Induction of remission in patients with acute myeloid leukemia without prolonged myelosuppression using diphtheria toxin-interleukin 3 fusion protein

7068 The recombinant diphtheria toxin fusion protein, DT388IL3, composed of the catalytic and translocation domains of diphtheria toxin (DT388) fused to human interleukin-3 (IL3) showed selective cytotoxicity to acute myeloid leukemia (AML) stem cells both in vitro and in vivo and was prepared for a phase I clinical study (Urieto, Protein Exp Purif 33, 123, 2004). FDA approval (BB IND#11314) and IRB approvals were obtained. Seventy-five AML patients were screened and thirty-one patients treated. The median age of treated patients was 62 years (range, 25- 81 years). There were sixteen males and fifteen females. Disease was de novo in three, first relapse in ten, second relapse in eight, and refractory in ten patients. Four patients had a history of MDS, and one had a history of secondary AML. One patient each had previously received an autologous or allogeneic stem cell transplant. Cytogenetics were unfavorable in ten, intermediate in nineteen, and not done in two. Seven patients were treated with 4 μg/kg,...