OBJECTIVES: Mepolizumab, an anti–interleukin-5 monoclonal antibody, reduces disease flares in patients with hypereosinophilic syndrome (HES). Here, we assessed the impact of mepolizumab on symptom burden, health-related quality of life (HRQoL), and work productivity and impairment (WPAI).

METHODS: This placebo-controlled, double-blind, parallel-group, Phase III trial enrolled patients ≥12 years old with HES for ≥6 months, ≥2 flares in the previous 12 months, and BEC ≥1000 cells/μL at screening. Patients maintained ≥4 weeks stable HES therapy before randomization (1:1) to 4-weekly subcutaneous mepolizumab (300 mg) or placebo, plus baseline HES therapy, for 32 weeks. Change from baseline at Week 32 in symptom burden was assessed using a modified version of the memorial symptom assessment scale (MSAS-SF) (scale:0–4). Descriptive analyses of HRQoL and WPAI were performed using the short form-36 (SF-36) questionnaire, including an overall derived score (health utility index) and mental/physical component summary scores (scale:0–100) and the WPAI index general health questionnaire (scale:0–100%).

RESULTS: At Week 32, MSAS-SF total score improved in patients receiving mepolizumab (n=54) versus placebo (n=54) (median change: -0.19 vs 0.05, P=0.032). Global distress index score, physical symptom subscale score, and psychological symptom subscale score numerically improved with mepolizumab versus placebo but were not statistically significance (median changes: -0.23 vs 0.12, P=0.096; -0.13 vs 0.10, P=0.083; -0.22 vs -0.02, P=0.551, respectively). Likewise, a small numerical improvement in SF-36 score was observed with mepolizumab versus placebo (mean[SD] changes: utility index: 0.08[0.10] vs 0.04[0.08]; mental score: 3.55[9.03] vs 1.46[8.77]; physical score: 6.33[9.47] vs 3.81[5.75]). Mepolizumab treatment was also associated with numerically greater reductions in impairment while working, overall work impairment, and activity impairment versus placebo (mean[SD] % changes: -20.6[22.94] vs -2.4[21.66]; -17.0[39.63] vs -5.4[25.46]; -19.0[27.66] vs -3.7[24.98], respectively).

CONCLUSIONS: With mepolizumab treatment, patients with HES had a trend for an improvement in disease symptoms, HRQoL, and WPAI versus placebo.

FUNDING: GSK(200622/NCT02836496)