CHARACTERISTICS AND OUTCOME OF PATIENTS WITH ACUTE LYMPHOCYTIC-LEUKEMIA AND MYELOPEROXIDASE-POSITIVE BLASTS BY ELECTRON-MICROSCOPY

The purpose of the study was to analyze the clinical and laboratory ch aracteristics of patients with acute lymphocytic leukemia (ALL) who ex hibited myeloperoxidase-positive blasts by electron microscopy (EM-MPO -positive), and assess their response to therapy and their prognosis. Since 1988, 21 adults with newly-diagnosed ALL and EM-MPO-positive bla sts were referred to our service. In addition to documentation of thei r clinical and hematopathologic characteristics, patients underwent cy togenetic, immunophenotypic, molecular, and electron-microscopic evalu ations. Twenty patients were treated with the vincristine-Adriamycin-d examethasone (VAD) regimen, and one patient was induced with amsacrine and high-dose cytosine arabinoside (ara-C). The 21 patients were amon g 141 patients with ALL (15%) seen during the same period. Their media n age was 46 years (Pange 15 to 77 years). The immunophenotype was T-c ell ALL in 12 patients (57%). Karyotypic studies did not demonstrate s pecific recurrent abnormalities. The median percentage of EM-MPO-posit ive blasts was 15% (range 3% to 45%). Eighteen patients (85%) had high -risk ALL. With induction chemotherapy 15 of 20 (75%) receiving VAD th erapy achieved a complete remission (CR). However, the median CR durat ion was 18 months, and the median survival was 18 months with a 3-year disease-free survival rate of 25%. There were eight relapses and one lineage switch to acute myelogenous leukemia (AML). Patients with ALL and EM-MPO-positive disease are a unique subgroup with long-term poor prognosis on conventional anti-ALL therapy, and may benefit from inten sification treatments with agents effective against AML.