Eisai says patent win blocks Lenvima generic to 2036

Eisai has won a patent infringement lawsuit brought against Shilpa Medicare that sought to prevent the Indian generic drugmaker from launching a version of its MSD-partnered cancer drug Lenvima in the US.

The verdict of the US district court in New Jersey is that Shilpa's generic infringes a US patent on multikinase inhibitor Lenvima (lenvatinib), namely No. 11,186,547, which covers pure forms of lenvatinib mesylate. As a result, Eisai claims Shilpa will be blocked from getting FDA approval for its generic until it expires in February 2036.

The lawsuit also claimed infringement of another patent (No. 10,407,393), but the validity of that one was not upheld by the court.

Lenvima is a big earner for both Eisai and MSD, known as Merck & Co in the US and Canada, which licensed rights to the drug in 2018 in a near-$6 billion deal aimed at developing it as a partner drug to its blockbuster cancer immunotherapy Keytruda (pembrolizumab).

Last year, MSD reported more than $1 billion in alliance revenues from Lenvima, which is used alongside Keytruda in a widely used first-line therapy for kidney cancer and as a second-line treatment for some forms of endometrial cancer. The drug is also approved by the FDA for use on its own in thyroid, kidney, and liver cancers.

Eisai, meanwhile, reported JPY 328.5 billion (approximately $2.26 billion) in global sales of the drug in its last financial year ended 31st March, of which $1.51 billion came from the US market. The drug. which has been given to more than half a million patients worldwide since its launch 10 years ago, is also being developed in different combinations for kidney cancer and with Keytruda for oesophageal and liver cancers.

In a statement on the patent lawsuit victory – which Shilpa can appeal – Eisai said the verdict is "a major step forward in maximising the value of Lenvima for patients based on the intellectual property of the company."

Last year, Eisai reached a settlement agreement with Sun Pharmaceutical, which had also filed for approval of a Lenvima generic and was named in the New Jersey lawsuit. Under the terms of that agreement, Sun will not launch its generic before 1st July 2030, unless Eisai's patent protection is overturned in other lawsuits.

The Japanese pharma group has also sued two other generic manufacturers, Dr Reddy's Laboratories and Torrent Pharma, seeking to block the launch of their lenvatinib products.