From: SKNews April 2013
San Antonio-A short course of treatment with an investigational synthetic cat-peptide-antigen desensitizing vaccine, or Cat-PAD, results in a substantial and persistent reduction in cat allergy symptom scores, according to 2-year findings from a randomized controlled study involving 202 adults patients.
Participants in the phase II trial were initially randomized to receive eight 3-nmol intradermal doses at 2-week intervals, four 6-nmol doses at 4-week intervals, or placebo. At 1-year follow-up, the improvement in Total Rhinoconjunctivitis Symptom Score (TRSS) was significantly greater in the patients who received four doses of Circassia's Cat-PAD (ToleroMune Cat) than in patients who received the placebo (-7.1 points vs. -2.99 points), investigators reported online in the journal of Allergy and Clinical Immunology (2013;131:AB147[doi: 10.1016/j.jaci.2012.12.1185]).
Data from a 2-year follow-up study were reported by Rod P. Hafner, Pd.D., and his colleagues in a poster at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Of 89 patients enrolled into the follow-up study, 50 returned at 2 years after the start of treatment, having received no additional treatment, for an environmental exposure chamber (EEC) challenge. The magnitude of difference from baseline in TRSS seen at 1 year in those who received four doses and those who received placebo was maintained at 2 years (-5.87 vs. -2.02 points) among those who initially received the four-dose regimen.
"Cat-PAD is the first in a new class of synthetic peptide immune-regulatory epitopes. The results from this study provide the first evidence that four doses of 6 nmol Cat-PAD over a 12-week period have a disease-modifying effect, with subjects showing sustained improvement at 2 years," the investigators wrote.
Study participants were aged 18-65 years with cat allergy who underwent a baseline EEC challenges at 18-22 weeks and at 100-104 weeks.
"Cat allergen was dispersed into the EEC to achieve a consistent mean level of approximately 50 ng Fel d1/m3, using a validated method," they explained, noting that TRSS was calculated at each EEC challenge based on self-scoring of four nasal symptoms (running nose, sneezing, blocked nose, itchy nose), and four ocular symptoms (itchy eyes, watery eyes, red eyes, sore eyes) on a scale of 0 to 3, every 30 minutes during the challenge.
Cat-PAD is a "potentially exciting new approach to cat allergy immunotherapy," the investigators said, noting that improvements in the TRSS seen in the initial phase II study and follow-up study represent a substantial improvement over numerous therapies investigated in the past, in symptom reduction.
In late 2012 the investigators began enrolling participants for a phase III study.
This study was funded by Circassia. Dr. Hafner is employed by Circassia.