In October 2026, the Patent Trial and Appeal Board issued four final written decisions in post-grant reviews that Merck brought against Halozyme patents. In each, all challenged claims were unpatentable for lack of written description and enablement under § 112(a). Obviousness over the ’429 patent and Chao wasn’t shown in any of the four.
Part 1 of 3
Patent 12,264,345, claims 1–17: final written decision, October 1, 2026 (Paper 89).
All challenged claims held unpatentable in each decision.
Not shown in any of the four decisions.
Patent 12,091,692, claims 1, 2, 5, and 7–33: final written decision, October 2, 2026 (Paper 96).
Patent 12,060,590, claims 1, 2, 6–15, and 17–30: final written decision, October 15, 2026 (Paper 100).
Patent 12,054,758, claims 1, 2, and 6–30: final written decision, October 15, 2026 (Paper 100).
Part 2 of 3
In each decision, the Board held all challenged claims unpatentable for lack of written description and enablement under § 112(a).
Obviousness over the ’429 patent and Chao wasn’t shown in any of the four. In the October 1, 2026 decision, indefiniteness also wasn’t shown.
Of the Board’s two trial types for patent challenges, only post-grant review can raise § 112. An inter partes review (IPR) is limited to §§ 102 and 103, based on patents and printed publications.
The four patents claim continuity to the same 2012 application and are drawn to modified PH20 hyaluronidase polypeptides.
Part 3 of 3
These are panel decisions. None is designated precedential or informative. As of October 29, 2026, no party had requested Director Review, and the time to request it hadn’t run.
The takeaway
For a newly issued patent, weigh § 112 grounds early. A post-grant review petition must be filed within nine months after the patent issues.
Precedential decisions bind the Board within their designated scope. Informative decisions show the Office’s reasoning but do not bind the Board. Court opinions are cited for what they decided; later history was checked on the date shown above.