The evidence
Perhaps the strongest evidence to date for VNS as a cytokine blocker in rheumatology comes from an open-label, 12-week study, also conducted by SetPoint, in 17 patients with active RA despite methotrexate treatment; some had failed biologics (Proc Natl Acad Sci U S A. 2016 Jul 19;113[29]:8284-9. doi: 10.1073/pnas.160563511).
The microregulator wasn’t ready yet, so investigators implanted a VNS system commercially available for epilepsy and reprogrammed it to deliver a 60-second pulse once a day to the left cervical vagus nerve, which was increased after a month to four 60-second stimulations a day in nonresponders.
The investigators “observed that TNF production in cultured peripheral blood obtained ... on day 42 was significantly reduced from” 21 days before the study was started (TNF 2,900 pg/mL on day –21, versus 1,776 pg/mL on day 42; P less than .05).
When VNS was shut off, TNF production increased; when it was turned back on, it dropped. Interleukin 6 also fell significantly among responders. Overall, DAS28-CRP scores fell about 1.5 points on the 10-point scale from baseline to week 12.
Two-year outcomes were recently reported (Ann Rheum Dis. 2018;77:981-2. Abstract SAT0240). All 17 patients elected to continue treatment after the initial 12 weeks. Biologics were added in nine subjects (53%), because of no or limited response to VNS. Investigators were free to change the VNS dosing regimen, which varied during the study extension up to eight 60-second bursts a day. The roughly 1.5-point improvement in DAS28-CRP was maintained at 2 years.
“These long-term data suggest that bioelectronic therapy may be used as an alternative to, or in combination with, biological[s],” concluded Dr. Chernoff and other study team members.