Danazol therapy for the anemia of myelofibrosis: assessment of efficacy with current criteria of response and long-term results

The efficacy of danazol was assessed in 50 patients with myelofibrosis and anemia using the recently revised criteria of the International Working Group for Myelofibrosis Research and Treatment. According to them, anemia response (clinical improvement) is defined as transfusion cessation in transfusion-dependent patients or an Hb increase >2 g/dl in patients without transfusion requirements, both maintained for at least 12 weeks. Median follow-up from danazol start was 36 months (interquartile range [IQR] 19.2–58.8). Anemia response was achieved in 15 patients (30 %), including 5 of the 27 with transfusion dependency (18.5 %) and 10 of the 23 without transfusion requirements (43.5 %). Median time to response was 5 months (IQR 4–7) and median duration of the response 14 months (IQR 10–21). Among responder patients, 5 discontinued therapy due to toxicity or personal decision and 1 died from spleen rupture while being in response. A trend for worse response was seen in transfusion-dependent patients (p = 0.055). A platelet increase >50 × 10⁹/l was observed in 3 of 13 thrombocytopenic patients, all of whom had moderate thrombocytopenia. Toxicity was usually moderate, leading to treatment withdrawal in only 4 patients. Danazol is effective in 30 % of patients with anemia-associated myelofibrosis. The responses are less frequent in patients with transfusion dependency.