Novartis on the hook for $178M after losing Tafinlar patent fight with Daiichi's Plexxikon business

A Northern California jury ruled in favor of Daiichi Sankyo’s Plexxikon Inc., finding that Novartis infringed on two patents for a skin cancer drug. The jury awarded Plexxikon $177.8 million, but Novartis could be on the hook for much more.

The case, which was filed four years ago, surrounded the development of Plexxikon’s melanoma treatment Zelboraf and GlaxoSmithKline’s melanoma therapy Tafinlar. In 2015, GSK traded the drug, along with other cancer assets, to Novartis. 

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“We are delighted by the jury verdict and the vindication of Plexxikon’s groundbreaking work developing new therapies for cancer patients,” Daralyn Durie, Plexxikon's attorney, said in an email

According to Durie, Plexxikon will receive royalty payments for future sales of Tafinlar. Additionally, because the jury found that the infringement was “willful,” the award could be increased up to threefold.  

A Novartis spokesperson said in an email that the company is considering options, including an appeal, "but otherwise can't comment on ongoing litigation."

Plexxikon argued that more than a decade ago, GSK scientists acquired knowledge to develop Tafinlar after consulting with Plexxikon in potential partnership talks, which never materialized into a deal. 

“Evidence came in at trial that the GSK inventor had looked at Plexxikon patent applications disclosing the core structure of the molecule before shifting the program focus in a way that ultimately led to the infringement,” Durie wrote. 

Novartis had challenged the validity of the patents, contending that GSK was first with the invention.

Plexxikon filed for its patents in 2005 and won approval for Zelboraf in 2011. Roche secured marketing rights to the drug in 2006. GSK applied for its patents on Tafinlar in 2008 and captured a 2013 approval. 

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Once it reached the market, Tafinlar quickly overtook Zelboraf. By 2016, for example, when Zelboraf registered sales of $218 million, Tafinlar earned $672 million. Last year, as a combination treatment with another Novartis drug, Mekinist, Tafinlar rang up sales of more than $1.5 million.

Zelboraf and Tafinlar inhibit the growth of cancer cells that have a mutated form of the BRAF gene. According to the original complaint, Plexxikon’s patents were for a class of "BRAF kinase inhibitors which selectively bind to the BRAF kinase that results from the V600E mutation.” 

“Genus patents—like those in the lawsuit—are routinely used to prevent competitors from knocking off our scientific innovations with slight molecular changes," said Plexxikon CEO Chao Zhang in a release. "We are gratified that the jury upheld their validity, protecting our investment.”