5-Azacytidine increases fetal hemoglobin production in a patient with sickle cell disease.

5-Azacytidine, given to one sickle cell patient as 9 doses of 30 mg/m2 each at intervals of 8 hr, rapidly increased the number of red cells containing HbF (F cells), decreased the amount of HbS in F cells, and decreased the MCHC of F cells. Although a significant rise in the peripheral blood hemoglobin from 8 gm/dl to 10-12 gm/dl was obtained, painful vaso-occlusive crises continued to occur. Therapy was associated with no marrow toxicity, although erythroblastosis appeared after each course of therapy. Increased HbF production was associated with demethylation of two restriction enzyme sites 5' to the two gamma-globin genes. Five other restriction sites around the gamma-globin genes were unchanged. 5-Azacytidine is considered potentially mutagenic and carcinogenic in man and, therefore, further experimental treatment should be limited only to severely affected sickle cell patients.