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Introduction: Despite careful design of dose ranging studies, full characterisation of dose-response for clinical endpoints is not always achieved. The absence of a dose-response for reduction in clinically significant exacerbations with mepolizumab in the primary analysis led to a meta-analysis using individualized weight-based measures of dose. Objectives: Evaluate weight-based measures of mepolizumab dose-response for reduction in annualized exacerbation rate. Methods: Inclusion of exacerbation data with dose and bodyweight information from two GSK funded mepolizumab severe asthma pivotal studies (DREAM and MENSA). Intravenous doses were converted to subcutaneous-equivalent dose using absolute bioavailability of 80 and 70% and normalized by individual bodyweight, body mass index and body surface area at baseline. Results: Description of the dose-response showed that although the maximal treatment effect was well-estimated, location of half-maximal efficacious dose (ED 50 ) was poor. Using a Bayesian analysis with informative priors for ED 50 (away from the pharmacological ED 50 (blood eosinophil reduction) [11 mg]), convergence was achieved. Posterior ED 50 distributions showed a shift in prior belief towards the pharmacological ED 50 with narrower credibility interval. The largest effects were noted for bodyweight-adjusted dose-response. Conclusions: Exacerbation data from studies DREAM and MENSA did not show a dose-response by conventional analysis unlike with Bayesian analysis which also showed consistency between the efficacy dose-response and the well-defined dose-response for pharmacology, with an ED 50 of approximately 0.17 mg/kg (12 mg).