AstraZeneca and Amgen's TSLP Antibody Tezspire Approved in EU for Severe Asthma
EU Approval and Regulatory History
The European Union Executive Committee officially approved Tezspire (tezepelumab) from AstraZeneca (AZN) and Amgen (AMGN) on September 19, 2022. The approval is for add-on maintenance therapy in patients aged 12 years and older with severe asthma whose condition is inadequately controlled despite high-dose inhaled corticosteroids and other maintenance therapies. The EMA's Committee for Medicinal Products for Human Use (CHMP) adopted a positive opinion on July 21 of the same year, without a separate Advisory Committee (AdComm) vote. The FDA approved it on December 17, 2021, and Japan's Ministry of Health, Labour and Welfare approved it via PMDA review on September 26, 2022, completing entry into the three major regulatory regions.
TSLP Inhibition Mechanism and Clinical Evidence
Tezepelumab is a fully human IgG2 lambda monoclonal antibody that neutralizes thymic stromal lymphopoietin (TSLP), secreted by airway epithelium, and is the first TSLP inhibitor to reach approval and commercialization. Administered as a subcutaneous injection of 210 mg every four weeks, it is used as a long-term maintenance therapy, not an acute bronchodilator. In the Phase 3 NAVIGATOR trial involving 1,061 participants, tezepelumab added to standard care reduced annual asthma exacerbation rates by 56% compared to placebo, with statistical significance at p<0.001. Its efficacy was observed regardless of blood eosinophil levels, exhaled nitric oxide (FeNO), or allergic status, securing a broader prescribing base compared to existing biologics limited to specific inflammatory biomarkers.
Competitive Landscape and Market Implications
Standard care includes high-dose inhaled corticosteroids and long-acting beta-2 agonists, while biologics such as Sanofi (SNY) and Regeneron Pharmaceuticals (REGN)'s Dupixent (dupilumab, IL-4R alpha), GSK (GSK)'s Nucala (mepolizumab, IL-5), AstraZeneca's Fasenra (benralizumab, IL-5R alpha), and Roche (RHHBY)'s Xolair (omalizumab, IgE) compete in the market. These drugs have strong positions in allergic or type 2 inflammatory patients, but Tezspire accesses patients with the EU label unrestricted by phenotype or biomarker, including those with low eosinophil counts. The global top-eight severe asthma market was valued at $5.1 billion in 2023, with the five major European countries at $825.1 million, and the global market is projected to expand to $10.1 billion by 2033. Thus, the key to differentiation lies not in the novelty of the mechanism alone, but in the ability to convert patients outside the eligibility criteria of existing biologics into real-world prescriptions.
Commercial Structure and Performance
Under the revised 2020 agreement, both companies share global costs and profits equally, with AstraZeneca paying Amgen a mid-single-digit royalty rate first. AstraZeneca is responsible for global development and commercialization outside North America, while Amgen handles global manufacturing and U.S. revenue recognition. No new upfront payments, milestones, or equity investments were disclosed in connection with this approval. Tezspire achieved $486 million in sales in Q2 2026, a 42% year-over-year growth, already demonstrating strong prescription expansion in the commercial phase. Since the EU approval occurred in 2022, current investment decisions depend more on country-level reimbursement penetration, market share compared to Dupixent and Nucala, and label expansion rather than the approval news itself.
Tezspire reduced annual exacerbation rates by 56% in Phase 3 NAVIGATOR and secured an EU label unrestricted by biomarkers, expanding the prescription boundaries in the severe asthma market fragmented by Dupixent, Nucala, and Fasenra. The top-eight market size was $5.1 billion in 2023, with the five major European countries at $825.1 million, and is projected to reach $10.1 billion by 2033, with patient penetration in non-eosinophilic populations acting as a revenue lever. Sales of $486 million in Q2 2026 and a 42% growth rate validate commercial demand, but short-term performance hinges on European reimbursement and conversion rates from competing biologics. For researchers, it is a clinical validation of epithelium-derived TSLP inhibition at an upstream stage, and for the industry, the phenotype-independent label and potential for additional indications offer a model to extend the lifecycle of biologics. With equal cost and profit sharing and a priority mid-single-digit royalty structure, the long-term economic benefits of growth are distributed between the two companies.
Source: EMA (ema)