Intravenous Immunoglobulin (IVIG) in the Treatment of Small Fiber Neuropathy Due to TS-HDS, FGFR-3, or Plexin D1 Antibodies: a Double Blinded Placebo-controlled Phase II Trial
This study will enroll patients with small fiber neuropathy (SFN). The study will look at an intravenous immunoglobulin (IVIG) called Panzyga. Panzyga is approved by the FDA as a therapy for Primary humoral immunodeficiency (PI) in patients 2 years of age and older; Chronic immune thrombocytopenia (ITP) in adults and Chronic inflammatory demyelinating polyneuropathy (CIDP) in adults. It has not been approved by the FDA for use in SFN. There is mounting evidence that Intravenous Immunoglobulin (IVIG) can cause pain reduction and improve objective nerve fiber densities on skin biopsies in great numbers in SFN patients. The primary outcome is quantified improvement in intraepidermal nerve fiber density (IENFD) on repeat skin punch biopsy after 6 months of IVIG treatment.
• Patients ≥ age 18
• Patient with clinical and biopsy evidence of pure small fiber neuropathy (with or without dysautonomia) as evidenced by reduced IENFD on skin biopsy using PGP 9.5 as the immunostain. Biopsy must have been performed within 12 months of study enrollment. If biopsies were not done at CRL, they will be repeated and done at 3 sites (upper and lower thigh, lower calf), to have consistent and equivalent biopsy data with the follow up biopsy done after 6 mos of treatment
• Patients must have elevated and/or abnormal titers of autoantibodies to TS-HDS-IgM, FGFR3-IgG, or Plexin-D1 measured by the Washington University Neuromuscular Laboratory (St Louis) within 12 mos of enrollment
• Patients must have a baseline pain score on a visual analogue scale (VAS) of Greater or equal to 4/10
• Patients must have a baseline Utah Early Neuropathy Scale (UENS) score of Greater or equal to 4/10
• Small Fiber Neuropathy Screening List (SFNSL) score of 11/84 or greater
• Non-pregnant, non-lactating female. Females of reproductive potential must use 2 forms of contraception or continuously abstain from heterosexual sex during treatment