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Chronic Neuropathic PainPhase 1/2NCT06980948

Safety and Tolerability Study of ST-503 for Refractory Pain Due to Peripheral Neuropathy (Small Fiber Predominant, SFN)

A Phase 1/2 study testing ST-503 in people with Chronic Neuropathic Pain, run by Sangamo Therapeutics at 11 sites in United States.

Suspended

Paused. Enrolment is on hold for now and may resume.

Official record
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Trial summary

This research is being done to study a possible treatment for refractory pain due to small fiber neuropathy (SFN). ST-503 is intended to deliver a modified copy of the gene which will ideally repress Nav1.7 tissue-related pain signals reaching the brain, which should reduce the refractory pain due to small fiber… Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Chronic Neuropathic Pain
What is being tested?
ST-503
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
27 participants
Where
11 sitesUnited States
Study dates
4 Dec 2025to Jul 2028
Phase
Phase 1/2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Diagnostic characterization of Small Fiber Neuropathy (SFN) according to the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities and Networks (ACTTION) criteria.
  • Medical record documentation that pain is refractory to 2 of 3 categories of first line medical therapy for at ≥ 6 months prior to screening.
  • Serum sample negative for pre-existing anti-AAV9 antibodies determined by assay detection limit

Who cannot join

  • Drug- and alcohol-related:
  • Persons using opioid analgesics for under 3 months or persons who are not on a stable dose of opioids; if on a stable dose, the dose may decrease over the course of the study but should not be increased.
  • History of known alcohol abuse, opioid analgesic abuse, or illicit drug abuse within 2 years of Screening.
  • Positive urine test for drugs of abuse (including opiates, benzodiazepines, amphetamines, cocaine, barbiturates, and phencyclidine) without prescription and investigator approval, at Screening and Day -1.
  • Use of cannabinoids is not permitted.
  • Persons with Fabry's disease, with erythromelalgia, with peripheral neuropathies due to alcohol or drug toxicity, or with diagnosed channelopathies
Show all 22Show fewer
  • Procedure-related:
  • Contraindications to LP, general anesthesia or sedation
  • Any medical disorders that, in the opinion of the Investigator, could interfere with LP including but not limited to evidence for a pressure gradient between supratentorial and infratentorial compartments, Arnold-Chiari malformation, bleeding diathesis, clinically significant coagulopathy, thrombocytopenia, increased intracranial pressure, or spine disease or past surgical procedures involving the spine
  • Infectious disease-related:
  • Active viral infection or bacterial
  • A severe infection (e.g., pneumonia, septicemia, central nervous system infections [e.g., meningitis, encephalitis]) within 12 weeks prior to Screening
  • Hepatic disease- and hepatotoxic medication-related:
  • Presence of clinically relevant liver disease
  • Hepatic dysfunction as indicated by one or more of the following: i. Albumin ≤ 3.5 g/dL ii. Total bilirubin > 1.5 x ULN and direct bilirubin ≥0.5 mg/dL iii. Alkaline phosphatase (ALP) > 2 x ULN iv. Alanine transaminase (ALT) or aspartate transaminase (AST) > 1.5 x ULN
  • Hepatotoxic medications should be avoided during the study period including acetaminophen exceeding 4 gm/day unless essential to patient's treatment, approved by investigator, and hepatic dysfunction is not identified
  • Hepatotoxic supplement use during the study period
  • Cancer-related:
  • History of cancer, including B-cell cancers, within 5 years of Screening
  • Exceptions to this exclusion are fully excised non-melanoma skin cancers, non-metastatic prostate cancer, and fully treated ductal carcinoma in situ of the breast, provided subject has been stable for at least 6 months
  • Previous autologous or allogeneic bone marrow transplant, peripheral stem cell transplant or solid organ transplantation
  • Previously received gene or cellular therapy

Trial locations and contacts

11 sites in 1 country.

11 sites in 1 country

United States11 sites

  • Johns Hopkins University

    Baltimore, Maryland, 21218

  • Massachusetts General Hospital

    Boston, Massachusetts, 02114

  • University of North Carolina Medical Center

    Chapel Hill, North Carolina, 27514

  • The University of California, San Diego

    La Jolla, California, 92093

  • Dartmouth Hitchcock Medical Center

    Lebanon, New Hampshire, 03766

  • University of Arkansas for Medical Sciences

    Little Rock, Arkansas, 72205

  • Vanderbilt University

    Nashville, Tennessee, 37235

  • Columbia University Irving Medical Center (CUIMC) and New York-Presbyterian Hospital (NYPH)

    New York, New York, 10027

  • Virginia Commonwealth University

    Richmond, Virginia, 23284

  • University of Utah

    Salt Lake City, Utah, 84112

  • HonorHealth

    Scottsdale, Arizona, 85260

Other trials in United States

About this study

Official title: A Multicenter Phase 1 / 2 Double-blind, Randomized, Sham-controlled Dose Escalation Study to Determine Safety and Tolerability of Single Dose Intrathecal ST-503 Gene Therapy for Refractory Pain Due to Peripheral Neuropathy (Small Fiber Predominant, SFN)

This research is being done to study a possible treatment for refractory pain due to small fiber neuropathy (SFN).

ST-503 is intended to deliver a modified copy of the gene which will ideally repress Nav1.7 tissue-related pain signals reaching the brain, which should reduce the refractory pain due to small fiber neuropathy (SFN).

Read the detailed description

This research is being done to study a possible treatment for refractory pain due to small fiber neuropathy (SFN).

Small fiber neuropathy happens when something damages small nerve fibers in your skin, causing symptoms like painful tingling or burning sensations in your hands and feet. Pain originating in the nerves outside of the brain and spinal cord is defined by doctors as neuropathic pain. Scientists have discovered that certain proteins in our bodies called sodium channels are important for communicating pain signals in nerves, specifically, Nav1.7, Nav1.8 and Nav1.9. This first-in-human study will test the use of a type of experimental treatment called "gene therapy." The primary goal is to determine if it is safe and well tolerated. The second goal is to determine if it reduces the level of refractory pain due to SFN disease. The gene will be delivered into your cells using a special delivery tool called a vector.

Being tested
ST-503, Sham (No Treatment)
Keywords
Small Fiber Neuropathy
Medical subject headings
Small Fiber Neuropathy

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • ST-503Genetic

    Genomic Medicine

  • Sham (No Treatment)Procedure or surgery

    Sham Procedure

Study groups in NCT06980948
Study groupRoleWhat they receive
Sham Controlled StudySham comparatorNot described
Receives: Procedure: Sham (No Treatment)
Investigational AgentExperimentalNot described
Receives: Genetic: ST-503

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence and severity of treatment emergent adverse events (TEAEs)

    To assess safety and tolerability of ST-503 over a 12-week post-dosing observation period.

    Measured: 12 weeks

Secondary outcomes (11)

  1. Percentage of subjects with pain intensity reduction from baseline at Week 12

    • 30% in the weekly average of daily pain intensity measurements performed using the PI-NRS
    • 50% in the weekly average of daily pain intensity measurements performed using the PI-NRS
    • Dose of rescue medication use
    • Frequency of rescue medication use

    Measured: 12 weeks

  2. Percentage of subjects at Week 12

    • Categorized as improved on the patient global impression of change (PGIC) assessment
    • With a ≥ 1-point improvement in suicidal ideation in Columbia Suicide Severity Rating Scale (C-SSRS) responses

    Measured: 12 weeks

  3. Columbia Suicide Severity Rating Scale (CSSRS) Rating

    With a ≥ 1-point decline in suicidal ideation in Columbia Suicide Severity Rating Scale (CSSRS) responses

    Measured: 12 weeks

  4. Overall Pain Intensity Numerical Rating Scale (PI-NRS) score

    Participants will rate their pain intensity using an 11-point Numerical Rating Scale (0=no pain and 10=worst possible pain) and record their score in an electronic diary.

    Measured: 12 Weeks

  5. Short Form McGill Pain Questionnaire-2 (SF-MQ-2)

    This pain scale was developed to evaluate chronic neuropathic and non-neuropathic pain in adults. It consists of 22 descriptors of pain in 4 parts (continuous, intermittent, neuropathic, and affective pain types) to be rated from 0-10 with 0 indicating no pain and 10 the worst pain ever during the past week.

    Measured: 12 Weeks

  6. Daily Sleep Interference Score (DSIS)

    DSIS is assessed on an 11-point NRS, which ranges from 0 (none) to 10 (severe).

    Measured: 12 Weeks

  7. Hospital Anxiety and Depression Scale (HADS)

    HADS is a screening tool for anxiety and depression in non-psychiatric clinical populations consisting of 14 items (seven each for anxiety and depression). Higher scores correlate with worse symptoms.

    Measured: 12 Weeks

  8. Rasch-Transformed 13-item SFN Symptoms Inventory Questionnaire

    The 13-item SFN-SIQ evaluates changes in physiological functions such as sweating patterns and incontinence using a four-point Likert scale (0 = never present, 1 = sometimes, 2 = often, and 3 = always present) to get a sum of the grading scores attributed to each of the 13 items with a 0 to 39 range. Higher scores correlate with worse symptoms.

    Measured: 12 Weeks

  9. SFN-specific Rasch-built Overall Disability Scale (SFN-RODS)

    The 32-item SFN-RODS is a disease-specific interval measure suitable to detect activity limitations and participation restrictions in patients with SFN. The scale ranges from 0 to 64 with higher numbers indicating worse disability.

    Measured: 12 Weeks

  10. 36-Item Short Form Health Survey (SF-36) domains and summary scores

    This measures quality of life measures such as physical functioning, emotional well-being, energy levels, and social functioning. The range is from 0-100 with higher scores being associated with a better perceived quality of life.

    Measured: 12 Weeks

  11. Pain Catastrophizing Questionnaire (PCS)

    PCS has 13 questions related to rumination, magnification and helplessness with values ranging 0 to 4 for a total possible score of 52. The higher the score the more pain catastrophizing is present.

    Measured: 12 Weeks

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted20 May 2025
  2. Study start4 Dec 2025
  3. Primary completionJul 2027 (estimated)
  4. Study completionJul 2028 (estimated)

Why it stopped: Study is suspended while Sangamo seeks a new sponsor for the ST-503-101 study

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Model description
double-blind, randomized, sham-controlled dose escalation study
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
27 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06980948
Sponsor's protocol ID
ST-503-101
Status last verified
Oct 2026
First submitted
30 Apr 2025
Last updated
3 Nov 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
Yes
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing ST-503 in people with Chronic Neuropathic Pain, run by Sangamo Therapeutics at 11 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 22 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: paused, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 11 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Results are not available in the source record.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Incidence and severity of treatment emergent adverse events (TEAEs) (time frame: 12 weeks). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06980948.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Nov 2026.

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