When to Consider Sublingual Immunotherapy vs. Subcutaneous Immunotherapy

Clinicians have several options when it comes to treating their allergic patients with subcutaneous (SCIT) or sublingual (SLIT) immunotherapy. Désirée E.S. Larenas-Linnemann, MD, discussed the pros and cons of both types of therapy and her clinical experiences with them at the American Academy of Allergy, Asthma and Immunology’s 2015 annual conference in Houston, TX.

Linnemann began her talk by noting that when SCIT was the only immunotherapy available to treat allergic patients, clinicians had only two options: give subcutaneous shots or not. With the advent of SLIT, this scenario has drasticallychanged.

She mentioned that both SCIT and SLIT are effective regimens. Regarding safety, she told the audience that only one case of fatal systemic immune reaction with SCIT was reported, in 2009. In addition, the more severe systemic reaction rarely occurs (1:1,000,000). So far, no fatalities have been reported with SLIT, and the occurrence of severe systemic reaction is extremely rare. Nonetheless, she said that data from phase 4 clinical studies with SLIT are minimal, and that the current clinical experience is based on short-term studies. The fabrication and prescription of SLIT by non-allergists is another issue that should be considered.

Linnemann also commented on two SLIT drugs approved by the FDA, Grastek and Oralis. Grastek is indicated for the treatment of grass pollen-induced allergic rhinitis with or without conjunctivitis confirmed by positive skin test or in vitro testing for pollen-specific antibodies for Timothy grass or cross-reactive grass pollens. This drug is approved for use in persons from 5 to 65 years old. She reinforced that the first dose should be administered under a doctor’s supervision. Treatment should be started 12 weeks before the beginning of pollen season. If sustained effectiveness is desired, the drug should be taken daily for three years. Contra-indications are severe unstable asthma, history of systemic allergic reaction or local reaction to immunotherapy, or hypersensitivity to any of the components of the drug.

Caution should be taken when treating patients that are unresponsive to epinephrine or who are taking beta-blockers. The indications and contra-indications for Oralair are very similar to Grastek, but the treatment is recommended for patients from 10 to 65 years old. Also, Oralair therapy should be started 4 months before the beginning of the pollen season and should be given only throughout the season.

Mixing of drugs was another issue considered by Linneman. In the US, many allergens can be mixed together for SCIT, whereas in Europe only mono or pauci-allergen mixes are used. With SLIT, both mono and pauci-allergen mixes can be used. She highlighted, however, that one study has shown that SLIT with two-allergen mix works, and that treatment with ten-allergen mix does not have any effect.

The importance of patients’ adherence to immunotherapy treatments was also examined. Reports indicate that adherence to both SCIT and SLIT is very low in several countries, ranging from 6% to 50%. In Germany, where SCIT was administered perennially, adherence reached 60%, evidencing that different schedules may interfere with patients’ adherence. To conclude, Linneman said that the easier the schedule, the more the patient will adhere to the treatment.