A new clinical trial aims to determine the optimal timing for herpes zoster vaccination in rheumatoid arthritis patients starting JAK inhibitor therapy.
The STOP-HZ study, a randomized controlled trial enrolling 60 patients across 12 Japanese medical centers, will evaluate immune responses to the recombinant zoster vaccine (RZV) when administered concurrently with, or 8 weeks before, initiating tofacitinib treatment.
"JAK inhibitors are an important therapeutic option because of their oral administration route and efficacious action, possibly more effective than biological disease-modifying antirheumatic drugs," Satoshi Takanashi, MD, and colleagues wrote in an article published in BMJ Open. "However, the risk of developing herpes zoster is confirmed in almost all studies regarding JAK inhibitors."
The trial will divide participants into two groups. One group will receive tofacitinib (5 mg twice daily) simultaneously with their first RZV dose. In contrast, the second group will begin tofacitinib with their second RZV dose 8 weeks later. Both groups will receive RZV on day 1 and week 8.
The study's primary endpoint will measure VZV-specific IgG antibody titers at week 12 compared to baseline. Secondary endpoints include VZV-specific T-cell response, changes in rheumatoid arthritis disease activity, and adverse events.
Eligible participants must be 50 or older and have moderate to high disease activity despite being treated with antirheumatic therapy. Key exclusion criteria include prior herpes zoster vaccination or infection within the past year and recent use of specific immunosuppressive medications.
The investigators note that while herpes zoster can be treated with antivirals, prevention through vaccination is crucial given that "the incidence of postherpetic neuralgia is as high as 9.1%" and there exists "a risk of arthritis worsening with inflammation caused by the virus and suspension of immunosuppressive drugs."
The trial is expected to run from September 2023 through August 2025, potentially establishing evidence-based guidelines for optimal RZV administration timing in this patient population.
The research team has employed enzyme immunoassay and ELISPOT assays to measure both humoral and cellular immune responses. Safety monitoring includes tracking herpes zoster events, disease activity exacerbation, and adverse events throughout the 12-week study period.
The study is being funded by Pfizer under a research collaboration with Keio University, though the pharmaceutical company is not involved in patient recruitment, data collection, analysis, or interpretation.