KEYSTONE, COLO. – Sublingual immunotherapy is finally coming.
Allergy therapy using rapidly dissolving oral tablets instead of subcutaneous injections has been approved in Europe for years. With Food and Drug Administration approval of sublingual immunotherapy tablets for the treatment of grass and ragweed allergies considered highly likely later this spring, the expectation is that patients, their referring physicians, and allergists will have many questions about this game-changing therapeutic innovation.
Dr. Harold S. Nelson, who closely follows developments in the field, provided answers at a meeting on allergy and respiratory diseases sponsored by National Jewish Health.
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The Food and Drug Administration could approve the use of sublingual immunotherapy tablets for the treatment of grass and ragweed allergies in the next few months.
Among his key points:
• The effectiveness of sublingual immunotherapy (SLIT) for allergic rhinitis and allergic asthma is now thoroughly established. So are the optimal dosing regimens: SLIT tablets are dosed once daily at 30 times the optimal subcutaneous immunotherapy (SCIT) once-monthly maintenance dose. In other words, over the course of a month, a patient on SLIT will take a roughly 30 times greater dose of grass or ragweed allergen than will a patient on SCIT.
• SLIT for grass allergy will be approved for patients aged 5-65, while SLIT for ragweed will receive an indication for 18- to 65-year-olds.
• SLIT, like conventional subcutaneous immunotherapy, is disease-modifying therapy, which prevents new sensitization and progression to asthma.
• The optimal duration of SLIT is 3-4 years, which typically produces 7-8 years of persisting benefit before retreatment is needed.
• SCIT results in faster clinical improvement than does SLIT. And at least through the first 12-15 months, SCIT also appears to be significantly more effective.
• The use of SLIT in combination with mixes of other readily available pollen extracts is not supported by any evidence of efficacy.
• The big advantages SLIT offers over SCIT are convenience and safety. Although in U.S. clinical trials 1 in every 200-300 SLIT-treated patients experienced mild systemic reactions – typically with the first dose no fatal or near-fatal anaphylactic reactions have occurred. That’s why SLIT will be approved for at-home use after a first in-office observed dose. However, the FDA will mandate that SLIT prescriptions be accompanied by coprescription of an epinephrine autoinjector, according to Dr. Nelson of National Jewish Health in Denver and professor of medicine at the University of Colorado at Denver.
Once SLIT products win FDA approval, the therapy will get a CPT code and become, for the first time, a billable treatment – a most welcome development. But Dr. Nelson emphasized that SLIT’s approval will also create a new dilemma for physicians and their many patients with multiple allergies, say, to trees, dogs, and molds in addition to grasses or ragweed.
"Something everybody’s going to have to decide is where to position this treatment," Dr. Nelson said. "Most of the companies have no plans to take SLIT beyond the standardized extracts, which means grass, ragweed, house dust mite, and cat. You’re probably never going to have SLIT for cottonwood or juniper. And it seems unlikely that anyone is going to put a patient on tablets and injections at the same time. So it’s a decision that will have to be made for every patient: whether the ability to treat grass and ragweed, and later, house dust mite and cat, is sufficient for that patient. Because if it’s not, then probably the patient is still a candidate for SCIT."
The strategy of the companies developing SLIT is not that oral therapy is supposed to be a replacement for SCIT, but rather that it provides an immunotherapy option for patients who currently don’t receive it because they balk at the inconvenience of monthly in-office injections, he continued.
"The idea is that if these people are told, ‘You can just take a tablet at home,’ they’ll opt to get at least their allergies to grass and ragweed treated," Dr. Nelson explained.
Dr. Harold Nelson
Compliance and treatment persistence are going to be issues with SLIT, as documented in a Dutch retrospective study of 3,690 patients placed on SLIT and 2,796 who received SCIT. Only 23% of patients on SCIT stayed on treatment for the recommended 3 years. While that’s hardly a stellar adherence rate, it was actually more than three times better than with SLIT, where the rate was just 7%. The median duration of adherence with SCIT was 1.7 years, compared with 0.6 years for SLIT. The main reason patients stopped SCIT was the inconvenience, while the No. 1 reason people gave up on SLIT was ineffectiveness (J. Allergy Clin. Immunol. 2013;132:353-60).