Federal judge upholds Cabometyx patent in Exelixis’ generic battle

A federal judge upheld a key patent on Exelixis’ cancer drug Cabometyx on Thursday, dealing a blow to MSN Laboratories’ potential generic version.

Exelixis filed suit against MSN back in 2019, after the latter company submitted an abbreviated new drug application (ANDA) for its Cabometyx generic. If MSN’s drug wins approval, Exelixis argued in the initial complaint that it would infringe on at least one or two claims of a patent dubbed ‘776, which expires in 2030, according to the FDA’s Orange Book.

The companies disputed the validity of that patent, and another called ‘473, which expires in 2026.

On Thursday, US Judge Richard Andrews upheld the ‘473 patent, determining that “MSN has not shown by clear and convincing evidence that claim 5 of the ‘473 patent is invalid as obvious.”

However, he also concluded that Exelixis failed to prove that MSN will infringe on the first claim of the ‘776 patent if its generic version is approved.

The ‘776 patent focuses on a specific crystalline form of cabozantinib (L)-malate called Form N-2. While MSN argues that its generic includes a different form, called Form S, Exelixis alleged that Form S is unstable and converts to N-2 over time, thus infringing upon the patent. However, Andrews determined that Exelixis “failed to prove by a preponderance of the evidence” that such would be the case.

Jeffrey Hessekiel

“While we are disappointed with the court’s decision concerning infringement of the ’776 patent, we remain confident in the strength of the cabozantinib patent estate,” Jeffrey Hessekiel, Exelixis’ general counsel and secretary, said in a news release. “We will continue to vigorously defend our intellectual property, safeguarding the scientific innovation that drives Exelixis’ ability to continue to discover, develop and ultimately bring new medicines to patients with difficult-to-treat cancers.”

Cabometyx was first approved in 2016 for patients with advanced renal cell carcinoma, and the TKI inhibitor has since racked up a slate of approvals in liver and thyroid cancer. Last year, the drug earned Exelixis just over $1 billion. Exelixis has been pushing for new indications including in combination therapies, such as with Roche’s Tecentriq. However, the Tecentriq combo failed a trial in patients with metastatic non-small cell lung cancer last month.

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