Discovery and Pharmacokinetic and Pharmacological Properties of the Potent and Selective MET Kinase Inhibitor 1-{6-[6-(4-Fluorophenyl)-[1,2,4]triazolo[4,3-b]pyridazin-3-ylsulfanyl]benzothiazol-2-yl}-3-(2-morpholin-4-ylethyl)urea (SAR125844).

The HGF/MET pathway is frequently activated in a variety of cancer types. Several selective small molecule inhibitors of the MET kinase are currently in clinical evaluation, in particular for NSCLC, liver, and gastric cancer patients. We report herein the discovery of a series of triazolopyridazines that are selective inhibitors of wild-type (WT) MET kinase and several clinically relevant mutants. We provide insight into their mode of binding and report unprecedented crystal structures of the Y1230H variant. A multiparametric chemical optimization approach allowed the identification of compound 12 (SAR125844) as a development candidate. In this chemical series, absence of CYP3A4 inhibition was obtained at the expense of satisfactory oral absorption. Compound 12, a promising parenteral agent for the treatment of MET-dependent cancers, promoted sustained target engagement at tolerated doses in a human xenograft tumor model. Preclinical pharmacokinetics conducted in several species were predictive for the observed pharmacokinetic behavior of 12 in cancer patients.

The selective intravenous inhibitor of the MET tyrosine kinase SAR125844 inhibits tumor growth in MET-amplified cancer.

Activation of the MET/HGF pathway is common in human cancer and is thought to promote tumor initiation, metastasis, angiogenesis, and resistance to diverse therapies. We report here the pharmacologic characterization of the triazolopyridazine derivative SAR125844, a potent and highly selective inhibitor of the MET receptor tyrosine kinase (RTK), for intravenous administration. SAR125844 displayed nanomolar activity against the wild-type kinase (IC50 value of 4.2 nmol/L) and the M1250T and Y1235D mutants. Broad biochemical profiling revealed that SAR125844 was highly selective for MET kinase. SAR125844 inhibits MET autophosphorylation in cell-based assays in the nanomolar range, and promotes low nanomolar proapoptotic and antiproliferative activities selectively in cell lines with MET gene amplification or pathway addiction. In two MET-amplified human gastric tumor xenograft models, SNU-5 and Hs 746T, intravenous treatment with SAR125844 leads to potent, dose- and time-dependent inhibition of the MET kinase and to significant impact on downstream PI3K/AKT and RAS/MAPK pathways. Long duration of MET kinase inhibition up to 7 days was achieved with a nanosuspension formulation of SAR125844. Daily or every-2-days intravenous treatment of SAR125844 promoted a dose-dependent tumor regression in MET-amplified human gastric cancer models at tolerated doses without treatment-related body weight loss. Our data demonstrated that SAR125844 is a potent and selective MET kinase inhibitor with a favorable preclinical toxicity profile, supporting its clinical development in patients with MET-amplified and MET pathway-addicted tumors.

Discovery of the first non-ATP competitive IGF-1R kinase inhibitors: advantages in comparison with competitive inhibitors.

A new series of IGF-1R inhibitors related to hydantoins were identified from a lead originating from HTS. Their noncompetitive property as well as their slow binding characteristics provided a series of compounds with unique selectivity and excellent cellular activities.

Design of potent IGF1-R inhibitors related to bis-azaindoles.

From an azaindole lead, identified in high throughput screen, a series of potent bis-azaindole inhibitors of IGF1-R have been synthesized using rational drug design and SAR based on a in silico binding mode hypothesis. Although the resulting compounds produced the expected improved potency, the model was not validated by the co-crystallization experiments with IGF1-R.

2-Chloro-3-pyridin-3-yl-5,6,7,8-tetrahydroindolizine-1-carboxamide (CMV423), a new lead compound for the treatment of human cytomegalovirus infections.

Human cytomegalovirus (HCMV) remains one of the major pathogens in immunocompromised patients (AIDS and transplants) and the main cause for congenital infections leading from slight cognitive defects up to severe mental retardation. The drugs that are currently available for the treatment of HCMV infections, i.e. ganciclovir, foscarnet and cidofovir, are all acting at the level of the viral DNA polymerase. Here we describe an entirely new molecule, the 2-chloro-3-pyridin-3-yl-5,6,7,8-tetrahydroindolizine-1-carboxamide (CMV423), that shows very potent in vitro activity against HCMV. CMV423 is highly active against HCMV reference strains and clinical isolates, but also against those strains, isolated from patients or emerging after in vitro selection, that are resistant to either ganciclovir, foscarnet or cidofovir. CMV423 also showed activity in two ex vivo models, that are both highly relevant for the pathophysiology of HCMV, the retinal pigment epithelial and the bone marrow stromal cell assays. Viral antigen expression analysis by flow cytometry, as well as time of addition experiments, confirmed that CMV423 acts on a step of the viral replicative cycle that precedes the DNA polymerase step and, most likely, coincides with the immediate early (IE) antigen synthesis. Finally, CMV423 combined with either ganciclovir, foscarnet or cidofovir in checkerboard experiments demonstrated a highly synergistic activity.