A PHASE IIa clinical trial has investigated tozorakimab, an anti-IL-33 monoclonal antibody, in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) and chronic bronchitis, showing potential benefits in those with frequent exacerbations.
The FRONTIER-4 trial was a randomised, double-blind, placebo-controlled study assessing tozorakimab 600 mg, administered subcutaneously every 4 weeks for 24 weeks. The primary endpoint was the change in pre-bronchodilator (BD) FEV1 from baseline to week 12, with secondary outcomes including post-BD FEV1, time-to-first COPDCompEx event, and safety. Patients receiving dual or triple inhaled therapy were included, with subgroup analyses conducted based on exacerbation history.
Among 135 patients (tozorakimab n=67; placebo n=68), the primary endpoint was not met, as the improvement in pre-BD FEV1 at week 12 (least-squares mean [LSM]: 24 mL, 80% CI: −15, 63; p=0.216) was not statistically significant. However, post-BD FEV1 was significantly higher with tozorakimab (LSM: 67 mL, 80% CI: 17, 116; p=0.044). In a pre-specified subgroup of patients with ≥2 prior exacerbations, improvements in pre-BD (69 mL, 80% CI: 9, 130; p=0.072) and post-BD FEV1 (124 mL, 80% CI: 47, 201; p=0.020) were more pronounced.
Tozorakimab did not significantly reduce the risk of COPDCompEx events in the overall population (HR: 0.79, 80% CI: 0.57, 1.11; p=0.186), but a stronger effect was seen in patients with ≥2 prior exacerbations (HR: 0.61, 80% CI: 0.37, 1.00). Outcomes were similar in former and current smokers, and tozorakimab was well tolerated.
Although the primary endpoint was not met, these results suggest IL-33 inhibition may offer clinical benefits in patients with COPD at high risk of exacerbations. Further trials are needed to confirm its therapeutic potential in this subgroup.
Reference
Singh D et al. A phase 2a trial of the IL-33 mAb tozorakimab in patients with COPD: FRONTIER-4. Eur Respir J. 2025; DOI: 10.1183/13993003.02231-2024.
