Regeneron: The Rival Whose Drug Amgen CopiesNarrow moat

Amgen (AMGN) — moat facet

Amgen sells a copy of Regeneron's EYLEA while Regeneron sues to stop it and competes with Repatha and TEZSPIRE.

No rival shows the tangle of Amgen's relationships better than Regeneron. Amgen's PAVBLU is a biosimilar to Regeneron's EYLEA1, and it sold $700 million in 20252 and $287 million in the second quarter of 20263. Regeneron has sued: its complaint seeks, among other remedies, an injunction prohibiting the sale of PAVBLU in the United States4.

Amgen sales where Regeneron is the other party, 2025 ($M)3,016Repatha (vs PRALUENT)1,478TEZSPIRE (vs DUPIXENT)700PAVBLU (copy of EYLEA)Amgen FY2025 results release; relationships per Form 10-K FY2025
Three contests with one company.

The litigation is moving in Regeneron's direction for now. On 7 July 2026 the court in West Virginia granted in part Regeneron's motion to dismiss certain of Amgen's defences and counterclaims, dismissing with prejudice Amgen's antitrust counterclaims relating to one of the patents, while denying the motion on Amgen's prosecution laches defence5. PAVBLU remains on sale while the case continues.

Regeneron also meets Amgen twice more in the 10-K's competitor table: PRALUENT, sold with Sanofi, against Repatha, and DUPIXENT, also with Sanofi, against TEZSPIRE6. Repatha sold $3,016 million in 20257, and TEZSPIRE $1,478 million8.

So Regeneron is simultaneously the company whose product Amgen profits from copying, the plaintiff trying to stop it, and a rival in cholesterol and asthma. The relationship has no partnership side at all.

The case decides the value of the copying. An injunction would end PAVBLU's American sales, $280 million of its $287 million in the second quarter of 20269; a ruling for Amgen, or a settlement allowing continued sales, would leave the biosimilar business's best product intact until other copies arrive.

Moat trajectory: Holding steady

PAVBLU still on sale; litigation continuing.

The number that tests this moat
Reported
PAVBLU sales in the United States, latest quarter
$280M of $287M (Q2 2026)

What the Regeneron litigation puts at stake; an injunction would take the American line to zero.

Source: Amgen Q2 2026 results release ↗
References
  1. ReportedAmgen's PAVBLU is a biosimilar to Regeneron's EYLEA, and it sold $700 million in 2025 and $287 million in the second quarter of 2026.
    Amgen Form 10-K for fiscal 2025 - Item 1A risk factors, government pricing and legal proceedings including the IRS dispute. — FY2025 · publ. 13 February 2026 · source ↗
  2. ReportedAmgen's PAVBLU is a biosimilar to Regeneron's EYLEA, and it sold $700 million in 2025 and $287 million in the second quarter of 2026.
    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 ↗
  3. ReportedAmgen's PAVBLU is a biosimilar to Regeneron's EYLEA, and it sold $700 million in 2025 and $287 million in the second quarter of 2026.
    Amgen second-quarter 2026 results release, Form 8-K exhibit 99.1 - product sales performance: biosimilars. — Q2 2026 · publ. 4 August 2026 · source ↗
  4. ReportedRegeneron has sued: its complaint seeks, among other remedies, an injunction prohibiting the sale of PAVBLU in the United States.
    Amgen Form 10-K for fiscal 2025 - Item 1A risk factors, government pricing and legal proceedings including the IRS dispute. — FY2025 · publ. 13 February 2026 · source ↗
  5. ReportedOn 7 July 2026 the court in West Virginia granted in part Regeneron's motion to dismiss certain of Amgen's defences and counterclaims, dismissing with prejudice Amgen's antitrust counterclaims relating to one of the patents, while denying the motion on Amgen's prosecution laches defence.
    Amgen Form 10-Q for the quarter ended 30 June 2026 - product sales, the TAVNEOS proceeding, the IRS dispute, the BeOne stake and the balance sheet. — Q2 2026 · publ. 5 August 2026 · source ↗
  6. ReportedRegeneron also meets Amgen twice more in the 10-K's competitor table: PRALUENT, sold with Sanofi, against Repatha, and DUPIXENT, also with Sanofi, against TEZSPIRE.
    Amgen Form 10-K for fiscal 2025 - Item 1 patents, biosimilars and competitors. — FY2025 · publ. 13 February 2026 · source ↗
  7. ReportedRepatha sold $3,016 million in 2025, and TEZSPIRE $1,478 million.
    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 ↗
  8. ReportedRepatha sold $3,016 million in 2025, and TEZSPIRE $1,478 million.
    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 ↗
  9. ReportedAn injunction would end PAVBLU's American sales, $280 million of its $287 million in the second quarter of 2026; a ruling for Amgen, or a settlement allowing continued sales, would leave the biosimilar business's best product intact until other copies arrive.
    Amgen second-quarter 2026 results release, Form 8-K exhibit 99.1 - product sales performance: biosimilars. — Q2 2026 · publ. 4 August 2026 · source ↗
Sources
Generated September 28, 2026