Discovery and Optimization of 2H-1λ2-Pyridin-2-one Inhibitors of Mutant Isocitrate Dehydrogenase 1 for the Treatment of Cancer.

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are oncogenic for a number of malignancies, primarily low-grade gliomas and acute myeloid leukemia. We report a medicinal chemistry campaign around a 7,7-dimethyl-7,8-dihydro-2H-1λ2-quinoline-2,5(6H)-dione screening hit against the R132H and R132C mutant forms of isocitrate dehydrogenase (IDH1). Systematic SAR efforts produced a series of potent pyrid-2-one mIDH1 inhibitors, including the atropisomer (+)-119 (NCATS-SM5637, NSC 791985). In an engineered mIDH1-U87-xenograft mouse model, after a single oral dose of 30 mg/kg, 16 h post dose, between 16 and 48 h, (+)-119 showed higher tumoral concentrations that corresponded to lower 2-HG concentrations, when compared with the approved drug AG-120 (ivosidenib).

Safety assessment of metarrestin in dogs: A clinical candidate targeting a subnuclear structure unique to metastatic cancer cells.

Pancreatic cancer is a leading cause of cancer-related deaths in the U.S. Ninety percent of patients with stage IV pancreatic cancer die within one year of diagnosis due to complications of metastasis. A metastatic potential of cancer cells has been shown to be closely associated with formation of perinucleolar compartment (PNC). Metarrestin, a first-in-class PNC inhibitor, was evaluated for its toxicity, toxicokinetics, and safety pharmacology in beagle dogs following every other day oral (capsule) administration for 28 days to support its introduction into clinical trials. The study consisted of four dose groups: vehicle; 0.25, 0.75 and 1.50 mg/kg/dose. Metarrestin reached its maximum concentration in blood at 3 h (overall median Tmax) across all doses with a mean t1/2 over 168 h of 55.5 h. Dose dependent increase in systemic exposure (Cmax and AUClast) with no sex difference was observed on days 1 and 27. Metarrestin accumulated from Day 1 to Day 27 at all dose levels and in both sexes by an overall factor of about 2.34. No mortality occurred during the dosing period; however, treatment-related clinical signs of toxicity consisting of hypoactivity, shaking/shivering, thinness, irritability, salivation, abnormal gait, tremors, ataxia and intermittent seizure-like activity were seen in both sexes at mid and high dose groups. Treatment-related effects on body weight and food consumption were seen at the mid and high dose levels. Safety pharmacology study showed no treatment-related effects on blood pressure, heart rate, corrected QT, PR, RR, or QRS intervals, or respiratory function parameters (respiratory rate, tidal volume, minute volume). There were no histopathological changes observed, with the exception of transient thymic atrophy which was considered to be non-adverse. Based primarily on clinical signs of toxicity, the No Observed Adverse Effect Level (NOAEL) in dogs was considered to be 0.25 mg/kg metarrestin after every other day dosing for 28 days with a mean of male and female Cmax = 82.5 ng/mL and AUClast = 2521 h*ng/mL, on Day 27.

Metabolism and pharmacokinetics characterization of metarrestin in multiple species.

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.

Identification of 4-phenylquinolin-2(1H)-one as a specific allosteric inhibitor of Akt.

Akt plays a major role in tumorigenesis and the development of specific Akt inhibitors as effective cancer therapeutics has been challenging. Here, we report the identification of a highly specific allosteric inhibitor of Akt through a FRET-based high-throughput screening, and characterization of its inhibitory mechanism. Out of 373,868 compounds screened, 4-phenylquinolin-2(1H)-one specifically decreased Akt phosphorylation at both T308 and S473, and inhibited Akt kinase activity (IC50 = 6 µM) and downstream signaling. 4-Phenylquinolin-2(1H)-one did not alter the activity of upstream kinases including PI3K, PDK1, and mTORC2 as well as closely related kinases that affect cell proliferation and survival such as SGK1, PKA, PKC, or ERK1/2. This compound inhibited the proliferation of cancer cells but displayed less toxicity compared to inhibitors of PI3K or mTOR. Kinase profiling efforts revealed that 4-phenylquinolin-2(1H)-one does not bind to the kinase active site of over 380 human kinases including Akt. However, 4-phenylquinolin-2(1H)-one interacted with the PH domain of Akt, apparently inducing a conformation that hinders S473 and T308 phosphorylation by mTORC2 and PDK1. In conclusion, we demonstrate that 4-phenylquinolin-2(1H)-one is an exquisitely selective Akt inhibitor with a distinctive molecular mechanism, and a promising lead compound for further optimization toward the development of novel cancer therapeutics.