Allergen-specific immunotherapy is currently the only causal therapy for the treatment of immediate-type allergies such as allergic rhinitis. In contrast to symptomatic therapies, the goal is to achieve sustained immunological tolerance to the allergens. Sublingual specific immunotherapy (SLIT) is a less complex patient-friendly alternative to the subcutaneous form of application (SCIT).
Diseases caused by immediate-type allergies have a high prevalence in our latitudes. Up to 40% of the European population suffers from allergic rhinitis, which is triggered by airborne allergens such as tree or grass pollen [1]. Hay fever, together with allergic asthma and atopic dermatitis, is one of the atopic diseases that share a genetic predisposition to allergic reactions [2].
For whom is Sublingual Allergen Specific Immunotherapy suitable?
The clinical indication is proven IgE-mediated sensitization with associated clinical symptoms, taking into account preexisting conditions, medication, and contraindications [3]. IgE-mediated immediate-type allergies such as allergic rhinitis are based on complex gene-environment interactions and immunologically mediated hypersensitivity [3]. After initial sensitization against defined (glyco)proteins, an allergen-specific Th2 immune response develops and, upon renewed allergen contact, IgE-triggered release of inflammatory mediators (e.g. histamine) occurs, which trigger the allergic symptoms. Allergen-specific immunotherapy (AIT) is currently the only disease-modifying and curative treatment option. In Switzerland, AIT preparations are available for the treatment of allergies to tree and grass pollen.
Reduce allergy symptoms in the medium and long term
In allergen-specific immunotherapy, the administration of allergen extracts activates specific blocking antibodies, tolerance-inducing cells, and second messengers that prevent further amplification of the immune response triggered by allergens, block the specific immune response, and dampen the inflammatory response in tissues [4]. It is therefore a hyposensitization as a causal immunomodulating therapy with the aim of reducing allergy symptoms in the medium and long term. Specific sublingual immunotherapy is given by tablets or drops and should be continued for a period of 3 years [5]. Occasionally, itching or swelling may occur in the mouth area, which will subside in the course of treatment. As with subcutaneous immunotherapy, the respective preparation-specific indications and contraindications must be observed for the sublingual form of application.
Multiple proven evidence-based efficacy
Currently, subcutaneous (SCIT) and sublingual (SLIT) forms of immunotherapy are considered the standard of care [6]. SCIT is perceived by many patients as too burdensome. The sublingual form of application (SLIT) could be established as a possible alternative. The therapy usually lasts two to three years. According to the s2k guideline, the efficacy of SLIT in allergic rhinoconjunctivitis due to grass pollen allergy is very good in adults and children and well established in tree pollen allergy in adults [4]. A secondary analysis published in JAMA examined the efficacy and safety of SLIT in allergic rhinoconjunctivitis and allergic asthma [9]. Data analysis included 63 randomized controlled trials comparing SLIT with placebo, antiallergic pharmacotherapy, or other Specific Immunotherapy. In total, data from 5131 patients aged 4 to 74 years were analyzed. In allergic rhinitis and allergic conjunctivitis, improvement of more than 40% was achieved in 9 of 36 studies. A reduction of more than 40% in the need for antiallergic and antiasthmatic medications was reported in 16 of 41 studies. Regarding tolerability of therapy, local reactions were common, but no serious adverse events occurred, especially no anaphylactic reaction.
Preparations against tree and grass pollen available
In conclusion, sublingual immunotherapy for allergic asthma and allergic rhinitis has evidence-based efficacy with a favorable side effect profile and is associated with less effort than subcutaneous immunotherapy (SCIT). In Switzerland, preparations for sublingual immunotherapy are available against both grass and tree pollen. Grazax® and Oralair® [10] are approved for the treatment of grass pollen-related rhinitis and conjunctivitis in adults and children 5 years and older. For adults with seasonal allergic rhinitis, conjunctivitis and rhinoconjunctivitis caused by birch pollen, Staloral® is available. In addition, since 2020, the preparation Itulazax®, which is simultaneously active against several early-flowering plants (birch homologous group), has been approved for patients aged 12 years and older [10].
Literature:
- CK Care, www.ck-care.ch/news/2020 (last accessed Mar. 10, 2021).
- Allergy Information Service, www.allergieinformationsdienst.de/allergische-rhinitis.html, (last accessed Mar. 10, 2021).
- Mahler V: Immunotherapies of allergies: Current status. Health protection. 2020; 63(11): 1341-1356.
- Pfaar O, et al: Guideline on (allergen-) specific immunotherapy for IgE-mediated allergic diseases. S2k guideline 2014, www.awmf.org, (last accessed 10.03.2021).
- Medix: Factsheet Hay Fever 2018, www.medix.ch, (last accessed 03/10/2021).
- Klimek L, et al: New forms of application immunotherapy for allergic rhinitis. Der niedergelassene Arzt 2017, www.der-niedergelassene-arzt.de (last accessed 10.03.2021).
- Durham SR, et al: The New England journal of medicine 1999; 341(7): 468-475.
- Pajno GB, et al: Clin Exp Allergy 2001; 31(9): 1392-1397.
- Lin SY, et al: Sublingual immunotherapy for the treatment of allergic rhinoconjunctivitis and asthma: a systematic review. JAMA 2013; 309(12): 1278-1288.
- Swissmedic: Medicinal product information, www.swissmedicinfo.ch, (last accessed 10.03.2021
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