Efficacy Study of Sublingual Immunotherapy to Treat Ragweed Allergies

Specific allergen immunotherapy as currently practiced in the USA and described in product labeling comprises the subcutaneous injection of incrementally increasing doses to a targeted maintenance dose ("build-up") followed by maintenance injections of allergenic extract/vaccine. Up to 30-40 injections may be required during the build-up phase over a 3-6 month period. When adequate maintenance doses are reached, this form of immunotherapy (SCIT) has been shown to be highly effective and safe.

Standard practices recommend that the injections be given under the supervision of trained physicians and that the patient remain in the physician's office at least 20 to 30 minutes after an injection. The administration of immunotherapy injections are not recommended at home because of the risk of inadequate recognition and treatment of systemic reactions. The inconvenience and expense of traveling for allergy injections and the discomfort of the repeated injections is a disincentive to this form of treatment particularly in pediatric patients. For example, dropout rates exceeding 50% over a multi-year course of injection treatment have been reported.

Alternative routes for immunotherapy have been explored, especially in Europe in an attempt to improve patient compliance and to minimize the risk of serious adverse reactions. For example, sublingual-oral immunotherapy (SLIT), which is the administration of the allergenic extract/vaccine under the tongue for 1-2 minutes followed by swallowing, has been proven to be efficacious and safe in several double-blind, placebo-controlled studies. A recent Cochrane Review concluded, "SLIT is a safe treatment, which significantly reduces symptoms and medication requirements in allergic rhinitis."

Efficacy studies support the use of SLIT for the treatment of rhinitis or rhinitis and asthma. However, dosage schedules are highly variable and optimal maintenance doses have not yet been established. Thus, dosing studies should be designed to investigate not only the safety profile but to determine optimal doses for maintenance therapy of patients built-up by injection IT and for build-up regimens of previously untreated patients.

Much of the United States medical community's hesitation to embrace sublingual immunotherapy as a viable treatment option for allergy patients has stemmed from limited information using U.S. licensed allergenic extracts for this treatment route. Additionally, the cost-effectiveness of one form of therapy over the other has not been clearly evaluated and the third-party payers have not accepted SLIT for insurance coverage.

Inclusion criteria

• Adult ragweed-sensitive Subjects with allergic rhinoconjunctivitis with or without asthma during ragweed pollen season.
• Subjects must be 18 to 50 years of age.
• Test Subjects will have a history of moderate to severe isolated or unseasonal allergic rhinoconjunctivitis with or without mild intermittent asthma symptoms attributable to ragweed pollen for a minimum of 2 years before study entry.
• Subjects with or with out a history of asthma will possess FEV1 and PEF greater than or equal to 80% predicted at the beginning of the study established by spirometry and defined by the Knudson predicted set.
• Sensitivity to the relevant allergen will be documented by a positive skin prick test result performed along with negative (saline) and positive (histamine) control skin tests. A positive test will be defined as the skin reaction having the longest wheal diameter of 5mm or greater or the longest erythema diameter of 10 mm or greater at 15-20 minutes after application.
• All female Subjects of child-bearing potential will be required to provide a urine sample for pregnancy testing that must be negative before being allowed to participate in the study.
• Subjects must be planning to remain in the study area during the trial (see exclusion criteria # 14).
• Subjects must be trained on the proper use of the EpiPen, and sign the EpiPenTraining Form before being allowed to enroll in the study.
• Subjects must be mentally and physically capable of self-administering oral drug.

Exclusion criteria

• Subjects having a history of anaphylaxis or history consistent with persistent asthma
• Subjects taking antihistamines or nasal steroids medications greater than twice a week in the months of January and/or February.
• Subjects with chronic sinusitis unstable angina, significant arrhythmia, uncontrolled hypertension, or other chronic or immunological diseases that in the opinion of the investigator might interfere with the evaluation of the test drug or pose additional risk to the Subject.
• Subjects having perennial or structurally related rhinitis or rhinitis medicamentosa (from excessive use of nasal decongestants) that will interfere with the evaluation of symptoms due to ragweed allergy.
• Subjects with an FEV1 or PEF less than 80% predicted (moderate persistent asthma) with or without controller medication.
• Subjects who have received an experimental drug in the 30 days prior to admission into this study or who plan to use an experimental drug during the study.
• Subjects who have received Anti-IgE medications (Xolair) or similar compounds in the last 12 months.
• Subjects who have received ragweed allergen immunotherapy in the last 3 years prior to admission into this study.
• Subjects who are current users of inhaled, oral, intramuscular, intravenous corticosteroids, tricyclic antidepressants, beta blockers, or MAO inhibitors.
• Subjects using beta-agonist more than twice a month unless being taken prior to exercise.
• Subjects using medications that could induce adverse gastrointestinal reactions during the study. Subjects using such medications must prove stable with no side effects for at least 3 months prior to enrollment.
• Subjects refusing to sign the EpiPen Training Form will be excluded from the study.
• Pregnant or breast feeding females.
• Subjects who plan to leave the study area for more than 2 consecutive weeks during the study.
• Subjects with a positive skin prick test to cat and/or dog, and own the pet(s) to which they are allergic.
• Subjects who sleep during the day due to working third shift.
• Subjects unable to achieve dose #2 or higher during preliminary dosing will be excluded.