Exelixis on Thursday said a combination of its cancer drug Cabometyx and Roche’s immunotherapy Tecentriq failed a Phase 3 trial testing it in patients with advanced kidney tumors, closing off an opportunity to further expand the drug’s use before a key patent expires.
The trial is one of three combination studies Exelixis has been running in the hopes its drug could carve out a new niche in clinical practice — helping patients who’d previously progressed after receiving an immunotherapy. Two of those efforts have now failed. In December, a Cabometyx-Tecentriq regimen came up short in a trial in patients with non-small cell lung cancer who had progressed following treatment with immunotherapy and chemotherapy.
One more Phase 3 trial in prostate cancer is expected to produce results later this year. In a Thursday note to clients, Stifel analyst Stephen Willey cast doubt on on its prospects, noting that physicians he’s spoken with were skeptical of Exelixis’ earlier study results and trial design.
The study Exelixis reported Thursday tested the Cabometyx-Tecentriq combination against Cabometyx alone in patients who had progressed on a type of immunotherapy known as a checkpoint inhibitor. The combination didn’t hold tumors in check longer than Cabometyx alone, missing the study’s primary goal.
Cabometyx is still well-established in kidney cancer, as it’s cleared for use in the first-line setting alongside Opdivo as well as broadly for advanced disease. It’s also marketed as a second-line treatment in liver and thyroid cancers. Between commercial sales and revenue from its collaboration with Ipsen, Cabometyx brought in $1.4 billion for Exelixis in 2022.
As an aging drug, however, Cabometyx could face generic competition in the coming years. Its main “composition of matter” patent is due to expire in 2026, although other parts of its intellectual property estate could extend exclusivity out to 2033.
More competition could come from Merck & Co., too. The pharmaceutical giant has a drug called belzutifan in two Phase 3 trials in kidney cancer, including a head-to-head study against Cabometyx in the second-line setting. Success in those studies could erode Exelixis’ revenue in the future, Willey wrote.
Exelixis is responding by advancing a newer experimental drug called zanzalintinib. The biotech began Phase 3 trials of that drug in kidney and colorectal cancer last year.