Rituximab in the treatment of dermatomyositis: an open-label pilot study.
OBJECTIVE
To test the hypothesis that B cells play a role in the pathophysiology of dermatomyositis (DM) by examining the effect of B cell depletion in patients with symptomatic DM. Patients were treated with rituximab, a CD20+ B cell-depleting monoclonal antibody.


METHODS
This was an open-label uncontrolled pilot trial in 7 adult patients with DM, 6 of whom had longstanding illness that was responding inadequately to a number of currently available immunosuppressive agents. All patients received 4 intravenous infusions of rituximab given at weekly intervals. Patients were followed up for up to 1 year without further treatment with rituximab. One patient was lost to followup. The principal efficacy outcome was muscle strength, measured by quantitative dynomometry.


RESULTS
All 6 evaluable patients exhibited major clinical improvement, with muscle strength increasing over baseline by 36-113%. Maximal improvements in muscle strength occurred as early as 12 weeks after the initial infusion of rituximab. CD20+ B cells were effectively depleted in all patients by 12 weeks. Four patients experienced a return of symptoms that coincided with the return of B cells before the 52-week end point. Two patients maintained their increased muscle strength at 52 weeks, and 1 of these patients maintained this strength even after the return of B cells. Other symptoms of DM, including rash, alopecia, and reduced forced vital capacity, improved markedly in patients with these symptoms. Rituximab was well tolerated, with no treatment-related severe or serious adverse events during the observation period of this study.


CONCLUSIONS
This small open-label study of DM patients treated with rituximab provided sufficiently encouraging results to justify a more formal evaluation of the value of B cell depletion therapy in the treatment of DM.
Levine
Todd D
TD
Phoenix Neurological Associates, Phoenix, Arizona 85006, USA. LEVINE865@aol.com
D000328:Adult; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000032:analysis; D001402:B-Lymphocytes / Q000502:physiology; D003882:Dermatomyositis / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D010865:Pilot Projects; D000069283:Rituximab; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000069283:Rituximab