# Four post-grant reviews: § 112(a) won, obviousness lost.

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.

Sources checked October 29, 2026

**4 of 4** post-grant reviews held every challenged claim unpatentable under § 112(a). Obviousness wasn’t shown in any of them.

## Four decisions, one result

Patent 12,264,345, claims 1–17: final written decision, October 1, 2026 (Paper 89). Patent 12,264,345

Patent 12,091,692, claims 1, 2, 5, and 7–33: final written decision, October 2, 2026 (Paper 96). Patent 12,091,692

Patent 12,060,590, claims 1, 2, 6–15, and 17–30: final written decision, October 15, 2026 (Paper 100). Patent 12,060,590

Patent 12,054,758, claims 1, 2, and 6–30: final written decision, October 15, 2026 (Paper 100). Patent 12,054,758

## What the Board held

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. Patent 12,264,345

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. 35 U.S.C. §§ 311, 321

The four patents claim continuity to the same 2012 application and are drawn to modified PH20 hyaluronidase polypeptides. Patent 12,264,345

## Read the limits

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. 35 U.S.C. § 321(c)

## Related stories

- [Post-grant review’s favored status stops at the merits.](https://postgrantproceeding.com/insights/d05-a-pgr-gets-a-head-start)
- [Bio/pharma’s higher institution rate rests on 71 decisions.](https://postgrantproceeding.com/insights/t06-bio-pharma-petitions-were-instituted-more-often-in-fy2026)
- [2026 reexamination requests on listed drug patents: 4 of 794.](https://postgrantproceeding.com/insights/t08-few-2026-reexams-target-listed-drug-patents)

## Sources

- S103. Merck Sharp & Dohme LLC v. Halozyme, Inc., No. PGR2025-00052, Paper 89 (P.T.A.B. October 1, 2026) (final written decision) (Patent 12,264,345, claims 1–17). https://data.uspto.gov/ptab-trials
- S104. Merck Sharp & Dohme LLC v. Halozyme, Inc., No. PGR2025-00046, Paper 96 (P.T.A.B. October 2, 2026) (final written decision) (Patent 12,091,692, claims 1, 2, 5, 7–33). https://data.uspto.gov/ptab-trials
- S105. Merck Sharp & Dohme LLC v. Halozyme, Inc., No. PGR2025-00024, Paper 100 (P.T.A.B. October 15, 2026) (final written decision) (Patent 12,060,590, claims 1, 2, 6–15, 17–30). https://data.uspto.gov/ptab-trials
- S106. Merck Sharp & Dohme LLC v. Halozyme, Inc., No. PGR2025-00030, Paper 100 (P.T.A.B. October 15, 2026) (final written decision) (Patent 12,054,758, claims 1, 2, 6–30). https://data.uspto.gov/ptab-trials
- S13. Federal patent statutes, 35 U.S.C. §§ 253(a), 301, 302, 303(a), 311–315, 317 and 321–325. Reproduced in MPEP Appendix L (currency date stated by the appendix: Jan. 31, 2024). https://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html

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.

General information about published decisions, not legal advice. Reading it does not create an attorney-client relationship.