Published online: December 16, 2017
Mepolizumab significantly reduces exacerbations in patients with severe eosinophilic asthma. To minimize unnecessary treatment, the early identification of patients likely to receive long-term benefit from treatment is important, but this identification must avoid selecting less severe patients and discontinuing patients benefiting from treatment.
A recent analysis by Gunsoy et al., published in The Journal of Allergy and Clinical Immunology: In Practice, assessed potential continuation rules for mepolizumab in addition to already defined initiation criteria of two or more exacerbations in the previous year and blood eosinophil counts of 150 cells/μL or more at initiation or 300 cells/μL or more in the previous year. The authors provide a method for assessing continuation rules that measure their impact while controlling for placebo responses to ensure that patients potentially benefiting from treatment are not wrongly discontinued.
Data from two randomized, double-blind, placebo-controlled studies of mepolizumab in severe eosinophilic asthma were used to evaluate potential rules assessed 16 weeks after mepolizumab treatment initiation based on blood eosinophils reduction, physician-rated response to treatment, lung function, symptoms, and exacerbation reduction.
There was no evidence of a reliable continuation rule to predict long-term exacerbation reduction from mepolizumab, as in most cases patients not meeting continuation rules still derived long-term benefit from mepolizumab. The assessment of exacerbations frequency showed promising results but did not meet predefined criteria for a useful rule; evaluation at 16 weeks was considered premature for an accurate evaluation of exacerbation reduction.
The authors conclude that unlike previously reported stopping rules for biologics in asthma, a viable stopping rule must control for placebo response. With this caveat, there is no evidence pointing to a potential short-term continuation rule for mepolizumab that can predict long-term exacerbation reduction, and that initiation criteria for mepolizumab treatment provides the best method for identifying a patient likely to respond to treatment.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.