ART558 / Artios Pharma - LARVOL DELTA

Cyclin D1 Overexpression in Mantle Cell Lymphoma Causes Cellular Dependence on Microhomology-Mediated End-Joining (ASH 2024) - "As expected, genetic deletion or pharmacological inhibition (ART558 and novobiocin) of POLQ in MCL cells led to increased RS and increased unrepaired DNA damage during mitosis, ultimately leading to chromosomal instability, mitotic catastrophe, and apoptosis...When POLQ was inhibited, a significant antitumor effect was evident in MCL cells, including ibrutinib-resistant MCL, both in vitro and in vivo, and this effect was enhanced by ATM deficiency. Further, simultaneous inhibition of both ATM (AZD0156) and POLQ was synthetic lethal in MCL cell lines and primary tumor cells from patients with MCL...Within MCL, POLQ is crucial in mitigating the adversities of CCND1-driven RS. Our data suggest that targeting the MMEJ pathway via POLQ inhibition, particularly in the presence of CCND1 overexpression and ATM deficiency, emerges as a promising therapeutic approach in oncoprotein-driven hematologic malignancies such as MCL."

Hematological Disorders • Hematological Malignancies • Lymphoma • Mantle Cell Lymphoma • Non-Hodgkin’s Lymphoma • Oncology • ATM • CCND1 • HRD • POLQ

DNA-PKcs inhibition improves sequential gene insertion of the full-length CFTR cDNA in airway stem cells. (PubMed, Mol Ther Nucleic Acids) - "To improve CFTR cDNA insertion in human airway basal stem cells (ABCs), we evaluated the use of the small molecules AZD7648 and ART558, which inhibit non-homologous end-joining (NHEJ) and micro-homology mediated end-joining (MMEJ). Adding AZD7648 did not increase off-target editing. Further studies are necessary to validate if AZD7648 treatment enriches cells with oncogenic mutations."

Journal • Cystic Fibrosis • Genetic Disorders • Immunology • Oncology • Pulmonary Disease • Respiratory Diseases • CFTR

Polθ Inhibitor (ART558) Demonstrates a Synthetic Lethal Effect with PARP and RAD52 Inhibitors in Glioblastoma Cells. (PubMed, Int J Mol Sci) - "In our studies we hypothesized that inhibition of DNA polymerase theta (Polθ) and its combination with Poly (ADP-ribose) polymerase 1 (PARP1) or RAD52 inhibition and the alkylating drug temozolomide (TMZ) has an anticancer effect on glioblastoma cells (GBM21), whereas it has a low impact on normal human astrocytes (NHA). The impact on normal cells is much lower, especially when considering cell viability and DNA damage. In conclusion, we would like to highlight that Polθ inhibition used in combination with PARP1 or RAD52 inhibition has great potential to kill glioblastoma cells, and shows a synthetic lethal effect, while sparing normal astrocytes."

Journal • Synthetic lethality • Brain Cancer • CNS Tumor • Glioblastoma • Oncology • Solid Tumor • POLQ • RAD52

DNA-PKcs Inhibition Improves Sequential Gene Insertion of the Full-Length CFTR cDNA in Airway Stem Cells. (PubMed, bioRxiv) - "To improve CFTR cDNA insertion in human airway basal stem cells (ABCs), we evaluated the use of the small molecules AZD7648 and ART558 which inhibit non-homologous end joining (NHEJ) and micro-homology mediated end joining (MMEJ). Adding AZD7648 did not increase off-target editing. Further studies are necessary to validate if AZD7648 treatment enriches cells with oncogenic mutations."

Journal • Cystic Fibrosis • Genetic Disorders • Immunology • Oncology • Pulmonary Disease • Respiratory Diseases • CFTR

Talazoparib enhances resection at DSBs and renders HR-proficient cancer cells susceptible to Polθ inhibition. (PubMed, Radiother Oncol) - "We propose that talazoparib promotes low-dose, CtIP/MRE11-dependent resection and increases the reliance of irradiated HR-proficient cancer cells, on Polθ-mediated alt-EJ. Combination of Polθ inhibitors with talazoparib suppresses this option and causes further radiosensitization. The results suggest that Polθ inhibition may be exploited to maximize talazoparib radiosensitization of HR-proficient tumors in the clinic."

Journal • Oncology • MRE11A • POLQ

Overexpression of human DNA polymerase theta is a biomarker of aggressive and DNA repair-deficient papillary thyroid cancers. (PubMed, Surgery) - "These findings suggest that increased POLQ expression could serve as a valuable clinical marker and a potential therapeutic target in the treatment of thyroid cancer."

Biomarker • Journal • Endocrine Cancer • Oncology • Solid Tumor • Thyroid Gland Carcinoma • Thyroid Gland Papillary Carcinoma • BRAF • POLQ

Repurposed DNA Repair Inhibitors to Enhance Targeted Integration Drastically Increases Chromosomal Instability (ASGCT 2024) - "To explore this, we cultured CRISPR-Cas9 edited haematopoietic stem and progenitor cells (HSPCs) with an end-joining repair inhibitor cocktail (ART558 and AZD7648) and performed CAST-Seq and digital PCR (dPCR) to quantify aberrations. Seeking to adopt repair-inhibiting compounds may improve integration efficacy but at the cost of genome destabilisation and increasing the risk of generating genotoxic by-products. We propose that repairinhibiting compounds may be better suited as sensitivityenhancing agents to improve the resolution of existing offtarget and aberration-detecting techniques."

Late-breaking abstract • Gene Therapies

Synergistic combinations and tissue type-specificity of compounds targeting components of the DNA damage response pathway in 2D culture and 3D spheroid cell viability assays (AACR 2024) - "In 2D cell viability assays, PARP inhibitors and the Polθ inhibitor ART558 were more active in BRCA2-deficient compared to BRCA2-proficient DLD-1 cells, whereas an ATR inhibitor (ceralasertib) was equally potent in both cell lines...Moreover, olaparib synergized with ceralasertib in both BRCA2-deficient and -proficient DLD-1 cells...Res. 10, 112-22; 2018"

Colon Cancer • Colorectal Adenocarcinoma • Gastrointestinal Cancer • Oncology • Ovarian Cancer • Solid Tumor • BRCA2

Activity of PARP1-selective inhibitor SNV-001 in models of HRD cancers as monotherapy and in combination (AACR 2024) - "SNV-001 showed greater efficacy at lower doses compared to olaparib at 100 mg/kg or at equivalent doses of AZD9574...SNV-001 enhanced cytotoxicity of the DNA-damaging agent topotecan or carboplatin in Capan-1 (BRCA2mut) and HCC1395 (BRCA1mut) cells. Synergy was seen between SNV-001 and cell cycle check point inhibitors camonsertib (ATRi) or adavosertib (WEE1i) in DLD1 (BRCA2 -/-) and UWB1.289 (BRCA1mut) cells, as DNA damage induced by PARP1 trapping relies on cell cycle modulation for repair. Combination of SNV-001 with polymerase theta inhibitor ART558 or USP1 inhibitor KSQ4279 exhibited synergistic effects in DLD1 (BRCA2 -/-) or UWB1.289 (BRCA1mut) cells...Current data highlight a potential strategy for improving treatment efficacy and overcoming resistance. Further clinical investigations are warranted to validate this combination strategy."

Monotherapy • Oncology • BRCA1 • BRCA2 • HRD • PARP2 • USP1

Polymerase θ (POLθ) inhibitors (novobiocin, ART-558, RP6685) were tested with 22 approved and investigational agents in multi-cell type spheroids of genetically selected patient-derived human tumor cell lines (AACR 2024) - "The potential of novobiocin to augment cancer chemotherapy was explored in the late 1980s and early 1990s in tumor cells and tumor-bearing mice and in Phase 1 clinical trials with cyclophosphamide or cisplatin...Potentiation of the topoisomerase II inhibitors doxorubicin (DOX) and etoposide by the POLθ inhibitors ART-558 or RP6685 was observed in spheroids grown from the serous endometrial adenocarcinoma 922993-354-T-J3, which has ATM and BRCA2 variants...Activity of the Chk1/2 inhibitor prexasertib was potentiated by either ART-558 or RP6685 in the 922993-354-T-J3 complex spheroids...KRAS G12D inhibitor MRTX-133 cytotoxicity against 186277-243-T-J2 colon adenocarcinoma with the KRAS G12D variant was potentiated by either ART-558 or RP6685. Potential combinations to advance into in vivo studies will be presented."

Late-breaking abstract • Preclinical • Tumor cell • Colon Cancer • Colorectal Adenocarcinoma • Colorectal Cancer • Endometrial Adenocarcinoma • Endometrial Cancer • Gastrointestinal Cancer • Oncology • Solid Tumor • BRCA • BRCA2 • KRAS • LIG3 • PALB2 • POLQ • XRCC1

Divergent Functions of ERK2 Substrate Binding Modalities in Myeloproliferative Neoplasm (ASH 2023) - "Lin-CD34+ MPN HSPC were more sensitive to Polq inhibitor, ART558, compared to normal implicating Polq as a therapeutic target in MPNs... The findings suggest that a combination therapy, such as Polqi + ERK2-Di, may be a promising strategy to overcome treatment resistance arising from clonal variations in sensitivity to single agents. By targeting both the D domain and inhibiting the downstream substrate Polq, a synergistic anti-MPN effect may be achieved, potentially offering a more effective therapeutic approach for patients with MPNs."

Acute Myelogenous Leukemia • Hematological Disorders • Hematological Malignancies • Myeloproliferative Neoplasm • Oncology • Targeted Protein Degradation • Transplantation • CALR • CD34 • EGR1 • MAPK1 • NRAS • POLQ • WT1

Mechanisms of synthetic lethality between BRCA1/2 and 53BP1 deficiencies and DNA polymerase theta targeting. (PubMed, Nat Commun) - "Firstly, we find that the sensitivity of BRCA1/2- and 53BP1-deficient cells to Polθ loss, and 53BP1-deficient cells to Polθ inhibition (ART558) requires RAD52, and appropriate reduction of RAD52 can ameliorate these phenotypes...In contrast, the survival of BRCA1-deficient cells treated with Polθ inhibitor are not restored by RAD52 suppression, and ssDNA gap-filling is prevented by the chemically inhibited polymerase itself. These data define an additional role for Polθ, reveal the mechanism underlying synthetic lethality between 53BP1, BRCA1/2 and Polθ loss, and indicate genotype-dependent Polθ inhibitor mechanisms."

Journal • Synthetic lethality • BRCA1 • BRCA2 • MRE11A • POLQ • RAD52 • TP53BP1

Insertion of the CFTR cDNA in the CFTR locus in human bronchial epithelial cells is improved by inhibiting the nonhomologous end joining DNA repair pathway (NACFC 2023) - " NHEJ and MMEJ were inhibited using small molecules AZD7648 (PKi) and ART558 (PolΘi), respectively (Figure 1A). Inhibiting NHEJ using PKi is most effective in increasing cell yield using the universal strategy. Inhibition of MMEJ using PolΘi does not further increase cell yield."

CFTR

Robust Radiosensitization by Combined Treatment of Cancer Cells with Talazoparib and Polθ Inhibitors. (PubMed, Int J Radiat Oncol Biol Phys) - "Talazoparib increases the reliance of irradiated cancer cells on Polθ-mediated alt-EJ owing to the increased CtIP/MRE11-dependent resection it produces. Combining talazoparib with Polθ inhibitors has therefore great potential in improving radiotherapy of human tumors."

Journal • Oncology • DNA2 • MRE11A • POLQ

Robust Radiosensitization by Combined Treatment of Cancer Cells with Talazoparib and Pol? Inhibitors (ASTRO 2023) - "inhibitors ART558/novobiocin prior to irradiation...inhibition had a much lower effect (by ~7-17%) when combined with other clinically used PARP inhibitors, olaparib, rucaparib, and veliparib... Talazoparib increases the reliance of irradiated cancer cells on Pol?-mediated alt-EJ owing to the increased CtIP/MRE11-dependent resection it produces. Combining talazoparib with Pol? inhibitors has therefore great potential in improving radiotherapy of human tumors."

Oncology • MRE11A • POLQ

Inhibition of p300 Increases Cytotoxicity of Cisplatin in Pancreatic Cancer Cells. (PubMed, Gene) - "We then determine the extent that two DNA repair inhibitors (CCS1477, a small molecule inhibitor of p300, and ART558, a small molecule inhibitor of polymerase theta) can exploit this repair deficiency to make pancreatic cancer cells more sensitive to cisplatin, a commonly used genotoxic chemotherapeutic. The increased toxicity was not seen in a non-transformed pancreatic cell line. We also found that while ART558 sensitizes pancreatic cancer cells to cisplatin, it also sensitized non-transformed pancreatic cancer cells."

Journal • Gastrointestinal Cancer • Hepatology • Oncology • Pancreatic Cancer • Solid Tumor

Targeting DNA polymerase theta and ATM leads to synergistic killing of mantle cell lymphoma cells (AACR 2023) - "In vitro, single-agent treatment with novobiocin or ART558 caused a significant cytotoxic effect at physiologically relevant concentrations in ATM-deficient cells and co-treatment of novobiocin or ART558 with AZD0156 was synergistic in killing ATM-proficient MCL cells. Importantly, POLQ inhibitors significantly decreased the cell viability of MCIR1, which is an ibrutinib-resistant MCL cell line... POLQ is a promising target in MCL, especially in ATM-deficient setting. In ATM-proficient MCL, targeting ATM and POLQ is synergistic. Our data has the potential to uncover novel biomarker-driven drug therapy of POLQ inhibitors in R/R MCL."

Hematological Malignancies • Lymphoma • Mantle Cell Lymphoma • Non-Hodgkin’s Lymphoma • Oncology • POLQ

Modulating mutational outcomes and improving precise gene editing at CRISPR-Cas9-induced breaks by chemical inhibition of end-joining pathways. (PubMed, Cell Rep) - "We show robust inhibition of TMEJ activity at CRISPR-Cas9-induced double-strand breaks (DSBs) using ART558, a potent polymerase theta (Polϴ) inhibitor...Finally, we show that combined chemical inhibition of TMEJ and NHEJ increases the efficiency of homology-driven repair (HDR)-mediated precise gene editing. Our work reports a robust strategy to improve the fidelity and safety of genome engineering."

Journal

Small-molecule Polθ inhibitors provide safe and effective tumor radiosensitization in preclinical models. (PubMed, Clin Cancer Res) - "These results pave the way for future clinical trials of Polθ inhibitors in combination with radiotherapy."

Journal • Preclinical • Oncology • POLQ

Discovery, Characterization, and Structure-Based Optimization of Small-Molecule In Vitro and In Vivo Probes for Human DNA Polymerase Theta. (PubMed, J Med Chem) - "As previously reported, we recently identified the first selective small molecule Polθ in vitro probe, 22 (ART558), which recapitulates the phenotype of Polθ loss, and in vivo probe, 43 (ART812), which is efficacious in a model of PARP inhibitor resistant TNBC in vivo...The crystallographic data provides a basis for understanding the unique mechanism of inhibition of these compounds which is dependent on stabilization of a "closed" enzyme conformation. Additionally, the structural biology platform provided a basis for rational optimization based primarily on reduced ligand conformational flexibility."

Journal • Preclinical • Oncology • Triple Negative Breast Cancer • BRCA • POLQ

Targeting PARP inhibitor resistance with Polθ inhibitors (AACR 2022) - "To target DNA repair vulnerabilities in cancer, we discovered nanomolar potent, selective, low molecular weight (MW), allosteric inhibitors of the polymerase function of DNA polymerase Polθ, including ART558...The inhibition of DNA nucleases that promote end-resection, such as Exo1 or Blm-Dna2 reversed these effects, implicating these in the synthetic lethal mechanism-of-action. Taken together, these observations describe a drug class that elicits BRCA-gene synthetic lethality and PARP inhibitor synergy, as well as targeting a biomarker-defined mechanism of PARPi-resistance."

Oncology • BRCA • BRCA1 • BRCA2 • TP53BP1

Polθ inhibitors elicit BRCA-gene synthetic lethality and target PARP inhibitor resistance. (PubMed, Nat Commun) - "Mechanistically, ART558 increases biomarkers of single-stranded DNA and synthetic lethality in 53BP1-defective cells whilst the inhibition of DNA nucleases that promote end-resection reversed these effects, implicating these in the synthetic lethal mechanism-of-action. Taken together, these observations describe a drug class that elicits BRCA-gene synthetic lethality and PARP inhibitor synergy, as well as targeting a biomarker-defined mechanism of PARPi-resistance."

Journal • Synthetic lethality • Oncology • BRCA • BRCA1 • BRCA2 • TP53BP1