CLINICAL ASPECTS OF ACUTE MYELOID LEUKEMIAS OF THE FAB TYPE-M3 AND TYPE-M4EO

Acute promyelocytic leukemia (AML FAB M3, APL) and acute myelomonocyti c leukemia with abnormal eosinophils (AML M4Eo) are considered distinc t entities with characteristic clinical, morphological, cytogenetic, a nd prognostic features. Promyelocytic leukemia is characterized by abn ormal promyelocytes replacing normal hematopoiesis associated with a t ranslocation between the long arms of chromosomes 15 and 17 t (15; 17) , severe coagulopathy and responsiveness to all-trans retinoic acid (t retinoin). Characteristic features of AML M4Eo are a myelomonocytic ma rrow infiltration, eosinophils with abnormal immature granules positiv e for chloroacetate esterase, an inversion or translocation of chromos ome 16, and an increased risk of meningeal relapses. Prognosis of both types of AML has been reported to be better than prognosis of the oth er entities combined. Since most of the published data were collected from heterogeneous patient populations treated with various chemothera peutic regimens, we have analyzed treatment outcome of AML M3 and M4Eo in the AMLCG-85 study for patients younger than 60 years. For the tot al population of 594 patients of this study, CR rate was 68.89%, early death rate 11.60%, and no or partial remission was achieved in 19.51% of the cases. Of 40 patients with AML M3 or M3 v complete remission w as attained in 62.5%. Nine patients died within 42 days after the star t of antileukemic therapy (22.5%). Of these nine, four died because of infection, five because of bleeding. Relapse-free survival rate was 5 9% after 3 years, significantly better than the respective curve of th e other FAB types combined (35% after 3 years). In AML M4Eo, 91.7% of the 24 patients reached complete remission. The early death rate was 8 .3%. No case of nonresponse was seen. Relapse-free survival rate was 4 9% after 3 years compared with 35% for the other types combined.