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Grass Pollen Allergy Drug Grastek Gets FDA Green Light
The FDA has approved Grastek (Timothy grass pollen allergen extract, Merck) for sublingual use.
Grastek is an allergen extract indicated as immunotherapy for the treatment of grass pollen-induced allergic rhinitis with or without conjunctivitis confirmed by a positive skin test or by in vitro testing for pollen-specific immunoglobulin E (IgE) antibodies for Timothy grass or cross-reactive grass pollens.
The product is approved for use in persons 5 through 65 years of age. It is not indicated for the immediate relief of allergic symptoms.
The prescribing information for Grastek includes a boxed warning regarding severe allergic reactions. Grastek is contraindicated in patients with severe, unstable, or uncontrolled asthma; a history of any severe systemic allergic reaction; a history of any severe local reaction after taking any sublingual allergen immunotherapy; a history of eosinophilic esophagitis; or hypersensitivity to any of the inactive ingredients contained in the product.
Symptoms of grass pollen-induced allergic rhinitis with or without conjunctivitis may include sneezing, runny or itchy nose, stuffy or congested nose, or itchy and watery eyes, and typically intensify during the grass pollen season.
The recommended dose of Grastek is one tablet daily to be placed under the tongue, where it will dissolve.
The first dose of Grastek should be administered in a health care setting under the supervision of a physician with experience in the diagnosis and treatment of allergic diseases. The physician should observe the patient for at least 30 minutes after he or she receives the first dose of Grastek to monitor for signs or symptoms of a severe systemic or local allergic reaction. If the patient tolerates the first dose, he or she may take subsequent doses at home. The physician should prescribe auto-injectable epinephrine, and should instruct and train the patient on its appropriate use. Children must take Grastek under adult supervision.
Grastek is initiated at least 12 weeks before the expected onset of each grass pollen season, and treatment is continued throughout the season. The safety and efficacy of in-season initiation have not been established.
The efficacy of Grastek was supported by data from three pivotal studies.
The first study compared Grastek and placebo in 1,501 patients 5 through 65 years of age, of whom approximately 25% had mild, intermittent asthma and 85% were sensitized to other allergens in addition to grass. Patients treated with Grastek showed a significant reduction in nasal and ocular symptoms, and reduced use of symptom-relieving allergy medication, as measured by a decrease in the total combined score (TCS) for the entire grass pollen season, compared with placebo. The difference for Grastek (n = 629) compared with placebo (n = 672) was –3%.
A second study compared Grastek with placebo in 344 patients 5 through 17 years of age, of whom 26% had mild, intermittent asthma and 89% were sensitized to other allergens in addition to grass. Patients treated with Grastek showed a significant reduction in nasal and ocular symptoms, and reduced use of symptom-relieving allergy medication, as measured by a decrease in the TCS for the entire grass pollen season, compared with placebo. The difference for Grastek (n = 149) compared with placebo (n = 158) was –26%.
In the third study, 634 patients 18 through 65 years of age received Grastek or placebo for 3 consecutive years and were then observed for 2 years, during which they did not receive the study drug. Patients treated with Grastek showed a decrease in TCS throughout the grass pollen season during the 3 years of active treatment. This effect was sustained during the grass pollen season in the first year after discontinuation of Grastek, but not in the second year.
TCS differences per year (Grastek vs. placebo) were as follows:
- Year 1: –34% (n = 568)
- Year 2: –41% (n = 316)
- Year 3: –34% (n = 287)
- Post Treatment Year 1: –27% (n = 257)
Source: Merck; April 14, 2014.