US CAFC upholds Aventis Lovenox (enoxaparin) patent enforceability

On 10 April 2006, Judges Radar,
Schall and Prost of the United States Court of Appeal for the Federal Circuit
handed down their decision in Aventis Pharma SA v
Amphastar Pharmaceuticals [2006] CAFC
– 10 April 2006

Take home

While Aventis’s failure to disclose the correct
comparative data was material, there was insufficient evidence before the
District Court to base a finding of intent to deceive the USPTO on summary


In the latest round of a Hatch-Waxman paragraph IV dispute,
Aventis appealed a decision of the US District Court for the Central District
of California which granted summary judgment in favour of Amphastar and Teva
and held US Patent No. 5,389,618
and US Reissue Patent No. 38,743
unenforceable. The ‘618 and
‘743 patents claim mixtures of low molecular weight heparins used to
prevent blood clots and cover Aventis’s Lovenox product.

The district court had granted a motion for summary
judgment of unenforceability without holding a hearing and based on repeated
representations by Aventis of patentability based on the purported half-life
of the claimed products. The court
found Aventis at fault for comparing data based on different doses to show an
improved half-life when a comparison of available data using the same doses
actually showed that there was little if any difference between the half
lives of the prior art and the purported invention.

The Court found the omission by Aventis to meet the test
for materiality but held that based on the evidence before the District
Court, it was inappropriate to find an intent to deceive the USPTO on summary

The lower court’s decision was reversed and remanded
for further consideration.


A patent
challenger seeking summary judgment in relation to inequitable conduct will
do well to establish as far as possible an intent to deceive the USPTO.It will always be open to the patentee,
however, to challenge the motion by pointing to any one of a potentially
large number of remaining genuine issues of fact.

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