Personalized Treatment Approach to Metastatic Castration-Resistant Prostate Cancer with BRCA2 and PTEN Mutations: A Case Report

DNA repair mutations (BRCA1 and BRCA2) are found in metastatic castration-resistant prostate cancer (CRPC) patients. Here, we report a case of a 71-year-old male patient with metastatic CRPC along with BRCA2 and PTEN mutations. As per the genomic findings of the Foundation One report, FDA-approved therapies were available for other tumor types, such as olaparib for the loss of BRCA2 and everolimus for the loss of PTEN exons 2-9. These findings were confirmed in another novel phenotypic assay that revealed the sensitivity of olaparib and carboplatin combination therapy. After 4 cycles, our patient achieved a partial response along with a good performance status.

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.

Sensitivity of Mesothelioma Cells to PARP Inhibitors Is Not Dependent on BAP1 but Is Enhanced by Temozolomide in Cells With High-Schlafen 11 and Low-O6-methylguanine-DNA Methyltransferase Expression

INTRODUCTION

BRCA1-associated protein-1 (BAP1), a nuclear deubiquitinase thought to be involved in DNA double-strand break repair, is frequently mutated in mesothelioma. Because poly(adenosine diphosphate-ribose) polymerase inhibitors (PARPIs) induce synthetic lethality in BRCA1/2 mutant cancers, we evaluated whether BAP1 inactivating mutations confer sensitivity to PARPIs in mesothelioma and if combination therapy with temozolomide (TMZ) would be beneficial.

METHODS

A total of 10 patient-derived mesothelioma cell lines were generated and characterized for BAP1 mutation status, protein expression, nuclear localization, and sensitivity to the PARPIs, olaparib, and talazoparib, alone or in combination with TMZ. BAP1 deubiquitinase (DUB) activity was evaluated by ubiquitin with 7-amido-4-methylcoumarin assay. BAP1 knockout mesothelioma cell lines were generated by CRISPR-Cas9. Because Schlafen 11 (SLFN11) and O⁶-methylguanine-DNA methyltransferase also drive response to TMZ and PARPIs, we tested their expression and relationship with drug response.

RESULTS

BAP1 mutations or copy-number alterations, or both were present in all 10 cell lines. Nonetheless, four cell lines exhibited intact DUB activity and two had nuclear BAP1 localization. Half maximal-inhibitory concentrations of olaparib and talazoparib ranged from 4.8 μM to greater than 50 μM and 0.039 μM to greater than 5 μM, respectively, classifying them into sensitive (two) or resistant (seven) cells, independent of their BAP1 status. Cell lines with BAP1 knockout resulted in the loss of BAP1 DUB activity but did not increase sensitivity to talazoparib. Response to PARPI tended to be associated with high SLFN11 expression, and combination with temozolomide increased sensitivity of cells with low or no MGMT expression.

CONCLUSIONS

BAP1 status does not determine sensitivity to PARPIs in patient-derived mesothelioma cell lines. Combination of PARPI with TMZ may be beneficial for patients whose tumors have high SLFN11 and low or no MGMT expression.

A phase 1 dose-escalation study of intraperitoneal cisplatin, intravenous/intraperitoneal paclitaxel, bevacizumab, and olaparib for newly diagnosed ovarian cancer

OBJECTIVE

We assessed the safety and maximum tolerated dose (MTD) of the poly ADP-ribose polymerase (PARP) inhibitor olaparib with intravenous (IV)/intraperitoneal (IP) cisplatin/paclitaxel and IV bevacizumab, followed by olaparib and bevacizumab maintenance, in patients with newly diagnosed ovarian cancer who had undergone primary debulking surgery.

METHODS

Treatment included: (Cycles 1-6) Day 1, IV paclitaxel 135 mg/m²/3 h + (from Cycle 2 onward) bevacizumab 15 mg/kg; Day 2, IP cisplatin 75 mg/m²; Days 2-8, olaparib (50/100/200 mg BID); Day 8, IP paclitaxel 60 mg/m² of a 21-day cycle. Maintenance (Cycles 7-22) included: olaparib 300 mg BID and bevacizumab 15 mg/kg Day 1. The primary endpoint was MTD of olaparib, chemotherapy, and bevacizumab.

RESULTS

Seventeen women were treated (Cohort 1 [50 mg olaparib], 8 patients; Cohort 2 [100 mg], 3 patients; and Cohort 3 [200 mg], 6 patients). Median age was 57 years (47-73); 94% had stage III disease; 29% had a germline BRCA mutation. Two of 6 patients in Cohort 3 experienced a dose-limiting toxicity (DLT). Grade 3/4 toxicities included: neutropenia (56%), lymphopenia (31%), anemia (25%), and fatigue (19%). Most patients started (88%, 81%) and completed (75%, 50%) maintenance olaparib and bevacizumab, respectively; 36% of patients on olaparib maintenance required a dose reduction. Median PFS was 33 months (26.2-NA).

CONCLUSIONS

The MTD of intermittently dosed olaparib with concurrent IV/IP cisplatin/paclitaxel and bevacizumab is 100 mg BID. Non-hematologic toxicities were predominantly low grade. One-third of patients on olaparib maintenance required dose reduction.

Rosiglitazone ameliorates senescence and promotes apoptosis in ovarian cancer induced by olaparib

OBJECTIVE

Senescence mechanisms are vital to resistance to long-term olaparib maintenance treatment. Recently, peroxisome proliferator-activated receptor-γ agonists (e.g., rosiglitazone) have been reported to ameliorate the senescence-like phenotype by modulating inflammatory mediator production. This study examined synergistic effects on the anti-tumor activity of rosiglitazone combined with olaparib in ovarian cancer treatment.

METHODS

A2780 and SKOV3 mouse subcutaneous xenograft models were established for observing anti-tumor effects in living organisms and were randomly split into combination (both olaparib and rosiglitazone), rosiglitazone (10 mg/kg), olaparib (10 mg/kg), control (solvent) groups that received treatment once every 2 or 3 days (n = 6 per group). Cell counting kit-8 (CCK-8) assays were used to test the influences of rosiglitazone and olaparib on cell proliferation. PI and Annexin-V-FITC staining was used with flow cytometry to assess the cell cycle distribution and cell apoptosis. Senescence-associated β-galactosidase (SA-β-Gal) staining was used to observe cellular senescence. We performed quantitative real-time polymerase chain reaction assays to study the senescence-related secretory phenotype (SASP).

RESULTS

Olaparib and rosiglitazone were observed to synergistically retard subcutaneous ovarian cancer growth in vivo, and synergistically suppress ovarian cancer cell proliferation in vitro. Compared with olaparib alone, the percentage of positive cells expressed SA-β-gal and SASP were significantly decreased in the treatment of combination of olaparib and rosiglitazone. Furthermore, olaparib plus rosiglitazone increased the percentage of apoptosis in ovarian cancer cell compared with olaparib alone. In A2780 cells, it showed lower expression of P53, phospho-p53 (Ser15), P21, and P18 protein in combination treatment compared with olaparib alone. While, in SKOV3 cells, it showed lower expression of phosphor-retinoblastoma protein (Rb) (Ser807/811), and higher expression of cyclin D1, P21, and P16 protein in combination treatment compared with olaparib alone.

CONCLUSIONS

Rosiglitazone combined with olaparib can help manage ovarian cancer by ameliorating olaparib-induced senescence and improving anti-tumor effects.

Experiencia con el uso de olaparib en pacientes con cáncer de ovario

Introduction

More than the twenty percent of ovarian cancers are hereditary, and most have BRCA mutations. The 30% of Mexican patients with the BRCA1 mutation have the BRCA1 gene exon 9-12del deletion founder mutation (BRCA1 ex9-12del). BRCA-mutated tumors are more sensitive to PARP inhibitors such as olaparib.

Objective

To show the clinical experience on the use of olaparib at Instituto Nacional de Cancerología in Mexico.

Method

Ovarian cancer patients treated with olaparib from November 2016 to December 2018 were studied, and their characteristics, clinical response, progression-free survival (PFS) and toxicities were described.

Results

Nineteen patients were assessed, with BRCA1 mutation being found in 78.9%, out of which 21.1% were carriers of the ex9-12del founder mutation. The median of PFS was 12 months; for patients treated on second and third line it was > 15 months, and for those treated with a fourth and subsequent line it was 8.3 months. Patients with the founder mutation had better results. Toxicities were like those reported in previous studies.

Conclusions

Olaparib offers greater PFS benefit as maintenance therapy after a first and second relapse. Patients with founder mutation have had sustained PFS.

Olaparib in the therapy of advanced ovarian cancer: first real world experiences in safety and efficacy from China

PURPOSE

Poly (ADP-ribose) polymerase (PARP) inhibitor, is a milestone in treatment of ovarian cancer. However, there is no real world study from China regarding the clinical outcome of the taking PARP inhibitor (PARPi), Olaparib(Lynparza™). The goal of this research is to evaluate the side effects and short-term efficacy in advanced ovarian cancer patients who administered Olaparib.

METHODS

Patients with ovarian cancer, fallopian tube cancer and peritoneal cancer that treated with Olaparib in The Affiliated Cancer Hospital of Nanjing Medical University between September 2018 and June 2019 were recruited. The drug associated Adverse Events (AEs) were collected and short-term efficacy were analyzed by modified Response Evaluation Criteria in Solid Tumors (mRECIST) .

RESULTS

Of all 28 enrolled patients, 92.9% were ovarian cancer, 7.1% were fallopian tube cancer, and 39.3% cases harbored germline BRCA-mutation. There were 6(21.4%) patients received Olaparib after multi-line chemotherapy, and 10 patients (35.7%) as second-line maintenance therapy and 2 patients (7.1%) as first-line maintenance therapy. There were still other 10 cases (35.7%) received Olaparib as exploratory therapy. Abdominal distention, decreased blood pressure, increased body hair, thirsty, burning sensation of stomach and leg swelling were newly reported AEs. Serious Adverse Events(SAEs) were usually managed by dose interruption or dose reduction, rather than discontinuation. 3 patients discontinued treatment, 8 patients received reduced dose of Olaparib, and 4 patients stopped therapy after the alleviation of AEs. Of all 28 enrolled cases, in monotherapy group, 1 of 6 patients achieved stable disease(SD) and also 2 patients achieved stable disease(SD) combined with anti-angiogenic drugs when disease progressed. 2 patients achieved complete remission(CR) and 3 patients were stable with exploratory therapy.

CONCLUSIONS

The AEs of Olaparib were all manageable. For the first time, we also identified several AEs such as abdominal distention, decreased blood pressure, increased body hair, thirsty, burning sensation of stomach and leg swelling during the follow-up which have not been reported. The short-term efficacy was observed in some exploratory cases that provided new potential indication to PARPi-related clinical trials.

Response of Estrogen-Receptor-Positive Metastatic Breast Cancer to Olaparib in Late-Line Therapy

Monotherapy with olaparib provides significant benefits over standard therapy in patients with a germline BRCA mutation and human epidermal growth factor receptor 2 (HER2) negative metastatic breast cancer, who had two or fewer previous chemotherapeutic regimens for metastatic disease. Olaparib was approved on July 2, 2018, in Japan for the treatment of patients with metastatic breast cancer with a BRCA mutation and HER2-negative status. Thus, the current experience with this drug is relatively limited. In this article, we report a case of luminal-type metastatic breast cancer harboring a BRCA1 mutation detected through BRACAnalysis (Myriad Genetics). Despite the late-line treatment, in this patient, olaparib was effective against metastatic breast cancer.

PARP inhibitor Olaparib Enhances the Apoptotic Potentiality of Curcumin by Increasing the DNA Damage in Oral Cancer Cells through Inhibition of BER Cascade

Although Olaparib (Ola, a PARP-inhibitor), in combination with other chemotherapeutic agents, was clinically approved to treat prostate cancer, but cytotoxicity, off-target effects of DNA damaging agents limit its applications in clinic. To improve the anti-cancer activity and to study the detailed mechanism of anti-cancer action, here we have used bioactive compound curcumin (Cur) in combination with Ola. Incubation of Ola in Cur pre-treated cells synergistically increased the death of oral cancer cells at much lower concentrations than individual optimum dose and inhibited the topoisomerase activity. Short exposure of Cur caused DNA damage in cells, but more increased DNA damage was noticed when Ola has incubated in Cur pre-treated cells. This combination did not alter the major components of homologous recombination (HR) and non-homologous end-joining (NHEJ) pathways but significantly altered both short patch (SP) and long patch (LP) base excision repair (BER) components in cancer cells. Significant reduction in relative luciferase activity, expression of BER components and PARylation after Cur and Ola treatment confirmed this combination inhibit the BER activity in cells. Reduction of PARylation, decreased expression of BER components, decreased tumor volume and induction of apoptosis were also noticed in Cur + Ola treated Xenograft mice model. The combination treatment of Cur and Ola also helped in recovering the body weight of tumor-bearing mice. Thus, Cur + Ola combination increased the oral cancer cells death by not only causing the DNA damage but also blocking the induction of BER activity.

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.

Clinical factors associated with prolonged response and survival under olaparib as maintenance therapy in BRCA mutated ovarian cancers

OBJECTIVE

To investigate clinical factors associated with prolonged progression-free survival (PFS) and overall survival (OS) in relapsing epithelial ovarian cancer (EOC) patients with BRCA mutations and receiving olaparib as maintenance therapy in daily practice.

METHODS

Multicenter (8 hospitals) European retrospective study of relapsing EOC patients having germline or somatic mutations of BRCA1/BRCA2 genes and treated with olaparib as maintenance therapy after platinum-based chemotherapy.

RESULTS

One hundred and fifteen patients were included. Median age was 54 years. There were 90 BRCA1 carriers, 24 BRCA2 carriers and one patient had germline mutation of BRCA1 and BRCA2. Six patients had somatic mutations (all BRCA1) and 109 had germline mutations. Ninety percent had serous carcinomas and were platinum-sensitive. Following ultimate platinum-based chemotherapy, 69% of the patients had normalization of CA-125 levels and 87% had RECIST objective responses, either partial (53%) or complete (34%). After a median follow-up of 21 months, median PFS was 12.7 months and median OS was 35.4 months. In multivariate analysis, factors associated with prolonged PFS under olaparib were: platinum-free interval (PFI) ≥ 12 months, RECIST complete response (CR) or partial response (PR) and normalization of CA-125 upon ultimate platinum-based chemotherapy. Factors associated with prolonged OS were PFI ≥ 12 months, CR and normalization of CA-125.

CONCLUSIONS

Platinum-free interval ≥ 12 months, complete response and normalized CA-125 levels after ultimate platinum-based chemotherapy are associated with prolonged PFS and OS in relapsing BRCA1/BRCA2 mutated ovarian cancer patients who received olaparib as maintenance therapy.

Phase I study of continuous olaparib capsule dosing in combination with carboplatin and/or paclitaxel (Part 1)

Background The PARP inhibitor olaparib has shown acceptable toxicity at doses of up to 400 mg twice daily (bid; capsule formulation) with encouraging signs of antitumor activity. Based on its mode of action, olaparib may sensitize tumor cells to DNA-damaging agents. This Phase I trial (NCT00516724) evaluated the safety, pharmacokinetics (PK) and preliminary efficacy of olaparib combined with carboplatin and/or paclitaxel. Methods Patients with advanced solid tumors received olaparib (capsule bid) plus carboplatin (Part A), carboplatin and paclitaxel (Part B), or paclitaxel (Part C). In each part of the study, different drug doses were given to define the most appropriate dose/drug combination to use in further studies. Safety assessments included evaluation of dose-limiting toxicities (DLTs; cycle 1 only), adverse events (AEs) and physical examinations. PK assessments of olaparib, carboplatin and paclitaxel were performed. Tumor responses (RECIST) were assessed every two cycles. Results Fifty-seven patients received treatment. DLTs were reported in two patients (both receiving olaparib 100 mg bid and carboplatin AUC 4; Part A, cohort 2): grade 1 thrombocytopenia with grade 2 neutropenia lasting for 16 days, and grade 2 neutropenia lasting for 7 days. Non-hematologic AEs were predominantly grade 1-2 and included fatigue (70%) and nausea (40%). Bone marrow suppression, mainly neutropenia (51%) and thrombocytopenia (25%), frequently led to dose modifications. Conclusions Olaparib in combination with carboplatin and/or paclitaxel resulted in increased hematologic toxicities, making it challenging to establish a dosing regimen that could be tolerated for multiple cycles without dose modifications.

Phase I study of intermittent olaparib capsule or tablet dosing in combination with carboplatin and paclitaxel (part 2)

Background In the first part of this extensive phase I study (NCT00516724), continuous olaparib twice daily (bid) with carboplatin and/or paclitaxel resulted in myelosuppression and dose modifications. Here, we report the safety, tolerability, and efficacy of intermittent olaparib dosing combined with carboplatin and paclitaxel. Methods Patients with advanced solid tumors (part D) and enriched for ovarian and breast cancer (part E) received olaparib (capsule and tablet formulations) using intermittent schedules (2 to 10 days of a 21-day cycle) combined with carboplatin/paclitaxel. Safety assessments included evaluation of dose-limiting toxicities (DLTs; cycle 1 only), adverse events (AEs), and physical examinations. Pharmacokinetic assessments of olaparib capsule and tablet combined with carboplatin/paclitaxel were performed. Tumor responses (RECIST) were assessed every 2 cycles. Results In total, 132 heavily pre-treated patients were included. One DLT of grade 3 elevated alanine aminotransferase lasting for 8 days was reported (olaparib tablet 100 mg bid days 3-12, carboplatin area under the curve 4 and paclitaxel 175 mg/m²). The most common hematological AEs were neutropenia (47%) and thrombocytopenia (39%), which frequently led to dose modifications. Non-hematological AEs were predominantly grade 1-2, including alopecia (89%) and fatigue (84%). Overall objective response rate was 46%. Conclusions Discontinuous dosing of olaparib resulted in significant myelosuppression leading to dose interruptions and/or delays. Anti-tumor activity was encouraging in patients enriched with BRCA-mutated breast and ovarian cancer. The most appropriate olaparib tablet dose for use in further studies evaluating olaparib in combination with carboplatin and paclitaxel is 50 mg bid (days 1-5).

PARP-1 activity (PAR) determines the sensitivity of cervical cancer to olaparib

OBJECTIVES

Cervical cancer (CC) remains a major health problem worldwide. Poly (adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors (PARPi) have emerged as a promising class of chemotherapeutics in ovarian cancer. We explored the preclinical in vitro and in vivo activity of olaparib against multiple primary whole exome sequenced (WES) CC cells lines and xenografts.

METHODS

Olaparib cell-cycle, apoptosis, homologous-recombination-deficiency (HRD), PARP trapping and cytotoxicity activity was evaluated against 9 primary CC cell lines in vitro. PARP and PAR expression were analyzed by Western blot assays. Finally, olaparib in vivo antitumor activity was tested against CC xenografts.

RESULTS

While none of the cell lines demonstrated HRD, three out of 9 (33.3%) primary CC cell lines showed strong PARylation activity and demonstrated high sensitivity to olaparib in vitro treatment (cutoff IC50 values < 2 μM, p = 0.0012). Olaparib suppressed CC cell growth through cell cycle arrest in the G2/M phase and caused apoptosis (p < 0.0001). Olaparib activity in CC involved both PARP enzyme inhibition and trapping. In vivo, olaparib significantly impaired CC xenografts tumor growth (p = 0.0017) and increased overall animal survival (p = 0.008).

CONCLUSIONS

A subset of CC primary cell lines is highly responsive to olaparib treatment in vitro and in vivo. High level of PARylation correlated with olaparib preclinical activity and may represent a useful biomarker for the identification of CC patients benefitting the most from PARPi.

Study protocols of three parallel phase 1 trials combining radical radiotherapy with the PARP inhibitor olaparib

BACKGROUND

Poly (ADP-ribose) Polymerase (PARP) inhibitors are promising novel radiosensitisers. Pre-clinical models have demonstrated potent and tumour-specific radiosensitisation by PARP inhibitors. Olaparib is a PARP inhibitor with a favourable safety profile in comparison to clinically used radiosensitisers including cisplatin when used as single agent. However, data on safety, tolerability and efficacy of olaparib in combination with radiotherapy are limited.

METHODS

Olaparib is dose escalated in combination with radical (chemo-)radiotherapy regimens for non-small cell lung cancer (NSCLC), breast cancer and head and neck squamous cell carcinoma (HNSCC) in three parallel single institution phase 1 trials. All trials investigate a combination treatment of olaparib and radiotherapy, the NSCLC trial also investigates a triple combination of olaparib, radiotherapy and concurrent low dose cisplatin. The primary objective is to identify the maximum tolerated dose of olaparib in these combination treatments, defined as the dose closest to but not exceeding a 15% probability of dose limiting toxicity. Each trial has a separate dose limiting toxicity definition, taking into account incidence, duration and severity of expected toxicities without olaparib. Dose escalation is performed using a time-to-event continual reassessment method (TITE-CRM). TITE-CRM enables the incorporation of late onset toxicity until one year after treatment in the dose limiting toxicity definition while maintaining an acceptable trial duration. Olaparib treatment starts two days before radiotherapy and continues during weekends until two days after radiotherapy. Olaparib will also be given two weeks and one week before radiotherapy in the breast cancer trial and HNSCC trial respectively to allow for translational research. Toxicity is scored using common terminology criteria for adverse events (CTCAE) version 4.03. Blood samples, and tumour biopsies in the breast cancer trial, are collected for pharmacokinetic and pharmacodynamic analyses.

DISCUSSION

We designed three parallel phase 1 trials to assess the safety and tolerability of the PARP inhibitor olaparib in combination with radical (chemo-)radiotherapy treatment regimens. PARP inhibitors have the potential to improve outcomes in patients treated with radical (chemo-)radiotherapy, by achieving higher locoregional control rates and/or less treatment associated toxicity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT01562210 (registered March 23, 2012), NCT02227082 (retrospectively registered August 27, 2014), NCT02229656 (registered September 1, 2014).

Prexasertib treatment induces homologous recombination deficiency and synergizes with olaparib in triple-negative breast cancer cells

Background

Breast cancer remains as one of the most lethal types of cancer in women. Among various subtypes, triple-negative breast cancer (TNBC) is the most aggressive and hard to treat type of breast cancer. Mechanistically, increased DNA repair and cell cycle checkpoint activation remain as the foremost reasons behind TNBC tumor resistance to chemotherapy and disease recurrence.

Methods

We evaluated the mechanism of prexasertib-induced regulation of homologous recombination (HR) proteins using 20S proteasome inhibitors and RT-PCR. HR efficiency and DNA damages were evaluated using Dr-GFP and comet assays. DNA morphology and DNA repair focus studies were analyzed using immunofluorescence. UALCAN portal was used to evaluate the expression of RAD51 and survival probability based on tumor stage, subtype, and race in breast cancer patients.

Results

Our results show that prexasertib treatment promotes both post-translational and transcriptional mediated regulation of BRCA1 and RAD51 proteins. Additionally, prexasertib-treated TNBC cells revealed over 55% reduction in HR efficiency compared to control cells. Based on these results, we hypothesized that prexasertib treatment induced homologous recombination deficiency (HRD) and thus should synergize with PARP inhibitors (PARPi) in TNBC cells. As predicted, combined treatment of prexasertib and PARPi olaparib increased DNA strand breaks, γH2AX foci, and nuclear disintegration relative to single-agent treatment. Further, the prexasertib and olaparib combination was synergistic in multiple TNBC cell lines, as indicated by combination index (CI) values. Analysis of TCGA data revealed elevated RAD51 expression in breast tumors compared to normal breast tissues, especially in TNBC subtype. Interestingly, there was a discrepancy in RAD51 expression in racial groups, with African-American and Asian breast cancer patients showing elevated RAD51 expression compared to Caucasian breast cancer patients. Consistent with these observations, African-American and Asian TNBC patients show decreased survival.

Conclusions

Based on these data, RAD51 could be a biomarker for aggressive TNBC and for racial disparity in breast cancer. As positive correlation exists between RAD51 and CHEK1 expression in breast cancer, the in vitro preclinical data presented here provides additional mechanistic insights for further evaluation of the rational combination of prexasertib and olaparib for improved outcomes and reduced racial disparity in TNBC.

Patient-reported outcomes in patients with a germline BRCA mutation and HER2-negative metastatic breast cancer receiving olaparib versus chemotherapy in the OlympiAD trial

BACKGROUND

The phase III OlympiAD study (NCT02000622) showed a statistically significant progression-free survival benefit with olaparib versus chemotherapy treatment of physician's choice (TPC) in patients with a germline BRCA mutation and human epidermal growth factor receptor 2-negative metastatic breast cancer. From this study, we report the effect of olaparib on health-related quality of life (HRQoL).

METHODS

Patients were randomised 2:1 to olaparib monotherapy (300 mg twice daily) or single-agent TPC. The primary HRQoL end-point was mean change from baseline in the two-item global health status/QoL score determined from patient-completed European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item module (EORTC QLQ-C30) questionnaires and assessed using a mixed model for repeated measures. Symptoms and functioning domains, best overall response and time to deterioration of QoL were also evaluated.

RESULTS

Overall questionnaire compliance rates were 93.2% for olaparib and 76.3% for TPC. Between-treatment global health status/QoL comparison showed a significant improvement in the olaparib arm versus the TPC arm, with mean change of 3.9 (standard deviation 1.2) versus -3.6 (2.2), a difference of 7.5 points (95% confidence interval [CI]: 2.48, 12.44; P = 0.0035). A higher proportion of patients in the olaparib arm showed a best overall response of 'improvement' in global health status/QoL (33.7% vs 13.4%). Median time to global health status/QoL deterioration was not reached in olaparib patients and was 15.3 months for TPC patients (hazard ratio: 0.44 [95% CI: 0.25, 0.77]; P = 0.004). For EORTC QLQ-C30 symptoms and functioning subscales, only nausea/vomiting symptom score was worse in the olaparib arm than in the TPC arm (across all visits compared with baseline).

CONCLUSION

HRQoL was consistently improved for patients treated with olaparib, compared with chemotherapy TPC.

Efficacy of Novel Bromodomain and Extraterminal Inhibitors in Combination with Chemotherapy for Castration-Resistant Prostate Cancer

BACKGROUND

Chemotherapy is the treatment of choice for metastatic castration-resistant prostate cancer (mCRPC) nonresponsive to androgen receptor-targeted therapies. Nevertheless, the impact of chemotherapy on patient survival is limited and clinical outcome remain dismal. Bromodomain and extraterminal inhibitors (BETis) are attractive therapeutic agents and currently in clinical trials to be tested for their efficacy in prostate cancer patients.

OBJECTIVE

In this study, we evaluated the activity of two clinical stage BETis, INCB054329 and INCB057643, alone and in combination with chemotherapeutics used for the treatment of mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Drug activity was evaluated in vitro by MTT, clonogenic, prostato-sphere, and flow cytometry assays. The activity in vivo was evaluated in mice bearing prostate tumor (22Rv1) xenografts.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cell growth data were analyzed to determine the maximum effect and the concentration that reduces by 50%. For concomitant treatments, the combination index was determined according to the Chou-Talalay method. For in vivo activity, changes in tumor size (T/C_i%), weight (T/C_d%), doubling time, and mouse body weight were monitored. Statistical significance was determined by one-way analysis of variance followed by a Student-Newman-Keuls or Turkey a posteriori test.

RESULTS AND LIMITATIONS

INCB054329 and INCB057643 had significant activity as single agents in human prostate cancer cell lines and 22Rv1 tumor xenografts. Combined treatment with INCB057643 and any of docetaxel, olaparib, or carboplatin was synergistic/additive in vitro. Notably, INCB057643, given with a low-intensity dosing schedule, greatly enhanced the anti-tumor activity of docetaxel, carboplatin, and olaparib in 22Rv1 tumor xenografts.

CONCLUSIONS

Collectively, these results provide the first evidence of the therapeutic benefit obtainable by combining BETis with non-androgen receptor-targeted therapies for the treatment of mCRPC.

PATIENT SUMMARY

Chemotherapy has limited efficacy in patients with metastatic castration-resistant prostate cancer. This study provides evidence of enhanced efficacy of clinically used chemotherapeutics when given in combination with the bromodomain and extraterminal inhibitor INCB057643, expanding the horizon of the current options for the treatment of prostate cancer.

Preparation and Comparison of Oral Bioavailability for Different Nano-formulations of Olaparib

Olaparib (OLA) is a poly ADP ribose polymerase (PARP) inhibitor approved for germline BRCA-mutated (gBRCAm) advanced ovarian cancer and breast cancer. Low oral bioavailability of this drug requires increase in the dose and frequency causing haematological toxicity in the patients. The purpose of this study is to prepare different nano-formulations of OLA lipospheres (LP) by melt dispersion and nano-suspensions (NSP) by solvent evaporation (SE) and wet milling (WM) techniques and compare oral bioavailability of these formulations. Size of the nano-formulations OLA-LP, OLA-NSP_SE and OLA-NSP_WM were found to be 126.71 ± 4.54, 128.6 ± 2.34 and 531.1 ± 5.34 nm with polydispersity index below 0.3. In vitro release studies were performed by dialysis bag method where the sustained drug release was observed from nano-formulations until 9 h with Higuchi for OLA suspended in 2.5% w/v sodium carboxy methyl cellulose (OLA-SP), OLA-LP and OLA-NSP_WM and Peppas for OLA-NSP_SE-based drug release kinetics. In vivo pharmacokinetic studies, haematological toxicity and distribution studies were performed on rats. Results showed that there was an improvement in C_max, AUC_total, t_1/2 and MRT by OLA nano-formulations when compared with OLA-SP. OLA-SP has shown reduction in WBC, platelets and lymphocytes at 12 and 36 h time points; however, no reduction in cell count was observed with OLA nano-formulations. Distribution studies proved FITC nano-formulations were most rapidly absorbed and distributed when compared with FITC-loaded suspension. From the above results, it was concluded that OLA nano-formulations can be an alternative to enhance the oral bioavailability and to reduce the haematological toxicity of OLA.

American Society of Clinical Oncology (ASCO) - 55th Annual Meeting (May 31-June 4, 2019 - Chicago, Illinois, USA)

The theme for this year's meeting of the American Association of Clinical Oncology (ASCO) was 'Caring for Every Patient, Learning from Every Patient'. The meeting consisted of oral, plenary and educational sessions, as well as poster presentations and discussions about important topics in the field of oncology, such as precision medicine, the latest in cancer research impacting patient care, new treatment options and insights for improving access to care. This 55th ASCO annual meeting was held from May 31 to June 4 in Chicago, Illinois, and was attended by over 40,000 cancer experts from around the world who followed a robust program providing opportunities to teach, engage and, most importantly, bring the oncology field together with the aim of improving care for patients with a cancer diagnosis. This report covers some of the later-stage developments and results presented at the meeting.

Olaparib induces browning of in vitro cultures of human primary white adipocytes

Mitochondrial biogenesis is a key feature of energy expenditure and organismal energy balance. Genetic deletion of PARP1 or PARP2 was shown to induce mitochondrial biogenesis and energy expenditure. In line with that, PARP inhibitors were shown to induce energy expenditure in skeletal muscle. We aimed to investigate whether pharmacological inhibition of PARPs induces brown or beige adipocyte differentiation. SVF fraction of human pericardial adipose tissue was isolated and human adipose-derived mesenchymal stem cells (hADMSCs) were differentiated to white and beige adipocytes. A subset of hADMSCs were differentiated to white adipocytes in the presence of Olaparib, a potent PARP inhibitor currently in clinical use, to induce browning. Olaparib induced morphological changes (smaller lipid droplets) in white adipocytes that is a feature of brown/beige adipocytes. Furthermore, Olaparib induced mitochondrial biogenesis in white adipocytes and enhanced UCP1 expression. We showed that Olaparib treatment inhibited nuclear and cytosolic PAR formation, induced NAD⁺/NADH ratio and consequently boosted SIRT1 and AMPK activity and the downstream transcriptional program leading to increases in OXPHOS. Olaparib treatment did not induce the expression of beige adipocyte markers in white adipocytes, suggesting the formation of brown or brown-like adipocytes. PARP1, PARP2 and tankyrases are key players in the formation of white adipose tissue. Hereby, we show that PARP inhibition induces the transdifferentiation of white adipocytes to brown-like adipocytes suggesting that PARP activity could be a determinant of the differentiation of these adipocyte lineages.

Sensitization of chondrosarcoma cells with PARP inhibitor and high-LET radiation

Chondrosarcoma is a malignant tumor that arises from cartilaginous tissue and is radioresistant and chemoresistant to conventional treatments. The preferred treatment consists of surgical resection, which might cause severe disabilities for the patient; in addition, this procedure might be impossible for inoperable locations, such as the skull base. Carbon ion irradiation (hadron therapy) has been proposed as an alternative treatment, primarily due to its greater biological effectiveness and improved ballistic properties compared with conventional radiotherapy with X-rays. The goal of this study was to characterize the genetic mutations of a grade III chondrosarcoma cell line (CH2879) and examine the cellular responses to conventional radiotherapy (X-rays) and hadron therapy (proton and carbon ions) in the presence of the PARP inhibitor Olaparib. To better understand PARP inhibition, we first analyzed the formation of poly-ADP ribose chains by western blot; we observed an increase in its signal after irradiation, which disappeared on addition of the PARP inhibitor. PARPi enhanced ratio of approximately 1.3, 1.8, and 1.5 following irradiation of cells with X-rays, protons, and C-ions, respectively, as detected by clonogenic assay. The decrease in cell survival was confirmed by proliferation assay. The radiosensitivity of CH2879 cells was associated with mutations in homologous recombination repair genes, such as RAD50, SMARCA2 and NBN. This study demonstrates the capacity of the PARP inhibitor Olaparib to radiosensitize mutated chondrosarcoma cells to conventional photon irradiation, proton and carbon ion irradiation.

Combination of PARP inhibitor and temozolomide to suppress chordoma progression

Chordoma, a malignant bone cancer, is highly resistant to conventional therapeutic approaches; this greatly limits radio- and chemotherapeutic options and disease management. In the present study, we investigated three patient-derived chordoma cell lines to elucidate the molecular mechanism of resistance to therapeutics. An in vitro high-throughput chemical screening assay and an in vivo xenograft model were used to identify novel chemosensitizers for chordoma. We found that patient-derived chordoma cell lines recapitulated disease phenotypes, which were highlighted by robust resistance to medical therapy manifested as lack of DNA damage accumulation. Mechanistically, the PARP DNA repair pathway was found to play a central role in this resistance. Chemical screening confirmed that PARP inhibitors could strikingly enhance temozolomide (TMZ) therapy in chordoma cells. Combining the FDA-approved PARP inhibitor, olaparib, with chemotherapeutics not only potentiated DNA damage accumulation, cell cycle arrest, and apoptosis in vitro but also suppressed chordoma xenograft expansion in vivo. We conclude that combining PARP inhibition with TMZ could be an effective therapeutic approach for the clinical management of chordoma. KEY MESSAGES: The PARP DNA repair pathway enhances chemoresistance in chordoma cells. Combining PARP inhibitors with genotoxic agents induces chordoma cell cytotoxicity. PARP inhibitor combining with temozolomide suppresses growth of chordoma in vivo.

MUS81 Inhibition Increases the Sensitivity to Therapy Effect in Epithelial Ovarian Cancer via Regulating CyclinB Pathway

MUS81 is a key endonuclease involved in homologous recombination (HR) repair after DNA double-strand damage. Structure-specific endonucleases (SSEs) plays a crucial role in DNA replication, repair and transcription, and SSEs are also important for maintaining the secondary structure of DNA; therefore, their activity must be precisely controlled to ensure genome stability. We previously described that MUS81 expression was significantly correlated with CyclinB expression based on protein microarray analysis. CyclinB is a cell-cycle regulatory protein that has been shown to be involved in the activation of DNA damage repair checkpoints by inducing G2/M phase arrest, promoting apoptosis, and participating in the regulation of chemotherapeutic drug sensitivity by inducing nuclear degradation, as shown by immunofluorescence assays. In this study, MUS81-downregulated cells were generated using lentivirus-mediated RNAi. Our results demonstrated that the inhibition of MUS81 expression activated the CHK1 and CyclinB signaling pathways and sensitized ovarian cancer cells to X-ray and Olaparib treatment both in vitro and in vivo. MUS81 may be a potential therapeutic target for epithelial ovarian cancer (EOC).

Olaparib and ionizing radiation trigger a cooperative DNA-damage repair response that is impaired by depletion of the VRK1 chromatin kinase

Background

The VRK1 chromatin kinase regulates the organization of locally altered chromatin induced by DNA damage. The combination of ionizing radiation with inhibitors of DNA damage responses increases the accumulation of DNA damage in cancer cells, which facilitates their antitumor effect, a process regulated by VRK1.

Methods

Tumor cell lines with different genetic backgrounds were treated with olaparib to determine their effect on the activation of DNA repair pathways induced by ionizing radiation. The effect of combining olaparib with depletion of the chromatin kinase VRK1 was studied in the context of double-strand breaks repair pathway after treatment with ionizing radiation. The initiation and progression of DDR were studied by specific histone acetylation, as a marker of local chromatin relaxation, and formation of γH2AX and 53BP1 foci.

Results

In this work, we have studied the effect that VRK1 by itself or in collaboration with olaparib, an inhibitor of PARP, has on the DNA oxidative damage induced by irradiation in order to identify its potential as a new drug target. The combination of olaparib and ionizing radiation increases DNA damage permitting a significant reduction of their respective doses to achieve a similar amount of DNA damage detected by γH2AX and 53BP1 foci. Different treatment combinations of olaparib and ionizing radiation permitted to reach the maximum level of DNA damage at lower doses of both treatments. Furthermore, we have studied the effect that depletion of the VRK1 chromatin kinase, a regulator of DDR, has on this response. VRK1 knockdown impaired all steps in the DDR induced by these treatments, which were detected by a reduction of sequential markers such as H4K16 ac, γH2AX, NBS1 and 53BP1. Moreover, this effect of VRK1 is independent of TP53 or ATM, two genes frequently mutated in cancer.

Conclusion

The protective DNA damage response induced by ionizing radiation is impaired by the combination of olaparib with depletion of VRK1, and can be used to reduce doses of radiation and their associated toxicity. Proteins implicated in DNA damage responses are suitable targets for development of new therapeutic strategies and their combination can be an alternative form of synthetic lethality.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1204-1) contains supplementary material, which is available to authorized users.

Pharmacokinetics and safety of olaparib tablets as monotherapy and in combination with paclitaxel: results of a Phase I study in Chinese patients with advanced solid tumours

PURPOSE

Chinese patients have been enrolled in multiple Phase III trials of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib (Lynparza); however, the pharmacokinetic (PK) profile of olaparib has not been investigated in this population. This two-part, open-label Phase I study was, therefore, carried out to determine the PK and safety profile of olaparib (tablet formulation) in Chinese patients with advanced solid tumours as monotherapy and in combination with paclitaxel (NCT02430311).

METHODS

The PK profile of olaparib 300 mg (twice daily [bid]; Cohort 1) as monotherapy after a single dose and at steady state, and 100 mg (bid; Cohort 2) as monotherapy (single dose and at steady state) and in combination (at steady state) with weekly paclitaxel (80 mg/m²) was assessed during Part A. Patients could continue to receive treatment (monotherapy, Cohort 1; combination therapy, Cohort 2) in Part B, which assessed safety and tolerability.

RESULTS

Twenty and 16 patients were enrolled into Cohorts 1 and 2, respectively. Steady-state olaparib exposure increased slightly less than proportionally with increasing monotherapy dose and inter-patient variability was high. A statistically significant decrease in olaparib exposure was seen when given in combination with paclitaxel. Discontinuation due to adverse events (AEs) was rare and haematological AEs were more common in patients receiving combination treatment.

CONCLUSIONS

The PK and safety profile of olaparib monotherapy in Chinese patients is consistent with that seen previously in Western and Japanese patients, and the recommended Phase III monotherapy tablet dose (300 mg bid) is suitable for use in this population.

Quantitative Characterization of Olaparib in Nanodelivery System and Target Cell Compartments by LC-MS/MS

Olaparib, an orally active inhibitor of poly(ADP-ribose)polymerase(PARP), is the drug of choice in the treatment of gBRCA1/2+ metastatic breast cancers. Unfortunately, Olaparib is poorly soluble with low bioavailability and tumor accumulation; nano-delivery could be a good choice to overcome these disadvantages. Here, a rapid and robust HPLC-ESI–MS/MS method for the quantification of Olaparib in ferritin nano-carriers led to the development of cells compartments, different tissues, plasma and urines and were validated to assess the effects of nano-delivery on cell compartment distribution of the drug. This method allows the quantification of Olaparib within the linear range of 0.1–10ng/mL in cells culture medium and cell cytoplasm, of 0.5–10ng/mL in nuclei, of 0.5–100ng/mL in plasma and urine and of 10–500ng/mL in tissue samples (kidney and liver). The limit of quantification was found to be 1.54 ng/mL for liver, 2.87 ng/mL for kidney, and lower than 0.48 ng/mL for all matrices. The method has been applied to quantify Ola encapsulated in ferritin-nano-carriers during the nano-drug development. The application of the method to human BRCA-mutated cell model to quantify the Olaparib distribution after incubation of free or ferritin-encapsulated Olaparib is also reported. This sensitive method allows the quantification of low concentrations of Olaparib released from nano-carriers in different cell compartments, leading to the determination of the drug release and kinetic profile of an essential parameter to validate nano-carriers.

Differential Response to Olaparib Treatment Among Men with Metastatic Castration-resistant Prostate Cancer Harboring BRCA1 or BRCA2 Versus ATM Mutations

BACKGROUND

Poly ADP-ribose polymerase (PARP) inhibitors, such as olaparib, are being explored as a treatment option for metastatic castration-resistant prostate cancer (mCRPC) in men harboring mutations in homologous recombination DNA-repair genes. Whether responses to PARP inhibitors differ according to the affected gene is currently unknown.

OBJECTIVE

To determine whether responses to PARP inhibitors differ between men with BRCA1/2 and those with ATM mutations.

DESIGN, SETTING, AND PARTICIPANTS

This was a multicenter retrospective review of 23 consecutive men with mCRPC and pathogenic germline and/or somatic BRCA1/2 or ATM mutations treated with olaparib at three academic sites in the USA.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The proportion of patients achieving a ≥50% decline in prostate-specific antigen (PSA₅₀ response) was compared using Fisher's exact test. Clinical and radiographic progression-free survival (PFS) and overall survival were estimated using Kaplan-Meier analyses and compared using the log-rank test.

RESULTS AND LIMITATIONS

The study included two men with BRCA1 mutations, 15 with BRCA2 mutations, and six with ATM mutations. PSA₅₀ responses to olaparib were achieved in 76% (13/17) of men with BRCA1/2 versus 0% (0/6) of men with ATM mutations (Fisher's exact test; p=0.002). Patients with BRCA1/2 mutations had median PFS of 12.3mo versus 2.4mo for those with ATM mutations (hazard ratio 0.17, 95% confidence interval 0.05-0.57; p=0.004). Limitations include the retrospective design and relatively small sample size.

CONCLUSIONS

Men with mCRPC harboring ATM mutations experienced inferior outcomes to PARP inhibitor therapy compared to those harboring BRCA1/2 mutations. Alternative therapies should be explored for patients with ATM mutations.

PATIENT SUMMARY

Mutations in BRCA1/2 and ATM genes are common in metastatic prostate cancer. In this study we compared outcomes for men with BRCA1/2 mutations to those for men with ATM mutations being treated with olaparib. We found that men with ATM mutations do not respond as well as men with BRCA1/2 mutations.

SPAG5 upregulation contributes to enhanced c-MYC transcriptional activity via interaction with c-MYC binding protein in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that lacks effective therapeutic targets. Sperm-associated antigen 5 (SPAG5) is a mitotic spindle-associated protein that is involved in various biological processes in cervical cancer and bladder urothelial carcinoma. However, the role of SPAG5 in TNBC remains undefined.

METHODS

The expression of SPAG5 was examined in TNBC patients via quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry (IHC). The biological functions of SPAG5 in TNBC and the underlying mechanisms were investigated in vitro and in vivo.

RESULTS

SPAG5 expression was significantly upregulated in TNBC tissues compared with that in paired adjacent noncancerous tissues (ANTs). High SPAG5 expression was associated with increased lymph node metastasis and high risk of local recurrence. SPAG5 protein expression was significantly associated with poor disease-free survival in TNBC. Gene set enrichment analysis of TNBC data from The Cancer Genome Atlas (TCGA) indicated that high SPAG5 expression was significantly associated with cell cycle and the ATR-BRCA pathway. Functional assays demonstrated that SPAG5 expression promoted tumor growth in vitro and in vivo. In addition, SPAG5-silenced cells were more sensitive to the PARP inhibitor (PARPi) olaparib. Mechanistically, SPAG5 interacted with c-MYC binding protein (MYCBP), thereby increasing MYCBP protein levels and leading to increased c-MYC transcriptional activity, which promoted the expression of the c-MYC target genes: CDC20, CDC25C, BRCA1, BRCA2, and RAD51.Knockdown of MYCBP or c-MYC abolished the SPAG5-induced cell-cycle progression and cell proliferation of TNBC.

CONCLUSIONS

Collectively, our results indict that SPAG5 is an efficient prognostic factor in TNBC, and that SPAG5 knockdown increases the sensitivity of TNBC to the PARPi olaparib. SPAG5 promotes tumor growth and DNA repair by increasing c-MYC transcriptional activity via interaction with MYCBP. The SPAG5/MYCBP/c-MYC axis may represent a potential therapeutic target for TNBC treatment.

Gene expression profiling of homologous recombination repair pathway indicates susceptibility for olaparib treatment in malignant pleural mesothelioma in vitro

BACKGROUND

Malignant pleural mesothelioma (MPM) is a tumour arising from pleural cavities with poor prognosis. Multimodality treatment with pemetrexed combined with cisplatin shows unsatisfying response-rates of 40%. The reasons for the rather poor efficacy of chemotherapeutic treatment are largely unknown. However, it is conceivable that DNA repair mechanisms lead to an impaired therapy response. We hypothesize a major role of homologous recombination (HR) for genome stability and survival of this tumour. Therefore, we analysed genes compiled under the term "BRCAness". An inhibition of this pathway with olaparib might abrogate this effect and induce apoptosis.

METHODS

We investigated the response of three MPM cell lines and lung fibroblasts serving as a control to treatment with pemetrexed, cisplatin and olaparib. Furthermore, we aimed to find possible correlations between response and gene expression patterns associated with BRCAness phenotype. Therefore, 91 clinical MPM samples were digitally screened for gene expression patterns of HR members.

RESULTS

A BRCAness-dependent increase of apoptosis and senescence during olaparib-based treatment of BRCA-associated-protein 1 (BAP1)-mutated cell lines was observed. The gene expression pattern identified could be found in approx. 10% of patient samples. Against this background, patients could be grouped according to their defects in the HR system. Gene expression levels of Aurora Kinase A (AURKA), RAD50 as well as DNA damage-binding protein 2 (DDB2) could be identified as prognostic markers in MPM.

CONCLUSIONS

Defects in HR compiled under the term BRCAness are a common event in MPM. The present data can lead to a better understanding of the underlaying cellular mechanisms and leave the door wide open for new therapeutic approaches for this severe disease with infaust prognosis. Response to Poly (ADP-ribose)-Polymerase (PARP)-Inhibition could be demonstrated in the BAP1-mutated NCI-H2452 cells, especially when combined with cisplatin. Thus, this combination therapy might be effective for up to 2/3 of patients, promising to enhance patients' clinical management and outcome.

Current strategies for the targeted treatment of high-grade serous epithelial ovarian cancer and relevance of BRCA mutational status

Epithelial ovarian cancer is the most lethal gynecologic malignancy. In most women, it is diagnosed at an advanced stage, which largely explains the poor prognosis of this malignancy. Germline mutations of the genes BRCA1 and BRCA2, which encode proteins essential for the repair of double-strand DNA breaks through homologous recombination, lead to increased cancer predisposition. BRCA mutations are present in approximately 14% of epithelial ovarian cancers. Somatic BRCA mutations have also been described. Current first-line treatment of high-grade epithelial ovarian cancer includes debulking surgery followed by combination chemotherapy, usually carboplatin and paclitaxel. Ovarian cancer is highly sensitive to chemotherapy, in particular to platinum drugs. Most patient will achieve remission with initial chemotherapy, but most will eventually experience disease recurrence. Targeted therapies, including the anti-angiogenic agent bevacizumab and oral poly (ADP-ribose) polymerase (PARP) inhibitors, have been recently approved for the treatment of ovarian cancer, based on the results from randomized clinical trials showing significant benefits in terms of progression-free survival, with acceptable tolerability and no detrimental effects on quality of life. Olaparib, the first PARP inhibitor to be granted approval, is currently indicated as maintenance monotherapy in ovarian cancer patients with relapsed disease and mutated BRCA who have achieved a complete or partial response to platinum-based chemotherapy. The analysis of BRCA mutational status has, therefore, also become crucial for therapeutic decisions. Such advances are making personalized treatment of ovarian cancer feasible. Here we briefly review treatments for platinum-sensitive, high-grade serous epithelial ovarian cancer that are currently available in Italy, with a focus on targeted therapies and the relevance of BRCA mutational analysis. Based on the evidence and on current guidelines, we propose strategies for the tailored treatment of patients with relapsed ovarian cancer that take into account BRCA mutational status and the treatment received in the first-line setting.

Phase I clinical study of oral olaparib in pediatric patients with refractory solid tumors: study protocol

Background

There is no established standard chemotherapy for recurrent pediatric solid tumors such as neuroblastoma and sarcoma. Since some of these tumor cells show dysfunctions in homologous recombination repair, the goal is to conduct a phase I study of olaparib, a poly(ADP-ribose) polymerase inhibitor. In this clinical trial, the aims are to evaluate the safety, tolerability, and efficacy of olaparib in pediatric patients with refractory solid tumors and to recommend a dose for phase II trials.

Methods

In this open-label, multicenter study, olaparib tablets (62.5, 125, and 187.5 mg/m² b.i.d.) will be administered orally in a standard 3 + 3 dose escalation design. Patients aged 3 to 18 years with recurrent pediatric solid tumors are eligible. Pharmacokinetic and pharmacodynamic analyses will also be performed.

Discussion

This study aims to extend the indications for olaparib by assessing its safety and efficacy in pediatric refractory solid tumor patients.

Trial registration

UMIN-CTR (UMIN000025521); Registered on January 4, 2017.

PARP inhibitors affect growth, survival and radiation susceptibility of human alveolar and embryonal rhabdomyosarcoma cell lines

PURPOSE

PARP inhibitors (PARPi) are used in a wide range of human solid tumours but a limited evidence is reported in rhabdomyosarcoma (RMS), the most frequent childhood soft-tissue sarcoma. The cellular and molecular effects of Olaparib, a specific PARP1/2 inhibitor, and AZD2461, a newly synthesized PARP1/2/3 inhibitor, were assessed in alveolar and embryonal RMS cells both as single-agent and in combination with ionizing radiation (IR).

METHODS

Cell viability was monitored by trypan blue exclusion dye assays. Cell cycle progression and apoptosis were measured by flow cytometry, and alterations of specific molecular markers were investigated by, Real Time PCR, Western blotting and immunofluorescence experiments. Irradiations were carried out at a dose rate of 2 Gy (190 UM/min) or 4 Gy (380 UM/min). Radiosensitivity was assessed by using clonogenic assays.

RESULTS

Olaparib and AZD2461 dose-dependently reduced growth of both RH30 and RD cells by arresting growth at G2/M phase and by modulating the expression, activation and subcellular localization of specific cell cycle regulators. Downregulation of phospho-AKT levels and accumulation of γH2AX, a specific marker of DNA damage, were significantly and persistently induced by Olaparib and AZD2461 exposure, this leading to apoptosis-related cell death. Both PARPi significantly enhanced the effects of IR by accumulating DNA damage, increasing G2 arrest and drastically reducing the clonogenic capacity of RMS-cotreated cells.

CONCLUSIONS

This study suggests that the combined exposure to PARPi and IR might display a role in the treatment of RMS tumours compared with single-agent exposure, since stronger cytotoxic effects are induced, and compensatory survival mechanisms are prevented.

Effect of AR antagonist combined with PARP1 inhibitor on sporadic triple-negative breast cancer bearing AR expression and methylation-mediated BRCA1 dysfunction

Triple-negative breast cancer (TNBC) patients usually present worse clinical outcomes due to their high heterogeneity. The purpose of our study is to investigate the prognostic role of AR and BRCA1 expression in sporadic TNBC patients, and effect of AR blockade and PARP1 inhibitor for TNBC patients who characterized by positive-AR expression and BRCA1 inactivation or dysfunction. In our present study, we found that AR is expressed in 43.6% and 34.0% of TNBC tissues, when 1% or 10% staining was used as the threshold for AR positivity, respectively. When 1% staining was used as the threshold, AR expression indicates a poor disease-free survival (DFS) of TNBC patients. TNBC patients with negative BRCA1 show a poor DFS, and BRCA1 suppression is associated with the methylation status of its promoter. Interestingly, BRCA1-/AR + TNBC patients have shorter DFS than other TNBC patients regardless of the threshold for AR positivity. AR antagonists MDV3100 enhances the PARP1 inhibitor Olaparib-mediated decrease of cell viability in AR-positive/BRCA1-inactivated cells in vitro and in vivo. Our results suggested that combination of AR blockade and PARP1 inhibitor may be a potential strategy for sporadic TNBC patients who characterized by positive-AR expression and BRCA1 inactivation or dysfunction.

Synthesis, preliminarily biological evaluation and molecular docking study of new Olaparib analogues as multifunctional PARP-1 and cholinesterase inhibitors

A series of new Olaparib derivatives was designed and synthesized, and their inhibitory activities against poly (ADP-ribose) polymerases-1 (PARP-1) enzyme and cancer cell line MDA-MB-436 in vitro were evaluated. The results showed that compound 5l exhibited the most potent inhibitory effects on PARP-1 enzyme (16.10 ± 1.25 nM) and MDA-MB-436 cancer cell (11.62 ± 2.15 μM), which was close to that of Olaparib. As a PARP-1 inhibitor had been reported to be viable to neuroprotection, in order to search for new multitarget-directed ligands (MTDLs) for the treatment of Alzheimer’s disease (AD), the inhibitory activities of the synthesized compounds against the enzymes AChE (from electric eel) and BChE (from equine serum) were also tested. Compound 5l displayed moderate BChE inhibitory activity (9.16 ± 0.91 μM) which was stronger than neostigmine (12.01 ± 0.45 μM) and exhibited selectivity for BChE over AChE to some degree. Molecular docking studies indicated that 5l could bind simultaneously to the catalytic active of PARP-1, but it could not interact well with huBChE. For pursuit of PARP-1 and BChE dual-targeted inhibitors against AD, small and flexible non-polar groups introduced to the compound seemed to be conducive to improving its inhibitory potency on huBChE, while keeping phthalazine-1-one moiety unchanged which was mainly responsible for PARP-1 inhibitory activity. Our research gave a clue to search for new agents based on AChE and PARP-1 dual-inhibited activities to treat Alzheimer’s disease.

The Drug Combination of SB202190 and SP600125 Significantly Inhibit the Growth and Metastasis of Olaparib-resistant Ovarian Cancer Cell

BACKGROUND & OBJECTIVE

Many targeted ovarian cancer patients are resistant to olaparib treatment. Here we seek to understand the underlying molecular events and search for potential combinational therapeutics to surmount the intrinsic olaparib resistance in human ovarian cancer.

METHODS

The cytotoxicity was determined by the MTT assay and cell viability was measured using Cell Counting Kit-8 (CCK-8). Protein expressions of ERK, P38, JNK, ERK5, LC3, N-CADHERIN, α-SMA were determined by western blotting. The invasion capacity was evaluated by the transwell chamber. Autophagy flux was monitored by the LC3 puncta formation. The epithelial-mesenchymal transition (EMT) markers were profiled by immunoblotting detection. The in vivo tumor progression was determined by xenograft mice model.

RESULTS

The olaparib-resistant cell lines were successfully generated in both SKOV3 and A2780 cells. The proliferative index was significantly higher in resistant cells in comparison with sensitive counterparts in the presence of olaparib. Both P38 and JNK were up-regulated in olaparib-resistant cells. The combinational treatment with P38-specific inhibitor SB202190 and JUN-specific inhibitor SP600125 significantly suppressed cell growth and migration, which was further attributed to the induction of autophagy flux and inhibition of EMT processing. We further consolidated the anti-tumor activities of SB202190 and SP600125 in xenograft mice.

CONCLUSION

Our data suggested that aberrant over-expression of P38 and JNK is causally linked to the olaparib resistance in ovarian cancer. Combination of P38 and JUN inhibitors demonstrated significant anti-tumor activity both in vitro and in vivo. Our study highlighted the potential therapeutic value of Mitogen-Activated Protein Kinase (MAPK) inhibitors in olaparib-resistant human ovarian cancer.

Activity of durvalumab plus olaparib in metastatic castration-resistant prostate cancer in men with and without DNA damage repair mutations

Background

Checkpoint inhibitors have not been effective for prostate cancer as single agents. Durvalumab is a human IgG1-K monoclonal antibody that targets programmed death ligand 1 and is approved by the U.S. Food and Drug Administration for locally advanced or metastatic urothelial cancer and locally advanced, unresectable stage 3 non-small cell lung cancer. Olaparib, a poly (ADP-ribose) polymerase inhibitor, has demonstrated an improvement in median progression-free survival (PFS) in select patients with metastatic castration-resistant prostate cancer (mCRPC). Data from other trials suggest there may be improved activity in men with DNA damage repair (DDR) mutations treated with checkpoint inhibitors. This trial evaluated durvalumab and olaparib in patients with mCRPC with and without somatic or germline DDR mutations.

Methods

Eligible patients had received prior enzalutamide and/or abiraterone. Patients received durvalumab 1500 mg i.v. every 28 days and olaparib 300 mg tablets p.o. every 12 h until disease progression or unacceptable toxicity. All patients had biopsies of metastatic lesions with an evaluation for both germline and somatic mutations.

Results

Seventeen patients received durvalumab and olaparib. Nausea was the only nonhematologic grade 3 or 4 toxicity occurring in > 1 patient (2/17). No patients were taken off trial for toxicity. Median radiographic progression-free survival (rPFS) for all patients is 16.1 months (95% CI: 4.5–16.1 months) with a 12-month rPFS of 51.5% (95% CI: 25.7–72.3%). Activity is seen in patients with alterations in DDR genes, with a median rPFS of 16.1 months (95% CI: 7.8–18.1 months). Nine of 17 (53%) patients had a radiographic and/or PSA response. Patients with fewer peripheral myeloid-derived suppressor cells and with alterations in DDR genes were more likely to respond. Early changes in circulating tumor cell counts and in both innate and adaptive immune characteristics were associated with response.

Conclusions

Durvalumab plus olaparib has acceptable toxicity, and the combination demonstrates efficacy, particularly in men with DDR abnormalities.

Trial registration

ClinicalTrials.gov identifier: NCT02484404.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0463-2) contains supplementary material, which is available to authorized users.

Intraperitoneal delivery of NanoOlaparib for disseminated late-stage cancer treatment

Background

PARP inhibitors, such as Olaparib, have advanced the treatment of ovarian cancer by providing patients with an effective and molecularly-targeted maintenance therapy. However, all orally-administered drugs, including Olaparib, must undergo first-pass metabolism. In contrast, a nanoparticle delivery system has the advantage of administering Olaparib directly into the peritoneal cavity for local treatment. Consequently, we sought to optimize the sustained-release formulation NanoOlaparib, previously deemed effective as an intravenous solid tumor treatment, for the local treatment of disseminated disease via intraperitoneal (i.p.) therapy.

Methods

The tumor cell line 404, which was derived from a Brca2^−/−, Tp53^−/−, Pten^−/− genetically engineered mouse model, exhibited high sensitivity to Olaparib in vitro. It was chosen for use in developing an i.p. spread xenograft for testing nanotherapy efficacy in vivo. NanoOlaparib as a monotherapy or in combination with cisplatin was compared to oral Olaparib alone or in combination using two different dose schedules. A pilot biodistribution study was performed to determine drug accumulation in various organs following i.p. administration.

Results

Daily administration of NanoOlaparib reduced tumor growth and decreased the variability of the treatment response observed with daily oral Olaparib administration. However, systemic toxicity was observed in both the NanoOlaparib and vehicle (empty nanoparticle) treated groups. Scaling back the administration to twice weekly was well tolerated up to 100 mg/kg but reduced the effect on tumor growth. Biodistribution profiles indicated that NanoOlaparib began accumulating in tissues within an hour of administration and persisted for at least 72 hours after a single dose, exiting the peritoneal cavity faster than expected.

Conclusion

NanoOlaparib must be modified for use against disseminated disease. Future avenues to develop NanoOlaparib as an i.p. therapy include a modified surface-coating to retain it in the peritoneal cavity and prevent entry into systemic circulation, in addition to targeting moieties for localization in tumor cells.

Olaparib induced senescence under P16 or P53 dependent manner in ovarian cancer

Objective

Poly (ADP-ribose) polymerase (PARP) is an important molecule in the early stress response of DNA damage, which is involved in DNA damage repair and cellular senescence. Olaparib, as PARP inhibitor, has an anti-tumor effect on high grade serous ovarian cancer, but its effects on cellular senescence have not been reported. This study intends to explore the role of olaparib in the regulation of senescence in ovarian cancer cells.

Methods

The effects of olaparib on the senescence of ovarian cancer cells were detected by using the senescence-associated β-galactosidase (SA-β-Gal) and senescence-associated heterochromatin aggregation (SAHF). Quantitative real-time polymerase chain reaction was used to analyze the senescence-associated secretory phenotype (SASP). Cell cycle and apoptosis were detected by flow cytometry. The effect of olaparib on tumor growth was analyzed in a nude mouse xenograft transplantation model.

Results

Long-term (6 days) treatment with olaparib (5 μM) significantly inhibited the growth of ovarian cancer cells, leading to arrest the cell cycle at G0/G1 phase, significant increase the number of positive SA-β-Gal stained cells and positive SAHF cells. The expression of P16 and retinoblastoma protein (p-RB) were significantly enhanced in SKOV3 cells under olaparib treated, meanwhile, the expression of P53 and p-RB were upregulated in A2780 cells. In OVCAR-3 cells, the expression of P53 was downregulated and p-RB was upregulated. Mice with SKOV3 xenograft transplantation was given olaparib (10 mg/kg/day) via abdominal cavity administration, the tumor volume was reduced (p<0.01).

Conclusion

Continuous low dosage administration of olaparib induced senescence under P16 or P53 dependent manner in ovarian cancer.

PARP inhibitor re‑sensitizes Adriamycin resistant leukemia cells through DNA damage and apoptosis

Resistance to Adriamycin (ADR) is an increasing problem in the treatment of leukemia and the development of novel therapeutic strategies is becoming increasingly important. Olaparib is a poly (adenosine diphosphate-ribose) polymerase (PARP) 1 inhibitor, which has promising antitumor activity in patients with metastatic breast cancer and germline BRCA mutations. Previously published studies have indicated that Olaparib is able to overcome drug resistance in cancer; however, its underlying mechanism of action is yet to be elucidated. The aim of the present study was to explore the mechanism underlying re-sensitization. Annexin V-propidium iodide staining indicated that the percentage of apoptotic ADR resistant cells was markedly increased and the cell cycle was blocked at the G2/M-phase following treatment with ADR combined with Olaparib, when compared with the control group. The alkaline comet assay demonstrated that ADR combined with Olaparib significantly upregulated the induction of the DNA damage response in ADR-resistant cells. Western blot analysis revealed that the protein expression of γ-H2A histone family member X, cleaved PARP, caspase 3 and cleaved caspase 3 was markedly enhanced, while the cell cycle-associated protein cyclin B1 was downregulated in K562/ADR cells following treatment with a combination of ADR and Olaparib. Similar synergistic cytotoxicity was observed in blood mononuclear cells, which were isolated from patients with chemotherapy-resistant leukemia. As Olaparib is available for clinical use, the results of the present study provide a rationale for the development of Olaparib combinational therapies for cases of ADR resistant leukemia.

Cyclin D1 silencing impairs DNA double strand break repair, sensitizes BRCA1 wildtype ovarian cancer cells to olaparib

OBJECTIVE

Poly(ADP-ribose) polymerase inhibitors (PARPi) are active in cancer cells that have impaired repair of DNA by the homologous recombination (HR) pathway. Strategies that disrupt HR may sensitize HR-proficient tumors to PARP inhibition. As a component of the core cell cycle machinery, cyclin D1 has unexpected function in DNA repair, suggesting that targeting cyclin D1 may represent a plausible strategy for expanding the utility of PARPi in ovarian cancer.

METHODS

BRCA1 wildtype ovarian cancer cells (A2780 and SKOV3) were treated with a combination of CCND1 siRNA and olaparib in vitro. Cell viability was assessed by MTT. The effects of the combined treatment on DNA damage repair and cell cycle progression were examined to dissect molecular mechanisms. In vivo studies were performed in an orthotopic ovarian cancer mouse model. Animals were treated with a combination of lentivirus-mediated CCND1 shRNA and olaparib or olaparib plus scrambled shRNA. Molecular downstream effects were examined by immunohistochemistry.

RESULTS

Silencing of cyclin D1 sensitized ovarian cancer cells to olaparib through interfering with RAD51 accumulation and inducing cell cycle G0/G1 arrest. Treatment of lentivirus-mediated CCND1-shRNA in nude mice statistically significantly augmented the olaparib response (mean tumor weight ± SD, CCND1-shRNA plus olaparib vs scrambled shRNA plus olaparib: 0.172 ± 0.070 g vs 0.324 ± 0.044 g, P< 0.05).

CONCLUSIONS

Silencing of cyclin D1 combined with olaparib may lead to substantial benefit for ovarian cancer management by mimicking a BRCAness phenotype, and induction of G0/G1 cell cycle arrest.

Pharmacokinetic Effects and Safety of Olaparib Administered with Endocrine Therapy: A Phase I Study in Patients with Advanced Solid Tumours

INTRODUCTION

The PARP inhibitor olaparib is efficacious as monotherapy and has potential application in combination with endocrine therapy for the treatment of breast cancer. This phase I study assessed the safety and pharmacokinetic (PK) profiles of olaparib combined with tamoxifen, anastrozole or letrozole in patients with advanced solid tumours.

METHODS

During part A, PK profiles were assessed in three consecutive treatment periods: (1) olaparib (tablet) 300 mg bid, days 1-5 followed by a 4-day washout; (2) cohort 1, tamoxifen 60 mg loading dose qd days 10-13, 20 mg qd days 14-26; cohort 2, anastrozole 1 mg qd days 10-19; cohort 3, letrozole 2.5 mg qd days 10-38; (3) as for period 2, with concomitant olaparib 300 mg bid for 5 days. Patients could then enter part B and receive olaparib monotherapy (300 mg bid continuously). Safety was assessed in parts A and B until 12 months after the last patient entered part B.

RESULTS

Seventy-nine patients (20.3% with breast cancer) received treatment in part A; 72 completed part A and 69 entered part B. Anastrozole and letrozole had no effect on the PK profile of olaparib and vice versa. Co-administration with tamoxifen produced a modest decrease in exposure to olaparib [geometric least-squares mean (GLSmean) C_max,ss and AUC_0-τ decreased by 20% (90% CI 0.71-0.90) and 27% (0.63-0.84), respectively]. Exposure to tamoxifen was slightly increased when combined with olaparib [GLSmean C_max,ss and AUC_0-τ increased by 13% (1.06-1.22) and 16% (1.11-1.21), respectively]; however, the 90% CI fell within the 0.7-1.43 boundary and there were no changes in exposure to tamoxifen metabolites. The safety profile for olaparib alone and in combination with the antihormonal therapies was acceptable.

CONCLUSIONS

The combination of olaparib and either anastrozole, letrozole or tamoxifen was generally well tolerated, with no clinically relevant PK interactions identified.

FUNDING

AstraZeneca.

CLINICAL TRIAL REGISTRATION

NCT02093351.

Response to olaparib in metastatic castration-resistant prostate cancer with germline BRCA2 mutation: a case report

Background

Prostate cancer is a heterogeneous disease, meaning patients would benefit from different treatment strategies based on their molecular stratification. In recent years, several genomic studies have identified prostate cancers with defects in DNA repair genes. It is known that the PARP inhibitor, olaparib, has a significant synthetic lethal effect on tumors with BRCA 1/2 mutations, particularly in ovarian and breast cancer.

Case presentation

In this study, we describe a patient with metastatic castration-resistant prostate cancer (mCRPC) containing a BRCA2 germline mutation who underwent olaparib treatment. The efficacy of the treatment was monitored by serum TPSA level as well as mutation levels of circulating tumor DNA (ctDNA) using next-generation sequencing (NGS). The patient responded to the olaparib treatment as indicated by the minimal residual levels of TPSA and tumor-specific mutations of ctDNA in plasma after four months of treatment, although the patient eventually progressed at six-month post-treatment with significantly elevated and newly acquired somatic mutations in ctDNA.

Conclusions

Our study provides evidence that mCRPC with BRCA2 germline mutations could response to PARP inhibitor, which improves patient’s outcome. We further demonstrated that NGS-based genetic testing on liquid biopsy can be used to dynamically monitor the efficacy of treatment.

PARP3 inhibitors ME0328 and olaparib potentiate vinorelbine sensitization in breast cancer cell lines

PURPOSE

PARP-3 is member of the PARP family of poly (ADP-ribose) polymerases involved in ADPribosylation. PARPs are involved in the basic mechanisms of DNA repair. PARP3, a critical player for efficient mitotic progression, is required for the stabilization of the mitotic spindle by regulation of the mitotic components, NuMA and Tankyrase 1.

METHODS

The sensitization effect of vinorelbine on PARP3 inhibition-induced cytotoxicity was assessed by the SRB assay. The contribution of programed cell death and cell cycle arrest to the sensitization effect were determined by assessing changes in Annexin V, a marker of apoptosis. Alterations in cell cycle progression were assessed by cell cycle analysis. We used immunofluorescence to assess the effect of vinorelbine and/or PARP3 inhibitors on tubulin and microtubule depolarization. The PARP3 chemiluminescent assay kit was used for PARP3 activity.

RESULTS

PARP3 inhibitors sensitize breast cancer cells to vinorelbine, a vinca alkaloid used in the treatment of metastatic breast cancer. Olaparib which was originally described as a PARP1 and 2 inhibitor has recently been shown to be a potent PARP3 inhibitor while ME0328 is a more selective PARP3 inhibitor. The combination of vinorelbine with nontoxic concentrations of ME0328 or olaparib reduces vinorelbine resistance by 10 and 17 fold, respectively, potentiating vinorelbine-induced arrest at the G2/M boundary. In addition, PARP3 inhibition potentiates vinorelbine interaction with tubulin. Furthermore, olaparib or ME0328 potentiates vinorelbine-induced PARP3 inhibition, mitotic arrest, and apoptosis.

CONCLUSION

Our results indicated this approach with PARP3 inhibitors and vinorelbine is unique and promising for breast cancer patients with metastases. This combination could significantly increase the survival of breast cancer patients with metastases.

The PARP inhibitor olaparib potentiates the effect of the DNA damaging agent doxorubicin in osteosarcoma

Background

PARP1 facilitates the recovery of DNA-damaged cells by recruiting DNA damage response molecules such as γH2AX and BRCA1/2, and plays a role in resistance to antitumor therapies. Therefore, PARP inhibition being evaluated as an anti-cancer therapy. However, there are limited studies regrading PARP inhibition in osteosarcoma.

Methods

We evaluated the expression of DNA damage response molecules in 35 human osteosarcomas and investigated the effects of co-treatment of the PARP inhibitor, olaparib, and doxorubicin in osteosarcoma cells.

Results

The expression patterns of PARP1, γH2AX, BRCA1, and BRCA2 were significantly associated with shorter survival of osteosarcoma patients. In osteosarcoma cells, knock-down of PARP1 and treatment of olaparib significantly inhibited proliferation of cells and induced apoptosis. Moreover, the anti-tumor effect was more significant with co-treatment of olaparib and doxorubicin in vitro and in vivo.

Conclusions

This study suggests that combined use of a PARP inhibitor with doxorubicin, a DNA damaging agent, might be effective in the treatment of osteosarcoma patients, especially in the poor-prognostic subgroups of osteosarcoma expressing PARP1, γH2AX, or BRCA1/2.

Cell Cycle Resolved Measurements of Poly(ADP-Ribose) Formation and DNA Damage Signaling by Quantitative Image-Based Cytometry

Formation of poly(ADP-ribose) (PAR) marks intracellular stress signaling and is notably induced upon DNA damage. PAR polymerases (PARPs) catalyze PAR synthesis upon genotoxic stress and thereby recruit multiple proteins to damaged chromatin. PAR induction is transient and antagonized by the action of PAR glycohydrolase (PARG). Given that poly(ADP-ribosyl)ation (PARylation) is involved in genome integrity maintenance and other vital cellular functions, but also in light of the recent approval of PARP inhibitors for cancer treatments, reliable measurements of intracellular PAR formation have gained importance. Here we provide a detailed protocol for PAR measurements by quantitative image-based cytometry. This technique combines the high spatial resolution of single-cell microscopy with the advantages of cell population measurements through automated high-content imaging. Such upscaling of immunofluorescence-based PAR detection not only increases the robustness of the measurements through averaging across large cell populations but also allows for the discrimination of subpopulations and thus enables multivariate measurements of PAR levels and DNA damage signaling. We illustrate how this technique can be used to assess the dynamics of the cellular response to oxidative damage as well as to PARP inhibitor-induced genotoxicity in a cell cycle resolved manner. Due to the possibility to use any automated microscope for quantitative image-based cytometry, the presented method has widespread applicability in the area of PARP biology and beyond.

Olaparib for the treatment of breast cancer

INTRODUCTION

Mutations in BRCA1 and BRCA2 genes account for around 2-3% of breast cancer events and more than 10% of triple negative breast cancers. Olaparib (Lynparza®), an orally administered PARP inhibitor, demonstrated clinical benefit in a phase III trial for mutated BRCA-positive HER2 negative metastatic breast cancer. Areas covered: This review gives an overview of available preclinical and clinical data regarding olaparib, including its chemistry, mechanism of action, pharmacokinetics and pharmacodynamics, and evidence supporting antitumor efficacy and safety profile in breast cancer patients. Expert commentary: Olaparib improves progression-free survival in germline BRCA mutated HER2 negative metastatic breast cancer patients as compared to standard chemotherapy, with a manageable toxicity profile. Efficacy is of clinical relevance especially in the context of triple negative breast cancer. However, several aspects, such as sequencing or combination of these agents with other anticancer agents and identification of appropriate biomarkers, still need to be clearly defined.

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.

PARP-1 inhibition ameliorates elastase induced lung inflammation and emphysema in mice

COPD is associated with high morbidity and mortality and no effective treatment is available till date. We have previously reported that PARP-1 plays an important role in the establishment of airway inflammation associated with asthma and ALI. In the present work, we have evaluated the beneficial effects of PARP-1 inhibition on COPD pathogenesis utilizing elastase induced mouse model of the disease. Our data show that PARP-1 inhibition by olaparib significantly reduced the elastase-induced recruitment of inflammatory cells particularly neutrophils in the lungs of mice when administered at a dose of 5 mg/kg b.wt (i.p.). Reduction in the lung inflammation was associated with suppressed myeloperoxidase activity. Further, the drug restored the redox status in the lung tissues towards normal as reflected by the levels of ROS, GSH and MDA. Olaparib administration prior to elastase instillation blunted the phosphorylation of P65-NF-κB at Ser 536 without altering phosphorylation of its inhibitor IκBα in the lungs. Furthermore, olaparib down regulated the elastase-induced expression of NF-κB dependent pro-inflammatory cytokines (TNF-A, IL-6), chemokine (MIP-2) and growth factor (GCSF) severely both at the mRNA and protein levels. Additionally, PARP-1 heterozygosity suppressed the recruitment of inflammatory cells and production of TNF-A, IL-6, MIP-2 and GCSF in the BALF to the similar extent as exhibited by olaparib administration. Finally, PARP-1 inhibition by olaparib or gene deletion protected against elastase-induced emphysema markedly. Overall, our data strongly suggest that PARP-1 plays a critical role in elastase induced lung inflammation and emphysema, and thus may be a new drug target candidate in COPD.

PARADIGM-2: Two parallel phase I studies of olaparib and radiotherapy or olaparib and radiotherapy plus temozolomide in patients with newly diagnosed glioblastoma, with treatment stratified by MGMT status

Glioblastoma has a dismal prognosis and molecular targeted agents have failed to improve outcomes to date. PARADIGM-2 is a phase I dose escalation study evaluating olaparib plus radiotherapy ± temozolomide in newly diagnosed glioblastoma, using MGMT methylation status to stratify patients and inform treatment schedules.