Summit shares hit record high as cancer drug tops Keytruda in China trial
Summit Therapeutics 
SMMT shares soared as much as 75% to a record high on Monday as a study in China showed some lung cancer patients on the company's experimental drug had better survival rates than those on Merck's blockbuster Keytruda.
The drug developer said on Sunday invonescimab study showed patients lived a median of more than 11 months without a progression in the disease, a statistically significant improvement over Keytruda, the world's biggest selling drug.
The additional data is from a late-stage study conducted by Summit's partner Akeso 
9926, initial results from which were announced in May.
Summit's stock price has since surged more than four times. The shares closed at $19.14 on Monday, boosting the company's market value by over $5 billion to more than $13 billion.
Merck's shares closed 2.1% lower at $115.41.
Analysts, however, downplayed worries around Keytruda facing a challenge from Summit's drug as it remains years away from the market.
J.P. Morgan analyst Chris Schott said the data does not meaningfully alter their view on Keytruda, which is due to go off-patent in the coming years.
Summit did not disclose details about the global trial it plans to start next year. Those trials are crucial as U.S. lawmakers have often doubted studies conducted in China.
The FDA had in 2022 declined approval for treatments from Eli Lilly 
LLY and Hutchmed 
13 that were tested only in China.
Citi analyst Yigal Nochomovitz said data from the global study will be needed to validate the result and if favorable, "invonescimab could dethrone Keytruda and become the new standard".
The therapy is an antibody designed to block a protein called PD-1, which helps the body's immune system to fend off cancer. Keytruda also targets the same protein.