Efficacy and Mechanism of Action of SCIg in Patients With Stiff Person Syndrome (SPS)

Efficacy and Mechanism of Action of SCIg in Patients With Stiff Person Syndrome

This is a pilot, proof-of concept investigator-initiated trial planned for 22 patients with the diagnosis of Stiff Person Syndrome (SPS). The study will compare efficacy of treatment using subcutaneous immunoglobulin therapy (SCIg) compared to intravenous immunoglobulin (IVIg) therapy. The majority of IVIg naïve subjects (those not already receiving IVIg) are typically managed with non-immunotherapy mostly Gamma Aminobutyric Acid (GABA) -enhancing drugs such as Baclofen or Diazepam.

Study Design:This is a proof of concept observational prospective, open label, study on the safety, efficacy and convenience of treatment with SCIg study of 22 patients at Thomas Jefferson University Hospital. Two cohorts of patients within the total of 22 will be included; half of them (11 patients) currently receiving and responding to IVIg and the other half starting de novo on SCIg. Patients diagnosed with SPS according to defined sets of symptoms will be eligible to enroll.

The primary clinical outcome will be based on clinical efficacy measures, as used before for the IVIg trial, based on changes in the Stiffness Index and Heightened Sensitivity scores, using the validated scales that the investigators have had previously utilized and validated (Dalakas et al 2001; see attached at the end of the protocol). These same measurements will be applied while on IVIg (weeks 0, 4, 8, 12) and will be compared to the measurements obtained during SCIg (weeks 16, 20, 24, 28). The secondary outcome will be Quality of Life (QoL) responses and patient preference for each treatment.

Inclusion Criteria:

• Men or women aged >18 years
• Diagnosis of SPS based on standard criteria
• IVIg Group: Receiving the equivalent of 1-2 g/kg IVIg every 4 weeks with dependence* on IVIg to maintain clinical response *Dependence is clinically determined either by symptomatic worsening of condition at the end of the inter-dose interval or by worsening after dose reduction or discontinuation within the previous 3 months.
• IVIg-Naïve Group: Patients with symptomatic SPS and never treated with IVIg (IVIg-naïve group), poorly controlled with standard therapy

Exclusion Criteria:

• Pregnancy, planned pregnancy, breast-feeding or unwillingness to practice contraception
• Severe concurrent medical conditions, which would prevent treatment or assessment, including significant hematological, renal or liver dysfunction or malignancies
• Initiation of immunomodulatory treatment other than IVIg in the past 3 months
• Participation in a trial of an investigational medicinal product in the past 12 weeks
• Presence of any medical condition, which in the opinion of the investigator might interfere with performance or interpretation of this study.