Ann Hematol (1993) 66:67-70 Annals of Hematology 9 Springer-Verlag 1993 Original article Chemotherapy for minimally differentiated acute myeloid leukemia (AML-MO) A report on five cases and. review of the literature N. Yokose 1, K. Ogata 1, T. Ito 1, K. Miyake 1, E. An 1, K. Inokuchi 1, To Yamada 1, S. Gomi 1, Y. TanabO, I. Ohki 1, T. Kuwabara ~, S. Hasegawa 1, T. Shinohara 2, K. Dan 1, and T. Nomura ~ 1 Third Department of Internal Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113, Japan 2 Department of Human Genetics, Japan Red Cross Medical Center, 4-1-22 Hiroo, Shibuya-ku, Tokyo 150, Japan Received May 25, 1992/Accepted October 29, 1992 Summary. With the objective of establishing the optimal therapy for minimally differentiated acute myeloid leuke- mia (AML-M0), we examined the therapeutic results of five AML-M0 cases and reviewed the literature. In a series of 63 patients with newly diagnosed acute leukemia who were admitted to the Main Hospital of Nippon Me- dical School, five patients fit the criteria for AML-M0: negative myeloperoxidase (MPO) and Sudan black B re- action by light microscopy, negative for B- and T-lineage markers, and positive for myeloid markers. They were treated by means of AdVP [adriamycin, vincristine, and prednisolone (PSL)] therapy and/or BHAC-DMP [behe- noylcytosine arabinoside (BHAC), daunorubicin (DNR), 6-mercaptopurine (6-MP), and PSL] therapy. The AdVP therapy was unsuccessful in the two patients who received it, while a complete remission (CR) was achieved with the BHAC-DMP therapy in three of four patients. Although one patient treated with BHAC-DMP did not achieve CR, his blasts were apparently sensitive to the therapy. In assessable cases in the literature where leukemic blasts were MPO-negative, myeloid marker-positive and B- and T-lineage marker-negative, CR was achieved in 54.5070 and 44.4070 with anti-acute myeloid leukemia therapy and anti-acute lymphocytic leukemia therapy, respectively. Five cases in the literature were treated with a chemothe- rapeutic regimen containing BHAC [or cytosine arabino- side (Ara-C)], DNR, and 6-MP, and all achieved CR. The regimen containing BHAC (or Ara-C), DNR, and 6-MP may be useful as induction chemotherapy for AML-M0. Key words: Minimally differentiated acute myeloid leuke- mia - Chemotherapy Correspondence to: K. Ogata, Third Department of Internal Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113, Japan Introduction Minimally differentiated acute myeloid leukemia (AML- M 0) is a recently established subtype of acute leukemia [12]. In 1991, The French-American-British (FAB) Co- operative Group proposed the following criteria for AML-M0: negative myeloperoxidase (MPO) and Sudan black B (SBB) reaction (or positive in less than 3070 of blasts), negative for B- and T-lineage markers, and posi- tive for myeloid markers (CD 13 and CD33) [4]. However, no optimal therapy for AMI~M 0 has been established to date. From January 1989 through December 1991, we followed five patients with AML-M0. The therapeutic results of these five patients and cases of AML-M0 reported in the literature are presented in this report. Patients and methods Diagnosis Based on the criteria proposed by the FAB group, a diagnosis of AML-M0 was made if leukemic blasts were negative for MPO and SBB reaction or positive in less than 3~ positive for CD 13 and/or CD33, and negative for all B- and T-lineage-specific markers (CD 3, CD 5, CD 10, CD 19). For immunophenotypic analysis, bone marrow mononuclear cells (BMMNC) were incubated with fluorescein-conjugated mouse anti-human monoclonal antibodies (MoAb), and fractions contain- ing more than 90% blasts were examined by flowcytometry (Coul- ter Epics CS). MoAb used were: T 11 (CD 2), T 3 (CD 3), T 1 (CD 5), 3A1 (CD7), J5 (CDI0), MY4 (CD14), B4 (CD19), B1 (CD20), MY7 (CDI3), MY9 (CD33), I2 (HLA-DR) (Coulter Immuno- logy), anti-platelet glycoproteins II b/III a (CD 41), and anti-glyco- phorin A (Cosmo Bio, Japan). A reaction was considered to be positive when more than 20% of the blasts showed fluorescence. Genomic DNA was isolated from BMMNC of two patients who had CD 2 and/or CD 7 positivity and was examined for human heavy-chain immunoglobulin (JH) and T-cell receptor (TCR) [}-chain gene rearrangements, as described previously [9]. Cryopreserved cells from the CD 2- and CD 7-positive patient were processed for transmission electron microscopy (TEM) according to standard techniques. MPO activity was examined by the method of Graham and Karnovsky [7].