Last updated: October 6, 2026
FASENRA, AstraZeneca’s benralizumab, is a commercially established biologic for severe eosinophilic asthma. Its sales have continued to grow, but the product faces increasing pressure from Dupixent, Nucala, Tezspire, and other biologics competing for the same specialist population. AstraZeneca’s principal growth opportunities are higher treatment penetration, self-administration, broader biologic use in severe asthma, and potential expansion into chronic obstructive pulmonary disease, or COPD.
FASENRA generated approximately $1.65 billion in 2024 revenue, representing about 3% of AstraZeneca’s total company revenue. Its U.S. biologic exclusivity period runs through November 2029, although patent rights and biosimilar entry timing may extend practical protection beyond or shorten the period depending on jurisdiction and litigation outcomes.
What is FASENRA and how does it work?
FASENRA is a humanized monoclonal antibody against the interleukin-5 receptor alpha, or IL-5Rα, expressed on eosinophils and basophils. By binding IL-5Rα and recruiting immune effector cells through antibody-dependent cell-mediated cytotoxicity, benralizumab produces rapid and near-complete depletion of circulating eosinophils.
The drug is administered subcutaneously:
| Product characteristic |
FASENRA detail |
| Active ingredient |
Benralizumab |
| Sponsor |
AstraZeneca |
| Drug class |
Anti-IL-5 receptor alpha monoclonal antibody |
| Initial U.S. approval |
November 14, 2017 |
| U.S. indication |
Add-on maintenance treatment for severe asthma with an eosinophilic phenotype |
| Standard adult dosing |
30 mg every four weeks for the first three doses, then every eight weeks |
| Administration |
Subcutaneous injection by healthcare professional or eligible self-administration |
| FDA pathway |
Biologics license application |
| Reference product status |
Reference biologic listed in the FDA Purple Book |
The eight-week maintenance schedule is a commercial advantage over some competing biologics that require dosing every two or four weeks. FASENRA’s use is generally concentrated in severe asthma patients who remain uncontrolled despite high-dose inhaled corticosteroids and additional controller therapy.
How has FASENRA revenue changed?
FASENRA revenue has followed a strong launch trajectory, supported by increasing biologic penetration in severe asthma and adoption of less frequent dosing.
| Fiscal year |
Approximate FASENRA revenue |
Year-over-year trend |
| 2019 |
$637 million |
Strong launch expansion |
| 2020 |
$886 million |
Approximately 39% growth |
| 2021 |
$1.05 billion |
Approximately 19% growth |
| 2022 |
$1.30 billion |
Approximately 24% growth |
| 2023 |
$1.58 billion |
Approximately 21% growth |
| 2024 |
$1.65 billion |
Approximately 5% growth |
AstraZeneca reports FASENRA within its respiratory and immunology portfolio. The figures above are based on AstraZeneca annual reporting and represent product sales or reported revenue, depending on the fiscal-year presentation.[1,2]
The trajectory shows three phases:
- Early launch expansion through 2021 as specialists adopted anti-eosinophil biologic therapy.
- Accelerated growth in 2022 and 2023 as biologic use expanded and FASENRA benefited from its eight-week maintenance schedule.
- Slower growth in 2024 as the severe asthma biologic market became more competitive and Dupixent gained share in overlapping patients.
At approximately $1.65 billion, FASENRA is a major AstraZeneca product but is not one of the company’s largest revenue drivers. The product represents roughly 3% of AstraZeneca’s total annual revenue, limiting company-wide financial concentration while preserving strategic value within respiratory medicine.
What drives FASENRA market growth?
The principal demand drivers are disease severity, eosinophil-guided treatment selection, improved diagnosis, and increasing willingness to use biologics earlier in the treatment pathway for eligible patients.
Severe asthma biologic penetration
A significant portion of severe asthma patients remain undertreated or untreated with biologic therapy. Growth depends less on new asthma patients than on identifying patients who have uncontrolled disease, frequent exacerbations, oral corticosteroid exposure, or elevated eosinophil counts.
FASENRA is positioned particularly strongly in patients with:
- High blood eosinophil counts
- Recurrent exacerbations
- Dependence on systemic corticosteroids
- Poor control despite inhaled corticosteroids and long-acting bronchodilators
- A preference for less frequent maintenance dosing
Dosing convenience
FASENRA is administered every eight weeks after the initial loading period. The dosing interval compares favorably with Nucala, which is generally administered every four weeks, and with some Dupixent regimens requiring administration every two weeks.
Dosing frequency does not determine prescribing independently. Physicians also consider atopic disease, nasal polyps, oral corticosteroid reduction, biomarker profile, payer restrictions, injection device, and prior authorization requirements.
Self-administration
The availability of a prefilled syringe for home administration reduces dependence on clinic-based injections and can improve persistence. AstraZeneca has continued to develop delivery options and patient-support infrastructure around FASENRA.
Self-administration also increases competition with Dupixent and Nucala, both of which have established home-use options and large patient-support programs.
How does FASENRA compare with Dupixent, Nucala, Tezspire, and Xolair?
FASENRA competes in a differentiated but overlapping biologic market.
| Product |
Sponsor |
Primary target |
Typical maintenance interval |
Competitive position |
| FASENRA |
AstraZeneca |
IL-5 receptor alpha |
Every 8 weeks after loading |
Strong eosinophil depletion and infrequent dosing |
| Nucala |
GSK |
IL-5 |
Every 4 weeks |
Established eosinophilic asthma franchise |
| Dupixent |
Sanofi/Regeneron |
IL-4 receptor alpha |
Usually every 2 weeks |
Broad indications, including atopic dermatitis and nasal polyps |
| Tezspire |
Amgen/AstraZeneca |
TSLP |
Every 4 weeks |
Biomarker-independent severe asthma positioning |
| Xolair |
Genentech/Novartis |
IgE |
Every 2 or 4 weeks |
Long-established allergic asthma product |
| Cinqair |
Teva |
IL-5 |
Every 4 weeks by infusion |
Limited commercial relevance relative to injected competitors |
Dupixent is the most important commercial competitor because of its broad label, strong growth, and use across type 2 inflammatory diseases. Tezspire competes through a broader biomarker proposition because it is not limited to eosinophilic disease selection in the same way as FASENRA.
FASENRA’s core commercial defense is the depth of eosinophil depletion, eight-week maintenance dosing, and an established specialist position in severe eosinophilic asthma. Its main weakness is narrower disease breadth than Dupixent and lower overall franchise scale than Dupixent or Nucala.
What is the FDA regulatory status of FASENRA?
FASENRA received FDA approval on November 14, 2017, as an add-on maintenance treatment for patients aged 12 years and older with severe asthma and an eosinophilic phenotype.[3]
The FDA subsequently expanded the product’s use to younger patients. In 2024, FASENRA received U.S. approval for patients aged six years and older with severe eosinophilic asthma, expanding the addressable pediatric population.[4]
The major unresolved regulatory growth opportunity is COPD. Earlier benralizumab COPD studies did not establish a broad indication. AstraZeneca later reported positive results from the MATINEE Phase III trial in a COPD population with elevated blood eosinophils and recurrent exacerbations.[5] A successful regulatory filing could materially increase FASENRA’s addressable market, but COPD approval would face a different competitive and reimbursement environment from severe asthma.
What patents protect FASENRA?
FASENRA is protected by biologic exclusivity, formulation and composition patents, antibody-related patent families, manufacturing rights, and possible method-of-use claims.
The key protection categories are:
| Protection category |
Relevance to FASENRA |
| Composition-of-matter and antibody claims |
Cover anti-IL-5Rα antibodies and related binding properties |
| Pharmaceutical composition claims |
Cover formulations containing benralizumab |
| Manufacturing claims |
May cover cell lines, purification, expression, or production processes |
| Method-of-use claims |
Cover treatment of eosinophilic asthma and related inflammatory conditions |
| Device and presentation claims |
May cover prefilled syringes, autoinjectors, or administration systems |
| Regulatory exclusivity |
Provides 12 years of U.S. reference-biologic exclusivity |
Because FASENRA is a biologic, it is not listed in the FDA Orange Book in the same manner as a conventional small-molecule drug. The reference product and eligible biosimilar information are handled through the Purple Book.[6]
The U.S. Biologics Price Competition and Innovation Act grants a reference biologic 12 years of exclusivity from first licensure. For FASENRA, that period generally runs from November 14, 2017, to November 14, 2029. A biosimilar applicant can pursue the statutory patent-exchange process before that date, but commercial approval cannot take effect before the applicable exclusivity period ends.
Patent expiration dates vary by family, jurisdiction, patent-term adjustment, terminal disclaimers, and claim scope. The practical protection profile therefore cannot be reduced to a single expiration date. The principal commercial cliff is likely to be shaped by the combination of November 2029 biologic exclusivity, surviving patent claims, biosimilar development timelines, and settlement outcomes.
Are there Paragraph IV challenges to FASENRA?
A conventional Paragraph IV challenge is generally not the expected pathway for FASENRA because Paragraph IV certifications apply primarily to abbreviated new drug applications for small-molecule products listed in the Orange Book.
A FASENRA biosimilar applicant would more likely use the FDA’s 351(k) pathway and participate in the BPCIA patent-dispute process. That process includes patent-information exchanges, infringement litigation, and possible settlement negotiations.
Publicly visible FASENRA competition has not produced the same level of prominent biosimilar patent litigation seen with older blockbuster biologics such as Humira, Stelara, or Enbrel. The absence of a major public challenge does not eliminate future risk. Biosimilar development can begin before the reference product’s 12-year exclusivity ends, and litigation may be filed closer to a commercial launch date.
When does FASENRA lose exclusivity?
FASENRA’s principal U.S. regulatory exclusivity expires on November 14, 2029. Actual biosimilar market entry may occur later if AstraZeneca enforces relevant patents or reaches a settlement that delays launch.
| Event |
Date or status |
| FDA approval |
November 14, 2017 |
| U.S. reference-biologic exclusivity |
Generally through November 14, 2029 |
| Earliest potential biosimilar approval timing |
Subject to BPCIA and FDA requirements |
| Commercial biosimilar entry |
Dependent on patents, litigation, settlement, and applicant strategy |
| Orange Book status |
Not the governing listing framework |
| Purple Book status |
Governing reference-biologic and biosimilar framework |
Outside the United States, exclusivity periods differ. European Union regulatory data protection and market protection operate under separate rules, and national patent rights can create different entry dates. Japan, Canada, Australia, and other markets also apply their own biologic approval and patent regimes.
What generic or biosimilar entry risks exist?
The near-term risk is competitive erosion rather than immediate generic substitution. FASENRA does not face traditional generic substitution because it is a monoclonal antibody. Future biosimilar entry would likely develop first in major biologic markets with significant reimbursement savings and established regulatory pathways.
The main risk factors are:
- Biosimilar developers targeting the IL-5 or IL-5Rα class
- Payer pressure on high-cost asthma biologics
- Formulary preference for Dupixent or Tezspire
- Loss of exclusivity in the United States after 2029
- Physician switching among biologics with similar clinical positioning
- Limited differentiation outside eosinophilic disease
- Potential price concessions before biosimilar entry
Biosimilar erosion may be slower than small-molecule generic erosion because biologics require clinical comparability, manufacturing capacity, physician acceptance, payer contracting, and immunogenicity monitoring. The pace will depend on whether one or more biosimilars launch simultaneously and whether payers establish interchangeability or preferred-product policies.
What patent litigation affects FASENRA?
No major publicly disclosed U.S. FASENRA patent litigation has created a known near-term launch event comparable with large small-molecule Paragraph IV cases. The relevant future litigation risk will likely arise from:
- Biosimilar applicants challenging antibody, formulation, manufacturing, or method-of-use patents.
- AstraZeneca enforcing patents in the BPCIA process.
- Device or administration patents affecting home-use presentations.
- International patent disputes involving local launch timing.
- Contract and licensing disputes involving manufacturing or commercialization rights.
Settlement agreements could permit a biosimilar launch before the last asserted patent expires. Such agreements are common in the biologic market, but no material FASENRA settlement should be assumed without a public filing or company disclosure.
Does AstraZeneca license FASENRA?
FASENRA was developed within AstraZeneca’s biologics organization, including MedImmune, AstraZeneca’s biologics research subsidiary. The product is commercially controlled by AstraZeneca rather than by an external license partner comparable to the Sanofi-Regeneron structure for Dupixent.
This ownership structure gives AstraZeneca control over pricing, manufacturing, regulatory strategy, lifecycle management, and global partnering. It also means FASENRA revenue is retained within AstraZeneca’s respiratory portfolio, subject to ordinary distribution and regional commercial arrangements.
How strong is the FASENRA patent estate?
FASENRA has a durable regulatory protection period and a multi-layer patent estate, but its long-term strength depends on claim validity, patent-term calculations, and the ability to defend process and use claims against biosimilar applicants.
| Strength factor |
Assessment |
| Regulatory exclusivity |
Strong through November 2029 in the United States |
| Product differentiation |
Moderate to strong in eosinophilic asthma |
| Dosing convenience |
Strong relative to four-week and two-week alternatives |
| Indication breadth |
Moderate; narrower than Dupixent |
| Biosimilar complexity |
Moderate to high because of biologic manufacturing |
| Patent visibility |
Requires family-by-family review across jurisdictions |
| COPD expansion potential |
Material but dependent on regulatory success |
| Long-term pricing power |
Vulnerable to biologic competition and payer contracting |
The estate is commercially meaningful but does not create an impenetrable barrier. The strongest protection is the combination of biologic exclusivity, manufacturing complexity, specialist adoption, and clinical familiarity.
What is the FASENRA generic launch scenario?
The most plausible U.S. launch sequence is:
- 2024-2027: continued branded competition and COPD lifecycle development.
- 2027-2029: increased biosimilar development, patent review, and potential BPCIA litigation.
- Late 2029 onward: first possible biosimilar approvals, subject to application timing and patent resolution.
- 2030-2032: potential broader biosimilar competition and payer-driven price erosion.
A single first entrant could initially achieve limited discounting if AstraZeneca retains strong formulary access. Multiple biosimilar entrants would create greater price pressure. The impact on AstraZeneca would depend on whether COPD approval expands the treated population before biosimilar entry.
What is the commercial outlook for FASENRA?
FASENRA’s financial trajectory remains positive but is entering a more mature phase. Severe asthma demand should continue to expand, while year-over-year growth is likely to remain below the early post-launch rate.
The most important upside catalyst is a successful COPD indication in an eosinophil-defined population. COPD is substantially larger than severe eosinophilic asthma, but the indication would expose FASENRA to more complex treatment algorithms, variable biomarker use, and competition from inhaled therapies and other biologics.
The principal downside risks are Dupixent’s scale, Tezspire’s biomarker-independent positioning, payer pressure, and the 2029 U.S. loss-of-exclusivity date.
Key Takeaways
- FASENRA generated approximately $1.65 billion in 2024 revenue.
- Revenue growth has slowed from early launch levels but remains positive.
- The product’s strongest differentiator is eight-week maintenance dosing after loading.
- Dupixent is the most important commercial competitor because of its broader indications and larger franchise.
- FASENRA’s U.S. biologic exclusivity generally runs through November 14, 2029.
- The Purple Book, not the Orange Book, is the relevant FDA framework for FASENRA biosimilar competition.
- Traditional Paragraph IV generic litigation is not the expected challenge model.
- COPD expansion is the principal potential growth catalyst.
- Biosimilar entry risk is likely to become more material after 2029.
- AstraZeneca retains control of FASENRA’s development, manufacturing strategy, regulatory program, and commercial economics.
FAQs about FASENRA market and patent risk
Is FASENRA a blockbuster drug?
Yes. FASENRA exceeds the conventional $1 billion annual-sales threshold for a blockbuster drug and generated approximately $1.65 billion in 2024 revenue.
Is FASENRA better than Dupixent?
Neither product is universally superior. FASENRA is strongly positioned for severe eosinophilic asthma and offers less frequent maintenance dosing. Dupixent has broader indications and may be preferred for patients with overlapping atopic dermatitis, nasal polyps, or other type 2 inflammatory conditions.
Can a generic version of FASENRA be substituted automatically?
No. A conventional generic is not expected because FASENRA is a biologic. Any future competitor would generally be a biosimilar, and automatic substitution would depend on FDA interchangeability status and state pharmacy laws.
Will FASENRA be approved for COPD?
AstraZeneca has reported positive Phase III COPD data for benralizumab in an eosinophil-defined population. Approval remains dependent on regulatory review and labeling decisions.
What happens to FASENRA sales after 2029?
Sales may face biosimilar and payer pressure after U.S. biologic exclusivity ends. The magnitude of erosion will depend on patent enforcement, biosimilar launches, COPD expansion, formulary positioning, and the number of competing products.
References
-
AstraZeneca PLC. (2024). Annual report and Form 20-F 2023. AstraZeneca.
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AstraZeneca PLC. (2025). Annual report and Form 20-F 2024. AstraZeneca.
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U.S. Food and Drug Administration. (2017). FDA approves new biologic treatment for severe asthma. FDA.
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U.S. Food and Drug Administration. (2024). FASENRA prescribing information. FDA.
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AstraZeneca PLC. (2024). Benralizumab MATINEE Phase III trial results in chronic obstructive pulmonary disease. AstraZeneca.
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U.S. Food and Drug Administration. (2024). Purple Book: Database of licensed biological products. FDA.
