pyrimidinones and olaparib

Despite notable advances in utilising PARP inhibitor monotherapy, many cancers are not PARP inhibitor-sensitive or develop treatment resistance. In this work, we show that the two structurally-related sesquiterpene lactones, a 2-bromobenzyloxy derivative of dehydrosantonin (BdS) and alantolactone (ATL) sensitise p53 wildtype, homologous recombination-proficient cancer cells to low-dose treatment with the PARP inhibitor, olaparib. Exposure to combination treatments of olaparib with BdS or ATL induces cell-cycle changes, chromosomal instability, as well as considerable increases in nuclear area. Mechanistically, we uncover that mitotic errors likely depend on oxidative stress elicited by the electrophilic lactone warheads and olaparib-mediated PARP-trapping, culminating in replication stress. Combination treatments exhibit moderately synergistic effects on cell survival, probably attenuated by a p53-mediated, protective cell-cycle arrest in the G2 cell-cycle phase. Indeed, using a WEE1 inhibitor, AZD1775, to inhibit the G2/M cell-cycle checkpoint further decreased cell survival. Around half of all cancers diagnosed retain p53 functionality, and this proportion could be expected to increase with improved diagnostic approaches in the clinic. Utilising sublethal oxidative stress to sensitise p53 wildtype, homologous recombination-proficient cancer cells to low-dose PARP-trapping could therefore serve as the basis for future research into the treatment of cancers currently refractory to PARP inhibition.

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Chromosomal Instability; Dose-Response Relationship, Drug; Drug Synergism; Humans; Lactones; Neoplasms; Oxidative Stress; Phthalazines; Piperazines; Pyrazoles; Pyrimidinones; Sesquiterpenes; Sesquiterpenes, Eudesmane; Tumor Suppressor Protein p53

Chemotherapy is a standard regimen for advanced or relapsed biliary tract cancer (BTC) with a 5-year overall survival (OS) rate of approximately 5% and a median OS of less than a year. Targeted therapies and immunotherapy aimed at providing more personalized treatments for BTCs have been tested. The objective of this study was to evaluate the effects of targeted therapy and immunotherapy on advanced BTC patients.. Twenty-four advanced/relapsed BTC patients were enrolled and examined with next-generation sequencing (NGS). Eight of them received NGS-guided targeted or immunotherapy, and the other 16 patients underwent routine chemotherapy. Comparison analysis of OS and objective response rate (ORR) was performed.. IDH1, BRCA2, MAP2K1, and BRAF (V600E) were the major actionable genes mutated in this cohort. Patients who received NGS-guided therapy exhibited higher OS (not achieved vs. 6.5 months, p < 0.001) and ORR (87.5% vs. 25%, p < 0.001) than those without targetable mutations and who received first-line chemotherapy. BTCs harboring mutations in IDH1, ATM/BRCA2, or MAP2K1/BRAF (V600E) received treatment with dasatinib, olaparib, or trametinib, respectively. Three of the patients had high tumor mutation burden (TMB-H) and were treated with immune-checkpoint inhibitors and chemotherapy. All these patients achieved complete response or partial response.. NGS-guided targeted therapy and immunotherapy are promising personalized therapies for advanced or relapsed BTCs. TMB is a useful biomarker for predicting immunotherapy efficacy.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Biliary Tract Neoplasms; Biomarkers, Tumor; Combined Modality Therapy; Dasatinib; Female; Follow-Up Studies; High-Throughput Nucleotide Sequencing; Humans; Immunotherapy; Male; Middle Aged; Molecular Targeted Therapy; Neoplasm Recurrence, Local; Phthalazines; Piperazines; Prognosis; Prospective Studies; Pyridones; Pyrimidinones; Survival Rate

The G1/S cell cycle checkpoint is frequently dysregulated in cancer, leaving cancer cells reliant on a functional G2/M checkpoint to prevent excessive DNA damage. Wee1 regulates the G2/M checkpoint by phosphorylating CDK1 at Tyr15 to prevent mitotic entry. Previous drug development efforts targeting Wee1 resulted in the clinical-grade inhibitor, AZD1775. However, AZD1775 is burdened by dose-limiting adverse events, and has off-target PLK1 activity. In an attempt to overcome these limitations, we developed Wee1 degraders by conjugating AZD1775 to the cereblon (CRBN)-binding ligand, pomalidomide. The resulting lead compound, ZNL-02-096, degrades Wee1 while sparing PLK1, induces G2/M accumulation at 10-fold lower doses than AZD1775, and synergizes with Olaparib in ovarian cancer cells. We demonstrate that ZNL-02-096 has CRBN-dependent pharmacology that is distinct from AZD1775, which justifies further evaluation of selective Wee1 degraders.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Proteins; Cell Line, Tumor; DNA Damage; Drug Development; Female; Humans; Molecular Structure; Phthalazines; Piperazines; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Proteolysis; Pyrazoles; Pyrimidinones; Thalidomide

Due to its regulation of CDK1/2 phosphorylation, WEE1 plays essentially roles in the regulations of G2/M checkpoint and DNA damage response (DDR). WEE1 inhibition can increase genomic instability by inducing replication stress and G2/M checkpoint inactivation, which result in increased cellular sensitivity to DNA damaging agents. We considered an increase in genomic instability induced by WEE1 inhibition might be used to augment the effects of drugs targeting DNA repair protein. Typically, PARP inhibitors are effective in germline BRCA 1/2 mutated breast and ovarian cancer, but their applicabilities in triple-negative breast cancer (TNBC) are limited. This study was conducted to investigate the anti-tumor effects of the WEE1 inhibitor, AZD1775, and the mechanism responsible for its potentiation of sensitivity to olaparib (a PARP inhibitor) via the modulation of DDR in TNBC cells. Our results suggest that AZD1775 could be used to broaden the application range of olaparib in TNBC and provide a rationale for a clinical trial of combined olaparib and AZD1775 therapy.

Topics: Animals; Apoptosis; Cell Cycle; Cell Cycle Proteins; Cell Proliferation; DNA Damage; DNA Repair; Drug Resistance, Neoplasm; Drug Synergism; Enzyme Inhibitors; Female; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidinones; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

KRAS mutations in non-small cell lung cancer (NSCLC) cause increased levels of DNA damage and replication stress, suggesting that inhibition of the DNA damage response (DDR) is a promising strategy for radiosensitization of NSCLC. This study investigates the ability of a WEE1 inhibitor (AZD1775) and a PARP inhibitor (olaparib) to radiosensitize KRAS-mutant NSCLC cells and tumors. In addition to inhibiting the DDR, these small-molecule inhibitors of WEE1 and PARP induce DNA replication stress via nucleotide exhaustion and PARP trapping, respectively. As monotherapy, AZD1775 or olaparib alone modestly radiosensitized a panel of KRAS-mutant NSCLC lines. The combination of agents, however, significantly increased radiosensitization. Furthermore, AZD1775-mediated radiosensitization was rescued by nucleotide repletion, suggesting a mechanism involving AZD1775-mediated replication stress. In contrast, radiosensitization by the combination of AZD1775 and olaparib was not rescued by nucleosides. Whereas both veliparib, a PARP inhibitor that does not efficiently trap PARP1 to chromatin, and PARP1 depletion radiosensitized NSCLC cells as effectively as olaparib, which does efficiently trap PARP, only olaparib potentiated AZD1775-mediated radiosensitization. Taken together, these mechanistic data demonstrate that although nucleotide depletion is sufficient for radiosensitization by WEE1 inhibition alone, and inhibition of PARP catalytic activity is sufficient for radiosensitization by olaparib alone, PARP1 trapping is required for enhanced radiosensitization by the combination of WEE1 and PARP inhibitors.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cell Survival; DNA Replication; Drug Synergism; Humans; Lung Neoplasms; Mice; Mutation; Phthalazines; Piperazines; Poly (ADP-Ribose) Polymerase-1; Proto-Oncogene Proteins p21(ras); Pyrazoles; Pyrimidines; Pyrimidinones; Radiation-Sensitizing Agents; Xenograft Model Antitumor Assays

Targeting poly ADP-ribose polymerase (PARP) has been recently identified as a promising option against gastric cancer (GC). However, PARP inhibitors alone achieve limited efficacy. Combination strategies, especially with homologous recombination (HR) impairment, are of great hope to optimize PARP inhibitor's efficacy and expand target populations but remains largely unknown. Herein, we investigated whether a WEE1/ Polo-like kinase 1 (PLK1) dual inhibitor AZD1775 reported to impair HR augmented anticancer activity of a PARP inhibitor olaparib and its underlying mechanisms.. GC cell lines and in vivo xenografts were employed to determine antitumor activity of PARP inhibitor combined with WEE1/PLK1 dual inhibitor AZD1775. Western blot, genetic knockdown by siRNA, flow cytometry, Immunohistochemistry were performed to explore the underlying mechanisms.. AZD1775 dually targeting WEE1/PLK1 enhanced effects of olaparib on growth inhibition and apoptotic induction in GC cells. Mechanistic investigations elucidate that WEE1/PLK1 blockade downregulated several HR-related proteins and caused an accumulation in γH2AX. As confirmed in both GC cell lines and mice bearing GC xenografts, these effects were enhanced by AZD1775-olaparib combination compared to olaparib alone, suggesting that disrupting HR-mediated DNA damage repairs (DDR) by WEE1/PLK1 blockade might be responsible for improved GC cells' response to PARP inhibitors. Given the DNA damage checkpoint as a primary target of WEE1 inhibition, our data also demonstrate that AZD1775 abrogated olaparib-activated DNA damage checkpoint through CDC2 de-phosphorylation, followed by mitotic progression with unrepaired DNA damage (marked by increased pHH3-stained and γH2AX-stained cells, respectively).. PARP inhibitor olaparib combined with WEE1/PLK1 dual inhibitor AZD1775 elicited potentiated anticancer activity through disrupting DDR signaling and the DNA damage checkpoint. It sheds light on the combination strategy of WEE1/PLK1 dual inhibitors with PARP inhibitors in the treatment of GC, even in HR-proficient patients.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; DNA Damage; DNA Repair; Drug Synergism; Female; Humans; Mice; Nuclear Proteins; Phthalazines; Piperazines; Polo-Like Kinase 1; Poly(ADP-ribose) Polymerase Inhibitors; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Pyrazoles; Pyrimidines; Pyrimidinones; Stomach Neoplasms; Xenograft Model Antitumor Assays

Although some patients with acute leukemia have good prognoses, the prognosis of adult and pediatric patients who relapse or cannot tolerate standard chemotherapy is poor. Inhibition of WEE1 with AZD1775 has been shown to sensitize cancer cells to genotoxic chemotherapies, including cytarabine in acute myeloid leukemia (AML) and T-ALL. Inhibition of WEE1 impairs homologous recombination by indirectly inhibiting BRCA2. Thus, we sought to determine whether AZD1775 could sensitize cells to the PARP1/2 inhibitor olaparib. We found that combined treatment with AZD1775 and olaparib was synergistic in AML and ALL cells, and this combination impaired proliferative capacity upon drug withdrawal. AZD1775 impaired homologous recombination in olaparib-treated cells, resulting in enhanced DNA damage accumulation and apoptosis induction. This combination enhanced disease control and increased survival in a murine AML model. Furthermore, we demonstrated that combined treatment with AZD1775 and olaparib reduces proliferation and colony formation and increases apoptosis in AML patient samples. In aggregate, these studies raise the possibility of rational combinations of targeted agents for leukemia in patients for whom conventional chemotherapeutics may not be effective or well tolerated.

Topics: Animals; Apoptosis; Cell Line, Tumor; Cell Proliferation; DNA Damage; Humans; Leukemia, Myeloid, Acute; Mice; Phthalazines; Piperazines; Pyrazoles; Pyrimidines; Pyrimidinones; Recombinational DNA Repair; Xenograft Model Antitumor Assays

The poly(ADP-ribose) polymerase (PARP) family represents a new class of therapeutic targets with diverse potential disease indications. PARP1 and PARP2 inhibitors have been developed for breast and ovarian tumors manifesting double-stranded DNA-repair defects, whereas tankyrase 1 and 2 (TNKS1 and TNKS2, also known as PARP5a and PARP5b, respectively) inhibitors have been developed for tumors with elevated β-catenin activity. As the clinical relevance of PARP inhibitors continues to be actively explored, there is heightened interest in the design of selective inhibitors based on the detailed structural features of how small-molecule inhibitors bind to each of the PARP family members. Here, the high-resolution crystal structures of the human TNKS2 PARP domain in complex with 16 various PARP inhibitors are reported, including the compounds BSI-201, AZD-2281 and ABT-888, which are currently in Phase 2 or 3 clinical trials. These structures provide insight into the inhibitor-binding modes for the tankyrase PARP domain and valuable information to guide the rational design of future tankyrase-specific inhibitors.

Topics: Benzamides; Benzimidazoles; Bridged Bicyclo Compounds, Heterocyclic; Catalytic Domain; Crystallography, X-Ray; Enzyme Inhibitors; Humans; Models, Molecular; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Protein Conformation; Pyrimidinones; Quinazolines; Tankyrases