CD19/CD22 chimeric antigen receptor T-cell therapy for refractory acute B-cell lymphoblastic leukemia with FLT3-ITD mutations.

Treatment of acute lymphoblastic leukemia (ALL) is still a challenge despite years of researching, especially for those of poor prognosis. Zhang and his team recently proved that FLT3 gene mutation was identified in ~5% of ALL and the mutation spectrum is different from AML. Recently, chimeric antigen receptor T cells (CART) therapy presents great efficacy in treating refractory leukemia. We report a case of a refractory ALL patient with FLT3-ITD mutations and unfavorable karyotypes, who failed to respond to chemotherapy and small molecule tyrosine kinase inhibitors, successfully treated by CART therapy. FLT3-ITD mutations were downregulated dramatically into 14.1% positive 3 days after the infusion and remained negative until now. MRD has stayed to be negative from the 10th day. This case suggests that CART-cell therapy might be effective in treating FLT3-ITD positive refractory ALL, implying the possibility to overcome the traditional prognosis scoring system for leukemia and providing a new chance for other leukemia patients with inferior prognosis factors.