A recent interim analysis in the Harmoni-3 trial for ivonescimab has resulted in significant turbulence for Summit Therapeutics, leading to a dramatic drop in the company’s share price. The trial, closely followed by investors and industry experts due to its innovative nature as a PD-1xVEGF bispecific, encountered a setback as the squamous cohort reportedly missed the statistical significance threshold for progression-free survival (PFS) in this latest evaluation.
Summit Therapeutics disclosed on Thursday that an independent data monitoring committee recommended the continuation of the trial in its original double-blind format, despite the interim results. This trial aims to assess the efficacy of ivonescimab when combined with chemotherapy versus the established treatment of Merck’s Keytruda in treating metastatic non-small cell lung cancer (NSCLC) as a first-line option.
Following the news, Summit’s stock saw a sharp decline of over 25% in early trading on Friday, prompting analysts to reassess the situation. The sudden drop illustrates the high expectations surrounding the Harmoni-3 trial, especially as the company had modified the trial’s design multiple times to enhance its prospects. Notably, earlier adjustments included the separation of squamous and nonsquamous patients into distinct cohorts and the introduction of an additional interim analysis of PFS in the second quarter for squamous patients.
The missed statistical significance, while disappointing, is not deemed catastrophic by all analysts. Summit emphasized in its latest press release that achieving statistical significance at this interim point involved a stringent threshold, allowing for an upcoming planned final PFS analysis to utilize the preserved alpha. Analysts at Citi noted that the low number of PFS events could be a factor contributing to this interim miss, although they also could not dismiss concerns about the magnitude of PFS improvement.
Comparatively, past trials conducted by Akeso, the original developer of ivonescimab, demonstrated more promising outcomes; both Harmoni-2 and Harmoni-6 met their PFS endpoints at interim analyses. Harmoni-6, specifically, showed that ivonescimab monotherapy outperformed Keytruda by a notable margin in terms of PFS for PD-L1-positive NSCLC cases.
As the Harmoni-3 trial encounters this hurdle, the upcoming presentation of Harmoni-6’s overall survival data at the prestigious American Society of Clinical Oncology (ASCO) annual meeting heightens the stakes for Summit. The plenary session’s positioning has generated enthusiasm among investors, with some analysts projecting that ivonescimab in combination with chemotherapy could offer substantial overall survival benefits.
However, the setback in the Harmoni-3 trial does raise concerns regarding the comparability of findings from Chinese trials to those seen in international studies. Analysts suggest that any deterioration in PFS benefits in the global trial could lessen its appeal as a treatment option. As the market eagerly anticipates the outcomes of further studies, the challenges faced by the Harmoni-3 trial underscore the complexities and uncertainties inherent in clinical research.
Investor sentiment remains cautiously optimistic yet vigilant, particularly as the results of ongoing analyses, including the final PFS and interim overall survival readouts expected in the latter half of 2026, will be critical in determining the future trajectory of Summit Therapeutics and its promising candidates.
