Summit Therapeutics shares rise after partner reports positive Phase III cancer trial results

Summit Therapeutics Inc. (NASDAQ:SMMT) shares climbed 7.75% on Wednesday after partner Akeso Inc. reported positive topline results from a Phase III study evaluating ivonescimab in advanced biliary tract cancer.

Akeso said the HARMONi-GI1 trial achieved its primary endpoint, with ivonescimab combined with chemotherapy demonstrating statistically significant superiority in overall survival compared with durvalumab plus chemotherapy when used as a first-line treatment.

The study also met its key secondary endpoints covering progression-free survival and objective response rate.

HARMONi-GI1 study evaluates 682 patients

The Phase III trial enrolled 682 patients in China, where ivonescimab is already approved for certain non-small cell lung cancer indications.

However, the drug remains investigational and has not been approved in Summit’s licensed territories, which include the United States and Europe.

Detailed findings from HARMONi-GI1 are expected to be presented at an upcoming medical congress, potentially providing investors with greater clarity on the magnitude of the survival benefit observed in the trial.

H.C. Wainwright remains cautious on Summit

Despite the positive topline outcome, H.C. Wainwright analyst Mitchell S. Kapoor maintained a Neutral rating on Summit Therapeutics, noting that additional data will be required to assess the clinical significance of the results.

“We believe that establishes activity in Chinese BTC, but without the OS HR we cannot tell whether ivonescimab adds a modest survival benefit or materially improves on durvalumab. Summit has not disclosed a global BTC study; we assign no ex-China BTC economics. Per our current visibility, the next stock-moving item is likely to be HARMONi-3 final PFS/interim OS in 2H26. We reiterate our Neutral rating without a price target,” Kapoor commented.

His assessment suggests that the overall survival hazard ratio will be particularly important in determining whether ivonescimab offers a meaningful improvement over the existing treatment approach.

Guggenheim sees positive implications for lung cancer programme

Guggenheim analyst Brad Canino took a more optimistic view, reiterating a Buy rating on Summit Therapeutics with a $38.00 price target.

“We think this BTC result adds to the consistency of effect that should add weight to the argument that the China 1L lung cancer results are reproducible and generalizable. BTC is a relatively small market, so at SMMT’s valuation, we think the lung read-through is more important than the new unlocked BTC commercial opportunity,” Canino commented.

The analyst therefore sees the results as potentially significant beyond the biliary tract cancer opportunity, particularly if they strengthen confidence in ivonescimab’s performance across other tumour types.

With detailed HARMONi-GI1 data still to come and further HARMONi-3 results expected in the second half of 2026, investors are likely to remain focused on whether ivonescimab can demonstrate consistent clinical benefits across Summit’s broader oncology development programme.

Summit Therapeutics stock price