New York, May 20, 2026, 13:04 (EDT)
- Exelixis shares rose about 2.5% in Wednesday afternoon trading, outpacing the iShares Nasdaq Biotechnology ETF but lagging the SPDR S&P Biotech ETF.
- The company said Merck will supply Keytruda Qlex for Exelixis’ planned late-stage STELLAR-316 colorectal cancer trial.
- Investors are also watching a December 3 FDA target date for another zanzalintinib filing and Exelixis’ new $750 million buyback plan.
Exelixis shares rose on Wednesday as investors weighed a fresh Merck collaboration that pushes the biotech company’s next cancer-drug program deeper into late-stage testing.
The stock was up 2.5% at $49.89 in afternoon trading, giving the Alameda, California-based company a market value of about $13.3 billion. The broader biotech tape was also firm: the iShares Nasdaq Biotechnology ETF rose 1.8%, while the SPDR S&P Biotech ETF gained 3.8%.
The timing matters because Exelixis is trying to show that it can build beyond Cabometyx, its main cancer medicine, while keeping shareholders close with buybacks and near-term regulatory events. Its next big test is zanzalintinib, an oral kinase inhibitor, meaning a drug designed to block enzymes that help cancer cells grow and spread.
Exelixis said on Tuesday that Merck will supply Keytruda Qlex, a subcutaneous version of its anti-PD-1 immunotherapy, for STELLAR-316. The trial is planned as a phase 3 pivotal study, a late-stage trial often used to support regulatory approval, in patients with resected stage II/III colorectal cancer.
The study will test zanzalintinib with and without Keytruda Qlex in patients who are MRD-positive, short for molecular residual disease — traces of cancer DNA that can remain after treatment even when scans show no disease. The main goal is disease-free survival, or how long patients live without the cancer returning.
Dana T. Aftab, Exelixis’ head of research and development, called the Merck tie-up “continued progress” for zanzalintinib and said the company wants to “prevent or delay metastatic progression.” Exelixis expects to start STELLAR-316 in mid-2026. Exelixis, Inc.
The Merck agreement builds on Exelixis’ January collaboration with Natera, whose Signatera test will be used to find MRD-positive patients for enrollment. Natera executive John Simmons said the assay could help “identify high-risk patients earlier,” while Aftab said the trial could make zanzalintinib the first MRD-guided treatment for this group if it succeeds. Natera Investor Relations
There is competitive weight here, but not in a clean rival-versus-rival way. Merck is supplying the immunotherapy for the trial, Natera is providing the test, and Exelixis is sponsoring the study. In a separate colorectal cancer program, Exelixis’ zanzalintinib plus Roche’s atezolizumab was tested against regorafenib, a Bayer drug, in the STELLAR-303 phase 3 trial.
That earlier filing remains a nearer-term catalyst. Exelixis said the U.S. Food and Drug Administration accepted its new drug application for zanzalintinib plus atezolizumab in previously treated metastatic colorectal cancer and set a December 3, 2026 target action date. The company said its 2026 revenue forecast does not include any sales from a possible approval.
The company’s latest quarter gives the shares some support. Exelixis reported first-quarter revenue of $610.8 million, up from $555.4 million a year earlier, with U.S. cabozantinib franchise net product revenue of $555.0 million. Non-GAAP earnings were 87 cents per diluted share; non-GAAP means adjusted earnings that exclude some items such as stock-based compensation.
Buybacks are part of the equity story. A May 5 filing showed Exelixis’ board authorized up to $750 million in additional share repurchases through December 31, 2027, after the company said it had already retired 86.8 million shares since March 2023.
There was also routine insider activity near the recent highs. A Form 4 filed Tuesday showed Chief Financial Officer Christopher Senner sold 34,901 shares on May 18 at a weighted average price of $50, after a separate tax-withholding transaction tied to restricted stock units. The filing showed he directly held 952,317 shares after the sale.
But the risk is straightforward. STELLAR-316 has not started, late-stage oncology trials can miss their goals, and the December FDA decision on zanzalintinib is not assured. Exelixis also warned that trial timing, safety signals, partner performance and possible competition, including generic threats to marketed products, could shift its outlook.
