Patent Antibody Case Law Continues To Mature

• Published date: 08 March 2022
• Subject Matter: Intellectual Property, Food, Drugs, Healthcare, Life Sciences, Patent, Biotechnology & Nanotechnology
• Law Firm: Arnold & Porter
• Author: Mr Daniel L. Reisner

Co-authored with James Evans, Regeneron Pharmaceuticals, Inc.

Explosive growth of antibody technology and therapeutics over the past three decades has driven development of antibody-centric patent case law across several fronts. During this time, the Federal Circuit has decided over 40 cases involving antibodies, spurred by the approval of over 100 therapeutic antibodies.

Over the last decade, in particular, several cases have elucidated the Federal Circuit's approach to construing antibody-related terms in patent claims (claim construction) and the written description and enablement requirements under 35 U.S.C. ' 112 for antibody patents. Both claim construction and 35 U.S.C. ' 112 requirements are often dispositive in determining infringement and patent validity. Specifically, section 112 sets out, among other things, two requirements for the amount of disclosure an applicant must include in their patent: (1) a description of the subject matter of the invention showing that the inventor had possession of the claimed invention (written description); and (2) a disclosure that enables a person of ordinary skill in the art to make and use the invention without undue experimentation (enablement). This article addresses recent antibody decisions concerning claim construction, written description and enablement.

• Claim Construction
• Written Description
• Enablement
• Conclusion

Claim Construction

In Biogen v. GlaxoSmithKline LLC, 713 F.3d 1090 (Fed. Cir. 2013), the term "monoclonal antibody" was construed for Biogen's U.S. Patent No. 7,682,612. The parties' proposed constructions are below; the court's construction is in red.

Key to the construction was intrinsic evidence from the patent prosecution. The examiner rejected claims as not enabled that were drawn to the broad genus of anti-CD20 antibodies. The court observed that the examiner found the specification enabled the application of RITUXAN', RITUXIMAB' and 2B8-MX-DTPA in the treatment of hematologic malignancies, which were in the specification, but did not enable other anti-CD20 antibodies that have different specificity or affinity for the specific epitope. Id. at 1095-1096. The court noted the applicant's response that the specification was enabling for anti-CD20 antibodies with similar affinity and specificity as Rituxan' and that the applicant did not dispute the examiner's reference to a "specific epitope." Id. at 1096.

The court found that GSK's Arzerra' (ofatumumab) product is notably different from Rituxan' (rituximab) in several respects, including that Arzerra' binds to a different epitope and has a much greater affinity for the CD20 antigen. The Federal Circuit affirmed the district court's holding that the applicants limited the claims to antibodies similar to Rituxan' during prosecution. Id. at 1097.

In Immunex Corp. v. Sanofi-Aventis U.S. LLC, 977 F.3d 1212 (Fed. Cir. 2020), the term "human antibody" was construed for Immunex's U.S. Patent No. 8,679,487 on appeal from the Patent Trial and Appeal Board (PTAB). The parties' proposed constructions are below; the court's construction is in red.

Here, again, intrinsic evidence was determinative. Immunex cited a prior district court construction limiting the term "human antibody" in the patent to fully human antibodies and to extrinsic evidence such as experts' testimony, product catalogs, and some journal articles to argue "human antibody" had an established limited meaning in the art. The court, however, did not find the arguments persuasive in light of Sanofi's intrinsic evidence. Sanofi relied on statements in the patent specification, including: "The antibodies may be partially human, or preferably completely human" and "Antibodies of the invention include, but are not limited to, partial human (preferably fully human) monoclonal antibodies ...." Id. at 1218-1219.

The Federal Circuit determined that the PTAB was not obligated to justify arriving at a different construction than a district court did in a parallel infringement proceeding. Id. at 1223. The court held that, based on the intrinsic evidence, the PTAB was correct to give little weight to the extrinsic evidence and to construe the claim term "human antibody" as including...