Sublingual Immunotherapy - Is There a Role?
An Analysis of Long-Term Efficacy and Safety of Sublingual Immunotherapy: Criteria for Appropriate Patient Selection
G. Walter Canonica, MD FAAAAI
University of Genova
Prof. G. Walter Canonica, FAAAAI, is Professor and Chairman of Allergy and Respiratory Diseases at the Department of Internal Medicine, Genoa University, Italy
Walter Canonica is an internationally renowned expert on immunotherapy and allergic respiratory diseases, and has authored over 350 full papers in international journals. His main research interests encompass investigation of different subsets of T lymphocytes and their functional role in basic and clinical research (allergy, organ specific autoimmunity, CNS degenerative diseases and cancer); molecular events and interactions between immunocompetent cells, inflammatory cells, epithelial cells in allergic inflammation and airways remodeling; new antiallergic drugs and new strategies in the treatment of allergic disease; and clinical and immunopharmacological activities of biological response modifiers such as cytokines, monoclonal antibodies, allergen specific Immunotherapy, and corticosteroids.
From 2003-2005 Prof. Canonica served as the Secretary-General of the World Allergy Organization (WAO) and is 2005-2007 President-Elect of WAO. His numerous national and international roles include Vice President of INTERASMA – International Association of Asthmology, Secretary General of the Federation of the Italian Medial Societies-FISM, and Chairman of the EAACI-CME Continuing Medical Education Council. He is a past-President of the Italian Society of Respiratory Medicine.
Sublingual Immunotherapy-SLIT, is the youngest non-injective route of IT. The first experimental approaches were performed two decades ago. Safety of SLIT was reviewed in a number of official position papers, and was considered a good reason to promote further studies.
At present several DBPC trials are published and a general consensus on the clinical efficacy of SLIT in allergic rhinitis has been reached in Europe. To further support this position, Durham and co-workers published a metanalysis study demonstrating SLIT efficacy on both symptom and medication score reduction in allergic rhinitis patients (1). The same study found no evidence for such an effect in pediatric patients. With the availability of more studies for review, we recently performed a metanalysis in pediatric patients with the findings of Evidence Ia for both rhinitis and asthma symptom and medication scores reduction (2). Some of our studies demonstrated the clinical efficacy of SLIT and a concomitant effect on nasal inflammation. In a recently completed long term study (3 years) in birch allergic subjects we confirmed clinical efficacy, nasal inflammation decrease and pulmonary function improvement (3). The long-lasting persistence of the allergen extract at sublingual level has been demonstrated by our group using radiolabelled allergen. The absorption has been also monitored.
Comparative studies of Subcutaneous Immnotherapy (SCIT) vs SLIT are not sufficient to support a better effect of one of the two. The only DBPC DDummy study failed to demonstrate any statistical difference between the two treatments, and both were effective compared to placebo. Like SCIT-injective IT, SLIT has been found to prevent asthma onset and new sensitizations. It has been ascertained that SCIT has long lasting effect in several trials. SLIT was found, in a 10 year survey, to exert a 5 year significant effect after cessation of therapy. High dosages recently demonstrated a better effect compared to low ones (4).
The safely of SLIT is reported as one of the added values of this treatment and there has never been a report of a fatal or near fatal reaction. SLIT safety has been confirmed in clinical trials and in post marketing surveillance studies. SLIT was recently demonstrated to be as good in very young children (< 3 years of age) as it is reported to be in the published literature about adults. These last data strongly support the eligibility of young children to receive SLIT, in view of its efficacy, safety and preventive effect on disease progression (5).
1. Sublingual immunotherapy for allergic rhinitis: systematic review and meta-analysis. Wilson DR, Lima MT, Durham SR. Allergy. 2005 Jan; 60(1):4-12.
2. Efficacy of sublingual immunotherapy in the treatment of allergic rhinitis in children: A Meta-analysis of randomized controlled trials. Penagos M., Compalati E., Tarantini F., Baena Cagnani R., Huerta Lopez J., Passalacqua G., and Canonica G.W. Manuscript in preparation.
3. Clinical, functional, and immunologic effects of sublingual immunotherapy in birch pollinosis: a 3-year randomized controlled study. Marogna M, Spadolini I, Massolo A, Canonica GW, Passalacqua G. J Allergy Clin Immunol. 2005 Jun;115(6):1184-8.
4. Long-lasting effect of sublingual immunotherapy in children with asthma due to house dust mite: a 10-year prospective study. Di Rienzo V, Marcucci F, Puccinelli P, Parmiani S, Frati F, Sensi L, Canonica GW, Passalacqua G. Clin Exp Allergy. 2003 Feb; 33(2):206-10.
5. Post-marketing survey on the safety of sublingual immunotherapy in children below the age of 5 years. Di Rienzo V, Minelli M, Musarra A, Sambugaro R, Pecora S, Canonica WG, Passalacqua G. Clin Exp Allergy. 2005 May; 35(5):560-4.