Danazol treatment of idiopathic myelofibrosis with severe anemia

Severe anemia is an important problem in patients with idiopathic myelofibrosis (IM). When other therapeutic measures are unsuccessful or not applicable, 40-50% favorable responses are obtained with androgen therapy. Oxymetholone is the drug usually employed, but good results have also been reported with danazol, although the experience is limited to a few patients. The aim of the present study was to evaluate the effect of danazol on the anemia of IM.

Seven out of 22 consecutive IM patients were eligible for danazol treatment because of severe anemia not treatable with (four cases) or refractory to (three cases) other therapies. Danazol (600-800 mg/day) was given orally for six months and thereafter progressively tapered to the minimum effective dose in responding patients or discontinued in non-responders. Complete response was considered cessation of transfusion requirements with normalization of hemoglobin (Hb) values; partial response was defined as a > 30% reduction in transfusional needs or an increase > 10 g/L in the Hb. The effect on platelet counts was also analyzed.

One patient splenectomized three years earlier achieved a complete response and three a partial response, giving an overall response rate of 57 %. A significant increase in platelet counts was also observed in three responders. The responses were first seen between three and six months after the start of treatment, which was usually well tolerated.

Danazol, given at an appropriate dosage for a sufficient time, is an effective treatment for a substantial proportion of IM patients with severe anemia without marked splenomegaly or who have been previously splenectomized.