A Pilot Randomized Clinical Trial of Transcutaneous Auricular Vagus Nerve Stimulation for the Treatment of Frequently Relapsing Nephrotic Syndrome in Children

Study Design A parallel, double blinded, randomized placebo controlled trial comparing daily taVNS use with sham therapy will be conducted in children 3 to17 years of age with FRNS. Thirty participants with FRNS (defined as having 2 or more relapses in 6 months within 6 months of diagnosis or 4 or more relapses in any 12 month period) will be randomized 1 to 1 to taVNS or sham therapy. Participants will be enrolled at two pediatric tertiary hospitals over a two year time period, with completion of the study by year three. All participants will perform daily taVNS therapy (active for taVNS arm or inactive for sham arm) for 5 minutes each day for a total of 26 weeks. Participants will monitor heart rate with each treatment and log home urine results. Participants will be monitored monthly with in person study visits at Weeks 8, 16 and 26 alternating with virtual remote video visits at Weeks 4, 12 and 20. Biosample specimens will be collected at baseline, 8 weeks, 16 weeks and 26 weeks. There will be a follow up period of an additional 26 weeks. All participants will be given the option to receive the active taVNS treatment at the end of the randomized period.

Intervention The device is the Roscoe Medical Transcutaneous Electrical Nerve Stimulation (TENS) 7000 unit, a FDA approved commercially available handheld electrical pulse generator. A custom-produced silicone-equivalent electrode ear clip manufactured at Feinstein will be placed at the cymba concha of the left ear with electrode gel to provide stimulation (or sham) to the auricular branch of the vagus nerve. taVNS will be performed on the left side because there is less of a risk of cardiac side effects. Maximum power density limit calculations were performed based on data from the FDA as a function of pulse width, current amplitude, electrode size, and effective impedance, suggesting an electrode size of greater than 58 mm2 must be used. The custom-made electrodes for this study are larger than this limit, thus ensuring safety. The device will be set to a frequency of 30 Hz and pulse width of 300 μs based on previous literature. All participants in both trials will perform the intervention therapy for 5 minutes each day. The timing and duration of treatment are based upon the known half-life of the biological cytokine response, previous literature demonstrating efficacy of daily 5 minute treatments and our prior work. The study period will be 26 weeks. This time period was chosen based on the definition of FRNS using a 6-month period, prior clinical trials and ethical concerns for enrolling placebo controls for a longer period of time. All participants will be told that they may or may not feel stimulation from the device. Participants will be asked not to mention any aspects of the stimulation procedures to study investigators/physicians (except to the trainer) to maintain blinding. The device has a Patient Compliance Meter that can record the number of times it was used. This will be used to monitor compliance.

taVNS Group: The intensity setting for pulse amplitude will be adjusted to the participant's tolerance (if a sensation is felt) to a maximum level of 2.5. In patients who are under the age at which they can verbalize perceptual threshold and tolerability (<5 years), the investigators will initiate intensity at the lowest setting and incrementally increase the value until the level at which perceptual threshold, defined by changes in facial expression, patient becomes fidgety, or displays behaviors which denote sensation is being perceived. Then, the intensity level will be decreased till the perceptual indicators are no longer present, and the resultant level will be used for the treatment. A maximum power density of 150 milliwatts (mW)/cm2 will be utilized for patients under the age of 5 years, a level that is substantially below the 250 mW/cm2 maximum level defined by the FDA to prevent injury. Participants and guardians will be instructed to adjust intensity to highest level of tolerance each time the device is used and level will be logged.

Sham group: The sham device will be altered internally so that electrical stimulation is not delivered, but the device will appear to function (Feinstein Bioengineering). Externally, the sham device will look identical to the taVNS device. The participant will be told to increase the intensity until tolerated if a sensation is felt, but will be asked to stop at a maximum level of 3. This inactive sham method was chosen because previous studies have shown that stimulation with placement of the ear clip on other parts of the ear such as the earlobe, although not innervated by the vagus nerve, results in some vagus nerve activity. Inactive sham methodology has been used in previous studies.

Study Phases The study will consist of three parts. Part 1 - Screening Period- up to 8 weeks. Informed consent/assent will be obtained at screening prior to the conduct of any study-related procedures. Participants will be screened to confirm inclusion/exclusion criteria are met. Participants must be off steroid treatment for 14 days prior to Day 1 and the participant must be in remission (negative urine protein creatinine (UPC) on first morning urine) on Day 1.