Apotex challenged the validity of the '265 patent on the grounds of anticipation and obviousness — namely that the structure and composition of the drug was described in a previous patent, and that separating the enantiomers would be obvious — and that the patent was also unenforceable as Sanofi allegedly made false statements when applying for the patent. The court disagreed on all these accounts, finding Apotex's arguments “ultimately unpersuasive”. Although the chemical structure of clopidogrel fell into the broad claims described in an earlier patent covering thienopyridine compounds, the structures described in this prior art contained two variable substituent groups, and the court held that a person would need to engage in “impermissible mechanistic dissection and recombination” to arrive at the structure of clopidogrel. In addition, the court found that the prior art patent did not teach the composition of clopidogrel bisulphate, as there was no correlation between the use of a particular acid to form a particular salt of a particular enantiomer. Whether one could predict that the properties of a single enantiomer would be superior to the opposite enantiomer was hotly contested by both parties in this case. The court held that prior art did not predict that one enantiomer would have all the activity and none of the toxicity, and that separating the enantiomers would not have been obvious — indeed Sanofi spent 4 years and millions of dollars before deciding to do this. Concluding, the court decided that clopidogrel bisulphate as a whole (that is, the chemical and salt) has unexpected properties that make it non-obvious, and therefore patentable.
In ruling, the court granted a permanent injunction that prevents Apotex from engaging in any activity that infringes the '256 patent. Apotex said it will appeal in the higher courts, adding that the Supreme Court's recent decision on the Court of Appeals definition of obviousness (KSR International versus Teleflex et al.; Nature Rev. Drug Disc. 6, 426; 2007) could affect the decision of this case in a positive way for them. Whether this decision is upheld remains to be seen, but as highlighted below, even with a new more flexible outlook on obviousness, the Court of Appeals is not simply overturning every such case that comes its way.
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