TY - JOUR
T1 - Rituximab therapy for myopathy associated with anti-signal recognition particle antibodies
T2 - A case series
AU - Valiyil, Ritu
AU - Casciola-Rosen, Livia
AU - Hong, Grace
AU - Mammen, Andrew
AU - Christopher-Stine, Lisa
PY - 2010/9
Y1 - 2010/9
N2 - Objective. The myopathy associated with anti-signal recognition particle (anti-SRP) is a severe necrotizing immunemediated disease characterized by rapidly progressive proximal muscle weakness, markedly elevated serum creatine kinase (CK) levels, and poor responsiveness to traditional immunosuppressive therapies. Reports on the efficacy of B cell depletion therapy for anti-SRP-associated myopathy are mixed. We describe 8 patients with anti-SRP-associated myopathy and their response to treatment with the anti-CD20 monoclonal antibody rituximab. Methods. We identified 8 patients with myopathy who tested positive for anti-SRP antibodies by immunoprecipitation and were treated with rituximab as part of clinical care. We reviewed their medical records to assess clinical, serologic, and histologic characteristics and response to therapy. In 5 patients, serum was collected before and after rituximab therapy. Autoantibodies were detected by immunoprecipitation and quantitated by densitometry, and the percent decreases in anti-SRP autoantibody levels were calculated. Results. Six of 8 patients who had been refractory to standard immunosuppressive therapy demonstrated improved manual muscle strength and/or decline in CK levels as early as 2 months after rituximab treatment. Three patients sustained the response for 12-18 months after initial dosing. All of the patients were continued on adjunctive corticosteroids, but doses were substantially reduced after rituximab. Quantitative levels of serum anti-SRP antibodies also decreased after rituximab treatment. Conclusion. B cell depletion therapy with rituximab is effective for patients with myopathy associated with anti-SRP. The substantial decrease in anti-SRP antibody levels after rituximab treatment also suggests that B cells and anti-SRP antibodies may play a role in the pathogenesis of this myopathy.
AB - Objective. The myopathy associated with anti-signal recognition particle (anti-SRP) is a severe necrotizing immunemediated disease characterized by rapidly progressive proximal muscle weakness, markedly elevated serum creatine kinase (CK) levels, and poor responsiveness to traditional immunosuppressive therapies. Reports on the efficacy of B cell depletion therapy for anti-SRP-associated myopathy are mixed. We describe 8 patients with anti-SRP-associated myopathy and their response to treatment with the anti-CD20 monoclonal antibody rituximab. Methods. We identified 8 patients with myopathy who tested positive for anti-SRP antibodies by immunoprecipitation and were treated with rituximab as part of clinical care. We reviewed their medical records to assess clinical, serologic, and histologic characteristics and response to therapy. In 5 patients, serum was collected before and after rituximab therapy. Autoantibodies were detected by immunoprecipitation and quantitated by densitometry, and the percent decreases in anti-SRP autoantibody levels were calculated. Results. Six of 8 patients who had been refractory to standard immunosuppressive therapy demonstrated improved manual muscle strength and/or decline in CK levels as early as 2 months after rituximab treatment. Three patients sustained the response for 12-18 months after initial dosing. All of the patients were continued on adjunctive corticosteroids, but doses were substantially reduced after rituximab. Quantitative levels of serum anti-SRP antibodies also decreased after rituximab treatment. Conclusion. B cell depletion therapy with rituximab is effective for patients with myopathy associated with anti-SRP. The substantial decrease in anti-SRP antibody levels after rituximab treatment also suggests that B cells and anti-SRP antibodies may play a role in the pathogenesis of this myopathy.
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U2 - 10.1002/acr.20219
DO - 10.1002/acr.20219
M3 - Article
C2 - 20506493
AN - SCOPUS:77956398538
SN - 2151-4658
VL - 62
SP - 1328
EP - 1334
JO - Arthritis Care and Research
JF - Arthritis Care and Research
IS - 9
ER -