Methods: 473 grass pollen allergic adults with a Retrospective Rhinoconjunctivitis Total Symptom Score of >12 (scale 0-18) during the previous pollen season were randomized in a DBPC study to receive 300IR SLIT tablet or placebo, once-daily starting 4 months before and continuing through the 2009 grass pollen season. The primary efficacy variable was the daily Combined Score (CS, scale 0-3), which integrates symptoms and rescue medication use. Secondary efficacy assessments included the daily Rhinoconjunctivitis Total Symptom Score (RTSS), daily Adjusted Symptom Score (AdSS, which adjusts the RTSS for rescue medication use) and daily individual rhinoconjunctivitis symptom scores. The primary efficacy endpoint, the daily CS during the pollen period while on treatment, was analyzed using a repeated measures ANCOVA model, as were the above secondary efficacy endpoints . The safety of the treatment was documented by means of adverse event reporting, laboratory data and physical examination findings.
Results: The 300IR group showed a relative improvement in daily CS vs. placebo of -28.2% (relative difference in LS Means, 95% CI [-43.4%; -13.0%], p=0.0003). Significant improvements in RTSS and AdSS were consistent with previous European studies. There were also significant improvements in the individual symptoms: sneezing, rhinorrhea, nasal congestion, itchy eyes and watery eyes. The 300IR SLIT tablet was generally well tolerated. The most commonly reported treatment-emergent adverse events (TEAEs) in the 300IR group were application site-reactions: oral pruritus, throat irritation, and nasopharyngitis. No drug-related serious TEAEs were reported. The overall safety profile of 300 IR SLIT tablet was consistent with that observed in European studies.
Conclusions: The 300IR SLIT tablet showed clinically meaningful efficacy, with significant improvements on the primary and secondary endpoints. The treatment was well-tolerated. Overall, the results in United States are consistent with European observations.