Subcutaneous Mepolizumab Injection: An Adjunctive Treatment for Recalcitrant Allergic Fungal Rhinosinusitis Patients With Asthma

Background Allergic Fungal Rhinosinusitis (AFRS) is a non-invasive fungal disease that results from chronic allergic inflammation of the sinonasal mucosa. Failure to respond to mainstay medical therapies and sinus surgery leaves AFRS patients with limited alternatives and a decreased quality of life. Mepolizumab is a known IL-5 antagonist for patients with severe eosinophilic asthma. Objective To identify the efficacy of mepolizumab on improving Modified Lund-Kennedy (MLK) endoscopic scores in recalcitrant AFRS patients with asthma. Methods Retrospective chart review of 27 recalcitrant AFRS patients with asthma receiving a monthly mepolizumab injection between January 2017 and July 2019. Patients were evaluated endoscopically at baseline and at each follow-up visit every 6–8 weeks until their third visit. Secondary outcomes included SNOT-22 scores, serum eosinophil counts and the rate of prednisone rescues required in patients receiving mepolizumab compared to a retrospective control arm. Results Total median MLK scores improved significantly for all patients over three follow-up visits (6[4,7], 4[2,6], 5[2,6], 3.5[2.25,5]; p = 0.04). Amongst patients with a baseline polyposis score of 1 or more, combined MLK edema and polyposis sub-scores significantly improved (6[5.25,6], 3.5[2.25,5,75], 4[2.75,5.25], 4[3,4]; p = 0.02) versus patients with no polyposis (4[3,4], 3[1,4], 4[2,4], 3[0,4]; p = 0.90). Total SNOT-22 scores (56 vs 43; p = 0.04) and eosinophil counts (0.40 × 10 9 /L vs 0.00 × 10 9 /L; p < 0.01) decreased significantly when comparing baseline to last follow up. There was no significant difference in rate of prednisone rescues per 1000 person-days when comparing control to Mepolizumab population (1.19 vs 1.23; p = 1). Conclusion Mepolizumab injections administered once monthly as an adjunctive treatment for recalcitrant AFRS patients with asthma appear to significantly reduce endoscopic signs of inflammation, patient-reported symptomatology and serum eosinophil levels. Patients with evidence of more severe endoscopic inflammation appear to benefit the most. Adjunctive treatment with mepolizumab does not reduce the need for prednisone rescues.