Practitioners Be Wary: The Dangers of Functional Descriptions in Biotech Inventions
Published By Andrews Entertainment Industry Litigation Reporter August 19, 2003

Jeffery M. Duncan, Helen A. Odar, C. Noel Kaman

Darwin once said, '[i]n science, the credit goes to the man who convinces the world, not the man to whom the idea first occurs.' But Darwin wasn't talking about the world of patents where credit, in the form of a U.S. patent, goes to the man who describes the invention in sufficient detail, not to the man who merely describes a wish or plan for achieving it. The United States Patent Act specifically requires: '[t]he specification shall contain a written description of the invention . . . .' 1

This requirement, known as the 'written description' requirement, is intended to ensure that the inventor was actually in possession of the invention at the time the application was filed. This can be crucial for biotech patent applications, many of which are filed early in the discovery process when inventions can be especially difficult to describe. Often, it is easier to describe a biologically active compound, a genetic sequence or other biological material by what it does, rather than by what it is. Thus, the issue has frequently arisen as to whether such functional descriptions satisfy the written description requirement. A review of the recent case law on written description is instructive.

I.   The Written Description Requirement: A Sword for Invalidating Biotechnology Patents

In the last six years, several patents to biotech inventions have been found not to satisfy the written description requirement. Patents that were otherwise valid have been struck down because the description of the invention, often by functional terms, was found wanting.

One difficulty for biotech patent practitioners is that there are no bright line rules prescribing what is or is not an adequate written description. Instead, as the Court of Appeals for the Federal Circuit has repeatedly stated, the satisfac-tion of the written description requirement is a fact-specific inquiry, decided on a case-by-case basis. Thus, to obtain guidance from the published written description cases, one must focus on the specific facts involved. In particular, the following facts must be noted in these cases:

  1. the specific invention at issue;
  2. the aspects of that invention that were disclosed and those that were not;
  3. how the disclosed aspects were described; and
  4. whether the description was found to be sufficient.

Analyzing these written description cases with this framework provides the prudent practitioner with some guidance on how to ensure the description of the invention in the patent application will meet this important requirement.

A.   The Written Description Sword Invalidated the Claims in Regents of the University of California v. Eli Lilly & Company

In 1997, the Federal Circuit sent a strong message to the biotech community as it invalidated an important biotechnology patent for failure to satisfy the written description requirement. The Federal Circuit affirmed the district court's finding that the University of California's patent (U.S. Patent 4,652,525, hereafter 'the '525 patent') was invalid, Regents of the University of California v. Eli Lilly & Co.2

The '525 patent, filed twenty years earlier, in 1977, was based on the determination of the proinsulin and preproinsulin cDNA sequences found in rats.3 Nevertheless, the claim at issue in the '525 patent, claim 5, defines a microorganism containing cDNA encoding human insulin.4 The specification of the '525 patent described cDNA encoding rat insulin, including the sequence of the rat cDNA and the method used to isolate it. In addition, the '525 patent disclosed, in a 'constructive' example, a method of obtaining a cDNA encoding human insulin.5 However, the specification did not disclose a working example of a cDNA encoding human insulin or its sequence.

The Court found this disclosure to be inadequate and characterized the description as providing 'only a general method for obtaining the human cDNA (it incorporates by reference the method used to obtain the rat cDNA) along with the amino acid sequences of human insulin . . . .'6 The Court stated that the disclosure was not a written description of cDNA encoding human insulin because '[t]he name cDNA is not itself a written description of that DNA; it conveys no distinguishing information concerning its identity. While the example provides a process for obtaining human insulin-encoding cDNA, there is no further information in the patent pertaining to that cDNA's relevant structural or physical characteristics. . .'7 The Court held that due to the lack of structural information, i.e. sequence information about the cDNA, the claim element was not sufficiently described because '[a] definition by function . . . does not suffice to define the genus . . .'8 Rather, some structure that correlates to the function, thereby setting the members of the genus apart from other species, should have been described.

As can be seen in the quotes above, although the Federal Circuit was not satisfied with the functional description in this case, it did provide some guidance as to what does constitute an adequate written description of a genetic material invention. Specifically, the Court stated that functional descriptions correlated to known or disclosed structures could provide an adequate written description. In addition, the Court stated that the methods it had discussed to satisfy the written description requirement were not necessarily exhaustive. In other words, the Court left the door open for other methods to satisfy this requirement.

II.   The USPTO Written Description Guidelines: A Practitioner's Shield

Largely in response to the Eli Lilly case, the United States Patent and Trademark Office, USPTO, promulgated extensive guidelines to help its examiners determine whether the written description requirement had been met, namely the Guidelines for the Examination of Patent Applications Under the 35 U.S.C. § 112, 1, 'Written Description' Requirement ('the Guidelines').9 The Guidelines were largely derived from the analysis of cases discussing the written description requirement, and the analysis of the particular facts in each case, relevant to that analysis. A draft of the Guidelines was published in 1999 and received voluminous comments from the patent bar. The final version of the Guidelines was published and made effective on January 5, 2001.

Although these Guidelines are not wholly binding on the judiciary, they may be given judicial notice to the extent they do not conflict with the statute.10 Moreover, the Guidelines have been favorably discussed by the Federal Circuit and have even been adopted in part.11

The Guidelines provide a valuable summary of the law on the written description requirement. The Guidelines also set out the procedure an examiner should use in evaluating each case to determine if it has met the written description requirement. As a first step, the examiner is to 'determine what the claim as a whole covers.'12 Next, the examiner is to 'review the entire application to understand how applicant provides support for the claimed invention including each element and/or step.'13 Finally, the examiner is to 'determine whether there is sufficient written description to inform a skilled artisan that applicant was in possession of the claimed invention as a whole at the time the application was filed.'14

In situations where the complete structure of an invention is not provided, the examiners are advised to consider factors such as the 'partial structure, physical and/or chemical properties, functional characteristics alone or coupled with a known or disclosed correlation between structure and function . . . .'15 The examiners are instructed that '[d]isclosure of any combination of such identifying characteristics that distinguish the claimed invention from other materials and would lead one of skill in the art to the conclusion that the applicant was in possession of the claimed species is sufficient.'16 With regard to biotech inventions, deposit of a biological material is specifically sanctioned as a way to show actual reduction to practice and possession of that biological material.17

III.   The Pen is Mightier than the Sword: Functional Descriptions Combined with Additional Information Can be Sufficient

Since the promulgation of the Guidelines, several cases have dealt with the issue of whether a functional description was sufficient to meet the written description requirement. Three are particularly instructive.

A.   In Enzo II, the Written Description Sword was Blocked

In 2002, the Federal Circuit addressed a patent with a functional description of the invention, in a series of cases titled, Enzo Biochem, Inc. v. Gen-Probe Inc.18 These cases involved U.S. Patent 4,900,659 ('the '659 patent'), which was directed to nucleic acid probes useful in diagnosing gonorrhea.19 The specification did not give sequences for these probes, but only referred to what they were able to do, i.e. hybridize to the DNA of Neiserria gonorrhea over Neiserria meningitides. The specification did reference a deposit of strains of host cells capable of producing these probes with the American Tissue Culture Collection (ATCC),20 a practice sanctioned by the U.S.P.T.O. since the 1980's.21

At the district court level, the judge granted a motion for summary judgment that, in spite of the deposit of the cell lines, the claims were invalid for failing the written description requirement.22 In its first decision in April of 2002 (Enzo I),23 the Federal Circuit affirmed, holding that, even with the deposit of the cell lines, the patentee's recitation of what the probes did, instead of what they were, was insufficient as a matter of law.

Naturally, this decision in Enzo I sent shockwaves throughout the biotech community. Biotech companies that had been relying on the deposit of biological materials to satisfy the written description for several years were concerned that their patents could be invalidated as well.

The shockwaves ended in July of 2002 when the Federal Circuit reversed itself on rehearing (Enzo II). In the opinion, the Federal Circuit referred back to the Eli Lilly case where it had considered claims to genetic material that had only been defined by function, and found that the functional description alone was insufficient to satisfy the written description requirement.24 However, the Federal Circuit clearly stated that not all functional descriptions of genetic material would fail to meet the written description requirement, particularly not when functional characteristics are coupled with a known or disclosed correlation between function and structure.25

In perhaps the most important aspect of this case for biotech companies, the Federal Circuit held that 'reference in the specification to a deposit in a public depository, which makes its contents accessible to the public when it is not otherwise available in written form, constitutes an adequate description of the deposited material sufficient to comply with the written description requirement of (35 U.S.C.) § 112, 1.'26 (emphasis added).

Consequently, Enzo's disclosure coupled with the deposit of the cell lines constituted an adequate written description of the invention defined by the claims directed to those deposited lines.27 Nevertheless, other claims in the patent were broader, encompassing more than the sequences expressed by the deposited cell lines. Remanding the case to the district court, the Federal Circuit stated that it was a question of fact whether the generically claimed sequences were adequately described by the Enzo specification.

B.   The Written Description Sword was Blocked Again in Amgen v. Hoescht Marion Roussel, Inc.

In Amgen, Inc. v. Hoescht Marion Roussel, Inc., the Federal Circuit rejected arguments that the claims at issue were invalid for failing to satisfy the written description requirement.28 Although other patents were involved in the litigation and discussed in the Federal Circuit's opinion, it was Amgen's U.S. Patent 5,547,933 ('the '933 patent') that was challenged under the written description requirement.29 The invention at issue in the '933 patent was a non-naturally occurring EPO product described by certain functional characteristics and the '933 patent disclosed a method of producing EPO in two species of vertebrate or mammalian cells.30

In its opinion, the Federal Circuit noted that the written description 'requirement may be satisfied if, in the knowledge of the art, the disclosed function is sufficiently correlated to a particular, known structure.'31 The Federal Circuit went on to distinguish Eli Lilly and Enzo 'because the claim terms at issue here are not new or unknown biological materials that ordinarily skilled artisans would easily miscomprehend.'32 Rather, the Court held that the terms in the specification, 'vertebrate' and 'mammalian' were sufficiently well known as to 'readily 'convey [ ] distinguishing information concerning [their] identity' such that one of ordinary skill in the art could 'visualize or recognize the identity of the members of the genus.''33

C.   The Written Description Sword Hits Its Mark in University of Rochester v. Searle & Co.

The district courts have followed the Federal Circuit's lead on written description. Most recently in University of Rochester v. Searle & Co, Inc., a case watched closely by the biotech and pharmaceutical industries, the District Court for the Western District of New York, found U.S. Patent 6,048,850 ('the '850 patent') invalid for failure to satisfy the written description requirement on a motion for summary judgment.34

The invention at issue in the '850 patent is a pharmaceutical 'method for selectively inhibiting PGHS-2 activity in a human host' in which 'the activity of PGHS-1 is not inhibited.'35 PGHS 1 and 2 are both enzymes that play a role in the manufacture of hormones known as prostoglandins. Prostoglandins produced by the activity of PGHS-1 help protect the stomach lining whereas prostoglandins produced by the activity of PGHS-2 cause pain and inflammation.36 Typical pain relievers inhibit the activity of both PGHS-1 and 2, which results in relief from pain but also stomach upset and irritation.

The '850 patent disclosed an assay for determining whether a compound is capable of inhibiting the activity of PGHS-2, without affecting the activity of PGHS-1. The assay involved contacting genetically engineered cells containing either PGHS-1 or PGHS-2, but not both, with a compound suspected of being able to inhibit PGHS-2 but not PGHS-1. However, the '850 patent did not disclose a working example where the assay was actually used to identify even a single compound with these desired characteristics.

In holding these broad claims invalid on summary judgment, the Court noted that the 'patent does no more than describe the desired function of the compound called for' and nowhere 'does it specify which 'peptides, polynucleotides, and small organic molecules' have the desired characteristic of selectively inhibiting PGHS-2.'37 (emphasis original). The court also noted that although the patent mentioned one compound, NS-398, as a 'specific inhibitor of PGHS-2,'38 the inventors testified that they were not sure whether NS-398 can actually be used in the claimed method.39

The district court, noting that the PTO Guidelines state that the written description requirement can be met by disclosing ''sufficiently detailed, relevant identifying characteristics,' including 'functional characteristics when coupled with a known or disclosed correlation between function and structure. . . .' (emphasis added) found the failure to disclose even a single compound or structure to be fatal to the validity of these broad claims.40

This case was closely watched by the biotech and pharmaceutical industries because several companies, such as Pfizer, Inc. had, in fact, discovered and marketed compounds that had this selective inhibition of PGHS-2. The debate had raged as to whether this early discovery of this proposed selective function along with an assay to find a compound to serve this function-without the discovery of even a single compound-entitled the University to cover all compounds subsequently discovered to serve the function, whether or not the specific assay was used in the discovery. At this time, everyone is waiting to see if the Federal Circuit will affirm this decision.

IV.   Conclusion

As the cases and Guidelines state, the one who describes his biological invention solely in functional terms without any correlation to a known or disclosed structure will not satisfy the written description requirement. It thus behooves the prudent practitioner to obtain as much information from the inventors as possible, such as partial structures, physical or chemical properties, other distinguishing features, or a deposit of biological material. Armed with this information, the practitioner can successfully thwart the sword of the written description requirement.


135 U.S.C. § 112, 1 (2003).

2Regents of the Univ. Of Calif. v. Eli Lilly & Co., 119 F.3d 1559 (Fed. Cir. 1997).

3Id. at 1562.

4Id. at 1563.

5Id. at 1567.



8Id. at 1568.

9Guidelines for the Examination of Patent Applications Under the 35 U.S.C. § 112, 1, 'Written Description' Requirement, 66 Fed. Reg. 1099, 1104-1111 (Jan. 5, 2001) ('Guidelines').

10See Molins PLC v. Textron, Inc., 48 F.3d 1172, 1180 n.10 (Fed. Cir. 1995).

11See Enzo Biochem, Inc. v. Gen-Probe Inc., 323 F.3d 956, 964 (Fed. Cir. 2002) ('Enzo II').

12Guidelines, 66 Fed. Reg. at 1105.



15Id. at 1106.


17See Deposit of Biological Material, 37 CFR § 1.801-1.825 (2002).

18Enzo Biochem, Inc. v. Gen-Probe Inc., 285 F.3d 1013 (Fed. Cir. 2002) ('Enzo I') rev'd on rehearing, 323 F3d 956 (2002) ('Enzo II'), rehearing en banc denied 2002 U.S. App. LEXIS 14412 (2002) ('Enzo III').

19Enzo II, 323 F.3d at 960-61.

20Id. at 961.

2137 CFR § 1.801-1.825.

22Enzo II, 323 F.3d at 962 citing Tr. of Hr'g at 42, Enzo Biochem, Inc. v. Gen-Probe, Inc., No. 99-CV-4548 (S.D.N.Y. Jan. 24, 2001).

23Enzo I, 285 F.3d at 1018.

24Enzo II, 323 F.3d. at 958.


26Id. at 965. The Court also noted that this was a matter of first impression.


28Amgen Inc. v. Hoechst Marion Roussel, Inc., 314 F.3d 1313, 1319 (Fed. Cir. 2003).

29Id. at 1330-34.

30Id. at 1330-32.

31Id. See also Enzo II, 323 F.3d at 967-68.

32Amgen, 314 F.3d at 1332.

33Amgen, 314 F.3d at 1332 quoting Eli Lilly, 119 F.3d at 1567, 1568.

34University of Rochester v. Searle & Co., Inc., 2003 U.S. Dist. LEXIS 3030 (WDNY Mar. 5, 2003).

35Id. at * 4.


37Id. at *21.

38'850 Patent, col. 28, line 40.

39University of Rochester, at *21, n. 4.

40Id. at *36-*37.