Definition

An orally bioavailable, mutant-selective, small molecule inhibitor of human epidermal growth factor receptor (EGFR) and epidermal growth factor receptor 2 (HER2), with potential antineoplastic activity. Upon oral administration, EGFR/HER2 mutant-selective inhibitor STX-721 targets, binds to, and inhibits the activity of EGFR and HER2 with exon20 insertion mutations, thereby preventing EGFR- and HER2-mediated signaling. This may result in the inhibition of tumor growth and angiogenesis, and tumor regression in EGFR/HER2-expressing tumors. EGFR and HER2, receptor tyrosine kinases mutated or overexpressed in many tumor cell types, play major roles in tumor cell proliferation and tumor vascularization.