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 × 10(9)/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.

Anemia and thrombocytopenia are frequent clinical manifestations of myelofibrosis as well as important prognostic factors of the disease. Concerning the treatment of anemia, the first step should be the correction of reversible contributing factors, such as possible iron, folate and vitamin B12 deficiency. Then, treatment options include erythropoiesis stimulating agents, androgens, immunomodulating drugs, corticosteroids, and splenectomy. Anemia responses may also be observed in some patients treated with JAK inhibitors. However, most patients eventually fail to such therapies and become transfusion dependent. Some of the aforementioned therapies can also improve thrombocytopenia, but the responses are usually observed in patients with moderate platelet count decrease. Allogeneic hematopoietic stem cell transplantation, the only curative treatment of myelofibrosis, can be an alternative for selected patients with cytopenias who are refractory to conventional therapies. However, for the majority of patients, the management of anemia and severe thrombocytopenia remains an unmet need.