Director Denies Review of PGR Decision Holding All Remaining Challenged Claims of Halozyme's '520 PH20 Patent Unpatentable.

The proceeding

The proceeding is Merck Sharp & Dohme LLC v. Halozyme, Inc., PGR2025-00017, on U.S. Patent 12,110,520 B2. Merck petitioned for post-grant review of claims 1-35. Halozyme filed a statutory disclaimer of claims 3-5, 16, and 31-35, and the Board instituted trial on September 8, 2025 on the remaining claims 1, 2, 6-15, and 17-30.

Claim 1 covers a modified PH20 polypeptide with one or more amino acid modifications in an unmodified PH20 polypeptide of SEQ ID NOs: 3, 7 and 32-66, including an amino acid replacement at the position corresponding to residue 324 of SEQ ID NO:3 selected from A, D, H, M, N, R and S, where the modified polypeptide has at least 91% sequence identity to one of those sequences.

The final written decision

In a September 1, 2026 final written decision (Paper 106), the panel of Administrative Patent Judges Jeffrey N. Fredman, Susan L. C. Mitchell, and Cynthia M. Hardman held claims 1, 2, 6-15, and 17-30 unpatentable under 35 U.S.C. 112(a) for lack of written description and for lack of enablement. The Board found that Merck had not shown the claims unpatentable as obvious under 35 U.S.C. 103 over U.S. Patent 7,767,429 and Chao. On written description, the Board wrote that Halozyme "claims an immense number of mutations in the PH20 polypeptide, but provides insufficient guidance for a POSA as of 2012 to determine which, if any, of the untested multiple mutated forms will retain hyaluronidase activity." Before the decision, the Board denied Halozyme's motion to terminate in an order filed under seal (Paper 87); a public version was filed as Paper 96.

The Director Review order

Halozyme requested Director Review of the final written decision (Paper 108), and an authorized response was filed (Paper 109). In an October 30, 2026 order (Paper 110), the Director denied the request and granted Halozyme's motion to seal (Paper 97). A footnote states that Halozyme's earlier request for Director Review of the order denying its motion to terminate, filed under seal (Paper 98), was not considered.

Related matters

Halozyme asserts the '520 patent and fourteen other patents against Merck in Halozyme, Inc. v. Merck Sharp & Dohme Corp., No. 2:25-cv-03179 (D.N.J.), filed April 24, 2025. On August 6, 2026, the court administratively stayed that case pending the outcome of the patent reviews before the Patent Trial and Appeal Board and, if applicable, the Federal Circuit. The final written decision lists fourteen post-grant reviews, with numbers between PGR2025-00003 and PGR2025-00087, and three inter partes reviews (IPR2026-00312, IPR2026-00313, and IPR2026-00314) on related patents.

What to watch next

Watch for a notice of appeal to the Federal Circuit under 35 U.S.C. 141 and 37 C.F.R. 90.3. In the stayed New Jersey case, No. 2:25-cv-03179, the court set a joint letter for November 16, 2026 and a status conference for November 23, 2026 (D.I. 65).