The exact mechanism of action of specific immunotherapy is not fully understood. However, Grazax has been shown to induce a systemic competitive antibody response towards grass and an increase in specific IgG.
The efficacy of Grazax has been assessed in two studies. The first study was a double-blind, randomised trial conducted in 634 patients with confirmed IgE sensitivity and a two-year minimum history of grass pollen induced rhinoconjunctivitis1.
Patients received either Grazax or placebo once daily sublingually, 16 weeks prior to, and during the 2005 grass pollen season. Treatment continued for another two years and then patients were followed-up for a further two years. Results of the first treatment season have been presented.
Patients rated their rhinoconjunctivitis symptoms daily on a scale from 0 to 3 (no symptoms to severe symptoms). They self-medicated relief therapy in a stepwise fashion depending on the persistence and severity of their symptoms. Relief medication was scored according to predetermined criteria. Mean symptom and relief medication scores were calculated for the 2005 pollen season. A higher score indicates a higher level of symptoms or use of relief medication.
The mean scores for the Grazax group were significantly lower than the placebo group (30% reduction in symptom score and 38% reduction in relief medication score). The study also looked at the number of ‘well days’, defined as a day when the patient did not need any relief medication and had a symptom score no greater than 2 during the grass pollen season. The Grazax group had significantly less well days (27 days) than the placebo group (23 days).
The second study was a double-blind, randomised trial in 114 patients suffering from mild to moderate grass pollen induced asthma as well as rhinoconjunctivitis2. Patients received either Grazax or placebo once daily sublingually, 10–14 weeks prior to, and during the 2004 grass pollen season. Mean scores for rhinoconjunctivitis symptoms and use of relief medication were calculated as per the trial above.
The Grazax group showed a 37% reduction in the rhinoconjunctivitis symptom score, a 41% reduction in the relief medication score and a 54% increase in the number of well days. Patients also rated their asthma symptoms on a scale of 0 to 3 daily and had access to asthma relief medication. The differences in the asthma relief medication score and the asthma symptom score between the groups were negligible.
Overall, treatment with Grazax was well tolerated. There were reports of minor local adverse effects including ear or oral pruritus, throat irritation, sneezing and mouth oedema. The number of adverse effects linked to asthma was similar between the Grazax and the placebo groups and there was no indication of asthma aggravation.
1. Dahl R, Kapp A, Colombo G et al. Efficacy and safety of sublingual immunotherapy with grass allergen tablets for seasonal allergic rhinoconjunctivitis. J Allergy Clin Immunol, 2006: 118 (2); 434-40.
2. Dahl R, Stender A, Rak S. Specific immunotherapy with SQ standarized grass allergen tablets in asthmatics with rhinoconjunctivitis. Allergy, 2006: 61; 185-90.
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