NEW YORK (Reuters Health) - Omalizumab facilitates rapid oral desensitization in highly allergic patients with peanut allergy, researchers report.
Oral immunotherapy (OIT), the gradual exposure to increasing amounts of allergen, can lead to the majority of subjects tolerating doses of food sufficient to prevent reaction upon accidental exposure. Many patients, though, experience severe reactions during this desensitization therapy.
Based on recent evidence that omalizumab can decrease reactions during oral desensitization, Dr. Lynda C. Schneider from Boston Children's Hospital and colleagues in the PRROTECT study investigated the efficacy of omalizumab in conjunction with peanut OIT in a phase 2 trial of 37 highly allergic individuals.
Twenty-three of 27 participants on omalizumab completed the 250 mg desensitization, versus one of eight participants randomly assigned to placebo treatment, the researchers report in the Journal of Allergy and Clinical Immunology, online September 8.
The primary endpoint, the ability to tolerate a 2,000 mg dose of peanut protein six weeks after stopping treatment, was achieved in 23 of 29 participants originally randomized to omalizumab treatment (79% of the intent-to-treat population), and in 23 of 27 who actually received peanut immunotherapy (85%), compared with one of eight on placebo (p<0.01).
Six participants in the placebo group and two in the omalizumab group who were unable to tolerate 250 mg of peanut protein after eight weeks of desensitization were all able to tolerate 2,000 mg of peanut protein while receiving open-label omalizumab.
Two of the four individuals who failed to reach this endpoint both had symptoms suggestive of eosinophilic esophagitis (EoE).
Individuals who could tolerate 2,000 mg of peanut protein continued on that dose and underwent an open peanut challenge with a cumulative dose of 4,000 mg of peanut protein 12 weeks after discontinuation of study drug. Twenty-two of 29 omalizumab subjects and one of eight placebo subjects passed this challenge.
"Our study demonstrates that peanut OIT in combination with omalizumab allows for rapid, effective desensitization in the majority of peanut allergic patients, including those with high peanut-specific IgE levels," the researchers conclude.
"While omalizumab is expensive, requires repeated injections, and is associated with a risk of hypersensitivity reactions, we suggest that the benefits of omalizumab-enabled OIT may outweigh these downsides; additional studies will be required to further evaluate this proposition," the write.
Dr. Paul J. Turner from the University of Sydney, Australia, who recently reviewed oral immunotherapy for food allergy, told Reuters Health, "The use of adjuvants to aid OIT has huge potential. This study confirms the ability of omalizumab to significantly improve the time taken to achieve clinically-relevant desensitization."
"Of concern, 3 of 37 participants (8%) developed EoE: EoE continues to be a significant safety concern in OIT and this study confirms the need to screen for this throughout updosing," he said. "As the authors highlight, there is still a long way to go before we can be sure about which protocols are more safe and cost-effective in clinical practice."
Dr. Robert Wood from Johns Hopkins University School of Medicine in Baltimore, Maryland, who also studies food allergy immunotherapy, told Reuters Health by email that while this approach to peanut allergy desensitization seems feasible, "most patients can be successfully desensitized without the help of omalizumab. This will take longer and be associated with more reactions, but can easily be accomplished in most patients."
"There are some patients with peanut and other food allergies who might benefit from the coadministration of omalizumab with food OIT," he acknowledged. "The key is to find biomarkers to identify these patients."
Genentech provided funding for the study and employed one of the authors after study enrollment began.
Dr. Schneider was not available for comments.
J Allergy Clin Immunol 2016.
Omalizumab Aids Fast Oral Desensitization for Peanut Allergy. Medscape. Oct. 13, 2016.