The strange position of ivonescimab after this week's lung cancer conference is that the strongest evidence for the drug does not come from the trial the FDA will vote on.
At WCLC 2026 in Seoul, Summit Therapeutics presented updated overall survival data from HARMONi, its global Phase III trial of ivonescimab plus chemotherapy against placebo plus chemotherapy in patients whose EGFR-mutated lung cancer had progressed after a third-generation EGFR inhibitor. Across the full 438-patient trial, the hazard ratio for survival improved to 0.76, with a nominal p-value of 0.0151 and median overall survival of 16.8 months versus 14.0 months. In the 165-patient Western subgroup, median survival was 17.5 versus 14.0 months, a hazard ratio of 0.76 whose confidence interval, 0.52 to 1.10, still crosses 1.0.
Those numbers matter because of what came before. The trial's April 2025 primary analysis produced a hazard ratio of 0.79 that narrowly missed statistical significance, with a p-value of 0.057 against the trial's alpha threshold. The September 2025 cut improved to 0.78, and the June 2026 cut to 0.76. The trend has pointed in the right direction for eighteen months. It has not yet produced a statistically significant, alpha-controlled overall survival result in the global trial, and the company's own release labels the latest p-value nominal.
The China trial that did everything right
Partner Akeso presented HARMONi-2, its own registrational Phase III conducted entirely in China, on the same day. In 398 patients with previously untreated advanced lung cancer expressing PD-L1, ivonescimab monotherapy produced median overall survival of 30.8 months against 22.6 months for pembrolizumab, a hazard ratio of 0.73 with a p-value of 0.009 that met the trial's prespecified statistical bar. At 36 months, 45.0 percent of ivonescimab patients were alive versus 33.1 percent on pembrolizumab. The earlier progression-free survival result, a hazard ratio of 0.51, supported the drug's approval in China in April 2025, and Akeso describes the combination of results as the first randomized, double-blind Phase III to show statistically significant survival and progression advantages over pembrolizumab.
Ivonescimab is a bispecific antibody that blocks both PD-1 and VEGF, engineered by Akeso and licensed to Summit for North America, Europe and other territories. The design makes it the rare checkpoint drug with an anti-angiogenic mechanism that does not require combining two separate medicines. Safety data from both presentations showed no new signals, and in HARMONi-2, serious treatment-related adverse events ran higher on the ivonescimab arm, 29.9 percent versus 21.6 percent, though treatment-related deaths were lower.
The approval question
The FDA accepted Summit's biologics license application in January, with a goal action date of November 14, 2026, seeking approval of ivonescimab plus chemotherapy for EGFR-mutated lung cancer after a third-generation inhibitor. Summit has submitted the June 2026 analysis to the agency. The company has fast track designation for the setting but no FDA breakthrough designation, and it has zero revenue, about $690 million in cash and roughly $140 million in quarterly operating cash use as it builds a U.S. launch organization.
The regulatory debate is unusually concrete. Some analysts, including Leerink's Daina Graybosch, argue the FDA will not approve on non-significant overall survival, and UBS puts approval odds low while allowing for a positive surprise. The counterargument is precedent: every drug previously approved in this exact setting reached approval without statistically significant overall survival in its registrational trial. The distinguishing feature of the current review is the agency's stated hard line on survival benefit in oncology, which makes the HARMONi numbers a genuine test.
What the skeptics actually say
The fair version of the skeptical case is not that the drug failed. It is that the global trial's statistical plan was complicated enough to consume its own headroom. Multiple primary endpoints and repeated looks draw down alpha, and the June 2026 analysis is explicitly nominal. Independent clinicians have also flagged the follow-up imbalance between the trial's Asian cohort, with a median follow-up of 32.7 months, and the Western cohort at 23.2 months, a gap the company's own chief medical officer conceded on a prior call by saying the company "knew this was going to be a problem."
The company's response is that the survival trend has been consistent in every cut, that the Western hazard ratio has improved from 0.98 to 0.76 as data matured, and that the first-line program, HARMONi-3, will deliver more definitive data, with final progression-free survival results expected in the second half of this year. What neither side disputes is that the drug now has a mature, statistically significant survival result in one setting, first-line PD-L1-positive disease, and a suggestive but not conclusive one in another. The geography of that distinction, China on one side and the FDA filing on the other, is the uncomfortable center of the November decision.
Primary sources
- Summit Therapeutics press release filed with SEC Form 8-K, September 15, 2026, for the HARMONi updated survival data and the HARMONi-2 presentation details.
- Akeso Bio, WCLC 2026 presentation releases, for the HARMONi-2 overall survival results and subgroup analyses.
- SEC filing, January 2026, for the BLA acceptance and November 14, 2026 PDUFA date.
- BioPharma Dive, prior WCLC coverage of the September 2025 data, for the Western-subgroup skepticism and analyst positions cited as background.