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Federal Circuit Finds Antibody Claims Invalid For Lack Of Enablement In View Of Amgen
10/11/2023On September 20, 2023, the Court of Appeals for the Federal Circuit affirmed a decision of the United States District Court for the District of Delaware in Case No. 1:17-cv-00509-TBD, Judge Timothy B. Dyk, finding claims of asserted U.S. Patent No. 7,033,590 (“the ’590 patent”) invalid for lack of enablement. Baxalta Inc. et al. v. Genentech Inc., __ F.3d __ (Fed. Cir. September 20, 2023). In its precedential decision, the CAFC held that the asserted claims are indistinguishable from those recently found invalid by the Supreme Court in Amgen Inc. v. Sanofi, 598 U.S. 594, 610–12 (2023).
Claim 1 of the ’590 patent covers all antibodies that (1) bind to blood clotting Factor IX/IXa and (2) increase the procoagulant activity of Factor IXa. The ’590 patent discloses the amino acid sequences of 11 such antibodies. All are monospecific, meaning that they bind to a single molecule. Using routine techniques, the inventors screened candidate antibodies to determine whether any antibodies bind to Factor IX/IXa and increase procoagulant activity, as claimed. The inventors discovered that only 1.6% of the thousands of screened antibodies increased the procoagulant activity of Factor IXa.
Appellant patentee sued defendant Genentech, alleging defendant’s Emicizumab antibody product infringes the ’590 patent. Emicizumab is a bispecific antibody that binds to two different molecules, Factor IXa and Factor X. Defendant moved for summary judgment of invalidity of claim 1 for lack of enablement. The district court granted defendant’s motion. Patentee appealed.
The CAFC first recited the law of enablement, which requires that a patent’s specification describe the invention and “the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains . . . to make and use the same.” 35 U.S.C. § 112(a). The CAFC further noted that, as the Supreme Court recently reaffirmed in Amgen Inc. v. Sanofi, the specification must describe how to make and use the full scope of the invention as defined by its claims.
On appeal, patentee argued that summary judgment of invalidity for lack of enablement was improper because, when viewing the evidence in the light most favorable to patentee, skilled artisans can obtain the full scope of claimed antibodies without undue experimentation. Specifically, patentee argued that skilled artisans can make and identify new claimed antibodies using the routine screening process disclosed in the ’590 patent and that such routine screening does not amount to undue experimentation. The CAFC disagreed.
The CAFC began by noting that, in Amgen, the Supreme Court held that claims to all antibodies that (1) bind to specific portions of a protein known as PCSK9 and (2) block PCSK9 from binding to certain low-density lipoproteins were not enabled by a specification that identified 26 exemplary antibodies—from amongst potentially millions of antibodies that would be within the scope of the claims. The Supreme Court further found that disclosure of a roadmap for performing research directed at finding additional examples amounted to little more than instructions to engage in trial-and-error exploration, and did not enable one to practice the full scope of the claims.
The CAFC then concluded that the case on appeal was materially indistinguishable from Amgen.
The CAFC explained that claim 1 of the ’590 patent covers all antibodies that (1) bind to Factor IX/IXa and (2) increase the procoagulant activity of Factor IXa. The CAFC further noted that similar to Amgen, there are millions of potential candidate antibodies within the scope of claim 1, but the written description discloses the amino acid sequences for only 11 antibodies with the two claimed functions. To obtain other undisclosed but claimed antibodies, the written description directs skilled artisans to (1) immunize mice with human Factor IX/IXa, (2) form hybridomas from the antibody-secreting spleen cells of those mice, (3) test those antibodies to determine whether they bind to Factor IX/IXa and (4) test those antibodies that bind to Factor IX/IXa to determine whether there is any increased procoagulant activity. The CAFC concluded that this procedure was just like the roadmap rejected by the Supreme Court in Amgen, and simply directs skilled artisans to engage in the same iterative, trial-and-error process that the inventors followed to discover the 11 antibodies they elected to disclose.
Moreover, reasoned the CAFC, it was undisputed that the ’590 patent does not disclose any common structural (or other) feature delineating the antibodies that will bind to Factor IX/IXa and increase procoagulant activity from those that will not. Nor does the patent describe why the 11 disclosed antibodies perform the claimed functions, or why the other screened antibodies do not.
The CAFC concluded that, under Amgen, such random trial-and-error discovery, without more, constitutes unreasonable experimentation that falls outside the bounds required by § 112(a). Finally, the CAFC noted that it did not interpret Amgen to have disturbed its prior enablement case law, including Wands and its factors for determining undue experimentation.
