Danazol

Danazol is a synthetic androgen licensed since the 1970s for endometriosis, fibrocystic breast disease and hereditary angioedema. In haematology it is used off-label for the anaemia of myelofibrosis and myelodysplastic syndromes and for immune and aplastic cytopenias, where about a third of patients improve; it also lengthens telomeres in telomere-biology disorders.

In the phase 3 MOMENTUM trial in symptomatic, anaemic myelofibrosis previously treated with a JAK inhibitor, danazol was the active comparator: 25 percent of patients on momelotinib had their symptom score halve against 9 percent on danazol, and more became transfusion independent. Liver toxicity, virilisation and thrombosis limit its use. The primary myelofibrosis page names it among the treatments for anaemia.