An orally bioavailable, mono-anilino-pyrimidine, mutant-selective epidermal growth factor receptor (EGFR) inhibitor, with potential antineoplastic activity. Upon oral administration, EGFR mutant-selective inhibitor PLB1004 targets, binds to and irreversibly inhibits the activity of various EGFR mutations, including exon 20 insertion (Ex20ins) activating mutations, the gatekeeper mutation T790M, ExDel19, and L858R. This prevents EGFR-mediated signaling, induces cell death and inhibits tumor growth in tumor cells expressing these EGFR mutations. EGFR, a receptor tyrosine kinase mutated in many tumor cell types, plays a key role in tumor cell proliferation and tumor vascularization.