Akeso reports an OS benefit for ivonescimab over pembrolizumab in PD-L1-positive NSCLC

A preplanned analysis of a secondary endpoint, announced without figures

Overall survival was a secondary endpoint in HARMONi-2, and the analysis was preplanned rather than post-hoc. That distinction matters for how the statistical claim should be read, since an analysis specified in advance is held to the protocol’s own terms rather than chosen after the data were seen.

What Summit’s release does not carry is any number. There is no hazard ratio, no median overall survival for either group, no confidence interval and no follow-up time. Whether the survival difference is a matter of weeks or of many months cannot be established from what has been released, and the size of an effect is what determines its clinical weight. The release states that the results are scheduled for presentation at an upcoming medical conference, and does not name it.

The primary progression-free survival analysis gave a hazard ratio of 0.51

The primary analysis of HARMONi-2 reported a statistically significant improvement in progression-free survival by independent radiologic review committee, with a hazard ratio of 0.51 (95% CI 0.38 to 0.69). Those results were published in The Lancet in 2025 (Xiong A, Wang L, Chen J, et al. 2025;405:839-849). Ivonescimab was first approved in China in May 2024, and China’s National Medical Products Administration granted marketing authorisation on the basis of HARMONi-2 in April 2025.

A progression-free survival result does not establish a survival benefit, which is the reason a preplanned overall survival analysis is reported separately at all. What the release states about that analysis is its direction and its statistical significance, and nothing about its magnitude.

A single-region trial, with the drug still investigational outside China

HARMONi-2 was conducted entirely in China, and the release states that Akeso exclusively generated, managed and analysed all the relevant data. Summit Therapeutics is running HARMONi-7, a phase III trial of ivonescimab monotherapy against pembrolizumab monotherapy in first-line metastatic NSCLC with high PD-L1 expression, which puts a similar comparison to a separate patient population.

Ivonescimab is a bispecific antibody that blocks PD-1 and VEGF in a single molecule. It is approved and commercially available in China for indications in NSCLC, and it has no regulatory approval in the United States or Europe.