Conversely, the first-generation multitargeted tyrosine kinase inhibitors (TKIs) that also inhibit FLT3 (e.g., midostaurin and sorafenib) initially demonstrated only modest single-agent activity in relapsed FLT3-ITD-mutated AML [31, 32], albeit with improved response rates and survival when combined with chemotherapy [33, 34]. Here, FLT3 is linked to acute myeloid leukemia.