Why Summit Therapeutics Inc. (SMMT) Stock Rose 5.0% on Sep 14, 2026
The clearest new catalyst: Updated HARMONi-2 overall-survival data (Sep 13).
Why did SMMT stock rise?
Summit Therapeutics rose 4.96% to $18.42 on Monday, September 14, 2026 after partner Akeso reported (on September 13) updated overall-survival data from the Phase III HARMONi-2 trial of ivonescimab in PD-L1-positive NSCLC. The Akeso-sponsored, China-conducted readout reinforced the clinical case for ivonescimab, Summit's lead drug, and the stock rose against a down market. (The separate FDA PDUFA date on November 14, 2026 is for a different application, based on the global HARMONi trial.)
- Updated HARMONi-2 overall-survival data (Sep 13): On September 13, Akeso reported updated overall-survival results from the Phase III HARMONi-2 trial of ivonescimab in PD-L1-positive non-small cell lung cancer — an Akeso-sponsored study conducted in China. The data (an update, not the first positive OS readout) added to the growing clinical validation of ivonescimab and drove Summit's September 14 gain.
- Ivonescimab and the Akeso partnership: Ivonescimab is Summit's lead asset, licensed from Akeso: Summit operates under a collaboration and license agreement with rights to develop and commercialize ivonescimab in the U.S., Canada, Europe, Japan, Latin America, the Middle East and Africa, while Akeso retains the remaining territories, including China.
- Distinct from the November PDUFA: The move should not be conflated with Summit's upcoming FDA milestone: the November 14, 2026 action date is for ivonescimab plus chemotherapy in EGFR-mutated, locally advanced/metastatic non-squamous NSCLC (after third-generation EGFR-TKI therapy), and that application is based on the global Phase III HARMONi trial — a different study from the HARMONi-2 data released on September 13.
How the story developed
- September 13, 2026Akeso reports updated HARMONi-2 overall-survival data for ivonescimab in PD-L1-positive NSCLC.
- September 14, 2026SMMT closes up 4.96% at $18.42 on the readout, even as the broad market falls.
- November 14, 2026FDA action date (PDUFA) for ivonescimab + chemotherapy in EGFR-mutated NSCLC, based on the separate global HARMONi trial.
What it could mean for SMMT investors
The constructive case
- Updated positive overall-survival data strengthens the clinical case for ivonescimab, Summit's lead asset, ahead of key regulatory milestones.
- The stock rose against a falling market, showing the data was a genuine, idiosyncratic positive.
The cautious case & what could invalidate it
- Summit is still clinical/pre-approval, so the story hinges on regulatory outcomes — including the November HARMONi-based PDUFA, a different trial from the HARMONi-2 data that moved the stock.
- The HARMONi-2 readout was an update rather than a first pivotal result, so the incremental new information is smaller than a headline data drop.
- After a strong run, the shares are priced for clinical and regulatory success, leaving little room for a setback.
Initial detection
BestStocks first flagged SMMT intraday on Sep 14, 2026; this analysis was finalized after the close using the confirmed +5.0% session move and additional catalyst research.
Show the initial intraday note
Summit Therapeutics Inc. (SMMT) rose 4.96% to close at $18.42 on Monday, September 14, 2026 after its partner Akeso, on September 13, reported updated overall-survival data from the Phase III HARMONi-2 trial of ivonescimab in PD-L1-positive non-small cell lung cancer. The readout — from an Akeso-sponsored study conducted in China — added to the clinical validation of ivonescimab, Summit's lead drug, and the stock rose even as the broad market fell.
What to watch next: The bigger regulatory milestone is separate: the FDA has a November 14, 2026 action date for ivonescimab plus chemotherapy in EGFR-mutated NSCLC (after third-generation EGFR-TKI therapy), based on the global HARMONi trial — not HARMONi-2. Watch that PDUFA decision, further HARMONi/HARMONi-2 data, and Akeso-partnership updates; the stock is priced for clinical and regulatory success.
Frequently asked questions
Why did Summit Therapeutics Inc. (SMMT) stock rise on Sep 14, 2026?
Summit Therapeutics rose 4.96% to $18.42 on Monday, September 14, 2026 after partner Akeso reported (on September 13) updated overall-survival data from the Phase III HARMONi-2 trial of ivonescimab in PD-L1-positive NSCLC. The Akeso-sponsored, China-conducted readout reinforced the clinical case for ivonescimab, Summit's lead drug, and the stock rose against a down market. (The separate FDA PDUFA date on November 14, 2026 is for a different application, based on the global HARMONi trial.)
How much did SMMT stock rise on Sep 14, 2026?
SMMT rose 5.0% during the Sep 14, 2026 trading session.
What were the main drivers behind SMMT's move?
Updated HARMONi-2 overall-survival data (Sep 13); Ivonescimab and the Akeso partnership; Distinct from the November PDUFA.