Describing Use of a Genus: Teva V. Lilly Clarifies § 112 For Antibody Method Claims

Patent law requires more than showing that an invention is new and nonobvious. Under 35 U.S.C. § 112, a patent must also describe the invention in enough detail to show that the inventors possessed what they claimed and to teach skilled readers how to make and use it without undue experimentation. These requirements are known as written description and enablement. In biotechnology cases, these requirements can be difficult to satisfy when a patent claims a chemical genus. A genus claim covers a group of structurally or functionally related chemical substances. Genus claims tend to be difficult to obtain for related antibodies. The Supreme Court’s decision in Amgen Inc. v. Sanofi[1] confirmed that broad claims to antibodies themselves can fail enablement when the patent does not teach skilled readers how to make and use the full scope of the claimed antibodies. The Federal Circuit’s recent decision in Teva Pharmaceuticals International GmbH v. Eli Lilly and Company[2] addresses how § 112 applies when the patent does not claim the antibody genus itself, but instead claims a method of using that genus to treat a specific condition. In Teva, the Federal Circuit concluded Eli Lilly and Company (“Lilly”) failed in its argument that a reasonable jury could not have found that Teva’s headache treatment patents satisfied the requirements of written description and enablement.  The Federal Circuit thus reversed the district court which had agreed with Lilly and rejected the jury’s verdict.     

The patents at issue involve methods of treating headache using humanized anti-CGRP antagonist antibodies. CGRP is a protein associated with headache and migraine biology. When CGRP binds to receptors on certain cells, it can cause those cells to expand and increase blood flow through blood vessels, a phenomenon associated with headache. Anti-CGRP antagonist antibodies bind to CGRP and inhibit that activity. The asserted claims were not directed to the antibodies as compositions. Instead, they were directed to methods of using those antibodies to treat headache.

The representative claim recites:

“A method for reducing incidence of or treating headache in a human, comprising administering to the human an effective amount of an anti-CGRP antagonist antibody, wherein said anti-CGRP antagonist antibody is a … humanized monoclonal antibody.”

Teva Pharmaceuticals International GmbH (“Teva”) sued Eli Lilly and Company (“Lilly”), alleging that Lilly’s Emgality® product infringed Teva’s headache patents. A jury found that Lilly willfully infringed and failed to prove the asserted claims invalid for lack of written description or enablement. After trial, however, the district court granted judgment as a matter of law, which means the judge set aside the jury’s validity finding and concluded that the claims were invalid under § 112. On appeal, the U.S. Court of Appeals for the Federal Circuit reversed the district court’s ruling and reinstated the jury’s verdict.

Turning first to written description, Lilly argued that Teva’s patents failed this requirement because the specification disclosed only one humanized anti-CGRP antagonist antibody. For genus claims, satisfying the written description requirement often is accomplished by disclosure of either a representative number of species within the genus or structural features common to the genus. According to Lilly, the disclosure of only one humanized anti-CGRP antagonist antibody was not enough to support claims covering the broader genus of humanized anti-CGRP antagonist antibodies.

The Federal Circuit disagreed with the district court’s resolution of that issue as a matter of law. The court emphasized that the claimed invention was not the antibody genus itself. Rather, the invention was the use of anti-CGRP antagonist antibodies to treat headaches. This distinction changed the written description analysis.  The court explained that this case involved a claim using a known genus as part of a different invention.  Anti-CGRP antagonist antibodies and methods of making such antibodies were known in the art.  Humanization of antibodies was also a well-established and routine process by the priority date.  

Lilly’s own earlier statements in inter partes review proceedings alleging obviousness supported those points.  Lilly tried to distinguish written description, focusing on the fact that humanized anti-CGRP antagonist antibodies themselves were not well known in the prior art and that the specification disclosed only one humanized example.  However, the Federal Circuit found that focus unpersuasive.  The specification disclosed murine anti-CGRP antagonist antibodies and disclosed prior-art methods for humanizing antibodies.  The court explained that the jury could have viewed the disclosed mouse antibodies as already known examples that could be converted into humanized antibodies through a routine and disclosed humanization process. However, this does not mean that one disclosed species will always support use of a broad genus.    In this case, the antibody class was known, methods of making antibodies were known, humanization was routine, and the specification supported the conclusion that humanized anti-CGRP antagonist antibodies would treat headache.  In that context, the Federal Circuit held that a reasonable jury could find adequate written description.

The Federal Circuit also rejected Lilly’s argument that the difference between claiming antibodies and claiming a method of using antibodies was merely a semantic distinction.  The court distinguished cases such as University of Rochester v. G.D. Searle[3] and Ariad Pharmaceuticals v. Eli Lilly[4], where method claims failed because the specifications did not adequately disclose usable compounds or molecules for performing the claimed methods.  In Teva, by contrast, the relevant antibodies were not unknown black boxes.  The specification disclosed examples, the art already knew anti-CGRP antagonist antibodies, and humanization techniques were routine.  The claimed method also did something different from the function that defined the antibodies.  The claims were not simply directed to using antibodies that antagonize CGRP to antagonize CGRP, but they were directed to treating headache using such antibodies. The court did not require Teva to disclose every antibody. It focused on the claimed use of treating headache. Because the antibody type was known and the patent explained that this type could be used for headache treatment, the jury could find written description was satisfied.

Turning next to enablement, Lilly argued that the claims failed this requirement because identifying all antibodies within the genus would require screening and testing a very large number of candidates.  The Federal Circuit acknowledged that this argument might be stronger if the claims were directed to the antibodies themselves.  That would make the case more similar to Amgen and Baxalta[5], where the claims covered broad antibody genera.  However, Teva’s claims were different because they were limited to a specific method of treatment. They did not claim humanized anti-CGRP antagonist antibodies themselves.  Instead, they claim only the use of such antibodies for the different and limited purpose of treating headache.  As such, Teva did not have to identify every possible anti-CGRP antagonist antibody for every purpose.  The relevant question was which humanized anti-CGRP antagonist antibodies treat headache.  On the jury-supported record, that work had already been completed because the specification taught that all such antibodies worked for that purpose. The Federal Circuit captured this point with a memorable phrase that finding or making all such antibodies would be “more akin to extra credit than a necessary research assignment left to others to complete.” That was the key enablement point. Enablement must match the scope of the claim.  Since the claim was directed to treating headache, not to owning the antibody genus for all purposes, the patent did not necessarily need to teach how to make every possible antibody in the genus as if the antibodies themselves were the invention.

Teva v. Lilly does not eliminate § 112 risk for broad biotechnology claims.  Broad antibody composition claims remain vulnerable when they claim a large genus without teaching skilled artisans how to make and use the full scope. However, this decision confirms that method-of-treatment claims may be treated differently.  When the claimed invention is a specific therapeutic use of a known genus, and the specification supports that members of the genus work for that use, written description and enablement may be satisfied even without disclosing many humanized species or amino acid sequences. The decision also highlights a practical relationship between obviousness and § 112.  Lilly’s earlier arguments that anti-CGRP antagonist antibodies and humanization methods were well known helped support Teva’s position that the claims were adequately described and enabled.  A party arguing that a technology was routine for obviousness purposes may face difficulty later arguing that the same technology was too unpredictable or insufficiently described for § 112 purposes.

Our takeaway is that method-of-use claims should be drafted and analyzed based on the specific claimed use. When the claimed invention uses a known genus, the specification should explain why that genus works for the claimed use, not just identify the genus. For § 112 challenges, the focus should be on the actual claimed invention. If the claim is directed to using a known genus for a specific purpose, it may not be enough to argue only that the genus itself is broad.

Teva v. Lilly does not change the rule from Amgen. When a patent claims a genus itself, the patentee must support the full scope of that genus. However, when the patent claims a specific method of using a known genus, the analysis may focus on whether the specification supports that claimed use.  In Teva, the Federal Circuit found that a reasonable jury could view the antibody genus as a tool used in the claimed treatment method, not as the invention itself.