Definition

An orally bioavailable inhibitor of specific mutated forms of platelet-derived growth factor receptor alpha (PDGFR alpha; PDGFRa) and mast/stem cell factor receptor c-Kit (SCFR; CD117), with potential antineoplastic activity. Upon oral administration, PDGFR alpha/KIT mutant-specific inhibitor NB003 specifically targets, binds to and inhibits specific mutant forms of PDGFRa and c-Kit. This results in the inhibition of PDGFRa- and c-Kit-mediated signal transduction pathways and the inhibition of proliferation in tumor cells that express these PDGFRa and c-Kit mutants. PDGFRa and c-Kit, protein tyrosine kinases, are upregulated or mutated in various tumor cell types; they play key roles in the regulation of cellular proliferation and resistance to chemotherapy.