Low rates of switching between biologics for severe asthma suggest clinicians are selecting appropriate and effective agents for their patients – but could there also be an element of under-switching?
A study of 3,531 adult patients from 11 countries with at least two biologics available found 79% remain on their first biologic for at least six months.
Not surprisingly given it was first to market in most jurisdictions, omalizumab was the most common agent (88%) for those first starting biologics in 2015. But by 2019, benralizumab was the most common agent (29.6%), then mepolizumab (24.5%) and dupilumab (23.1%).
The study found that in patients who switched, the most common first switch was from omalizumab to an anti–IL-5/5R (49.6%; n=187/377). The second most common switch was within class, adding or switching from one anti–IL-5/5R to another (30.8%; n=116/377).
For the few patients who switched more than once, the most common subsequent biologic switch was from one anti–IL-5/5R to another (44.4%; n=20/45).
The study found patients who switched biologics were more likely to have higher eosinophils, a history of more exacerbations and used more healthcare resources including ED visits and hospital stays.
“These factors may be associated with biologic switching simply because such patients are likely to qualify for more than one drug, eg subjects commencing omalizumab who are known to have a high BEC will have the option to switch to anti–IL-5/5R therapy, and within the eosinophilic phenotype, there is scope to switch between different anti–IL-5/5R agents,” it said.
By far the most common reason for switching a biologic was due to insufficient clinical efficacy (86.3%).
The study said the low percentage of patients who switched to another biologic suggested “appropriate biomarker-guided biologic selection and good clinical efficacy of the initial biologic”.
However a substantial proportion of patients qualify for more than one biologic agents and response to an untried alternative agent was clearly unknown, the study said.
“These findings naturally trigger the question: “Is the first biologic prescribed to a patient usually the best one for that individual, or are we under-switching?”
The investigators suggested there may be an element of settling for conservative response thresholds such as a 50% reduction in exacerbation rate rather than trying for something higher.
There was also a natural reluctance to take on the logistical hurdles, time and effort involved in switching to another biologic.