Zydus and Formycon Petition for Post-Grant Review of All 21 Claims of a Merck and Agilent PD-L1 Scoring Patent.

The parties and the patent

The proceeding is Zydus Pharmaceuticals (USA) Inc. v. Merck Sharp & Dohme LLC, PGR2027-00003. The petitioners are Zydus Pharmaceuticals (USA) Inc., Zydus Lifesciences Limited, Zydus Lifesciences Global FZE, and Formycon AG. The petition names those four companies as the real parties in interest and, out of an abundance of caution, identifies 51 additional companies as real parties in interest. The petition names Merck Sharp & Dohme LLC and Agilent Technologies, Inc. as patent owners. U.S. Patent 12,529,702, titled Scoring Methods for Anti-PD Therapy Eligibility and Compositions for Performing Same, issued on January 20, 2026, from an application filed January 18, 2023. It claims priority through two earlier continuation applications to a provisional application filed April 1, 2016. Under 35 U.S.C. 321(c), a petition for post-grant review may be filed no later than nine months after the date of the grant of the patent. The petition was filed on October 20, 2026, nine months after the patent issued.

What the claims cover

Claim 1 covers a method for determining the eligibility of a subject having a malignancy for treatment with an anti-PD therapeutic agent. The method counts the viable PD-L1 positive tumor cells, PD-L1 negative tumor cells, and PD-L1 positive mononuclear inflammatory cells in a tumor tissue sample and calculates a combined positive score (CPS): PD-L1 positive tumor cells plus PD-L1 positive mononuclear inflammatory cells, divided by the sum of PD-L1 positive and PD-L1 negative tumor cells, times 100 percent. The subject is eligible when the CPS is above a threshold, and the agent comprises an anti-PD or anti-PD-L1 antibody or binding fragment. Dependent claim 18 lists agents including pembrolizumab and nivolumab. Claim 20 adds administering the agent when the CPS is above the threshold, and claim 21 sets that threshold at 1 percent or more.

The grounds

Five grounds challenge the claims: (1) claims 1 to 21 lack subject-matter eligibility under 35 U.S.C. 101; (2) claims 1 to 21 lack enablement under 35 U.S.C. 112(a); (3) claims 1 to 8, 12 to 14, and 16 to 21 are obvious under 35 U.S.C. 103 over WO 2014/165422 (WO422), Bellmunt, and Savas; (4) claim 9 is obvious over those three references and Herbst; and (5) claims 10, 11, and 15 are obvious over those three references and Dako, an immunohistochemistry guidebook. The petition calls WO422 Merck's own prior art reference. A technical expert's declaration supports the petition.

What to watch next

Under 37 CFR 42.207(b), the patent owners may file a preliminary response within three months of the notice according the petition a filing date. Under the USPTO's interim Director discretionary process, any discretionary denial brief from the patent owners is due within two months of that notice. Watch for the notice, those filings, and the institution decision.