Sublingual Immunotherapy for Allergic Rhinitis and Conjunctivitis

Giovanni Passalacqua; Valentina Garelli; Francesca Sclifò; Giorgio Walter Canonica


Immunotherapy. 2013;5(3):257-264. 

In This Article

Unmet Needs

Despite the robust proof of the clinical efficacy and long-term effect of SLIT, some aspects need to be better elucidated:

  • The candidate patient who would receive the most benefit from SLIT. In this regard no predictive biomarker of efficacy has been identified so far, although some have been suggested.[61] The identification of a biomarker for subsequent clinical response to SLIT (as well as SCIT) would be of primary relevance, also considering the non-negligible cost of the treatment. So far, the treatment is given according to current guidelines and the assessment of its efficacy is only made on a clinical and a posteriori basis;

  • The adequate maintenance dose required. This has only been clearly established for grass tablets, whereas data are lacking for the other relevant allergens;

  • The best administration regimen (preseasonal, coseasonal, pre-/co-seasonal or continuous). According to the literature, for pollen allergies, the pre-/co-seasonal regimen seems to be the best choice, also from an economical viewpoint,[62–64] but direct head-to-head comparisons are nowadays scarce;

  • The standardization of extracts, which differ greatly in allergen content from one manufacturer to another.[65] Presently, each SLIT manufacturer standardizes their products according to arbitrary in-house reference, although many extracts report the average content of the major allergens in micrograms. A universal standardization of the extracts would allow better comparison of the various trials and products;

  • A universally accepted classification/grading system for side effects does not exist and this fact heavily limits the overall evaluation of the safety of SLIT in real life.

In addition, there are methodological problems with the published studies, mainly concerning description, sample size calculation and reporting.[66,67] The variability of regimens, doses, patients and outcomes, in fact, result in an unacceptable degree of heterogeneity, which strongly limits the conclusions provided by meta-analyses. Finally, a standardized methodology to conduct clinical trials is urgently needed.[6,68,69]