A phase II study of relapsed/refractory AML patients with activating FLT3 mutations revealed that crenolanib (dosage of 200 mg, three times/day continuously in 28-day cycles) induced a CR with an incomplete count recovery (CRi) in 23% of FLT3/tyrosine kinase inhibitor (TKI) naïve patients, and in 5% of patients previously treated with TKI against FLT3 [68]. Here, FLT3 is linked to acute myeloid leukemia.