Summit Therapeutics (Summit Therapeutics (SMMT)) on Wednesday shared updated overall survival data from its Phase 3 HARMONi study, and the numbers are looking better the longer you look. The trial is testing ivonescimab, an investigational bispecific antibody, combined with chemotherapy against a placebo-plus-chemo regimen for patients with a specific type of lung cancer.
The study focuses on people with EGFR-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who have already been treated with a third-generation EGFR tyrosine kinase inhibitor (TKI). Think of it as a tough-to-treat group where new options are desperately needed.
In the primary analysis from April 2025, patients getting ivonescimab plus chemo had a median overall survival of 16.8 months, compared to 14.0 months for the placebo group. That's a nearly three-month advantage, but at the time it didn't reach statistical significance — which is a bit like having a great lead in a race but not quite crossing the finish line with enough margin to declare victory.
But here's where it gets interesting: as the data matures, the trend keeps improving. By September 2025, extended monitoring of Western participants yielded a hazard ratio of 0.78. The most recent data cut in June 2026, with a median follow-up of 23.2 months for Western patients, showed an even stronger hazard ratio of 0.76. A hazard ratio below 1 means the treatment is reducing the risk of death, and lower is better. So the signal is getting clearer over time.
What's particularly encouraging is that the survival benefits for Western patients now align with what was seen earlier in Asian patients, who had longer follow-up periods. That consistency across different populations is a big deal — it suggests the drug's effect is real and not just a fluke in one group.
On the safety front, ivonescimab maintained a manageable profile with no new adverse signals detected. That's always good news, especially for a drug that's already shown promise.
Summit has shared these updated findings with the FDA to support its Biologics License Application. The agency has set a target action date of November 14, 2026, to decide on the drug's approval. That's a date investors will be watching closely.
As for the stock, Summit Therapeutics shares were up 2.26% at $14.96 on Wednesday, reflecting cautious optimism. The market seems to be pricing in the improving data, but the real catalyst will be the FDA's decision later this year.
