Safety and efficacy of thalidomide in patients with myelofibrosis with myeloid metaplasia

We administered the anti-angiogenic drug thalidomide to 21 patients (12 men ) with myelofibrosis with myeloid metaplasia (MMM), who were not responsive to standard treatment. Patients received thalidomide at an escalating dose from 100 to 400 mg/d. Administration of the drug was discontinued before t he planned 6 months of treatment in 19 patients (90.5%), mainly because of somnolence and/or fatigue, neurological symptoms or neutropenia. Of the 13 evaluable patients (who received more than 30 d of therapy), anaemia improv ed in three out of seven (43%) who were treated because of anaemia; thrombo cytopenia improved in two out of three (66.6%) who were treated because of thrombocytopenia; splenomegaly was reduced in four (30.8%). Undesired incre ases in white blood cell and platelet counts were observed in three (23.1%) and five (38.5%) patients respectively. A severity score, indexed on haema tological and clinical parameters, improved in two patients (15.4%), but wo rsened in five (38.5%). In conclusion, standard-dose thalidomide in MMM pat ients is burdened with a high rate of side-effects, which prevent prolonged treatment. Because the drug is effective in improving anaemia and thromboc ytopenia and in reducing splenomegaly, low-dose therapy warrants evaluation . The unexpected observation of leucocytosis and thrombocytosis suggests bi ological studies and better criteria for selection of patients for treatmen t.