Alteration of blast phenotype after low-dose cytarabine in children with acute myeloid leukemia.
Two children with acute myeloid leukemia (FAB M1 and M2) experienced bone marrow relapse during maintenance chemotherapy 7 and 10 months after diagnosis. Low-dose ARA-C monotherapy (2 X 10 mg/m2 per day s.c. for 14 days) was then initiated, as suggested by others reporting induction of differentiation and achievement of remission without toxic side effects. In contrast to these reports, remission induction was not observed in the two children after low-dose ARA-C but was achieved by subsequent high-dose chemotherapy. However, blast cell characteristics revealed some alterations. Blast count and chromosome pattern remained unchanged. Cytochemistry revealed the appearance of esterase- (0----11%), 0----21%) and PAS- (0----74%, 0----45%) positive cells in the patients and a remarkable increase (patient 1: 0----71%) and decrease (patient 2: 90----12%) in acid phosphatase positivity. Expression of myeloid marker VIM D5 decreased distinctly (70----4%, 77----11%). However, the biologic relevance of these alterations remains in question. The failure to respond clinically to low-dose ARA-C in both children is discouraging.
D000950:Antigens, Ly / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D001853:Bone Marrow / Q000276:immunology; D002648:Child; D003561:Cytarabine / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000276:immunology; D010641:Phenotype; D013601:T-Lymphocytes / Q000276:immunology
D000950:Antigens, Ly; D000954:Antigens, Surface; D003561:Cytarabine