title: Durability of the Rituximab Response in Acetylcholine Receptor Autoantibody-Positive Myasthenia Gravis.
abstract: OBJECTIVE
  Myasthenia gravis (MG), an autoimmune disorder of neuromuscular transmission, is treated by an array of immunotherapeutics, many of which are nonspecific. Even with current therapies, a subset of patients has medically refractory MG. The benefits of B-cell-targeted therapy with rituximab have been observed in MG; however, the duration of these benefits after treatment is unclear.
  
  
  OBJECTIVE
  To evaluate the durability of response to rituximab in the treatment of acetylcholine receptor autoantibody-positive (AChR+) generalized MG.
  
  
  METHODS
  This retrospective case series study included 16 patients with AChR+ MG referred to an MG clinic from January 1, 2007, to December 31, 2015. The patients were treated with rituximab and followed up for 18 to 84 months after treatment.
  
  
  METHODS
  Assessment of long-term clinical response, durability of response and/or relapse rate, AChR autoantibody levels, adverse effects, and inflammatory markers.
  
  
  RESULTS
  In the 16 patients (6 men and 10 women; median age, 42 [range, 18-69] years), clinical improvement was observed in parallel with complete withdrawal or reduction of other immunotherapies, with all patients achieving complete stable remission, pharmacologic remission, or minimal manifestations based on the Myasthenia Gravis Foundation of America postintervention status criteria. Nine patients (56%) had a relapse during a mean follow-up of 36 (range, 24-47) months. Seven patients (44%) remained relapse free with a mean follow-up of 47 (range, 18-81) months since the last rituximab treatment. All values were normalized to a pretreatment anti-AChR antibody level of 100% and the mean levels after each rituximab cycle were calculated. A 33% decrease was seen after cycle 1 of rituximab treatment (100% vs 67%; P = .004); 20% after cycle 2 (compared with cycle 1) (67% vs 47%; P = .008); and 17% after cycle 3 (compared with cycle 2) (47% vs 30%; P = .02). However, the serum cytokine levels measured were found to be unchanged.
  
  
  CONCLUSIONS
  Rituximab therapy appears to be an effective option in patients with refractory AChR+ MG, who were observed to have a durable response after treatment. Identification of markers of disease relapse and sustained remission are critical next steps in the development of pathophysiology-relevant, evidence-based practice parameters for rituximab in the treatment of MG.
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Kimberly R
authors.initials: KR
authors.lastname: Robeson
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Aditya
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Benison
authors.initials: B
authors.lastname: Keung
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: DiCapua
authors.affiliation: Department of Neurology, Hospital for Special Surgery, New York, New York.
authors.forename: Emily
authors.initials: E
authors.lastname: Grodinsky
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Huned S
authors.initials: HS
authors.lastname: Patwa
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Panos A
authors.initials: PA
authors.lastname: Stathopoulos
authors.affiliation: Department of Neurology, Hospital for Special Surgery, New York, New York.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Goldstein
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: O'Connor
authors.affiliation: Program in Clinical and Translational Neuromuscular Research, Division of Neuromuscular Medicine, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Nowak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000097:blood* / Q000188:drug therapy* / Q000276:immunology; D040901:Proteomics / Q000379:methods; D011950:Receptors, Cholinergic / Q000276:immunology*; D012189:Retrospective Studies; D000069283:Rituximab / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D007155:Immunologic Factors; D011950:Receptors, Cholinergic; D000069283:Rituximab