Objective: -the efficacy of the anti-CD20 antibody, Rituximab, in the treatment of patients with Stiff-person syndrome

Background: SPS is a rare autoimmune progressive disorder of the central nervous system(CNS). Symptoms are stifness and painful extensor spasms. Stifness affects the thoracolumbar paraspinal muscles,arms and legs,it has insidious onset;it appears in 3rd decade of life,without trigger infections.The diagnostic is based on clinical signs and sustained by electromyography (EMG) and high serum and cerebrospinal fluid titres of antibodies against acid decarboxylase (GAD).EMG shows the muscle stifness is produced by involuntary co-contraction of motor units,resembling a normal voluntary contraction in needle EMG-recordings [figure 1].Rituximab has recently been proposed to modulate B-cells activity in CNS in SPS.

Methods: Twenty anti-GAD antibody positive patients were randomised to receive Rituximab or placebo for 4 months.Ten patients received Rituximab intravenously(375mg/^m2) and ten received placebo (saline solution and human albumin-Flexbumin 0,4 mg/ml).After the washout,the patients crossed the alternative therapy for another 4 months.Efficiency was sustained by the titer of anti-GAD antibodies and clinical signs.Direct therapy effect was compared for both groups.The patients didn’t smoke or drink alcohol.

Results: In the group with Rituximab-randomised patients,the anti-GAD antibodies decreased significantly from month one through four:7 patients (70%) had a low titer of antibodies.The scores in placebo-randomised group were the same from month 1 to 4 and declined when they crossed to Rituximab therapy.

Conclusions: The anti-GAD antibodies declined after Rituximab,but not after placebo.Our clinical succesful utilisation of a monoc

onal anti-B cell antibody treatments leads to the conclusion that SPS is a B cell mediated autoimmune disease.

References: 1.Dalakas MC,Fujii M,Li M,Mc Elray B.The clinical spectrum of anti-GAD antibody-positive patients with stiff-person syndrome.

2.Levy LM,Dalakas MC,Floeter MK.The stiff-person syndrome:an autoimmune disorder affecting neurotransmission off gamma-aminobutyric acid.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/immunomodulatory-therapy-in-stiff-person-syndrome-sps-a-controlled-rituximab-randomised-study/