(Reuters) - Seres Therapeutics Inc said its experimental drug for preventing a bacterial infection of the large intestine missed the main goal in a mid-stage study, sending its shares down 74 percent in premarket trading.
In eight weeks, the drug, SER-109, did not reduce the risk associated with the infection that often leads to diarrhea and serious intestinal conditions.
Patients in the study were suffering from recurrent CDI, the infection which is caused by clostridium difficile, a spore-forming bacterium.
The most common adverse events reported in the SER-109 arm were diarrhea, abdominal pain and flatulence. No drug-related serious adverse events were observed.
Analysts from HC Wainwright & Co had previously said they expected SER-109 to potentially generate about $500 million in worldwide sales in 2025.
The company said it would continue to develop a drug for the condition, which has limited treatment options.
Seres' shares, which closed at $35.77 on the Nasdaq on Thursday, fell to $9.23 before the bell on Friday.
Reporting by Amrutha Penumudi in Bengaluru; Editing by Maju Samuel