These differences may underlie the different safety profiles and activity of PARPi.