Potent Reversible Inhibitor Research Articles

A carrier free delivery system of a MAGL inhibitor is effective on ovarian cancer

Monoacylglycerol lipase (MAGL) is a promising target for cancer therapy due to its involvement in lipid metabolism and its impact on cancer hallmarks like cell proliferation, migration, and tumor progression. A potent reversible MAGL inhibitor, MAGL23, has been recently developed by our group, demonstrating promising anticancer activities. To enhance its pharmacological properties, a nanoformulation using nanocrystals coated with albumin was prepared (MAGL23AF). In a previous work, the formulated inhibitor showed potency in ovarian and colon cancer cell lines in terms of IC50, and was tested on mice in order to assess its biocompatibility, organs biodistribution and toxicity. In the present work, we expanded the investigation to assess the potential in vivo application of MAGL23AF. Stability assays in serum and in human derived microsomes showed a good structural stability in physiological conditions of MAGL23AF. The antitumor efficacy tested on mice bearing ovarian cancer tumor xenografts demonstrated that MAGL23AF is more potent than the non-formulated drug, leading to necrosis-driven cancer cell death. In vivo studies revealed that albumin-complexed nanocrystals improved the therapeutic window of MAGL23, exhibiting a favorable biodistribution with slightly increased accumulation in the tumor. In conclusion, the MAGL23AF showed increased in vitro stability in conditions mirroring the bloodstream environment and hepatic metabolism coupled with an optimal antitumor efficacy in vivo. These results not only validates the efficacy of our formulation but also positions it as a promising strategy for addressing challenges related to the solubility of drugs in body fluids.

In Vitro Evaluation of Drug-Drug Interaction Potential of Epetraborole, a Novel Bacterial Leucyl-tRNA Synthetase Inhibitor.

Epetraborole (EBO) is a boron-containing inhibitor of bacterial leucyl-tRNA synthetase, with potent activity against nontuberculous mycobacteria (NTM) and Gram-negative bacteria, including Burkholderia pseudomallei. EBO is being developed for the treatment of NTM lung disease and melioidosis, administered in combination with other therapeutic agents in both diseases. Therefore, EBO and its major circulating metabolite M3 were evaluated in comprehensive drug-drug interaction (DDI) in vitro studies. The CYP inhibitory and substrate potential of EBO and M3 were assessed using hepatic microsomes. Stably transfected cells that expressed individual efflux or uptake transporters were used to determine whether EBO or M3 were substrates or inhibitors for these receptors. Stability studies indicated that EBO is a poor substrate for major CYP enzymes. Neither EBO nor M3 was a potent reversible or time-dependent inhibitor of major CYP enzymes. EBO was not an inducer of CYP1A2 mRNA, while it was a weak inducer of CYP2B6 and CYP3A4. EBO was a substrate only for OCT2. At clinically relevant concentrations, neither EBO nor M3 inhibited major human efflux or uptake transporters. Based on these data, at clinically relevant concentrations of EBO and M3, there is a low risk of victim or perpetrator DDI.

Halogenated class of oximes as a new class of monoamine oxidase-B inhibitors for the treatment of Parkinson’s disease: Synthesis, biochemistry, and molecular dynamics study

Oximes are the promising structural scaffold for inhibiting monoamine oxidase (MAO)-B. Eight chalcone-based oxime derivatives were synthesized by microwave-assisted technique, and their ability to inhibit human MAO (hMAO) enzymes were tested. All compounds showed higher inhibitory activity of hMAO-B than hMAO-A. In the CHBO subseries, CHBO4 most potently inhibited hMAO-B with an IC50 value of 0.031 μM, followed by CHBO3 (IC50 = 0.075 μM). In the CHFO subseries, CHFO4 showed the highest inhibition of hMAO-B with an IC50 value of 0.147 μM. Compound CHBO4 had the highest selectivity index (SI) value of 1290.3. However, CHBO3 and CHFO4 showed relatively low SI values of 27.7 and 19.2, respectively. The -Br substituent in the CHBO subseries at the para-position in the B-ring showed higher hMAO-B inhibition than the -F substituent in the CHFO subseries. In both series, hMAO-B inhibition increased with the substituents at para-position in A-ring (-F > -Br > -Cl > -H in order). Compound CHBO4 (-F in A-ring and -Br in B-ring) was 12.6-times potent than the substituents-reversed compound CHFO3 (-Br in A-ring and -F in B-ring; IC50 = 0.391 μM). In the kinetic study, Ki values of CHBO4 and CHFO4 for hMAO-B were 0.010 ± 0.005 and 0.040 ± 0.007 μM, respectively, with competitive inhibitions. Reversibility experiments showed that CHBO4 and CHFO4 were reversible hMAO-B inhibitors. In the cytotoxicity test using the Vero cells by the MTT technique, CHBO4 had low toxicity with an IC50 value of 128.8 µg/mL. In H2O2-induced cells, CHBO4 significantly reduced cell damage by scavenging reactive oxygen species (ROS). Molecular docking and dynamics showed the stable binding mode of the lead molecule CHBO4 on the active site of hMAO-B. These results suggest that CHBO4 is a potent reversible, competitive, and selective hMAO-B inhibitor and can be used as a treatment agent for neurological disorders.

Abstract 3099: Hnd-01: a potent inhibitor of wild type mutant BTK

Abstract Dasatinib is an oral dual BCR/ABL and Src family tyrosine kinase inhibitor approved for use in patients with chronic myelogenous leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. Based on the in vitro and in vivo characterization studies of dasatanib, several metabolites were identified. Dasatinib and its metabolite 20 were the major circulating species identified which represented 25.5% and 12.5% of total radioactivity in human plasma respectively. Here, we report the identification of HND-01, a small molecule inhibitor of Bruton’s tyrosine kinase (BTK) which was achieved by modifying metabolite 20 of dasatinib. Bruton’s tyrosine kinase (BTK) is a non-receptor kinase and a key regulator of the B-cell receptor (BCR) signaling pathway. BCR is critical for proliferation and survival of leukemic cells in many B cell malignancies, including chronic lymphocytic leukemia (CLL). BTK is a key target for the development of small molecule inhibitors in B cell malignancies. There are several covalent BTK inhibitors including ibrutinib that have been approved. These covalent inhibitors bind with high affinity to Cys-481 in the active site of BTK. However, some patients develop acquired resistance to ibrutinib due to Cys-481 mutation in the BTK binding site. The acquired resistance to covalent inhibitors can be overcome with the design of new reversible BTK inhibitors. The reversible BTK inhibitors will bind to different sites other than the cysteine residue of BTK and inactivate BTK. These drugs would potentially be active in the presence or absence of the cysteine-to-serine mutation. HND-01, a novel and potent reversible BTK inhibitor inhibits wild type & C481S mutant BTK with IC50 values of 0.157 nM for WTBTK and 0.032 nM for C481SBTK. HND-01 inhibits K562 cell proliferation (IC50 0.183 nM) and it is more stable than dasatinib in human liver microsomes (in vitro clearance; 142 mL/min/kg for HND-01 vs 211 mL/min/kg for dasatinib). In an established human lymphoma efficacy model (TMD-8 model), HND-01 showed stronger tumor inhibition (80.6%) than Ibrutinib (58%). These data demonstrates that HND-01 is a BTK inhibitor that is more potent with potential desirable ADME properties than ibrutinib. HND-01 was filled for international patents, China patent application # 202080030953.6, US patent application #17/636,476, EU application # EP 20853834.8, and Canada application # CA 3148436. Citation Format: Jing Zhang, Ahmed A. Samatar, Yue Tan, Shiqing Pi, Zhigang Zhou, Yan Xu, Daihong Yang. Hnd-01: a potent inhibitor of wild type mutant BTK [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3099.

Abstract OT3-26-02: A Phase 3 study of gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor plus a non-steroidal aromatase inhibitor (VIKTORIA-1)

Abstract Background: Gedatolisib is a potent reversible dual inhibitor that selectively targets all Class I isoforms of phosphoinositide 3-kinase (PI3K) and mechanistic target of rapamycin (mTOR). Two separate pivotal clinical trials demonstrated that PI3K and mTOR inhibitors are active in combination with endocrine therapy and prolong progression-free survival (PFS) among patients with hormone receptor positive (HR+)/HER2-negative (HER2-) advanced breast cancer (ABC) who had previously received endocrine therapy (SOLAR-1, BOLERO-2). CDK4/6 inhibitor (CDK4/6i) therapy has been approved in the front-line setting. However, patients eventually experience disease progression on CDK4/6i based therapy. Available data indicates that resistance to CDK4/6i is a transient adaptive mechanism that may be reversed by adding inhibitors of the PI3K/mTOR pathway (PI3K/mTORi). Thus, combination of PI3K/mTORi and CDK4/6i in patients whose disease progressed on prior CDK4/6i could potentially both restore sensitivity to CDK4/6i and prevent adaptive activation of the PI3K/mTOR pathway. This hypothesis was evaluated in a Phase 1b study (Layman SABCS 2021). Subjects with HR+/HER2- ABC who were CDK4/6i pretreated received gedatolisib (180 mg IV weekly for 3 weeks, then one week off) in combination with standard doses of palbociclib and fulvestrant. Median PFS was 12.9 months, and overall response rate was 63%. Grade 3-4 adverse events (AE) were observed at a low rate, and toxicity was overall easily managed with available standards of care, and few patients discontinued treatment due to treatment-related adverse events (4%). The most common AE was stomatitis; hyperglycemia of any grade occurred in 26% of patients. This preliminary data, dosing schedule, and study population characteristics form the basis for the Phase 3 trial, VIKTORIA-1. Trial design: This Phase 3, open-label, randomized, multinational two-part clinical trial will evaluate the efficacy and safety of gedatolisib and fulvestrant with or without palbociclib in patients with HR+/HER2- ABC previously treated with any CDK4/6i in combination with non-steroidal aromatase inhibitor therapy. Those without tumor PIK3CA mutations will be assigned to Study 1 and those with PIK3CA mutations will be assigned to Study 2. Study 1 will include up to 351 subjects randomized in a 1:1:1 ratio to Arm A (gedatolisib, palbociclib, and fulvestrant), Arm B (gedatolisib plus fulvestrant), or Arm C (fulvestrant). For subjects in Arm C whose disease progresses, crossover to Arm A or B is allowed. Study 2 will include up to 350 subjects randomized in a 3:3:1 ratio to Arm D (gedatolisib, palbociclib, and fulvestrant), Arm E (alpelisib plus fulvestrant), or Arm F (gedatolisib plus fulvestrant). Key eligibility criteria include adults with confirmed metastatic or locally advanced breast cancer, any menopausal status for females, radiologically evaluable disease, and prior CDK4/6i treatment with non-steroidal AI. Prior therapy with SERD, including fulvestrant is allowed. Key exclusion criteria include prior treatment with a PI3K, protein kinase B (Akt), or mTOR inhibitor, prior treatment with chemotherapy for advanced disease, more than two lines of prior endocrine therapy, bone only disease with no soft tissue components, active CNS metastases, and type 1 diabetes or uncontrolled type 2 diabetes. The primary endpoint is PFS assessed by blinded independent central review (BICR) per RECIST v1.1. Secondary endpoints included overall survival (OS), safety and tolerability, ORR, duration of response, time to response, CBR, quality of life, and pharmacokinetics. This trial is open for enrollment. Citation Format: Sara Hurvitz, Fabrice Andre, Massimo Cristofanilli, Giuseppe Curigliano, Antonio Giordano, Hyo S. Han, Miguel Martín, Barbara Pistilli, Hope Rugo, Robert Wesolowski, Samuel Suzuki, Sarah C. Mutka, Igor Gorbatchevsky, Sibylle Loibl. A Phase 3 study of gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor plus a non-steroidal aromatase inhibitor (VIKTORIA-1) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-26-02.

Development of Isopropyl-Tailed Chalcones as a New Class of Selective MAO-B Inhibitors for the Treatment of Parkinson's Disorder.

Thirteen isopropyl chalcones (CA1-CA13) were synthesized and evaluated for their inhibitory activity against monoamine oxidase (MAO). All compounds inhibited MAO-B more effectively than MAO-A. Compound CA4 most potently inhibited MAO-B with an IC50 value of 0.032 μM, similar to that of CA3 (IC50 = 0.035 μM) and with high selectivity index (SI) values for MAO-B over MAO-A (SI = 49.75 and 353.23, respectively). The -OH (CA4) or -F (CA3) group at the para position on the A ring provided higher MAO-B inhibition than that of the other substituents (-OH ≥ -F > -Cl > -Br > -OCH2CH3 > -CF3). On the other hand, compound CA10 most potently inhibited MAO-A with an IC50 value of 0.310 μM and effectively MAO-B (IC50 = 0.074 μM). The Br-containing thiophene substituent (CA10) instead of the A ring showed the highest MAO-A inhibition. In a kinetic study, K i values of compounds CA3 and CA4 for MAO-B were 0.076 ± 0.001 and 0.027 ± 0.002 μM, respectively, and that of CA10 for MAO-A was 0.016 ± 0.005 μM. A reversibility study showed that CA3 and CA4 were reversible inhibitors of MAO-B and CA10 was a reversible inhibitor of MAO-A. In docking and molecular dynamics, the hydroxyl group of CA4 and two hydrogen bonds contributed to the stability of the protein-ligand complex. These results suggest that CA3 and CA4 are potent reversible selective MAO-B inhibitors and can be used for the treatment of Parkinson's disease.

Medicarpin and Homopterocarpin Isolated from Canavalia lineata as Potent and Competitive Reversible Inhibitors of Human Monoamine Oxidase-B

Thirteen compounds were isolated from the Canavalia lineata pods and their inhibitory activities against human monoamine oxidase-A (hMAO-A) and -B (hMAO-B) were evaluated. Among them, compounds 8 (medicarpin) and 13 (homopterocarpin) showed potent inhibitory activity against hMAO-B (IC50 = 0.45 and 0.72 µM, respectively) with selectivity index (SI) values of 44.2 and 2.07, respectively. Most of the compounds weakly inhibited MAO-A, except 9 (prunetin) and 13. Compounds 8 and 13 were reversible competitive inhibitors against hMAO-B (Ki = 0.27 and 0.21 µM, respectively). Structurally, the 3-OH group at A-ring of 8 showed higher hMAO-B inhibitory activity than 3-OCH3 group at the A-ring of 13. However, the 9-OCH3 group at B-ring of 13 showed higher hMAO-B inhibitory activity than 8,9-methylenedioxygroup at the B-ring of 12 (pterocarpin). In cytotoxicity study, 8 and 13 showed non-toxicity to the normal (MDCK) and cancer (HL-60) cells and moderate toxicity to neuroblastoma (SH-SY5Y) cell. Molecular docking simulation revealed that the binding affinities of 8 and 13 for hMAO-B (-8.7 and -7.7 kcal/mol, respectively) were higher than those for hMAO-A (-3.4 and -7.1 kcal/mol, respectively). These findings suggest that compounds 8 and 13 be considered potent reversible hMAO-B inhibitors to be used for the treatment of neurological disorders.

1716. In Vitro Drug-Drug Interaction Evaluation of Epetraborole, a Novel Bacterial Leucyl-tRNA Synthetase Inhibitor

Abstract Background Epetraborole (EBO) is a boron-containing oral inhibitor of bacterial leucyl-tRNA synthetase, an essential enzyme in protein synthesis; EBO demonstrates potent activity against nontuberculous mycobacteria. EBO is being developed for the treatment of Mycobacterium avium complex lung disease patients and will be used in combination with other drugs. Therefore, EBO and its major circulating metabolite M3 were evaluated in a comprehensive drug-drug interactions (DDI) risk assessment. Methods Stability of EBO was evaluated in human liver microsomes, hepatocytes and recombinant CYP enzymes. The inhibitory potential of EBO (0.03-100 μM) and M3 (1-1000 μM) on cytochrome P450 (CYP) activities was assessed using human hepatic microsomes. The CYP induction potential of EBO (25-200 μM), M3 was evaluated and compared to prototypical inducers in human hepatocytes (three donors) and mRNA. Fold increase in mRNA expression was utilized to investigate the CYP induction potential of EBO (0.3-100 µM) and M3 (1-250 µM). Stably transfected cell lines that expressed individual transporters were used to determine whether EBO or M3 were substrates or inhibitors for these proteins. Results In vitro studies with microsomes, hepatocytes and recombinant cytochrome P450 (CYP) enzymes indicated that EBO was a poor substrate for major CYP enzymes; drug interactions with epetraborole as victim are considered unlikely. Neither EBO nor its major metabolite M3 was a potent reversible or time-dependent inhibitor of major CYP enzymes. Half maximal inhibitory concentration (IC50) values for CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1 and 3A4 were >100 µM. EBO was not an inducer of CYP1A2 mRNA in human hepatocytes from three donors, while it was a weak inducer of CYP2B6 and CYP3A4. No induction of mRNA was observed in human hepatocytes at concentrations relevant to planned clinical doses. EBO is unlikely to be a substrate for P-gp, BCRP, OATP1B1, OATP1B3, OAT1, OAT3, MATE1 and MATE2K. EBO was an in vitro substrate for OCT2, a transporter involved in active renal secretion. At clinically relevant concentrations, neither EBO nor M3 inhibited major human efflux or uptake transporters. Conclusion At clinically relevant concentrations of EBO and its major circulating metabolite M3, there is a low risk of victim or perpetrator DDI. Disclosures Afshin Shafiee, PhD, AN2 Therapeutics: Stocks/Bonds Bradley K. Wong, PhD, AN2 Therapeutics: Advisor/Consultant Sanjay Chanda, PhD, AN2 Therapeutics: Stocks/Bonds.

Discovery of 2-Amino-7-sulfonyl-7H-pyrrolo[2,3-d]pyrimidine Derivatives as Potent Reversible FGFR Inhibitors with Gatekeeper Mutation Tolerance: Design, Synthesis, and Biological Evaluation.

Fibroblast growth factor receptors (FGFRs) play key roles in promoting cancer cell proliferation, differentiation, and migration. However, acquired resistance to FGFR inhibitors has become an emerging challenge in long-term cancer therapies, especially for hepatocellular carcinoma (HCC). Gatekeeper (GK) mutations are the main mechanism of resistance. Herein, we describe the discovery of a series of reversible FGFR inhibitors, particularly for GK mutations with the 2-amino-7-sulfonyl-7H-pyrrolo[2,3-d]pyrimidine scaffold. Rational design, optimization, and pharmacokinetic screening provided representative compound 19 with potent FGFR inhibition in vitro, high bioavailability, and an acceptable half-life. GK mutation tolerance was supported by assays against FGFR4V550L and Ba/F3-TEL-FGFR4V550L cells. Moreover, compound 19 exhibited potent antitumor potency in HUH7 xenograft mouse models with no obvious toxicity observed. Compound 19 was identified as a potential candidate for overcoming GK mutations for HCC treatment.

The Discovery of the Mode of Action of Nitisinone.

This review briefly discusses the discovery of the mode of action of the triketone herbicide, 2-(2-nitro-4-trifluormethylbenzoyl)-1,3-cyclohexanedione and its use as a drug Nitisinone for the treatment of inborn errors of tyrosine metabolism. Nitisinone is a potent reversible tight-binding inhibitor of the enzyme 4-hydroxyphenylpyruvate dioxygenase, involved in the catabolism of the amino acid tyrosine. Nitisinone is used to treat the rare disease hereditary tyrosinaemia type 1 where the last enzyme in the breakdown of tyrosine, fumarylacetoacetase is deficient. Nitisinone is also used to treat patients with alkaptonuria where the enzyme homogentisic acid oxidase is deficient. Articles in this issue discuss metabolites of tyrosine catabolism in healthy patients and those with alkaptonuria.

Construction of Covalent Bisubstrate Inhibitor of Protein Kinase Reacting with Cysteine Residue at Substrate-Binding Site.

Recent clinical success with targeted covalent inhibitors points to new possibilities for development of protein kinase (PK)-targeted drugs by exploiting reactive cysteine residues in and around the ATP-binding site. However, more than 300 human PKs lack cysteine residues in the ATP-binding site. Here, we report the first covalent bisubstrate PK inhibitor whose electrophilic warhead reaches outside the ATP-binding site and reacts with a distant cysteine residue. A series of covalent inhibitors and their reversible counterparts were synthesized and characterized. The most potent reversible inhibitor possessed picomolar affinity and its cysteine-reactive counterpart revealed high value of kinact/KI ratio (6.2 × 107 M-1 s-1) for the reaction with the catalytic subunit of cAMP-dependent PK (PKAc). Under optimized conditions, fluorescent dye-labeled covalent inhibitors demonstrated PKA-selectivity in the cell lysate and reacted with several proteins inside live cells, including PKAc. The disclosed compounds serve as leads for targeting PKs possessing an analogously positioned cysteine residue.

Assessing the Role of a Malonamide Linker in the Design of Potent Dual Inhibitors of Factor Xa and Cholinesterases.

The rational discovery of new peptidomimetic inhibitors of the coagulation factor Xa (fXa) could help set more effective therapeutic options (to prevent atrial fibrillation). In this respect, we explored the conformational impact on the enzyme inhibition potency of the malonamide bridge, compared to the glycinamide one, as a linker connecting the P1 benzamidine anchoring moiety to the P4 aryl group of novel selective fXa inhibitors. We carried out structure–activity relationship (SAR) studies aimed at investigating para- or meta-benzamidine as the P1 basic group as well as diversely decorated aryl moieties as P4 fragments. To this end, twenty-three malonamide derivatives were synthesized and tested as inhibitors of fXa and thrombin (thr); the molecular determinants behind potency and selectivity were also studied by employing molecular docking. The malonamide linker, compared to the glycinamide one, does significantly increase anti-fXa potency and selectivity. The meta-benzamidine (P1) derivatives bearing 2′,4′-difluoro-biphenyl as the P4 moiety proved to be highly potent reversible fXa-selective inhibitors, achieving inhibition constants (Ki) in the low nanomolar range. The most active compounds were also tested against cholinesterase (ChE) isoforms (acetyl- or butyrylcholinesterase, AChE, and BChE), and some of them returned single-digit micromolar inhibition potency against AChE and/or BChE, both being drug targets for symptomatic treatment of mild-to-moderate Alzheimer’s disease. Compounds 19h and 22b were selected as selective fXa inhibitors with potential as multimodal neuroprotective agents.

Abstract 1048: Synergistic drug combination of LSD1 and ABL2 inhibitors for Ewing's sarcoma identified in an arrayed CRISPR screen approach

Abstract Background: Ewing's Sarcoma (ES) is a rare and aggressive pediatric bone tumor that is driven by a chromosomal translocation and fusion between EWS and FLI1 genes resulting in a chimeric protein. Nearly 85% of ES cases express the EWS/FLI protein which functions as a transcription factor and drives oncogenesis. EWS/FLI interacts with lysine-specific demethylase 1 (LSD1) that is highly expressed in pediatric sarcomas, to repress critical tumor suppressors. We have developed a potent reversible LSD1 inhibitor, SP-2577 (Seclidemstat), that shows the ability to impair tissue culture cell viability in multiple ES cell lines and is currently in clinical trials. A more favorable therapeutic response to SP-2577 may be obtained by combining drugs that target multiple pathways and/or inhibit resistance mechanisms. Experimental Design: In this study, we applied an arrayed CRISPR screening (Synthego) to identify survival genes that can be candidates for molecularly targeted drugs. Gene candidates were validated using western blot, qPCR, soft agar assay. Ewing’s Sarcoma A673 ABL2i knockdown and scramble cell lines were generated, implanted into nude mice, and treated with SP-2577. Lastly, combinational drug treatments using FDA-approved inhibitors with SP-2577 were tested in 2D and 3D cultures. Results: CRISPR druggable library screen identified that downregulation of several genes resulted in increased SP-2577 cytotoxicity in multiple ES cell lines. Importantly, ABL2 knockdown was found to have a significant synergy in combination with SP-2577 treatment, both in vitro and in vivo. siRNA knockdown of ABL2 in combination with SP-2577 treatment revealed an increase in JNK signaling and Cleaved Caspases-3 activation with decreased Src phosphorylation. This data suggests that downregulation of ABL2 in combination with SP-2577 treatment promotes activation of apoptosis pathways in ES. In addition, combination treatment of SP-2577 with drugs targeting ABL2 pathway showed high synergy in vitro. Conclusion: This study highlights the potential for a combination treatment of SP-2577 with ABL2 inhibitors in ES patients. Further, our observations support the capability of arrayed CRISPR screening to identify new therapeutic strategies in ES. Citation Format: Samuel Sampson, Trason Thode, Kevin Drenner, Ryan Rodriguez Del Villar, Annika Ozols, Mohan Kaadige, Alexis Weston, Serina Ng, Tithi Ghosh Halder, Shelby Rheinschmidt, David Anderson, Kevin Holden, Raffaella Soldi, Sunil Sharma. Synergistic drug combination of LSD1 and ABL2 inhibitors for Ewing's sarcoma identified in an arrayed CRISPR screen approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1048.

Abstract 167: Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations

Abstract The fibroblast growth factor receptor (FGFR) family of protein tyrosine kinases plays a role in many physiological processes including angiogenesis and wound healing. FGFR mutations, fusions, rearrangements, and amplifications have been linked to the pathogenesis of multiple tumor types. For example, approximately 10-15% of patients with intrahepatic cholangiocarcinoma have FGFR2 fusions, and amplification of FGFR2 is prevalent in gastric cancer and implicated in tumor growth. Approved FGFR inhibitors produce responses in patients that harbor FGFR genetic alterations but show reduced activity against key mutations (e.g., V565, N550, etc.). These pan-FGFR inhibitors also frequently show dose-limiting toxicities including hyperphosphatemia which can be linked to the inhibition of FGFR1. To address these issues, a novel series of FGFR inhibitors that are potent and selective reversible inhibitors of FGFR2 with selectivity over FGFR1 have been identified. This series also maintains activity against clinically relevant mutations in the FGFR2 protein. Inhibition of cellular FGFR phosphorylation was measured using engineered cell lines to demonstrate that the inhibitors target both wild-type FGFR2 and activating FGFR2 mutations while sparing FGFR1. In addition, CDX tumor models showed in vivo target engagement and FGFR isoform selectivity. Herein, the in vitro and in vivo characterization of a representative selective reversible FGFR2 inhibitor is described. Citation Format: John Fischer, Karyn Bouhana, Mark J. Chicarelli, Josh Dahlke, Brad Fell, Jennifer Fulton, Anna Guarnieri, Ravi Jalluri, Amber Johnson, Brent Mclean, Max Mejia, Rob Rieger, John Robinson, Mareli Rodriguez, Francis Sullivan, Yang Wang, Shannon Winski, Yeyun Zhou. Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 167.

Identification of Infigratinib as a Potent Reversible Inhibitor and Mechanism-Based Inactivator of CYP2J2: Nascent Evidence for a Potential In Vivo Metabolic Drug-Drug Interaction with Rivaroxaban.

Infigratinib (INF) is a fibroblast growth factor receptor inhibitor that was recently United States Food and Drug Administration-approved for the treatment of advanced or metastatic cholangiocarcinoma. We previously established that INF inhibited and inactivated cytochrome P450 3A4 (CYP3A4). Here, in a follow up to our previous study, we identified for the first time that INF also elicited potent competitive inhibition and mechanism-based inactivation of CYP2J2 with kinetic parameters K i, K I, k inact, and a partition ratio of 1.94 µM, 0.10 µM, 0.026 minute-1, and ∼3, respectively, when rivaroxaban was harnessed as the probe substrate. Inactivation was revealed to exhibit cofactor-dependency and was attenuated by an alternative substrate (astemizole) and direct inhibitor (nilotinib) of CYP2J2. Additionally, the nature of inactivation was unlikely to be pseudo-irreversible and instead arose from covalent modification due to the lack of substantial enzyme activity recovery after dialysis and chemical oxidation, as well as the lack of a resolvable Soret band in spectral scans. Glutathione trapping confirmed that the identity of the putative reactive intermediate implicated in the covalent inactivation of both CYP2J2 and CYP3A4 was identical and likely attributable to an electrophilic p-benzoquinonediimine intermediate of INF. Finally, mechanistic static modeling revealed that by integrating the previously arcane inhibition and inactivation kinetic parameters of CYP2J2-mediated rivaroxaban hydroxylation by INF illuminated in this work, together with those previously documented for CYP3A4, a 49% increase in the systemic exposure of rivaroxaban was projected. Our modeling results predicted a potential risk of metabolic drug-drug interactions between the clinically relevant combination of rivaroxaban and INF in the setting of cancer. SIGNIFICANCE STATEMENT: This study reported that INF elicits potent reversible inhibition and mechanism-based inactivation of CYP2J2. Furthermore, static modelling predicted that its coadministration with the direct oral anticoagulant rivaroxaban may potentially culminate in a metabolic drug-drug interaction (DDI) leading to an increased risk of major bleeding. As rivaroxaban is steadily gaining prominence as the anticoagulant of choice in the treatment of cancer-associated venous thromboembolism, the DDI projections reported here are clinically relevant and warrant further investigation via physiologically based pharmacokinetic modelling and simulation.

Pharmacological Inhibition of FAK-Pyk2 Pathway Protects Against Organ Damage and Prolongs the Survival of Septic Mice.

Sepsis and septic shock are associated with high mortality and are considered one of the major public health concerns. The onset of sepsis is known as a hyper-inflammatory state that contributes to organ failure and mortality. Recent findings suggest a potential role of two non-receptor protein tyrosine kinases, namely Focal adhesion kinase (FAK) and Proline-rich tyrosine kinase 2 (Pyk2), in the inflammation associated with endometriosis, cancer, atherosclerosis and asthma. Here we investigate the role of FAK-Pyk2 in the pathogenesis of sepsis and the potential beneficial effects of the pharmacological modulation of this pathway by administering the potent reversible dual inhibitor of FAK and Pyk2, PF562271 (PF271) in a murine model of cecal ligation and puncture (CLP)-induced sepsis. Five-month-old male C57BL/6 mice underwent CLP or Sham surgery and one hour after the surgical procedure, mice were randomly assigned to receive PF271 (25 mg/kg, s.c.) or vehicle. Twenty-four hours after surgery, organs and plasma were collected for analyses. In another group of mice, survival rate was assessed every 12 h over the subsequent 5 days. Experimental sepsis led to a systemic cytokine storm resulting in the formation of excessive amounts of both pro-inflammatory cytokines (TNF-α, IL-1β, IL-17 and IL-6) and the anti-inflammatory cytokine IL-10. The systemic inflammatory response was accompanied by high plasma levels of ALT, AST (liver injury), creatinine, (renal dysfunction) and lactate, as well as a high, clinical severity score. All parameters were attenuated following PF271 administration. Experimental sepsis induced an overactivation of FAK and Pyk2 in liver and kidney, which was associated to p38 MAPK activation, leading to increased expression/activation of several pro-inflammatory markers, including the NLRP3 inflammasome complex, the adhesion molecules ICAM-1, VCAM-1 and E-selectin and the enzyme NOS-2 and myeloperoxidase. Treatment with PF271 inhibited FAK-Pyk2 activation, thus blunting the inflammatory abnormalities orchestrated by sepsis. Finally, PF271 significantly prolonged the survival of mice subjected to CLP-sepsis. Taken together, our data show for the first time that the FAK-Pyk2 pathway contributes to sepsis-induced inflammation and organ injury/dysfunction and that the pharmacological modulation of this pathway may represents a new strategy for the treatment of sepsis.

The Roles of Aromatase Inhibitors in Treating Hypogonadism and Male Infertility

Testis is an organ with both endocrine and exocrine functions. The former stands for testosterone release, and the latter represents sperm production. Spermatogenesis is a process highly depending on adequate supply of testosterone by the Leydig cells of the testis. In men at the reproductive age, more than 90% of testosterone produced is used for spermatogenesis. In men with diminished testosterone secretion in testis, or hypogonadism, the spermatogenesis process is impaired. Testosterone can be converted into estradiol through the catalyzation of aromatase, a cytochrome P450 enzyme presented in the peripheral tissue. Blocking the activity of aromatase causes an elevation of serum testosterone and a decrease of serum estradiol levels. These effects result in an increase of testosterone-to-estradiol ratio. Infertile males with dysfunction of spermatogenesis may demonstrate a low testosterone-to-estradiol ratio. Studies have shown that aromatase inhibitors (AIs) are beneficial to treat patients with impaired spermatogenesis, by demonstrating improvement of the semen parameters in men with oligoasthenoteratozoospermia. Besides, AIs can also be applied in other health issues, such as hypogonadism-related erectile dysfunction, short statue, depression, or male breast cancer. There are two different types of AIs: steroidal and nonsteroidal. Steroidal AI (e.g., testolactone) is an irreversible, but weaker inhibitors, while nonsteroidal AIs (e.g., letrozole and anastozole) are potent reversible inhibitors. Both types of AIs demonstrate plausible effects to improve semen parameters. In this review, the physiological action of aromatase and the indications of AIs treatment are discussed in detail, especially focusing on the function of spermatogenesis in infertile men.

A carrier free delivery system of a monoacylglycerol lipase hydrophobic inhibitor

Monoacylglycerol lipase (MAGL) is an emerging therapeutic target for cancer. It is involved in lipid metabolism and its inhibition impairs many hallmarks of cancer including cell proliferation, migration/invasion and tumor growth. For these reasons, our group has recently developed a potent reversible MAGL inhibitor (MAGL23), which showed promising anticancer activities. Here in, to improve its pharmacological properties, a nanoformulation based on nanocrystals coated with albumin was prepared for therapeutic applications. MAGL23 was solubilized by a nanocrystallization method with Pluronic F-127 as surfactant into an organic solvent and was recovered as nanocrystals in water after solvent evaporation. Finally, the solubilized nanocrystals were stabilized by human serum albumin to create a smart delivery carrier. An in-silico prediction (lipophilicity, structure at different pH and solubility in water), as well as experimental studies (solubility), have been performed to check the chemical properties of the inhibitor and nanocrystals. The solubility in water increases from less than 0.01 mg/mL (0.0008 mg/mL, predicted) up to 0.82 mg/mL in water. The formulated inhibitor maintained its potency in ovarian and colon cancer cell lines as the free drug. Furthermore, the system was thoroughly observed at each step of the solubilization process till the final formulation stage by different spectroscopic techniques and a comparative study was performed to check the effects of Pluronic F-127 and CTAB as surfactants. The formulated system is favorable to release the drug at physiological pH conditions (at pH 7.4, after 24 h, less than 20% of compound is released). In vivo studies have shown that albumin-complexed nanocrystals increase the therapeutic window of MAGL23 along with a favorable biodistribution. As per our knowledge, we are reporting the first ever nanoformulation of a MAGL inhibitor, which is promising as a therapeutic system where the MAGL enzyme is involved, especially for cancer therapeutic applications.

Abstract 1175: Identification of novel combination therapies with the LSD1 inhibitor SP-2577 (Seclidemstat) in Ewing's Sarcoma using a complete druggable CRISPR library approach

Abstract Introduction: Ewing's Sarcoma (ES) is a rare and aggressive pediatric bone tumor that is driven by a chromosomal translocation and fusion between EWS and FLI1 genes resulting in a chimeric protein. Nearly 85% of ES cases express the EWS/FLI protein which functions as a transcription factor and drives oncogenesis. It has been previously observed in ES patient samples have high levels of the histone lysine specific demethylase 1 (LSD1). LSD1 is recruited by EWS/FLI as a member of the nucleosome remodeling and histone deacetylase (NuRD) complex to repress the critical EWS/FLI targets LOX and TGFBR2. Treatment with the potent LSD1 reversible inhibitor, SP-2577 (Seclidemstat), causes de-repression of these genes and impaired tissue culture cell viability in multiple ES cell lines. In this study we investigated new targeted therapies to use in combination with SP-2577 to help increase the cytotoxicity of the drug within ES cell types. Methods: Synthego® arrayed CRISPR screening platform was used to knock down genes associated with known druggable interactions in the ES cell line SK-N-MC. Genes were knocked down singularly either in the presence/absence of SP-2577. Viability screening was used to determine genes that increased the cytotoxicity of SP-2577. Statistical analysis, z-score, and IPA analysis was performed to investigate correlations between loss of gene effect and LSD1 pathway. Hit-gene validation was performed using siRNA and/or sgRNA knockdown/knockout, and other methods such as qPCR, and western blot assay for protein expression. Results: Arrayed CRISPR screening identified 103 gene deletions that resulted in increased SP-2577 cytotoxicity in SK-N-MC cell line. Among those, the top 19 hits were selected by identifying a FDA approved drug-gene interaction. Two high- interest hits were seen to have significant interaction with the LSD1 pathway: ABL2 and SH2B3. Drug combination treatment of SP-2577 with either Ruxolitinib or Dasatinib in ES cell lines showed high synergy at low dose ratio. Downstream pathways analysis confirmed the efficacy of the drugs combination. Detailed data will be presented. Conclusion: Our data support the validity of the arrayed CRISPR screening to identify new therapeutic strategies in ES, and highlights the potential for Ruxolitinib or Dasatinib treatment in combination with SP-2577 in ES patients. Citation Format: Samuel Sampson, Trason Thode, Mohan Kaadige, Alexis Weston, Serina Ng, Kevin Drenner, Raffaella Soldi, Sunil Sharma. Identification of novel combination therapies with the LSD1 inhibitor SP-2577 (Seclidemstat) in Ewing's Sarcoma using a complete druggable CRISPR library approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1175.

Discovery of HBW-3-20, the first potent reversible inhibitor of Bruton’s tyrosine kinase (BTK) with high brain exposure.

e15068 Background: It has been an on-demand task to develop a BTK inhibitor of significant brain exposure, a critical property for extending its usages to treat Primary Central Nervous System Lymphoma (PCNSL) and autoimmune disorders. PCNSL is an aggressive extra nodal non-Hodgkin lymphoma that exclusively invades the central nervous system (CNS). Tirabrutinib, an irreversible BTK inhibitor with limited brain exposure, is the first BTK inhibitor approved for the treatment of recurrent or refractory primary central nervous system lymphoma recently. PRN2246 is another irreversible BTK inhibitor claimed to be of brain exposure, and is currently in clinical trials for the treatment of multiple sclerosis. Methods: New reversible BTK inhibitors were designed, synthesized and tested for enzymatic activities against wild-type and C481S-mutated BTK. Highly active compounds were confirmed for growth effects in diffuse large B-cell lymphoma derived TMD8 cells. Their microsomal stability and ADME properties were also assessed. Potent and bioavailable compounds were further measured for brain exposures in rats. Results: HBW-3-20 has excellent potency against both wild-type and C481S-mutated BTK, with IC50 of 2.5 and 3.8 nM, respectively. Its TMD8 cellular potency is 72 nM. In a head-to-head direct comparison of brain exposure experiment, HBW-3-20, tirabrutinib and PRN2246 were all dosed at 10mg/kg orally. The brain and plasma concentration were measured after 1 hour and the data are shown in the table below. The brain to plasma ratio for HBW-3-20, tirabrutinib and PRN2246 are 58%, 11.8% and 4.2% respectively. Our results show that HBW-3-20 has much greater brain permeability than tirabrutinib or PRN2246 in rats. Conclusions: HBW-3-20 is the first potent reversible BTK inhibitor that shows promisingly high brain permeability. HBW-3-20 provides a very valuable clinical candidate for treating B-cell malignancies in brain and autoimmune disorders![Table: see text]