Recently, in Yeda Research and Development v Abbott GMBH & Co. KG, the U.S. Court of Appeals for the Federal Circuit (CAFC) weighed in on the issue of inherent disclosure as a means for satisfying the written description requirement under 35 USC 112. The patent at issue in this case is U.S. Patent No. 5,344,915, which claims a protein termed TBP-II. TBP-II plays a role in various immunological diseases.

The ‘915 patent had a filing date of May 4, 1990, but claimed priority to two German patent applications filed May 9, 1989, and July 5, 1989. During prior litigation at the PTAB and district court, it was stipulated by the parties that a prior art reference (Engelmann, having a prior art date of January 1990) provided an anticipating disclosure if the priority date of at least one of the prior applications was not recognized. The written description issue centered on the adequate support from the claimed amino terminal sequence of TBP-II claimed in the ‘915 patent.

Claim 1 of the ‘915 patent reads:

A purified and isolated TNFα-binding protein which has a molecular weight of about 42,000 daltons and has at the N terminus the amino acid sequence:

Xaa Thr Pro Tyr Ala Pro Glu Pro Gly Ser Thr Cys Arg Leu Arg Glu, where Xaa is hydrogen, a phenylalanine residue (Phe), or the amino acid sequences Ala Phe, Val Ala Phe, Gln Val Ala Phe, Ala Gln Val Ala Phe, Pro Ala Gln Val Ala Phe or Leu Pro Ala Gln Val Ala Phe.

Disclosure of the Priority Documents

Both of the priority documents disclosed partial amino acid sequences of the amino terminal fragment. The ‘072 application disclosed a 15 amino acid sequence, with eight of the amino acids residues being identified as disclosed in the ‘915 patent, six of the amino acids residues being defined as unknown (with likely assignments given to five residues) and the Xaa position being defined with a generic structure. The ‘089 application disclosed the first 13 amino acids claimed in the ‘915 patent but gave no disclosure of the final three amino acids.

Therefore, the priority documents did not disclose the entire amino terminal sequence of TBP-II as claimed in the ‘915 patent and were limited to partial amino terminal sequences. Both priority documents disclosed methods for obtaining TBP-II and certain properties of TBP-II (such as molecular weight, biological activity and the like). The parties also stipulated that the only protein containing the amino terminal sequence set forth in the earliest priority document (‘072) was TBP-II.

CAFC Analysis

The CAFC explained the legal standards for written description support under section 112. The court cited Kennecott Corp. (Fed. Cir 1987) for the proposition that in order for the claims of a later filed patent to benefit from the filing date of a prior application, the “claimed invention must be disclosed” by the prior application. Regarding the sufficiency of the disclosure required, the court cited Ariad Pharmaceuticals (Fed. Cir. 2010), stating the “invention must be disclosed in a way that clearly allows a person of ordinary skill to recognize that the inventor invented what is claimed and possessed the claimed subject matter at the date of filing.” Interestingly, the CAFC did not cite its prior case law regarding the stringency with which a disclosure must be made to support inherent anticipation under section 102. For inherent anticipation, the standard for a sufficient disclosure is the inherent feature “is necessarily present in the prior art document” and mere probability or possibility of the existence of the inherent feature is not enough.

Yeda argued that the correct standard for the sufficiency of written description requires a showing that at the time of filing of the priority document, one of ordinary skill in the art would have understood the partial amino acid sequence disclosed included the amino acids identified in the later filed application (a concept which has been expressly rejected under the inherent anticipation case law). The CAFC dismissed this argument, stating that “when a specification describes an invention that has certain undisclosed yet inherent properties, that specification serves as adequate written description to support a subsequent patent application that explicitly recites the invention’s inherent properties.” The CAFC appeared to place great weight on the fact that the disclosure of the priority documents was sufficient to specifically identify TBP-II. In other words, since the priority documents uniquely identified a single protein (through partial sequence, functional characterization and physical characterization), any missing elements of the protein could be said to be inherently disclosed by the priority documents. Restated, one could say the disclosure of the more complete amino terminal sequence of TBP-II is a “deliberate or necessary consequence” of the priority documents disclosure.

The CAFC distinguished two prior decisions cited by Yeda (Hyatt v. Boone and In re Wallach) on the basis that neither of these cases described a case where an earlier application described “the exact invention claimed by the later patent.” Interestingly, In re Wallach claimed a nucleic acid encoding the full-length TBP-II protein based on the disclosure of a partial amino acid sequence and description of the physical characteristics of the protein (part of a series of cases filed by Yeda covering the technology at issue in this case). The applicant argued that since the full amino acid sequence of the protein was an inherent feature of the protein, the claims to the nucleic acid were adequately supported. The CACF disagreed with this proposition in 2004 stating that the disclosure of a partial amino acid sequence did not unambiguously determine the nature of the full-length nucleic acid encoding the protein (Yeda ultimately obtained claims for a nucleic acid sequence to the partial amino acids it disclosed).

Conclusions

While this case may be viewed as a liberal application of the inherency standard, given the disclosure of the ‘089 application explicitly disclosed 13 of the 16 amino acids claimed in the ‘915 patent and the fact that the priority documents uniquely identified the protein of interest, the decision of the court may be easier to understand. This decision is likely to be limited to the facts described in this case, namely applying only when the later claimed application can be shown to claim the exact invention disclosed in the priority document.

In any event, this case provides additional arguments for a lenient application of inherent disclosure and broadens the scope for written description support from a priority document. However, the conclusion in In re Wallach and this case appear to be slightly at odds with one another. Is there a limit to the amount of disclosure that can be said to be inherently disclosed by a priority document? Could Abbott have obtained a claim for a full length nucleic acid sequence encoding TBP-II based on the holding of this case? Finally, do the claims held allowable in this case survive a section 101 analysis? This issue was not raised by the parties.