1. Federal Circuit Reconsiders Ruling in 'Enzo Biochem'; Court Takes
More Flexible View of the Written-Description Requirement
MONDAY, OCTOBER 14, 2002
T
HE U.S. COURT OF APPEALS for the
Federal Circuit recently took an unusual
second look at the written description
requirement for biotechnology-related patents
in the July 15 decision, Enzo Biochem v. Gen-
Probe, 296 F.3d 1316 (Fed. Cir. 2002). The
court had originally rendered a decision on
April 2, in Enzo Biochem Inc. v. Gen-Probe
Inc., 285 F.3d 1013 (Fed. Cir. 2002) (Enzo I).
The court, however, reconsidered and vacated
its earlier decision in favorof one which
accords greater deference to the U.S. Patent
and Trademark Office (PTO) in evaluating
the written-description requirement for
biotechnology patents, and permits more
flexibility in using functional characteristics to
describe genetic material.
Despite the notorious complexity of
genetic sequences and structures, and
the difficulty in predicting corresponding
functions, patent applicants still must satisfy
the usual rigorous standards for obtaining a
patent. The U.S. patent statute requires all
patents to contain a written description in
such full, clear, concise and exact terms as to
enable those skilled in the art to make and use
the invention. 35 U.S.C. 112, 1.
In three cases decided in the 1990s, the
Federal Circuit found purely functional
characteristics to be insufficient to describe
genetic material. In 1991, the court held in
Amgen Inc. v. Chugai Pharmaceutical Co.,
927 F.2d 1200, 1206 (Fed. Cir. 1991), that
a conception of genetic material does not
occur until one can define it other than by its
biological activity or function--specifically that
it was insufficient to define a gene solely by its
ability to encode human erythropoietin.
In 1993, the court held in Fiers v. Revel,
984 F.2d 1164, 1171 (Fed. Cir. 1993), that
an adequate written description of DNA
requires a precise definition, such as by
structure, formula, chemical name or physical
properties, and not a mere plan for obtaining
it. Specifically, it held that a conception of
DNA which codes for -interferon was not
established until the complete nucleotide
sequence was disclosed.
In 1997, the court stated in Regents of
the University of California v. Eli Lilly & Co.,
119 F.3d 1559 (Fed. Cir. 1997), that claimed
genetic material may not be defined solely by
a statement of its function or result. In that
case, a description of rat insulin cDNA was not
sufficient to support a claim to a broad class of
vertebrate or mammalian insulin cDNA.
The guidelines
To address the Federal Circuit’s precedent,
the PTO published Interim Written escription
Guidelines in mid-1998. 63 Fed. Reg. 32639
(June 15, 1998). The PTO stated that the
guidelines were intended to assist PTO
personnel in view of Lilly, Fiers and Amgen.
The PTO received a number of comments,
some of which suggested generalizing the
guidelines beyond the area of biotechnology.
The PTO adopted this suggestion in late 1999.
Revised Interim Guidelines, 64 Fed. Reg.
71427 (Dec. 21, 1999). In early 2001, the PTO
issued its final Guidelines for Examination of
Patent Applications Under the 35 U.S.C. 112,
1, Written Description Requirement, 66 Fed.
Reg. 1099 (Jan. 5, 2001).
Although the guidelines are now general,
biotechnology-specific guidance can still be
found in the PTO’s responses to comments
and in footnotes to the guidelines. In addition,
the PTO published training materials that
includes a number of biotechnology examples.
The training materials are not published in
the Federal Register, but may be downloaded
from www.uspto.gov/web/menu/written.pdf.
General principles
The guidelines set forth general legal
principles and a methodology for determining
whether patent claims are supported by
an adequate written description. The most
emphasized point throughout the guidelines
is that the description must be sufficient to
enable one skilled in the art to recognize
clearly that the applicant had possession
of the claimed invention at the time it was
made.
The guidelines offer significant flexibility
in the use of functional characteristics to
describe genetic material. Specifically, they
state that an invention can be sufficiently
disclosed not only by structure and other
physical and/or chemical properties, but also
by functional characteristics coupled with
a known or disclosed correlation between
function and structure, or some combination
of such characteristics. 66 Fed. Reg. at 1106.
The training materials also provide supporting
and contrasting examples; e.g., compare
training materials, at 27-29, with id. at 53-55.
As of early 2002, it remained to be
seen how or whether the Federal Circuit
would consider the PTO guidelines and
training materials in view of the court’s
earlier precedent. See, e.g., Lawrence T.
Kass and Michael N. Nitabach, A Roadmap
for Biotechnology Patents? Federal Circuit
Precedent and the PTO’s New Examination
Guidelines, 30 AIPLA Q.J. 233, 253, 264-65
(2002). The court provided one short-lived
answer to that question in its Enzo I decision.
Plaintiff Enzo Biochem Inc. had sued
Gen-Probe Inc. for allegedly infringing a
patent that claimed nucleic acid probes by
reference to a biological deposit and to the
probes’ function of selectively hybridizing
to the DNA of N. gonorrhoeae, the bacteria
that cause gonorrhea. Previous probes had
difficulty accurately identifying this bacteria
because the DNA of N. gonorrhoeae exhibits
a high degree of homology with that of N.
meningitides, and consequently prior probes
erroneously showed positive results even
though only N. meningitides was present.
Gen-Probe moved for summary judgment
of invalidity, arguing that the patent only
defined the claimed DNA by its biological
function, and therefore did not satisfy the
written - description requirement under
Lilly and Fiers. The district court granted the
motion, and Enzo appealed. Enzo I, 285 F.3d
at 1015.
In the Enzo I opinion that followed, a
majority of a three-member Federal Circuit
panel addressed several aspects of the written-
description requirement. Among other things,
the court held that a biological material must
be described by more than a statement that it
exists in a depository. In addition, the court
considered the extent to which a functional
description of genetic material might satisfy
the written-description requirement. In doing
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2. so, the court arguably was not very deferential
to the guidelines. The court emphasized that
the guidelines are not binding upon the court
and, in any event, do not advocate a rule that
describing a compound by its binding affinity
is sufficient to satisfy 35 U.S.C. 112, 1. Id. at
1019.
Judge Timothy B. Dyk dissented, arguing
that the majority had incorrectly discounted
the description as merely functional, whereas
he viewed it as identifying a structural
difference. Id. at 1026. He emphasized
that the property of selectively binding to
particular DNAs directly results from the
structure of the hybridizing nucleotide
sequence. He stated that although the patent
did not disclose the target sequences and
structures, they were not novel and their
degree of homology was disclosed as being
between 80% to 93%, indicating that their
structures were at least somewhat known
to those of skill in the art. He argued that a
description may adequately disclose claimed
genetic material by describing its degree
of hybridization to nucleic acids of known
sequence. Id.
Federal Circuit’s second look
Enzo I received media attention and raised
concerns among a number of members in
the patent bar. See, e.g., Frank Porcelli and
Charles Sanders.
Enzo Raises the Bar for Written
Descriptions, NLJ, June 3, 2002, at C3. Enzo
filed a request for reconsideration and petition
for rehearing en banc, and shortly thereafter
amici curiae filed two briefs in support of
Enzo’s petition for rehearing, one of which
was filed by the United States; the solicitor of
the PTO was of counsel on the brief.
In the Enzo II decision issued on July
15, the three-judge Federal Circuit panel
of the original Enzo I appeal vacated the
earlier majority decision and expressly
acknowledged that not all functional
descriptions of genetic material fail to meet
the written-description requirement. Enzo
II, 296 F.3d at 1324. (Judge Alan D. Lourie
authored both Enzo I and Enzo II as well
as the prior decisions in Lilly, Fiers and
Amgen.) A significant factor in the court’s
reversal was its second, more deferential look
at the guidelines. The court acknowledged
that, according to the guidelines, the Enzo
patent could meet the written-description
requirement by the functional characteristic
of preferential binding to N. gonorrhoeae over
N. meningitides, coupled with a disclosed
correlation between that function and a
sufficiently known or disclosed structure. Id.
at 1324-25.
The Federal Circuit stated that [w]e are
persuaded by the Guidelines on this point
and adopt the PTO’s applicablestandard for
determining compliance with the written
description requirement. Id.
The Federal Circuit then considered Enzo’s
incorporation by reference of deposits in the
written description. The court found that the
incorporation by reference constitutes an
adequate disclosure of the deposit sequences
because one skilled in the art could obtain
deposit samples and sequence their DNA by
following appropriate techniques. Id. at 1326.
However, the court remanded with regard to
claims covering a broader genus of sequences
meeting a hybridization ratio of greater than
about five, for the factual determination of
whether one skilled in the art would glean that
the inventors had possession of the numerous
subsequences, mutated variants and mixtures
corresponding to this hybridization ratio. Id.
at 1326-27.
The Federal Circuit then addressed
two similar but distinct issues relating to
hybridization. First, the court questioned
whether the property of hybridizing to known
sequences of deposited material could itself
amount to a sufficient description. On this
issue, the court relied on example 9 of the
training materials, wherein known nucleic
acids are used to hybridize with and thereby
isolate other nucleic acids. The example
notes that one would not expect substantial
variation among species due to the rigid
hybridization conditions. Training materials,
at 35-37.
In view of this example, the Federal Circuit
concluded that Enzo’s claimed sequences
might be adequately described by the
disclosed hybridization with known sequences
under the conditions set forth in the patent.
The court remanded this issue to the district
court for this factual determination.
Second, the Federal Circuit addressed
whether the claimed sequences could be
adequately described by the function of
hybridization along with a correlation to
the complementary structural relationship
between the claimed sequences and that
of N. gonorrhoeae DNA. The court held
that the function of preferentially binding
to N. gonorrhoeae DNA could, under PTO
guidelines, adequately describe the claimed
sequences, so long as they are correlated to
deposited structures which are accessible to
the public, even though they are not explicitly
sequenced. The court therefore directed the
district court on remand to consider whether
one skilled in the art would find the sequences
to be described by the hybridization function
and publicly accessible structure, consistent
with the PTO guidelines. Id. at 1328.
Finally, the court clarified the significance
of possession and actual reduction to practice
of an invention in relation to the written-
description requirement. The court stated
that demonstrating possession of an invention
is a purpose of, but is not always sufficient
to meet, the statutory written-description
requirement. Similarly, reduction to practice
does not necessarily satisfy the requirement.
Although the requirement may be satisfied in
MONDAY, OCTOBER 14, 2002
biological cases by a deposit and a reference
to the deposit accession number, it is not
satisfied by reason of a reduction to practice.
On the petition for rehearing en banc, all
panel members of Enzo II voted along with
Judge Pauline Newman against granting the
petition, and judges Richard Linn, Randall
R. Rader and Arthur Gajarsa dissented. Their
respective opinions are unpublished but
available online. 2002 WL 1592885 (Fed. Cir.
2002).
Enzo II is highly significant in according
deference to the guidelines and in recognizing
that, for biotechnology patents, functional
characteristics can be used to meet the
written-description requirement. In addition,
the decision provides specific guidance
regarding biological deposits, and more
general guidance on the significance to the
written-description inquiry of possession and
reduction to practice of the invention.
Lawrence T. Kass is an associate in the
intellectual property/litigation group at New
York’s Milbank, Tweed, Hadley & McCloy.
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