An antibody against a single inflammatory signal cut COPD flare-ups in two trials
Tozorakimab, which blocks interleukin-33, lowered the rate of moderate or severe COPD exacerbations by about a third against placebo, without an eosinophil requirement to qualify.
| Group | Value (value) |
|---|---|
| OBERON — tozorakimab | 1.41 |
| OBERON — placebo | 2 |
| TITANIA — tozorakimab | 1.44 |
| TITANIA — placebo | 2.03 |
Two large trials have found that an antibody blocking a single inflammatory signal reduced the rate of flare-ups in chronic obstructive pulmonary disease, in patients who kept having exacerbations despite standard inhalers [s1]. The result, published in the New England Journal of Medicine, matters partly because the drug worked without selecting patients by their blood eosinophil count — the marker that gates most existing biologics for airway disease [s1].
COPD is a progressive lung disease, driven mostly by smoking, in which the airways narrow and periodically flare into an exacerbation — a stretch of worse breathlessness, coughing and mucus that can require steroids, antibiotics or hospital admission. Exacerbations do lasting damage and drive much of the disease's cost. Standard treatment is inhaled maintenance therapy, but many patients keep flaring on it. Tozorakimab is a monoclonal antibody that blocks interleukin-33, a signalling protein released by damaged airway cells that helps set off the inflammation behind those flares [s1].
What was tested
The two trials, OBERON and TITANIA, were designed as replicates — the same protocol run twice, so a result has to appear in both to be believed. Each enrolled adults with COPD who were current or former smokers and had at least one exacerbation in the previous year despite stable inhaled maintenance therapy [s1]. Crucially, there was no eligibility rule based on blood eosinophils, the allergy-linked cell that predicts response to most existing airway biologics [s1]. Patients were randomly assigned to add-on tozorakimab, 300 mg injected under the skin, or placebo, every four weeks for 52 weeks [s1].
The primary endpoint was unusual: the annualised rate of moderate or severe exacerbations over 52 weeks specifically among former smokers, with the overall population — current and former smokers together — as the first key secondary endpoint [s1].
What it found
Among former smokers, the annualised exacerbation rate was 1.34 with tozorakimab versus 1.90 with placebo in OBERON (rate ratio 0.71; 95% CI, 0.57 to 0.88; P=0.002), and 1.37 versus 2.07 in TITANIA (rate ratio 0.66; 95% CI, 0.55 to 0.80; P<0.001) [s1]. In the overall population the rates were 1.41 versus 2.00 in OBERON (rate ratio 0.70; 95% CI, 0.58 to 0.85; P<0.001) and 1.44 versus 2.03 in TITANIA (rate ratio 0.71; 95% CI, 0.59 to 0.84; P<0.001) [s1]. Across both trials and both populations, that is close to a one-third reduction in the rate of flares — a consistent signal, which replicate trials exist to test.
Adverse events were not more common on the drug: they occurred in 70.4% of the tozorakimab group versus 77.2% on placebo in OBERON, and in 80.1% versus 79.8% in TITANIA [s1].
Where it fits, and what is missing
A biologic that works regardless of eosinophil count would widen the pool of COPD patients a targeted drug could help, since the eosinophil-high group is a minority. That is the strategic point of these trials, and it is genuinely new. But two cautions belong alongside the numbers. A rate ratio around 0.70 is a meaningful reduction, not an elimination — patients on the drug still averaged more than one moderate or severe exacerbation a year [s1]. And exacerbation-rate trials do not, on their own, establish effects on lung-function decline, hospitalisation or survival, which take longer to read out. Both trials were funded by the manufacturer, AstraZeneca [s1].
The COPD result adds to a run of narrowly targeted respiratory drugs reaching phase 3, including an enzyme inhibitor for bronchiectasis and an antifibrotic for pulmonary fibrosis. Whether blocking interleukin-33 changes the disease's long arc, rather than trimming the flare count over a year, is the question the next trials will need to answer.
Sources
- Tozorakimab to Prevent COPD Exacerbations — The New England Journal of Medicine , September 8, 2026
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