Federal Circuit Affirms Unenforceability of Taxotere Patents

09 April 2012 PharmaPatents Blog
Author(s): Courtenay C. Brinckerhoff

In Aventis Pharma S.A. v. Hospira, Inc., the Federal Circuit upheld the district court’s finding that two of the Orange Book listed patents for Sanofi Aventis’ cancer drug Taxotere are unenforceable for inequitable conduct.  The Federal Circuit found that the district court’s analysis followed the framework required by its 2011 en banc decision in Therasense, even though the district court rendered its decision before that case was decided en banc.

The Patents At Issue

The patents at issue were U.S. 5,750,561 and U.S. 5,714,512.  As summarized by the Federal Circuit, the patents relate to formulations of the cancer drug docetaxel that are designed to overcome problems with stability and toxicity encountered with prior art formulations.  The patents address these problems by using certain surfactants and by limiting the amount of ethanol.


The district court found that claim 5 of the ’561 patent and claim 7 of the ’512 patent were invalid as obvious in view of prior art including a publication by Guéritte-Voegelein (the “GV reference”) and the Dictionnaire Vidal (the “Vidal reference”). Although Sanofi Aventis challenged the claim construction underlying these findings, it had conceded that if the district court’s claim construction was upheld, the claims would be obvious.  Since the Federal Circuit found no error in the district court’s claim construction, it affirmed the findings of obviousness.


The district court found that both patents were unenforceable due to inequitable conduct based on the intentional non-disclosure of the GV reference and the Vidal reference. The Federal Circuit determined that “although the district court did not have the benefit of our Therasense opinion when it rendered its inequitable conduct decision, . . . we conclude that the court’s inequitable conduct determination withstands even the more rigorous standard adopted in Therasense.”

“But For” Materiality

As noted above, the inequitable conduct charges stemmed from the non-disclosure of two references found to invalidate one claim in each patent.  The Federal Circuit cited this guidance from Therasense for the proposition that the invalidity rulings demonstrate that the references at issue satisfy the “but for” test for materiality:

[W]hen a “claim is properly invalidated in district court based on the deliberately withheld reference, then that reference is necessarily material” for purposes of the inequitable conduct inquiry.

Intent To Deceive

The Federal Circuit reviewed listed these principles as underlying the “intent” requirement of an inequitable conduct case:

  • 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.
  • Inequitable conduct requires clear and convincing evidence of a specific intent to deceive the PTO.
  • The specific intent to deceive must be “the single most reasonable inference able to be drawn from the evidence.”

The court noted that, in the case before it, “the district court heard extensive testimony from inventor Fabre regarding both the Vidal and GV references, and the court’s finding that Fabre acted with a specific intent to deceive the PTO in withholding those references is not clearly erroneous.”

With regard to the Vidal reference, Sanofi Aventis cited the inventor’s testimony that related experiments that he had conducted were “failures” and that he therefore believed that he did not need to disclose the Vidal reference. The district court found that testimony to be not credible for a number of reasons.  Additionally, the district court cited the inventor’s testimony that he learned from the Vidal reference to replace the surfactant used previously with the surfactant recited in the claims, and his testimony that the Vidal reference was one of the “main factors that shaped [his] thinking” in choosing the surfactant. The Federal Circuit noted that the testimony cited by the district court “was consistent with a Sanofi internal memorandum.”  The Federal Circuit also noted that the district court had emphasized that the inventors had painted an incomplete picture of the prior art as recognizing a problem with the surfactant used previously but not as recognizing a possible solution, as suggested by the Vidal reference.  The district court therefore found that the inventor “knew that the Vidal reference and the other etoposide prior art were relevant to the patentability of his alleged invention, but nonetheless chose not to disclose it to the patent office,” and so had acted with intent to deceive. The Federal circuit found no reason to overturn this finding as clearly erroneous.

With regard to the GV reference, Sanofi Aventis cited the inventor’s testimony that he did not disclose the references because he only had read a draft that did not include the most relevant passage. The district court found that this testimony was not credible because, for example, he “was the project leader,” “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 also cited the inventor’s testimony that he took steps to revise the clinical brochure for Taxotere because it did not list the GV reference, but still did not cite the reference to the Patent Office.  Again, the Federal Circuit found no  reason to overturn this finding as clearly erroneous.

Having upheld the district court’s findings of “but for” materiality and a specific intent to deceive the Patent Office, the Federal Circuit found no abuse of discretion in the district court’s judgment of unenforceability.

An “Easy” Case?

Although Therasense raised the bar for establishing the “materiality” prong of inequitable conduct, this case was an “easy” one on that issue, because of the parallel obviousness findings. The Federal Circuit here did not have to put itself in the shoes of the Patent Office, asking the hypothetical question whether references that might not invalidate a patent under a clear and convincing standard nonetheless might have prevented the patent from granting under a preponderance of the evidence standard. It will be interesting to see the court’s analysis when it has to grapple with such a fact pattern.

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