Published Online: September 17, 2012
Cat allergy is common in the US with 17% of the population (equating to over 50 million people) testing positive in skin prick tests1 and 30% of allergic asthma attributable to cat allergen sensitization2. Treatment with cat-peptide antigen desensitization (Cat-PAD) consisting of T-cell epitopes is thought to down regulate allergic responses, without triggering the release of histamine and associated side effects. An earlier pilot study of this ToleroMune® treatment demonstrated its potential to improve patients’ symptoms following a short course. In a larger study published in The Journal of Allergy and Clinical Immunology (JACI), Patel et al investigated whether an increased dose of Cat-PAD given just four times over 12 weeks could further improve efficacy and continue symptom improvement without additional treatment a year after study drug administration started.
The double-blind, randomized study involved 202 patients with cat allergen-induced rhinoconjunctivitis. Prior to treatment, the participants recorded their nasal and eye symptoms while exposed to cat allergens in a controlled exposure chamber (which were combined to give a total rhinoconjunctivitis symptom score (TRSS)). Over the subsequent three months, patients received either four doses of Cat-PAD, eight lower doses, or placebo, following which they reassessed their symptoms in the exposure chamber. One year after the start of the initial study, 89 participants returned to the chamber to further reassess symptom scores.
The study found immediate and continuing improvements in patients’ symptoms following the four doses of Cat-PAD regimen, with a significant decrease in TRSS one year after the start of the study compared with both placebo and treatment with the more frequent but lower dose. Notably, the improvement appeared to increase further during the nine months after treatment ended. These findings were supported by improvements in both the component nasal and eye symptom scores. Cat-PAD was well tolerated with a safety profile similar to placebo. Most adverse events were mild and none were severe.
The authors conclude that four-dose short-course Cat-PAD can reduce rhinoconjunctivitis symptoms associated with cat allergy, with improvements continuing at least a year after the start of treatment. The decrease in TRSS achieved in the study represents a substantial improvement over a range of allergy therapies investigated previously using similar methodology, and reached two to three times the level of symptom reduction in some cases. Consequently, the study has identified the optimal dose and regimen for this potential new and exciting cat allergy treatment.
1. Arbes SJ, Gergen PJ, Elliott L, Zeldin DC. Prevalences of positive skin test responses to 10 common allergens in the US population: results from the third National Health and Nutrition Examination Survey. J Allergy Clin Immunol. 2005;116:377–383
2. Arbes SJ, Gergen PJ, Vaughn B, Zeldin DC. Asthma cases attributable to atopy: results from the Third National Health and Nutrition Examination Survey. J Allergy Clin Immunol. 2007;120:1139–1145
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.