Vagus Nerve Stimulation Proves Effective in Refractory RA

WASHINGTON — An implantable vagus nerve stimulation (VNS) device effectively treats moderate to severe rheumatoid arthritis (RA) in patients who had previously failed at least one biologic or targeted synthetic disease-modifying antirheumatic drug (b/tsDMARD), according to results from a phase 3 trial.

Of the 242 patients in the RESET-RA study, all received the VNS device implant but were blinded as to whether the device was turned on. At 12 weeks, 35.2% of patients receiving daily stimulation achieved 20% improvement in American College of Rheumatology response criteria (ACR20) compared with 24.2% of those with an inactive device. The response was more pronounced among patients with exposure to only one prior b/tsDMARD. A greater proportion of patients in the overall treatment group also reached low disease activity or remission compared with those who did not receive stimulation. 

The research was presented as a late-breaking poster at the ACR 2024 Annual Meeting.

“This is a particularly tough-to-treat patient population, since the patients enrolled were considered refractory to biologic therapy,” said Elena Schiopu, MD, professor of medicine in the Division of Rheumatology and director of clinical trials at the Medical College of Georgia at Augusta University. More than one third of patients in the study had tried three or more b/tsDMARDs prior to the study. “I’m pretty excited about these results,” she added. Schiopu was a RESET-RA institutional principal investigator and enrolled two patients in the trial.

These positive results are a first for VNS treatment in rheumatic diseases. Previous studies demonstrating the potential therapeutic effect of this implant approach have largely been open-label, proof-of-concept, or pilot studies. Noninvasive, wearable stimulation devices have also shown promise in open-label studies; however, a sham-controlled trial published in 2023 showed that transcutaneous vagus nerve stimulation on the ear was no more effective than placebo. 

But How Does It Work?

The device, developed by SetPoint Medical in Valencia, California, is about the size of a multivitamin and implanted in an outpatient setting. During the 45-minute procedure, surgeons isolate the vagus nerve on the left side of the neck and place the nerve stimulator with a silicone positioning pod to hold it in place.

The device is programmed to deliver stimulation for 1 minute every day and needs charging for only 10 minutes once a week, which is done remotely with a necklace.

The device takes advantage of the vagus nerve’s anti-inflammatory properties, stimulating the nerve to help regulate an overactive immune system of someone with RA, explained David Chernoff, MD, Setpoint Medical’s chief medical officer. 

“We’re recapitulating what nature has developed over millions of years, which is the nexus between the brain and the immune system, which happens to be mediated by the vagus nerve,” he told Medscape Medical News. 

This novel VNS approach also does not have the same immunosuppressive safety concerns as drugs commonly used to treat RA, he said. 

“We’re able to adjust the amount of inflammation, but we don’t cause the host defense issues” that are present with some of these drugs, he continued.

SetPoint Medical’s pilot study of the device in 14 patients showed promising results. Five of 10 patients randomly assigned to active VNS over 12 weeks showed clinical improvements, measured by 28-joint Disease Activity Scorebased on C-reactive protein (DAS28-CRP) and the Clinical Disease Activity Index. In the remaining four patients who received sham stimulation — where the device was implanted but not activated — there were no clinical disease improvements.

RESET-RA Details

The most recent, much larger phase 3 study enrolled patients from 41 sites in the United States. Patients were on average 56 years old and had a body mass index of 30; 86% were women. A total of 39% had previously tried one b/tsDMARD, 22% had tried two, and 39% had tried three or more. Patients, on average, had 15 tender joints and 10 swollen joints. Patients discontinued their prior b/tsDMARD before the procedure and remained on conventional DMARDS during the trial, including methotrexate, hydroxychloroquine, and sulfasalazine.

The researchers randomly assigned patients 1:1 to active (treatment) or nonactive (control) stimulation. 

“The perception of stimulation varies from patient to patient, which itself is helpful in blinding as there is no expected perception of whether or how stimulation will be felt,” Chernoff explained. The 1-minute stimulation was scheduled in the early hours of the morning, when a patient typically would be asleep, he said.

Patients were excluded from the analysis if they were rescued by steroids or b/tsDMARDs through week 12. After week 12, the control group was switched to stimulation and efficacy was reassessed at week 24.

Higher ACR20 Response Rate, Lower Disease Activity

Beyond meeting the primary endpoint of ACR20 response, patients on the active stimulation group showed lower disease activity at week 12. Compared with 15.8% of patients in the control group, 27% of those in the treatment group achieved a DAS28-CRP ≤ 3.2. 

The active stimulation was particularly effective in patients who had experience with only one prior b/tsDMARD. In this subset of patients, 44.2% in the treatment group achieved ACR20 compared with 19.0% in the control group.

During this sham-controlled trial period, 13.1% of patients in the treatment group and 18.3% of patients in the control group reported an adverse event (AE) related to the procedure or device, most commonly vocal cord paresis or dysphonia. In the treatment group, 8.2% reported stimulation-related AEs, most commonly mild/moderate pain that was managed by adjusting the stimulation level. 

Serious adverse events (SAEs) were relatively rare, with four treatment-related SAEs across both study groups. No AEs led to study discontinuation through week 24.

The 12-week results mirror those of the initial Humira and Enbrel trials in the late 1990s and early 2000s, Schiopu said, although in those trials, the patients were naive to biologics, and some were naive to methotrexate. A more appropriate comparison, she said, would be biologic-experienced populations.

At week 24, the percentage of patients achieving ACR20 further increased to 51.5% in the treatment group and to 53.1% in the previous control group who were now crossed over to active stimulation. In this secondary period, patients could add any additional therapies like steroids or b/tsDMARDs. At 24 weeks, 81% of patients remained on stimulation without needing additional medication, beyond their continued background DMARDs. 

The results also show “a continuum of improvement over time,” Schiopu said, where response rates climbed through week 24. 

Schiopu is particularly excited about the potential to use this stimulation device in older patients, who have perhaps been on immunosuppressant drugs for decades. 

“Aside from being chronically immunosuppressed, their immune system is more tired [due to age],” she said. With VNS therapies like SetPoint’s, “we could offer [these patients] a lesser immunosuppressive alternative that is still immune-modular enough to manage their RA.”

Schiopu is a consultant for Johnson & Johnson and reported receiving research funding for serving as an institutional principal investigator for SetPoint, Galapagos, Johnson & Johnson, Boehringer Ingelheim, Lilly, argenx, EMD Serono, Priovant, Novartis, BMS, Zena Pharmaceuticals, and Horizon/Amgen.