U.S. mid-cap biopharmaceuticals: Summit Therapeutics Inc.: industry summit: HARMONI6 research and ASCO annual meeting outlook, the benchmark judgment is that the trend of overall survival has not reached statistical significance.

Jeffrey Walch+1 917 344 8613jeffrey.walch@bernsteinsg.comYi Zhao+1 917 344 8324 US SMID-Cap Biopharmaceuticals Summit Therapeutics Inc. Rating yi.zhao@bernsteinsg.com Underperform Price Target 7.70 USD SMMT Summit: Counting down to the HARMONI6 ASCO plenary, ourbase case is non-statistically significant OS trend Investment Implications Close Date21 May 2026SMMT Close Price (USD)17.47Price Target (USD)7.70Upside/(Downside)(56)%52-Week Range30.98/13.83SPX7,473.47FYEDecDiv YieldNAMarket Cap (USD) (M)13,040EV (USD) (M)12,347 We maintain an Underperform rating on SMMT. We recommend investors exit positions or,if possible, initiate short positions. In our opinion the long-term outlook for the company isnot on solid footing. Both SMMT and BioNTech have aggressively jumped into the misguided(based on our analysis) PD-L/VEGF bispecific experiment. This strategy could prove evenmore costly for SMMT than BioNTech because ivonescimab is their only drug in development. We expect the key end-points for all three of SMMT’s ongoing Ph3 trials to read-out non-statistically significant: overall survival for HARMONi-3/-7 in NSCLC and PFS for HARMONi-GI3 in MSS colorectal cancer. There is an expansive history of failed registrational trialsinvestigating the combination of anti-PD-1+ anti-VEGF across tumor types. We discount thenarrative that “this time it’s different” for anti-PD-1+VEGF as lacking in supportive clinicaldata. Instead, we initiate with an Underperform rating because the science and clinical data We rate SMMT Underperform with PT $7.70 (-56%) based on our DCF valuation. DETAILS Key messages: 1. We expect HARMONi6’s ASCO presentation to show non-statistically significant overall survival at interim analysis: OS trendHR >0.722 is likely in the absence of a pre-conference press release. 2. HARMONi's pending FDA decision is a false catalyst: Toss-up for approval in a competitive patient population with lowerrevenue upside. 3. The odds are stacked against HARMONi3 & HARMONi7: Historically, adding anti-VEGF to immunotherapy led toencouraging PFS but failed to achieve statistically significant overall survival required in 1L NSCLC. 4. Ivonescimab's CRC Ph3 trial is unlikely to be successful: SMMT's single arm preliminary data fails to demonstrate thataddition of anti-PD-1 will prolong survival of immunologically "cold" MSS patients. Company summary.Summit Therapeutics Inc. is a clinical-stage biopharmaceutical company with key development centeredon ivonescimab, a novel tetravalent bispecific antibody that targets both PD-1 and VEGF-A to provide dual immunotherapy andanti-angiogenic effects, licensed from its Chinese partner Akeso, Inc (not covered). on Dec 5, 2022. Ivonescimab is approvedin China for the treatment for1)2L EGFR-mutant NSCLC in combo with chemo2)1L PD-L1 positive NSCLC as monotherapy, Pipeline overview and key upcoming catalysts.Ivonescimab is currently being evaluated across multiple Phase III trials innon-small cell lung cancer and other solid tumors in China by its partner Akeso and in the U.S. by Summit, see Exhibit 1. Of note,under the collaboration terms, Summit’s licensed territories for ivonescimab include the United States, Canada, Europe, Japan,Latin America (including Mexico, Central America, South America, and the Caribbean), the Middle East, and Africa, while Akeso Summit is currently running 3 Ph3 studies in NSCLC - HARMONi, HARMONi-3, and HARMONi-7. All these 3 Global studiesset both mOS and mPFS as their co-primary endpoints vs. only mPFS as primary endpoint in China studies, would include the patients from China studies that qualify for the Global study enrollment criteria for analysis. •HARMONiis evaluating ivonescimab added to chemo vs chemo in 2L EGFRm NSCLC. The primary analysis for HARMONistudy was disclosed in 2025 with statistically significant improved mPFS but not hit mOS (PR LINK). Longer follow-upshowed a slightly improved OS curve separation but was not designed for statistical analysis. FDA has accepted the BLAapplication from data profile of HARMONi and set thePDUFA date of November 14, 2026. •HARMONi-3is evaluating ivonescimab+ chemo combo vs pembro + chemo in 1L NSCLC (PD-L1 all comers, squamous[sq] and non-squamous [nsq]). The sq and nsq patients would be evaluated separately, with the final mPFS and interim OSanalysis would be in 2H26 for sq patients, and in 1H27 for nsq patients. The company announced in their 4Q25 earnings thatthey added a interim PFS readout for the sq patients in 2Q26, which most likely failed to achieve statistical significance as •HARMONi-7study was further initiated in 2025 to evaluate ivonescimab mono-therapy vs pembro mono-therapy in 1LNSCLC (PD-L1 high); the study is still enrolling patients with a primary completion estimated in April 2028. In November 2025, Summit initiated another Ph3 studyHARMONi-GI3to evaluate ivonescimab plus chemo compared to bevacizumab plus chemo as first line therapy in patients with unre