[Is 1,25(OH)2D3 effective in chronic osteomyelofibrosis?]

1,25-dihydroxycholecalciferol (1,25[OH]2D3) is the most important active metabolite of vitamin D3 and has a remarkable antiproliferative effect on megakaryocytes in vitro. It may have a favorable influence on collagen formation and degradation by a megakaryocyte/monocyte dependent modulation. We evaluated the clinical effect of 1,25(OH)2D3 in four patients suffering from idiopathic myelofibrosis. The daily dose ranged from 0.006 to 0.016 microgram/kg. One patient died from asthenia 2.5 months after starting treatment and three were observed for more than a year. Despite treatment with 1,25(OH)2D3, they all needed regular transfusions. During follow-up bone marrow biopsies did not reveal a decrease in fibrosis.