What happened

Summit Therapeutics (SMMT) traded around $18.65, up about 6.3%, as reported by StockAnalysis at 12:10 pm ET. The trigger was Sunday's updated survival data from a Phase III trial called HARMONi-2, where Summit's drug ivonescimab was tested directly against Merck's Keytruda.

Why it moved

Median overall survival came in at 30.8 months on ivonescimab versus 22.6 months on Keytruda — 8.2 months more — with a hazard ratio of 0.73 (95% CI 0.57–0.95, p=0.009) across 398 patients, 198 on each arm, per FiercePharma and Summit's release.

The hazard ratio is the story, so unpack it. A ratio of 0.73 means at any given point in the trial, a patient on ivonescimab was 27% less likely to die than one on Keytruda.

Here's what the headline skips. Most cancer drugs win approval by beating chemotherapy or a placebo. Very few are tested head-to-head against the reigning standard of care, because losing that fight kills the asset. Ivonescimab took the fight and won on overall survival — the endpoint that counts, not a surrogate like tumour shrinkage. In PD-L1-high patients the hazard ratio was 0.58, though Summit flags that as descriptive and not formally powered — the trial wasn't built to prove it.

The business

Summit is essentially a one-molecule company, which changes how you read today's move. Ivonescimab is a PD-1/VEGF bispecific antibody — one drug blocking two targets at once — that Summit in-licensed from China's Akeso for $500m upfront and up to $5bn in total value. Summit holds US and European rights; Akeso kept China, where the drug is already approved and where this trial ran. Summit books no product revenue and a net loss near $856m over the trailing twelve months. Nearly the entire equity value rides on this one asset clearing Western regulators.

Valuation

P/E: not applicable — no product revenue and negative earnings (EPS −1.12), so there's no multiple to quote and no 5-year P/E range to place it against. What's left is scale: market cap $14.88bn against a 52-week range of $12.07–$29.23, per StockAnalysis. For a named peer on the other side of the trade, Merck (MRK) trades on a P/E of 113.08 with a $357.54bn market cap and $66.57bn trailing revenue. One is priced on a drug earning money today; the other on a drug that still has to get approved.

Who it touches

• Merck — Keytruda brought in roughly $29.5bn in 2024, nearly half of Merck's total sales, with US patent protection running out in 2027, per BioPharma Dive. MRK rose 0.69% today, so the market isn't pricing an immediate hit.
• Akeso (HK: 9926) — keeps Chinese commercial rights plus milestone and royalty economics on Summit's territories.
• Rival PD-1/VEGF bispecific developers — a head-to-head win validates the mechanism itself, not just one company's version of it.

The one risk that flips this

HARMONi-2 ran entirely in China. The FDA has rejected this exact setup before: in February 2022 its Oncologic Drugs Advisory Committee voted 14–1 against sintilimab, a lung-cancer drug from Eli Lilly and Innovent, because the pivotal trial was China-only and the panel doubted it reflected US patients. Richard Pazdur, who runs the FDA's Oncology Center of Excellence, called single-country trials "a step backward." Strong data and a clean regulatory path are not the same thing.

What to watch

Two dated events sit ahead, both worth tracking on the calendar. A PDUFA date of 14 November 2026 on a separate application Summit filed in January 2026 from the HARMONi study — that's the FDA's target decision day. And HARMONi-3, the global trial pitting ivonescimab plus chemotherapy against Keytruda plus chemotherapy. That one is multiregional by design — the direct answer to the China-only objection. Today's pop was about evidence; approval is a separate question. Other big moves are on the movers page.

As of 12:10 pm ET, 14 September 2026. Sources: FiercePharma, Summit Therapeutics press release, StockAnalysis, BioPharma Dive, Applied Clinical Trials. For discussion and education only — not investment advice. Verify before acting.