Efgartigimod for Stiff Person Syndrome (ESPS) (ESPS)

The goal of this clinical trial is to examine the proportion of patients with stiff person syndrome with no worsening in stiffness and/or spasms while on efgartigimod-hyaluronidase (EFD) when compared to their current treatment. The main questions it aims to answer are:

• proportion of patients with stiff person syndrome with no worsening in DSI and HSS scores
• whether there are changes in laboratory values, vital signs, electrocardiogram, or depression, and suicide risk during the trial, as well as the incidence of any adverse events.

Participants will come to the clinic up to 18 times and have up to 5 phone call visits during the course of the trial. During these visits a variety of measures will be collected, including blood samples, neurological and physical exams, patient reported outcomes on stiffness, spasms, depression, and suicide risk.

Study Overview

• Status: Not yet recruiting
• Conditions: Stiff-Person Syndrome
• Intervention / Treatment: Biological: Efgartigimod

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Tuan H Vu, MD; Phone Number: 813-974-9413; Email: tvu6@usf.edu
• Study Contact Backup: Name: Jessica D Shaw, MPH; Phone Number: 813-974-9413; Email: jessshaw@usf.edu

Study Locations

• United States
  • Florida
    • Tampa, Florida, United States, 33612
      • University of South Florida, Carol and Frank Morsani Center for Advanced Healthcare
      • Contact: Jessica D Shaw, MPH; Phone Number: 813-974-9413; Email: jessshaw@usf.edu
      • Principal Investigator: Tuan H Vu, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age 18-80, men and women, capable of giving informed consent.
2. Must have unexplained stiffness of limb and axial (trunk) muscles and involuntary striated muscle spasms.
3. DSI and HHS must be >=2 (to allow for detection of improvement).
4. Presence of serum (or CSF) anti-GAD antibodies regardless of titers.
5. Stable dosage for at least two months before screening visit with antispasmodics (muscle relaxants, benzodiazepines, baclofen).
6. Women with children bearing potential must be willing to use highly effective contraception method during and for a minimum of 90 days after the last dose of IP.

Exclusion Criteria:

1. Exclusionary conditions:

1a. type 1 DM

1b. Cancer, except basal cell skin cancer

1c. Infections: HIV, Hepatitis B or C, clinically significant active infection not sufficiently resolved in the investigator's opinion

1d. Serum IgG (<6 g/L) at screening

1e. pregnancy/breast feeding. 2. Exclusionary medications: rituximab within 6 months of screening. 3. IVIG or PLEX treatment 4 weeks prior to screening. 4. History of any type of solid organ or bone marrow transplant.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: subcutaneous Efgartigimod-hyaluronidase (EFG); Participants with GAD65-antibody positive SPS will be given subcutaneous Efgartigimod-hyaluronidase (EFG).	Biological: Efgartigimod; Efgartigiomd-hyaluroidase (EFG) is a neonatal Fc receptor (FcRn) inhibitor, which blocks the recycling of Immunoglobulin G (IgG), including pathogenic IgG

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Distribution of Stiffness Index (DSI)	DSI is a validated indicator or stiffness. Scores range from 0 to 6 and reflect the extent of stiffness. One point is given for stiffness in each of the following areas: lower trunk, upper trunk, legs, arms, face and abdomen.	From enrollment to the end of treatment at week 13
heightened sensitivity score (HSS)	HSS measures changes in the frequency of spasms. Scores range from 1 to 7; one point given for each source or type of spasm: unexpected noises, visual stimuli, somatosensory stimuli, voluntary activities, emotional upset or stress, no specific stimuli, or nocturnal spasms.	From enrollment to end of treatment at week 13

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of patients with SPS who are treatment responders	Proportion of patients with SPS who are treatment responders, defined as: >= 2 points reduction in the distribution of stiffness index (DSI) AND >= 1 point reduction in heightened sensitivity score (HSS)	enrollment to end of 13 weeks
The duration of time patients maintain responder status	A responder is defined as one having >= 2 points reduction in the distribution of stiffness index (DSI) AND >= 1 point reduction in heightened sensitivity score (HSS)	from enrollment to end of treatment at week 13
Modified Rankin Scale		From enrollment to end of treatment at week 13

Collaborators and Investigators

• Sponsor: University of South Florida
• Investigators: Principal Investigator: Tuan H Vu, MD, University of South Florida

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: July 25, 2024
• First Submitted That Met QC Criteria: July 25, 2024
• First Posted (Actual): July 30, 2024

Study Record Updates

• Last Update Posted (Actual): April 11, 2025
• Last Update Submitted That Met QC Criteria: April 10, 2025
• Last Verified: April 1, 2025

More Information

Terms related to this study

• Keywords: Stiff-Person Syndrome; Efgartigimod
• Additional Relevant MeSH Terms: Central Nervous System Diseases; Nervous System Diseases; Pathologic Processes; Neuromuscular Diseases; Autoimmune Diseases; Immune System Diseases; Disease; Autoimmune Diseases of the Nervous System; Spinal Cord Diseases; Syndrome; Stiff-Person Syndrome
• Other Study ID Numbers: STUDY006922

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: IPD will be shared between designated study sites during the trial. After the end of the trial data may be shared but this has yet to be determined.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No