Venom immunotherapy: clinical efficacy, safety and contraindications

Abstract

Venom-specific immunotherapy (VIT) is considered for the treatment of patients with IgE-mediated systemic allergic reactions (SARs) after developing a Hymenoptera venom allergy. Tolerance is achieved in a majority of patients after only a few days or even hours of rush immunotherapy. After VIT discontinuation, the allergy returns in up to 15% of patients. During VIT, the majority of patients have local reactions at the site of venom injections. SARs to VIT are much more frequent in honeybee-treated patients than in wasp-treated patients. Increased baseline serum tryptase and increased allergen-specific sensitivity of basophils are other factors that might be associated with systemic reactions (SRs) during VIT. Severe SRs occur mainly during the build-up phase but can also occur in the maintenance phase of the VIT, even in patients with a well-tolerated dose-increase phase. Pre-treatment with humanized anti-IgE antibodies (omalizumab) is effective in patients with repeated SARs; however, this use of omalizumab is off-label. In highly exposed patients with a history of very severe reactions, there are virtually no absolute contraindications for VIT.

Keywords:

• anaphylaxis
• basophil allergen sensitivity
• contraindications
• Hymenoptera venom allergy
• immunotherapy
• side effects
• tryptase

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

Key issues

• Venom immunotherapy (VIT) is effective for the prevention of serious allergic reactions to Hymenoptera stings. Tolerance is achieved in majority of patients after only a few days or even hours of immunotherapy.

• Patients receiving VIT showed a statistically significant improvement in their health-related quality of life scores compared with those given an epinephrine autoinjector.

• Treatment failure is observed more often in patients receiving honeybee VIT than in those receiving wasp VIT.

• Systemic reactions after immunotherapy injections are particularly common during the dose-increase phase of VIT and occur in up to 40% of honeybee-treated patients. The majority of reactions are mild. However, very severe reactions can occur in the maintenance phase of VIT, even in patients with a well-tolerated dose-increase phase.

• Mastocytosis is associated with a higher rate of severe side effects during VIT. Very high sensitivity of basophils to allergens is also an independent predictor of severe systemic reactions (SR) during the build-up phase of honeybee VIT.

• Contraindications for VIT are not as strict as those for immunotherapy for respiratory allergic diseases.

• The risk of relapse is as high as 15% and increases with an increased number of re-stings.