Hydroxyurea increases hemoglobin F levels and improves the effectiveness of erythropoiesis in β-thalassemia/hemoglobin E disease

Hydroxyurea (HU) is one of several agents that have been shown to enhance hemoglobin (Hb) F levels in patients with sickle cell disease and may be useful as e therapy for β-globinopathies. However, limited information exists on the effects of HU in patients with thalassemia. Accordingly, we examined the hematologic effects of orally administered HU in 13 patients with β-thalassemia/Hb E, including four patients who had been splenectomized. These patients were treated with escalating doses (final range, 10 to 20 mg/kg/d) for 5 months and were observed in the outpatient hematology clinic every 2 to 4 weeks. Complete blood counts including reticulocyte counts, amounts of Hb E and Hb F, (G)γ:(A)γ and α:non-α globin biosynthetic ratios were evaluated before and during treatment. Almost all patients responded with an average increase of 33% in Hb F levels, from a mean (±SD) of 42% ± 11% to 66% ± 8% (P < .0001), and a reciprocal decline in the percentage of Hb E from 59% ± 9% to 49% ± 8% (P < .001). Reticulocytosis was decreased from a mean (±SD) of 18.0% ± 15.6% to 11.7% ± 9.1% (P < .05); there was also a slight (10%) but statistically significant increase in hemoglobin levels and an improved balance in α:non- α globin chains ratios. The side effects were minimal in most patients, although these patients tended to tolerate a lower dose of HU before significant myelosuppression than has been our previous experience in sickle cell disease. One splenectomized patient died of sepsis during the trial. We conclude that increased Hb F production β-thalassemia/Hb E patients, with an improvement in the α:non-α globin ratios and, probably, the effectiveness of erythropoiesis, can be achieved using HU. Longer trials of HU in this population, including at other doses and in combination with other agents, appear warranted.