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Routine bronchoscopy may clarify the treatment pathways for patients suffering from severe uncontrolled asthma (SUA) who are being considered for biologic therapy indicated for a T2 inflammation phenotype, according to a prospective study.

After receiving a bronchoscopy, a substantial number of people were found to have comorbidities aggravating asthma control: 21% had gastroesophageal reflux disease (GERD), 5% exhibited vocal chord dysfunction, and 3% had tracheal abnormalities. Some treatable traits were subsequently managed according to clinical practice, reported Borja Cosío, MD, PhD, respiratory specialist of University Hospital Son Espases in Palma, Spain, and coauthors.

Moreover, the 100 SUA patients in the study had initially been classified as T2-allergic (28%), T2-eosinophilic (64%), and non-T2 (8%) based on blood eosinophils, fractional exhaled nitric oxide (FeNO), and immunoglobulin E (IgE). With additional bronchoscopy, however, 88.9% of the T2-allergic group turned out to actually be T2-eosinophilic, a result of submucosal eosinophil findings during biopsy, according to the study published in .

Therefore, bronchoscopy findings could provide insight into more specialized treatments for uncontrolled asthma based on the individual patient.

"In the last decade, there has been increasing awareness of the importance of phenotypes and endotypes of asthma especially related to low and high T2 inflammation that guides the new therapeutic advances for severe patients," the researchers wrote.

Prior work has shown that people with T2 asthma are more responsive to corticosteroid therapies and biologics such as omalizumab (Xolair), mepolizumab (Nucala), reslizumab (Cinqair), benralizumab (Fasenra), and dupilumab (Dupixent).

Yet routine use of bronchoscopy for phenotyping prior to biologic therapy is controversial, Cosío and colleagues said. Arguing that this should be practiced more widely, they cited the poor correlation between blood and tissue eosinophils and the inaccessibility of other methods to assess airway eosinophilia, "whereas bronchoscopy is a routine procedure in every single respiratory department."

"Moreover, the ability of bronchoscopy to identify other causes of poor control such as GERD, vocal cord dysfunction, or endobronchial lesions and also to collect microbiological samples directly from the airways [supports] the routine use of bronchoscopy in the evaluation of every severe asthmatic prior to the indication of a biologic therapy," the group said.

Study authors found that bronchial aspirate cultures were able to isolate bacteria in 27% of patients and were able to isolate fungi in 14% of patients. The most common bacteria isolated were Pseudomonas aeruginosa and Staphylococcus aureus; the most common type of fungi was of the Aspergillus species.

One patient did experience moderate bleeding as a result of bronchoscopy, but this was treated and controlled during the course of the procedure. The authors stressed the overall safety of the procedure and its impacts on treatment options.

"We have shown that bronchoscopy is a safe procedure, able to better characterize inflammatory asthma inflammatory phenotypes but also diagnose alternative and treatable causes of poor asthma control, mainly clustered in upper airway disease and infection, that could preclude or postpone the use of biologics," they wrote.

The study included 100 consecutive SUA patients attending specialized asthma units at five teaching hospitals (median age 55 years, 58% men). All underwent bronchoscopy and had blood samples analyzed for blood eosinophil count and IgE levels. Patients also had skin-prick tests, FeNO, forced spirometry, and CT scans of the thorax performed.

Bronchial biopsies were performed in 68% of patients, leading to the discovery of eosinophils in 91% of samples.

Cosío's group reported that 7.8% of patients showed no eosinophils in their biopsy results despite initially falling into the conventional T2 phenotype. Three patients who received biopsies showed grade 2 to 3 eosinophils, despite having a non-T2 phenotype.

Study authors acknowledged that their sample of patients with a non-T2 asthma phenotype was very low, precluding solid conclusions about this group. Another limitation was that bronchial biopsies were not performed on all study participants, and local investigators may have interpreted samples differently. Finally, the authors noted that the study was not designed to measure impacts on asthma control.

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