Nonclinical safety of the sodium-glucose cotransporter 2 inhibitor empagliflozin.

Empagliflozin, a selective inhibitor of the renal tubular sodium-glucose cotransporter 2, was developed for treatment of type 2 diabetes mellitus. Nonclinical safety of empagliflozin was studied in a battery of tests to support global market authorization. Safety pharmacology studies indicated no effect of empagliflozin on measures of respiratory or central nervous system function in rats or cardiovascular safety in telemeterized dogs. In CD-1 mouse, Wistar Han rat, or beagle dogs up to 13, 26, or 52 weeks of treatment, respectively, empagliflozin exhibited a toxicity profile consistent with secondary supratherapeutic pharmacology related to glucose loss and included decreased body weight and body fat, increased food consumption, diarrhea, dehydration, decreased serum glucose and increases in other serum parameters reflective of increased protein catabolism, gluconeogenesis, and electrolyte imbalances, and urinary changes such as polyuria and glucosuria. Microscopic changes were consistently observed in kidney and included tubular nephropathy and interstitial nephritis (dog), renal mineralization (rat) and tubular epithelial cell karyomegaly, single cell necrosis, cystic hyperplasia, and hypertrophy (mouse). Empagliflozin was not genotoxic. Empagliflozin was not carcinogenic in female mice or female rats. Renal adenoma and carcinoma were induced in male mice only at exposures 45 times the maximum clinical dose. These tumors were associated with a spectrum of nonneoplastic changes suggestive of a nongenotoxic, cytotoxic, and cellular proliferation-driven mechanism. In male rats, testicular interstitial cell tumors and hemangiomas of the mesenteric lymph node were observed; both tumors are common in rats and are unlikely to be relevant to humans. These studies demonstrate the nonclinical safety of empagliflozin.

Discovery of A-770041, a src-family selective orally active lck inhibitor that prevents organ allograft rejection.

We describe the identification, SAR, and pharmacology of the src-family selective lck inhibitor A-770041 that prolongs the survival of major histocompatibility mismatched allografts in models of solid organ transplant rejection for greater than 65 days.

Modest inflammation enhances diclofenac hepatotoxicity in rats: role of neutrophils and bacterial translocation.

Idiosyncratic adverse drug reactions (IADRs) represent an important human health problem, yet animal models for preclinical prediction of these reactions are lacking. Recent evidence in animals suggests that some IADRs arise from drug interaction with an inflammatory episode that renders the liver sensitive to injury. Diclofenac (DCLF) is one of those drugs for which the clinical use is limited by idiosyncratic liver injury. We tested the hypothesis that modest inflammation triggered in rats by a small dose of lipopolysaccharide (LPS) renders a nonhepatotoxic dose of DCLF injurious to liver. Cotreatment of rats with nonhepatotoxic doses of LPS and DCLF resulted in elevated serum alanine aminotransferase activity and liver histopathologic changes 6 h after DCLF administration. Neither LPS nor DCLF alone had such an effect. Gene array analysis of livers revealed a unique gene expression pattern in the LPS/DCLF-cotreated group compared with groups given either agent alone. Antiserum-induced neutrophil (PMN) depletion in LPS/DCLF-cotreated rats protected against liver injury, demonstrating a role for PMNs in the pathogenesis of this LPS/DCLF interaction. Gut sterilization of LPS/DCLF-treated rats did not protect against liver injury. In contrast, gut sterilization did attenuate liver injury caused by a large, hepatotoxic dose of DCLF, suggesting that hepatotoxicity induced by large doses of DCLF is caused in part by its ability to increase intestinal permeability to endotoxin or other bacterial products. These results demonstrate that inflammation-DCLF interaction precipitates hepatotoxicity in rats and raise the possibility of creating animal models that predict human IADRs.

Microarray analysis of lipopolysaccharide potentiation of trovafloxacin-induced liver injury in rats suggests a role for proinflammatory chemokines and neutrophils.

Idiosyncratic drug toxicity refers to toxic reactions occurring in a small subset of patients and usually cannot be predicted during preclinical or early phases of clinical trials. One hypothesis for the pathogenesis of hepatic idiosyncratic drug reactions is that, in certain individuals, underlying inflammation results in sensitization of the liver, such that injury occurs from an agent that typically would not cause hepatotoxicity at a therapeutic dose. We explored this possibility by cotreating rats with nonhepatotoxic doses of bacterial lipopolysaccharide (LPS) and trovafloxacin (TVX), a drug that caused idiosyncratic hepatotoxicity in humans. The combination of LPS and TVX resulted in hepatotoxicity in rats, as determined by increases in serum alanine aminotransferase activity and hepatocellular necrosis, which were not observed with either agent alone. In contrast, treatment with LPS and levofloxacin, a fluoroquinolone without human idiosyncratic liability, did not result in these changes. Liver gene expression analysis identified unique changes induced by the combination of TVX and LPS, including enhanced expression of chemokines, suggestive of liver neutrophil (PMN) accumulation and activation. Consistent with a role for PMN in the hepatotoxicity induced by LPS/TVX, prior depletion of PMN attenuated the liver injury. The results suggest that gene expression profiles predictive of idiosyncratic liability can be generated in rats cotreated with LPS and drug. Furthermore, they identify gene expression changes that could be explored as biomarkers for idiosyncratic toxicity and lead to enhanced understanding of the mechanism(s) underlying hepatotoxicity induced by TVX.

A-770041, a novel and selective small-molecule inhibitor of Lck, prevents heart allograft rejection.

Lck, one of eight members of the Src family of tyrosine kinases, is activated after T cell stimulation and is required for T-cell proliferation and interleukin (IL)-2 production. Inhibition of Lck has been a target to prevent lymphocyte activation and acute rejection. Here, we report the pharmacologic characterization of 1-methyl-1H-indole-2-carboxylic acid (4-{1-[4-(4-acetyl-piperazin-l-yl)-cyclohexyl]-4-amino-1H-pyrazolo[3,4-d]pyrimidin-3-yl}-2-methoxy-phenyl)-amide (A-770041), an orally bioavailable pyrazolo[3,4-d]pyrimidine with increased selectivity for Lck compared with previously reported compounds. A-770041 is a 147 nM inhibitor of Lck (1 mM ATP) and is 300-fold selective against Fyn, the other Src family kinase involved in T-cell signaling. Concanavalin A-stimulated IL-2 production in whole blood is inhibited by A-770041 with an EC50 of approximately 80 nM. A-770041 is orally bioavailable (F = 34.1 +/- 7.2% at 10 mg/kg) and has a t(1/2) of 4.1 +/- 0.1 h. Concanavalin A-induced IL-2 production in vivo is inhibited by oral administration of A-770041 (in vivo EC50 = 78 +/- 28 nM). Doses of A-770041 at or above 10 mg/kg/day prevent rejection of hearts transplanted heterotopically in rats from Brown Norway donors to Lewis recipients across a major histocompatibility barrier for least 65 days. Grafts from animals treated with 20 mg/kg/day A-770041 or 10 mg/day Cyclosporin A had minimal microvascular changes or multifocal mononuclear infiltrates. However, mineralization in myocytes from the grafts from A-770041-treated animals was less than animals treated with Cyclosporin A. Lck inhibition is an attractive target to prevent acute rejection.