for people ages 18 years and up (full criteria)
at San Diego, California and other locations
study started
completion around
Principal Investigator
by Nathaniel Schuster, MD
Headshot of Nathaniel Schuster
Nathaniel Schuster



This is a Platform Protocol to perform Phase II clinical trials in The Early Phase Pain Investigation Clinical Network (EPPIC-Net), under The Helping to End Addiction Long-termSM Initiative, or NIH HEAL InitiativeSM, related to the treatment of Painful Diabetic Peripheral Neuropathy (PDPN) in a platform setting to test multiple assets under a single protocol.


This is a Platform Protocol that allows evaluation of more than one treatment in a single trial structure, to be run within EPPIC-Net. Instead of testing individual assets in a series of clinical trials, this Platform Protocol sets out the framework for testing multiple assets related to PDPN. This provides an efficient approach to evaluate multiple therapies under a single infrastructure in a timely fashion. The Platform Protocol also allows efficiencies by creating the possibility of sharing information across assets, such as data from control conditions.

This Platform Protocol is for a platform design to allow for the testing of multiple assets. Some platform trials allow direct comparisons of competing therapies for the same condition. However, for this EPPIC-Net platform trial, there will not be direct comparisons of assets to one another. Instead, assets will only be compared to a placebo. This is in service to the EPPIC-Net primary goal of accelerating the development of pain treatment because, based on feedback from asset-holders, the possibility of comparison of assets to one another or to an active drug would be a deterrent for asset-holders' participation in EPPIC-Net.


Painful Diabetic Neuropathy, Peripheral Nervous System Diseases, Diabetic Neuropathies, Pain, ISA specific, EN21-01 ISA


You can join if…

Open to people ages 18 years and up

  1. Able to provide informed consent. Legally Authorized Representatives (LARs) will not be permitted.
  2. 18 years of age and older
  3. Diagnosis of diabetes mellitus
  4. Meets the Toronto Criteria for probable clinical sensorimotor polyneuropathy, with PDPN symptoms present for at least six months. This is defined as a combination of symptoms and signs with any two or more of the following (must be present bilaterally in the distal lower extremities): neuropathic symptoms, decreased distal sensation, or unequivocally decreased (or absent) ankle reflexes. Specifically:
    1. The presence of any neuropathic symptoms on either the "Douleur Neuropathique en 4 Questions" (DN4) or the EPPIC-Net Neuropathy Exam will suffice to demonstrate "neuropathic symptoms." b. Decreased distal sensation is satisfied by any of the following: i. "Yes" is checked at least once under Question 3 of the DN4 which queries hypoesthesia to touch and pinprick.

    ii. At least one score of "reduced" or "absent" on the right AND at least one score of "reduced" or "absent" on the left in any of the following items from the EPPIC-Net

    Neuropathy Exam:

    • Pin sensation in segments 1 or 2 (i.e. the toes and feet)
    • Vibration at the great toe
    • Joint position at the great toe
    • Light touch/touch pressure at the great toe
    • Temperature at the great toe
    • Monofilament at the great toe c. Decreased or absent ankle reflexes is satisfied by a score of "reduced" or "absent" on the right AND left in the "Ankle reflex" item in the EPPIC-Net Neuropathy Exam.
  5. A score of at least 4 on the "Douleur Neuropathique en 4 Questions" (DN4).
  6. Pain reporting during a pre-defined 7-day screening period meets study criteria (to be established using a centrally-administered screening algorithm) which may account for mean pain intensity reported, variability in reported values, and adherence in reporting.
  7. Patient reported daily 11-point NRS (for average and worst pain over the last 24 hours) is completed on at least 5 out of the 7 days in the baseline period.
  8. Participants must be willing and able to comply with scheduled visits, the treatment schedule, laboratory testing, and other requirements of the study (e.g., completion of app-based daily reporting).
  9. Females may be included if they meet at least one of the following criteria (note that individual ISAs may specify more stringent measures to prevent pregnancy):
    1. Are not of childbearing potential, defined as one or more of the following: i. Post-menopausal for at least 1 year ii. Surgically sterile (bilateral tubal ligation, bilateral oophorectomy, or hysterectomy) iii. XY genotype iv. Turner syndrome v. Uterine agenesis. b. Are completely abstinent from sexual activity capable of resulting in pregnancy (as part of their preferred and usual lifestyle). This will include females whose sole sexual partner is a male who has undergone surgical sterilization or vasectomy.
    2. Women of childbearing potential will agree to practice an effective form of two types of birth control, which are defined as those, alone or in combination, that result in a low failure rate (i.e., less than 1% per year) when used consistently and correctly. This must be done before, throughout, and for 30 days after the last dose of study drug. Acceptable methods are: i. Hormonal methods such as the vaginal ring, or oral, implantable, injectable, or transdermal contraceptives for a minimum of 1 full cycle (based on the participant's usual menstrual cycle period) before study drug administration.

    ii. Intrauterine device. iii. Barrier method of contraception: condoms with or without a spermicidal agent, diaphragm or cervical cap with spermicide

    10. Specific requirements of male participants (regarding contraception) will be defined

    in the ISAs based on the potential toxicity profile of the asset.

You CAN'T join if...

3.1.1. Neuropathy Confound Exclusion Criteria

  1. Peripheral neuropathy caused by a condition other than diabetes (e.g. HIV, cancer/chemotherapy-induced, other medication-induced, alcohol-induced, hereditary, autoimmune neuropathies, uncontrolled or untreated hypothyroidism). Note that participants will not be tested for HIV, this will be established by patient report or review of the medical record.
  2. Other significant pain conditions involving the same area as the neuropathy (e.g. physical deformity of the feet, plantar fasciitis, lumbosacral radiculopathy with distal lower extremity pain, fibromyalgia involving the lower limbs, Morton's neuroma).
  3. Other pain conditions not involving the same area as the neuropathy which (in the opinion of the investigator) interfere with the participant's ability to rate the neuropathy pain.
  4. Any amputation of the lower limb which interferes with the participant's ability to rate the neuropathy pain. If there is any amputation please contact the MM.
  5. The presence of any current foot ulcer.
  6. Significant peripheral vascular disease defined as symptoms consistent with intermittent claudication.

    3.1.2. Medication/Treatment Exclusion Criteria

  7. Use of other investigational drugs within 3 months before screening and throughout the study.
  8. Known or suspected hypersensitivity to all of the assets (active component and excipients) currently being tested in the Platform Protocol.
  9. Undergone neurolytic or neurosurgical therapy or used an implanted neurostimulating device for neuropathic pain in the distal lower limbs within 3 months of screening.
  10. Use of the high dose capsaicin patch (8%) in the 6 months before screening and throughout the study (for the treatment of PDPN). Use of the capsaicin patch in a manner that is not expected to interfere with the measurement of PDPN severity is allowed.
  11. Participants who receive and are unwilling to discontinue episodic or periodic treatments for pain in the distal legs and/or feet (e.g., injections of local anesthetics) will be excluded. Non-pharmacological pain treatment (e.g. relaxation/hypnosis, physical or occupational therapy, any exercise-based therapy, any talk-based therapy, acupuncture, TENS) for the treatment of conditions other than PDPN is allowed. If the treatment is for PDPN it is allowed if it has been stable for at least 4 weeks prior to screening and is expected to remain stable throughout the study.
  12. Active use of opioids or marijuana for any reason at screening and unwilling or unable to discontinue use.

    3.1.3. Medical Exclusion Criteria

  13. Clinically significant ECG or laboratory abnormalities at the Screening Visit that would put the participant at undue risk or affect the ability of the participant to participate in the trial (in the opinion of the investigator). Screening ECG and lab results may be repeated without requiring a rescreen, as long as the participant is still within the screening window.
  14. Participants whose glycemic control has been unstable within 3 months before screening (e.g. ketoacidosis requiring hospitalization, any recent episode of hypoglycemia requiring assistance through medical intervention).
  15. Proliferative retinopathy or maculopathy requiring acute treatment.
  16. Requiring dialysis.
  17. Myocardial infarction or stroke in the past 6 months.
  18. Known diagnosis of moderate to severe hepatic impairment (equivalent to Child-Pugh class B or C) OR aspartate aminotransferase or alanine aminotransferase ≥ 3 times the upper limit of normal.
  19. A clinically significant illness or operative procedure within 4 weeks of screening.
  20. Clinically significant surgery planned during the study period. If a surgery is planned, please contact the MM.
  21. History of or currently active malignancy or other medical condition that would put the participant at undue risk or affect the ability of the participant to participate in the trial (in the opinion of the investigator).
  22. Pregnant or nursing (lactating) women. 3.1.4. Psychosocial and Substance Use Disorders

    Exclusion Criteria

  23. A clinically significant psychiatric disease that would put the participant at undue risk or affect the ability of the participant to participate in the trial (in the opinion of the investigator).
  24. Alcohol use disorder or other substance use disorders (other than nicotine or caffeine) in accordance with DSM-5 criteria within 12 months of screening.
  25. Positive urine drug tests defined as follows:
    1. Two positive urine drug tests for prescription opioids or marijuana, prior to the initiation of investigational product (IP); or
    2. One positive urine drug test for any illegal drugs (other than marijuana) prior to the initiation of IP.
  26. Vulnerable persons defined as either of the following:
    1. Individuals whose willingness to volunteer in a clinical study may be unduly influenced by the expectation, whether justified or not, of benefits associated with participation or of a retaliatory response from senior members of a hierarchy in case of refusal to participate.
    2. Individuals whose judgment has been impaired by their physical, mental, or socio-economical condition and those incapable of giving informed consent.


  • University of California, San Diego accepting new patients
    San Diego California 92037 United States
  • University of Utah School of Medicine accepting new patients
    Salt Lake City Utah 84132 United States

Lead Scientist at UCSD

  • Nathaniel Schuster, MD
    Associate Clinical Professor, Anesthesiology, Vc-health Sciences-schools. Authored (or co-authored) 40 research publications


accepting new patients
Start Date
Completion Date
James P. Rathmell, MD
Phase 2 research study
Study Type
Expecting 122 study participants
Last Updated