A Phase 2 interventional study of Panzyga IVIG and Placebo in Small Fiber Neuropathy, Autoimmune Small Fiber Neuropathy and Inflammatory Polyneuropathy, sponsored by Endeavor Health. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-01-09.
Sponsored by Endeavor Health · Phase 2, Interventional, and Treatment
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.
Small fiber neuropathy (SFN) is an increasingly prevalent diagnosis in neurology and neuromuscular centers. Modern diagnostic techniques, including skin biopsies and autonomic nervous testing are helping to find SFN in many patients with undiagnosed pain syndromes including fibromyalgia. The prevalence is rising for SFN, and an immune etiology may underlie 19%-34% of cases. While there is no standard of care treatment, current treatment strategies for SFN include long-term steroid therapy which come with a host of side effects. 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, as well as improving validated questionnaire scores monitoring symptom burden and disability. However, neither IVIG nor any other immunosuppressant has been studied in a sufficiently powered and adequately dosed controlled, randomized clinical trial to demonstrate efficacy.
Exclusion Criteria:
Patients in the treatment arm will receive 2g/kg IVIG every 4 weeks (over 2 days, 1g/kg dose on Day 1 and 1g/kg dose on Day 2) for 24 weeks (6 doses total).
Drug: Panzyga IVIG
Patients in the placebo arm will receive 0.9% NaCl infusions on the same schedule as the active treatment group (Day 1 and Day 2 every 4 weeks for 24 weeks total, (6 doses).
Drug: Placebo
Immune Globulin Infusion 10% (Human)
0.9% NaCl prepared as the calculated dose equivalent volume to IVIG.
quantified change in intraepidermal nerve fiber density (IENFD)
3mm skin punch biopsy at 3 sites
Time frame: Week 24
Change in visual analogue pain scale responses
Self-reported pain intensity on a scale of 0-10 using the Wong-Baker FACES Pain Rating Scale, with 0 being no pain and 10 being pain as bad as can be
Time frame: baseline and Week 28
Change in Small Fiber Neuropathy-Rasch Overall Disability Scale (SFN-RODS) score
The SFN-RODS is a 32-item scale measuring disability in daily activities. Scores range from 0 - 64, with a lower score correlating with worse disease
Time frame: baseline and Week 28
Change in Small Fiber Neuropathy-Symptom Inventory Questionnaire (SFN-SIQ) score
The SFN-SIQ is a validated 13-item scale measuring various SFN and autonomic symptoms. Scores range from 0 -39, with a higher score correlating with more severe disease.
Time frame: baseline and Week 28
Change in Utah Early Neuropathy Scale (UENS) examination scores
The UENS is a validated physical exam score from 0-42 points to look for small fiber neuropathy. It includes measures of sensation, reflexes, and strength in both lower extremities. A higher score indicates increased impairment.
Time frame: baseline and Week 28
Plan to share: No
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