A federal judge in Delaware has ruled in favor of Exelixis in its Cabometyx patent fight with MSN Laboratories, effectively pushing the earliest generic entry out to 2030.
After a four-day bench trial in October 2023, the Delaware District Court has rejected (PDF) MSN’s challenge to a group of three Cabometyx “malate salt patents” that expire in January of 2030. The three patents are U.S. patents 11,091,439, 11,091,440, and 11,098,015.
Thanks to the favorable ruling, Exelixis’ stock price rose 8.6% during Tuesday’s trading. As Exelixis’ bread-and-butter therapy, the Cabometyx franchise brought in $816 million in sales, or 77% of the company’s total revenues, during the first half of 2024.
“Overall, we believe the verdict removes all uncertainties associated with Cabometyx’s U.S. market exclusivity, which has been a persistent overhang on Exelixis shares,” William Blair analysts wrote in a Tuesday note.
As a result, the William Blair team said Cabometyx’s U.S. market exclusivity is likely to be retained until 2030. Previously, Exelixis had settled with Teva and Cipla, granting the two generics makers licenses to market their Cabometyx copycats beginning on Jan. 1, 2031.
Separately, back in early 2023, the Delaware District Court had rebuffed MSN’s contest of the Cabometyx compound patent 7,579,473, which is slated to lose protection in August 2026. At that time, in a win for MSN, the court ruled that the Indian company’s proposed product does not step on Exelixis’ polymorph patent U.S. 8,877,776, which expires in October 2030.
The MSN candidate uses a different polymorphic form of cabozantinib-malate than is used in Cabometyx.
MSN challenged the three malate salt patents following an earlier stipulation that its proposed generic version would infringe on those Exelixis protections. The lawsuit was part of a process to determine whether MSN could launch in 2026 or several years later.
Besides those three patents, the Delaware court also ruled that Exelixis’ pharmaceutical composition patent 11,298,349, while valid, is not infringed by MSN’s drug. Had infringement been established there, MSN would have had to wait even longer, until February 2032, to introduce its copy in the U.S.
First approved by the FDA in 2016, Cabometyx and its twin brand Cometriq have been cleared to treat kidney cancer, liver cancer and thyroid cancer. The tyrosine kinase inhibitor is still on a growth trajectory, with first-half 2024 sales up 5.6% compared to the same period in 2023.
In addition to the drug's approved uses, Exelixis is pursuing expansion opportunities in neuroendocrine tumors (NETs) and prostate cancer.
In the phase 3 CABINET trial, Cabometyx showed stellar results in delaying the time before progression or death compared with placebo in patients with pancreatic NETs and in patients with extra-pancreatic NETs who had previously treated tumors. The FDA has accepted Exelixis’ application in the two NET categories and assigned a target decision date of April 3, 2025.
Cabometyx’s prospects in prostate cancer aren't as clear. The phase 3 CONTACT-02 trial met one of its dual primary endpoints, showing that Cabometyx and Roche’s Tecentriq significantly cut the risk of progression or death versus a change of novel hormonal therapy in patients with metastatic castration-resistant prostate cancer. But the combo didn’t mount a statistically significant benefit on the overall survival metric.
Nevertheless, Exelixis has announced a plan to submit an application to the FDA this year. Because the lack of a life-extension showing, Exelixis’ partner Ipsen has decided not to apply for the indication in EU.