Background: Polymyositis and especially anti SRP positive patients are difficult to treat and treatment options are limited. Patients suffer from progressive muscle weakness and disability.
Objectives: To find new therapeutical options for a treatment resistant patient
Methods: A 32 year old patient presented in September 2000 with progressive muscle weakness, weight loss and high creatine kinase (CPK) levels (3601 U/l, normal range: 0-190 U/l). MRI of his thighs showed typical edematous swelling of the flexor and adductor muscles and a lipomatous atrophia of the extensors. The muscle biopsy confirmed the diagnosis of a necrotizing myopathy. During the next months glucocorticosteroids, methotrexate, azathioprine, cyclosporine A, cyclophosphamide pulses and mycophenolate mofetil were ineffective, even in combination. The patient had persistent myalgia, muscle weakness and highly elevated CPK levels, he was bound to a wheel chair 2 years after diagnosis.
Although a newly gained muscle biopsy in 12/2003 showed an over expression of TNF-alpha the TNF-antagonist Infliximab did not stop disease progression. Newer therapeutical approaches with Alemtuzumab, a anti-CD 52 lymphocyte antibody, had no beneficial effect neither. In April 2005 a myeloablation with cyclophosphamide (120mg/kg bodyweight) and total body irradiation (12 Gy) with a subsequent reinfusion of CD34+ selected autologous stem cells was performed. Stem cells had been collected after a mobilization treatment with 2x2g cyclophosphamide and granulocyte colony-stimulating factor (G-CSF) in October 2002.
Results: After the autologous stem cell transplantation muscle strength gradually improved. The CPK levels which since the diagnosis always had been elevated normalized (03/2006: CPK 133 U/l). A whole body MRI proved remission of myositis. There were only minor infectious compilcations and the patient is in complete remisison without any further treatment since May 2005.

Conclusion: This is the first report on a successful autologous peripheral blood stem cell transplantation in a patient with treatment resistant anti-SRP positive polymyositis. Myeloablative therapy for conditioning was the escalation after ineffective lymphoablation with regular dose cyclophosphamide and Alemtuzumab. Dose escalating of non-effective regimes would only increase the toxicity but not the efficacy.