Grastek (Timothy Grass Pollen Allergen Extract)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.


Approval Status:

Approved April 2014

Specific Treatments:

grass pollen-induced allergic rhinitis

General Information

Grastek contains pollen allergen extract from Timothy grass (Phleum pratense).The precise mechanisms of action of allergen immunotherapy are not known.

Grastek is specifically indicated for use in subjects ages 5 through 65 years as immunotherapy 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 IgE antibodies for Timothy grass or cross-reactive grass pollens.

Grastek is is supplied as a tablet for sublingual (under the tongue) administration. The recommended dose is one tablet daily. The first dose should be administered in a healthcare setting under the supervision of a physician with experience in the diagnosis and treatment of allergic diseases. The patient should be observed for at least 30 minutes to monitor for signs or symptoms of a severe systemic or a severe local allergic reaction. If the patient tolerates the first dose, subsequent doses may be taken at home. Treatment should be initiated at least 12 weeks before the expected onset of each grass pollen season and continue treatment throughout the season.

Clinical Results

FDA Approval
The FDA approval of Grastek in the treatment of allergic rhinitis with or without conjunctivitis in Timothy grass pollen allergic subjects 5 years of age and older, with or without mild asthma, was evaluated during the first grass pollen season in two trials of approximately 24 weeks treatment duration. The sustained effect of Grastek was evaluated in one trial conducted over 5 grass pollen seasons. All three trials were randomized, double-blind, parallel group, multicenter clinical trials. Subjects had a history of grass pollen induced rhinitis with or without conjunctivitis and sensitivity to Timothy grass pollen as determined by specific testing (IgE). In these three studies, subjects initiated Grastek or placebo approximately 12 weeks prior to the pollen season. In the long-term study, subjects received Grastek or placebo daily for 3 consecutive years and were followed for 2 years without treatment. Subjects were allowed to take symptom relieving medications. Efficacy was established by self-reporting of rhinoconjunctivitis daily symptom scores (DSS) and daily medication scores (DMS). Daily rhinoconjunctivitis symptoms included four nasal symptoms (runny nose, stuffy nose, sneezing, and itchy nose), and two ocular symptoms (gritty/itchy eyes and watery eyes). The rhinoconjunctivitis symptoms were measured on a scale of 0 (none) to 3 (severe). The sums of the DSS and DMS were combined into the Total Combined Score (TCS) which was averaged over the entire grass pollen season.
First Season Efficacy
Adults and Children
This placebo-controlled trial evaluated 1,501 subjects 5 through 65 years of age and compared Grastek to placebo administered as a sublingual tablet daily for approximately 24 weeks. TCS score over Entire season: Grastek: 3.24 versus placebo: 4.22. TCS score over Peak season: Grastek: 3.33 versus placebo: 4.22.
This double-blind clinical trial of approximately 24 weeks duration evaluated 344 pediatric subjects 5 to 17 years of age who were treated with either Grastek or placebo once daily. TCS score for Grastek: 4.62 versus for placebo: 6.25.
Sustained Effect
The sustained effect of Grastek was measured in a 5-year double-blind study. The study included 634 adults 18 to 65 years of age. Subjects received either Grastek or placebo daily for 3 consecutive years and were then observed for 2 subsequent years during which they did not receive study drug. Subjects treated with Grastek had a decrease in TCS throughout the grass pollen season during the three 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.

Side Effects

Adverse effects associated with the use of Grastek may include, but are not limited to, the following:

  • ear pruritus
  • oral pruritus
  • tongue pruritus
  • mouth edema
  • throat irritation

Mechanism of Action

Grastek contains pollen allergen extract from Timothy grass (Phleum pratense).The precise mechanisms of action of allergen immunotherapy are not known.

Additional Information

For additional information regarding Grastek or grass pollen-induced allergic rhinitis, please visit the Grastek web page.