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Keywords:

  • allergens;
  • anaphylaxis;
  • local reaction;
  • pharmacovigilance;
  • sublingual immunotherapy

We read with interest the publication by Eifan et al. (1) reporting about a 11-year-old girl treated with Staloral 300 IR mites SLIT, taken in the morning, and grass/cereal pollen, taken in the evening, who developed a severe oral and gastrointestinal reaction associated with high fever, causing her to attend the emergency department.

Following online publication, a medical team from Stallergènes met the authors in Istanbul. The meeting revealed the following information:

In the emergency department, body temperature was 39°C and a blood count was performed but the results were not available. The patient received dextrose infusion, intravenous (i.v.) H1-antihistamine and i.v. corticosteroids. Review of the clinical notes did not reveal any record of blood pressure/pulse, or clinical symptoms of asthma, urticaria or angioedema. Adrenaline was not administered. Approximately 4 h after admission to the emergency unit, and following significant improvement, the patient was allowed to leave the hospital with a prescription for H1-antihistamine. On the following day, treatment with Staloral pollen was resumed with recurrence of sublingual oedema and burning sensation. Pollen treatment was permanently discontinued.

Clearly, the reaction described as anaphylaxis was actually a severe local reaction with positive rechallenge. This reaction does not constitute a description of a serious anaphylactic reaction with the characteristics of anaphylactic shock as defined in the EAACI Immunotherapy Position Paper. This may reflect a difference in the way in which the word ‘anaphylaxis’ is used, as, by definition, a positive skin prick test could be construed as anaphylaxis, although this would lack the same significance as severe laryngeal oedema or life-threatening hypotension. This late statement is in line with a recent editorial by Warner (2).

This report followed two other recent publications of anaphylaxis in patients treated with SLIT (3, 4). Only one case satisfied the criteria for anaphylactic reaction: the patient received latex by a rush administration protocol (3), fortunately administered in a hospital. Rush protocol is associated with a higher risk than conventional protocols. Latex proteins are particularly potent allergens and in this particular context, can be compared with sublingual use of a full dose of bee venom. The second patient from the USA (4) reported a severe reaction with no clear evidence of anaphylaxis following SLIT with a mixture of six different allergens that was possibly not standardized and probably not used in compliance with the FDA-approved indication. These publications (1, 3, 4) raise two concerns. First, they raise the question of the rationale for administration of SLIT during the pollen season (1), but all clinical trials performed till date have been conducted with pre-seasonal administration without any dose reduction during the pollen season.

The second question concerns the use of mixtures of allergens for the treatment of polysensitized patients (1, 4). The majority of allergic patients are polysensitized even when they do not present multiple allergies. However, a recent large-scale clinical trial of SLIT (5) in 640 patients treated with a mixture of five grass pollens did not reveal any differences in terms of efficacy and safety between patients monosensitized to grass pollens and those also sensitized to other allergens, suggesting that polysensitization is not a contraindication. The first article reporting SLIT was published 20 years ago (6) and numerous studies have been published. Several hundred million daily doses have now been administered. No life-threatening side-effect has ever been described in the peer-reviewed literature (7). These publications emphasize the need for all physicians to comply with pharmacovigilance rules by reporting all serious adverse and unexpected reactions to allow the Marketing Authorisation Holder to complete their obligations.

We thank Dr I. Barlan and her colleagues of Marmara University Medical Hospital for their excellent welcome and collaboration. We are indebted to Professors Alain Didier, Philippe Devilliers and Dr Evelyne Pierron, members of an Independent Data Monitoring Committee, for critical review of this manuscript.

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