United States Court of Appeals 

for the Federal Circuit ______________________ 

SANOFI-AVENTIS,

Appellant,

v.

PFIZER INC.,

Appellee.

______________________ 

2012-1345

______________________ 

Appeal from the United States Patent and Trademark 

Office, Board of Patent Appeals and Interferences in No. 

105,757. 

______________________ 

Decided: November 5, 2013

______________________ 

Thomas J. Vetter, Lucas & Mercanti, LLP, of New 

York, New York, argued for appellant. 

Z. Ying Li, Ropes & Gray, LLP, of New York, New 

York, argued for appellee. With her on the brief was 

James F. Haley, Jr. 

______________________ 
2 SANOFI-AVENTIS v. PFIZER INC. 

Before NEWMAN, and LOURIE, Circuit Judges, and DAVIS,

District Judge.1

NEWMAN, Circuit Judge. 

Sanofi-Aventis (“Sanofi”) appeals the decision of the 

United States Patent and Trademark Office (“PTO”) 

Board of Patent Appeals and Interferences (“the Board”),2

awarding priority of invention to Pfizer Inc. (“Pfizer”)

based on the following interference count:

Count 3. The isolated protein of 6,268,480 claim 

4;

OR

The isolated polynucleotide of 5,710,023 claim 1, 

selection (b) (an isolated polynucleotide comprising a nucleotide sequence of SEQ ID NO:3 from 

nucleotide 103 to nucleotide 1242). 

Nucleotides 103 to 1242 constitute the protein-encoding 

portion of the complementary deoxyribonucleic acid 

(“cDNA”) for the human interleukin-13 receptor binding 

chain (“IL-13bc”).

The parties disagree as to the dispositive question in 

the interference. As summarized by Pfizer, the question 

is “who first had in hand the actual isolated DNA of the 

count and appreciated its IL-13bc function.” Pfizer Br. 1. 

As summarized by Sanofi, the question is “the date each 

party first knew the complete sequence” of nucleotides 

1 The Honorable Leonard Davis, Chief Judge, United States District Court for the Eastern District of Texas, 

sitting by designation.

2 Sanofi-Aventis v. Pfizer Inc., Patent Interference 

No. 105,757 (Bd. Pat. App. & Int. Jan. 5, 2012). Pfizer 

was substituted for Genetics Institute as the real party in 

interest. 

 
SANOFI-AVENTIS v. PFIZER INC . 3

103 to 1242. Sanofi Br. 4. The Board agreed with Pfizer 

that possession and appreciation of the actual isolated 

DNA is the dispositive question for priority of conception 

for an interference count directed to the isolated DNA, 

and on that basis awarded priority to Pfizer.

BACKGROUND

IL-13 is a regulatory molecule called a cytokine. Cytokines function by interacting with cytokine receptors 

located on target cells. The subject of this patent interference is a DNA polynucleotide that encodes the protein 

binding chain of the IL-13 receptor. Both Sanofi and 

Pfizer were conducting research in this field of scientific 

endeavor, for therapeutic and diagnostic purposes, and

both Sanofi and Pfizer discovered and filed patent applications directed to the polynucleotide encoding the relevant IL-13 binding chain. 

In accordance with the applicable law,3 the patent is 

awarded to the first party to conceive and reduce to 

practice the invention represented by the interference 

count. See Cooper v. Goldfarb, 154 F.3d 1321, 1327 (Fed. 

Cir. 1998) (“[P]riority of invention goes to the first party 

to reduce an invention to practice unless the other party 

can show that it was the first to conceive of the invention 

and that it exercised reasonable diligence in later reducing that invention to practice.”). This law is implemented 

in accordance with rules and precedent, administered by 

the PTO Board (“Board”). On appeal to the Federal 

Circuit, we review the Board’s rulings of law for correctness, and factual findings for support by substantial 

evidence. See Dawson v. Dawson, 710 F.3d 1347, 1353 

(Fed. Cir. 2013) (“The issue of conception turns in large 

3 The America Invents Act (“AIA”), Pub. L. No. 112-

29, obviated patent interferences. Pursuant to AIA 

§3(n)(2)(A), this interference remains governed by the 

prior laws.

 
4 SANOFI-AVENTIS v. PFIZER INC. 

part on the facts, and we review the Board’s many factual 

findings in this case for substantial evidence.”). 

Sanofi was awarded the benefit of its December 6, 

1995 priority date. Pfizer’s filing date is March 1, 1996; 

Pfizer thus bore the burden of proving a date of conception earlier than the Sanofi benefit date. Pfizer presented 

documentary and testimonial evidence that it had isolated 

and identified the desired cDNA before the Sanofi benefit 

date. However, due to sequencing errors, Pfizer did not 

then have a completely accurate analysis of the entire 

nucleotide sequence. The Board found that Pfizer had 

“the claimed polynucleotide in hand with some additional 

identifying information including at least a partial sequence,” and ruled that Pfizer “established conception and 

actual reduction to practice of a polynucleotide within the 

scope of count 3” before the Sanofi benefit date. Bd. Op. 

at 17.

On appeal, Sanofi argues that Pfizer cannot be credited with conception because although Pfizer’s sequence 

analysis before the Sanofi date was correct as to 1135 of 

the 1143 nucleotides, the analysis was in error as to eight

nucleotides. The Board found that Pfizer corrected this 

analysis by February 7, 1996. The Pfizer patent application filed on March 1, 1996 contained the correct analysis. 

Sanofi argues that conception of the claimed cDNA could 

not be established for priority purposes until the fully 

correct nucleotide sequence was determined, because the 

interference count is directed to the isolated polynucleotide. Sanofi argues that until Pfizer had correctly analyzed the polynucleotide, neither conception nor reduction 

to practice could occur. Sanofi states that Federal Circuit 

precedent requires the full and correct nucleotide sequence to establish conception, because reduction to 

practice, whether actual or constructive, requires the full 

and correct nucleotide sequence.
SANOFI-AVENTIS v. PFIZER INC . 5

The Board did not share Sanofi’s view of law and 

precedent. The Board held that Pfizer had established 

conception of the subject matter of the count when it 

selected, isolated, and obtained the desired IL-13bc fulllength polynucleotide and verified that it was the desired 

product, regardless of whether the fully correct sequencing of the polynucleotide was complete. Sanofi argues on 

this appeal that the Board erred in law.

DISCUSSION

As junior party with the burden of proof, Pfizer presented evidence of its research with murine and human 

IL-13 starting in early 1995. The Board found that coinventor Lori Fitz performed binding assays with commercially supplied human IL-13 in conjunction with 

recombinant murine IL-13bc protein fused to an antibody 

fragment known as the Fc domain. Ms. Fitz verified that 

the murine IL-13bc protein bound human IL-13 and that 

the interaction was specific, conducting experiments that 

showed that the protein could be blocked with excess 

murine IL-13bc fusion protein or with anti-human IL-13 

antibody.

After isolating the murine IL-13bc, by October 16, 

1995 Pfizer scientists isolated the human IL-13bc, called 

clone 11, from a human cDNA library. Co-inventor Matthew Whitters testified that he aligned the sequence of 

clone 11 with the respective sequences of the murine IL13bc, and summarized his conclusions:

[G]iven the size of the clone 11 insert (it corresponded to the mouse A25 full-length clone [i.e., 

murine IL-13bc]), the significant sequence identity and similarity between the amino acid sequence deduced from the nucleotide of the 5' end 

of the cDNA of the clone 11 insert and the mouse 

A25 protein, the identification of the 5' end of the 

cDNA and the confirmation that it encoded the Nterminus of the protein and the fact that the 
6 SANOFI-AVENTIS v. PFIZER INC. 

cDNA contained the 3' end of the coding sequence, 

on October 25, 1995, I was highly confident, and 

virtually positive, that the clone 11 insert contained the full-length nucleic acid coding sequence 

for the human homolog of the mouse A25 protein.

Whitters Decl. 6, Feb. 25, 2011. Mr. Whitters also testified that on November 15, 1995 he was provided with a 

computer printout of the nucleotide sequence of clone 11, 

and the next day he was provided with the deduced amino 

acid sequence encoded by that clone. He testified that the 

nucleotide sequence and amino acid sequence were 

checked for errors by comparison with the sequences for 

additional human IL-13bc products that Pfizer had isolated from its cDNA library. 

Whitters testified that for the polynucleotide sequence 

eight possible errors were found out of 1143 nucleotides, 

and that the encoded amino acid sequence was correct for 

379 out of 380 residues. He testified that correction of 

these sequences was completed by December 12, 1995 and 

confirmed by February 7, 1996.

It was not disputed that clone 11 was the desired 

product. Pfizer argued that its initial sequence was 99.3% 

accurate, and that the sequencing errors were routinely 

detected and corrected. The Board held that Pfizer had 

established conception and reduction to practice before 

the Sanofi benefit date.

Sanofi argues that as a matter of law Pfizer did not 

have a complete conception until Pfizer had the full 

correct nucleotide sequence, citing Federal Circuit precedent including Amgen Inc. v Chugai Pharmaceutical Co., 

927 F.2d 1200 (Fed. Cir. 1991). Amgen does not support 

Sanofi’s position. The court in Amgen held that when “an 

inventor is unable to envision the detailed constitution of 

a gene” there may nonetheless be conception and reduction to practice of the gene when the inventor is in possession of the gene and a method for its preparation, i.e.
SANOFI-AVENTIS v. PFIZER INC . 7

“after the gene has been isolated,” accompanied by

knowledge of “other characteristics sufficient to distinguish it from other genes.” Amgen, 927 F.2d at 1206. The 

Pfizer activity meets these criteria.

Sanofi argues that Fiers v. Revel, 984 F.2d 1164 (Fed. 

Cir. 1993) established a per se rule that conception of an 

isolated DNA requires the full and correct nucleotide 

sequence, and that this court limited Fiers to the filing 

date of his application that described the complete nucleotide sequence, and no earlier conception date. Sanofi 

states that this court recognized that “conception of DNA, 

like conception of any chemical substance, requires a 

definition of that substance other than by its functional 

utility” and that “[c]onception of a substance claimed per 

se without reference to a process requires conception of its 

structure, name, formula, or definitive chemical or physical properties.” Sanofi Br. 17-18, quoting Fiers, 984 F.2d

at 1169. Sanofi states that in Burroughs Wellcome Co. v. 

Barr Laboratories, Inc., 40 F.3d 1223, 1229 (Fed. Cir. 

1994) this court clarified that Fiers requires knowledge of 

the complete nucleotide sequence as a condition of conception. Sanofi argues that Pfizer did not have a “definite 

and permanent idea” of the complete and operative invention, as required by Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1376 (Fed. Cir. 1986).

The Board held that Pfizer met the requirements of 

precedent. The Board found that Pfizer had isolated clone 

11 and appreciated that it encoded the full-length human 

IL-13bc, had identified clone 11’s structural characteristics, and had correctly analyzed over 99% of the nucleotide sequence. The Board found that the inventors had 

obtained the operative DNA and had described the method for obtaining it. It is not disputed that the Pfizer 

scientists had isolated and obtained the IL-13bc DNA; the 

issue is whether conception is negated because the nucleotide sequence was not corrected until after the Sanofi 

benefit date of December 6, 1995.
8 SANOFI-AVENTIS v. PFIZER INC. 

The Board distinguished Fiers and Amgen as holding 

that conception and reduction to practice did not occur 

until the gene was isolated, for in those cases neither 

structure nor definitive properties had been established

for the isolated gene. Bd. Op. at 16. Burroughs Wellcome

did not change these requirements, in holding that conception requires that the claimed DNA is possessed as a 

physical embodiment. Knowledge of the specific nucleotide sequence was not required in Burroughs Wellcome. 

The Board elaborated that in this precedent the issue 

was not identification of the operative DNA by full nucleotide analysis, but isolation of the operative DNA and 

identification by distinguishing properties of the isolate. 

Amgen, 927 F.2d at 1206; Fiers, 984 F.2d at 1169. Amgen

and Fiers did not hold, as Sanofi asserts, that conception 

requires the complete and correct sequencing of the 

isolated DNA; the court instead referred to “whatever 

characteristics sufficiently distinguish it.” Amgen, 927 

F.2d at 1206. The Board was not persuaded by Sanofi’s 

argument that since the interference count is in terms of 

the nucleotide structure, Pfizer could not be credited with 

conception of the IL-13bc product until it knew the complete correct nucleotide sequence. Thus the Board held 

that Pfizer had achieved conception and reduction to 

practice before the Sanofi benefit date.

Precedent illustrates a variety of circumstances in 

which this requirement was met although the complete 

nucleotide sequence was not known. In Enzo Biochem, 

Inc. v. Gen-Probe Inc., 323 F.3d 956 (Fed. Cir. 2002) this 

court upheld claims for certain DNA probes that were 

made available by deposit in a public depository, as 

provided by the Rules and PTO practice, although the 

nucleotide sequence had not been determined. In University of New Mexico v. Knight, 321 F.3d 1111, 1122 (Fed. 

Cir. 2003), the court explained that “a chemical structure 

is simply a means of describing a compound; it is not the 

invention itself.” The court stated in In re Wallach, 378 
SANOFI-AVENTIS v. PFIZER INC . 9

F.3d 1330, 1333 (Fed. Cir. 2004) that when a protein was 

described by a partial amino acid sequence in addition to 

other characteristics sufficient to identify it, the inventors 

were in possession of the protein.

We conclude that the Board correctly based conception and reduction to practice on the possession of the 

isolated DNA segment that was shown to have the desired 

properties. When the subject matter is a DNA segment, 

conception requires possession and appreciation of the 

DNA segment that is claimed. See Invitrogen Corp. v. 

Clontech Labs., Inc., 429 F.3d 1052, 1063-64 (Fed. Cir. 

2005) (“[C]onception requires that the inventor appreciate 

that which he has invented. . . . The priority determination requires evidence that the inventor actually first 

made the invention, and that he understood his creation 

to have the features that comprise the inventive subject 

matter at bar.”). The Board found that Pfizer had successfully searched for and isolated the IL-13bc DNA 

segment, and possessed and appreciated the isolated IL13bc DNA before the Sanofi benefit date.

Discussing the consequences of Pfizer’s flawed sequence analysis that was corrected after the Sanofi priority date, the Board stated that “[f]or proteins and 

polynucleotide species, a sequence is the gold standard for 

identifying species with precision . . . . It does not, however, thereby follow that a sequence is the only way to 

identify the composition precisely.” Bd. Op. at 15. Upon 

selecting, isolating and characterizing clone 11 Pfizer was 

“able to define [the IL-13bc] so as to distinguish it from

other materials, and to define how to obtain it.” Amgen, 

927 F.2d at 1206. The Board’s findings are supported by 

substantial evidence.

On these findings, the Board held that Pfizer had conceived and reduced to practice the isolated polynucleotide 

of Count 3 before the Sanofi benefit date. We conclude 
10 SANOFI-AVENTIS v. PFIZER INC. 

that the Board applied the correct law. The award of 

priority to Pfizer is affirmed. 

AFFIRMED