Limitations of model based dose selection for indacaterol in patients with chronic obstructive pulmonary disease.

OBJECTIVE: Indacaterol is a long-acting β-agonist (LABA) approved by FDA in 2011 at a dose of 75 μg once daily for the treatment of chronic obstructive pulmonary disease (COPD). During the review process for indacaterol approval, data were reanalyzed by FDA to evaluate the validity of the model based conclusions regarding dose selection. METHODS: The same dose response model applied by the sponsor was used to analyze a subset of the original data. Model predictions were compared with observed data to evaluate the model. Subgroups were created to visualize the relationship between key model parameters and covariates. The Emax model structure was evaluated for a meta-analysis. RESULTS: Patient-level analyses showed that the model based claim of additional benefit of 150 μg over 75 μg for more severe patients is not supported by the data. Mis-specified covariate model structures for key parameters contributed to this inconsistency. The assumed Emax model structure is not supported by the study-level data and the study-level analysis overestimates the incremental difference between two adjacent doses. CONCLUSIONS: Even though model based drug development is highly desirable, thorough model evaluation and justification is necessary to ensure the validity of related decisions.