Revisiting Therasense, CAFC finds that an inventor’s subjective belief that submission of documents was unnecessary may not be sufficient to avoid a showing of intent to deceive

Shuji Yoshizaki | April 18, 2012


Aventis Pharma S.A. and Sanofi-Aventis U.S. LLC v. Hospira Inc. and Apotex Inc.

April 9, 2012

Panel:  Linn, Dyk, and Prost; Opinion by Prost


The court found that the patents were invalid over withheld references, and unenforceable for inequitable conduct.

If the patentee did not narrow the ordinary meaning of  a claim term by either acting as its own lexicographer or disclaiming claim scope either in the specification or during prosecution, that  claim term cannot be interpreted more narrowly than its ordinary meaning.

If the claims at issue are found invalid over a withheld reference under the clear and convincing evidence standard, then the withheld reference is found but-for material under the preponderance of evidence in Therasense; in this case, the materiality requirement was met since the patents were invalid based on the withheld references.

The witness’ explanation that that he believed he did not need to disclose the references to the PTO may not be sufficient to show that there was no specific intent to deceive the PTO because that finding was not the single most reasonable inference that could be drawn, unless the testimony is credible and the evidence presented is supported.  The reference disclosing the information that shaped the inventive thinking should be cited, and there is no justification for telling the PTO about the prior art disclosing the problem an inventor examined while concealing key prior art disclosing the solution he chose.



クレームが明確かつ説得力ある証拠基準の下、提出しなかった文献によって無効であると判断された場合、その文献は、必然的に、Therasense事件の証拠優劣基準に基づくbut for material(すなわち、その非開示の先行文献を特許庁が知っていたならば特許庁は特許を許可しなかったであろう、というレベルの関連性があること)の要件を満たす。本件では、特許が提出されなかった文献によって無効であると判断されたため、不公正行為立証の要件の一つであるbut-for materialityの要件を満たす。




The ’561 and ’512 patents are pharmaceutical patents related to the administration of the chemotherapy cancer drug docetaxel, which is marketed under the brand-name Taxotere.   Taxanes are administered by slowly delivering the drug in a diluted aqueous solution called a “perfusion.”  Taxanes, however, have low solubility in water and tend to precipitate.  To delay precipitation, taxanes are mixed with additives like surfactants and ethanol.  The taxane is combined with the additives to form a “stock solution” which is then mixed into an injectable aqueous solution to form a perfusion.

In the prior art, the surfactant Cremophor was used to form the stock solution, but it was known to trigger serious allergic reactions, including anaphylactic shock.  The ’561 and ’512 patents relate to using surfactants other than Cremophor and decreasing the amount of ethanol to reduce alcohol intoxication and anaphylactic effects.  After Hospira and Apotex applied for Federal Drug Administration (“FDA”) approval to market generic versions of Taxotere, Sanofi filed suit against them for infringement of the ’561 and ’512 patents.  Only claim 5 of the ’561 patent and claim 7 of the ’512 patent are at issue on appeal.

Claim 5 of the ’561 patent recites:

1. A perfusion, which contains approximately 1 mg/ml or less of compound of formula as defined in claim 1, and which contains less than 35 ml/l of ethanol and less than 35 ml/l of polysorbate, wherein said perfusion is capable of being injected without anaphylactic or alcohol intoxication manifestations being associated therewith.

Claim 7 of the ’512 patent recites:

1. A composition comprising a compound of the formula in which Ar is unsubstituted phenyl, R7 is phenyl or tert butoxy, R6 is hydrogen, R5 is acetyloxy or hydroxy, R3 and R4 taken together form an oxo radical, R1 is hydroxy and R2 is hydrogen, said composition being dissolved in a surfactant selected from polysorbate, polyoxyethylated vegeta-ble oil, and polyethoxylated castor oil, said composition being essentially free or free of ethanol.

6. The composition of claim 1, wherein R5 is hydroxy and R7 is tert butoxy.

7. The composition of claim 6, wherein said surfactant is polysorbate.

After a bench trial, the court found that the claims of the patents were invalid as obvious.  The court also determined that the patents were unenforceable for inequitable conduct.

On appeal, Sanofi challenged the district court’s claim construction and the finding of the inequitable conduct.

Claim Construction

Claim 5 of the ’561 Patent

Sanofi asked the district court to require that the claimed “perfusion” also be effective for treatment, safe, and stable (i.e., not precipitate) for at least eight hours.  The district court declined to impose these additional limitations and instead construed “perfusion” to mean “an injectable solution containing the active pharmaceutical ingredient and an aqueous infusion fluid.”

On appeal, Sanofi argued that the district court erred in construing “perfusion” without those limitations.  CAFC, however, rejected it since neither the claims, the specification, nor the prosecution history suggest that the claimed perfusion must satisfy certain safety or efficacy standards.  In Thorner v. Sony Computer Entertainment America L.L.C., 669 F.3d 1362 (Fed. Cir. 2012), CAFC explained that a claim term can be interpreted more narrowly than its ordinary meaning under two circumstances: “1) when a patentee sets out a definition and acts as [its] own lexicographer, or 2) when the patentee disavows the full scope of a claim term either in the specification or during prosecution.”

CAFC concludes that the patentee did not narrow the ordinary meaning of “perfusion” in the patent, and therefore agrees with the district court’s claim construction of the term “perfusion.”

Then, CAFC affirmed the district court’s conclusion that claim 5 was invalid as obvious under 35 U.S.C. § 103 over prior art, including the Guéritte-Voegelein reference (“GV reference”) and the Dictionnaire Vidal (“Vidal reference”).

Claim 7 of the ’512 patent

Sanofi argues that the district court erred in construing the claim term “essentially free or free of ethanol” in claim 7 of the ’512 patent as meaning that the claimed perfusion contains “the same amount of ethanol as a stock solution with no more than 5% ethanol by volume.”

CAFC refused to reconsider it since Sanofi did not addressed the district court’s obviousness finding with respect to stock solutions in its opening brief.  CAFC accordingly affirmed the district court’s judgment that claim 7 of the ’512 patent is invalid under 35 U.S.C. § 103.

Inequitable Conduct

The district court found that the Vidal and GV references were material to patentability and that inventor Fabre intentionally withheld them with the intent to deceive the USPTO.

In CAFC, Sanofi argued that because Fabre explained why he did not disclose these references, the court’s finding that he acted with the intent to deceive was not the single most reasonable inference that could be drawn from the evidence.


A prior art reference “is but-for material if the PTO would not have allowed a claim had it been aware of the undisclosed prior art.”  Therasense, 649 F.3d at 1291.  Unlike the clear and convincing evidence standard for invalidating a patent in the district court under 35 U.S.C. §§ 102 and 103, the standard for establishing but-for materiality in the inequitable conduct context only requires a preponderance of the evidence, “giving claims their broadest reasonable construction.” Id. at 1291-92.  As a result, when a “claim is properly invalidated in district court based on the deliberately withheld reference, that reference is necessarily material” for purposes of the inequitable conduct inquiry. Id. at 1292.  On the other hand, even if the withheld reference is not sufficient to invalidate the claim in district court, “the reference may be material if it would have blocked patent issuance under the PTO’s different evidentiary standards.” Id.

Here, CAFC has affirmed the district court’s finding that the ’561 and ’512 patents were invalid based on the withheld references. Therefore, CAFC decided that the district court did not err in finding that the materiality requirement was established.


To satisfy the intent requirement, “the accused infringer must prove by clear and convincing evidence that the applicant knew of the reference, knew that it was material, and made a deliberate decision to withhold it.”  In Therasense, inequitable conduct requires clear and convincing evidence of a specific intent to deceive the PTO and that “the specific intent to deceive must be ‘the single most reasonable inference able to be drawn from the evidence.’” The Therasense court rejected the “sliding scale” approach in proving inequitable conduct

In this case, the district court heard extensive testimony from inventor Fabre regarding both the Vidal and GV references.  The Vidal reference discloses an experience using polysorbate 80 as a surfactant with the cancer drug etoposide.  Fabre testified that he did not cite the Vidal reference because the etoposide-type experiments he and his co-inventors performed with doxcetaxel did not demonstrate eight hours of stability.  Fabre explained that he believed that these experiments were failures and that he therefore did not need to disclose the reference to the PTO.  Based on this testimony, Sanofi argued that the district court erred in finding that Fabre had the specific intent to deceive the PTO because that finding was not the single most reasonable inference that could be drawn.

CAFC disagreed.  The district court had considered Fabre’s explanation for withholding the Vidal reference and expressly rejected it based on both the evidence presented and the finding that Fabre lacked credibility.  Specifically, the district court relied on Fabre’s testimony that he learned of replacing Cremophor with polysorbate 80 from the Vidal reference and that the experience in the Vidal reference was one of the “main factors that shaped [his] thinking” in choosing polysorbate 80 and led him to believe that replacing Cremophor with polysorbate 80 would avoid anaphylactic manifestations.

The district court also emphasized that Fabre and his co-inventors submitted to the PTO the Rowinsky reference, which identified the “problem” the inventors were trying to solve—i.e., the anaphylactic reactions associated with Cremophor—but did not cite the Vidal reference, which revealed the “solution”—i.e., the switch from Cremophor to polysorbate 80.  The court found that “[t]here simply is no justification for telling the [PTO] about the prior art disclosing the problem [Fabre] examined while concealing key prior art disclosing the solution he chose.”

Regarding the GV reference, CAFC reached the same conclusion. The reference discloses: “Moreover Taxotere (13a) showed a better solubility in excipient system (polysorbate 80/ethanol, 1:1) . . . .”  Fabre testified that he did not cite the GV reference to the PTO because he only read a March 1990 draft of the reference which did not include this sentence disclosing the polysorbate 80/docetaxel formulation.

Again, the district court found that this testimony was not credible.  Fabre was the project leader of Sanofi’s Taxotere development, had to approve the GV reference for publication, and had testified that he reviewed the article “with some care to make sure that it was a proper article for the company to be publishing.”  The district court highlighted Fabre’s testimony that in March 1992, he was dissatisfied with the clinical brochure for Taxotere because it did not list the GV reference and affirmatively took steps to identify the reference.  Six months later, however, when Fabre signed his patent declaration, he failed to disclose the reference.  Relying on this evidence, the district court found that Fabre “‘reviewed . . . with some care’ the final version of the GV reference prior to signing the patent declaration, was aware of the reference’s materiality to the prosecution of his patents, and purposefully decided not to disclose it despite this knowledge.”

Relying on these materiality and intent findings, the district court found inequitable conduct.  Based on the district court’s thorough discussion of its factual findings and its well-reasoned analysis that is consistent with Therasense, this determination was not an abuse of discretion.  CAFC accordingly affirmed.


The patent applicants should disclose every reference considered to conceive the inventive idea, including references disclosing problems, solutions, or similar experiments.  Do not forget to disclose inventor’s own articles or prior applications which disclose the same solution as the present application.

Full Opinion

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