Mutations at the gatekeeper residues of BCR-ABL1 (eg, the threonine-to-isoleucine mutation at codon 315) and other oncogenic kinases have proven highly resistant to currently available TKIs.     ///    The rise and fall of gatekeeper mutations? The BCR-ABL1 T315I paradigm..     ///    "Imatinib mesylate, a breakpoint cluster region-Abelson BCR-ABL1 inhibitor, was the first TKI approved in cancer medicine and has served as a model for the development of similar agents for other cancers. "