SAN ANTONIO – Once-daily use of an investigational sublingual allergy immunotherapy liquid extracted from ragweed pollen resulted in highly significant and clinically meaningful improvements in ragweed allergy symptoms in a pivotal phase III multicenter trial involving more than 400 patients.
Mitchel L. Zoler/IMNG Medical Media
Dr. Peter S. Creticos
Given that subcutaneous immunotherapy is the mainstay of therapy in North America for seasonal allergic rhinoconjunctivitis and mild asthma that is unresponsive to pharmacotherapy, this ragweed sublingual allergy immunotherapy liquid (RW-SAIL) extract could represent an important and more convenient option for the management of allergic respiratory disease. Sublingual immunotherapy (SLIT) is used off label in the United States, because it is not approved by the Food and Drug Administration. SLIT is more commonly used in Europe, where studies have demonstrated varying degrees of success.
The current randomized, double-blind, placebo-controlled trial involved 429 adults between the ages of 18-55 years who had ragweed-induced allergic rhinitis, which had necessitated the use of antiallergy medication for at least 2 years and who were positive for ragweed pollen extract on puncture skin test reactivity. They were randomized to self-administered RW-SAIL (Greer Laboratories Inc.) or placebo beginning 8-16 weeks prior to and continued through the 2011 ragweed season.
Of these, 218 adults who were randomized to receive RW-SAIL experienced a 43% reduction in the primary study endpoint of total combined symptom and medication score (TCS) for the entire ragweed pollen season that followed treatment initiation, compared with 211 patients randomized to receive placebo. Breaking that response down by time of ragweed season, the treatment group patients experienced a 42% reduction in TCS during the 3 peak weeks of the season, a 42% reduction in the daily-symptom score (DSS) for the entire season, and a 41% reduction in the DSS during the 3 peak weeks of the season, compared with the placebo group, Dr. Peter Creticos, an allergy and asthma specialist in Warrenton, Va., and his colleagues reported in a poster at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
The RW-SAIL group also experienced a significantly greater increase from baseline in ragweed-specific IgG4 antibody, and in ragweed-specific IgE antibody, compared with the placebo group (0.99 vs. –0.1 mg/L, and 55.92 kU/L vs. 4.97 kU/L, respectively).
"Treatment with ragweed SAIL was well tolerated, with no deaths, systemic allergic reactions, or life-threatening events. No study subjects experienced anaphylaxis or required administration of epinephrine," the investigators wrote, noting that most adverse event were mild, and included headache, upper respiratory infection, and gastrointestinal effects. None of eight serious adverse events that occurred during the trial were attributable to the study drug.
The improvements achieved with RW-SAIL among the patients in the active-treatment group exceeded the criteria recently established by consensus panel reports, the investigators noted.
The findings have potentially important implications for the treatment of patients with ragweed allergy, the investigators said.
"Ragweed is the dominant seasonal aeroallergen for much of North America with observational studies showing sensitivity in about 25% of patients. It causes significant morbidity, is associated with disease sequelae and adversely impacts economic burden," they wrote.
The conventional subcutaneous approach to immunotherapy can also be burdensome, requiring a prolonged injection schedule that decreases compliance, discomfort associated with injections, and a recognized risk of anaphylaxis, they noted, concluding that RW-SAIL represents a safe and effective alternative treatment option for patients with ragweed allergy.
This study was funded by Greer Laboratories. Dr. Creticos disclosed relationships with Cercassia, Greer Laboratories, and Merck/Schering-Plough.