Aventis Pharma S.A. v. Amphastar Pharmaceuticals, Inc.

Facts

Plaintiff held the '618 patent, which was surrendered when Plaintiff received the '743 patent. Both patents related to a composition made up of low molecular weight heparins. The drugs, marketed as Lovenox in the United States and Clexane in Europe, work to prevent blood clotting and to minimize the chance of hemorrhaging, especially during high-risk surgery. The advantage claimed by the patented drugs is that they exhibit a longer half-life compared to heparin. At first, the patent claims were rejected based on obviousness and anticipation because the prior art, especially European Patent '144, taught a product that was almost identical. Plaintiff disputed the rejections arguing that the half-life of the new drugs was significantly longer, which demonstrate a difference in structure. Plaintiff continued to rely on the difference in half-life in the appeals that followed until the patent was allowed. Plaintiff later sued Amphastar Pharmaceuticals, Inc. (Defendant) for patent infringement claiming they made and marketed the drug in generic versions. The district court considered Defendant's argument that the patent was invalid, and held the half-life improvement to be relevant to patentability because that was the reason the patent was finally issued by the examiner. The district court found Plaintiff had intent to deceive the examiner because Plaintiff provided no credible explanation for its reliance on an allegedly improved half-life when it had compared half-life at different doses without disclosing this dosage information. When compared at the same doses, the half-life was about the same. The district court granted summary judgment to Defendant and declared the patent was not enforceable due to inequitable conduct, which was intent to deceive. Plaintiff appealed to this court claiming the dose information was not relevant to the patentability because otherwise the examiner would have requested it when half-life data was presented to her. Plaintiff also claimed its expert, Dr. Andre Uzan, informed the examiner of the difference in dose when his declaration stated "it enables the same effect to be achieved with lower dosages." This court held Dr. Uzan's statement did not completely inform the examiner and the absence of dose information was a failure to disclose relevant information. The dose information was relevant to the issue of patentability. However, this court remanded for the district court to determine intent to deceive if the different dose comparison was reasonable within the field and therefore failure to disclose was unintentional. On remand, regarding the limited issue of intent to deceive, the district court held a bench trial and again found Plaintiff had intent to deceive the examiner. Plaintiff appealed again.