The case law distinguishes between so-called “unpredictable arts” (e.g., the biological, chemical, and pharmaceutical arts) and “predictable arts” (e.g., electrical and mechanical arts) for purposes of Section 112 analysis for the very reason that one is considered “predictable” while the other, “unpredictable.”

The legal standards for written description and enablement are well-established. To meet the written description requirement, the specification must convey with reasonable clarity that as of the filing date the inventor was in possession of the claimed invention. Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 1560 (Fed. Cir. 1991); Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc) (specification must “clearly allow persons of ordinary skill in the art to recognize that [the inventor] invented what is claimed.”). The enablement requirement is met if the specification would allow a person of ordinary skill in the art (POSITA) to make and use the claimed invention without undue experimentation. Amgen, Inc. v. Sanofi, 598 U.S. 594, 611 (2023).

As a practical matter, the threshold for meeting the written description and enablement requirements is higher in the unpredictable arts than in the predictable arts. The courts have said as much.

Written Description in the Predictable Arts:  The U.S. Court of Appeals for the Federal Circuit has explained that in the predictable arts “a lower level of detail is required to satisfy the written description requirement than for unpredictable arts.” Hologic , Inc. v. Smith & Nephew, Inc., 884 F.3d 1357, 1361 (Fed. Cir. 2018) (citing to Ariad). The Federal Circuit recently confirmed this guideline: “Given the predictability of electro-mechanical inventions such as the one here … ‘a lower level of detail is required to satisfy the written description requirement than for the unpredictable arts.’” Rai Strategic Holdings, Inc. v. Philip Morris Products S.A., 92 F.4th 1085, 1090-91 (Fed. Cir. 2024) (citing Hologic).

Enablement in the Predictable Arts:  The amount of disclosure required for enablement is generally lower in the predictable arts than in the unpredictable arts. The disclosure of a single enabled embodiment can be sufficient in the predictable arts. Spectra-Physics, Inc. v. Coherent, Inc., 827 F.2d 1524, 1533 (Fed. Cir. 1987) (“[I]f an invention pertains to an art where the results are predictable, e.g., mechanical as opposed to chemical arts, a broad claim can be enabled by disclosure of a single embodiment”). In Epistar v. Intn’l Trade Com’n, the Federal Circuit held a claim for an LED with a transparent window layer was in the predictable arts and thus was adequately enabled by a single embodiment even if the claim “reads on another embodiment of the invention which is inadequately disclosed.” 566 F.3d 1321, 1336 (Fed. Cir. 2009) (citing Spectra-Physics).

Written Description/Enablement in the Unpredictable Arts:  In the unpredictable arts, the courts have taken a different approach because the modification of biochemical substances can have unpredictable results. The Supreme Court observed in Amgen that “[d]espite recent advances, aspects of antibody science remain unpredictable … [and] scientists understand that changing even one amino acid in the sequence can alter an antibody’s structure and function” in unpredictable ways. Amgen, 598 U.S. at 612-13. Accordingly, the courts have applied a higher standard for written description and enablement in the unpredictable arts. In Ariad, the Federal Circuit found that the disclosure of three types of molecules supporting the claimed substance for interfering with a gene transcription factor was insufficient to meet the written description requirement. Ariad, 598 F.3d at 1355-58. In Amgen, the Supreme Court held that a claim to antibodies for treating high cholesterol was not adequately enabled even though the specification disclosed multiple embodiments including 26 different antibodies identified by their amino acid sequences. Amgen, 598 U.S. at 612.

The Role of the ‘Genus’ Label in the Unpredictable Arts

The demanding requirement under Section 112 in the unpredictable arts is sometimes referred to as “full-scope” written description/enablement, meaning that the inventor must provide written description and enablement support for all embodiments encompassed by the claim. Amgen, 598 U.S. at 610 (“the specification must enable the full scope of the invention as defined by the claims”); Juno Therapeutics, Inc. v. Kite Pharma, Inc., 10 F.4th 1330, 1336 (Fed. Cir. 2021) (“written description [must] sufficiently demonstrate[] that the inventors possessed the full scope of the claimed invention”); Regents of the Univ. of Cal. v. Eli Lilly & Co., 119 F.3d 1559, 1568-69 (Fed. Cir. 1997) (the specification must provide written description support for the full scope of the chemical genus) (hereinafter, the “Eli Lilly” case).

Denominating a claim limitation a “genus” is often the trigger for requiring full-scope written description and enablement support. For example, the Amgen patent required full-scope enablement because it attempted to “claim … ‘the entire genus’ of antibodies” that binds and blocks the protein. Amgen, 598 U.S. at 602. The patent in Ariad required full-scope written description support because “[t]he claims are thus genus claims, encompassing the use of all substances that achieve the desired result of reducing the binding of the [transcription factor].” Ariad, 598 F.3d at 1341. The patent in Eli Lilly required full-scope written description support because it claimed a broad “genus of cDNAs.” Eli Lilly, 119 F.3d at 1569.

When a biochemical patent claims a genus, there is full-scope written description support only if the specification discloses (1) a representative number of species falling within the scope of the genus, or (2) structural features common to the members of the genus such that a POSITA can “visualize or recognize” members of the genus. Eli Lilly, 119 F.3d at 1568-69. As for enablement, the specification, as supplemented by the skills and knowledge of a POSITA, must enable a POSITA to make and use the full scope of species encompassed by the genus. Amgen, 598 U.S. at 610.

The Application of the Genus Label in In re Xencor/Ex parte Chamberlain

Application Ser. No. 60/803,690 claims “a method of treating a patient by administering an anti-C5 antibody.” Ex parte Chamberlain, App. No. 60/803,690 (PTAB Jan. 10, 2023) (“Board Dec.”), 2-3.

Jepson Claim 8 recites “a method of treating a patient by administering an anti-C5 antibody with an Fc domain, the improvement comprising said Fc domain comprising amino acid substitutions M428L/N434S … wherein said anti-C5 antibody with said amino acid substitutions has increased in vivo half-life.” Id.

Means-plus-function Claim 9 recites “[a] method of treating a patient by administering an anti-C5 antibody comprising: a) means for binding human C5 protein; and b) an Fc domain comprising amino acid substitutions M428L/N434S … wherein said anti-C5 antibody with said amino acid substitutions has increased in vivo half-life.” Board Dec., 3.

On appeal from an examiner’s rejection, the Board found that both claims are directed to a “broad genus of antibodies, treatment indications, and patients,” whereas the specification only disclosed one species of anti-C5 antibody (“5G 1.1”) and three treatment conditions (“autoimmune, inflammatory, or transplant indications”). Board Decision, 8. The Board thus found that the claims were not supported by an adequate written description under Section 112(a). Board Dec., 8, 29.

Following a notice of appeal, the Federal Circuit administratively remanded the case back to the PTO because “the novelty and complexity of issues presented in this case favor a more thorough evaluation and explanation than provided in the Board’s final written decision.” In re Xencor, App. No. 2023-2048, (Fed. Cir. Jan. 23, 2024), Slip Op. at 2.

The Director convened the Appeals Review Panel (ARP), which issued a decision agreeing with the Board that the claims were not supported by an adequate written description under Section 112. Ex parte Chamberlain, App. No. 16/803,690 (ARP-PTAB May 24, 2024) (“ARP Dec.”).

The case involves complicated questions on the written description requirements for Jepson claims and means-plus-function claims.

But the ARP decision ultimately turns on the phrase “treating a patient” in the preambles. The ARP provides some persuasive reasoning that the term is limiting for these claims. But the APR took the further step of assigning “treating a patient” a claim construction of “treating all patents and all diseases.” ARP Dec., 18. The ARP went on to explain this means the “genus of treating all patients and all diseases.” ARP Dec., 26 (emph. added).

The ARP’s construction of “treating a patient” in the preamble as the genus of treating all types of patients and all forms of disease was essentially fatal to the ability of the specification to provide adequate written description support. It is challenging to imagine any specification that could provide support for the treatment of all types of patients and all types of conditions.

That takes us back to the claim construction. Would a POSITA understand the plain and ordinary meaning of “treating a patient” to be the genus of treating all types of patients for all types of disease? See MPEP, Section 2111.01 (“words of the claim must be giving their plain meaning, unless such meaning is inconsistent with the specification”). Arguably not.

The ARP argues that the specification “does not define the term ‘treating’” and “merely mentions three classes of diseases/conditions.” ARP, 16. Accordingly, the specification thus “does not limit” these terms (id.) and thus they should encompass anything not precluded by the specification, the kind of reasoning that was rejected in In re Smith Int’l, Inc., 871 F.3d 1375, 1382-83 (Fed. Cir. 2017).

More fundamentally, the ARP never establishes that a POSITA would understand the plain and ordinary meaning of “treating a patient” as meaning the genus of all patients and all diseases.

An analogy can be drawn to a “method of reprogramming a processor” in the predictable arts. Assume that the preamble is limiting, as was found in Xencor. Most would agree that a POSITA would not consider “reprogramming a processor” to mean the genus of reprogramming all types of processors for all types of functions.

Perhaps the answer goes back to the different treatment of inventions in the unpredictable arts compared to the predictable arts.

It makes sense that inventions in the unpredictable arts are subjected to a higher standard for written description and enablement. But the ARP’s decision in Xencor largely turns on claim construction, and it is not clear at all that the claim construction exercise is, or should be, different in the unpredictable arts.

Closing Thoughts

In re Xencor is fully briefed for its second appeal (No. 24-1870) and is scheduled for argument on December 4, 2024. The rejection may be affirmed based on the alternative ground that the genus for “an anti-C5 antibody” does not find adequate written description support based on the single species disclosed in the specification. ARP, 27. Still, the case calls into question the issue of when a claim term should be construed to be a “genus” and whether that inquiry differs in the unpredictable arts compared to the predictable arts.

 

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