Early Trial of Peanut Patch for Peanut Allergy Shows Promise
18 Nov 2017
Bottom Line: A skin patch that delivered a high dose of peanut protein reduced peanut sensitivity in children and adults with peanut allergy, findings that warrant a phase 3 trial.
Why The Research Is Interesting: Allergy immunotherapy exposes people to a controlled dose of the proteins that trigger allergies so they become less sensitive or no longer sensitive. Peanut immunotherapy with a pill isn’t especially effective and carries the risk of triggering allergy just as eating a peanut would. Skin patch immunotherapy may have potential for more safely and effectively treating peanut allergy.
Who: 221 peanut-allergic patients (age 6-55 years)
When: Phase 2b trial: July 31, 2012 – July 31, 2014. Extension: Patients completing the trial participated in a 2-year extension using the most effective peanut-patch dose to assess efficacy for up to 36 months; extension study completed September 29, 2016.
What (Study Measures): The percentage of treatment responders in each group vs placebo patch after 12 months. Patients were considered treatment responders if it took 1,000 mg or more of peanut protein and/or 10-times the pretreatment amount of peanuts to trigger an allergic reaction.
How (Study Design): This was a phase 2b clinical trial that randomly assigned participants to a peanut patch containing 50 µg, 100 µg or 250 µg of peanut protein or placebo for 12 months. Phase 2b trials confirm the efficacy of an intervention and determine the most effective dose and are typically followed by a phase 3 trial in a broader population. Randomized clinical trials (RCTs) allow for the strongest inferences to be made about the true effect of an intervention such as a medication or a procedure. However, not all RCT results can be replicated in real-world settings because patient characteristics or other variables may differ from those that were studied in the RCT.
Authors: Hugh A. Sampson, M.D., Icahn School of Medicine at Mount Sinai, New York, and coauthors
Results: There were more treatment responders among patients given the 250-µg peanut patch (n = 28; 50 percent) than among patients given the placebo patch (n = 14; 25 percent). There was no difference between the placebo and 100-µg patch. The percentage of patients with one or more treatment-emergent adverse events (largely local skin reactions) was similar across all groups in year 1.
Study Limitations: The primary end point (10-times increase in challenge threshold) may not have been sufficiently stringent for the lowest food challenge doses, which contributed to the higher-than-expected rate of placebo responders. The sample size of each treatment group was relatively small and therefore, the study was not powered to detect a dose-response gradient.
Study Conclusions: These findings support testing of the 250-µg peanut patch dose in a phase 3 trial involving patients with peanut allergy.