SMMT Stock Plummets 25% on Regional Data Differences in NSCLC Study

Core Insights - Summit Therapeutics' shares dropped 25% following the final analysis of the HARMONi study, which evaluated the investigational antibody ivonescimab in non-small cell lung cancer (NSCLC) patients, revealing significant differences in progression-free survival (PFS) between Asian and Western patients [1][6][8] Study Results - The HARMONi study focused on patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who had progressed after EGFR-TKI treatment, assessing PFS and overall survival (OS) as primary endpoints [2] - The initial analysis indicated a 48% reduction in disease progression risk with ivonescimab plus chemotherapy compared to chemotherapy alone, but the final analysis showed a 45% risk reduction in Asian patients versus 33% in Western patients [3][8] - For the OS endpoint, the study showed a 21% reduction in death risk, but results were not statistically significant, with a more favorable trend observed in Western patients [4] Collaboration and Market Rights - Summit is developing ivonescimab in collaboration with Akeso, having acquired exclusive rights to market the drug in the US, Canada, Europe, and Japan, while Akeso retains rights in China where the drug is already approved for two NSCLC indications [5] Investor Sentiment - The stock decline reflects investor disappointment over the unexpected PFS gap and the lack of a clear OS benefit, which the FDA has indicated is necessary for marketing authorization in the US [6][8] Year-to-Date Performance - Year-to-date, Summit's stock has increased by 9%, compared to a 12% growth in the industry [7] Competitive Landscape - Summit's ivonescimab is positioned as a potential replacement for PD-(L)1 inhibitors in NSCLC treatment, being a first-in-class bispecific antibody targeting both PD-1 and VEGF, which may offer advantages over existing therapies [12] - The company is conducting additional late-stage studies for ivonescimab in various NSCLC settings [13] - The bispecific antibody market is competitive, with other companies like BioNTech, Bristol Myers, Pfizer, and Merck developing similar candidates, but Summit is currently ahead in clinical development [14][16]