Thomas R. Simpson

Assessment of Biomarkers of Drug-Induced Kidney Injury in Cynomolgus Monkeys Treated with a Triple Reuptake Inhibitor

Drug-induced kidney injury (DIKI) results in attrition during drug development; new DIKI urinary biomarkers offer potential to detect and monitor DIKI progression and regression, but frequently only in rats. The triple reuptake inhibitor (TRI) PRC200-SS represents a new class of antidepressants that elevate synaptic levels of serotonin, norepinephrine, and dopamine and is expected to produce more rapid onset and better antidepressant efficacy than single or dual inhibitors. Although preclinical studies and recent clinical trials lend support to this concept of superior efficacy for TRIs, there is little information on the safety profile of this class of compounds. Using histopathology and DIKI biomarkers, in single- and repeat dose toxicological studies in cynomolgus monkeys, PRC200-SS demonstrated dose-proportional kidney toxicity. Characterization of the histopathological lesions, using a combination of immunohistochemistry (IHC) and urinary biomarker analysis, indicated that the compound is a distal tubule and collecting duct toxicant. Segment specificity for the lesions was shown using a newly developed triple IHC combination method with antibodies against calbindin D28, aquaporin 2, and aquaporin 1. Urinary biomarker analyses, using multiplex immunoassays, confirmed a dose-proportional increase in the excretion of calbindin D28 and clusterin in compound-treated monkeys with levels returning to baseline during the drug-free recovery period. These results constitute the validation of distal nephron DIKI biomarkers in the cynomolgus monkey and demonstrate the utility of calbindin D28 and clusterin to monitor the progression of distal nephron DIKI, representing potential early biomarkers of DIKI for the clinic.

4-Aryl piperazine and piperidine amides as novel mGluR5 positive allosteric modulators

Positive allosteric modulation of metabotropic glutamate receptor 5 (mGluR5) is regarded as a potential novel treatment for schizophrenic patients. Herein we report the synthesis and SAR of 4-aryl piperazine and piperidine amides as potent mGluR5 positive allosteric modulators (PAMs). Several analogs have excellent activity and desired drug-like properties. Compound 2b was further characterized as a PAM using several in vitro experiments, and produced robust activity in several preclinical animal models.

In vitro assessment of metabolic drug–drug interaction potential of AZD2624, neurokinin-3 receptor antagonist, through cytochrome P450 enzyme identification, inhibition, and induction studies

AZD2624 was pharmacologically characterized as a NK3 receptor antagonist intended for treatment of schizophrenia. The metabolic drug–drug interaction potential of AZD2624 was evaluated in in vitro studies. CYP3A4 and CYP3A5 appeared to be the primary enzymes mediating the formation of pharmacologically active ketone metabolite (M1), whereas CYP3A4, CYP3A5, and CYP2C9 appeared to be the enzymes responsible for the formation of the hydroxylated metabolite (M2). The apparent Km values were 1.5 and 6.3 µM for the formation of M1 and M2 in human liver microsomes, respectively. AZD2624 exhibited an inhibitory effect on microsomal CYP3A4/5 activities with apparent IC50 values of 7.1 and 19.8 µM for midazolam and testosterone assays, respectively. No time-dependent inactivation of CYP3A4/5 activity (midazolam 1′-hydroxylation) by AZD2624 was observed. AZD2624 demonstrated weak to no inhibition of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP2D6. AZD2624 was not an inducer of CYP1A2 or CYP2B6. Although AZD2624-induced CYP3A4 activity in hepatocytes, the potential of AZD2624 to cause inductive drug interactions of this enzyme was low at relevant exposure concentration. Together with targeted low efficacious concentration, the results of this study demonstrated AZD2624 has a relatively low metabolic drug–drug interaction potential towards co-administered drugs. However, metabolism of AZD2624 might be inhibited when co-administrated with potent CYP3A4/5 inhibitors.

Synthesis and SAR of sulfoxide substituted carboxyquinolines as NK3 receptor antagonists

The neurokinin-3 (NK3) receptor is regarded as a potential novel target for treating patients with schizophrenia. Herein we report the synthesis and SAR of a series of C3-alkylsulfoxide substituted quinolines as potent NK3 receptor antagonists. These compounds have excellent NK3 functional activity, good selectivity and drug-like properties. Several key compounds have good in vitro/in vivo DMPK characteristics, and are active in a gerbil locomotor activity model.