Depigmented–polymerized mixed grass/birch pollen extract immunotherapy is effective in polysensitized patients


  • Edited by: Thomas Bieber

  • The results of this study were presented in part as oral presentations at the XXIIth World Allergy Congress (WAC) in Cancun, Mexico, 2011: Sager, Angelika; Biedermann, Tilo; Pfaar, Oliver: Comparison of Efficacy and Safety of a Dipigmented Polymerized Allergen Extract of Grass and Birch with Placebo in Patients With Type-1 Allergic Rhinoconjunctivitis. World Allergy Organization Journal. (2012): 5:20. Pfaar, Oliver; Biedermann, Tilo; Sager, Angelika: Seasonal Versus Symptom-based Evaluation of a Depigmented Grass-Birch Allergoid. World Allergy Organization Journal. (2012): 5: 21.



Although many patients with allergic rhinoconjunctivitis have symptoms due to sensitization with more than one pollen allergen, and mixed pollen extracts are widely used for allergen immunotherapy in practice, there are few published trials.


We performed a 2-year multicentre, double-blind, placebo-controlled trial of subcutaneous immunotherapy with mixed depigmented–polymerized birch and grass pollen extract in 285 patients with allergic rhinoconjunctivitis symptomatic during both birch and grass pollen seasons. Primary outcome was combined symptom and medication score (SMS) assessed by daily visual analogue scales (VAS). Analysis included a placebo-based analysis examining the effect of treatment only on days when placebo patients were symptomatic.


There was a significant reduction in median SMS for actively treated patients (median 5.70 (interquartile range 2.62–10.02) compared with 7.07 (3.47–10.71) for placebo, P = 0.0385). Rhinitis quality-of-life scores were significantly better for active compared with placebo, and other secondary endpoints were not significantly different. Placebo-based analysis showed a 33.7% reduced SMS at year 2 for active treatment compared with placebo on days when placebo patients were symptomatic. Both birch pollen- and grass pollen-specific IgG4 increased with active treatment.


This study shows efficacy of mixed pollen extracts for immunotherapy for patients symptomatic to both birch and grass pollen allergens. The relatively modest effect may reflect 50% dose reduction for each allergen in the mixture. It supports VAS for symptom assessment and placebo-based analysis as useful for the analysis of immunotherapy trials. The safety of modified extracts may allow study of mixed extracts without dose reduction to improve efficacy.