To study insulin-like growth factor 2 (IGF2) imprinting in BWS (Beckwith-Wiedemann syndrome, an overgrowth syndrome associated with Wilms and other embryonal tumours), we examined allele-specific expression using an Apal polymorphism in the 3' untranslated region of IGF2. Four of six BWS fibroblast strains demonstrated biallelic expression, as did the tongue tissue from one of these patients. Paternal heterodisomy was excluded for all BWS patients with biallelic expression, suggesting strongly that the BWS phenotype in some patients involves disruption of IGF2 imprinting. Constitutional loss of IGF2 imprinting in a subgroup of our BWS patients, and recent reports of loss of imprinting in sporadic Wilms tumour, further strengthens the view that IGF2 overexpression plays an important role in somatic overgrowth and the development of embryonal tumours.

2-aminothiazole (1) was discovered as a novel Src family kinase inhibitor template through screening of our internal compound collection. Optimization through successive structure-activity relationship iterations identified analogs 2 (Dasatinib, BMS-354825) and 12m as pan-Src inhibitors with nanomolar to subnanomolar potencies in biochemical and cellular assays. Molecular modeling was used to construct a putative binding model for Lck inhibition by this class of compounds. The framework of key hydrogen-bond interactions proposed by this model was in agreement with the subsequent, published crystal structure of 2 bound to structurally similar Abl kinase. The oral efficacy of this class of inhibitors was demonstrated with 12m in inhibiting the proinflammatory cytokine IL-2 ex vivo in mice (ED50 approximately 5 mg/kg) and in reducing TNF levels in an acute murine model of inflammation (90% inhibition in LPS-induced TNFalpha production when dosed orally at 60 mg/kg, 2 h prior to LPS administration). The oral efficacy of 12m was further demonstrated in a chronic model of adjuvant arthritis in rats with established disease when administered orally at 0.3 and 3 mg/kg twice daily. Dasatinib (2) is currently in clinical trials for the treatment of chronic myelogenous leukemia.

A novel structural class of p38 mitogen-activated protein (MAP) kinase inhibitors consisting of substituted 4-(phenylamino)-pyrrolo[2,1- f][1,2,4]triazines has been discovered. An initial subdeck screen revealed that the oxindole-pyrrolo[2,1- f][1,2,4]triazine lead 2a displayed potent enzyme inhibition (IC 50 60 nM) and was active in a cell-based TNFalpha biosynthesis inhibition assay (IC 50 210 nM). Replacement of the C4 oxindole with 2-methyl-5- N-methoxybenzamide aniline 9 gave a compound with superior p38 kinase inhibition (IC 50 10 nM) and moderately improved functional inhibition in THP-1 cells. Further replacement of the C6 ester of the pyrrolo[2,1- f][1,2,4]triazine with amides afforded compounds with increased potency, excellent oral bioavailability, and robust efficacy in a murine model of acute inflammation (murine LPS-TNFalpha). In rodent disease models of chronic inflammation, multiple compounds demonstrated significant inhibition of disease progression leading to the advancement of 2 compounds 11b and 11j into further preclinical and toxicological studies.

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