Tezepelumab in the Framework of Use in Special Situations Before Commercialization: T-ROSS, a Retrospective Real-world Study in Spain

Purpose Tezepelumab, a fully human monoclonal antibody targeting the TSLP, was made available through a "foreign medication supply" (FMS) program in Spain prior to marketing authorization, for severe asthma (SA) patients, unresponsive to all other biologics or unable to receive them under national reimbursement conditions. This study aimed to describe patient characteristics and clinical outcomes in this highly challenging patient population. Methods We conducted a multicenter, observational, retrospective study in patients with severe asthma receiving tezepelumab under the FMS program. Data were collected over 12 months before tezepelumab initiation (index date) and up to the enrollment of the patient in the study afterward. Findings Of 39 available patients in the program, 33 were included, with a mean age of 51.9 years and a predominantly female population (84.9%). Median (interquartile range [25th-75th percentile]) follow-up was 12.6 (11.1-14.7) months. A substantial proportion (90.9%) had comorbidities. After initiation of tezepelumab, the annualized asthma exacerbation rate decreased from 3.2 to 1.3 per patient-year, and the proportion of patients without exacerbations increased from 18.8% to 53.1%. Lung function improved, with Forced Expiratory Volume in one second (FEV 1 ) increasing by 220 mL, FEV 1 % predicted increasing by 7.3%, and FEV 1 /FVC ( Forced Expiratory Volume in one second/Forced Vital Capacity) increasing from 0.6 to 0.7. Systemic corticosteroid use decreased from 48.8% to 24.2%. Clinical remission was achieved in 13.8% of this highly challenging patient population. Implications These results provide compelling real-world evidence that tezepelumab confers clinical benefits in this highly challenging patient population, including reduction in exacerbation rate, emergency room visits, and oral corticosteroid use, as well as improvements in lung function and asthma control. Future studies with larger sample sizes and different phenotypes need to be performed to further validate these findings. ClinicalTrials.gov identifier: NCT06487065.