Case Report: Extending dosing intervals of biologics in adults severe asthma: a case series.

Background: Biological therapies have improved the control of severe asthma. However, biological therapies are expensive. Therefore, the cost-effective use of these medications after achieving improved disease control warrants consideration. Methods: This retrospective case series analyzed 69 adult patients with asthma who received biological therapies at our department between 2009 and 2023. Among them, 11 patients underwent dosing interval extension. We collected data on their clinical characteristics, asthma control status, and changes in clinical parameters after interval extension. Results: At the time of dosing interval extension, the mean patient age was 62.1 years, with 5 female patients. Omalizumab was used in five cases, benralizumab in five, and dupilumab in one. The dosing intervals were extended by 1.5 to 2 times. The median duration from the initiation of biologics to interval extension was 7.0 months, with 6 patients undergoing extension within the first 7 months. One year after extension, asthma exacerbation occurred in only one patient receiving omalizumab. The frequency of exacerbations and the proportion of patients receiving oral corticosteroids (OCS) were decreased. The median ACT score remained at 25, while the median daily OCS dose decreased from 5.0 mg to 4.0 mg (prednisolone equivalent). The median % predicted FEV₁ changed from 84.9% to 78.3%. Conclusions: For patients whose asthma control improves after initiating biological therapy, extending the dosing interval may be a feasible treatment option. Given the retrospective, single-center design and small sample size, these findings are exploratory and generate hypotheses that require validation in larger, prospective studies.