On February 24, 2026, the Court in Case No. 1:23-cv-10861 (D. Mass.) granted Amgen’s motions for summary judgment of invalidity of the claims of OssiFi-Mab’s (“OMAB”) U.S. Patent Nos. 8,877,196 (“the ’196 patent), 11,608,373 (“the ’373 patent”), and 11,807,681 (“the ’681 patent”) asserted against Amgen’s Evenity^® (romosozumab-aqqg).  Summary judgment was granted on the basis that the asserted claims lacked written description and were not enabled as required under 35 U.S.C. § 112.

Written Description of Genus of Antibodies for Use in the Claimed Methods

The Court first analyzed Amgen’s arguments that the genus of antibodies for use in the claimed methods was not adequately described.

Representative claim 8 of the ’196 patent recited a method of increasing bone density in a patient in need thereof using a composition comprising antibodies defined by the function of binding sclerostin, a naturally occurring protein involved in bone formation.  The claims were not limited to any particular type of antibodies, and included, inter alia, “naturally occurring”, “non-naturally occurring”, “polyclonal” and “monoclonal” antibodies.  The Court determined that the specification lacked written description because it failed to disclose a representative number of species falling within the genus and did not describe common structural features of the genus so that one of skill could visualize or recognize the members of the genus.  The specification disclosed, at most, 31 anti-sclerostin antibodies, many of which were rat and murine antibodies, that could not be used in a human therapeutic.  None of the disclosed antibodies, either in the specification or in the prior art, had any disclosed sequence information, and it was unknown whether the disclosed antibodies inhibit sclerostin’s function.  There were no bispecific or humanized antibodies disclosed, despite the claims covering such antibodies.  The antibodies that were described were all of a similar type and did not represent all the types encompassed by the claims.  The Court held that simply describing how to make and test the claimed antibodies is insufficient to meet the written description requirement.

Representative claims 15 of the ’373 patent and 29 of the ’681 patent recited “serially administering” an antiresorptive drug to a human subject with low bone mass during treatment with “a sclerostin recognizing antibody.”  The parties agreed that the preambular phrase “being treated with a sclerostin-recognizing antibody” is limiting.  The Court disagreed with OMAB’s argument that the written description requirement did not apply because administering an antibody was not a step in the claimed methods and instead found that a limiting preamble is subject to the written description requirement.  The Court found that the ’373 and ’681 patent claims failed to meet the written description requirement for the same reasons as for the ’196 claims.

Enablement of Genus of Antibodies for Use in the Claimed Methods

The Court analyzed the Wands factors and concluded that, similar to its determination for written description, the claims involve a broad, functionally defined genus of antibodies (the actual number was disputed but according to OMAB’s expert, could include 35,000 species) that would need to be made and screened to determine which ones performed the claimed inventions, which “is the definition of trial and error” and, therefore, requires undue experimentation.  Citing Amgen v. Sanofi (598 U.S. 594, 613 (2023)), the Court held that “the more a party claims, the broader the monopoly it demands, the more it must enable.”  For the ’373 and ’681 patents, similar to the Court’s written description analysis, it determined that the preamble was limiting and the enablement requirement applied to those claims.

Written Description of Claimed Methods

For the ’196 patent, the Court found the claims lacked adequate written description because the inventor was not in possession of the claimed methods, which required sequential administration of an “effective amount” of a sclerostin antagonist and an antiresorptive drug to systemically increase bone density, as of the priority date.  It found that while “[t]he asserted claims in the ’196 patent cover methods of treatment involving, at least, an enormous number of possible combinations of numerous antibodies with numerous species of antiresorptive agents,” the specification “does not include any working examples of the claimed methods.”  Moreover, the inventor testified that as of the priority date, she could not have named any antibody that would be effective in the claimed methods.  OMAB’s expert pointed to information in the specification about individual components of the methods, but the Court did not find this alone was adequate to describe the “expansive nature” of the method claims.

While the ’373 and ’681 patents did not claim efficacy, the Court still concluded that Amgen had met its burden for the same “non-efficacy-related” reasons as the ’196 patent.

Obviousness and Written Description of Claimed Methods Using Vitamin D

As to obviousness, the Court disagreed with Amgen’s arguments that the claims must be construed to include concurrent administration of the anti-sclerostin antibody and antiresorptive drug (e.g., Vitamin D), which rendered them obvious, because this was contrary to the Court’s claim construction which allows for “serial or sequential” administration.

Relying on the same analysis from its decision on written description, the Court again found the claims were inadequately described, and that OMAB’s other arguments did not compel a different outcome.

Amgen reported $1.6 billion in U.S. sales for Evenity^® in 2025.

For more information on this and other biologic drug patent disputes, please visit BiologicsHQ.com.

 

_____________________________________________________

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