Skin patch for peanut allergy: Results significant, but ‘not positive’
Epicutaneous immunotherapy for peanut allergy delivered through a skin patch yields significantly greater response in terms of desensitization to peanut protein than placebo among children with peanut allergy, but misses a component of the primary endpoint to be considered “positive”, according to the PEPITES* study.
“[T]he results are not easy to interpret,” stated JAMA deputy editor Dr Jody Zylke, who was based in Chicago, Illinois, US, in an accompanying editorial.
“[Nonetheless,] because of the difficulty in managing peanut allergy, the potential severe consequences of a reaction, and the lack of available treatments, the editors considered the phase III study of the ‘peanut patch’ … [which provides] data on the effectiveness and adverse events compared with a placebo patch—to be important,” he wrote.
Primary endpoint met and missed
The phase III, multicentre, double-blind study randomized 356 children aged 4–11 years (median age 7 years, 61.2 percent male) in a 2:1 ratio to daily treatment with a peanut patch containing 250 g of peanut protein or a placebo path for 12 months.
The primary endpoint was the percentage difference in response rate between the two groups, with response being defined as a post-treatment eliciting dose** of ≥300 mg peanut protein on food challenge for participants with low baseline eliciting dose or ≥1,000 mg for those with high eliciting dose at baseline.
After 12 months of treatment, the peanut patch induced a response rate of 35.3 percent compared with 13.6 percent with placebo, corresponding to a 21.7 percent difference between groups which was statistically significant (95 percent confidence interval [CI], 12.4–29.8; p<0.001).
However, because the lower bound of the 95 percent CI did not reach the prespecified criterion of ≥15 percent to be considered a “clinically significant response”, the researchers said “the trial could not be considered positive”.
Nonetheless, the researchers argued that the 15 percent threshold was arbitrary and that “the clinical relevance of not meeting this lower bound of the CI … remains to be determined”, given that the 15 percent margin was recommended by the US FDA based on convention and there are no established treatments yet for food immunotherapy to enable effect size comparison.
“There is no precise determination or consensus regarding what threshold of sensitivity may confer clinically meaningful protection,” they contended.
Treatment-emergent adverse events occurred at a rate of 95.4 percent in the active group and 89 percent in the placebo group, with application site reactions such as itchiness, erythema, and swelling being the most common.
What does this mean?
“Clinicians will have to determine with patients whether a response of 35.3 percent with the peanut patch is worthwhile,” Zylke suggested. “Other factors that may influence decision making include adverse events.”
“In addition, the effectiveness, adverse events, adherence, and durability of epicutaneous therapy must be weighed against the similar metrics with alternative types of therapy, such as oral immunotherapy,” he advised.