Tozorakimab Opens a COPD Lane Other Biologics Shut

AstraZeneca’s tozorakimab cut moderate or severe COPD flare-ups by about 30% over 52 weeks in two Phase 3 trials that did not screen patients by eosinophil count. The full OBERON and TITANIA results went to the European Respiratory Society Congress in Barcelona and the New England Journal of Medicine on September 8, 2026.

The commercial fight sits in a thinner band. In a pooled look, patients with fewer than 150 eosinophils per microliter still had a 23% drop, and that group still has no licensed biologic.

The Patients Dupixent and Nucala Leave Out

Dupixent (dupilumab) from Sanofi and Regeneron is approved as add-on maintenance for adults with inadequately controlled COPD and an eosinophilic type. Its pivotal trials required eosinophils at 300 cells per microliter at screening, plus a productive cough and a history of at least two moderate flare-ups or one severe flare-up in the prior year.

GSK’s Nucala (mepolizumab) reached U.S. COPD patients in 2025 for an eosinophilic phenotype starting at 150 cells per microliter. GSK says about 70% of U.S. patients who still flare on inhaled triple therapy sit at or above that line, a pool it puts at more than a million people. Ruud Dobber, president of AstraZeneca’s biopharmaceuticals unit, said no biologic is available below 150.

Dr. Meilan Han, chief of pulmonary and critical care at University of Michigan Health and an investigator on the tozorakimab studies, put the gap in clinic language.

There’s still a huge number of patients who are not candidates for biologics with the current two approved drugs.

Dr. Meilan Han, University of Michigan Health

That is the group OBERON and TITANIA were built to include. There were no blood eosinophil cutoffs. Former smokers and current smokers both enrolled. Lung function ran across stages. The shot is a 300 mg under-the-skin dose every four weeks on top of inhaled maintenance therapy.

WHO CURRENT SHOTS DO NOT COVER

• Below 150: No approved COPD biologic; tozorakimab’s pooled cut in this band was 23% (rate ratio 0.77, 95% CI 0.62 to 0.94).
• 150 to 299: Nucala’s label can reach this eosinophilic type; Dupixent’s trials started at 300.
• 300 and above: Dupixent and Nucala both compete here, and tozorakimab’s pooled cut was 43% (rate ratio 0.57, 95% CI 0.44 to 0.74).
• No eosinophil test at all: AstraZeneca is arguing for a broad add-on label that would not require a cell-count gate to prescribe.

The 23% figure is the smallest of the three bands, and it is still statistically significant. A drug that widens who can get a biologic is a different product from one that only deepens the high-eosinophil shelf already stocked by Dupixent and Nucala.

OBERON and TITANIA Cut Flares Across Every Eosinophil Band

The two replicate trials randomized 2,306 adults with symptomatic COPD who had at least two moderate flare-ups or one severe flare-up in the 12 months before joining, despite at least three months of inhaled standard care. OBERON alone enrolled 1,132 people. The published comparison is 300 mg every four weeks versus placebo. The studies also tested a second dose regimen that was not the basis of the numbers released September 8.

The primary endpoint was the yearly rate of moderate or severe flare-ups in former smokers. The first key secondary endpoint was the same rate in the overall mix of current and former smokers. Moderate events needed steroids, antibiotics, or both. Severe events meant hospital care, an emergency visit, or death.

YEARLY FLARE-UP CUTS AT 300 MG EVERY 4 WEEKS

The add-on tozorakimab exacerbation rate results in former smokers were the regulatory spine. TITANIA’s former-smoker gap was 0.70 events per patient-year, which is one extra flare avoided for every 1.4 years of treatment on that trial’s numbers. Brian Lipworth, head of the Scottish Centre for Respiratory Research, ran the same arithmetic on the published rates and put the overall-population figure near 1.7 years.

Pooled across both trials, the ≥150 band (a post-hoc cut) showed a 34% reduction (rate ratio 0.66, 95% CI 0.56 to 0.78). The <150 and ≥300 bands were pre-specified. Benefit held in AstraZeneca’s telling across lung-function stages. A separate integrated analysis at the Barcelona meeting found a lower mucus-plug score, and the company called tozorakimab the first biologic to reduce mucus plugging in a broad COPD group. The poster did not release a single plug-score number in the accompanying statement.

Safety was described as favorable. The only adverse drug reaction listed was injection-site reaction.

A third Phase 3 study, MIRANDA, tested 300 mg every two weeks in 1,454 patients and met its flare-up endpoints earlier in 2026, including in former smokers and in the mixed smoking group. PROSPERO is a 1,713-patient extension looking at severe events over 104 weeks; those figures were not part of the September 8 package.

Blocking Two Forms of IL-33 Changes Who Qualifies

Tozorakimab is a monoclonal antibody against interleukin-33, an alarmin the airway lining dumps when smoke, infection, or pollution injures it. AstraZeneca says the antibody blocks both the reduced form of IL-33, which signals through ST2, and the oxidised form, which signals through a RAGE/EGFR complex. The pitch is a two-door lock: less inflammation, and a break in the mucus cycle that clogs airways.

IL-33 IN THIS PROGRAM

• The target: IL-33 sits upstream of several inflammatory paths, including some that do not run through eosinophils.
• The claim: Hitting both chemical forms is why the company thinks the shot can work in low-eosinophil disease, where IL-5 and IL-4/IL-13 drugs have little to grab.
• The dose on file: 300 mg every four weeks as add-on maintenance, now under U.S. Priority Review, with reviews also underway in the EU and China.

Dupixent blocks IL-4 and IL-13 signaling. Nucala binds IL-5. Both are built for type 2, eosinophil-high disease. Sharon Barr, AstraZeneca’s executive vice president for biopharmaceuticals R&D, said the IL-33 work “clinically validated the novel approach of targeting the signalling of the two forms of IL-33 to both decrease inflammation and disrupt the cycle of mucus dysfunction.”

Pascal Soriot, AstraZeneca’s chief executive, has been blunt about how little Wall Street wanted this mechanism. On the company’s second-quarter call he said, “Tozorakimab is a product nobody thought would work. We ourselves had a very low probability of success,” and that consensus forecasts had “almost zero” in them before the first Phase 3 headlines.

A Losing IL-33 Record Meets a Replicate Win

Other IL-33 and ST2 programs in COPD have been messy. Itepekimab, an IL-33 antibody from Regeneron and Sanofi, reduced moderate or severe flare-ups by 27% versus placebo at 52 weeks in AERIFY-1, with the signal concentrated in former smokers, then failed to cut events at a year in AERIFY-2. That split is why a clean pair of replicate wins matters more here than a single positive study.

COPD itself is large enough to absorb a new class if the label is broad. The World Health Organization still ranks it the 3.4 million COPD deaths in 2023 made it the third leading cause of death worldwide, about 6% of all deaths that year. Nearly 90% of COPD deaths in people under 70 are in low- and middle-income countries. Tobacco accounts for more than 70% of cases in high-income countries; in poorer countries household air pollution shares the load. AstraZeneca puts diagnosed patients near 400 million and says more than half still flare on inhaled standard care. In the United States the company estimates 16 million to 26 million people have the disease, diagnosed or not, and calls it the fifth-leading cause of death. U.S. flare-ups drive more than 2,500 emergency department visits a day. After a first severe flare, only 50% of patients live more than 3.5 years.

THE LUNA CLOCK

1. December 2024: The FDA grants Fast Track for tozorakimab in COPD, after an earlier Fast Track in November 2023 for severe viral lower-respiratory disease.
2. March 27, 2026: AstraZeneca says OBERON and TITANIA met their primary endpoints in former smokers and in the overall population.
3. First half of 2026: MIRANDA, the every-two-weeks study, also meets its flare-up endpoints.
4. September 8, 2026: Full 52-week rates, eosinophil-band analyses, and the mucus-plug poster land in Barcelona and in the journal.
5. First quarter of 2027: U.S. Prescription Drug User Fee Act date, after use of a Priority Review voucher.

Frank Sciurba, professor of pulmonary and critical care medicine at the University of Pittsburgh and chief investigator of the LUNA program, framed the eosinophil-agnostic result as the first of its kind.

The OBERON and TITANIA trials mark the first time we have seen a biologic in COPD achieve efficacy in a broad population across blood eosinophil thresholds, including in patients with baseline eosinophils below 150, and irrespective of smoking status.

Frank Sciurba, MD, University of Pittsburgh, LUNA chief investigator

How Prescribers Will Place the Shot

Han said she is likely to start patients with low eosinophil counts on tozorakimab if it is approved. She also said she does not yet know where it belongs relative to Dupixent and Nucala in high-eosinophil patients, because no head-to-head trials exist. She wants more subgroup cuts before she sequences the drugs in that crowded band, and she said the Global Initiative for Chronic Obstructive Lung Disease science committee will have to decide how guidelines treat an IL-33 option.

“I think it is a huge open question right now, both how providers are going to handle it, as well as how the GOLD committee will ultimately handle it,” Han said.

The high-eosinophil math is the awkward part of a success story. A 43% pooled cut at or above 300 cells looks competitive with the type 2 drugs already on the market. Nucala’s MATINEE trial posted a rate ratio of 0.79 and METREX a rate ratio of 0.82, in eosinophilic groups that are not matched to OBERON and TITANIA. Cross-trial comparisons of that sort are weak evidence. Clinics will still have to pick a first biologic when the cell count is high, and insurers will push for the cheaper or more familiar shot.

Preventing a steroid burst or a hospital night is the endpoint payers know how to count. It is not the same as giving back lost lung tissue or a longer walk. Fixed airflow obstruction and emphysema do not reverse on an alarmin antibody, and the Barcelona package was built around yearly flare rates, not a survival win. Health-technology bodies will price a biomarker-agnostic biologic against cost per flare avoided, especially if the low-eosinophil benefit stays in the low-20s.

WHAT WE KNOW

• Low-eosinophil signal: A pre-specified pooled 23% cut below 150 cells, with a confidence interval that stays below 1.
• Dosing on the file: 300 mg every four weeks is the regimen in the U.S. biologics license application.
• Safety so far: Injection-site reaction is the listed drug reaction from the 52-week pair.

WHAT IS UNCONFIRMED

• Guideline slot: GOLD has not placed an IL-33 antibody in its treatment algorithm.
• High-eosinophil order: No trial ranks tozorakimab against Dupixent or Nucala.
• Severe-event extension: PROSPERO’s 104-week severe-flare readout was not in the September 8 release.

Dobber said the medicine could “really change the treatment paradigm because of its broad utility.” That is a launch line. The clinic question is narrower: who gets the first dose when the blood count is 80, and who still gets Dupixent when it is 400.

Peak Sales Guidance Climbs Past $5 Billion

AstraZeneca raised its peak annual sales forecast for tozorakimab to more than $5 billion, up from an earlier $3 billion to $5 billion range, and has called it its largest respiratory product in waiting. Soriot said the figure can go higher because COPD is underdiagnosed and biologics are underused. “Maybe 10% of patients receive a biologic. Asthma is 30 to 40% depending on the country. So you can imagine the growth potential is very, very large,” he said.

The company still aims at $80 billion in total revenue by 2030. A heart-disease setback on Wainua in ATTR cardiomyopathy in July 2026 knocked a hole in that ladder. Tozorakimab is one of the rungs management is using to fill it. The antibody is also in a Phase 2 asthma study and a Phase 3 trial in severe viral lower-respiratory disease. Dobber has talked about possible work in bronchiectasis. None of those extra uses is on the U.S. COPD file.

THE COPD LOAD THE SHOT IS AIMED AT

• Global deaths: 3.4 million in 2023, third among causes of death, about 6% of all deaths.

Inhaled care: More than 50% of patients still flare on standard inhaled therapy, per AstraZeneca.

• U.S. emergency load: More than 2,500 COPD flare visits to emergency departments each day.
• After a severe flare: Half of patients are alive more than 3.5 years later.

Soriot’s 10% biologic-use figure is the tell. If even a slice of the patients below 150 cells start an injection, the addressable pool jumps past the eosinophilic niche Dupixent and Nucala already split. If payers confine the drug to that niche, or if GOLD keeps IL-33 behind a high cell-count step, the $5 billion case shrinks toward another me-too respiratory biologic.

The FDA’s decision window sits in the first quarter of 2027. Until then the low-eosinophil 23% is a published rate, not a prescription. Han’s patients in that band still leave the clinic with inhalers, antibiotics, and steroids, and with no antibody that a label will let her write.

Disclaimer: This article is news reporting and analysis of published trial results and company statements. It is informational only and is not medical advice, a treatment recommendation, or investment advice. Readers making care decisions should talk with a qualified physician or pulmonologist who knows their history, inhalers, and lab results; readers making financial decisions should consult a licensed financial adviser. Trial rates, regulatory dates, and sales forecasts reflect the sources cited as of September 8, 2026 and may change with new data, labeling, or coverage rules.