2-Aminopyridine-Based Mitogen-Activated Protein Kinase Kinase Kinase Kinase 4 (MAP4K4) Inhibitors: Assessment of Mechanism-Based Safety.

Studies have linked the serine-threonine kinase MAP4K4 to the regulation of a number of biological processes and/or diseases, including diabetes, cancer, inflammation, and angiogenesis. With a majority of the members of our lead series (e.g., 1) suffering from time-dependent inhibition (TDI) of CYP3A4, we sought design avenues that would eliminate this risk. One such approach arose from the observation that carboxylic acid-based intermediates employed in our discovery efforts retained high MAP4K4 inhibitory potency and were devoid of the TDI risk. The medicinal chemistry effort that led to the discovery of this central nervous system-impaired inhibitor together with its preclinical safety profile is described.

39-week toxicity and toxicokinetic study of ponezumab (PF-04360365) in cynomolgus monkeys with 12-week recovery period.

Ponezumab (PF-04360365) is a novel humanized IgG2Δa monoclonal antibody that binds to amyloid-ß (Aß). It is designed to have reduced immune effector function compared to other passive immunotherapies for Alzheimer's disease (AD). Toxicity was evaluated in cynomolgus monkeys treated intravenously with vehicle or 10, 30, or 100 mg/kg of ponezumab every 10th day for up to 39 weeks, and after a 12-week recovery phase. The Aß peptide sequence of monkeys is identical to that of humans. No substantial difference in test article exposure between sexes was observed, and mean plasma Cmax and AUC0-n were approximately dose-proportional. Ponezumab was detectable approximately 9 weeks after cessation of dosing. All animals, except two males given 10 mg/kg, maintained exposure to test article. One of these males tested positive for anti-ponezumab antibodies. Ponezumab was detected in the cerebrospinal fluid (CSF) of animals given active treatment. The estimated CSF/plasma ponezumab concentration ratio was <0.008 after multiple doses. At the end of the dosing and recovery phases, plasma Aß1-40 and Aß1-x were increased in treated animals versus controls. No test article-related effects were seen after ophthalmogical, cardiovascular, physical examinations, and clinical and anatomic pathology evaluations. Plasma concentrations of ponezumab on day 261 at the no observed adverse effect level of 100 mg/kg were 22.4 and 5.3 times greater on a Cmax and AUC basis, respectively, than human exposures at the highest dose (10 mg/kg) in a single-dose Phase I trial. These data suggest an acceptable safety profile for ponezumab as an immunotherapy for AD.

Chronic administration of an aglycosylated murine antibody of ponezumab does not worsen microhemorrhages in aged Tg2576 mice.

Cerebral vasogenic edema and microhemorrhages are potential safety concerns for compounds intended to treat subjects with Alzheimer's disease (AD) by targeting amyloid ß (Aß). Ponezumab (PF-04360365) is an investigational anti-Aß monoclonal antibody. Two hundred female mice (APP(K670N;M671L); Tg2576) 16-19 months old received an aglycosylated CHO-derived murine surrogate of ponezumab by intraperitoneal administration once weekly for up to 26 weeks at doses of 0, 10, 30, or 100 mg/kg. Drug exposure and plasma Aß levels increased with increasing dose. After 26 weeks, the 100 mg/kg group had significantly greater plasma levels of Aß(1-x) and Aß(x-40) than the vehicle group (p < 0.001). Brain microhemorrhages were identified histologically using hematoxylin and eosin and/or Perls' Prussian blue iron staining. The incidence in the vehicle group was equal to or higher than those of the treated groups. There was no evidence of vasogenic edema. In summary, intraperitoneal administration of a murine surrogate of ponezumab to aged Tg2576 mice for up to 6 months did not produce any compound-related brain microhemorrhage or other pathologies.

Toxicity and carcinogenicity studies of chlorpromazine hydrochloride and p-cresidine in the p53 heterozygous mouse model.

The carcinogenic potential of chlorpromazine hydrochloride, a psychotropic agent, was assessed in the p53 heterozygous mouse assay. In a 4-week dose range finding study in p53 wild-type mice, doses of 20,40, 60, and 80 mg/kg were poorly tolerated because of mortality secondary to the severe sedative and hypotensive effects of chlorpromazine. Based on 40% mortality at a dose of 20 mg/kg in the dose-range finding study, a high dose of 10 mg/kg was chosen for the 26-week carcinogenicity study in p53 heterozygous mice. Doses of 2.5, 5, and 10 mg/kg chlorpromazine hydrochloride were well tolerated in the 26-week study. The administration of chlorpromazine hydrochloride at dose levels up to and including 10 mg/kg to p53 heterozygous and wild-type mice did not result in a dose-related increase in tumor incidence or in the type of tumors seen in comparison to controls. Findings related to the administration of chlorpromazine in the 26-week study were limited to minimal uterine and ovarian atrophy in p53 wild-type mice dosed with 10 mg/kg chlorpromazine hydrochloride. However, p53 heterozygous mice administered 400 mg/kg p-cresidine, a genotoxic carcinogen commonly used as a positive control for this model, developed urinary bladder tumors. Administration of p-cresidine also resulted in a regenerative anemia, splenic and hepatic hemosiderosis, renal findings, and ovarian and uterine atrophy. This study demonstrated that chlorpromazine hydrochloride, at the doses tolerated, was not carcinogenic in the p53 heterozygous mouse assay.