A series of quinazolin-4-one based hydroxamic acids was rationally designed and synthesized as novel dual PI3K/HDAC inhibitors by incorporating an HDAC pharmacophore into a PI3K inhibitor (Idelalisib) via an optimized linker. Several of these dual inhibitors were highly potent (IC50 < 10 nM) and selective against PI3Kγ, δ and HDAC6 enzymes and exhibited good antiproliferative activity against multiple cancer cell lines. The lead compound 48c, induced necrosis in several mutant and FLT3-resistant AML cell lines and primary blasts from AML patients, while showing no cytotoxicity against normal PBMCs, NIH3T3, and HEK293 cells. Target engagement of PI3Kδ and HDAC6 by 48c was demonstrated in MV411 cells using the cellular thermal shift assay (CETSA). Compound 48c showed good pharmacokinetics properties in mice via intraperitoneal (ip) administration and provides a means to examine the biological effects of inhibiting these two important enzymes with a single molecule, either in vitro or in vivo.

PURPOSE: Metarrestin is a first-in-class pyrrolo-pyrimidine-derived small molecule targeting a marker of genome organization associated with metastasis and is currently in preclinical development as an anti-cancer agent. Here, we report the in vitro ADME characteristics and in vivo pharmacokinetic behavior of metarrestin. METHODS: Solubility, permeability, and efflux ratio as well as in vitro metabolism of metarrestin in hepatocytes, liver microsomes and S9 fractions, recombinant cytochrome P450 (CYP) enzymes, and potential for CYP inhibition were evaluated. Single dose pharmacokinetic profiles after intravenous and oral administration in mice, rat, dog, monkey, and mini-pig were obtained. Simple allometric scaling was applied to predict human pharmacokinetics. RESULTS: Metarrestin had an aqueous solubility of 150 µM at pH 7.4, high permeability in PAMPA and moderate efflux ratio in Caco-2 assays. The compound was metabolically stable in liver microsomes, S9 fractions, and hepatocytes from six species, including human. Metarrestin is a CYP3A4 substrate and, in mini-pigs, is also directly glucuronidated. Metarrestin did not show cytochrome P450 inhibitory activity. Plasma concentration-time profiles showed low to moderate clearance, ranging from 0.6 mL/min/kg in monkeys to 48 mL/min/kg in mice and moderate to high volume of distribution, ranging from 1.5 L/kg in monkeys to 17 L/kg in mice. Metarrestin has greater than 80% oral bioavailability in all species tested. The excretion of unchanged parent drug in urine was < 5% in dogs and < 1% in monkeys over collection periods of ≥ 144 h; in bile-duct cannulated rats, the excretion of unchanged drug was < 1% in urine and < 2% in bile over a collection period of 48 h. CONCLUSIONS: Metarrestin is a low clearance compound which has good bioavailability and large biodistribution after oral administration. Biotransformation appears to be the major elimination process for the parent drug. In vitro data suggest a low drug-drug interaction potential on CYP-mediated metabolism. Overall favorable ADME and PK properties support metarrestin's progression to clinical investigation.

Tyrosine kinase domain (TKD) mutations contribute to acquired resistance to FMS-like tyrosine kinase 3 (FLT3) inhibitors used to treat FLT3-mutant acute myeloid leukemia (AML). We report a cocrystal structure of FLT3 with a type I inhibitor, NCGC1481, that retained potent binding and activity against FLT3 TKD and gatekeeper mutations. Relative to the current generation of advanced FLT3 inhibitors, NCGC1481 exhibited superior antileukemic activity against the common, clinically relevant FLT3-mutant AML cells in vitro and in vivo.

Th17 cells are critical drivers of autoimmune diseases and immunopathology. There is an unmet need to develop therapies targeting pathogenic Th17 cells for the treatment of autoimmune disorders. Here, we report that anxiolytic FGIN-1-27 inhibits differentiation and pathogenicity of Th17 cells in vitro and in vivo using the experimental autoimmune encephalomyelitis (EAE) model of Th17 cell-driven pathology. Remarkably, we found that the effects of FGIN-1-27 were independent of translocator protein (TSPO), the reported target for this small molecule, and instead were driven by a metabolic switch in Th17 cells that led to the induction of the amino acid starvation response and altered cellular fatty acid composition. Our findings suggest that the small molecule FGIN-1-27 can be re-purposed to relieve autoimmunity by metabolic reprogramming of pathogenic Th17 cells.

Creatine transporter deficiency (CTD) is a metabolic disorder resulting in cognitive, motor, and behavioral deficits. Cyclocreatine (cCr), a creatine analog, has been explored as a therapeutic strategy for the treatment of CTD. We developed a rapid, selective, and accurate HILIC ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to simultaneously quantify the intracellular concentrations of cCr, creatine (Cr), creatine-d3 (Cr-d3), phosphocyclocreatine (pcCr), and phosphocreatine (pCr). Using HILIC-UPLC-MS/MS, we measured cCr and Cr-d3 uptake and their conversion to the phosphorylated forms in primary human control and CTD fibroblasts. Altogether, the data demonstrate that cCr enters cells and its dominant intracellular form is pcCr in both control and CTD patient cells. Therefore, cCr may replace creatine as a therapeutic strategy for the treatment of CTD.

The biosynthesis of sialic acid (Neu5Ac) leads to the intracellular production of cytidine-5'-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac), the active sialic acid donor to nascent glycans (glycoproteins and glycolipids) in the Golgi. UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase myopathy is a rare autosomal recessive muscular disease characterized by progressive muscle weakness and atrophy. To quantify the intracellular levels of CMP-Neu5Ac as well as N-acetylmannosamine (ManNAc) and Neu5Ac in human leukocytes, we developed and validated robust liquid chromatography-tandem mass spectrometry methods. A fit-for-purpose approach was implemented for method validation. Hydrophilic interaction chromatography was used to retain three hydrophilic analytes. The human leukocyte pellets were lysed and extracted in a methanol-water mixture and the leukocyte extract was used for LC-MS/MS analysis. The lower limits of quantitation for ManNAc, Neu5Ac and CMP-Neu5Ac were 25.0, 25.0 and 10.0 ng/ml, respectively. These validated methods were applied to a clinical study.

Fumarate hydratase (FH) is a metabolic enzyme that is part of the Krebs cycle and reversibly catalyzes the hydration of fumarate to malate. Mutations of the FH gene have been associated with fumarate hydratase deficiency (FHD), hereditary leiomyomatosis and renal cell cancer (HLRCC), and other diseases. Currently, there are no high-quality small-molecule probes for studying human FH. To address this, we developed a quantitative high-throughput screening (qHTS) FH assay and screened a total of 57,037 compounds from in-house libraries in dose-response. While no inhibitors of FH were confirmed, a series of phenyl-pyrrolo-pyrimidine-diones were identified as activators of human FH. These compounds were not substrates of FH, were inactive in a malate dehydrogenase counterscreen, and showed no detectable reduction-oxidation activity. The binding of two compounds from the series to human FH was confirmed by microscale thermophoresis. The low hit rate in this screening campaign confirmed that FH is a "tough target" to modulate, and the small-molecule activators of human FH reported here may serve as a starting point for further optimization and development into cellular probes of human FH and potential drug candidates.

Targeted inhibitors to oncogenic kinases demonstrate encouraging clinical responses early in the treatment course; however, most patients will relapse because of target-dependent mechanisms that mitigate enzyme-inhibitor binding or through target-independent mechanisms, such as alternate activation of survival and proliferation pathways, known as adaptive resistance. Here, we describe mechanisms of adaptive resistance in FMS-like receptor tyrosine kinase (FLT3)-mutant acute myeloid leukemia (AML) by examining integrative in-cell kinase and gene regulatory network responses after oncogenic signaling blockade by FLT3 inhibitors (FLT3i). We identified activation of innate immune stress response pathways after treatment of FLT3-mutant AML cells with FLT3i and showed that innate immune pathway activation via the interleukin-1 receptor-associated kinase 1 and 4 (IRAK1/4) complex contributes to adaptive resistance in FLT3-mutant AML cells. To overcome this adaptive resistance mechanism, we developed a small molecule that simultaneously inhibits FLT3 and IRAK1/4 kinases. The multikinase FLT3-IRAK1/4 inhibitor eliminated adaptively resistant FLT3-mutant AML cells in vitro and in vivo and displayed superior efficacy as compared to current targeted FLT3 therapies. These findings uncover a polypharmacologic strategy for overcoming adaptive resistance to therapy in AML by targeting immune stress response pathways.

Aqueous solubility is one of the most important properties in drug discovery, as it has profound impact on various drug properties, including biological activity, pharmacokinetics (PK), toxicity, and in vivo efficacy. Both kinetic and thermodynamic solubilities are determined during different stages of drug discovery and development. Since kinetic solubility is more relevant in preclinical drug discovery research, especially during the structure optimization process, we have developed predictive models for kinetic solubility with in-house data generated from 11,780 compounds collected from over 200 NCATS intramural research projects. This represents one of the largest kinetic solubility datasets of high quality and integrity. Based on the customized atom type descriptors, the support vector classification (SVC) models were trained on 80% of the whole dataset, and exhibited high predictive performance for estimating the solubility of the remaining 20% compounds within the test set. The values of the area under the receiver operating characteristic curve (AUC-ROC) for the compounds in the test sets reached 0.93 and 0.91, when the threshold for insoluble compounds was set to 10 and 50 μg/mL respectively. The predictive models of aqueous solubility can be used to identify insoluble compounds in drug discovery pipeline, provide design ideas for improving solubility by analyzing the atom types associated with poor solubility and prioritize compound libraries to be purchased or synthesized.

Niemann-Pick type C1 (NPC1) disease is a fatal neurovisceral disease for which there are no FDA approved treatments, though cyclodextrin (HPβCD) slows disease progression in preclinical models and in an early phase clinical trial. Our goal was to evaluate the mechanism of action of a previously described combination-therapy, Triple Combination Formulation (TCF) - comprised of the histone deacetylase inhibitor (HDACi) vorinostat/HPβCD/PEG - shown to prolong survival in Npc1 mice. In these studies, TCF's benefit was attributed to enhanced vorinostat pharmacokinetics (PK). Here, we show that TCF reduced lipid storage, extended lifespan, and preserved neurological function in Npc1 mice. Unexpectedly, substitution of an inactive analog for vorinostat in TCF revealed similar efficacy. We demonstrate that the efficacy of TCF was attributable to enhanced HPβCD PK and independent of NPC1 protein expression. We conclude that although HDACi effectively reduce cholesterol storage in NPC1-deficient cells, HDACi are ineffective in vivo in Npc1 mice.