A Phase II Study of Rucaparib Monotherapy in Nonmetastatic, Hormone-Sensitive Prostate Cancer Demonstrating "BRCAness" Genotype (ROAR).

BACKGROUND: Both germline and somatic BReast CAncer gene (BRCA) mutations are poor prognostic markers in men with localized or metastatic prostate cancer. For instance, men with these mutations often are diagnosed with prostate cancer earlier and develop metastatic disease earlier compared with those who do not harbor similar mutations. Patients with germline alterations typically have more advanced disease and shorter overall survival (Castro E, Goh C, Olmos D, et al. Germline BRCA mutations are associated with higher risk of nodal involvement, distant metastasis, and poor survival outcomes in prostate cancer. J Clin Oncol. 2013;31(14):1748-1757. doi:10.1200/JCO.2012.43.1882). The risk of disease progression to metastatic disease is significant in patients with this genotype of prostate cancer. The percentage of patients free from metastatic disease was 90%, 72%, and 50%, respectively, compared with 97%, 94%, and 84% at 3, 5, and 10 years for patients with intact DNA repair (P < .001) (Castro E, Goh C, Leongamornlert D, et al. Effect of BRCA mutations on metastatic relapse and cause-specific survival after radical treatment for localised prostate cancer. Eur Urol. 2015;68(2):186-193. doi: 10.1016/j.eururo.2014.10.022). DNA damage repair non-BRCA mutations include alterations in genes such as ATM, CHEK2, PALB2, and RAD51. While less common than BRCA mutations, they have emerged as significant prognostic markers in prostate cancer. These BRCAness mutations are associated with a higher risk of aggressive disease and poorer survival outcomes. Given the debilitating physical and psychological side effects of androgen deprivation therapy (ADT) in relatively younger men with prostate cancer, delaying ADT in these men may be an attractive strategy. Given the proven efficacy of polyadenosine diphosphate-ribose polymerase (PARP) inhibitors in the castration-resistant prostate cancersetting, PARP inhibitor monotherapy in a nonmetastatic castration-sensitive (nmCSPC) setting has the potential to delay metastasis and delay the onset of ADT related symptoms. METHODS: This is a single-arm, single-center, open-label, phase II trial to assess the efficacy of rucaparib in patients with high-risk biochemically recurrent (BCR) nmHSPC, which was defined as PSA doubling time of <9 months, demonstrating a "BRCAness" genotype (BRCA1/2 and other homologous recombination repair mutations). A total of 15 patients were intended to be enrolled, with an expected enrollment duration of 12 months. Patients were given rucaparib 600 mg orally twice daily and were allowed to remain on study treatment until PSA progression defined by Prostate Cancer Working Group 3, with 2 years of follow-up after study treatment. We anticipated a total of 2-3 years until completion of the clinical trial. The primary endpoint was to assess the PSA progression-free survival (PSA-PFS). The secondary endpoints of the study were safety, the proportion of patients with a PSA 50% response (PSA 50), and an undetectable PSA. A 4-week treatment duration comprised one cycle. RESULTS: The study started enrolling in June 2019 and was prematurely terminated in June 2022 after the accrual of 7 patients because of changing standard of care treatments with the introduction of next-generation scans, eg, prostate-specific membrane antigen positron emission tomography (PSMA-PET). Seven patients were enrolled in the study with the following pathogenic alterations: ATM (n = 3), BRCA2 (n = 2), BRCA1 (n = 1), BRIP1 (n = 1), and RAD51 (n = 1). The median duration of follow-up was 18 months. A median of 20 cycles (range 4-42) was completed, median PSA-PFS was 35.37 months (95% CI, 0-85.11 months). In total, 2 patients achieved PSA50; both also achieved nadir PSA as undetectable. Grade ≥ 3 adverse events (AEs) were anemia and rash (in 1 patient each). No dose-limiting toxicities or severe AEs were seen. CONCLUSION: Rucaparib demonstrated acceptable toxicity and efficacy signal as an ADT-sparing approach in patients with biochemically recurrent nonmetastatic prostate cancer. It is currently challenging to understand the optimal value of systemic therapy in this disease setting due to the rapidly changing standard of care. Additionally, there are relatively few patients with BRCAness who present with nonmetastatic hormone-sensitive prostate cancer (ClinicalTrials.gov Identifier: NCT03533946).

Cytostatic Bacterial Metabolites Interfere with 5-Fluorouracil, Doxorubicin and Paclitaxel Efficiency in 4T1 Breast Cancer Cells.

The microbiome is capable of modulating the bioavailability of chemotherapy drugs, mainly due to metabolizing these agents. Multiple cytostatic bacterial metabolites were recently identified that have cytostatic effects on cancer cells. In this study, we addressed the question of whether a set of cytostatic bacterial metabolites (cadaverine, indolepropionic acid and indoxylsulfate) can interfere with the cytostatic effects of the chemotherapy agents used in the management of breast cancer (doxorubicin, gemcitabine, irinotecan, methotrexate, rucaparib, 5-fluorouracil and paclitaxel). The chemotherapy drugs were applied in a wide concentration range to which a bacterial metabolite was added in a concentration within its serum reference range, and the effects on cell proliferation were assessed. There was no interference between gemcitabine, irinotecan, methotrexate or rucaparib and the bacterial metabolites. Nevertheless, cadaverine and indolepropionic acid modulated the Hill coefficient of the inhibitory curve of doxorubicin and 5-fluorouracil. Changes to the Hill coefficient implicate alterations to the kinetics of the binding of the chemotherapy agents to their targets. These effects have an unpredictable significance from the clinical or pharmacological perspective. Importantly, indolepropionic acid decreased the IC50 value of paclitaxel, which is a potentially advantageous combination.

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.

Real-World Efficacy and Safety of PARP Inhibitors in Recurrent Ovarian Cancer Patients With Somatic BRCA and Other Homologous Recombination Gene Mutations.

BACKGROUND: Real-world data regarding the use of poly (ADP-ribose) polymerase (PARP) inhibitors in recurrent ovarian cancer patients with non-BRCA homologous recombination (HR) mutations or somatic BRCA mutations are lacking. OBJECTIVE: The purpose of our study is to evaluate the response rate, duration of treatment, time to progression (TTP), and toxicities of olaparib, niraparib, and rucaparib in somatic BRCAm and non-BRCA HR-mutated patients. METHODS: This was a retrospective study using the electronic medical record to identify patients across our health system who were initiated on a PARP inhibitor for ovarian cancer between December 2014 and December 2019. Patients were screened for the presence of a somatic BRCA1/2 mutation or a mutation in non-BRCA HR genes. Data were collected via chart review. RESULTS: For the efficacy analysis, 8 patients had somatic BRCA mutations and 12 patients had HR mutations. The overall response rate (ORR) was 50% for BRCA-mutated (BRCAm) patients and 9.1% for non-BRCA HR-mutated (non-BRCA HRm) patients. 72.7% of patients with non-BRCA HR mutations had stable disease. The duration of therapy ranged from 2 to 66 months. The median TTP was 9.5 months. Overall, 66.7% of patients in the entire cohort started on a reduced dose of PARP inhibitor. Dose reductions due to AEs were observed in 52.4% of patients, while AEs requiring treatment interruption occurred in 61.9%. CONCLUSION AND RELEVANCE: We found that PARP inhibitors provided stable disease in a high proportion of recurrent ovarian cancer patients who had pathogenic HR mutations, with toxicities comparable to major trials. Patients with non-BRCA HR and somatic BRCA mutations could benefit from PARP inhibitors.

Attenuation of Tumor Burden in Response to Rucaparib in Lung Adenocarcinoma: The Contribution of Oxidative Stress, Apoptosis, and DNA Damage.

In cancer, overactivation of poly (ADPribose) polymerases (PARP) plays a relevant role in DNA repair. We hypothesized that treatment with the PARP inhibitor rucaparib may reduce tumor burden via several biological mechanisms (apoptosis and oxidative stress) in mice. In lung tumors (LP07 lung adenocarcinoma) of mice treated/non-treated (control animals) with PARP inhibitor (rucaparib,150 mg/kg body weight/24 h for 20 day), PARP activity and expression, DNA damage, apoptotic nuclei, cell proliferation, and redox balance were measured using immunoblotting and immunohistochemistry. In lung tumors of rucaparib-treated mice compared to non-treated animals, tumor burden, PARP activity, and cell proliferation decreased, while DNA damage, TUNEL-positive nuclei, protein oxidation, and superoxide dismutase content (SOD)2 increased. In this experiment on lung adenocarcinoma, the pharmacological PARP inhibitor rucaparib elicited a significant improvement in tumor size, probably through a reduction in cell proliferation as a result of a rise in DNA damage and apoptosis. Oxidative stress and SOD2 also increased in response to treatment with rucaparib within the tumor cells of the treated mice. These results put the line forward to the contribution of PARP inhibitors to reduced tumor burden in lung adenocarcinoma. The potential implications of these findings should be tested in clinical settings of patients with lung tumors.

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.

Rucaparib in recurrent ovarian cancer: real-world experience from the rucaparib early access programme in Spain - A GEICO study.

BACKGROUND: Rucaparib is a poly(ADP-ribose) polymerase inhibitor approved in Europe as maintenance therapy for recurrent platinum-sensitive (Pt-S) ovarian cancer (OC). The Rucaparib Access Programme (RAP) was designed to provide early access to rucaparib for the above-mentioned indication, as well as for patients with BRCA-mutated Pt-S or platinum-resistant (Pt-R) OC and no therapeutic alternatives. METHODS: In this observational, retrospective study we analysed the efficacy and safety of rucaparib within the RAP in Spain. Hospitals associated with the Spanish Ovarian Cancer Research Group (GEICO) recruited patients with high-grade epithelial ovarian, fallopian tube, or primary peritoneal cancer treated with rucaparib 600 mg twice daily as maintenance or treatment (Pt-S/Pt-R) in the RAP. Baseline characteristics, efficacy, and safety data were collected. RESULTS: Between July 2020 and February 2021, 51 patients treated in 22 hospitals in the RAP were included in the study. Eighteen patients with a median of 3 (range, 1-6) prior treatment lines received rucaparib as maintenance; median progression-free survival (PFS) for this group was 9.1 months (95% confidence interval [CI], 4.2-11.6 months). Among 33 patients (median 5 [range, 1-9] prior treatment lines) who received rucaparib as treatment, 7 and 26 patients had Pt-S and Pt-R disease, respectively. Median PFS was 10.6 months (95% CI, 2.5 months-not reached) in the Pt-S group and 2.2 months (95% CI, 1.1-3.2 months) in the Pt-R group. Grade ≥ 3 treatment-emergent adverse events were reported in 39% of all patients, the most common being anaemia (12% and 15% in the maintenance and treatment groups, respectively). At data cut-off, 5 patients remained on treatment. CONCLUSION: Efficacy results in these heavily pre-treated patients were similar to those from previous trials. The safety profile of rucaparib in real life was predictable and manageable.

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.

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.

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.

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.

Evaluation of the management of PARP inhibitor toxicities in ovarian and endometrial cancer within a multi-institution health-system.

INTRODUCTION: Poly-adenosine diphosphate ribose polymerase inhibitors (PARPi) have become a cornerstone of therapy in the management ovarian cancer and other cancers. PARPi are associated with significant toxicities and management strategies are primarily founded on clinical trial experience. This study aimed to provide an evaluation of patients receiving PARPi therapy within an academic health-system. METHODS: A retrospective, observational study of adult patients with gynecologic malignancy was conducted at the University of Pennsylvania Health System. Data was collected on patients prescribed a PARPi between December 2014 and October 2019. The primary endpoint was the status of PARPi therapy at the end of the study period. Key secondary endpoints included toxicity management strategies, time to discontinuation due to toxicity, progression free survival (PFS), and overall survival (OS). RESULTS: Of the 85 patients included, 45 (53%) received olaparib, 24 (28%) niraparib, and 16 (19%) rucaparib. Twenty-nine patients (34%) continued on therapy, 15 (18%) discontinued due to toxicity, and 41 (48%) discontinued due to progression. Fifty-one percent of patients required a dose reduction due to toxicities. The median time to discontinuation due to toxicity was 69 days (9-353). Median PFS was 181 days (9-365) and median OS was 338 days (9-365). CONCLUSION: PARPi therapy is associated with numerous toxicities that are best managed through a multi-modal approach. Importantly, about half the patients in the current study required a dose reduction. Overall, this observational study outlines the incidence of PARPi toxicities and reviews potential management strategies, further guiding practitioners in an area with limited real-world experience.

Rucaparib and olaparib for the treatment of prostate cancer: A clinician's guide to choice of therapy.

OBJECTIVE: This review will provide an overview of the use rucaparib and olaparib in patients with metastatic castration resistant prostate cancer (mCRPC) with the goal to assist the clinician's decision-making process when considering these agents for an individual patient. DATA SOURCES: Searches were conducted in PubMed, relevant meeting abstracts, clinicaltrials.gov, and United States Food and Drug Administration (FDA) documents to identify literature published through July 1, 2021, related to use of rucaparib and olaparib for treatment of prostate cancer. DATA SUMMARY: In May 2020, the FDA approved rucaparib and olaparib for treatment of mCRPC that is homologous recombination repair (HRR)-deficient. Both agents are approved for previously-treated patients, but there are notable differences in strength of evidence, outcomes studied, required HRR alteration, and required prior therapies. In patients who qualify for therapy, additional factors that may help guide choice of PARP inhibitor include baseline organ function, drug interaction potential, toxicity profiles, and financial factors. CONCLUSIONS: Rucaparib and olaparib have the potential to improve outcomes for patients with HRR-deficient mCRPC. Differences in strength of evidence and patient- and drug-specific characteristics will assist the clinician when choosing between agents.

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.HIGHLIGHTSStructural 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.

Comparative Analyses of Poly(ADP-Ribose) Polymerase Inhibitors.

Poly(ADP-ribose) polymerase inhibitors (PARPi) are approved as monotherapies in BRCA1/2-mutated (mBRCA1/2) metastatic breast and ovarian cancers, and in advanced pancreatic and metastatic castration-resistant prostate cancers. Differential safety profiles across PARPi necessitate improved mechanistic understanding of inhibitor differences, especially with expansion of PARPi indications and drug combinations. Here, we report in vitro evaluations of PARPi (-/+ PARP trapper temozolomide, TMZ) with reference to total clinical mean concentration average or maximum (tCavg, tCmax), to elucidate contributions of primary pharmacology and structural differences to clinical efficacy and safety. In biochemical assays, rucaparib and niraparib demonstrated off-target secondary pharmacology activities, and in selectivity assays, talazoparib, olaparib, and rucaparib inhibited a broader panel of PARP enzymes. In donor-derived human bone marrow mononuclear cells, only olaparib both increased early apoptosis and decreased the cell viability half inhibitory concentration (IC50) at ≤ tCavg, whereas other PARPi only did so in the presence of TMZ. In cancer cell lines with DNA damage repair mutations, all PARPi decreased cell viability in H1048 but not TK6 cells, and only talazoparib decreased cell growth in DU145 cells at ≤ tCavg concentrations. When combined with low dose TMZ, only talazoparib left-shifted the functional consequences of PARP trapping (S-phase arrest, apoptosis, S-phase double-stranded breaks) and reduced cell viability/growth in TK6 and DU145 cell lines at ≤ tCavg, whereas the other inhibitors required high-dose TMZ. Our study suggests structural differences across PARPi may contribute to differences in PARP selectivity and off-target activities, which along with distinct pharmacokinetic properties, may influence inhibitor-specific toxicities in patients.

The Molecular Mechanisms of Actions, Effects, and Clinical Implications of PARP Inhibitors in Epithelial Ovarian Cancers: A Systematic Review.

Ovarian cancer is the most lethal gynecologic malignancy in the United States. Some patients affected by ovarian cancers often present genome instability with one or more of the defects in DNA repair pathways, particularly in homologous recombination (HR), which is strictly linked to mutations in breast cancer susceptibility gene 1 (BRCA 1) or breast cancer susceptibility gene 2 (BRCA 2). The treatment of ovarian cancer remains a challenge, and the majority of patients with advanced-stage ovarian cancers experience relapse and require additional treatment despite initial therapy, including optimal cytoreductive surgery (CRS) and platinum-based chemotherapy. Targeted therapy at DNA repair genes has become a unique strategy to combat homologous recombination-deficient (HRD) cancers in recent years. Poly (ADP-ribose) polymerase (PARP), a family of proteins, plays an important role in DNA damage repair, genome stability, and apoptosis of cancer cells, especially in HRD cancers. PARP inhibitors (PARPi) have been reported to be highly effective and low-toxicity drugs that will tremendously benefit patients with HRD (i.e., BRCA 1/2 mutated) epithelial ovarian cancer (EOC) by blocking the DNA repair pathways and inducing apoptosis of cancer cells. PARP inhibitors compete with NAD+ at the catalytic domain (CAT) of PARP to block PARP catalytic activity and the formation of PAR polymers. These effects compromise the cellular ability to overcome DNA SSB damage. The process of HR, an essential error-free pathway to repair DNA DSBs during cell replication, will be blocked in the condition of BRCA 1/2 mutations. The PARP-associated HR pathway can also be partially interrupted by using PARP inhibitors. Grossly, PARP inhibitors have demonstrated some therapeutic benefits in many randomized phase II and III trials when combined with the standard CRS for advanced EOCs. However, similar to other chemotherapy agents, PARP inhibitors have different clinical indications and toxicity profiles and also face drug resistance, which has become a major challenge. In high-grade epithelial ovarian cancers, the cancer cells under hypoxia- or drug-induced stress have the capacity to become polyploidy giant cancer cells (PGCCs), which can survive the attack of chemotherapeutic agents and start endoreplication. These stem-like, self-renewing PGCCs generate mutations to alter the expression/function of kinases, p53, and stem cell markers, and diploid daughter cells can exhibit drug resistance and facilitate tumor growth and metastasis. In this review, we discuss the underlying molecular mechanisms of PARP inhibitors and the results from the clinical studies that investigated the effects of the FDA-approved PARP inhibitors olaparib, rucaparib, and niraparib. We also review the current research progress on PARP inhibitors, their safety, and their combined usage with antiangiogenic agents. Nevertheless, many unknown aspects of PARP inhibitors, including detailed mechanisms of actions, along with the effectiveness and safety of the treatment of EOCs, warrant further investigation.

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.

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.

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).