Effects of benralizumab on airway eosinophils in asthmatic patients with sputum eosinophilia

Abstract

Background: Many asthmatic patients exhibit sputum eosinophilia associated with exacerbations. Benralizumab targets eosinophils by binding IL-5 receptor α, inducing apoptosis through antibody-dependent cell-mediated cytotoxicity.

Objectives: We sought to evaluate the safety of benralizumab in adults with eosinophilic asthma and its effects on eosinophil counts in airway mucosal/submucosal biopsy specimens, sputum, bone marrow, and peripheral blood.

Methods: In this multicenter, double-blind, placebo-controlled phase I study, 13 subjects were randomized to single-dose intravenous placebo or 1 mg/kg benralizumab (day 0; cohort 1), and 14 subjects were randomized to 3 monthly subcutaneous doses of placebo or 100 or 200 mg of benralizumab (days 0, 28, and 56; cohort 2). Cohorts 1 and 2 were consecutive.

Results: The incidence of adverse events was similar between groups. No serious adverse events related to benralizumab occurred. In cohort 1 intravenous benralizumab produced a median decrease from baseline of 61.9% in airway mucosal eosinophil counts (day 28; placebo: +19.6%; P = .28), as well as an 18.7% decrease (day 21) in sputum and a 100% decrease (day 28) in blood counts. Eosinophils were not detectable in bone marrow of benralizumab-treated subjects (day 28, n = 4). In cohort 2 subcutaneous benralizumab demonstrated a combined (100 + 200 mg) median reduction of 95.8% in airway eosinophil counts (day 84; placebo, 46.7%; P = .06), as well as an 89.9% decrease (day 28) in sputum and a 100% decrease (day 84) in blood counts.

Conclusion: Single-dose intravenous and multiple-dose subcutaneous benralizumab reduced eosinophil counts in airway mucosa/submucosa and sputum and suppressed eosinophil counts in bone marrow and peripheral blood. The safety profile supports further development. Additional studies are needed to assess the clinical benefit in asthmatic patients.

Keywords: ADCC; AE; ATP; According to protocol; Adverse event; Antibody-dependent cell-mediated cytotoxicity; C-reactive protein; CPK; CRP; Creatine phosphokinase; Eosinophils; H&E; Hematoxylin and eosin; ICS; IL-5; IL-5 receptor; IL-5 receptors; IL-5R; IQR; Inhaled corticosteroid; Interquartile range; SABA; Short-acting β(2)-agonist; antibody-dependent cell-mediated cytotoxicity; asthma.

FIG 1

Study design. Cohorts 1 and 2 were consecutive.

FIG 2

Airway eosinophils (/mm²) for individual subjects (ATP population). a) Cohort 1 IV: placebo, n = 5; benralizumab 1 mg/kg, n = 8. b) Cohort 2 SC: placebo, n = 5; benralizumab 100 mg, n = 4; benralizumab 200 mg, n = 5. Dashed lines represent upper limit of normal (ULN) for airway eosinophil counts (22/mm²).^, c) Cohort 2 SC. Representative immunofluorescence photomicrographs showing mucosal and submucosal tissue sections obtained from one placebo subject and one benralizumab subject at screening and day 84. Green indicates anti-major basic protein-1-stained eosinophils and blue indicates 4′,6-diamidino-2-phenylindole (DAPI)-stained nuclei. The inserts show sections at x400 magnification.

FIG 2

Airway eosinophils (/mm²) for individual subjects (ATP population). a) Cohort 1 IV: placebo, n = 5; benralizumab 1 mg/kg, n = 8. b) Cohort 2 SC: placebo, n = 5; benralizumab 100 mg, n = 4; benralizumab 200 mg, n = 5. Dashed lines represent upper limit of normal (ULN) for airway eosinophil counts (22/mm²).^, c) Cohort 2 SC. Representative immunofluorescence photomicrographs showing mucosal and submucosal tissue sections obtained from one placebo subject and one benralizumab subject at screening and day 84. Green indicates anti-major basic protein-1-stained eosinophils and blue indicates 4′,6-diamidino-2-phenylindole (DAPI)-stained nuclei. The inserts show sections at x400 magnification.

FIG 2

Airway eosinophils (/mm²) for individual subjects (ATP population). a) Cohort 1 IV: placebo, n = 5; benralizumab 1 mg/kg, n = 8. b) Cohort 2 SC: placebo, n = 5; benralizumab 100 mg, n = 4; benralizumab 200 mg, n = 5. Dashed lines represent upper limit of normal (ULN) for airway eosinophil counts (22/mm²).^, c) Cohort 2 SC. Representative immunofluorescence photomicrographs showing mucosal and submucosal tissue sections obtained from one placebo subject and one benralizumab subject at screening and day 84. Green indicates anti-major basic protein-1-stained eosinophils and blue indicates 4′,6-diamidino-2-phenylindole (DAPI)-stained nuclei. The inserts show sections at x400 magnification.

FIG 3

Sputum eosinophils (%) for individual subjects (ATP population). a) Cohort 1 IV: placebo, n = 5; benralizumab 1 mg/kg, n = 7. One subject in the benralizumab group completed the study but did not have sputum induction after screening and is not included in this figure. An additional subject discontinued the study but provided sputum at screening and day 21; these data are included in this figure. b) Cohort 2 SC: placebo, n = 5; benralizumab 100 mg, n = 4; benralizumab 200 mg, n = 5. Dashed lines represent the inclusion criteria cut-off point for sputum eosinophil counts (2.5%).

FIG 3

Sputum eosinophils (%) for individual subjects (ATP population). a) Cohort 1 IV: placebo, n = 5; benralizumab 1 mg/kg, n = 7. One subject in the benralizumab group completed the study but did not have sputum induction after screening and is not included in this figure. An additional subject discontinued the study but provided sputum at screening and day 21; these data are included in this figure. b) Cohort 2 SC: placebo, n = 5; benralizumab 100 mg, n = 4; benralizumab 200 mg, n = 5. Dashed lines represent the inclusion criteria cut-off point for sputum eosinophil counts (2.5%).

FIG 4

Bone marrow eosinophil and neutrophils (%) for individual subjects (ATP population). Only subjects who consented to bone marrow aspiration and provided evaluable samples at screening and endpoint are included. a) Eosinophils. Cohort 1 IV: placebo n = 1, square with dashed line; benralizumab 1 mg/kg n = 4, diamond with solid line. Cohort 2 SC: benralizumab 100 mg n = 1, circle with solid line. b) Neutrophils and bands. Cohort 1 IV: placebo, n = 1; benralizumab 1 mg/kg, n = 4. Cohort 2 SC: benralizumab 100 mg n = 1.

FIG 5

Median (range) peripheral blood eosinophil and basophil counts (10³/μL) (ATP population). Subject numbers vary between timepoints depending on availability of data. At some timepoints all subjects in the benralizumab groups had the same value. a) Eosinophils. Cohort 1 IV. b) Eosinophils. Cohort 2 SC. c) Basophils. Cohort 2 SC.

FIG 5

Median (range) peripheral blood eosinophil and basophil counts (10³/μL) (ATP population). Subject numbers vary between timepoints depending on availability of data. At some timepoints all subjects in the benralizumab groups had the same value. a) Eosinophils. Cohort 1 IV. b) Eosinophils. Cohort 2 SC. c) Basophils. Cohort 2 SC.

FIG 5

Median (range) peripheral blood eosinophil and basophil counts (10³/μL) (ATP population). Subject numbers vary between timepoints depending on availability of data. At some timepoints all subjects in the benralizumab groups had the same value. a) Eosinophils. Cohort 1 IV. b) Eosinophils. Cohort 2 SC. c) Basophils. Cohort 2 SC.