Exelixis, Inc. (NASDAQ:EXEL) disclosed in a September 11 filing that the FDA had extended the review of zanzalintinib by three months, setting a new target action date of March 3, 2027. The September 10 notification followed an FDA request for updated safety and efficacy information. The submitted data were classified as a major amendment.
The application seeks approval of zanzalintinib plus atezolizumab for metastatic colorectal cancer following fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy and, for RAS wild-type disease, anti-EGFR therapy. The extension leaves approval unresolved. For Exelixis, Inc., the investment question is whether the complete evidence package supports a favorable benefit-risk assessment and a commercially useful indication.
Bull Case
The strongest evidence remains the positive overall-survival result in the full STELLAR-303 study population. This randomized Phase 3 trial evaluated the combination against regorafenib in previously treated metastatic colorectal cancer that was not microsatellite instability-high.
In the intention-to-treat population, which included all randomized patients regardless of active liver metastases, median overall survival was 10.9 months with the combination versus 9.4 months with regorafenib. The hazard ratio was 0.80, and the difference was statistically significant. That gives Exelixis, Inc. a demonstrated survival benefit against an active comparator.
The full-population result matters because the application rests on more than an isolated exploratory finding. It met one of the trial’s two prespecified primary endpoints, providing a substantive clinical basis for regulatory review.
Updated safety and efficacy information can help regulators assess the treatment’s benefits and risks more fully. The commercial opportunity would become clearer with an approval decision specifying eligible patients and prescribing requirements. If approved, the combination could give Exelixis, Inc. another source of oncology revenue, subject to physician adoption and reimbursement.
Bear Case
The separate co-primary endpoint in patients without active liver metastases did not reach statistical significance. In the June 2026 final analysis, median survival was 15.9 months with the combination versus 12.7 months with regorafenib, but the hazard ratio of 0.83 had a 95% confidence interval of 0.66 to 1.05.
That numerical advantage does not establish a statistically significant benefit in the subgroup. Because this was a prespecified co-primary analysis, the result deserves attention when evaluating the overall evidence package. The September filing does not identify the subgroup outcome as the reason for the extension.
Treatment burden is another consideration. Previously reported Grade 3 or 4 treatment-related adverse events occurred in 59% of patients receiving the combination versus 37% receiving regorafenib. The FDA must weigh the survival benefit alongside tolerability, while physicians would make similar judgments if the treatment becomes available.
The timing change also postpones the expected regulatory decision and could defer a potential launch and revenue contribution. Exelixis, Inc. has not disclosed the updated results in the September filing, so investors cannot yet determine whether the amendment strengthens or complicates the application.
Hedge Fund Sentiment
The filings available so far reflect positions held before Exelixis, Inc. reported the zanzalintinib review extension. Insider Monkey’s database showed 47 hedge funds holding Exelixis, Inc. at the end of 2Q2026, up from 41 funds three months earlier.
Conclusion
Exelixis, Inc. retains a credible approval case built on the full-population survival benefit. The unsuccessful subgroup endpoint and treatment burden remain relevant, while the extension itself establishes additional review time. Updated evidence, the FDA’s benefit-risk assessment, and any eventual label will determine approval prospects and commercialization timing.
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This article is originally published at Insider Monkey.
