A pilot study: Use of fludarabine for refractory dermatomyositis and polymyositis, and examination of endpoint measures

Objective. To study the effects of the adenine analog, fludarabine, on pati ents with refractory dermatomyositis and polymyositis, and to assess variab les used in following myositis patients during medical intervention. Methods. Patients whose myositis was not controlled by prednisone and at le ast one other immunosuppressive medication were entered into a pilot study during which they received 6 monthly cycles of intravenous fludarabine. Pat ients were assessed at baseline, every other month. and at month 7 for prim ary outcome measures of strength and function. Other measurements including peripheral blood cell subsets, muscle enzymes, and various assessments of disease activity were followed monthly during the fludarabine infusion peri od and for up to 6 months post therapy. Results. Of 16 patients who entered the study, 4 patients were classified a s improved, and 7 patients were classified as unchanged. Five patients who withdrew before month 7 were classified as treatment failures. Fludarabine caused a significant and prolonged lymphopenia without an increase in infec tious complications over that seen with other immunosuppressive agents used for myositis. A sudden death of one patient at the end of the study was no t thought to be drug related. Variables followed during the study emphasize d the distinction between patient functional improvement nt and disease rem ission. Conclusion. A subset of patients with refractory myositis may benefit from fludarabine therapy and controlled trials an indicated. Refinement and vali dation of variables useful for following myositis patients await larger stu dies.