On March 4, 2024, Merck Sharp & Dohme, LLC (“Merck”) filed four IPRs challenging The Johns Hopkins University (“JHU”) patents covering methods of treatment using pembrolizumab, which Merck sells under the trade name Keytruda®.  The four IPRs are IPR2024-00622 challenging U.S. Patent No. 10,934,356; IPR2024-00623 challenging U.S. Patent No. 11,325,974; IPR2024-00624 challenging U.S. Patent No. 11,325,975; and IPR2024-00625 challenging U.S. Patent No. 11,339,219; as being anticipated by and obvious over the prior art.

According to a November 2022 Complaint filed by Merck against JHU (1:22-cv-03059 (D. Md.)), which relates to the patents at issue in the IPRs, Merck and JHU had a joint research collaboration to conduct a clinical study using Keytruda®Merck alleged that after concluding the study, “JHU obtained issuance of United States patents citing the joint research study, but inaccurately claiming that the purported inventions arose prior to, and independent of, the collaboration with Merck. Further, JHU improperly exclusively licensed these patents to others. JHU then tried to use these patents to demand payment from Merck for use of Keytruda.”  Merck’s Complaint alleges breach of contract, non-infringement of the JHU patents, and promissory estoppel.  JHU counterclaimed for infringement of the JHU patents that are the subject of the above IPRs along with U.S. Patent No. 11,591,393 (which was subject to an IPR challenge by Merck in November 2023 (IPR2024-00240)), and various pending U.S. patent applications.  The litigation is ongoing and the IPR is awaiting an Institution Decision.

Keytruda® was the world’s top selling drug in 2023, with $25 billion in world-wide sales.

We continue to monitor the Keytruda® IPRs and litigation and will provide updates as they become available.  For more information about these and other biosimilar and biologic drug patent disputes, visit BiologicsHQ.



The author would like to thank April Breyer Menon for her contributions to this article.


    Information contained in the Venable BiologicsHQ database relates to FDA-approved drug products listed in the CDER Purple Book or on the FDA website ( Information relating to FDA licensed products, FDA-approved indications, and aBLA and 505(b)(2) applications is obtained from public sources including the U.S. FDA website ( Information relating to litigations is given only for cases active from January 31, 2010 onward. Information relating to foreign biosimilar / biologics follow-on products approved in Australia, Canada, the E.U., Japan and South Korea is from public sources. Statistics graphics are compiled from information contained in the Venable BiologicsHQ database.


    The individuals who maintain this site work for Venable LLP. The information, comments and links posted on this site do not constitute legal advice. No attorney-client relationship has been or will be formed by any communication(s) to, from or with the site and/or the author. For legal advice, contact an attorney at Venable LLP or an attorney actively practicing in your jurisdiction. Do not send any confidential or privileged information to the author; neither Venable LLP nor the author will assume any liability or responsibility for it. If you send any information, documents or materials to the site, you give permission for the author to include them on or in the site. No information, documents or materials you send to the site will be considered confidential or privileged by Venable LLP or its lawyers. Also, no such information, documents or materials will be returned to you. All decisions relating to the content belong to the author.

    Subscribe for Future Updates