Novel thiazole amine class tyrosine kinase inhibitors induce apoptosis in human mast cells expressing D816V KIT mutation

Gain-of-function mutations of receptor tyrosine kinase KIT play a critical role in the pathogenesis of systemic mastocytosis (SM) and gastrointestinal stromal tumors. D816V KIT mutation, found in ∼80% of SM, is resistant to the currently available tyrosine kinase inhibitors (TKIs) (e.g. imatinib mesylate). Therefore, development of promising TKIs for the treatment of D816V KIT mutation is still urgently needed. We synthesized thiazole amine compounds and chose one representative designated 126332 to investigate its effect on human mast cells expressing KIT mutations. We found 126332 inhibited the phosphorylation of KIT and its downstream signaling molecules Stat3 and Stat5. 126332 inhibited the proliferation of D816V KIT expressing cells. 126332 induced apoptosis and downregulated levels of Mcl-1 and survivin. Furthermore, 126332 inhibited the tyrosine phosphorylation of β-catenin, inhibited β-catenin-mediated transcription and DNA binding of TCF. Moreover, 126332 also exhibited in vivo antineoplastic activity against cells harboring D816V mutation. Our findings suggest thiazole amine compounds may be promising agents for the treatment of diseases caused by KIT mutation.