Acceleration of infectious disease drug discovery and development using a humanized model of drug metabolism

A key step in drug discovery, common to many disease areas, is preclinical demonstration of efficacy in a mouse model of disease. However, this demonstration and its translation to the clinic can be impeded by mouse-specific pathways of drug metabolism. Here we show that a mouse line extensively humanized for the cytochrome P450 gene superfamily (“8HUM”) can circumvent these problems. The pharmacokinetics, metabolite profiles and magnitude of drug-drug interactions of a test set of approved medicines were in much closer alignment with clinical observations than in wild-type mice. Infection with Mycobacterium tuberculosis, Leishmania donovani and Trypanosoma cruzi was well tolerated in 8HUM, permitting efficacy assessment. During such assessments, mouse-specific metabolic liabilities were bypassed while the impact of clinically relevant active metabolites and DDI on efficacy were well-captured. Removal of species differences in metabolism by replacement of wild-type mice with 8HUM therefore reduces compound attrition while improving clinical translation, accelerating drug discovery

Neurobehavioral consequences of chronic intrauterine opioid exposure in infants and preschool children: a systematic review and meta-analysis

<b>Background</b><p></p> It is assumed within the accumulated literature that children born of pregnant opioid dependent mothers have impaired neurobehavioral function as a consequence of chronic intrauterine opioid use.<p></p> <b>Methods</b><p></p> Quantitative and systematic review of the literature on the consequences of chronic maternal opioid use during pregnancy on neurobehavioral function of children was conducted using the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We searched Cinahl, EMBASE, PsychINFO and MEDLINE between the periods of January 1995 to January 2012.<p></p> <b>Results</b><p></p> There were only 5 studies out of the 200 identified that quantitatively reported on neurobehavioral function of children after maternal opioid use during pregnancy. All 5 were case control studies with the number of exposed subjects within the studies ranging from 33–143 and 45–85 for the controls. This meta-analysis showed no significant impairments, at a non-conservative significance level of p < 0.05, for cognitive, psychomotor or observed behavioural outcomes for chronic intra-uterine exposed infants and pre-school children compared to non-exposed infants and children. However, all domains suggested a trend to poor outcomes in infants/children of opioid using mothers. The magnitude of all possible effects was small according to Cohen’s benchmark criteria.<p></p> <b>Conclusions</b><p></p> Chronic intra-uterine opioid exposed infants and pre-school children experienced no significant impairment in neurobehavioral outcomes when compared to non-exposed peers, although in all domains there was a trend to poorer outcomes. The findings of this review are limited by the small number of studies analysed, the heterogenous populations and small numbers within the individual studies. Longitudinal studies are needed to determine if any neuropsychological impairments appear after the age of 5 years and to help investigate further the role of environmental risk factors on the effect of ‘core’ phenotypes

Development of a 2,4-diaminothiazole series for the treatment of human African trypanosomiasis highlights the importance of static-cidal screening of analogues

While treatment options for human African trypanosomiasis (HAT) have improved significantly, there is still a need for new drugs with eradication now a realistic possibility. Here, we report the development of 2,4-diaminothiazoles that demonstrate significant potency against Trypanosoma brucei, the causative agent of HAT. Using phenotypic screening to guide structure-activity relationships, potent drug-like inhibitors were developed. Proof of concept was established in an animal model of the hemolymphatic stage of HAT. To treat the meningoencephalitic stage of infection, compounds were optimized for pharmacokinetic properties, including blood-brain barrier penetration. However, in vivo efficacy was not achieved, in part due to compounds evolving from a cytocidal to a cytostatic mechanism of action. Subsequent studies identified a nonessential kinase involved in the inositol biosynthesis pathway as the molecular target of these cytostatic compounds. These studies highlight the need for cytocidal drugs for the treatment of HAT and the importance of static-cidal screening of analogues

Trisubstituted Pyrimidines as Efficacious and Fast-acting Antimalarials

In this paper we describe the optimization of a phenotypic hit against Plasmodium falciparum, based on a trisubstituted pyrimidine scaffold. This led to compounds with good pharmacokinetics and oral activity in a P. berghei mouse model of malaria. The most promising compound (13) showed a reduction in parasitemia of 96% when dosed at 30 mg/kg orally once a day for 4 days in the P. berghei mouse model of malaria. It also demonstrated a rapid rate of clearance of the erythrocytic stage of P. falciparum in the SCID mouse model with an ED90 of 11.7 mg/kg when dosed orally. Unfortunately, the compound is a potent inhibitor of cytochrome P450 enzymes, probably due to a 4-pyridyl substituent. Nevertheless, this is a lead molecule with a potentially useful antimalarial profile, which could either be further optimized or be used for target hunting

Discovery of a quinoline-4-carboxamide derivative with a novel mechanism of action, multistage antimalarial activity, and potent in vivo efficacy

The antiplasmodial activity, DMPK properties, and efficacy of a series of quinoline-4-carboxamides are described. This series was identified from a phenotypic screen against the blood stage of Plasmodium falciparum (3D7) and displayed moderate potency but with suboptimal physicochemical properties and poor microsomal stability. The screening hit (1, EC50 = 120 nM) was optimized to lead molecules with low nanomolar in vitro potency. Improvement of the pharmacokinetic profile led to several compounds showing excellent oral efficacy in the P. berghei malaria mouse model with ED90 values below 1 mg/kg when dosed orally for 4 days. The favorable potency, selectivity, DMPK properties, and efficacy coupled with a novel mechanism of action, inhibition of translation elongation factor 2 (PfEF2), led to progression of 2 (DDD107498) to preclinical development

Cyclin-dependent kinase 12 is a drug target for visceral leishmaniasis

Visceral leishmaniasis causes considerable mortality and morbidity in many parts of the world. There is an urgent need for the development of new, effective treatments for this disease. Here we describe the development of an anti-leishmanial drug-like chemical series based on a pyrazolopyrimidine scaffold. The leading compound from this series (7, DDD853651/GSK3186899) is efficacious in a mouse model of visceral leishmaniasis, has suitable physicochemical, pharmacokinetic and toxicological properties for further development, and has been declared a preclinical candidate. Detailed mode-of-action studies indicate that compounds from this series act principally by inhibiting the parasite cdc-2-related kinase 12 (CRK12), thus defining a druggable target for visceral leishmaniasis