Sublingual immunotherapy: certainties, unmet needs and future directions

SUMMARY

The subcutaneous modality of immunotherapy injections (SCIT) remained for several decades the only available administration route. SCIT is effective and safe, when properly prescribed and administered, but a remote risk of severe side effects is present (1), and the occurrence of technical errors is still not negligible (2). The problem of the risk/benefit ratio prompted the search for safer administration routes (nasal, bronchial, oral)(3), including the sublingual one (SLIT) that was described in 1986 (4). In less than 20 years, due to the large amount of clinical data, SLIT achieved credibility, and was introduced in the official documents as a viable alternative to the classic injection route (5, 6) for both adults and children (Fig. 1). To date SLIT is commercialized and routinely used in many European countries. Despite the increasing optimism, it must be acknowledged that some aspects still need to be clarified, and that there is room for improvement. The unmet needs represent the basis for future research, whereas the clinical hypotheses would open the search for new indications and modalities.