GSK's key drug mepolizumab injection gains fourth indication approval in China

On December 22, GSK announced that the National Medical Products Administration (NMPA) has approved mepolizumab injection for the maintenance treatment of adult patients with inadequately controlled chronic obstructive pulmonary disease (COPD) characterized by elevated blood eosinophils. This marks the first and only monthly-administered biologic approved in China for a broad COPD patient population with a blood eosinophil count (BEC) of ≥150 cells/μL.

This approval for the new indication is based on positive data from the Phase III MATINEE and METREX studies:

The MATINEE study evaluated the efficacy and safety of mepolizumab over 52–104 weeks in 804 COPD patients with evidence of type 2 inflammation (blood eosinophil count ≥300 cells/μL). Enrolled patients included COPD clinical phenotypes of chronic bronchitis only, emphysema only, both, or neither.

The METREX trial evaluated the efficacy and safety of mepolizumab over 52 weeks in 836 patients (randomized 1:1), divided into an eosinophilic phenotype group (blood eosinophil count at enrollment ≥150 cells/μL or ≥300 cells/μL in the past year) and a non-eosinophilic phenotype group (blood eosinophil count at enrollment <150 cells/μL with no evidence of ≥300 cells/μL in the past year).

In both the MATINEE and METREX trials, for patients with the eosinophilic phenotype, the addition of mepolizumab to standard triple inhaled therapy, compared with placebo, significantly reduced the annualized rate of moderate-to-severe acute exacerbations [MATINEE: rate ratio 0.79, 95% confidence interval [CI] 0.66, 0.94, p=0.01] (mepolizumab group AER=0.80 exacerbations/year vs. placebo group=1.01 exacerbations/year) [METREX: rate ratio 0.82, 95% CI 0.68, 0.98, adjusted p=0.04] (mepolizumab group AER=1.40 exacerbations/year vs. placebo group=1.71 exacerbations/year).

In a pre-specified secondary endpoint of the MATINEE study, the mepolizumab group showed a lower annualized rate of acute exacerbations leading to emergency department visits and/or hospitalizations compared to the placebo group [rate ratio 0.65, 95% CI (0.43-0.96) nominally significant after multiplicity adjustment] (mepolizumab group AER=0.13 exacerbations/year vs. placebo group=0.20 exacerbations/year).

Mepolizumab is a monoclonal antibody targeting interleukin-5 (IL-5), first approved by the U.S. FDA in November 2015. Its sales have increased year after year since approval. In 2024, the drug's sales reached $2.279 billion, a 10% year-over-year increase.

In China, mepolizumab had previously been approved for three indications: 1) as a maintenance treatment for severe eosinophilic asthma in adults and adolescents aged 12 years and older; 2) as an add-on maintenance therapy to intranasal corticosteroids for the treatment of adult patients with chronic rhinosinusitis with nasal polyps (CRSwNP) whose disease is inadequately controlled with systemic corticosteroids and/or surgery; and 3) for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA) in adults. The newly approved indication represents its fourth approved use in the country.

It is worth noting that, in anticipation of the future patent expiration of mepolizumab, GSK has developed a next-generation IL-5 antibody — depemokimab. As the first ultra-long-acting IL-5 antibody requiring injection only once every six months, it is designed to enhance patient compliance and convenience. The drug has already been submitted for regulatory approval in China.