⚠ Halozyme's Enzyme PatentsModerate threat

Merck & Co. (MRK) — threat to the moat

Halozyme has already stopped Keytruda's injection in Germany, and its American case decides whether the 2043 patent means anything.

The formulation meant to extend Keytruda's life is under patent attack. Halozyme has alleged that certain patents in its MDASE portfolio cover an ingredient in Merck's subcutaneous pembrolizumab1. In April 2025 it sued in New Jersey, alleging infringement of 15 patents2.

Halozyme dispute: counts and datesPatents asserted in New Jersey15US reviews decided, all claims unpatentable4German injunction appeal hearing19 November 2026UK patent revocation consentedMay 2026Merck Form 10-Q Q2 2026, contingencies note
Winning at home, blocked in Germany.

Merck has had real success in the United States. The Patent Trial and Appeal Board has issued decisions on four of the instituted post-grant reviews, finding every challenged claim unpatentable3, and in May 2026 Halozyme consented to revocation of its '622 patent in the United Kingdom4.

Germany went the other way. Halozyme won a preliminary injunction ordering Merck to refrain from distributing and offering Keytruda SC in Germany5; Merck has appealed, and the hearing is set for 19 November 20266.

The fight is spreading across Europe. Merck has filed revocation actions against Halozyme's '622 patent in the United Kingdom, France, Germany, the Netherlands, Denmark, Sweden and Switzerland7, and in the Dutch action Halozyme counterclaimed for infringement in further countries in February 20268. Each national court can reach its own answer.

The outcome that matters is the American case. A ruling that let the Halozyme patents stand in the United States would put the 2043 date in doubt; the German appeal on 19 November 2026 is the next signal to read.

References
  1. ReportedHalozyme has alleged that certain patents in its MDASE portfolio cover an ingredient in Merck's subcutaneous pembrolizumab.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  2. ReportedIn April 2025 it sued in New Jersey, alleging infringement of 15 patents.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  3. ReportedThe Patent Trial and Appeal Board has issued decisions on four of the instituted post-grant reviews, finding every challenged claim unpatentable, and in May 2026 Halozyme consented to revocation of its '622 patent in the United Kingdom.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  4. ReportedThe Patent Trial and Appeal Board has issued decisions on four of the instituted post-grant reviews, finding every challenged claim unpatentable, and in May 2026 Halozyme consented to revocation of its '622 patent in the United Kingdom.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  5. ReportedHalozyme won a preliminary injunction ordering Merck to refrain from distributing and offering Keytruda SC in Germany; Merck has appealed, and the hearing is set for 19 November 2026.
    Halozyme press release, 4 December 2025 - preliminary injunction in Germany against Keytruda SC. — December 2025 · publ. 4 December 2025 · source ↗
  6. ReportedHalozyme won a preliminary injunction ordering Merck to refrain from distributing and offering Keytruda SC in Germany; Merck has appealed, and the hearing is set for 19 November 2026.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  7. ReportedMerck has filed revocation actions against Halozyme's '622 patent in the United Kingdom, France, Germany, the Netherlands, Denmark, Sweden and Switzerland, and in the Dutch action Halozyme counterclaimed for infringement in further countries in February 2026.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
  8. ReportedMerck has filed revocation actions against Halozyme's '622 patent in the United Kingdom, France, Germany, the Netherlands, Denmark, Sweden and Switzerland, and in the Dutch action Halozyme counterclaimed for infringement in further countries in February 2026.
    Merck & Co. Form 10-Q for the quarter ended 30 June 2026 - segment profits on the recast basis, the Cidara and Terns acquisitions, the Halozyme litigation, China shipments, loss of exclusivity events and the balance sheet. — Q2 2026 · publ. 7 August 2026 · source ↗
Sources
Generated September 25, 2026