Mepolizumab vs omalizumab in severe asthma: is one better than the other?

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  • In patients with severe asthma, mepolizumab (Nucala) appeared to be at least as effective as omalizumab (Xolair), with similar tolerability. 
Why this matters
  • There are no published comparisons of mepolizumab and omalizumab in patients with severe asthma.

Key results

  • Both drugs reduced the rate of clinically significant exacerbations and exacerbations requiring hospitalization vs placebo and standard of care. 
  • No difference between mepolizumab and omalizumab in the Overlap population (patients potentially eligible for both treatments), but trends favored mepolizumab (median rate ratio [RR], 0.66; 95% credible intervals [Crl], 0.37-1.19, and 0.19; 95% CrI, 0.02-2.32, respectively). 
  • Among Trial patients (potentially eligible for either treatment, mepolizumab yielded a greater reduction in clinically significant exacerbations vs omalizumab (RR, 0.63; 95% CrI, 0.45-0.89). 
  • Change in FEV1% predicted FEV1 were similar, with the point estimate favoring omalizumab in the Overlap population (mean difference, −0.98; 95% CrI, −6.35 to 4.36) and mepolizumab in the Trial population (mean difference, 0.24; 95% CrI, −3.61 to 4.10). 
  • Both drugs were largely comparable with placebo in terms of overall safety.

Study design

  • Indirect comparison using data from 4 randomized controlled trials. 
  • Funding: GSK.


  • Different measures used in mepolizumab and omalizumab trials. 
  • Asthma control and health-related QoL were not included.