Exelixis' Zanzalintinib Combo Boosts Survival In Colorectal Cancer, Stock Soars

On Sunday, Exelixis, Inc. EXEL revealed topline results from the STELLAR-303 phase 3 pivotal trial of zanzalintinib (100 mg) combined with atezolizumab.

The study includes patients with previously treated non-microsatellite instability (MSI)-high metastatic colorectal cancer (CRC).

Zanzalintinib in combination with Roche Holdings AG RHHBY atezolizumab (Tecentriq) demonstrated a statistically significant improvement in overall survival (OS) versus Bayer AG BAYRY Stivarga (regorafenib).

Also Read: Exelixis Stock Soars As Analysts Applaud Raised 2025 Guidance, Q1 Earnings Beat

These topline findings are from the final analysis conducted by the Independent Data Monitoring Committee of one of the dual primary endpoints of the STELLAR-303 phase 3 trial.

The trial will proceed to the planned final analysis for the other dual primary endpoint of OS in patients without liver metastases (non-liver metastases, NLM).

The safety profiles of zanzalintinib in combination with atezolizumab and of regorafenib were generally consistent with what has been previously observed, and no new safety signals were identified.

Secondary endpoints of STELLAR-303 include progression-free survival, objective response rate and duration of response in the ITT population and in the NLM subgroup of patients. Exelixis plans to submit detailed results of STELLAR-303 for presentation at an upcoming medical conference.

Following this positive news, analysts at William Blair said that the announcement “represents the first pivotal success from the zanzalintinib program, and we are encouraged that the STELLAR-303 study met one of the dual primary endpoints of overall survival among the intent-to-treat population, representing the largest commercial opportunity (risk-adjusted U.S. peak sales of $875 million, according to our estimates).”

Management had earlier projected that zanzalintinib could reach $5 billion in U.S. net product sales by 2033, with 45% expected from genitourinary cancers, another 45% from gastrointestinal cancers, and the remaining 10% from head-and-neck cancers. Analyst Andy Hsieh asserted that the early positive results from the STELLAR-303 trial mark the first step toward reaching that target.

He added, “From a stock perspective, given its substantial and likely durable cash flow generation into early 2030, we continue to believe Exelixis provides investors with a highly defensive investment profile. We also believe that the strategic positioning outlined by Exelixis should drive moderate growth into the next decade.”

Adding to Exelixis’ recent positive developments, its partner Ipsen also recently achieved a regulatory milestone.

On Friday, Exelixis’ partner Ipsen received a positive opinion from the European Medicine Agency’s Committee for Medicinal Products for Human Use for Cabometyx (cabozantinib) for adult patients with unresectable or metastatic, well-differentiated extra-pancreatic and pancreatic neuroendocrine tumors who have progressed following at least one prior systemic therapy other than somatostatin analogs.

A regulatory decision by the European Medicines Agency is anticipated in 2025. In March 2025, the U.S. Food and Drug Administration approved Cabometyx in this setting.

Price Action: EXEL stock is trading higher by 11.1% to $44.85 at last check Monday.

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