Allergy Skin Testing and Eosinophils
Skin prick testing (SPT) was positive to at least one of the thirty aeroallergens tested at baseline in about half the patients in both the benralizumab and placebo groups. Benralizumab treated patients with six or more positive skin tests had minimal improvement in endoscopic nasal polyps score, whereas all five subjects with two or less positive SPT improved. As seen in Figure 5A, there was an inverse correlation between the number of skin tests positives and endoscopic NP score improvement (P=0.023). Total serum serum IgE and polyp score reduction were not correlated (P=0.071).
Benralizumab reduced blood eosinophil counts in all treated patients (100%). The absolute eosinophil count for the benralizumab treated group decreased from 698/µl (SD=412.7) to 20/µl (SD=49.7) at week twenty (P<0.001). Mean eosinophil count for the placebo group decreased slightly from 846/µl (SD=592.6) to 650/µl (SD=552.8) but was not significant (P=0.106). Blood eosinophils were undetectable in ten of the twelve patients treated with benralizumab but remained elevated in all subjects in the placebo group. In contrast to what was seen for allergen SPT, higher blood eosinophil counts correlated with better reduction in polyp scores, although this trend did not reach statistical significance (P=0.301). Nonetheless, as seen in Figure 5B, all benralizumab treated patients with blood eosinophil counts greater than 700/µl improved.