Summit Therapeutics announced on November 15, 2026, that the US Food and Drug Administration issued a complete response letter for its ivonescimab application in previously treated lung cancer. According to the company’s statement, distributed by Business Wire, the application cannot be approved in its present form because the overall-survival evidence did not meet the agency’s requirements.
Why the FDA declined the application
Summit said the application covered ivonescimab combined with platinum-containing chemotherapy for locally advanced or metastatic non-small cell lung cancer after prior EGFR tyrosine kinase inhibitor therapy. The supporting HARMONi trial was a global, randomized, double-blind Phase III study with two primary endpoints: progression-free survival and overall survival.
The company reported that HARMONi met its progression-free survival endpoint, while the primary overall-survival analysis did not achieve statistical significance. Summit said the FDA considered the progression-free survival result insufficient to establish a positive benefit-risk profile without a statistically significant overall-survival improvement. Reuters and BioSpace independently reported the decision on November 15.
What a complete response letter means
The FDA’s explanation of complete response letters says the agency sends one when it determines that an application cannot be approved in its current form. The letter describes deficiencies identified during review and may recommend actions to obtain marketing approval.
That definition distinguishes an application decision from a final judgment on every possible use of a molecule. Summit’s statement says it intends to continue its wider ivonescimab development program.
What research offices should track
For universities and offices administering clinical research, the practical implication is to keep the trial results, the sponsor’s interpretation and the regulatory decision distinct. A useful record identifies the application and indication, the primary endpoint results and the current approval status separately.
For this application, an endpoint success did not resolve the regulator’s concern about the other primary endpoint. Research teams interpreting statistical significance or documenting clinical trial endpoint choices can use that distinction when discussing evidence with institutional partners. This is an implication for research administration, rather than a new regulatory requirement.
Sources
- Summit Therapeutics: Ivonescimab application update, Business Wire distribution. Published and checked 2026-11-15.
- Reuters: FDA declines Summit lung cancer drug. Published and checked 2026-11-15.
- BioSpace: Summit’s ivonescimab rejected by FDA. Published and checked 2026-11-15.
- FDA: Complete Response Letters. Checked 2026-11-15.
