Kate Johnson

March 07, 2012

March 7, 2012 (Orlando, Florida) — A keen interest in sublingual immunotherapy (SLIT) for allergy is evident here at the American Academy of Allergy, Asthma and Immunology (AAAAI) 2012 Annual Meeting, but the reported increased use of this therapy in nonresearch settings is "disturbing," according to one expert who spoke at the meeting.

"SLIT is used in many parts of the world. It is commonly used in Europe, but in the United States, there are no FDA [US Food and Drug Administration]-approved SLIT medications," explained Michael Blaiss, MD, speaking at a State-of-the Art session on SLIT in the United States.

Dr. Blaiss, who works in private practice in Memphis, Tennessee, and is a clinical professor of pediatrics and medicine at the University of Tennessee Health Sciences Center in Memphis, said it is disturbing to witness the use of SLIT in the "remote practice of allergy," meaning by nonallergists. "Even more disturbing to me is seeing more and more board-certified allergists doing SLIT off-label in the United States."

"I think it's still less than 10%, but we do know there's a growing use of SLIT by groups of otolaryngologists around the country, and by family physicians," he told Medscape Medical News. About 6% of allergists use SLIT, according to 2 surveys — one conducted in early 2007 by the American College of Allergy, Asthma, and Immunology and the other conducted in late 2009 by the Joint Council of Allergy, Asthma, and Immunology, he noted. "There are lots of people giving extracts that are approved for subcutaneous use...sublingually. I have concerns about that because we don't know the true efficacy or the true safety," he said.

In the United States, most SLIT is being used for allergic nasal disease; much less is being used for food allergy, confirmed Wesley Burks, MD, president-elect of AAAAI and chief of pediatric allergy and immunology at Duke University in Durham, North Carolina.

Dr. Burks is involved in several trials of SLIT — for milk and for peanut allergy — but he said it will be important to confirm its safety before people think about using SLIT in clinical practice.

"What we don't really understand is the safety profile. It was originally thought to be very benign. What we've seen in our studies, although the numbers are small, is that there are a few people who really will have systemic allergic reactions to it. If they take the drops and they cough or they aspirate in any way, you can have a serious systemic allergic reaction. It has happened in several instances," he warned.

In addition to questions about safety, there is the question about efficacy, said Dr. Blaiss.

"Patients need to be informed this is off-label; it's not approved by the FDA and we don't have clear data that this particular product has the levels of allergen that will work to control the condition. What the studies show is that if [the patient] isn't given enough of the allergen, [he/she] is not going to show clinical benefit."

He sees a long road ahead before SLIT is approved by the FDA.

"It's really still not clear from the FDA what is going to be required for the approval of SLIT in the United States. There's a much higher hurdle, compared with typical treatments and medication [in allergy], because what we're talking about here is not a medication — we're really talking about a vaccine."

For vaccines, the FDA is going to set a higher standard as far as efficacy and safety, Dr. Blaiss said.

With few good studies to date, many questions remain, such as the optimal dose and when it should be given, particularly with seasonal allergies, he said.

"Most of our patients are polysensitized; when we're treating subcutaneously, they are getting multiple different allergens. What happens when we do this with SLIT? One study showed that the efficacy was not the same when SLIT used multiple allergens."

If and when the FDA starts to move in the area of immunotherapy, approval will likely come first for oral (tablet) immunotherapy, Dr. Blaiss said.

Either way, the concept of immunotherapy is an exciting one because of its disease-modifying potential, he explained. "Can the use of SLIT in children with atopic rhinitis prevent or block the atopic march? Can it prevent the development of asthma and other allergies? The future for us and SLIT...is definitely exciting," he said.

Dr. Blaiss reports serving on the speaker's bureau for AstraZeneca, Merck, GSK, Sunovion, Nycomed, ISTA, Nestle, and Genentech; and serving as a consultant for Sanofi, Merck, Sunovion, Allergan, Alcon, Proctor & Gamble, Nycomed, ISTA, JDP Therapeutics, Pfizer, and PMD Healthcare. Dr. Burks reports being a minority stockholder in Allertein and Mast Cell; serving on an advisory board or expert panel for Dannon Company Probiotics and Nutricia; consulting for Exploramed Development, Intelliject, McNeil Nutritionals, Merck & Co, Novartis, Pfizer, Portola Pharmaceuticals, and Schering-Plough; receiving research support from the National Institutes of Health, the Food Allergy and Anaphylaxis Network (FAAN), the Food Allergy Initiative, the National Peanut Board, SHS, and the Wallace Research Foundation; providing legal consultation or expert witness testimony on the topic of food allergy; and being on the medical board of directors of FAAN.

American Academy of Allergy, Asthma and Immunology (AAAAI) 2012 Annual Meeting. Presented March 3, 2012.