Asthma Control, Airway Mucus, and 129Xe MRI Ventilation After a Single Benralizumab Dose.

Background

Patients with eosinophilic asthma often report poor symptomatic control and quality of life. Anti-IL-5 therapy, including anti-IL-5Rα (benralizumab), rapidly depletes eosinophils in the blood and airways and also reduces asthma exacerbations and improves quality-of-life scores. In patients with severe asthma, eosinophilic inflammation-driven airway mucus occlusions have been measured using thoracic x-ray CT imaging. Pulmonary ¹²⁹Xe MRI ventilation defect percentage (VDP) also sensitively measures asthma airway dysfunction caused by airway hyperresponsiveness, remodeling, and luminal mucus occlusions. Using ¹²⁹Xe MRI and CT imaging together, it is feasible to measure both airway luminal occlusions and airway ventilation in relationship to anti-IL-5 therapy to ascertain the direct impact of therapy-induced eosinophil depletion on airway function.

Research Question

Does ¹²⁹Xe MRI detect airway functional responses to eosinophil depletion after a single benralizumab dose and do airway mucus occlusions mediate this response?

Study Design and Methods

MRI, eosinophil count, spirometry, oscillometry, Asthma Control Questionnaire (ACQ), Asthma Quality of Life Questionnaire (AQLQ), and St. George’s Respiratory Questionnaire were completed on day 0 and 28 days after a single 30-mg subcutaneous benralizumab dose. CT mucus plugs were scored on day 0, and MRI VDP was quantified on days 0 and 28.

Results

Twenty-nine participants (27 with baseline CT imaging) completed day 0 and day 28 visits. On day 28 after a single benralizumab dose, significantly improved blood eosinophil counts, VDP, ACQ 6 scores, AQLQ scores (all P < .001), and peripheral airway resistance (P = .04) were found in all participants. On day 28, significantly improved VDP and ACQ 6 scores also were found in the subgroup of nine participants with five or more mucus plugs, but not in the subgroup (n = 18) with fewer than five mucus plugs. Based on univariate relationships for change in ACQ 6 score, multivariate models were generated and showed that day 0 VDP (P < .001) and day 0 CT scan mucus score (P < .001) were significant variables for change in ACQ 6 score on day 28 after benralizumab injection.

Interpretation

¹²⁹Xe ventilation significantly improved in participants with uncontrolled asthma and in those with significant mucus plugging after a single dose of benralizumab.