Successful Autologous Peripheral Blood Stem Cell Transplantation In Severe Refractory Dermatomyositis
Authors: Saltarelli Francesca , D’Amelio Raffaele , Porrini Raffaele , Antonini Giovanni , Ferrari Antonella , Conte Esmeralda , Milanetti Francesca , Laganà Bruno , Antolino Giusy , Montefusco Enrico 
Published: October 2019

Abstract
Abstract 4507

Background.
Inflammatory myopathies are primary diseases of the striated muscles caused by an underlying autoimmune dysfunction. Dermatomyositis and polymyositis are the most common diseases of the striated muscle, skin and surrounding connective tissue. Usually the presentation includes proximal muscle weakness, inflammatory changes, creatine kinase elevation and skin rash. Although the cause of polymyositis/dermatomyositis is unknown, an autoimmune pathogenesis is strongly implicated and this provides the rationale for using immunosuppressant treatment. In the presteroid era prognosis was very poor, currently the mainstay treatment is based on high dose prednisone followed by different immunosuppressant and immunomodulating drugs as second and third line treatment for non responder patients. Autologous haemopoietic stem cell transplantation (HSCT) has been successfully employed in autoimmune diseases becoming a curative option for conditions with very poor prognosis, such as severe forms of systemic sclerosis, multiple sclerosis, and systemic lupus erythematosus. To our knowledge, 14 patients with polymyositis have been successfully treated with autologous bone marrow transplantation. The goal of PBSCT in polymyositis is to achieve remission of the systemic manifestations. Thus, we describe a case of dermatomyositis treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation (PBSCT), after a long history of conventional immunosuppressive therapy without advantage.

Aims and methods:
In our centre, member of the Rome Transplant Network, we observed a 60-year old man with seronegative dermatomyositis, which began in 1996 with symmetric proximal muscle weakness. Dermatomyositis was diagnosed according to Bohan and Peter criteria with a 5/5 score. Despite the administration of five lines of different immunosuppressive treatments between 1996 and 2010, disease progressed with pharingo-laryngeal involvement causing dysphagia and aphonia and EMG evidence of severe myopathic changes. HSCs were successfully mobilized with cyclophosphamide 2 g and G-CSF 5 mg/kg/day. Time from diagnosis to transplantation was 15 years. Tiothepa 70 mg on day -5 and cyclophosphamide 3.5 g on day -3 and -2 were administered intravenously as conditioning regimen followed on day 0 by reinjection of the cells collected by leukapheresis. The number of CD34+ cells infused was 2.9 × 106 /Kg. All the procedures for PBSCT were well tolerated and the post-transplantation period was uneventful, except for an episode of neutropenic fever without bacteriological documentation that resolved under broad-spectrum antibiotics.

Results.
After the PBSCT, we observed slow but progressive improvement in neurological symptoms and performance status. Currently, three months after transplantation, the patient is able to perform daily activities autonomously.

Conclusions.
Our case confirms the usefulness and safety of PBSCT in dermatomyositis. We are not able to tell which role high dosage of CSF have played in the clinical response. However our case reinforces the idea that PBSCT should be considered in the treatment of severe forms of dermatomyositis, even early during the disease course in order to reach the best response.

Disclosures:
No relevant conflicts of interest to declare.