Orphan immunotherapies for allergic diseases.

OBJECTIVE

As confirmed by systematic reviews and meta-analyses, allergen immunotherapy is clinically effective in the treatment of allergic diseases. In particular, subcutaneous immunotherapy is a pivotal treatment in patients with severe reactions to Hymenoptera venom, whereas subcutaneous immunotherapy and sublingual immunotherapy are indicated in the treatment of allergic rhinitis and asthma by inhalant allergens. Other allergies related to animal dander (other than cat, which is the most studied), such as dog, molds, occupational allergens, and insects, have also been recognized. For these allergens, immunotherapy is poorly studied and often unavailable. Thus, use of the term orphan immunotherapies is appropriate.

DATA SOURCES: We used MEDLINE to search the medical literature for English-language articles.

STUDY SELECTION: Randomized, controlled, masked studies for orphan immunotherapies were selected. In the remaining cases, the available reports were described.

RESULTS

The literature on food desensitization is abundant, but for other orphan allergens, such as mosquito, Argas reflexus, dog, or occupational allergens, there are only a few studies, and most are small studies or case reports.

CONCLUSION

Orphan immunotherapy is associated with insufficient evidence of efficacy from controlled trials, an erroneous belief of the limited importance of some allergen sources, and the unlikelihood for producers to have a profit in making commercially available extracts (with an expensive process for registration) to be used in few patients. It should be taken into consideration that adequate preparations should be available also for orphan allergens.