A Phase 1/2 interventional study of ST-503 and Sham (No Treatment) in Chronic Neuropathic Pain, sponsored by Sangamo Therapeutics. Suspended at 11 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-03.
Sponsored by Sangamo Therapeutics · Phase 1/2, Interventional, and Treatment
Study is suspended while Sangamo seeks a new sponsor for the ST-503-101 study
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).
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.
50 studies on the registry are indexed under Small Fiber Neuropathy; 12 are open to participants now.
This study's planned enrollment of 27 is below the median of 31 across 31 interventional studies indexed under Small Fiber Neuropathy.
Browse Small Fiber Neuropathy studies →Sangamo Therapeutics is the lead sponsor of 28 studies on the registry; none are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 4 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria
Drug- and alcohol-related:
Procedure-related:
Infectious disease-related:
Hepatic disease- and hepatotoxic medication-related:
Cancer-related:
a. History of cancer, including B-cell cancers, within 5 years of Screening
i. Exceptions to this exclusion are fully excised non-melanoma skin cancers, non- prostate cancer, and fully treated ductal carcinoma in situ of the breast, provided subject has been stable for at least 6 months
b. Previous or allogeneic bone marrow transplant, peripheral stem cell transplant or solid organ transplantation
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Procedure: Sham (No Treatment)
Genetic: ST-503
Genomic Medicine
Sham Procedure
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.
Time frame: 12 weeks
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
Time frame: 12 weeks
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
Time frame: 12 weeks
Columbia Suicide Severity Rating Scale (CSSRS) Rating
With a ≥ 1-point decline in suicidal ideation in Columbia Suicide Severity Rating Scale (CSSRS) responses
Time frame: 12 weeks
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.
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
Daily Sleep Interference Score (DSIS)
DSIS is assessed on an 11-point NRS, which ranges from 0 (none) to 10 (severe).
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
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.
Time frame: 12 Weeks
Plan to share: No
No publications or documents are linked to this record.
Started Dec 2025 (actual). Primary completion is estimated for Jul 2027, 19 months after the start.
How these figures are worked out, and which studies are left out of them.
Study is suspended while Sangamo seeks a new sponsor for the ST-503-101 study
Study is suspended while Sangamo seeks a new sponsor for the ST-503-101 study
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is suspended, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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