State of the Art: Development of a Sublingual Allergy Immunotherapy Tablet for Allergic Rhinitis in Japan.

Allergic rhinitis (AR) caused by house dust mite (HDM) and Japanese cedar pollen (JCP) represents a significant, expanding health problem in Japan. Allergic symptoms often have a severe impact on the QOL such as sleep disturbance and reduced school and work performance. In addition to the classical symptoms, AR is known to be a risk factor for the development of allergic asthma, a potentially life-threatening condition. Allergy immunotherapy (AIT) is a well-documented, safe, effective treatment option for respiratory allergic disease. It has been demonstrated that AIT can provide relief from clinical symptoms and that AIT has the potential to provide long-term post-treatment effect. Although the mechanism of AIT is not fully understood, it can actively modulate protective allergen-reactive pathways of the immune system and alter the natural course of disease. Unlike pharmacotherapy, AIT addresses the basic immunological mechanisms that are responsible for the development and persistence of allergic conditions. Currently two main routes of AIT administration are commonly available, subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT). Both SCIT and SLIT are clinically effective, and SLIT is particularly well tolerated, with a lower risk of systemic allergic reactions compared with SCIT. To date, SLIT tablets have been developed for a range of different allergies including HDM and JCP and are the best-documented AIT treatment form. Here we introduce the current status of development of a SLIT tablet in Japan for AR, examine the clinical aspects and mechanism of action of AIT, and discuss the future directions of SLIT.