piperidines and olaparib

PARP inhibitors are effective in different types of tumors such as ovarian, breast, prostate and pancreatic cancer. Many studies are in progress and may lead to prescription evolution. PARP inhibitors prescription is almost reserved to patients with a constitutional BRCA mutation or a somatic BRCA alteration or a tumor with a deficiency in homologous recombination. Nowadays, the diagnosis of homologous recombination deficit, HRD, is possible with the prescription of a myChoice CDx (Myriad) test. PARP inhibitors are studied in association with chemotherapy and targeted therapies but also with radiotherapy and with immune checkpoint inhibitors. Access to PARP inhibitors is challenged with the emergence of resistance mechanism. Various trials are now studying the possibility of reversing these resistance mechanisms.

Topics: Breast Neoplasms; DNA Damage; DNA Repair-Deficiency Disorders; Drug Resistance, Neoplasm; Female; Genes, BRCA1; Genes, BRCA2; Homologous Recombination; Humans; Indazoles; Indoles; Male; Ovarian Neoplasms; Pancreatic Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Prostatic Neoplasms; Recombinational DNA Repair

New molecular therapeutic approaches have emerged in recent years for advanced gynaecological cancers, including targeted therapies such as poly-ADP-ribose polymerase inhibitors (PARPi). These have demonstrated efficacy in high-grade serous ovarian cancers in patients carrying a mutation in the BRCA gene, which predisposes them to breast and ovarian cancers. Clinical and pre-clinical data suggest that the activity of PARPi inhibitors may not be limited to BRCA mutated tumours and may involve the homologous recombination pathway. These data raise the question of the potential efficacy of PARPi in advanced endometrial and cervical cancers where treatment options are currently limited. At present, there are few data available on the activity of PARPi in endometrial and cervical cancers, but some results seem promising. In this review, we present a synthesis of the available studies concerning PARPi in endometrial and cervical cancer.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cisplatin; Clinical Trials as Topic; DNA Damage; DNA Repair-Deficiency Disorders; Endometrial Neoplasms; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Papillomavirus Infections; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Uterine Cervical Neoplasms

In early stages, standard treatment is adjuvant chemotherapy, consisting of platinum-based combination for 6 cycles, especially in serous and endometrioid high grade carcinomas. In advanced stages, indication of neoadjuvant chemotherapy must be discussed on a case-by-case basis in multidisciplinary meetings (MDM). Bevacizumab can also be considered in the neoadjuvant setting in some circumstances, always after discussion in MDM. Carboplatin plus paclitaxel every 21 days, with or without bevacizumab remains the standard of care for first-line chemotherapy. Inhibitors of poly-(ADP-riboses) polymerases (PARPi) have been approved and are reimbursed as maintenance monotherapy in tumors carrying BRCA1 or BRCA2 mutation after complete or partial response to chemotherapy. Two recent studies demonstrated the efficacy of PARPi on progression free survival, one for niraparib single-agent in patients with high-grade ovarian carcinoma regardless of BRCA status, the other one for the combination of bevacizumab and olaparib in patients with high grade carcinoma, with positive test for homologous recombination DNA repair deficiency (regardless of BRCA status). These two new modalities of maintenance therapy are now available in compassionate use programs or post compassionate use programs. Depending on pending decisions upon reimbursement, these indications might be somewhat modified.

Topics: Algorithms; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Carboplatin; Carcinoma, Ovarian Epithelial; Chemotherapy, Adjuvant; Drug Administration Schedule; Female; Genes, BRCA1; Genes, BRCA2; Humans; Indazoles; Maintenance Chemotherapy; Neoadjuvant Therapy; Neoplasm Grading; Neoplasm Staging; Ovarian Neoplasms; Paclitaxel; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors

Over the past years, several studies have demonstrated that defects in DNA damage response and repair (DDR) genes are present in a significant proportion of patients with prostate cancer. These alterations, particularly mutations in BRCA2, are known to be associated with an increased risk of developing prostate cancer and more aggressive forms of the disease. There is growing evidence that certain DDR gene aberrations confer sensitivity to poly-(ADP ribose) polymerase inhibitors and/or platinum chemotherapy, while other defects might identify cases that are more likely to benefit from immune checkpoint inhibition. The potential prognostic impact and relevance for treatment selection together with the decreasing costs and broader accessibility to next-generation sequencing have already resulted in the increased frequency of genetic profiling of prostate tumours. Remarkably, almost half of all DDR genetic defects can occur in the germline, and prostate cancer patients identified as mutation carriers, as well as their families, will require appropriate genetic counselling. In this review, we summarise the current knowledge regarding the biology and clinical implications of DDR defects in prostate cancer, and outline how this evidence is prompting a change in the treatment landscape of the disease.

Topics: Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; Clinical Trials as Topic; DNA Damage; DNA Repair; Genes, BRCA1; Genes, BRCA2; Germ-Line Mutation; High-Throughput Nucleotide Sequencing; Humans; Immune Checkpoint Inhibitors; Indazoles; Indoles; Male; Phthalazines; Piperazines; Piperidines; Platinum Compounds; Poly(ADP-ribose) Polymerase Inhibitors; Precision Medicine; Prognosis; Prostatic Neoplasms

Treatment of metastatic prostate cancer has evolved significantly over the past decade. Palliative therapy has, historically, consisted of androgen deprivation, chemotherapy and different radiation therapy approaches. More recently, breakthrough therapy with the use of poly-ADP-ribose polymerase (PARP) inhibitors has led to significant improvement in the outcome of patients with metastatic prostate cancer who harbor certain genetic mutations. This concise review focuses on the 3 PARP inhibitors that have shown activity in metastatic prostate cancer.

Topics: Animals; BRCA1 Protein; BRCA2 Protein; Genetic Predisposition to Disease; Humans; Indazoles; Indoles; Male; Mutation; Neoplasm Metastasis; Phenotype; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Prostatic Neoplasms; PTEN Phosphohydrolase; Treatment Outcome

We aimed to evaluate the risk of PARP inhibitors (PARPis) causing pneumonitis in randomized controlled trials (RCTs) and in the real-world practice.. First, a systematic review based on meta-analysis was conducted. RCTs with available data reporting pneumonitis events for PARPis were eligible for analysis. Second, we conducted a disproportionality analysis based on data from the FDA Adverse Event Reporting System (FAERS) database to characterize the main features of PARPi-related pneumonitis.. PARPis increased the risk of pneumonitis that can result in serious outcomes and tend to occur early. Early recognition and management of PARPi-pneumonitis is of vital importance in clinical practice. The mechanisms and risk factors should be studied further to improve clinical understanding and innovative treatment strategies for these diseases.

Topics: Adverse Drug Reaction Reporting Systems; Humans; Incidence; Indazoles; Neoplasms; Phthalazines; Piperazines; Piperidines; Pneumonia; Poly(ADP-ribose) Polymerase Inhibitors; Randomized Controlled Trials as Topic; Time Factors

We aimed to evaluate comparative safety and tolerability of the approved PARP inhibitors in people with cancer.. Eligible studies included randomized controlled trials comparing an approved PARP inhibitor (fluzoparib, olaparib, rucaparib, niraparib, or talazoparib) with placebo or chemotherapy in cancer patients. Outcomes of interest included: serious adverse event (SAE), discontinuation due to adverse event (AE), interruption of treatment due to AE, dose reduction due to AE, and specific grade 1-5 AEs.. Ten trials including 3763 participants and six treatments (olaparib, rucaparib, niraparib, talazoparib, placebo, and protocol-specified single agent chemotherapy) were identified. SAE and discontinuation of treatment did not differ significantly among the four approved PARP inhibitors. Regarding interruption of treatment and dose reduction due to AE, statistically significant differences and statistically non-significant trend were observed. Talazoparib is associated with a higher risk of interruption of treatment and dose reduction (excluding rucaparib) due to AE as compared with the other drugs. Niraparib showed a trend of lower risk of AE related dose reduction as compared with the other drugs. Furthermore, there were significant differences in specific grade 1-5 AE among the four drugs.. The safety profile of the four approved PARP inhibitors is comparable in terms of SAE and AE-related discontinuation of treatment. Statistically significant differences in the AEs spectrum and AEs related dose interruption and dose reduction demonstrated the prompt identification of AE and dose personalization seem mandatory to obtain maximal benefit from PARP inhibitors.

Topics: Humans; Indazoles; Indoles; Neoplasms; Network Meta-Analysis; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Randomized Controlled Trials as Topic

The standard treatment for advanced ovarian cancer is cytoreductive surgery followed by cytotoxic chemotherapy. However, it has high risk of recurrence and poor prognosis. Poly(ADPribose) polymerase (PARP) inhibitors selectively target DNA double-strand breaks (DSBs) in tumor cells that cannot be repaired and induce the synthetic lethality of BRCA1/2 mutation cancers. PARP inhibitors are clinically used to treat recurrent ovarian cancer and show significant efficacy in ovarian cancer patients with homologous recombination repair (HRR) pathway defects. PARP inhibitors also have significant clinical benefits in patients without HR defects. With the increasingly extensive clinical application of PARP inhibitors, the possibility of acquiring drug resistance is high. Therefore, clinical strategies should be adopted to manage drug resistance of PARP inhibitors. This study aims to summarize the indications and toxicity of PARP inhibitors, the mechanism of action, targeted treatment of drug resistance, and potential methods to manage drug-resistant diseases. We used the term "ovarian cancer" and the names of each PARP inhibitor as keywords to search articles published in the Medical Subject Headings (MeSH) on Pubmed, along with the keywords "clinicaltrials.gov" and "google.com/patents" as well as "uspto.gov." The FDA has approved olaparib, niraparib, and rucaparib for the treatment of recurrent epithelial ovarian cancer (EOC). Talazoparib and veliparib are currently in early trials and show promising clinical results. The mechanism underlying resistance to PARP inhibitors and the clinical strategies to overcome them remain unclear. Understanding the mechanism of resistance to PARP inhibitors and their relationship with platinum resistance may help with the development of antiresistance therapies and optimization of the sequence of drug application in the future clinical treatment of ovarian cancer.

Topics: Antineoplastic Agents; Benzimidazoles; BRCA1 Protein; BRCA2 Protein; Carcinoma, Ovarian Epithelial; DNA Repair; Drug Resistance, Neoplasm; Female; Humans; Indazoles; Indoles; Neoplasm Recurrence, Local; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases

The use of poly (ADP-ribose) polymerase (PARP) inhibitors in the front-line management of advanced ovarian cancer has recently emerged as an exciting strategy with the potential to improve outcomes for patients with advanced ovarian cancer. In this article, we review the results of four recently published Phase III randomised controlled trials evaluating the use of PARP inhibitors in the primary treatment of ovarian cancer (SOLO1, PRIMA, PAOLA-1, and VELIA). Collectively, the studies suggest that PARP maintenance in the upfront setting is most beneficial among patients with BRCA-associated ovarian cancers (hazard ratios range from 0.31 to 0.44), followed by patients with tumours that harbour homologous recombination deficiencies (hazard ratios range from 0.33 to 0.57). All three studies that included an all-comer population were able to demonstrate benefit of PARP inhibitors, regardless of biomarker status. The FDA has approved olaparib for front-line maintenance therapy among patients with BRCA-associated ovarian cancers, and niraparib for all patients, regardless of biomarker status. In determining which patients should be offered front-line maintenance PARP inhibitors, and which agent to use, there are multiple factors to consider, including FDA indication, dosing preference, toxicity, risks versus benefits for each patient population, and cost. There are ongoing studies further exploring the front-line use of PARP inhibitors, including the potential downstream effects of PARP-inhibitor resistance in the recurrent setting, combining PARP-inhibitors with other anti-angiogenic drugs, immunotherapeutic agents, and inhibitors of pathways implicated in PARP inhibitor resistance.

Topics: Angiogenesis Inhibitors; Antineoplastic Agents, Immunological; Antineoplastic Combined Chemotherapy Protocols; BRCA1 Protein; BRCA2 Protein; Clinical Trials, Phase III as Topic; Cost-Benefit Analysis; Drug Approval; Drug Costs; Drug Resistance, Neoplasm; Female; Humans; Indazoles; Maintenance Chemotherapy; Mutation; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Progression-Free Survival; Randomized Controlled Trials as Topic; Recombinational DNA Repair; United States; United States Food and Drug Administration

Breast and ovarian cancer are common malignancies among older adults, causing significant morbidity and mortality. Although most cases of breast and ovarian cancer are sporadic, a significant proportion is caused by mutations in cancer susceptibility genes, most often breast cancer susceptibility genes (BRCA) 1 and 2. Furthermore, some breast and ovarian tumors are phenotypically similar to those with BRCA mutations, a phenomenon known as "BRCAness". BRCA mutations and "BRCAness" lead to defects in DNA repair, which may be a target for therapeutic agents such as Poly ADP-Ribose Polymerase (PARP) inhibitors. PARP inhibitors are novel medications which lead to double-strand breaks resulting in cell death due to synthetic lethality, and which have been shown to be effective in patients with advanced breast and ovarian cancers with or without BRCA mutations. Three different PARP inhibitors (olaparib, niraparib, and rucaparib) have been approved for the treatment of ovarian cancer and one (olaparib) for breast cancer harboring BRCA mutations. Here, we review the currently available evidence regarding the use of PARP inhibitors for the treatment of patients with breast and ovarian cancer, with a particular focus on the inclusion of older adults in clinical trials of these therapies. Additionally, we provide an overview of currently ongoing studies of PARP inhibitors in breast and ovarian cancer, and include recommendations for increasing the evidence-base for using these medications among older patients.

Topics: Aged; Aged, 80 and over; Breast Neoplasms; DNA Repair; Female; Genes, BRCA1; Genes, BRCA2; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Synthetic Lethal Mutations

Poly (ADP-ribose) polymerase (PARP) inhibitors have provided great clinical benefits to ovarian cancer patients. To date, three PARP inhibitors, namely, olaparib, rucaparib and niraparib have been approved for the treatment of ovarian cancer in the United States. Homologous recombination deficiency (HRD) and platinum sensitivity are prospective biomarkers for predicting the response to PARP inhibitors in ovarian cancers. Preclinical data have focused on identifying the gene aberrations that might generate HRD and induce sensitivity to PARP inhibitors in vitro in cancer cell lines or in vivo in patient-derived xenografts. Clinical trials have focused on genomic scar analysis to identify biomarkers for predicting the response to PARP inhibitors. Additionally, researchers have aimed to investigate mechanisms of resistance to PARP inhibitors and strategies to overcome this resistance. Combining PARP inhibitors with HR pathway inhibitors to extend the utility of PARP inhibitors to BRCA-proficient tumours is increasingly foreseeable. Identifying the population of patients with the greatest potential benefit from PARP inhibitor therapy and the circumstances under which patients are no longer suited for PARP inhibitor therapy are important. Further studies are required in order to propose better strategies for overcoming resistance to PARP inhibitor therapy in ovarian cancers.

Topics: Drug Resistance, Neoplasm; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases

Genomic instability is a hallmark of cancer, and often is the result of altered DNA repair capacities in tumour cells. DNA damage repair defects are common in different cancer types; these alterations can also induce tumour-specific vulnerabilities that can be exploited therapeutically. In 2009, a first-in-man clinical trial of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib clinically validated the synthetic lethal interaction between inhibition of PARP1, a key sensor of DNA damage, and BRCA1/BRCA2 deficiency. In this review, we summarize a decade of PARP inhibitor clinical development, a work that has resulted in the registration of several PARP inhibitors in breast (olaparib and talazoparib) and ovarian cancer (olaparib, niraparib and rucaparib, either alone or following platinum chemotherapy as maintenance therapy). Over the past 10 years, our knowledge on the mechanism of action of PARP inhibitor as well as how tumours become resistant has been extended, and we summarise this work here. We also discuss opportunities for expanding the precision medicine approach with PARP inhibitors, identifying a wider population who could benefit from this drug class. This includes developing and validating better predictive biomarkers for patient stratification, mainly based on homologous recombination defects beyond BRCA1/BRCA2 mutations, identifying DNA repair deficient tumours in other cancer types such as prostate or pancreatic cancer, or by designing combination therapies with PARP inhibitors.

Topics: BRCA1 Protein; BRCA2 Protein; Breast Neoplasms; Female; Genomic Instability; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors

The single agent activity of PARP inhibitors (PARPi) in germline BRCA mutated (gBRCAm) breast and ovarian cancer suggests untapped potential for this new class of drug in breast cancer. The US Food and Drug Administration has approved three PARPi (olaparib, rucaparib, and niraparib) so far to treat certain ovarian cancers, including those with gBRCAm and olaparib for treatment of gBRCAm breast cancers. Several PARPi are now under clinical development for breast cancer in the various treatment settings. Recently, two phase III trials of olaparib (OlympiaD) and talazoparib (EMBRACA) demonstrated 3-month progression-free survival improvement with PARPi compared to physician's choice single agent chemotherapy in metastatic gBRCAm breast cancer. To date, PARPi seems less efficacious in metastatic breast cancer patients than those with BRCA mutated platinum-sensitive recurrent ovarian cancer, perhaps reflecting the biologic heterogeneity and low somatic BRCA mutation rate in breast cancer. The use of PARPi is gradually evolving, including combination strategies with chemotherapy, targeted agents, radiotherapy, or immunotherapy in women with and without gBRCAm. The role of predictive biomarkers, including molecular signatures and homologous recombination repair deficiency scores based on loss of heterozygosity and other structural genomic aberrations, will be crucial to identify a subgroup of patients who may have benefit from PARPi. An improved understanding of the mechanisms underlying PARPi clinical resistance will also be important to enable the development of new approaches to increase efficacy. This is a field rich in opportunity, and the coming years should see a better understanding of which breast cancer patients we should treat with PARPi and where these agents should come in over the course of treatment.

Topics: BRCA1 Protein; BRCA2 Protein; Breast Neoplasms; Female; Humans; Indazoles; Indoles; Neoplasm Recurrence, Local; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Progression-Free Survival

Triple-negative breast cancer (TNBC) accounts for approximately 15-20% of all breast cancers and is characterized by a lack of immunohistochemical expression of estrogen receptors (ER), progesterone receptors (PR) and HER2. TNBC is associated with poor long-term outcomes compared with other breast cancer subtypes. Many of these tumors are also basal-like cancers which are characterized by an aggressive biological behavior with a distant recurrence peak observed early at 3 years following diagnosis. Furthermore, metastatic TNBC bears a dismal prognosis with an average survival of 12 months. Although the prevalence of genetic alterations among women with TNBC differs significantly by ethnicity, race and age, BRCA mutations (including both germline mutations and somatic genetic aberrations) are found in up to 20-25% of unselected patients and especially in those of the basal-like immunophenotype. Therefore, defects in the DNA repair pathway could represent a promising therapeutic target for this subgroup of TNBC patients. Poly(ADP-ribose) polymerase (PARP) inhibitors exploit this deficiency through synthetic lethality and have emerged as promising anticancer therapies, especially in BRCA1 or BRCA2 mutation carriers. Several PARP inhibitors are currently being evaluated in the adjuvant, neo-adjuvant, and metastatic setting for the treatment of breast cancer patients with a deficient homologous recombination pathway. In this article, we review the major molecular characteristics of TNBC, the mechanisms of homologous recombination, and the role of PARP inhibition as an emerging therapeutic strategy.

Topics: Benzamides; Female; Genes, BRCA1; Genes, BRCA2; Homologous Recombination; Humans; Indazoles; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Triple Negative Breast Neoplasms

Use of poly(ADP-ribose) polymerase (PARP) inhibitors has greatly increased over the past 5 years. With several new Food and Drug Administration (FDA) approvals, three PARP inhibitors have entered into standard of care treatment for epithelial ovarian cancer (including ovarian, fallopian tube, and primary peritoneal cancer). Olaparib and rucaparib currently have indications for treatment of recurrent BRCA mutant ovarian cancer. Olaparib, rucaparib, and niraparib all have indications for maintenance therapy in recurrent platinum-sensitive ovarian cancer after response to platinum-based therapy. In our practice, we use both olaparib and rucaparib in the recurrent setting, and all three PARP inhibitors in the maintenance setting. Choice of which PARP inhibitor to use in either setting is largely based upon baseline laboratory values, number of prior therapies, and presence of a BRCA mutation and/or homologous recombination deficiency (HRD). As (HRD) and other biomarker assessments continue to improve, we anticipate being able to better identify which patients might most benefit from PARP inhibitor therapy in the future. The clinically available PARP inhibitors are currently undergoing extensive investigations in clinical trials. Other newer agents such as talazoparib, veliparib, 2X-121, and CEP-9722 are in earlier stages of development. As more FDA-approved indications for PARP inhibitor therapy in ovarian cancer become available, we anticipate the decision of which PARP inhibitor to use will become increasingly complex.

Topics: Antineoplastic Combined Chemotherapy Protocols; Benzimidazoles; BRCA1 Protein; BRCA2 Protein; Carbazoles; Carcinoma, Ovarian Epithelial; Female; Humans; Indazoles; Indoles; Neoplasm Recurrence, Local; Ovarian Neoplasms; Ovary; Phthalazines; Phthalimides; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors

Poly(ADP-ribose) polymerases(PARP) synthesize the ADP-ribose polymers onto proteins and play a role in DNA repair. PARP inhibitors block the repair of single-strand breaks, which in turn gives rise to double-strand breaks during DNA replication. Thus, PARP inhibitors elicit synthetic lethality in cancer with BRCA1/2 loss-of-function mutations that hamper homologous recombination repair of double-strand breaks. Olaparib, the first-in-class PARP inhibitor, was approved for treatment of BRCA-mutated ovarian cancer in Europe and the United States in 2014. Other PARP inhibitors under clinical trials include rucaparib, niraparib, veliparib, and the "PARP-trapping" BMN-673. BRCA1/2 sequencing is an FDA-approved companion diagnostics, which predicts the cancer vulnerability to PARP inhibition. Together, synthetic lethal PARP inhibition is a novel promising strategy for cancer intervention even in cases without prominent driver oncogenes.

Topics: Antineoplastic Agents; Benzimidazoles; BRCA1 Protein; BRCA2 Protein; DNA Breaks, Double-Stranded; DNA Replication; DNA, Single-Stranded; Enzyme Inhibitors; Humans; Indazoles; Indoles; Molecular Targeted Therapy; Mutation; Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Recombinational DNA Repair

Clinical investigation of poly(ADP-ribose) polymerase (PARP) inhibitors for ovarian cancer treatment has rapidly evolved from observations of single-agent in vitro activity of these agents in BRCA-deficient cancer cells in 2005 to the initiation of multiple phase III studies in 2013. With clinical trial design and treatment of ovarian cancer increasingly based on histological and molecular characteristics, PARP inhibitors are on the horizon of becoming the first biologic agents to be used to treat ovarian cancer based upon pre-selection characteristics of the patient's cancer. PARP inhibitors are most active in ovarian cancers that have defects or aberrations in DNA repair; use of these agents has been of particular interest in high grade serous cancers (HGSC), where studies have shown that ~50% of HGSC have abnormalities of DNA repair through BRCA germline and somatic mutation, post-translational changes of BRCA, and abnormalities of other DNA repair molecules. In addition, as aberrant DNA pathways in other histological subtypes of ovarian cancer are identified, and through the combination of PARP inhibitors with other biologic agents, the pool of eligible patients who may benefit from PARP inhibitors will likely expand. Pending review by the Food and Drug Administration (FDA) and the outcome of confirmatory phase III studies, PARP inhibitors could become the first FDA-approved biologic agent for ovarian cancer and also the first new FDA-approval in ovarian cancer since carboplatin and gemcitabine were approved for platinum sensitive ovarian cancer in 2006. This review discusses the PARP inhibitors that are currently in testing for ovarian cancer treatment and the future of this class of anti-cancer agents.

Topics: Antineoplastic Agents; Benzimidazoles; DNA Repair; Female; Genes, BRCA1; Genes, BRCA2; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors

Topics: Carcinoma, Ovarian Epithelial; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Platinum; Poly(ADP-ribose) Polymerase Inhibitors

In the base case, olaparib was the more cost-effective treatment regimen. The ICERs for olaparib and niraparib compared to placebo were NT$1,804,785 and NT$2,340,265 per PFS-LY, respectively. Tornado analysis showed that PFS and the total resource use cost of niraparib regimen for patients without. Olaparib was estimated to be less cost and more effective compared to niraparib as maintenance therapy for patients with recurrent platinum-sensitive ovarian cancer.

Topics: Cost-Benefit Analysis; Female; Humans; Indazoles; Neoplasm Recurrence, Local; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines

Poly-(ADP-ribose) polymerase 1 and 2 (PARP1 and PARP2) are key enzymes in the DNA damage response. Four different inhibitors (PARPi) are currently in the clinic for treatment of ovarian and breast cancer. Recently, histone PARylation Factor 1 (HPF1) has been shown to play an essential role in the PARP1- and PARP2-dependent poly-(ADP-ribosylation) (PARylation) of histones, by forming a complex with both enzymes and altering their catalytic properties. Given the proximity of HPF1 to the inhibitor binding site both PARPs, we hypothesized that HPF1 may modulate the affinity of inhibitors toward PARP1 and/or PARP2. Here we demonstrate that HPF1 significantly increases the affinity for a PARP1 - DNA complex of some PARPi (i.e., olaparib), but not others (i.e., veliparib). This effect of HPF1 on the binding affinity of Olaparib also holds true for the more physiologically relevant PARP1 - nucleosome complex but does not extend to PARP2. Our results have important implications for the interpretation of PARP inhibition by current PARPi as well as for the design and analysis of the next generation of clinically relevant PARP inhibitors.

Topics: Antineoplastic Agents; Benzamides; Benzimidazoles; Binding Sites; Carrier Proteins; Catalysis; Catalytic Domain; DNA Repair Enzymes; Humans; Indazoles; Indoles; Nuclear Proteins; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Protein Binding

Topics: Antineoplastic Agents; Clinical Trials as Topic; Drug Approval; Female; Humans; Indazoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors

DNA repair inhibitors are one of the latest additions to cancer chemotherapy. In general, chemotherapy produces DNA damage but tumoral cells may become resistant if enzymes involved in DNA repair are overexpressed and are able to reverse DNA damage. One of the most successful drugs based on modulating DNA repair are the poly(ADP-ribose) polymerase 1 (PARP1) inhibitors. Several PARP1 inhibitors have been recently developed and approved for clinical treatments. We envisaged that PARP inhibition could be potentiated by simultaneously modulating the expression of PARP 1 and the enzyme activity, by a two-pronged strategy. A noncanonical G-quadruplex-forming sequence within the PARP1 promoter has been recently identified. In this study, we explored the potential binding of clinically approved PARP1 inhibitors to the G-quadruplex structure found at the gene promoter region. The results obtained by NMR, CD, and fluorescence titration confirmed by molecular modeling demonstrated that two out the four PARP1 inhibitors studied are capable of forming defined complexes with the PARP1 G-quadruplex. These results open the possibility of exploring the development of better G-quadruplex binders that, in turn, may also inhibit the enzyme.

Topics: Benzimidazoles; DNA; G-Quadruplexes; Humans; Indazoles; Magnetic Resonance Spectroscopy; Models, Molecular; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Promoter Regions, Genetic

Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors exhibit promising activity against ovarian cancers, but their efficacy can be limited by acquired drug resistance. This study explores the role of autophagy in regulating the sensitivity of ovarian cancer cells to PARP inhibitors.. Induction of autophagy was detected by punctate LC3 fluorescence staining, LC3I to LC3II conversion on Western blot analysis, and electron microscopy. Enhanced growth inhibition and apoptosis were observed when PARP inhibitors were used with hydroxychloroquine, chloroquine (CQ), or LYS05 to block the hydrolysis of proteins and lipids in autophagosomes or with small interfering RNA against ATG5 or ATG7 to prevent the formation of autophagosomes. The preclinical efficacy of the combination of CQ and olaparib was evaluated with a patient-derived xenograft (PDX) and the OVCAR8 human ovarian cancer cell line.. Four PARP inhibitors (olaparib, niraparib, rucaparib, and talazoparib) induced autophagy in a panel of ovarian cancer cells. Inhibition of autophagy with CQ enhanced the sensitivity of ovarian cancer cells to PARP inhibitors. In vivo, olaparib and CQ produced additive growth inhibition in OVCAR8 xenografts and a PDX. Olaparib inhibited PARP activity, and this led to increased reactive oxygen species (ROS) and an accumulation of γ-H2AX. Inhibition of autophagy also increased ROS and γ-H2AX and enhanced the effect of olaparib on both entities. Treatment with olaparib increased phosphorylation of ATM and PTEN while decreasing the phosphorylation of AKT and mTOR and inducing autophagy.. PARP inhibitor-induced autophagy provides an adaptive mechanism of resistance to PARP inhibitors in cancer cells with wild-type BRCA, and a combination of PARP inhibitors with CQ or other autophagy inhibitors could improve outcomes for patients with ovarian cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Autophagy; Cell Line, Tumor; Chloroquine; Drug Resistance, Neoplasm; Drug Synergism; Female; Humans; Indazoles; Mice, Nude; Mice, SCID; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Xenograft Model Antitumor Assays

Topics: Benzimidazoles; Clinical Trials as Topic; Female; Genes, BRCA1; Genes, BRCA2; Humans; Indazoles; Maintenance Chemotherapy; Ovarian Neoplasms; Phenotype; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors

The deletion of 11q (del(11q)) invariably comprises ATM gene in chronic lymphocytic leukemia (CLL). Concomitant mutations in this gene in the remaining allele have been identified in 1/3 of CLL cases harboring del(11q), being the biallelic loss of ATM associated with adverse prognosis. Although the introduction of targeted BCR inhibition has significantly favored the outcomes of del(11q) patients, responses of patients harboring ATM functional loss through biallelic inactivation are unexplored, and the development of resistances to targeted therapies have been increasingly reported, urging the need to explore novel therapeutic approaches. Here, we generated isogenic CLL cell lines harboring del(11q) and ATM mutations through CRISPR/Cas9-based gene-editing. With these models, we uncovered a novel therapeutic vulnerability of del(11q)/ATM-mutated cells to dual BCR and PARP inhibition. Ex vivo studies in the presence of stromal stimulation on 38 CLL primary samples confirmed a synergistic action of the combination of olaparib and ibrutinib in del(11q)/ATM-mutated CLL patients. In addition, we showed that ibrutinib produced a homologous recombination repair impairment through RAD51 dysregulation, finding a synergistic link of both drugs in the DNA damage repair pathway. Our data provide a preclinical rationale for the use of this combination in CLL patients with this high-risk cytogenetic abnormality.

Topics: Adenine; Animals; Antineoplastic Combined Chemotherapy Protocols; Ataxia Telangiectasia Mutated Proteins; Cell Line, Tumor; Chromosome Deletion; Chromosomes, Human, Pair 11; CRISPR-Cas Systems; Drug Synergism; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Mice; Mutagenesis, Site-Directed; Mutation; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Proto-Oncogene Proteins c-bcr; Pyrazoles; Pyrimidines; Xenograft Model Antitumor Assays

Polypharmacology plays an important role in defining response and adverse effects of drugs. For some mechanisms, experimentally mapping polypharmacology is commonplace, although this is typically done within the same protein class. Four PARP inhibitors have been approved by the FDA as cancer therapeutics, yet a precise mechanistic rationale to guide clinicians on which to choose for a particular patient is lacking. The four drugs have largely similar PARP family inhibition profiles, but several differences at the molecular and clinical level have been reported that remain poorly understood. Here, we report the first comprehensive characterization of the off-target kinase landscape of four FDA-approved PARP drugs. We demonstrate that all four PARP inhibitors have a unique polypharmacological profile across the kinome. Niraparib and rucaparib inhibit DYRK1s, CDK16 and PIM3 at clinically achievable, submicromolar concentrations. These kinases represent the most potently inhibited off-targets of PARP inhibitors identified to date and should be investigated further to clarify their potential implications for efficacy and safety in the clinic. Moreover, broad kinome profiling is recommended for the development of PARP inhibitors as PARP-kinase polypharmacology could potentially be exploited to modulate efficacy and side-effect profiles.

Topics: Antineoplastic Agents; Binding Sites; Cyclin-Dependent Kinases; Dyrk Kinases; HEK293 Cells; Humans; Indazoles; Indoles; Isoenzymes; Molecular Docking Simulation; Neoplasms; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Polypharmacology; Protein Binding; Protein Interaction Domains and Motifs; Protein Serine-Threonine Kinases; Protein Structure, Secondary; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Substrate Specificity

Olaparib was approved on December 19, 2014 by the US FDA as 4th-line therapy (and beyond) for patients with germline BRCA1/2 mutations; rucaparib was approved on December 19, 2016 as 3rd-line therapy (and beyond) for germline or somatic BRCA1/2-mutated recurrent disease. On October 23, 2019, niraparib was approved for treatment of women with damaging mutations in BRCA1/2 or other homologous recombination repair genes who had been treated with three or more prior regimens. We compared the cost-effectiveness of PARPi(s) with intravenous regimens for platinum-resistant disease.. Median progression-free survival (PFS) and toxicity data from regulatory trials were incorporated in a model which transitioned patients through response, hematologic complications, non-hematologic complications, progression, and death. Using TreeAge Pro 2017, each PARPi(s) was compared separately to non‑platinum-based and bevacizumab-containing regimens. Costs of IV drugs, managing toxicities, infusions, and supportive care were estimated using 2017 Medicare data. Incremental cost-effectiveness ratios (ICERs) were calculated and PFS was reported in quality adjusted life months for platinum-resistant populations.. Non‑platinum-based intravenous chemotherapy was most cost effective ($6,412/PFS-month) compared with bevacizumab-containing regimens ($12,187/PFS-month), niraparib ($18,970/PFS-month), olaparib ($16,327/PFS-month), and rucaparib ($16,637/PFS-month). ICERs for PARPi(s) were 3-3.5× times greater than intravenous non‑platinum-based regimens.. High costs of orally administered PARPi(s) were not mitigated or balanced by costs of infusion and managing toxicities of intravenous regimens typically associated with lower response and shorter median PFS. Balancing modest clinical benefit with costs of novel therapies remains problematic and could widen disparities among those with limited access to care.

Topics: Administration, Oral; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Carcinoma, Ovarian Epithelial; Cost-Benefit Analysis; Drug Costs; Female; Humans; Indazoles; Indoles; Infusions, Intravenous; Markov Chains; Models, Statistical; Neoplasm Recurrence, Local; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Quality of Life; United States

This study aims to describe the real-world experience, including the clinical and financial burden, associated with PARP inhibitors in a large community oncology practice.. Retrospective chart review identified patients prescribed olaparib, niraparib or rucaparib for maintenance therapy or treatment of recurrent ovarian, primary peritoneal or fallopian tube cancer across twelve gynecologic oncologists between December 2016 and November 2018. Demographic, financial and clinical data were extracted. One PARP cycle was defined as a single 28-day period. For patients treated with more than one PARPi, each course was described separately.. A total of 47 patients and 506 PARP cycles were identified (122 olaparib, 24%; 89 rucaparib, 18%; 294 niraparib, 58%). Incidence of grade ≥ 3 adverse events were similar to previously reported. Toxicity resulted in dose interruption, reduction and discontinuation in 69%, 63% and 29% respectively. Dose interruptions were most frequent for niraparib but resulted in fewer discontinuations (p-value 0.01). Mean duration of use was 7.46 cycles (olaparib 10.52, rucaparib 4.68, niraparib 7.34). Average cost of PARPi therapy was $8018 per cycle. A total of 711 phone calls were documented (call rate 1.4 calls/cycle) with the highest call volume required for care coordination, lab results and toxicity management.. Although the toxicity profile was similar to randomized clinical trials, this real-world experience demonstrated more dose modifications and discontinuations for toxicity management than previously reported. Furthermore, the clinical and financial burden of PARP inhibitors may be significant and future studies should assess the impact on patient outcomes.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Community Health Centers; Cost-Benefit Analysis; Dose-Response Relationship, Drug; Drug Costs; Female; Follow-Up Studies; Gynecology; Humans; Indazoles; Indoles; Medical Oncology; Medication Therapy Management; Middle Aged; Neoplasm Recurrence, Local; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Randomized Controlled Trials as Topic; Retrospective Studies; Workload

There are large randomized clinical trials-SOLO-1 (Olaparib Maintenance Monotherapy in Patients With BRCA Mutated Ovarian Cancer Following First Line Platinum Based Chemotherapy [December 2018]), PRIMA (A Study of Niraparib Maintenance Treatment in Patients With Advanced Ovarian Cancer Following Response on Front-Line Platinum-Based Chemotherapy [September 2019]), and PAOLA-1 (Platine, Avastin and Olaparib in 1st Line [December 2019])-reporting positive efficacy results for maintenance regimens for women with primary, advanced epithelial ovarian cancer. The findings resulted in approval by the US Food and Drug Administration of the treatments studied as of May 2020. However, there are pressing economic considerations given the many eligible patients and substantial associated costs.. To evaluate the cost-effectiveness of maintenance strategies for patients with (1) a BRCA variant, (2) homologous recombination deficiency without a BRCA variant, or (3) homologous recombination proficiency.. In this economic evaluation of the US health care sector using simulated patients with primary epithelial ovarian cancer, 3 decision trees were developed, one for each molecular signature. The maintenance strategies evaluated were olaparib (SOLO-1), olaparib-bevacizumab (PAOLA-1), bevacizumab (PAOLA-1), and niraparib (PRIMA). Base case 1 assessed olaparib, olaparib-bevacizumab, bevacizumab, and niraparib vs observation of a patient with a BRCA variant. Base case 2 assessed olaparib-bevacizumab, bevacizumab, and niraparib vs observation in a patient with homologous recombination deficiency without a BRCA variant. Base case 3 assessed olaparib-bevacizumab, bevacizumab, and niraparib vs observation in a patient with homologous recombination proficiency. The time horizon was 24 months. Costs were estimated from Medicare claims, wholesale acquisition prices, and published sources. Probabilistic sensitivity analyses with microsimulation were then conducted to account for uncertainty and assess model stability. One-way sensitivity analyses were also performed. The study was performed from January through June 2020.. Incremental cost-effectiveness ratios (ICERs) in US dollars per progression-free life-year saved (PF-LYS).. Assuming a willingness-to-pay threshold of $100 000/PF-LYS, none of the drugs could be considered cost-effective compared with observation. In the case of a patient with a BRCA variant, olaparib was the most cost-effective (ICER, $186 777/PF-LYS). The third-party payer price per month of olaparib would need to be reduced from approximately $17 000 to $9000 to be considered cost-effective. Olaparib-bevacizumab was the most cost-effective in the case of a patient with homologous recombination deficiency without a BRCA variant (ICER, $629 347/PF-LYS), and bevacizumab was the most cost-effective in the case of patient with homologous recombination proficiency (ICER, $557 865/PF-LYS). Even at a price of $0 per month, niraparib could not be considered cost-effective as a maintenance strategy for patients with homologous recombination proficiency.. The findings of this study suggest that, at current costs, maintenance therapy for primary ovarian cancer is not cost-effective, regardless of molecular signature. For certain therapies, lowering the drug price alone may not make them cost-effective.

Topics: Antineoplastic Agents, Immunological; Bevacizumab; Carcinoma, Ovarian Epithelial; Computing Methodologies; Cost-Benefit Analysis; Female; Genes, BRCA1; Genes, BRCA2; Homologous Recombination; Humans; Indazoles; Maintenance Chemotherapy; Medicare; Neoplasm Staging; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; United States

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).. 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.. 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.. 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.

Topics: Apoptosis; Blotting, Western; Cell Division; Cell Line, Tumor; Cell Survival; Child; DNA Damage; Dose-Response Relationship, Drug; Flow Cytometry; Fluorescent Antibody Technique; Histones; Humans; Isoenzymes; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Radiation Tolerance; Radiation, Ionizing; Real-Time Polymerase Chain Reaction; Rhabdomyosarcoma, Alveolar; Rhabdomyosarcoma, Embryonal

The aim was to evaluate the cost-effectiveness of niraparib compared with routine surveillance (RS), olaparib and rucaparib for the maintenance treatment of patients with recurrent ovarian cancer (OC).. A decision-analytic model estimated the cost per quality-adjusted life-year (QALY) gained for niraparib versus RS, olaparib, and rucaparib from a US payer perspective. The model considered recurrent OC patients with or without germline BRCA mutations (gBRCAmut and non-gBRCAmut), who were responsive to their last platinum-based chemotherapy regimen. Model health states were: progression-free disease, progressed disease and dead. Mean progression-free survival (PFS) was estimated using parametric survival distributions based on ENGOT-OV16/NOVA (niraparib phase III trial), ARIEL3 (rucaparib phase III trial) and Study 19 (olaparib phase II trial). Mean overall survival (OS) benefit was estimated as double the mean PFS benefit based on the relationship between PFS and OS observed in Study 19. Costs included: drug, chemotherapy, monitoring, adverse events, and terminal care. EQ-5D utilities were estimated from trial data.. Compared to RS, niraparib was associated with an incremental cost-effectiveness ratio (ICER) of US$68,287/QALY and US$108,287/QALY for gBRCAmut and non-gBRCAmut, respectively. Compared to olaparib and rucaparib, niraparib decreased costs and increased QALYs, with a cost saving of US$8799 and US$22,236 versus olaparib and US$198,708 and US$73,561 versus rucaparib for gBRCAmut and non-gBRCAmut, respectively.. Niraparib was estimated to be less costly and more effective compared to olaparib and rucaparib, and the ICER fell within an acceptable range compared to RS. Therefore, niraparib may be considered a cost-effective maintenance treatment for patients with recurrent OC.

Topics: Cost-Benefit Analysis; Decision Support Techniques; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Progression-Free Survival; Quality-Adjusted Life Years; Survival Rate; United States

This study aimed to evaluate the budget impact of niraparib and olaparib in patients with platinum-sensitive, recurrent ovarian cancer from a US third party payer perspective.. A budget impact model was constructed to assess the additional per member per month (PMPM) costs associated with the introduction of niraparib and olaparib, two poly ADP-ribose polymerase ribose polymerase (PARP) inhibitors recently approved to be used in platinum-sensitive, recurrent ovarian cancer patients with and without a gBRCA mutation. The model assessed both pharmacy costs and medical costs. Pharmacy costs included adjusted drug costs, coinsurance, and dispensing fees. Medical costs included costs associated with disease monitoring and management of adverse events from the treatment. Epidemiological data from the literature were used to estimate the target population size. The analysis used 1-year time frame, and patients were assumed on treatment until disease progression or death. All costs were computed in 2017 USD. One-way sensitivity analyses were conducted to evaluate the model robustness.. In a hypothetical plan of 1,000,000 members, 206 patients were estimated to be potential candidates for niraparib or olaparib maintenance treatment after applying all epidemiological parameters. At listed 30-day supply WAC prices of $14,750 for niraparib and $13,482 for olaparib, budget impacts of these two drugs were $0.169 PMPM and $0.156 PMPM, respectively, most of which were contributed by pharmacy costs. Sensitivity analyses suggested that assumptions around market share, platinum-sensitive rate after first treatment, and WAC prices affected results the most.. In this model, it was assumed that adopting niraparib and olaparib would not affect utilization of existing medications. Also, the estimated clinical parameters from clinical trials could differ from real-world data.

Topics: Antineoplastic Agents; Budgets; Female; Health Expenditures; Humans; Indazoles; Models, Econometric; Neoplasm Recurrence, Local; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Platinum; Poly(ADP-ribose) Polymerase Inhibitors; Progression-Free Survival; Survival Analysis; United States

FDA-approved treatments for platinum-sensitive recurrent ovarian cancer (PSROC) include bevacizumab and PARP inhibitors (PARPi); clinical decisions regarding therapy must be made prior to initiating chemotherapy. Using the American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO) value frameworks, we assessed relative values of concurrent/maintenance biologic therapies in PSROC.. Value scores were calculated for key maintenance therapies based on randomized controlled trials: bevacizumab (OCEANS, GOG 213); olaparib (Study 19, SOLO2); niraparib (NOVA); rucaparib (ARIEL3). Personalized value scorecards were constructed for patients with germline/somatic-BRCA mutations, homologous recombination deficiency (HRD), and wild-type BRCA (wBRCA). ASCO value scores assess clinical benefit, toxicity, long-term survival, symptom palliation, treatment-free interval, and quality of life (QOL). ESMO value scores assess clinical benefit, toxicity, and QOL.. ASCO scores were highest for maintenance PARPi in germline/somatic-BRCA mutation cohorts: olaparib (SOLO2) = 47, (Study 19) = 62; niraparib = 50; rucaparib = 54. HRD cohorts had slightly lower scores: niraparib = 46; rucaparib = 37. wBRCA cohorts had the lowest scores: niraparib = 26; rucaparib = 26; and olaparib (Study 19) = 32, as did patients receiving bevacizumab (OCEANS) = 35, (GOG 213) = 26. ESMO scores demonstrated high-value for maintenance PARPi in germline/somatic-BRCA mutation cohorts and low-value for bevacizumab and PARPi in wBRCA cohorts.. The value of maintenance PARPi therapy depends heavily on BRCA status, with the highest value scores in germline/somatic-BRCA mutation cohorts. Personalized value scorecards provide a visual aid to assess the harm-benefit balance of maintenance PARPi for PSROC.

Topics: Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Female; Genes, BRCA1; Genes, BRCA2; Germ-Line Mutation; Humans; Indazoles; Indoles; Maintenance Chemotherapy; Molecular Targeted Therapy; Neoplasm Recurrence, Local; Organoplatinum Compounds; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Precision Medicine; Randomized Controlled Trials as Topic

Topics: Cost-Benefit Analysis; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; United States

Topics: Cost-Benefit Analysis; Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; United States

Topics: Cost-Benefit Analysis; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; United States

Epithelial ovarian cancer (EOC) has one of the highest death to incidence ratios among all cancers. High grade serous ovarian carcinoma (HGSOC) is the most common and deadliest EOC histotype due to the lack of therapeutic options following debulking surgery and platinum/taxane-based chemotherapies. For recurrent chemosensitive HGSOC, poly(ADP)-ribose polymerase inhibitors (PARPi; olaparib, rucaparib, or niraparib) represent an emerging treatment strategy. While PARPi are most effective in homologous recombination DNA repair-deficient (HRD) HGSOCs, recent studies have observed a significant benefit in non-HRD HGSOCs. However, all HGSOC patients are likely to acquire resistance. Therefore, there is an urgent clinical need to understand PARPi resistance and to introduce novel combinatorial therapies to manage PARPi resistance and extend HGSOC disease-free intervals. In a panel of HGSOC cell lines, we established matched olaparib sensitive and resistant cells. Transcriptome analysis of the matched olaparib-sensitive vs -resistant cells revealed activation of the Wnt signaling pathway and consequently increased TCF transcriptional activity in PARPi-resistant cells. Forced activation of canonical Wnt signaling in several PARPi-sensitive cells via WNT3A reduced olaparib and rucaparib sensitivity. PARPi resistant cells were sensitive to inhibition of Wnt signaling using the FDA-approved compound, pyrvinium pamoate, which has been shown to promote downregulation of β-catenin. In both an HGSOC cell line and a patient-derived xenograft model, we observed that combining pyrvinium pamoate with olaparib resulted in a significant decrease in tumor burden. This study demonstrates that Wnt signaling can mediate PARPi resistance in HGSOC and provides a clinical rationale for combining PARP and Wnt inhibitors.

Topics: Animals; Cell Line, Tumor; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Neoplastic; Heterografts; Humans; Indazoles; Indoles; Mice; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Wnt Signaling Pathway

Mantle cell lymphoma (MCL) presents a therapeutic challenge. The B cell targeting agent, ibrutinib, is currently one of the most effective second-line therapies for MCL, but frequently leads to development of drug resistance, and short overall survival time upon relapse. Olaparib targets tumor cells with deficiencies in single-strand DNA break repair and thus may slow the development of genetic drug resistance. We found that the olaparib-ibrutinib combination significantly inhibits cell culture growth compared to either drug alone in two genetically distinct MCL cell lines. Moreover, these inhibitory effects are either additive or synergistic, depending on genetic background. Culture growth is inhibited due to increases in apoptosis, cell death, and cell cycle arrest, and the magnitude of each is cell line dependent. The additive and synergistic inhibition of this combination additionally supports a therapeutic strategy involving lower dosing of each drug to reduce potential side effects.

Topics: Adenine; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cell Proliferation; Drug Resistance, Neoplasm; Drug Synergism; Humans; Lymphoma, Mantle-Cell; Phthalazines; Piperazines; Piperidines; Pyrazoles; Pyrimidines; Tumor Cells, Cultured

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; BRCA1 Protein; BRCA2 Protein; Breast Neoplasms; Capecitabine; Female; Furans; Gene Expression Regulation, Neoplastic; Humans; Indazoles; Indoles; Ketones; Mutation; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Prognosis; Randomized Controlled Trials as Topic; Survival Analysis; Vinblastine; Vinorelbine

: Targeting PARP1 for synthetic lethality is a new strategy for breast cancers harboring germline mutations in BRCA. However, these mutations are rare, and reactivation of BRCA-mediated pathways may result in eventual resistance to PARP1 inhibitor therapy. Alternative synthetic lethality approaches targeting more common sporadic breast cancers and preinvasive ductal carcinoma

Topics: Apoptosis; Breast Neoplasms; Carcinoma, Intraductal, Noninfiltrating; Cell Cycle; Cell Line, Tumor; Chemoprevention; CRISPR-Cas Systems; DNA Breaks, Double-Stranded; DNA Repair; Female; Germ-Line Mutation; HeLa Cells; Humans; Indazoles; Neoplasm Invasiveness; Neoplasm Recurrence, Local; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Spheroids, Cellular; Synthetic Lethal Mutations; X-ray Repair Cross Complementing Protein 1

The recent approval of olaparib and niraparib as maintenance therapy can significantly affect the management of ovarian cancer. Clinical benefits, however, come with trade-offs in adverse events and costs.. To evaluate the cost-effectiveness of new ovarian cancer poly-ADP ribose polymerase (PARP) inhibitor therapies, olaparib and niraparib, as maintenance therapy for patients with platinum-sensitive recurrent ovarian cancer.. A decision tree model was constructed to evaluate the costs and effectiveness of olaparib and niraparib compared with placebo from a U.S. health care sector perspective. Costs included drug costs and costs of disease monitoring and management of adverse events throughout the treatment course. Costs were estimated from RED BOOK, Medicare reimbursement rates, and the literature and reported in 2017 U.S. dollars. Clinical effectiveness was measured in progression-free survival (PFS) life-years based on clinical trial results (NCT00753545, NCT01874353, and NCT01847274). The incremental cost-effectiveness ratio (ICER) was computed by dividing the incremental cost by the incremental effectiveness.. At base case, niraparib was the more effective treatment option with slightly higher PFS, followed by olaparib. The ICERs for niraparib and olaparib compared with common baseline placebo were $235K and $287K per PFS life-year, respectively, with olaparib extended-dominated by niraparib. Both drugs were associated with lower ICERs in patients with a gBRCA mutation than in patients without a gBRCA mutation. One-way sensitivity analysis suggested that drug prices and PFS could affect ICERs significantly, but the ICERs remained above $100K per PFS life-year within the plausible ranges of all parameters. Probabilistic sensitivity analysis suggested that niraparib was associated with higher net benefits compared with placebo only when willingness-to-pay (WTP) values were above $210K per PFS life-year thresholds.. PARP inhibitors niraparib and olaparib will extend PFS in platinum-sensitive recurrent ovarian cancer patients but are also associated with high drug acquisition costs. The base case ICERs were around or above $250K per PFS life-year in this model. No formal cost-effectiveness WTP threshold for health technology assessment exists in the United States. At a reference WTP of $100K per PFS life-year, the PARP inhibitors may not be cost-effective options.. This study was unfunded. The authors have nothing to disclose.

Topics: Clinical Decision-Making; Cost-Benefit Analysis; Female; Health Care Costs; Humans; Indazoles; Models, Economic; Neoplasm Recurrence, Local; Ovarian Neoplasms; Paclitaxel; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Progression-Free Survival; United States

Malignant pleural mesotheliomas (MPM) are most often surgically unresectable, and they respond poorly to current chemotherapy and radiation therapy. Between 23 and 64% of malignant pleural mesothelioma have somatic inactivating mutations in the BAP1 gene. BAP1 is a homologous recombination (HR) DNA repair component found in the BRCA1/BARD1 complex. Similar to BRCA1/2 deficient cancers, mutation in the BAP1 gene leads to a deficient HR pathway and increases the reliance on other DNA repair pathways. We hypothesized that BAP1-mutant MPM would require PARP1 for survival, similar to the BRCA1/2 mutant breast and ovarian cancers. Therefore, we used the clinical PARP1 inhibitors niraparib and olaparib to assess whether they could induce synthetic lethality in MPM. Surprisingly, we found that all MPM cell lines examined, regardless of BAP1 status, were addicted to PARP1-mediated DNA repair for survival. We found that niraparib and olaparib exposure markedly decreased clonal survival in multiple MPM cell lines, with and without BAP1 mutations. This clonal cell death may be due to the extensive replication fork collapse and genomic instability that PARP1 inhibition induces in MPM cells. The requirement of MPM cells for PARP1 suggests that they may generally arise from defects in HR DNA repair. More importantly, these data demonstrate that the PARP1 inhibitors could be effective in the treatment of MPM, for which little effective therapy exists.

Topics: Cell Line, Tumor; Clone Cells; DNA Repair; Humans; Indazoles; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mutation; Phthalazines; Piperazines; Piperidines; Pleural Neoplasms; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Synthetic Lethal Mutations; Tumor Suppressor Proteins; Ubiquitin Thiolesterase

Topics: Female; Humans; Indazoles; Indoles; Ovarian Neoplasms; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Treatment Outcome

Selective inhibitors could help unveil the mechanisms by which inhibition of poly(ADP-ribose) polymerases (PARPs) elicits clinical benefits in cancer therapy. We profiled 10 clinical PARP inhibitors and commonly used research tools for their inhibition of multiple PARP enzymes. We also determined crystal structures of these compounds bound to PARP1 or PARP2. Veliparib and niraparib are selective inhibitors of PARP1 and PARP2; olaparib, rucaparib, and talazoparib are more potent inhibitors of PARP1 but are less selective. PJ34 and UPF1069 are broad PARP inhibitors; PJ34 inserts a flexible moiety into hydrophobic subpockets in various ADP-ribosyltransferases. XAV939 is a promiscuous tankyrase inhibitor and a potent inhibitor of PARP1 in vitro and in cells, whereas IWR1 and AZ-6102 are tankyrase selective. Our biochemical and structural analysis of PARP inhibitor potencies establishes a molecular basis for either selectivity or promiscuity and provides a benchmark for experimental design in assessment of PARP inhibitor effects.

Topics: Animals; Benzimidazoles; Enzyme Inhibitors; HEK293 Cells; Humans; Indazoles; Models, Molecular; Phenanthrenes; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Tankyrases

The PARP inhibitor AZD2461 was developed as a next-generation agent following olaparib, the first PARP inhibitor approved for cancer therapy. In BRCA1-deficient mouse models, olaparib resistance predominantly involves overexpression of P-glycoprotein, so AZD2461 was developed as a poor substrate for drug transporters. Here we demonstrate the efficacy of this compound against olaparib-resistant tumors that overexpress P-glycoprotein. In addition, AZD2461 was better tolerated in combination with chemotherapy than olaparib in mice, which suggests that AZD2461 could have significant advantages over olaparib in the clinic. However, this superior toxicity profile did not extend to rats. Investigations of this difference revealed a differential PARP3 inhibitory activity for each compound and a higher level of PARP3 expression in bone marrow cells from mice as compared with rats and humans. Our findings have implications for the use of mouse models to assess bone marrow toxicity for DNA-damaging agents and inhibitors of the DNA damage response. Finally, structural modeling of the PARP3-active site with different PARP inhibitors also highlights the potential to develop compounds with different PARP family member specificity profiles for optimal antitumor activity and tolerability. Cancer Res; 76(20); 6084-94. ©2016 AACR.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Bone Marrow; Cell Line, Tumor; Dacarbazine; DNA Damage; DNA Repair; Drug Discovery; Genes, BRCA1; Humans; Mice; Neoplasms, Experimental; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Rats; Temozolomide; Xenograft Model Antitumor Assays

BRCA1/2-mutant cells are hypersensitive to inactivation of poly(ADP-ribose) polymerase 1 (PARP-1). We recently showed that inhibition of PARP-1 by NU1025 is strongly cytotoxic for BRCA1-positive BT-20 cells, but not BRCA1-deficient SKBr-3 cells. These results raised the possibility that other PARP-1 inhibitors, particularly those tested in clinical trials, may be more efficacious against BRCA1-deficient SKBr-3 breast cancer cells than NU1025. Thus, in the presented study the cytotoxicity of four PARP inhibitors under clinical evaluation (olaparib, rucaparib, iniparib and AZD2461) was examined and compared to that of NU1025. The sensitivity of breast cancer cells to the PARP-1 inhibition strongly varied. Remarkably, BRCA-1-deficient SKBr-3 cells were almost completely insensitive to NU1025, olaparib and rucaparib, whereas BRCA1-expressing BT-20 cells were strongly affected by NU1025 even at low doses. In contrast, iniparib and AZD2461 were cytotoxic for both BT-20 and SKBr-3 cells. Of the four tested PARP-1 inhibitors only AZD2461 strongly affected cell cycle progression. Interestingly, the anti-proliferative and pro-apoptotic potential of the tested PARP-1 inhibitors clearly correlated with their capacity to damage DNA. Further analyses revealed that proteomic signatures of the two studied breast cancer cell lines strongly differ, and a set of 197 proteins was differentially expressed in NU1025-treated BT-20 cancer cells. These results indicate that BT-20 cells may harbor an unknown defect in DNA repair pathway(s) rendering them sensitive to PARP-1 inhibition. They also imply that therapeutic applicability of PARP-1 inhibitors is not limited to BRCA mutation carriers but can be extended to patients harboring deficiencies in other components of the pathway(s).

Topics: Apoptosis; Benzamides; BRCA1 Protein; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Humans; Indoles; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Quinazolines

Poly(ADP-ribose) polymerases (PARP1, -2, and -3) play important roles in DNA damage repair. As such, a number of PARP inhibitors are undergoing clinical development as anticancer therapies, particularly in tumors with DNA repair deficits and in combination with DNA-damaging agents. Preclinical evidence indicates that PARP inhibitors potentiate the cytotoxicity of DNA alkylating agents. It has been proposed that a major mechanism underlying this activity is the allosteric trapping of PARP1 at DNA single-strand breaks during base excision repair; however, direct evidence of allostery has not been reported. Here the data reveal that veliparib, olaparib, niraparib, and talazoparib (BMN-673) potentiate the cytotoxicity of alkylating agents. Consistent with this, all four drugs possess PARP1 trapping activity. Using biochemical and cellular approaches, we directly probe the trapping mechanism for an allosteric component. These studies indicate that trapping is due to catalytic inhibition and not allostery. The potency of PARP inhibitors with respect to trapping and catalytic inhibition is linearly correlated in biochemical systems but is nonlinear in cells. High-content imaging of γH2Ax levels suggests that this is attributable to differential potentiation of DNA damage in cells. Trapping potency is inversely correlated with tolerability when PARP inhibitors are combined with temozolomide in mouse xenograft studies. As a result, PARP inhibitors with dramatically different trapping potencies elicit comparable in vivo efficacy at maximum tolerated doses. Finally, the impact of trapping on tolerability and efficacy is likely to be context specific.. Understanding the context-specific relationships of trapping and catalytic inhibition with both tolerability and efficacy will aid in determining the suitability of a PARP inhibitor for inclusion in a particular clinical regimen.

Topics: Animals; Antineoplastic Agents, Alkylating; Benzimidazoles; Cell Line; Cell Line, Tumor; DNA Damage; DNA Repair; DNA-Binding Proteins; Drug Tolerance; Humans; Indazoles; Mice; Neoplasms, Experimental; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases

Pediatric high-grade astrocytomas (pHGA) and diffuse intrinsic pontine gliomas (DIPG) are devastating malignancies for which no effective therapies exist. We investigated the therapeutic potential of PARP1 inhibition in preclinical models of pHGA and DIPG. PARP1 levels were characterized in pHGA and DIPG patient samples and tumor-derived cell lines. The effects of PARP inhibitors veliparib, olaparib, and niraparib as monotherapy or as radiosensitizers on cell viability, DNA damage, and PARP1 activity were evaluated in a panel of pHGA and DIPG cell lines. Survival benefit of niraparib was examined in an orthotopic xenograft model of pHGA. About 85% of pHGAs and 76% of DIPG tissue microarray samples expressed PARP1. Six of 8 primary cell lines highly expressed PARP1. Interestingly, across multiple cell lines, some PARP1 protein expression was required for response to PARP inhibition; however, there was no correlation between protein level or PARP1 activity and sensitivity to PARP inhibitors. Niraparib was the most effective at reducing cell viability and proliferation (MTT and Ki67). Niraparib induced DNA damage (γH2AX foci) and induced growth arrest. Pretreatment of pHGA cells with a sublethal dose of niraparib (1 μmol/L) before 2 Gy of ionizing radiation (IR) decreased the rate of DNA damage repair, colony growth, and relative cell number. Niraparib (50 mg/kg) inhibited PARP1 activity in vivo and extended survival of mice with orthotopic pHGA xenografts, when administered before IR (20 Gy, fractionated), relative to control mice (40 vs. 25 days). Our data provide in vitro and in vivo evidence that niraparib may be an effective radiosensitizer for pHGA and DIPG.

Topics: Animals; Astrocytoma; Benzimidazoles; Blotting, Western; Brain Stem Neoplasms; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Child; Combined Modality Therapy; Glioma; Humans; Indazoles; Kaplan-Meier Estimate; Linear Models; Mice, Inbred NOD; Mice, Knockout; Mice, SCID; Microscopy, Confocal; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Pons; Radiotherapy; Xenograft Model Antitumor Assays

Hydrogen and deuterium gas were produced and directly applied in a two-chamber system. These gaseous reagents were generated by the simple reaction of metallic zinc with HCl in water for H2 and DCl in deuterated water for D2. The setup proved efficient in classical Pd-catalyzed reductions of ketones, alkynes, alkenes, etc. in near-quantitative yields. The method was extended to the synthesis and isotope labeling of quinoline and 1,2,3,4-tetrahydroquinoline derivatives. Finally, CX-546 and Olaparib underwent efficient Ir-catalyzed hydrogen isotope exchange reactions.

Topics: Alkenes; Alkynes; Catalysis; Deuterium; Dioxanes; Dioxoles; Hydrogen; Isotope Labeling; Kinetics; Metals; Oxidation-Reduction; Phthalazines; Piperazines; Piperidines; Quinolines

Lymphangioleiomyomatosis (LAM) is a female-predominant cystic lung disease that can lead to respiratory failure. LAM cells typically have inactivating tuberous sclerosis complex 2 (TSC2) mutations and mammalian target of rapamycin (mTOR) complex (mTORC) 1 activation. Clinical response to the mTORC1 inhibitors has been limited, prompting a search for additional therapy for LAM. In this study, we investigated the impact of TSC2 on the expression of poly (ADP-ribose) polymerase (PARP)-1 that initiates the DNA repair pathway, and tested the efficacy of PARP1 inhibitors in the survival of TSC2-deficient (TSC2(-)) cells. We analyzed publicly available expression arrays of TSC2(-) cells and validated the findings using real-time RT-PCR, immunoblotting, and immunohistochemistry. We examined the impact of rapamycin and Torin 1 on PARP1 expression. We also tested the effect of PARP1 inhibitors, 8-hydroxy-2-methylquinazoline-4-one and 3,4-dihydro-5[4-(1-piperindinyl)butoxy]-1(2H)-isoquinoline, on the survival of TSC2(-) cells. We identified the up-regulation of PARP1 in TSC2(-) cells relative to cells in which wild-type TSC2 has been reintroduced (TSC2-addback [TSC2(+)] cells). The transcript levels of PARP1 in TSC2(-) cells were not affected by rapamycin. PARP1 levels were increased in TSC2(-) cells, xenograft tumors of rat-derived TSC2(-) cells, renal cystadenomas from Tsc2(+/-) mice, and human LAM nodules. RNA interference of mTOR failed to reduce PARP1 levels. Proliferation and survival of TSC2(-) cells was reduced in response to PARP1 inhibitor treatment, more so than TSC2(+) cells. TSC2(-) cells exhibit higher levels of PARP1 relative to TSC2(+) cells in an mTOR-insensitive manner. PARP1 inhibitors selectively suppress the growth and induce apoptosis of TSC2(-) cells from patients with LAM. Targeting PARP1 may be beneficial in the treatment of LAM and other neoplasm with mTORC1 activation.

Topics: Animals; Antineoplastic Agents; Cell Line; DNA Repair; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Enzymologic; Humans; Isoquinolines; Lung Neoplasms; Lymphangioleiomyomatosis; Mice, Inbred C57BL; Mice, SCID; Molecular Targeted Therapy; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Quinazolines; Rats; Sirolimus; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins; Up-Regulation; Xenograft Model Antitumor Assays

Excision repair cross-complementation group 1 (ERCC1) is a DNA repair enzyme that is frequently defective in non-small cell lung cancer (NSCLC). Although low ERCC1 expression correlates with platinum sensitivity, the clinical effectiveness of platinum therapy is limited, highlighting the need for alternative treatment strategies. To discover new mechanism-based therapeutic strategies for ERCC1-defective tumours, we performed high-throughput drug screens in an isogenic NSCLC model of ERCC1 deficiency and dissected the mechanism underlying ERCC1-selective effects by studying molecular biomarkers of tumour cell response. The high-throughput screens identified multiple clinical poly (ADP-ribose) polymerase 1 and 2 (PARP1/2) inhibitors, such as olaparib (AZD-2281), niraparib (MK-4827) and BMN 673, as being selective for ERCC1 deficiency. We observed that ERCC1-deficient cells displayed a significant delay in double-strand break repair associated with a profound and prolonged G₂/M arrest following PARP1/2 inhibitor treatment. Importantly, we found that ERCC1 isoform 202, which has recently been shown to mediate platinum sensitivity, also modulated PARP1/2 sensitivity. A PARP1/2 inhibitor-synthetic lethal siRNA screen revealed that ERCC1 deficiency was epistatic with homologous recombination deficiency. However, ERCC1-deficient cells did not display a defect in RAD51 foci formation, suggesting that ERCC1 might be required to process PARP1/2 inhibitor-induced DNA lesions before DNA strand invasion. PARP1 silencing restored PARP1/2 inhibitor resistance in ERCC1-deficient cells but had no effect in ERCC1-proficient cells, supporting the hypothesis that PARP1 might be required for the ERCC1 selectivity of PARP1/2 inhibitors. This study suggests that PARP1/2 inhibitors as a monotherapy could represent a novel therapeutic strategy for NSCLC patients with ERCC1-deficient tumours.

Topics: Antineoplastic Agents; Carcinoma, Non-Small-Cell Lung; Cell Line; Cell Line, Tumor; DNA Breaks, Double-Stranded; DNA Repair; DNA-Binding Proteins; Endonucleases; Enzyme Inhibitors; G2 Phase Cell Cycle Checkpoints; High-Throughput Screening Assays; Humans; Indazoles; Lung Neoplasms; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Protein Isoforms; Rad51 Recombinase; RNA Interference; RNA, Small Interfering

Inhibition of PARP is a promising therapeutic strategy for homologous recombination-deficient tumors, such as BRCA1-associated cancers. We previously reported that BRCA1-deficient mouse mammary tumors may acquire resistance to the clinical PARP inhibitor (PARPi) olaparib through activation of the P-glycoprotein drug efflux transporter. Here, we show that tumor-specific genetic inactivation of P-glycoprotein increases the long-term response of BRCA1-deficient mouse mammary tumors to olaparib, but these tumors eventually developed PARPi resistance. In a fraction of cases, this resistance is caused by partial restoration of homologous recombination due to somatic loss of 53BP1. Importantly, PARPi resistance was minimized by long-term treatment with the novel PARP inhibitor AZD2461, which is a poor P-glycoprotein substrate. Together, our data suggest that restoration of homologous recombination is an important mechanism for PARPi resistance in BRCA1-deficient mammary tumors and that the risk of relapse of BRCA1-deficient tumors can be effectively minimized by using optimized PARP inhibitors.. In this study, we show that loss of 53BP1 causes resistance to PARP inhibition in mouse mammary tumors that are deficient in BRCA1. We hypothesize that low expression or absence of 53BP1 also reduces the response of patients with BRCA1-deficient tumors to PARP inhibitors.

Topics: Animals; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; BRCA1 Protein; Cell Line, Tumor; Chromosomal Proteins, Non-Histone; DNA Damage; DNA-Binding Proteins; Drug Resistance, Neoplasm; Enzyme Inhibitors; Female; Mammary Neoplasms, Animal; Mice; Mutation; Phthalazines; Piperazines; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Tumor Suppressor p53-Binding Protein 1

PARP inhibitors have been proposed as a potential targeted therapy for patients with triple-negative (ER-, PR-, HER2-negative) breast cancers. However, it is as yet unclear as to whether single agent or combination therapy using PARP inhibitors would be most beneficial. To better understand the mechanisms that determine the response to PARP inhibitors, we investigated whether enzymes involved in metabolism of the PARP substrate, β-NAD(+) , might alter the response to a clinical PARP inhibitor. Using an olaparib sensitization screen in a triple-negative (TN) breast cancer model, we identified nicotinamide phosphoribosyltransferase (NAMPT) as a non-redundant modifier of olaparib response. NAMPT is a rate-limiting enzyme involved in the generation of the PARP substrate β-NAD(+) and the suppression of β-NAD(+) levels by NAMPT inhibition most likely explains these observations. Importantly, the combination of a NAMPT small molecule inhibitor, FK866, with olaparib inhibited TN breast tumour growth in vivo to a greater extent than either single agent alone suggesting that assessing NAMPT/PARP inhibitor combinations for the treatment of TN breast cancer may be warranted.

Topics: Acrylamides; Animals; Breast Neoplasms; Cell Line, Tumor; Cytokines; Female; Humans; Mice; Mice, Nude; Nicotinamide Phosphoribosyltransferase; Phthalazines; Piperazines; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Transplantation, Heterologous