METHODS: Patients >18 years old with IFA hypersensitivity were enrolled after completion of >3 months of IFA whole body extract (WBE) maintenance injections and assessment of efficacy via field sting or sting challenge. Once enrolled, the next 3 injections were given at 6, 8, and 12 week intervals with maintenance injections every 12 weeks thereafter. Laboratory evaluation, IFA skin test, and an IFA sting challenge were administered annually. Study approval was obtained from the IRB.
RESULTS: In this 5-year interim update, a total of 24 patients with a mean age of 41 years (range 18-62 years) completed a mean of 29 months (range 1-55 months) in the study. Median duration of monthly maintenance IFA WBE prior to study enrollment was 11 months (range 3-90 months). During the study period, subjects received a mean of 11 maintenance injections (range 0-19) at 12 week intervals. Over the course of 5 years, 14 participants cumulatively sustained 65 field stings with no systemic reactions. Seventy-three annual IFA skin tests were performed, after which one patient reported subjective symptoms (nausea and warmth) after testing. Zero patients developed systemic reactions to the annual sting challenge.
CONCLUSIONS: IFA WBE maintenance immunotherapy extended to a 12-week interval appears to be a safe and effective treatment option. This is an ongoing study.