In March 2008, the U.S. PTO issued newly revised written description guidelines for use in the examination of primarily biotechnology patent applications to ensure that they comply with the requirements of 35 U.S.C. § 112. The written description requirement ensures a quid pro quo in which the public is given meaningful disclosure in exchange for the patentee being granted a limited monopoly for the invention.
A proper written description in a patent application demonstrates that the applicant was in possession of the claimed invention at the time of filing. Possession of the invention is shown by describing the invention with adequate specificity such as by words, structures, figures, diagrams, and formulas. The sufficiency of the written description of a representative number of species determines the scope of the allowable claims.
These new written description guidelines supersede the previous set of guidelines issued by the U.S. PTO in 1999. Those guidelines were published to address the 1997 Federal Circuit decision of Regents of the University of California v. Eli Lilly, which addressed written description requirements particularly relevant to biotechnology inventions, specifically those that claimed nucleic acid sequences. The Federal Circuit held that the description of a claimed genus of cDNAs may be achieved by reciting a representative number of specific cDNAs, or the structural features common to the genus members.
The newly issued written description guidelines were promulgated in response to developments in case law since the Lilly decision. For example, the 2005 Capon v. Eshhar case permitted reliance upon specific sequences that were known in the art, rather than requiring them to be recited in the specification. This case developed a series of factors to be considered for a sufficient description that are similar to the enablement factors from the Federal Circuit’s 1988 in re Wands decision.
Claiming Biotech Inventions
The written description guidelines state that if a claim encompasses a single embodiment or species that has not actually been reduced to practice, the examiner should determine whether the invention has been set forth or described in terms of distinguishing characteristics that are identified and sufficiently detailed to show that the applicant was in possession of the claimed invention.
Factors to be considered in determining whether the applicant is in possession of the invention include the level of skill and knowledge in the art, partial structure, physical and/or chemical properties, functional characteristics alone or coupled with a known or disclosed correlation between structure and function, and the method of making the claimed invention.
Many of the examples provided in the guidelines are similar to those set forth in the 1999 guidelines, while others make substantial distinctions. The new written description guidelines for antibodies to a single protein (listed as Example 13) present a claim that is identical to a claim in Example 16 of the 1999 guidelines.
Claim 1, an isolated antibody capable of binding to antigen X reads as follows: The specification of the hypothetical application containing this claim discloses that antigen X is well-characterized in that the purification procedure used to isolate antigen X, some of its biochemical characteristics, and its amino acid sequence are disclosed. The specification also discusses antibodies that specifically bind to antigen X, which can be used in immunoassays to detect an associated disease.
Differences and Similarities
The specification, however, does not contain either a working example or a prophetic example of an antibody that binds to antigen X. Regardless, both the 1999 and the 2008 guidelines recognized that the level of skill and knowledge in the art of antibodies was such that the production of antibodies against a well-characterized antigen was routine. Both the 1999 and 2008 guidelines, therefore, conclude that the specification satisfies the written description requirement of § 112, first paragraph, with respect to the full scope of claim 1.
There are some types of claims, however, that should be drafted differently in view of significant changes in the guidelines. For example, both Example 7 of the 1999 guidelines and Example 4 of the 2008 guidelines discuss a claim to “an isolated DNA comprising SEQ ID NO: 16.” The hypothetical specification similarly discloses that SEQ ID NO: 16 is a partial cDNA expressed sequence tag, the cDNA fragment specifically hybridizes with the complement of the coding sequence in yeast DNA, and is useful in identifying yeast infections.
The 1999 guidelines concluded this claim does not fulfill the written-description requirement because the term “comprising” is open-ended, and the specification discloses only a single common structural feature shared by members of the claimed genus, i.e., SEQ ID NO: 16. The 1999 guidelines conclude this partial sequence does not provide an adequate description of the claimed genus.
In contrast, the 2008 guidelines conclude the claim does meet the written description guidelines because the scope of the genus is defined by the presence of the structure disclosed as SEQ ID NO: 16, and it is within the skill of the art to add any desired DNA to either end of SEQ ID NO: 16. Note that the PTO warns that the scope of this claim may not survive the requirements of utility or enablement by the specification.
Protein or Nucleic Acid Sequences
In claims that are directed toward protein or nucleic acid sequences that contain a specified percent identity with another sequence, the U.S. PTO has also apparently relaxed its written description guidelines. Example 11 of the 2008 guidelines contains the following exemplary claims:
Claim 1: An isolated nucleic acid that encodes a polypeptide with at least 85% amino acid sequence identity to SEQ ID NO: 2.
Claim 2: An isolated nucleic acid that encodes a polypeptide with at least 85% amino acid sequence identity to SEQ ID NO: 2; wherein the polypeptide has activity X.
In Example 11 of the 2008 guidelines, the PTO has now determined that even where the hypothetical specification discloses only a single species encoding SEQ ID NO: 2, claim 1 meets the written description requirement because a skilled artisan could use a computer to identify all the nucleic acids that encode a polypeptide with at least 85% identity to SEQ ID NO: 2.
The PTO now asserts that once functional language is inserted into the claim, such as that added in claim 2, absent adequate support in the specification to teach which amino acid residues can be altered without a concurrent loss of activity, the claim is then limited to a specific species without adequate guidance to show which species are within the subset and which are excluded from the subset. Claim 1 is supported by the written description, and claim 2 is not.
While the 2008 guidelines appear to be loosening the requirement for written descriptions, the PTO has made it clear that although these claims exemplified may or may not comply with the written description requirement, they must also pass the enablement requirements of 35 U.S.C. § 112. Additionally, the claims must also comply with the utility requirement of § 101 as well as novelty and nonobvious requirements of § 102 and 103.
One practice tip that remains consistent is that a patent applicant should disclose all available relevant information. This includes known variants, positions of known mutations versus activity, sequence alignments, and known consensus sequences in those alignments to demonstrate the applicant possesses enough species of the claimed invention to satisfy not only the written description requirement, but also the enablement requirement. In this way, a patent applicant will be in the best position to support the issuance of the broadest possible claims.
Written Description Training Materials
New written description guidelines can be reviewed at www.uspto.gov/web/menu/written.pdf. The guidelines provide a series of 17 examples, 14 of which are specifically directed toward claiming biotechnology inventions:
expressed sequence tags, or ESTs
partial protein structures
DNA hybridization claims
allelic variants of a specific gene sequence
a product claimed by its function, such as a protein that catalyzes a specific biochemical reaction
a nucleic acid or protein sequence that has a percent identity with another sequence
antibodies to a single protein
antibodies to a genus of proteins
a genus with widely varying species, such as homologous genes from different species that differ in their sequence
process claims where novelty resides in the process steps, such as introducing a nucleic acid into an organelle to treat a specific disease or condition
methods of using compounds claimed by functional limitations, methods of identifying compounds and compounds identified by such methods