Efficacy of danazol in pure red cell aplasia

Twenty-one unselected patients with refractory chronic anemias of various etiologies were treated with danazol, a synthetic attenuated androgen. All had previously failed treatment with hematinics, androgens, corticosteroids, high-dose intravenous immunoglobulin, antithymocyte globulin, cytotoxic immunosuppressive agents, and/or plasmapheresis. Three patients with pure red cell aplasia and one with aplastic anemia responded. No responses were observed in 11 patients with myelodysplastic syndromes, two patients with myelofibrosis, and two with paroxysmal nocturnal hemoglobinuria. Remission in pure red cell aplasia was maintained with danazol alone in one patient and required combined low-dose prednisone in two. Objective responses occurred in 2 to 3 weeks and therapy generally was well tolerated. To date, one patient with pure red cell aplasia remains in complete remission at 9 months on low-dose danazol alone. We conclude that danazol alone or combined with prednisone may induce and maintain remission in severe refractory pure red cell aplasia and possibly other chronic cytopenias characterized by immunologic marrow suppression. Further trials of danazol in treating these disorders are indicated.