Fed Circuit backs Eli Lilly in Apotex’s appeal over failed Alimta NDA
The US Court of Appeals for the Federal Circuit yesterday, December 21, upheld Eli Lilly’s success in barring the sale of a copycat version of cancer treatment Alimta (pemetrexed disodium).
The US pharmaceutical company owns US patent number 7,772,209, which was filed in 2001 and ultimately granted in 2010. The patent covers Alimta, an injectable drug used to treat some forms of mesothelioma and lung cancer.
Between 2001 and 2010, Eli Lilly amended its patent application to remove vague and dependent claims which were preventing the US Patent and Trademark Office from granting the patent.
In particular, an examiner found it to be improper to use a trading name such as “Alimta” to claim or describe a material or product. Eli Lilly, therefore, cancelled its dependent claims reciting “Alimta” and simultaneously replaced the words “an antifolate” with “pemetrexed disodium” to remove obviousness challenges.
The ‘209 patent is due to expire in May 2022, but Canadian pharmaceutical company Apotex submitted a new drug application (NDA) with the intention of marketing and selling its own generic version of Alimta before the patent’s expiry.
Apotex’s proposed treatment contained a different salt form to that of Alimta, which contains pemetrexed disodium.
In 2017, Eli Lilly alleged that Apotex’s NDA infringed the ‘209 patent in a complaint filed at the US District Court for the Southern District of Indiana.
In response, Apotex argued that prosecution history estoppel prevents Eli Lilly from alleging patent infringement by equivalents.
Prosecution history estoppel applies to prevent a party that filed a patent application and then made narrowing amendments to it from later invoking the doctrine of equivalents to broaden the scope of their claims, thereby expanding the protection of the patent.
Apotex argued that Eli Lilly’s amendments—cancelling its recitals of “Alimta” and adding the words “pemetrexed disodium”—had narrowed the patent’s claims, giving rise to prosecution history estoppel.
The court disagreed. It held that Eli Lilly had not narrowed the scope of its patent claims by changing the words in its application.
On appeal, Apotex claimed that the court had erred in its conclusion.
Yesterday, the Federal Circuit dismissed Apotex’s arguments, stating that “we do not find them persuasive”.
It held that the district court properly concluded that prosecution history estoppel does not bar Eli Lilly’s infringement claims under the doctrine of equivalents, because the amendments made to the patent application did not narrow the claims.
As such, the Federal Circuit agreed that Apotex’s generic version of Alimta cannot be approved by the US Food and Drug Administration until the expiry of the ‘209 patent.
