The safety and efficacy of ALLERVAX CAT in cat allergic patients

Conventional immunotherapy for cat allergy is effective in reducing cat all ergy symptoms in many patients, but this type of immunotherapy can cause se vere reactions, including anaphylaxis, and often requires years of injectio ns for successful desensitization. To improve the efficacy of immunotherapy for cat allergic patients, synthetic cat allergen peptides (ALLERVAX CAT) were generated, based on analysis of the immunodominant T cell epitopes of cat allergen. These peptides lack the tertiary structure of native Fel dl a nd possess a significantly reduced capacity to bind to Fel dl-specific IgE. Using these peptides, we performed a multicenter, randomized, double-blind , placebo-controlled study of 133 cat allergic patients chronically exposed to cats or who had failed previous conventional cat immunotherapy. We eval uated the safety of ALLERVAX CAT treatment and determined whether ALLERVAX CAT treatment improved tolerance to cat allergen, as measured by symptom an alysis and pulmonary function testing. Three of the ALLERVAX CAT-treated pa tients required systemic epinephrine for adverse reactions, but the frequen cy of all adverse reactions in both groups was not statistically different from that of the placebo group. The majority Of adverse events were "late" events, most commonly associated with respiratory symptoms, and these event s declined with successive injections. ALLERVAX CAT given at a dose of 750 mu g/dose improved pulmonary function in patients with reduced baseline FEV 1, and global evaluation of the subjects' ability to tolerate cats improved significantly in the actively treated groups relative to placebo. Thus, al though therapy with ALLERVAX CAT is associated with some adverse events in patients with severe cat sensitivity, such therapy is an effective approach for the management of cat allergy, since it improves tolerance to cats and improves pulmonary function in cat allergic patients with reduced FEV1. (C ) 1999 Academic Press.