TEZSPIRE: Half Sold by AstraZenecaNarrow moat

Amgen (AMGN) — moat facet

TEZSPIRE went from zero to $1.5 billion in four years, and AstraZeneca both sells it abroad and competes with it through FASENRA.

TEZSPIRE is a severe-asthma drug that grew from nothing in 2021 to $1,478 million in 20251. It sold $170 million in 2022, $567 million in 2023 and $972 million in 202423, and $486 million in the second quarter of 2026, up 42%4.

TEZSPIRE sales ($M)1702022567202397220241,4782025Amgen FY2023 and FY2025 results releases
From zero to $1.5 billion in four years.

It is a partnership. The 10-K says the two companies share global costs, profits and losses equally after payment by AstraZeneca of a mid-single-digit royalty to Amgen5. Amgen records American sales and AstraZeneca records sales elsewhere6, so half the drug's profit belongs to the partner however fast it grows.

Amgen describes TEZSPIRE as a first-in-class antibody that works on the primary source of inflammation: the airway epithelium7. It is approved for severe uncontrolled asthma in more than 70 countries and for chronic rhinosinusitis with nasal polyps8. It competes against a list of established biologics that the 10-K names: DUPIXENT from Regeneron and Sanofi, FASENRA from AstraZeneca, NUCALA from GSK and XOLAIR from Genentech and Novartis9. AstraZeneca thus sells TEZSPIRE abroad and FASENRA against it.

Its patent protection is long, to February 2034 for the polypeptides in the United States10.

The accounting follows the partnership. In the second quarter of 2026 Amgen reported all $486 million of TEZSPIRE's sales as American, with nothing abroad11, because AstraZeneca records the sales outside the United States12. The reported figure therefore understates the drug's worldwide size.

TEZSPIRE is one of the in-house drugs carrying Amgen's growth. The figure to watch is its quarterly growth, 42% in the second quarter of 202613; if it holds above 25% through 2027, the drug is taking share from the older biologics, and if it falls toward 10% it will have settled as one option among five.

Moat trajectory: Widening

Up 42% in Q2 2026.

The number that tests this moat
Reported
TEZSPIRE sales, latest quarter
$486M, +42% (Q2 2026)

Share taken from older asthma biologics; growth near 10% would mean it has settled as one of five.

Source: Amgen Q2 2026 results release ↗
⚠ Threats to the moat
⚠ THREAT 01
Four Established Asthma Biologics
TEZSPIRE competes with four established asthma biologics, one of them sold by its own international partner.
References
  1. ReportedTEZSPIRE is a severe-asthma drug that grew from nothing in 2021 to $1,478 million in 2025.
    Amgen fourth-quarter and full-year 2025 results release, Form 8-K exhibit 99.1 - product sales for 2024-2025, non-GAAP EPS and 2026 guidance. — FY2025 · publ. 3 February 2026 · source ↗
  2. ReportedIt sold $170 million in 2022, $567 million in 2023 and $972 million in 2024, and $486 million in the second quarter of 2026, up 42%.
    Amgen fourth-quarter and full-year 2023 results release, Form 8-K exhibit 99.1 - product sales for 2022-2023. — FY2023 · publ. February 2024 · source ↗
  3. ReportedIt sold $170 million in 2022, $567 million in 2023 and $972 million in 2024, and $486 million in the second quarter of 2026, up 42%.
    Amgen fourth-quarter and full-year 2025 results release, Form 8-K exhibit 99.1 - product sales for 2024-2025, non-GAAP EPS and 2026 guidance. — FY2025 · publ. 3 February 2026 · source ↗
  4. ReportedIt sold $170 million in 2022, $567 million in 2023 and $972 million in 2024, and $486 million in the second quarter of 2026, up 42%.
    Amgen second-quarter 2026 results release, Form 8-K exhibit 99.1 - product sales performance: inflammation, rare disease and established products, and sales by region. — Q2 2026 · publ. 4 August 2026 · source ↗
  5. ReportedThe 10-K says the two companies share global costs, profits and losses equally after payment by AstraZeneca of a mid-single-digit royalty to Amgen.
    Amgen Form 10-K for fiscal 2025 - Item 1 business: products, collaborations, staff and pipeline. — FY2025 · publ. 13 February 2026 · source ↗
  6. ReportedAmgen records American sales and AstraZeneca records sales elsewhere, so half the drug's profit belongs to the partner however fast it grows.
    Amgen Form 10-K for fiscal 2025 - Item 1 business: products, collaborations, staff and pipeline. — FY2025 · publ. 13 February 2026 · source ↗
  7. ReportedAmgen describes TEZSPIRE as a first-in-class antibody that works on the primary source of inflammation: the airway epithelium.
    Amgen Form 10-K for fiscal 2025 - Item 1 business: products, collaborations, staff and pipeline. — FY2025 · publ. 13 February 2026 · source ↗
  8. ReportedIt is approved for severe uncontrolled asthma in more than 70 countries and for chronic rhinosinusitis with nasal polyps.
    Amgen Form 10-K for fiscal 2025 - Item 1 business: products, collaborations, staff and pipeline. — FY2025 · publ. 13 February 2026 · source ↗
  9. ReportedIt competes against a list of established biologics that the 10-K names: DUPIXENT from Regeneron and Sanofi, FASENRA from AstraZeneca, NUCALA from GSK and XOLAIR from Genentech and Novartis.
    Amgen Form 10-K for fiscal 2025 - Item 1 patents, biosimilars and competitors. — FY2025 · publ. 13 February 2026 · source ↗
  10. ReportedIts patent protection is long, to February 2034 for the polypeptides in the United States.
    Amgen Form 10-K for fiscal 2025 - Item 1 patents, biosimilars and competitors. — FY2025 · publ. 13 February 2026 · source ↗
  11. ReportedIn the second quarter of 2026 Amgen reported all $486 million of TEZSPIRE's sales as American, with nothing abroad, because AstraZeneca records the sales outside the United States.
    Amgen second-quarter 2026 results release, Form 8-K exhibit 99.1 - product sales performance: inflammation, rare disease and established products, and sales by region. — Q2 2026 · publ. 4 August 2026 · source ↗
  12. ReportedIn the second quarter of 2026 Amgen reported all $486 million of TEZSPIRE's sales as American, with nothing abroad, because AstraZeneca records the sales outside the United States.
    Amgen Form 10-K for fiscal 2025 - Item 1 business: products, collaborations, staff and pipeline. — FY2025 · publ. 13 February 2026 · source ↗
  13. ReportedThe figure to watch is its quarterly growth, 42% in the second quarter of 2026; if it holds above 25% through 2027, the drug is taking share from the older biologics, and if it falls toward 10% it will have settled as one option among five.
    Amgen second-quarter 2026 results release, Form 8-K exhibit 99.1 - product sales performance: inflammation, rare disease and established products, and sales by region. — Q2 2026 · publ. 4 August 2026 · source ↗
Sources
Generated September 28, 2026