The m6A regulator KIAA1429 stabilizes RAB27B mRNA and promotes the progression of chronic myeloid leukemia and resistance to targeted therapy

Chronic myeloid leukemia (CML) is a common adult leukemia. Both the acute phase of the disease and the adverse effects of anti-cancer treatments can lead to a poor prognosis. The N6-methyladenine (m6A) modification plays an important regulatory role in various physiological and pathological processes. KIAA1429 is a known m6A regulator, but the biological role of KIAA1429 in CML is unclear. In this study, we observed that the m6A levels and KIAA1429 expression were significantly up-regulated in patients with blast phase CML. Notably, KIAA1429 regulated the total level of RNA m6A modification in the CML cells and promoted the malignant biological behaviors of CML cells, including proliferation, migration, and imatinib resistance. Inhibiting KIAA1429 in CML cells reduced the stability of RAB27B mRNA through the m6A/YTHDF1 axis, consequently inhibiting CML proliferation and drug efflux, ultimately increasing the sensitivity of CML cells to imatinib. Moreover, the knockdown of RAB27B also inhibited the proliferation and drug resistance of CML cells and promoted their apoptosis. Rucaparib, a recently developed anti-cancer agent, suppressed the expression of KIAA1429 and CML cell proliferation and promoted cell apoptosis. Rucaparib also inhibited the tumorigenesis of CML cells in vivo. The combined use of rucaparib and imatinib enhanced the sensitivity of CML cells to imatinib. Our study provides evidence that elevated KIAA1429 expression in the blast phase of CML enhances the stability of RAB27B mRNA through the m6A/YTHDF1 axis to up-regulate RAB27B expression, thereby promoting CML progression. Rucaparib exerts inhibitory effects on KIAA1429 expression and thus reduces CML progression.

PARP inhibitor era in ovarian cancer treatment: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Ovarian cancer is the eighth leading cause of cancer-related death among women, characterized by late diagnosis and a high relapse rate. In randomized controlled trials, we aimed to evaluate the efficacy and safety of PARP inhibitors (PARPi) in treating advanced ovarian cancer.

METHODS

This review was registered on PROSPERO (CRD42021283150), included all phase II and phase III randomized controlled trials (RCTs) assessing the effect of PARPi on ovarian cancer until the 13th of April, 2022. The main outcomes were progression- free survival (PFS), overall survival (OS), and adverse events (AEs). Pooled hazard ratios (HRs), and risk ratios (RRs) were calculated with 95% confidence intervals (95% CI). The random-effects model was applied in all analyses.

RESULTS

In the meta-analysis, 16 eligible RCTs were included, with a total of 5,815 patients. In recurrent ovarian cancer, PARPi maintenance therapy showed a significant PFS benefit over placebo in the total population (HR 0.34, CI 0.29-0.40), BRCA mutant (HR 0.24, CI 0.18-0.31), germline BRCA mutant (HR 0.23, CI 0.18-0.30), and BRCA wild-type cases (HR 0.50, CI 0.39-0.65). PARPi monotherapy also improved PFS (HR 0.62, CI 0.51-0.76) compared with chemotherapy in BRCAm patients with recurrent ovarian cancer. The use of PARPi maintenance therapy resulted in an improvement in PFS over placebo in newly-diagnosed cancers in the overall population (HR 0.46, CI 0.30-0.71) and the BRCAm population (HR 0.36, CI 0.29-0.44). Although the risk of severe AEs was increased by PARPi therapy compared to placebo in most settings investigated, these side effects were controllable with dose modification, and treatment discontinuation was required in the minority of cases.

CONCLUSIONS

PARPis are an effective therapeutic option for newly-diagnosed and recurrent ovarian cancer. Despite a minor increase in the frequency of serious adverse effects, they are generally well tolerated.

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

INTRODUCTION

Our systematic review and meta-analysis aimed to evaluate the clinical efficacy and safety of Rucaparib, a PARP inhibitor (PARPi), in patients with ovarian cancer and BRCA mutation.

METHODS

Online databases were comprehensively searched for all phase III Randomized trials that used Rucaparib therapy for ovarian cancer patients and patients having BRCA mutation. Efficacy results are progression-free survival and overall response rate in addition to addressing its safety concerns.

RESULTS

After pooling data from 4 clinical trials, the analysis showed a significant improvement in PFS among ovarian cancer patients and for the maintenance therapy with a hazard ratio (HR) of 0.49 (95% CI 0.34-0.73, p = 0.0003) and 0.42 (95% CI 0.29-0.62, p < 0.0001), respectively. For patients with BRCA mutations, the PFS showed significant improvement with a (HR) of 0.42 (95% CI 0.25-0.71, p < 0.001). A difference was observed in the risk of grade ≥ 3 TEAEs between the two groups (RR = 2.48; 95% CI 1.40-4.37).

CONCLUSION

Rucaparib demonstrated significant efficacy in improving PFS and ORR in ovarian cancer patients, particularly those having BRCA mutations. However, they should be closely monitored due to the greater risk of various adverse effects.

Personalized medicine for metastatic prostate cancer: The paradigm of PARP inhibitors

Despite remarkable progress in the last decade, metastatic prostate cancer (mPCa) remains incurable. The approval of PARP inhibitors (PARPis) represents a milestone in this field, which definitively enters the era of precision medicine, as mPCa is often enriched for defects of homologous recombination repair genes. PARPis are now used as single agents for patients with metastatic castration-resistant PCa. Moreover, combinations of PARPis plus androgen-receptor targeted agents and immune checkpoint inhibitors, and earlier applications of PARPis in the metastatic hormone-sensitive PCa are under evaluation, representing the possible upcoming applications of these agents. Mechanisms of sensitization and resistance have been only partially elucidated. In our review, we summarize the current clinical evidence regarding PARPis in mPCa and the future directions of these targeted agents.

Poly (ADP-Ribose) Polymerase Inhibitors in Patients With Urothelial Cancer

Poly ADP-ribose polymerase inhibitors (PARPis) have clinical activity in several cancers. The rationale of their therapeutic use in urothelial cancer (UC) resides in the high homologous-recombination repair (HRR) deficiency (HRD) prevalence and potential cross-sensitivity with platinum-based chemotherapy (PBCT). This review aims to summarize and analyze trials exploring the activity of PARPis in UC, focusing on patients who may benefit from those agents, the best clinical setting for the treatment and the benefit of the association with immune-checkpoint inhibitors (ICIs). We included all the available trials analyzing the activity of PARPis in UC in neoadjuvant, adjuvant, first or subsequent lines, and maintenance setting. We included PARPis in monotherapy and in association with other agents. The results in the maintenance setting are intriguing: ATLANTIS trial showed signals of improved progression-free survival in patients with known HRR aberrations, although the Meet-URO12 trial, with its negative results, suggested the failure of clinical selection based on platinum sensitivity only. Single-agent PARPis in pretreated patients showed discouraging results in an unselected population of chemo-refractory patients. Concerning the association of PARPis with ICIs, several trials are exploring their role in platinum-naïve setting; the results in the advanced setting were globally negative. Prior selection of HRD status is essential to identify patients who might benefit from PARPis. The ideal clinical settings seem to be the maintenance treatment and the combination with ICIs in platinum-naïve patients. Definitive results of ongoing and further trials will delineate the position for PARPis, if any, in UC therapy.

Poly (ADP-ribose) Polymerase Inhibitors Have Comparable Efficacy with Platinum Chemotherapy in Patients with BRCA-positive Metastatic Castration-resistant Prostate Cancer. A Systematic Review and Meta-analysis

CONTEXT

Testing for mutations in Breast Cancer Gene 1/2 (BRCA) has emerged as a novel decision-making tool for clinicians. Patients with metastatic castration-resistant prostate cancer (mCRPC) harboring pathogenic BRCA mutations can benefit from poly (ADP-ribose) polymerase inhibitor (PARPi) and platinum treatments, whereas the impact of the mutation on sensitivity to cabazitaxel and prostate-specific membrane antigen (PSMA)-ligand therapy is currently unknown.

OBJECTIVE

To assess the efficacy of PARPi, platinum, cabazitaxel, and PSMA-ligand therapies in BRCA-positive mCRPC.

EVIDENCE ACQUISITION

Databases were queried in February 2022. We performed data synthesis by using both proportional and individual patient data. For prostate-specific antigen (PSA) response rate (≥50% decrease from baseline [PSA50]) evaluation, we pooled event rates with 95% confidence intervals (CIs). Progression-free (PFS) and overall (OS) survival analyses with individual patient data were performed with the mixed-effect Cox proportional hazard model and single-arm random-effect analysis, providing pooled medians.

EVIDENCE SYNTHESIS

We included 23 eligible studies with 901 BRCA-positive mCRPC patients. PSA50 response rates for PARPi and platinum were 69% (CI: 53-82%), and 74% (CI: 49-90%), respectively. Analyses of OS data showed no difference between PARPi and platinum treatments (hazard ratio: 0.86; CI: 0.49-1.52; p = 0.6). The single-arm OS and PFS analyses revealed similarities among different PARPis; pooled PFS and OS medians were 9.7 mo (CI: 8.1-12.5) and 17.4 mo (CI: 12.7-20.1), respectively.

CONCLUSIONS

Our data revealed that different PARPis were similarly effective in terms of PFS and OS. Moreover, we found that PARPi and platinum therapy were comparable in terms of PSA50 response rate and OS, highlighting that platinum is a valid treatment option for BRCA-positive mCRPC patients. However, prospective interventional studies comparing these agents are essential to provide a higher level of evidence.

PATIENT SUMMARY

In this report, we found that different poly (ADP-ribose) polymerase inhibitors had similar efficacy, and platinum was a valid treatment option in BRCA-positive metastatic castration-resistant prostate cancer patients.

Efficacy and Safety of PARP Inhibitor Therapy in Advanced Ovarian Cancer: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

AIMS

This study aims to evaluate the efficacy and safety of PARP inhibitor therapy in advanced ovarian cancer and identify the optimal treatment for the survival of patients.

BACKGROUND

The diversity of PARP inhibitors makes clinicians confused about the optimal strategy and the most effective BRCAm mutation-based regimen for the survival of patients with advanced ovarian cancer.

OBJECTIVES

The objective of this study is to compare the effects of various PARP inhibitors alone or in combination with other agents in advanced ovarian cancer.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were searched for relevant studies on PARP inhibitors for ovarian cancer. Bayesian network meta-analysis was performed using Stata 15.0 and R 4.0.4. The primary outcome was the overall PFS, and the secondary outcomes included OS, AE3, DISAE, and TFST.

RESULTS

Fifteen studies involving 5,788 participants were included. The Bayesian network metaanalysis results showed that olaparibANDAI was the most beneficial in prolonging overall PFS and non-BRCAm PFS, followed by niraparibANDAI. However, for BRCAm patients, olaparibTR might be the most effective, followed by niraparibANDAI. Olaparib was the most effective for the OS of BRCAm patients. AI, olaparibANDAI, and veliparibTR were more likely to induce grade 3 or higher adverse events. AI and olaparibANDAI were more likely to cause DISAE.

CONCLUSION

PARP inhibitors are beneficial to the survival of patients with advanced ovarian cancer. The olaparibTR is the most effective for BRCAm patients, whereas olaparibANDAI and niraparibANDAI are preferable for non-BRCAm patients. Other: More high-quality studies are desired to investigate the efficacy and safety of PARP inhibitors in patients with other genetic performances.

A real-world disproportionality analysis of Rucaparib: Post-marketing Pharmacovigilance Data

BACKGROUND

Rucaparib has been approved for the maintenance treatment of adult patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer. However, the long-term safety of rucaparib in large sample population was unknown. The presented study aimed to evaluate rucaparib-associated adverse events (AEs) according to the real-world pharmacovigilance database.

METHODS

Disproportionality analysis was conducted to assess the association between rucaparib and its AEs. Data were collected from the international pharmacovigilance database of US FDA Adverse Event Reporting System (FAERS) between January 2017 and June 2022. The characteristics of rucaparib-related AEs, and the onset time were further analyzed.

RESULTS

A total of 9,296,694 AE reports were recorded in the FAERS during the study period, among which 7,087 reports were associated with rucaparib. About 135 rucaparib-related AE signals in 15 system organ class (SOCs) were identified. The most common AEs included anaemia, thrombocytopenia, nausea, vomiting, fatigue, blood creatinine increase, alanine aminotransferase increase, and aspartate aminotransferase increase, which were listed in the label for rucaparib. Of note, 21 new and unexpected significant AEs that off-label were also found in our study, such as preferred term (PTs) of intestinal obstruction, gastrooesophageal reflux disease, blood iron decreased, dehydration, and hypersomnia. The median onset time of rucaparib-related AEs was 12 days (interquartile range [IQR] 1-62 days), and had early failure types.

CONCLUSION

Our study demonstrated potential new AEs of rucaparib, and further studies were expected to confirm the results.

Patient-reported outcomes of maintenance rucaparib in patients with recurrent ovarian carcinoma in ARIEL3, a phase III, randomized, placebo-controlled trial

PURPOSE

To compare NFOSI-18 Disease Related Symptoms - Physical (DRSP), Total score, and side effect bother between maintenance rucaparib (600 mg twice daily) vs. placebo in the phase III ARIEL3 trial.

METHODS

ARIEL3 (NCT01968213) included patients with ovarian carcinoma who responded to second-line or later platinum-based chemotherapy. The NFOSI-18 DRS-P and Total scales were secondary endpoints. The NFOSI-18 contains a side effect impact item (GP5): "I am bothered by side effects of treatment." We compared treatment arms on change from baseline of DRS-P and Total scores using mixed models with repeated measures (MRMM). Time to first and confirmed deterioration of NFOSI-18 DRS-P and Total scales were analyzed using Cox regression. We also calculated the proportion of patients reporting moderate to high side effect bother on GP5.

RESULTS

In the intention-to-treat (ITT) cohort, mean change from baseline favored the placebo. Compared to placebo, rucaparib was associated with higher risk of deterioration [e.g., 4-point deteriorator definition hazard ratio (HR): 1.85; 95% CI: 1.46, 2.36; median time to first deterioration on DRSP: 1.9 vs. 7.0 months]. Confirmed deterioration results resembled those for first deterioration. Proportions of patients reporting moderate/high side effect bother on GP5 fluctuated around 20% across treatment cycles. Results in BRCA mutant and homologous recombination deficient cohorts were generally similar to those from the ITT cohort.

CONCLUSION

This placebo-controlled study in the maintenance therapy setting provides a unique view of the impact of PARP inhibition on the patient-reported outcomes that are commonly used in ovarian cancer clinical trials. Information regarding the adverse side effect impact of PARP inhibitors should be weighed against their clinical benefit.

Rucaparib for PARP inhibitor-pretreated ovarian cancer: A GEICO retrospective subgroup analysis from the Spanish Rucaparib Access Program

The poly(ADP-ribose) polymerase inhibitor (PARPi) rucaparib is approved as maintenance therapy for patients with platinum-sensitive recurrent high-grade ovarian cancer (HGOC). The efficacy and safety of rucaparib after PARPi therapy are largely unknown; therefore, we analyzed outcomes in the subgroup of PARPi-pretreated patients from Spanish hospitals participating in the Rucaparib Access Program. This post hoc subgroup analysis explored baseline characteristics, treatment exposure, safety, effectiveness, and subsequent therapy among women receiving rucaparib 600 mg twice daily after at least one prior PARPi for HGOC. Of 14 women eligible for the analysis, 11 (79%) had tumors harboring BRCA1/2 mutations. Patients had received a median of 5 (range 3-8) treatment lines before rucaparib. Twelve patients (86%) had previously received olaparib and two (14%) niraparib; 12 patients received rucaparib as treatment for platinum-resistant HGOC, one as treatment for platinum-sensitive HGOC, and one as maintenance therapy. Progression-free survival was 0.2-9.1 months. One of seven patients assessable for response by RECIST achieved stable disease. Adverse events occurred in 11 patients (79%; grade 3 in 29%), leading to treatment interruption in eight patients (57%), dose reduction in six (43%), but treatment discontinuation in only one (7%). No new safety signals were observed. This is one of the first reported series of real-world data on rucaparib after prior PARPi for HGOC. In this heavily pretreated population, rucaparib demonstrated meaningful activity in some patients and tolerability consistent with previous prospective trials. Future investigation should focus on identifying patients who may benefit from rucaparib after prior PARPi exposure.

Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization

The development of a lipid nano-delivery system was attempted for three specific poly (ADP-ribose) polymerase 1 (PARP1) inhibitors: Veliparib, Rucaparib, and Niraparib. Simple lipid and dual lipid formulations with 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1'-glycerol) sodium salt (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) were developed and tested following the thin-film method. DPPG-encapsulating inhibitors presented the best fit in terms of encapsulation efficiency (>40%, translates into concentrations as high as 100 µM), zeta potential values (below -30 mV), and population distribution (single population profile). The particle size of the main population of interest was ~130 nm in diameter. Kinetic release studies showed that DPPG-encapsulating PARP1 inhibitors present slower drug release rates than liposome control samples, and complex drug release mechanisms were identified. DPPG + Veliparib/Niraparib presented a combination of diffusion-controlled and non-Fickian diffusion, while anomalous and super case II transport was verified for DPPG + Rucaparib. Spectroscopic analysis revealed that PARP1 inhibitors interact with the DPPG lipid membrane, promoting membrane water displacement from hydration centers. A preferential membrane interaction with lipid carbonyl groups was observed through hydrogen bonding, where the inhibitors' protonated amine groups may be the major players in the PARP1 inhibitor encapsulation mode.

Novel breakthroughs in advanced prostate cancer management

INTRODUCTION

Although PSA screening has been rationalized, prostate cancer continues to have the highest incidence rate in 2021, and alone accounts for 26% of cancer diagnoses in men. A thorough review of the medical literature highlights a vast array of approved and investigational treatments for prostate cancer. Thus, selecting the best treatment option for the appropriate patient at the right time is crucial. Hence, biomarkers help in defining optimal patient stratification, revealing potential processes through which a drug might exert its impact and aid in the tailoring of treatments for efficient personalized medicine.

AREAS COVERED

This article is a pragmatic review of novel prostate cancer therapies that can help guide clinicians in tackling prostate cancer with the latest treatments.

EXPERT OPINION

Local radiotherapy has proven to be a game changer for low burden, de novo metastatic prostate cancer. Androgen deprivation therapy continues to be the ultimate treatment. Delaying resistance to these agents will undoubtedly be a breakthrough in the treatment of prostate cancer. When it comes to metastatic castrate resistant disease, treatment options become narrower. PARP inhibitors and N-terminal domain inhibitors, offer new hope, and have a synergistic effect with immunotherapy adding promising agents to the therapeutic arsenal.

Matching BRCA and prostate cancer in a public health system: Report of the Italian Society for Uro-Oncology (SIUrO) consensus project

The recent approval of PARP inhibitors for the treatment of metastatic -castration-resistant prostate cancer (mCRPC) patients with BRCA mutations firstly introduced the possibility of proposing a targeted treatment in this disease. However, the availability of this therapeutic option raises a number of questions concerning the management of prostate cancer in everyday clinical practice: the timing and method of detecting BRCA mutations, the therapeutic implications of the detection, and the screening of the members of the family of a prostate cancer patient with a BRCA alteration. These challenging issues led the Italian Society for Uro-Oncology (SIUrO) to organise a Consensus Conference aimed to develop suggestions capable of supporting clinicians managing prostate cancer patients. The present paper described the development of the statements discussed during the consensus, which involved all of the most important Italian scientific societies engaged in the multi-disciplinary and multi-professional management of the disease.

Rucaparib cocrystal: Improved solubility and bioavailability over camsylate

Rucaparib (Ruc) is a drug used to treat advanced ovarian cancer associated with deleterious BRCA mutations. Its commercial form, the camsylate salt (Ruc-Cam), suffers from poor aqueous solubility and thus causes low and erratic oral bioavailability. In this work, we aimed to improve the oral exposure of Ruc through cocrystallization. Liquid-assisted grinding, slurry, and solvent evaporation methods were employed to prepare new solid forms of Ruc. Cocrystals of rucaparib-theophylline monohydrate (Ruc-Thp MH), rucaparib-maltol (Ruc-Mal), and rucaparib-ethyl maltol (Ruc-Emal) were obtained. Powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption were utilized to characterize these multi-component systems. All cocrystals dissolve faster than Ruc-Cam at pH 2.0 and 4.5, and Ruc-Thp MH displays the highest apparent solubility in pH 4.5 and 6.8 buffers. Pharmacokinetic studies in rats show that Ruc-Thp MH exhibits 2.4 times the C_max and 1.4 times the AUC_0-24h at a single dose compared with Ruc-Cam. The enhanced solubility and bioavailability of Ruc-Thp MH showcase the power of cocrystallization in addressing absorption issues in drug development.

The PARP inhibitor Rucaparib synergizes with radiation to attenuate atypical teratoid rhabdoid tumor growth

Background

Atypical teratoid rhabdoid tumors (ATRT) are highly aggressive pediatric brain tumors. The available treatments rely on toxic chemotherapy and radiotherapy, which themselves can cause poor outcomes in young patients. Poly (ADP-ribose) polymerases (PARP), multifunctional enzymes which play an important role in DNA damage repair and genome stability have emerged as a new target in cancer therapy. An FDA-approved drug screen revealed that Rucaparib, a PARP inhibitor, is important for ATRT cell growth. This study aims to investigate the effect of Rucaparib treatment in ATRT.

Methods

This study utilized cell viability, colony formation, flow cytometry, western blot, immunofluorescence, and immunohistochemistry assays to investigate Rucaparib's effectiveness in BT16 and MAF737 ATRT cell lines. In vivo, intracranial orthotopic xenograft model of ATRT was used. BT16 cell line was transduced with a luciferase-expressing vector and injected into the cerebellum of athymic nude mice. Animals were treated with Rucaparib by oral gavaging and irradiated with 2 Gy of radiation for 3 consecutive days. Tumor growth was monitored using In Vivo Imaging System.

Results

Rucaparib treatment decreased ATRT cell growth, inhibited clonogenic potential of ATRT cells, induced cell cycle arrest and apoptosis, and led to DNA damage accumulation as shown by increased expression of γH2AX. In vivo, Rucaparib treatment decreased tumor growth, sensitized ATRT cells to radiation and significantly increased mice survival.

Conclusion

We demonstrated that Rucaparib has potential to be a new therapeutic strategy for ATRT as seen by its ability to decrease ATRT tumor growth both in vitro and in vivo.

Resistance to Poly (ADP-Ribose) Polymerase Inhibitors (PARPi): Mechanisms and Potential to Reverse

PURPOSE OF REVIEW

This review will focus on the most common mechanisms for poly (ADP-ribose) polymerase inhibitors' (PARPi) resistance and the main strategies for overcoming acquired or de novo PARPi resistance.

RECENT FINDINGS

Initial approvals for PARPi as part of treatment for advanced epithelial ovarian cancer (EOC) started in 2014 with patient with recurrent cancer characterized by BRCA mutations in the 3rd and 4th line and now have approvals for front-line maintenance in both the BRCA mutated and BRCAwt populations. As with all therapies, patients will eventually develop resistance to treatment. The most common mechanisms for PARPi resistance include reversion mutations, methylation events, and restoration of homologous recombination deficiency (HRD) through combinations and targeting replication stress. As more and more patients receive initial treatment (and potential retreatment with PARPi), we need to better understand the mechanisms in which tumors acquire PARPi resistance.

Clinical and molecular characteristics of ARIEL3 patients who derived exceptional benefit from rucaparib maintenance treatment for high-grade ovarian carcinoma

OBJECTIVE

ARIEL3 (NCT01968213) is a placebo-controlled randomized trial of the poly(ADP-ribose) polymerase inhibitor rucaparib as maintenance treatment in patients with recurrent high-grade ovarian carcinoma who responded to their latest line of platinum therapy. Rucaparib improved progression-free survival across all predefined subgroups. Here, we present an exploratory analysis of clinical and molecular characteristics associated with exceptional benefit from rucaparib.

METHODS

Patients were randomized 2:1 to receive rucaparib 600 mg twice daily or placebo. Molecular features (genomic alterations, BRCA1 promoter methylation) and baseline clinical characteristics were evaluated for association with exceptional benefit (progression-free survival ≥2 years) versus progression on first scan (short-term subgroup) and other efficacy outcomes.

RESULTS

Rucaparib treatment was significantly associated with exceptional benefit compared with placebo: 79/375 (21.1%) vs 4/189 (2.1%), respectively (p < 0.0001). Exceptional benefit was more frequent among patients with favorable baseline clinical characteristics and with carcinomas harboring molecular evidence of homologous recombination deficiency (HRD). A comparison between patients who derived exceptional benefit from rucaparib and those in the short-term subgroup revealed both clinical markers (no measurable disease at baseline, complete response to latest platinum, longer penultimate platinum-free interval) and molecular markers (BRCA1, BRCA2, RAD51C, and RAD51D alterations and genome-wide loss of heterozygosity) significantly associated with exceptional benefit.

CONCLUSIONS

Exceptional benefit in ARIEL3 was more common in, but not exclusive to, patients with favorable clinical characteristics or molecular features associated with HRD. Our results suggest that rucaparib can deliver exceptional benefit to a diverse set of patients with recurrent high-grade ovarian carcinoma.

Imaging PARP with [18F]rucaparib in pancreatic cancer models

PURPOSE

Rucaparib, an FDA-approved PARP inhibitor, is used as a single agent in maintenance therapy to provide promising treatment efficacy with an acceptable safety profile in various types of BRCA-mutated cancers. However, not all patients receive the same benefit from rucaparib-maintenance therapy. A predictive biomarker to help with patient selection for rucaparib treatment and predict clinical benefit is therefore warranted. With this aim, we developed [18F]rucaparib, an 18F-labelled isotopologue of rucaparib, and employed it as a PARP-targeting agent for cancer imaging with PET. Here, we report the in vitro and in vivo evaluation of [18F]rucaparib in human pancreatic cancer models.

METHOD

We incorporated the positron-emitting 18F isotope into rucaparib, enabling its use as a PET imaging agent. [18F]rucaparib binds to the DNA damage repair enzyme, PARP, allowing direct visualisation and measurement of PARP in cancerous models before and after PARP inhibition or other genotoxic cancer therapies, providing critical information for cancer diagnosis and therapy. Proof-of-concept evaluations were determined in pancreatic cancer models.

RESULTS

Uptake of [18F]rucaparib was found to be mainly dependent on PARP1 expression. Induction of DNA damage increased PARP expression, thereby increasing uptake of [18F]rucaparib. In vivo studies revealed relatively fast blood clearance of [18F]rucaparib in PSN1 tumour-bearing mice, with a tumour uptake of 5.5 ± 0.5%ID/g (1 h after i.v. administration). In vitro and in vivo studies showed significant reduction of [18F]rucaparib uptake by addition of different PARP inhibitors, indicating PARP-selective binding.

CONCLUSION

Taken together, we demonstrate the potential of [18F]rucaparib as a non-invasive PARP-targeting imaging agent for pancreatic cancers.

A phase II trial of bevacizumab and rucaparib in recurrent carcinoma of the cervix or endometrium

OBJECTIVE

The aim of this study was to examine the tolerability and efficacy of combination bevacizumab rucaparib therapy in patients with recurrent cervical or endometrial cancer.

PATIENTS & METHODS

Thirty-three patients with recurrent cervical or endometrial cancer were enrolled. Patients were required to have tumor progression after first line treatment for metastatic, or recurrent disease. Rucaparib was given at 600 mg BID twice daily for each 21-day cycle. Bevacizumab was given at 15 mg/kg on day 1 of each 21-day cycle. The primary endpoint was efficacy as determined by objective response rate or 6-month progression free survival.

RESULTS

Of the 33 patients enrolled, 28 were evaluable. Patients with endometrial cancer had a response rate of 17% while patients with cervical cancer had a response rate of 14%. Median progression free survival was 3.8 months (95% C·I 2.5 to 5.7 months), and median overall survival was 10.1 months (95% C·I 7.0 to 15.1 months). Patients with ARID1A mutations displayed a better response rate (33%) and 6-month progression free survival (PFS6) rate (67%) than the entire study population. Observed toxicity was similar to that of previous studies with bevacizumab and rucaparib.

CONCLUSIONS

The combination of bevacizumab with rucaparib did not show significantly increased anti-tumor activity in all patients with recurrent cervical or endometrial cancer. However, patients with ARID1A mutations had a higher response rate and PFS6 suggesting this subgroup may benefit from the combination of bevacizumab and rucaparib. Further study is needed to confirm this observation. No new safety signals were seen.

Appropriate Selection of PARP Inhibitors in Ovarian Cancer

OPINION STATEMENT

Poly-ADP-ribose polymerase inhibitors (PARPi) are a class of anti-cancer drugs that target DNA repair pathways and have shown promising efficacy in patients with ovarian cancer in recent clinical trials. To date, there have been 9 FDA PARPi approvals/indications in ovarian cancer since 2014, highlighting the importance of this class of agents in the treatment of ovarian cancer. BRCA1/2-mutated tumors or other forms of homologous recombination deficient (HRD) tumors are particularly susceptible to PARP inhibition and have seen the greatest benefits of improvement in response rate and progression-free survival (PFS) in clinical trials. Patients with homologous recombination-proficient tumors also receive benefit, especially when a nice response to paltinum is noted, but to a lesser extent. PARP inhibitors now have FDA approval and indications in first-line and recurrent maintenance, and treatment. PARP inhibitor use as maintenance therapy in the front-line setting is now considered the standard of care in patients with BRCA1/2 mutations based on the SOLO-1/GOG-3004/ENGOT study. PARP inhibitors are also recommended per ASCO guidelines in all patients with ovarian cancer as front-line maintenance therapy based on the PRIMA/ENGOT-OV26/GOG-3012 trial. The combination of PARP inhibitor, olaparib, and the anti-angiogenesis inhibitor bevacizumab is also approved as maintenance therapy after front-line chemotherapy treatment in patients with HRD tumors and is an option for patients who have initiated bevacizumab with their chemotherapy treatment. PARPi are also FDA approved and can be utilized as a treatment in third-line and beyond in recurrent ovarian cancer patients with BRCA1/2 mutations and HRD tumors. In this review, we will cover in detail when PARP inhibitor use is appropriate in ovarian cancer, as well as the various clinical factors to take into consideration when selecting a PARP inhibitor regimen.

Design and synthesis of benzodiazepines as brain penetrating PARP-1 inhibitors

The poly (ADP-ribose) polymerase (PARP) inhibitors play a crucial role in cancer therapy. However, most approved PARP inhibitors cannot cross the blood-brain barrier, thus limiting their application in the central nervous system. Here, 55 benzodiazepines were designed and synthesised to screen brain penetrating PARP-1 inhibitors. All target compounds were evaluated for their PARP-1 inhibition activity, and compounds with better activity were selected for further assays in vitro. Among them, compounds H34, H42, H48, and H52 displayed acceptable inhibition effects on breast cancer cells. Also, computational prediction together with the permeability assays in vitro and in vivo proved that the benzodiazepine PARP-1 inhibitors we synthesised were brain permeable. Compound H52 exhibited a B/P ratio of 40 times higher than that of Rucaparib and would be selected to develop its potential use in neurodegenerative diseases. Our study provided potential lead compounds and design strategies for the development of brain penetrating PARP-1 inhibitors.

HIGHLIGHTS

Structural fusion was used to screen brain penetrating PARP-1 inhibitors.

55 benzodiazepines were evaluated for their PARP-1 inhibition activity.

Four compounds displayed acceptable inhibition effects on breast cancer cells.

The benzodiazepine PARP-1 inhibitors were proved to be brain permeable.

Characterization of patients with long-term responses to rucaparib treatment in recurrent ovarian cancer

OBJECTIVE

To describe molecular and clinical characteristics of patients with high-grade recurrent ovarian carcinoma (HGOC) who had long-term responses to the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib.

METHODS

This post hoc analysis pooled patients from Study 10 (NCT01482715; Parts 2A and 2B; n = 54) and ARIEL2 (NCT01891344; Parts 1 and 2; n = 491). Patients with investigator-assessed complete or partial response per RECIST were classified based on duration of response (DOR): long (≥1 year), intermediate (6 months to <1 year), or short (<6 months). Next-generation sequencing was used to detect deleterious mutations and loss of heterozygosity (LOH) in tumors.

RESULTS

Overall, 25.3% (138/545) of enrolled patients were responders. Of these, 27.5% (38/138) had long-term responses; 28.3% (39/138) were intermediate- and 34.8% (48/138) were short-term responders. Most of the long-term responders harbored a BRCA1 or BRCA2 (BRCA) mutation (71.1%, 27/38), and BRCA structural variants were most frequent among long-term responders (14.8%; 4/27). Responders with HGOC harboring a BRCA structural variant (n = 5) had significantly longer DOR than patients with other mutation types (n = 81; median not reached vs 0.62 years; HR, 0.21; 95% CI, 0.10-0.43; unadjusted p = 0.014). Among responders with BRCA wild-type HGOC, most long- and intermediate-term responders had high genome-wide LOH: 81.8% (9/11) and 76.9% (10/13), respectively, including 7 with deleterious RAD51C, RAD51D, or CDK12 mutations.

CONCLUSION

Among patients who responded to rucaparib, a substantial proportion achieved responses lasting ≥1 year. These analyses demonstrate the relationship between DOR to PARP inhibitor treatment and molecular characteristics in HGOC, such as presence of reversion-resistant BRCA structural variants.

Precision Oncology with Drugs Targeting the Replication Stress, ATR, and Schlafen 11

Precision medicine aims to implement strategies based on the molecular features of tumors and optimized drug delivery to improve cancer diagnosis and treatment. DNA replication is a logical approach because it can be targeted by a broad range of anticancer drugs that are both clinically approved and in development. These drugs increase deleterious replication stress (RepStress); however, how to selectively target and identify the tumors with specific molecular characteristics are unmet clinical needs. Here, we provide background information on the molecular processes of DNA replication and its checkpoints, and discuss how to target replication, checkpoint, and repair pathways with ATR inhibitors and exploit Schlafen 11 (SLFN11) as a predictive biomarker.

A phase 1, open-label, drug-drug interaction study of rucaparib with rosuvastatin and oral contraceptives in patients with advanced solid tumors

Purpose

This study aimed at evaluating the effect of rucaparib on the pharmacokinetics of rosuvastatin and oral contraceptives in patients with advanced solid tumors and the safety of rucaparib with and without coadministration of rosuvastatin or oral contraceptives.

Methods

Patients received single doses of oral rosuvastatin 20 mg (Arm A) or oral contraceptives ethinylestradiol 30 µg + levonorgestrel 150 µg (Arm B) on days 1 and 19 and continuous doses of rucaparib 600 mg BID from day 5 to 23. Serial blood samples were collected with and without rucaparib for pharmacokinetic analysis.

Results

Thirty-six patients (n = 18 each arm) were enrolled and received at least 1 dose of study drug. In the drug–drug interaction analysis (n = 15 each arm), the geometric mean ratio (GMR) of maximum concentration (C_max) with and without rucaparib was 1.29 for rosuvastatin, 1.09 for ethinylestradiol, and 1.19 for levonorgestrel. GMR of area under the concentration–time curve from time zero to last quantifiable measurement (AUC_0–last) was 1.34 for rosuvastatin, 1.43 for ethinylestradiol, and 1.56 for levonorgestrel. There was no increase in frequency of treatment-emergent adverse events (TEAEs) when rucaparib was given with either of the probe drugs. In both arms, most TEAEs were mild in severity and considered unrelated to study treatment.

Conclusion

Rucaparib 600 mg BID weakly increased the plasma exposure to rosuvastatin or oral contraceptives. Rucaparib safety profile when coadministered with rosuvastatin or oral contraceptives was consistent with that of rucaparib monotherapy. Dose adjustments of rosuvastatin and oral contraceptives are not necessary when coadministered with rucaparib.

ClinicalTrials.gov NCT03954366; Date of registration May 17, 2019.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-021-04338-7.

Pharmacokinetics and safety of rucaparib in patients with advanced solid tumors and hepatic impairment

PURPOSE

The poly(ADP-ribose) polymerase inhibitor rucaparib is approved for the treatment of patients with recurrent ovarian and metastatic castration-resistant prostate cancer; however, limited data are available on its use in patients with hepatic dysfunction. This study investigated whether hepatic impairment affects the pharmacokinetics, safety, and tolerability of rucaparib in patients with advanced solid tumors.

METHODS

Patients with normal hepatic function or moderate hepatic impairment according to the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria were enrolled and received a single oral dose of rucaparib 600 mg. Concentrations of rucaparib and its metabolite M324 in plasma and urine were measured. Pharmacokinetic parameters were compared between hepatic function groups, and safety and tolerability were assessed.

RESULTS

Sixteen patients were enrolled (n = 8 per group). Rucaparib maximum concentration (Cmax) was similar, while the area under the concentration-time curve from time 0 to infinity (AUC0-inf) was mildly higher in the moderate hepatic impairment group than in the normal control group (geometric mean ratio, 1.446 [90% CI 0.668-3.131]); similar trends were observed for M324. Eight (50%) patients experienced ≥ 1 treatment-emergent adverse event (TEAE); 2 had normal hepatic function and 6 had moderate hepatic impairment.

CONCLUSION

Patients with moderate hepatic impairment showed mildly increased AUC0-inf for rucaparib compared to patients with normal hepatic function. Although more patients with moderate hepatic impairment experienced TEAEs, only 2 TEAEs were considered treatment related. These results suggest no starting dose adjustment is necessary for patients with moderate hepatic impairment; however, close safety monitoring is warranted.

Rationale for combination PARP inhibitor and antiangiogenic treatment in advanced epithelial ovarian cancer: A review

Inhibitors of poly(ADP-ribose) polymerase (PARP) and angiogenesis have demonstrated single-agent activity in women with advanced ovarian cancer. Recent studies have aimed to establish whether combination therapy can augment the response seen with PARP inhibitors or antiangiogenic agents alone. This review provides an overview of PARP inhibitors and antiangiogenics as monotherapy in women with advanced ovarian cancer, explores potential mechanisms of action of PARP inhibitor and antiangiogenic combination treatments, reviews efficacy and safety data from trials evaluating this combination, and outlines ongoing and future trials evaluating this combination, discussing these in the context of the current and future treatment landscape for women with advanced ovarian cancer. Sentinel studies evaluating PARP inhibitor (n = 8), antiangiogenic (n = 4), and combination (n = 7) therapy were identified in women with newly diagnosed (n = 7) and recurrent (n = 12) ovarian cancer. PARP inhibitors included olaparib (n = 9), niraparib (n = 4), rucaparib (n = 1), and veliparib (n = 1). Antiangiogenic agents included bevacizumab (n = 7) and cediranib (n = 4). PARP inhibitors combined with antiangiogenics demonstrated efficacy based on objective response rates and progression-free survival (PFS) in the relapsed disease setting. Maintenance therapy with the PARP inhibitor, olaparib, plus antiangiogenic therapy offered a significant PFS benefit versus the antiangiogenic alone in women with newly diagnosed advanced ovarian cancer who tested positive for homologous recombination deficiency. Combination therapy was tolerated, with no new safety signals reported compared with monotherapy trials. PARP inhibitors and antiangiogenics have changed the landscape of ovarian cancer treatment. The PARP inhibitor plus antiangiogenic combination is a novel treatment option that appears promising in the first-line advanced and recurrent ovarian cancer settings, although the role of this combination in recurrent disease requires further elucidation. Defining which patients are candidates for monotherapy or combination therapy is critical, taking into consideration safety profiles of therapies alone or in combination, and how these treatments should be sequenced in clinical practice.

Population exposure-efficacy and exposure-safety analyses for rucaparib in patients with recurrent ovarian carcinoma from Study 10 and ARIEL2

OBJECTIVE

To evaluate correlations between rucaparib exposure and selected efficacy and safety endpoints in patients with recurrent ovarian carcinoma using pooled data from Study 10 and ARIEL2.

METHODS

Efficacy analyses were limited to patients with carcinomas harboring a deleterious BRCA1 or BRCA2 mutation who had received ≥2 prior lines of chemotherapy. Safety was evaluated in all patients who received ≥1 rucaparib dose. Steady-state daily area under the concentration-time curve (AUCss) and maximum concentration (Cmax,ss) for rucaparib were calculated for each patient and averaged by actual dose received over time (AUCavg,ss and Cmax,avg,ss) using a previously developed population pharmacokinetic model.

RESULTS

Rucaparib exposure was dose-proportional and not associated with baseline patient weight. In the exposure-efficacy analyses (n = 121), AUCavg,ss was positively associated with independent radiology review-assessed RECIST response in the subgroup of patients with platinum-sensitive recurrent disease (n = 75, p = 0.017). In the exposure-safety analyses (n = 393, 40 mg once daily to 840 mg twice daily [BID] starting doses), most patients received a 600 mg BID rucaparib starting dose, with 27% and 21% receiving 1 or ≥2 dose reductions, respectively. Cmax,ss was significantly correlated with grade ≥2 serum creatinine increase, grade ≥3 alanine transaminase/aspartate transaminase increase, platelet decrease, fatigue/asthenia, and maximal hemoglobin decrease (p < 0.05).

CONCLUSION

The exposure-response analyses provide support for the approved starting dose of rucaparib 600 mg BID for maximum clinical benefit with subsequent dose modification only following the occurrence of a treatment-emergent adverse event in patients with BRCA-mutated recurrent ovarian carcinoma.

Efficacy and safety of rucaparib in previously treated, locally advanced or metastatic urothelial carcinoma from a phase 2, open-label trial (ATLAS)

BACKGROUND

ATLAS evaluated the efficacy and safety of the PARP inhibitor rucaparib in patients with previously treated locally advanced/unresectable or metastatic urothelial carcinoma (UC).

METHODS

Patients with UC were enrolled independent of tumor homologous recombination deficiency (HRD) status and received rucaparib 600 mg BID. The primary endpoint was investigator-assessed objective response rate (RECIST v1.1) in the intent-to-treat and HRD-positive (loss of genome-wide heterozygosity ≥10%) populations. Key secondary endpoints were progression-free survival (PFS) and safety. Disease control rate (DCR) was defined post-hoc as the proportion of patients with a confirmed complete or partial response (PR), or stable disease lasting ≥16 weeks.

RESULTS

Of 97 enrolled patients, 20 (20.6%) were HRD-positive, 30 (30.9%) HRD-negative, and 47 (48.5%) HRD-indeterminate. Among 95 evaluable patients, there were no confirmed responses. However, reductions in the sum of target lesions were observed, including 6 (6.3%) patients with unconfirmed PR. DCR was 11.6%; median PFS was 1.8 months (95% CI, 1.6-1.9). No relationship was observed between HRD status and efficacy endpoints. Median treatment duration was 1.8 months (range, 0.1-10.1). Most frequent any-grade treatment-emergent adverse events were asthenia/fatigue (57.7%), nausea (42.3%), and anemia (36.1%). Of 64 patients with data from tumor tissue samples, 10 (15.6%) had a deleterious alteration in a DNA damage repair pathway gene, including four with a deleterious BRCA1 or BRCA2 alteration.

CONCLUSIONS

Rucaparib did not show significant activity in unselected patients with advanced UC regardless of HRD status. The safety profile was consistent with that observed in patients with ovarian or prostate cancer.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov (NCT03397394). Date of registration: 12 January 2018. This trial was registered in EudraCT (2017-004166-10).

Poly (ADP-ribose) polymerase inhibitors in solid tumours: Systematic review and meta-analysis

BACKGROUND

Poly (ADP-ribose) polymerase-inhibitors (PARPis) showed antitumour activity in BRCA1/2-mutated cancers, with more heterogeneous outcomes in tumours harbouring mutations that impair other genes involved in the DNA homologous recombination repair (HRR) or wild-type (wt).

METHODS

We conducted a systematic review and meta-analysis to better assess the role of PARPis in the treatment of metastatic solid tumours, with and without BRCA1/2 mutations. The primary end-point was progression-free survival (PFS). The secondary end-points were overall response rate (ORR) and overall survival (OS). A random-effects model was applied.

RESULTS

Twenty-nine studies (8,839 patients) were included. PFS was significantly improved (hazard ratio [HR]: 0.59, 95% confidence interval [CI]: 0.51-0.68, p < 0.001), without being affected by BRCA mutational status (p = 0.65). Significant subgroup differences were observed with regard to the tumour site (p = 0.001), line of therapy (p = 0.002), control arm (p < 0.001), type of PARPi (p < 0.001) and trials' phase (p = 0.006). PARPis were associated with ORR (relative risk: 1.35, 95% CI: 1.16-1.56, p < 0.001), with significant subgroup differences observed with regard to treatment line (p = 0.03), control arm (p = 0.04) and PARPis (p < 0.001) and independent of mutational status (p = 0.44), tumour site (p = 0.86) and trials' phase (p = 0.09). OS was significantly improved by PARPis (HR: 0.86, 95% CI: 0.80-0.92, p < 0.001), regardless of mutational status (p = 0.57), tumour site (p = 0.82), treatment line (p = 0.22), control arm (p = 0.21), PARPis (p = 0.30) and trials' phase (p = 0.26). Finally, an exploratory subgroup analysis showed a significant PFS improvement (HR: 0.51, 95% CI: 0.43-0.60, p < 0.001) with PARPis in BRCA-wt/HRR-deficient tumours.

CONCLUSION

Our results confirm the efficacy of already approved PARPi-based treatments in BRCA1/2-mutant solid tumours, support their role also in BRCA-independent HRR-deficient tumours and suggest a potentially broader efficacy in some wt tumours, perhaps with appropriate therapeutic partners. Prospective studies are warranted.

PARP Inhibitors and Prostate Cancer: To Infinity and Beyond BRCA

The U.S. Food and Drug Administration recently approved two poly-adenosine diphosphate-ribose polymerase (PARP) inhibitors, olaparib and rucaparib, for treatment of biomarker-positive metastatic castrate resistant prostate cancer. The benefits of PARP inhibition have been well characterized in patients who have BRCA1 and BRCA2 mutations in several forms of cancer. BRCA1 and BRCA2 occupy key roles in DNA damage repair, which is comprised of several different pathways with numerous participants. Patients with mutations in other key genes within the DNA damage repair pathway may also respond to treatment with PARP inhibitors, and identification of these alterations could significantly increase the percentage of patients that may benefit from PARP inhibition. This review focuses on the potential for synthetically lethal interactions between PARP inhibitors and non-BRCA DNA damage repair genes. IMPLICATIONS FOR PRACTICE: The treatment potential of PARP inhibition has been well characterized in patients with BRCA1 and BRCA2 mutations, but there is compelling evidence for expanding the use of PARP inhibitors to mutations of other non-BRCA DNA damage repair (DDR) genes. This could increase the percentage of patients that may benefit from treatment with PARP inhibitors alone or in combination with other therapies. Understanding the significance of PARP inhibitor-sensitizing alterations in other common non-BRCA DDR genes will help guide clinical decisions to provide targeted treatment options to a wider population of patients.

FDA Approval Summary: Rucaparib for the Treatment of Patients with Deleterious BRCA-Mutated Metastatic Castrate-Resistant Prostate Cancer

The U.S. Food and Drug Administration (FDA) granted accelerated approval to rucaparib in May 2020 for the treatment of adult patients with deleterious BRCA mutation (germline and/or somatic)-associated metastatic castrate-resistant prostate cancer (mCRPC) who have been treated with androgen receptor-directed therapy and a taxane. This approval was based on data from the ongoing multicenter, open-label single-arm trial TRITON2. The primary endpoint, confirmed objective response rate, in the 62 patients who met the above criteria, was 44% (95% confidence interval [CI]: 31%-57%). The median duration of response was not estimable (95% CI: 6.4 to not estimable). Fifty-six percent of patients had a response duration of >6 months and 15% >12 months. The safety profile of rucaparib was generally consistent with that of the class of poly-(ADP-ribose) polymerase enzyme inhibitors and other trials of rucaparib in the treatment of ovarian cancer. Deaths due to adverse events (AEs) occurred in 1.7% of patients, and 8% discontinued rucaparib because of an AE. Grade 3-4 AEs occurred in 59% of patients. No patients with prostate cancer developed myelodysplastic syndrome or acute myeloid leukemia. The trial TRITON3 in patients with mCRPC is ongoing and is planned to verify the clinical benefit of rucaparib in mCRPC. This article summarizes the FDA thought process and data supporting this accelerated approval. IMPLICATIONS FOR PRACTICE: The accelerated approval of rucaparib for the treatment of adult patients with deleterious BRCA mutation (germline and/or somatic)-associated metastatic castrate-resistant prostate cancer who have been treated with androgen receptor-directed therapy and a taxane represents the first approved therapy for this selected patient population. This approval was based on a single-arm trial demonstrating a confirmed objective response rate greater than that of available therapy with a favorable duration of response and an acceptable toxicity profile. The ongoing trial TRITON3 is verifying the clinical benefit of this drug.

BET, SRC, and BCL2 family inhibitors are synergistic drug combinations with PARP inhibitors in ovarian cancer

BACKGROUND

Homologous recombination deficiencies (HRD) are present in approximately half of epithelial ovarian cancers, for which PARP inhibitors (PARPi) are becoming a preferred treatment option. However, a considerable proportion of these carcinomas acquire resistance or harbour de novo resistance, posing a significant challenge to treatment.

METHODS

To identify new combinatorial therapeutics to overcome resistance to PARPi, we employed high-throughput conditional RNAi and drug screening of patient-derived ovarian cancer cells. To prioritise clinically relevant drug combinations, we integrated empirical validation with analysis of The Cancer Genome Atlas (TCGA) and Genomics of Drug Sensitivity in Cancer (GDSC) datasets to nominate candidate targets and drugs, reaching three main findings.

FINDINGS

Firstly, we found that the PARPi rucaparib enhanced the effect of BET inhibitors (CPI-203 & CPI-0610) irrespective of clinical subtype or HRD status. Additional drug combination screens identified that dasatinib, a non-receptor tyrosine kinase inhibitor, augmented the effects of rucaparib and BET inhibitors, proposing a potential broadly applicable triple-drug combination for high-grade serous and clear cell ovarian carcinomas. Secondly, rucaparib synergised with the BCL2 family inhibitor navitoclax, with preferential activity in ovarian carcinomas that harbour alterations in BRCA1/2, BARD1, or MSH2/6. Thirdly, we identified potentially antagonistic drug combinations between the PARPi rucaparib and vinca alkaloids, anthracyclines, and antimetabolites, cautioning their use in the clinic.

INTERPRETATION

These findings propose therapeutic strategies to address PARP inhibitor resistance using agents that are already approved or are in clinical development, with the potential for rapid translation to benefit a broad population of ovarian cancer patients.

The effect of age on efficacy, safety and patient-centered outcomes with rucaparib: A post hoc exploratory analysis of ARIEL3, a phase 3, randomized, maintenance study in patients with recurrent ovarian carcinoma

BACKGROUND

In the phase 3 trial ARIEL3, maintenance treatment with the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib provided clinical benefit versus placebo for patients with recurrent, platinum-sensitive ovarian cancer. Here, we evaluate the impact of age on the clinical utility of rucaparib in ARIEL3.

METHODS

Patients with platinum-sensitive, recurrent ovarian carcinoma with ≥2 prior platinum-based chemotherapies who responded to their last platinum-based therapy were enrolled in ARIEL3 and randomized 2:1 to rucaparib 600 mg twice daily or placebo. Exploratory, post hoc analyses of progression-free survival (PFS), patient-centered outcomes (quality-adjusted PFS [QA-PFS] and quality-adjusted time without symptoms or toxicity [Q-TWiST]), and safety were conducted in three age subgroups (<65 years, 65-74 years, and ≥75 years).

RESULTS

Investigator-assessed PFS was significantly longer with rucaparib than placebo in patients aged <65 years (rucaparib n = 237 vs placebo n = 117; median, 11.1 vs 5.4 months; hazard ratio [HR]: 0.33 [95% confidence interval (95% CI) 0.25-0.43]; P < 0.0001) and 65-74 years (n = 113 vs n = 64; median, 8.3 vs 5.3 months; HR 0.43 [95% CI 0.29-0.63]; P < 0.0001) and numerically longer in patients aged ≥75 years (n = 25 vs n = 8; median, 9.2 vs 5.5 months; HR 0.47 [95% CI 0.16-1.35]; P = 0.1593). QA-PFS and Q-TWiST were significantly longer with rucaparib than placebo across all age subgroups. Safety of rucaparib was generally similar across the age subgroups.

CONCLUSIONS

Efficacy, patient-centered outcomes, and safety of rucaparib were similar between age subgroups, indicating that all eligible women with recurrent ovarian cancer should be offered this therapeutic option, irrespective of age. https://clinicaltrials.gov/ct2/show/NCT01968213.

When and How to Use PARP Inhibitors in Prostate Cancer: A Systematic Review of the Literature with an Update on On-Going Trials

CONTEXT

The goal of precision oncology is to use the underlying genomic characteristics of the patient and the cancer to select the optimal treatment at a given time. The recent Food and Drug Administration (FDA) approval of the poly(ADP-ribose) polymerase (PARP) inhibitors olaparib and rucaparib for the treatment of advanced prostate cancer heralds the onset of precision medicine for this disease.

OBJECTIVE

To discuss the emerging role that PARP inhibitors may play as a personalised future treatment option in patients with prostate cancer, with a focus on patients with metastatic castration-resistant prostate cancer (mCRPC) whose tumour cells harbour mutations resulting from deficient homologous recombination repair (HRR).

EVIDENCE ACQUISITION

To identify publications relevant to this review, a systematic literature search of PubMed was conducted for articles and proceedings of relevant major congresses, published between January 2010 and March 2020, reporting the use of PARP inhibitors in the treatment of cancers.

EVIDENCE SYNTHESIS

A total of 168 publications were identified, and 18 of these met the criteria for subsequent review. In addition, 15 phase 2 or on-going phase 3 (mCRPC) studies evaluating PARP inhibitors as monotherapy or in combination, which had not yet reported data, were identified through ClinicalTrials.gov. Emerging data suggest that the greatest efficacy with single-agent PARP inhibitors is seen in mCRPC patients with germline or somatic BRCA1/2 alterations (especially BRCA2 or biallelic mutations), with potential efficacy also observed in men with PALB2 and FANCA mutations.

CONCLUSIONS

PARP inhibitors have demonstrated efficacy in mCRPC, and similar to ovarian and breast cancers, the greatest effect is observed in patients with HRR deficiency. The PARP inhibitors olaparib and rucaparib are now FDA approved for mCRPC patients with HRR mutations and BRCA1/2 mutations, respectively. Furthermore, when PARP inhibition is combined with novel hormonal therapies, a treatment benefit may be observed regardless of the HRR deficiency status. Gaps in the knowledge and understanding around PARP inhibitor use in prostate cancer, including the most appropriate diagnostic testing method for identifying an HRR mutation, remain to be resolved.

PATIENT SUMMARY

The poly(ADP-ribose) polymerase (PARP) inhibitors olaparib and rucaparib are now approved by the Food and Drug Administration for the treatment of advanced prostate cancer. Here, we reviewed the literature and proceedings from meeting presentations and published papers relevant to the use of PARP inhibitors in the treatment of prostate cancer. Testing methods for detecting homologous recombination repair gene mutations, as diagnostic tools to help identify patients most likely to benefit from PARP inhibitor treatment, are also discussed.

Incorporating Parp-inhibitors in Primary and Recurrent Ovarian Cancer: A Meta-analysis of 12 phase II/III randomized controlled trials

BACKGROUND

The second decade of 2000s is witnessing a new ovarian cancer (OC) paradigm shift thanks to the results recently obtained by a new class of targeted agents: the Poly(ADP-ribose)polymerase (PARP)-Inhibitors (PARPi). Aim of this meta-analysis is to analyze available results obtained with PARPi, administered alone or in combination with chemo- and/or target-therapies in terms of efficacy and safety for the treatment of recurrent and primary advanced OC.

METHODS

On December 2019, all published phase II/III randomized clinical studies were systematically searched using the terms "[Parp-Inhibitor] AND [ovar*]". Twelve phase II/III randomized controlled trials were identified, with a total number of 5171 patients included.

RESULTS

Results demonstrated that PARPi account for a significant improvement of PFS in both recurrent and primary OC setting, independently from their administration schedule and independently from patients' BRCA mutational status. Moreover, patients harboring a Homologous Recombination Deficiency (HRD) positive testing primary or recurrent OC progress significantly later after PARPi administration/association. Results also reported that PARPi increase the occurrence of severe (G3-G4) anemia. Furthermore, severe fatigue occurred more frequently among patients subjected to PARPi combined with chemotherapy and to PARPi plus Bevacizumab. Finally, a significant increase in severe high blood pressure occurrence was observed when PARPi was added to antiangiogenetics, compared to PARPi alone but a significant decrease in G3-G4 hypertension occurrence was found in PARPi plus bevacizumab users compared to Bevacizumab alone.

CONCLUSIONS

PARPi are a valid option for the treatment of both primary and relapsed OC patients, with a relative low incidence of severe side effects.

PARP inhibitor cyanine dye conjugate with enhanced cytotoxic and antiproliferative activity in patient derived glioblastoma cell lines

We describe the synthesis and in vitro activity of drug-dye conjugate 1, which is a combination of the PARP inhibitor rucaparib and heptamethine cyanine dye IR-786. The drug-dye conjugate 1 was evaluated in three different patient-derived glioblastoma cell lines and showed strong cytotoxic activity with nanomolar potency (EC₅₀: 128 nM), which was a 780 fold improvement over rucaparib itself. We also observe a synergistic effect of 1 with temozolomide (TMZ), the standard drug for treatment for glioblastoma even though these cell lines were resistant to TMZ treatment. We envisage such conjugates to be worth exploring for their utility in the treatment of various brain cancers.

Radioimmunotherapy of human pancreatic cancer xenografts in NOD-scid mice with [64Cu]Cu-NOTA-panitumumab F(ab')2 alone or combined with radiosensitizing gemcitabine and the PARP inhibitor, rucaparib

INTRODUCTION

Our objective was to determine the feasibility of extending our previously reported PET imaging study of pancreatic cancer (PnCa) with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ to radioimmunotherapy (RIT) by exploiting the β-particle and Auger electron emissions of ⁶⁴Cu (PET theranostic concept). To enhance the effectiveness of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂, we further combined RIT with radiosensitizing gemcitabine (GEM) and the poly(ADP)ribose polymerase inhibitor (PARPi), rucaparib.

METHODS

Normal tissue toxicity was assessed in non-tumor-bearing NOD-scid mice injected i.v. with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (1.85-9.25 MBq; 10 μg) or [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ (12.95 MBq). Body weight was monitored, and hematopoietic (CBC), liver (ALT) and kidney [creatinine (SCr)] toxicity were assessed. RIT studies were performed in NOD-scid mice with s.c. OCIP23 human PnCa patient-derived xenografts (PDX) administered [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (3.7 MBq; 10 μg), unlabeled panitumumab F(ab')₂ (10 μg) or normal saline every two weeks. Subsequent studies evaluated RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) administered alone or combined with GEM and the PARPi, rucaparib administered on a 14-day treatment cycle for up to 6 cycles in NOD-scid mice with s.c. PANC-1 human PnCa xenografts. The radiation absorbed dose in PANC-1 tumors and normal organs in mice after a single i.v. injection of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) was estimated based on previously reported biodistribution studies of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂.

RESULTS

No normal tissue toxicity was observed in non-tumor-bearing NOD-scid mice administered up to 3.7 MBq (10 μg) of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ but slightly increased ALT was noted at 9.25 MBq. Administration of [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ (12.95 MBq; 10 μg) caused some hematopoietic toxicity but no increase in ALT or SCr or decreased body weight. A slight tumor growth delay and increased survival was noted in NOD-scid mice with s.c. OCIP23 PDX treated with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (3.7 MBq; 10 μg) or unlabeled panitumumab F(ab')₂ (10 μg) compared to normal saline treated mice. RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) combined with GEM + PARPi for up to 6 cycles was most effective for the treatment of PANC-1 tumors. Tumor doubling time increased to 13.3 ± 0.9 days vs. 7.8 ± 3.7 days for RIT alone and 9.3 ± 2.2 days for normal saline treatment. Median survival was significantly longer (P < 0.05) than in mice treated with normal saline (35 days) for RIT + GEM + PARPi (71 days), GEM + PARPi (44 days) and RIT + GEM (43 days) but not for RIT alone (25 days). RIT + GEM + PARPi provided a longer median survival than RIT (P < 0.01), GEM + PARPi (P = 0.01) but not RIT + GEM (P = 0.23). Nonetheless, PANC-1 tumors grew exponentially in all treatment groups. The absorbed dose in PANC-1 tumors after a single i.v. injection of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.85 MBq; 10 μg) was 0.8 Gy, while the dose in normal organs ranged from 0.6-1.2 Gy.

CONCLUSIONS

We conclude that RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ did not cause significant normal tissue toxicity but was not effective when administered alone for treatment of PnCa xenografts in NOD-scid mice. Combining RIT with GEM and the PARPi, rucaparib enhanced its effectiveness but tumors continued to grow exponentially. Our results suggest that ⁶⁴Cu is not feasible for RIT of PnCa due to low tumor absorbed doses. ¹⁷⁷Lu which has a higher abundance of moderate energy β-particle emissions may be more effective than ⁶⁴Cu. The hematopoietic toxicity of [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ may be mediated by binding to mouse EGFR expressed on some hematopoietic stem cells.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

Direct extension of PET with ⁶⁴Cu(Cu)-NOTA-panitumumab F(ab')₂ to RIT exploiting the β-particle and Auger electron emissions of ⁶⁴Cu is not feasible. Theranostic approaches that combine PET with RIT employing ¹⁷⁷Lu may be more promising and should be explored.

Development and validation of an integrated LC-MS/MS assay for therapeutic drug monitoring of five PARP-inhibitors

An liquid chromatography-mass spectrometry (LC-MS/MS) assay was developed for the combined analysis of the five poly (ADP-ribose) polymerase (PARP) inhibitors niraparib, olaparib, rucaparib talazoparib and veliparib. A simple and fast sample pre-treatment method was used by protein precipitating of plasma samples with acetonitrile and dilution of the supernatant with formic acid (0.1% v/v in water). This was followed by chromatographic separation on a reversed-phase UPLC BEH C18 column and detection with a triple quadrupole mass spectrometer operating in the positive mode. A simplified validation procedure specifically designed for bioanalytical methods for clinical therapeutic drug monitoring (TDM) purposes, was applied. This included assessment of the calibration model, accuracy and precision, lower limit of quantification (LLOQ), specificity and selectivity, carry-over and stability. The validated range was 30-3000 ng/mL for niraparib, 100-10,000 ng/mL for olaparib, 50-5000 ng/mL for rucaparib, 0.5-50 ng/mL for talazoparib and 50-5000 for veliparib. All results were within the criteria of the US Food and Drug Administration (FDA) guidance and European Medicines Agency (EMA) guidelines on method validation. The assay has been successfully implemented in our laboratory.

Real-World Delivery of Rucaparib to Patients with Ovarian Cancer: Recommendations Based on an Integrated Safety Analysis of ARIEL2 and Study 10

Treatment options for women with recurrent ovarian cancer who have received two or more prior lines of chemotherapy have recently expanded with the U.S. Food and Drug Administration (FDA) and European Commission (EC) approvals of the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib. As more oncologists begin to use rucaparib and other PARP inhibitors as part of routine clinical practice, awareness of possible side effects and how to adequately manage toxicities is crucial. In this review, we summarize the safety and tolerability of rucaparib reported in an integrated safety analysis that supported the FDA's initial approval of rucaparib in the treatment setting. Additionally, drawing on clinical data and our personal experience with rucaparib, we provide our recommendations on the management of common side effects observed with rucaparib, including anemia, blood creatinine elevations, alanine aminotransferase and aspartate aminotransferase elevations, thrombocytopenia, gastrointestinal-related events (e.g., nausea, vomiting), and asthenia and fatigue. These side effects, many of which appear to be class effects of PARP inhibitors, are often self-limiting and can be managed with adequate interventions such as treatment interruption and/or dose reduction and the use of supportive therapies. Supportive therapies may include blood transfusions for patients with anemia, prophylactic medications to prevent nausea and vomiting, or behavioral interventions to mitigate fatigue. Understanding and appropriate management of potential side effects associated with rucaparib may allow patients with ovarian cancer to continue to benefit from rucaparib treatment. IMPLICATIONS FOR PRACTICE: Rucaparib was recently approved in the U.S. and European Union for use as treatment or maintenance for recurrent ovarian cancer. This review focuses on the safety and tolerability of rucaparib in the treatment setting. Similar side effects are observed in the maintenance setting. Drawing on the authors' clinical experience with rucaparib, rucaparib prescribing information, and published supportive cancer care guidelines, this review discusses how to optimally manage common rucaparib-associated side effects in patients with advanced ovarian cancer in the real-world oncology setting. Adequate management of such side effects is crucial for allowing patients with ovarian cancer to remain on treatment to receive optimal efficacy benefit.

Maintenance therapy for recurrent epithelial ovarian cancer: current therapies and future perspectives - a review

Epithelial ovarian cancer (EOC) is usually diagnosed late at an advanced stage. Though EOC initially responds to treatment, the recurrence rate is pretty high. The efficacy of different targeted therapies reduces with each recurrence. Hence there is need of effective maintenance therapy in recurrent EOC. Recently, polyADP-ribose polymerase (PARP) inhibitors (PARPi) have been approved both for initial treatment of EOC and as its maintenance treatment. PARPi have also been found to act regardless of BRCA status or homologous recombination (HR) deficiency. Several trials testing PARPi early in maintenance therapy are in progress and their results will shed light on the optimal timing of maintenance therapy that gives the most benefit with least toxicity. Right patient selection for maintenance treatment is also a challenge. Hence, though PARPi are emerging as a promising maintenance treatment in recurrent EOC with prolongation of progression free survival (PFS), results from further trials and overall survival (OS) data from current trials are awaited to fulfill the gaps in understanding the role of this pathway in treatment of EOC. This review discusses the current therapies for EOC, challenges in the treatment of recurrent EOC, recent developments and trials in recurrent EOC maintenance with special focus on PARPi and future perspectives.

Evaluation of absorption, distribution, metabolism, and excretion of [14C]-rucaparib, a poly(ADP-ribose) polymerase inhibitor, in patients with advanced solid tumors

Rucaparib, a poly(ADP-ribose) polymerase inhibitor, is licensed for use in recurrent ovarian, fallopian tube, or primary peritoneal cancer. We characterized the absorption, distribution, metabolism, and elimination of rucaparib in 6 patients with advanced solid tumors following a single oral dose of [¹⁴C]-rucaparib 600 mg (≈140 μCi). Total radioactivity (TRA) in blood, plasma, urine, and feces was measured using liquid scintillation counting. Unchanged rucaparib concentrations in plasma were determined using validated liquid chromatography with tandem mass spectrometry. Maximum concentration (C_max) of TRA and unchanged rucaparib in plasma was 880 ng Eq/mL and 428 ng/mL, respectively, at approximately 4 h post dose; terminal half-life was >25 h for both TRA and rucaparib. The plasma TRA-time profile was parallel to yet higher than that of rucaparib, suggesting the presence of metabolites in plasma. Mean blood:plasma ratio of radioactivity was 1.0 for C_max and 0.8 for area under the concentration-time curve from time zero to infinity. Mean postdose recovery of TRA was 89.3% over 12 days (71.9% in feces; 17.4% in urine). Unchanged rucaparib and M324 (oxidative metabolite) were the major components in plasma, contributing to 64.0% and 18.6% of plasma radioactivity, respectively. Rucaparib and M324 were the major rucaparib-related components (each ≈7.6% of dose) in urine, whereas rucaparib was the predominant component (63.9% of dose) in feces. The high fecal recovery of unchanged rucaparib could be attributed to hepatic excretion and/or incomplete oral absorption. Overall, these data suggest that rucaparib is eliminated through multiple pathways, including metabolism and renal and biliary excretion.

Rucaparib in the landscape of PARP inhibition in ovarian cancer

Introduction: The landscape of poly (ADP-ribose) polymerase (PARP) inhibition in ovarian cancer is rapidly evolving and becoming increasingly complex. Ovarian cancer is leading therapeutic innovation by providing the proof of concept for DNA repair as a target. Three different PARP inhibitors have now received approvals in the US and Europe in different indications. Subtle but crucial differences can be found among the licensed indications for each PARP inhibitor in terms of histology, type of BRCA mutation (germline and/or somatic), number of prior lines of chemotherapy and whether the indication is in the treatment or maintenance settings. Areas covered: We review the latest clinical data regarding the PARP inhibitor rucaparib in ovarian cancer, provide an update on the evolving landscape of PARP inhibition in ovarian cancer, and summarize avenues of ongoing and future research. Expert opinion: All eligible patients should be offered a PARP inhibitor. SOLO1 trial results demonstrated an unprecedented benefit maintenance with PARP inhibitors in first line. Results from trials evaluating PARP inhibitors as maintenance in first line regardless of BRCA status and from trials evaluating combinatorial strategies are eagerly awaited.

Sensitization of colorectal cancer to irinotecan therapy by PARP inhibitor rucaparib

Intended to explore synthetic lethality and develop better combinatorial regimens, we screened colorectal cancer (CRC) cells using poly ADP-ribose (PAR) polymerase (PARP) inhibitors and cytotoxic agents. We studied four PARP inhibitors and three DNA-damaging agents, and their combinations using sulforhodamine B assay. Rucaparib demonstrated the greatest synergy with irinotecan, followed by olaparib and PJ34. Rucaparib and irinotecan was further subjected to detailed examination to determine combination index (CI) and underlying mechanism of action. Effectiveness and sequence dependence of this combination were assessed in microsatellite stable (MSS) and unstable (MSI) CRC and HCT116 isogenic cell lines. The degree of cell cycle arrest and apoptosis was determined by FACS. In vivo studies were performed to confirm efficacy of this combination. PAR levels in MSI and PARP expression in MSI and MSS cell lines were diminished upon combinatorial treatment. HCT116 isogenic cells revealed the importance of p21, p53 and PTEN in exerting synergy. In MSI cells, administration of rucaparib prior to irinotecan enhanced cytotoxicity compared to other strategies explored. FACS revealed S-phase arrest and increased late-stage apoptosis in MSS, and G2-M arrest and total and early-stage apoptosis in MSI cells. In in vivo murine xenograft models, a significant reduction in tumor volume and expression of Ki67, pancytokeratin and RPS6KB1, and increase in expression of caspase 3 were observed with the combination. In conclusion, among the various combinations studied, rucaparib plus irinotecan was the most synergistic one. Alterations in cell cycle arrest and apoptosis were dependent on MSI status in CRC cells.

How safe is rucaparib in ovarian cancer?

Introduction: Rucaparib is increasingly being utilized for women with recurrent ovarian cancer both as treatment and maintenance therapy. Poly-ADP ribose polymerase (PARP) inhibitors like rucaparib are daily oral medication that exploit the DNA repair pathway. The most significant clinical benefit is in those tumors exhibiting deficiency in their homologous recombination pathway. Areas covered: This review will discuss the mechanism of action, clinical efficacy data, and safety of rucaparib as presented from phase 1, 2, and 3 clinical trials. Expert opinion: Rucaparib is a promising therapeutic option for women where prolongation of survival with favorable side effects is the goal. The side effect profile of rucaparib is similar or more favorable when evaluating it against other PARP inhibitors. Physicians will likely need to have increasing comfort with unique side effects like transaminitis and serum creatinine increases. Clinicians should be prepared for not only increasing utilization of PARP inhibitors in the recurrent setting but also upfront usage may be on the horizon. As >50% of high grade serous ovarian cancers likely have the predictive biomarker, HRD, for PARP inhibition a substantial group of patients stand to have PARP inhibitors as part of their oncologic care.

Poly(ADP-ribose) Polymerase in Neurodegeneration: Radiosynthesis and Radioligand Binding in ARC-SWE tg Mice

We report the synthesis, radiosynthesis, and characterization of a radioligand for poly(ADP-ribose) polymerase (PARP). PARP is of central importance in cell homeostasis, neuroplasticity, and neurodegeneration in the brain. A radiolabeled PARP inhibitor was developed and used for autoradiographic quantification of PARP protein concentration in wild-type and transgenic rodent brains ex vivo in high resolution. The binding of [³H]rucaparib was found to be confined to PARP-expressing domains, for example, cerebellar cortex or hippocampal regions in both models. Saturation binding experiments confirmed selective and reversible binding to a single site ( K_d = 1.1 ± 0.2 nM).

Rucaparib: An emerging parp inhibitor for treatment of recurrent ovarian cancer

Recently, Poly-ADP-Ribose Polymerase (PARP) inhibitors are one of the most intensively studied group of antiblastic agents for the management of recurrent ovarian cancer. Among this family, Olaparib was the first to be approved by European Medicines Agency as maintenance therapy post-response to platinum-based chemotherapy for recurrent ovarian cancer in women with deleterious BRCA1/2 mutation. Following that, the Food and Drug Administration (FDA) approved Olaparib monotherapy as fourth or later line of treatment in advanced ovarian cancer with deleterious germ-line BRCA1/2 mutation. On March 2017, Niraparib, was approved as maintenance treatment of patients with recurrent epithelial ovarian, who are in complete or partial response to platinum-based chemotherapy, independently of BRCA mutation. Rucaparib inhibits PARP-1, 2 and 3, PARP-4, -12, -15 and -16, as well as tankyrase 1 and 2. On December 2016, it was granted accelerated approval by the FDA, based on data from two multicenter, single arm, phase II trials that evaluated the efficacy of Rucaparib in patients with deleterious, germline and/or somatic BRCA mutation-associated, advanced OC, who have been treated with two or more lines of chemotherapy. The maximum tolerated dose reported was 600 mg twice a day administered orally. Phase III studies are currently ongoing to further validate the efficacy of Rucaparib in the treatment setting and explore its usefulness in a maintenance setting as well. The focus of our review is to report the most recent investigations and clinical progress regarding Rucaparib for treatment of recurrent ovarian cancer.

The promising PARP inhibitors in ovarian cancer therapy: From Olaparib to others

Epithelial ovarian cancer (EOC) accounts for 90% of all ovarian cancer. Initially, approaching 80% of EOC patients respond to standard therapeutic strategy, cytoreduction combining with postoperative auxiliary platinum-based chemotherapy. However, relapse is approximately inevitable because of drug-resistance for high-grade serous ovarian cancer (HGSOC). Recently, the nuclear enzyme poly (ADP-ribose) polymerase (PARP) represents a strikingly novel target in EOC treatment. PARP inhibitors, currently mainly including Olaparib, Niraparib, Velaparib, Rucaparib, and Talazoparib, have demonstrated promising activity in EOC treatment. Especially, studies of Olaparib accelerated it to be approved in Europe and USA. Here, this review focuses on the pre-clinical data, current clinical trials, the development of PARP inhibitors in the last decade and their future roles in clinical treatment for EOC patients.

Antitumor activity and safety of the PARP inhibitor rucaparib in patients with high-grade ovarian carcinoma and a germline or somatic BRCA1 or BRCA2 mutation: Integrated analysis of data from Study 10 and ARIEL2

OBJECTIVE

An integrated analysis was undertaken to characterize the antitumor activity and safety profile of the oral poly(ADP-ribose) polymerase inhibitor rucaparib in patients with relapsed high-grade ovarian carcinoma (HGOC).

METHODS

Eligible patients from Study 10 (NCT01482715) and ARIEL2 (NCT01891344) who received a starting dose of oral rucaparib 600mg twice daily (BID) with or without food were included in these analyses. The integrated efficacy population included patients with HGOC and a deleterious germline or somatic BRCA1 or BRCA2 (BRCA1/2) mutation who received at least two prior chemotherapies and were sensitive, resistant, or refractory to platinum-based chemotherapy. The primary endpoint was investigator-assessed confirmed objective response rate (ORR). Secondary endpoints included duration of response (DOR) and progression-free survival (PFS). The integrated safety population included patients with HGOC who received at least one dose of rucaparib 600mg BID, irrespective of BRCA1/2 mutation status and prior treatments.

RESULTS

In the efficacy population (n=106), ORR was 53.8% (95% confidence interval [CI], 43.8-63.5); 8.5% and 45.3% of patients achieved complete and partial responses, respectively. Median DOR was 9.2months (95% CI, 6.6-11.6). In the safety population (n=377), the most frequent treatment-emergent adverse events (AEs) were nausea, asthenia/fatigue, vomiting, and anemia/hemoglobin decreased. The most common grade ≥3 treatment-emergent AE was anemia/hemoglobin decreased. Treatment-emergent AEs led to treatment interruption, dose reduction, and treatment discontinuation in 58.6%, 45.9%, and 9.8% of patients, respectively. No treatment-related deaths occurred.

CONCLUSIONS

Rucaparib has antitumor activity in advanced BRCA1/2-mutated HGOC and a manageable safety profile.