An orally available inhibitor of epidermal growth factor receptor (EGFR), including activating mutations, with potential antineoplastic activity. Upon administration, the EGFR inhibitor TY-9591 binds to and inhibits EGFR activating mutations, including the resistance mutation T790M, which prevents EGFR mutant-mediated signaling and leads to cell death in EGFR mutant-expressing tumor cells. EGFR, a receptor tyrosine kinase mutated in many tumor cell types, plays a key role in tumor cell proliferation and tumor vascularization.