Genzyme said Friday its experimental drug tolevamer, a treatment for diarrhea associated with the intestinal infection Clostridium difficile, worked no better than a standard antibiotic, sending the company's shares down more than 5 percent.
Results from the first of two late-stage, or Phase III, clinical trials, showed the drug was no more effective than the standard antibiotic vancomycin.
The results represent a blow to Genzyme , one of the world's biggest biotechnology companies, as tolevamer had been considered one of the more promising drugs in its pipeline.
"We view the tolevamer program as dead," said Geoffrey Meacham, an analyst at JP Morgan, in a report.
But Bo Piela, a spokesman for Genzyme, said the company still believes in the approach to treating the condition.
"This doesn't take tolevamer out of the game," he said. Still, it hurts the drug's potential for approval any time soon.
"These are disappointing results that alter our expectations about the potential for commercializing tolevamer in the near future," said Henri Termeer, Genzyme's chief executive, in a statement.
The setback is the third for Genzyme in a matter of weeks.
Only yesterday the company said Hylastan, one of its experimental treatments for pain associated with osteoarthritis of the knee, worked no better than traditional steroids.
And last month, the company reported mixed results for a powdered version of its experimental kidney disease drug, Renvela.
Tolevamer is designed to be the first non-antibiotic treatment for the condition, which is caused by a type of bacteria that can overgrow and cause infection in the intestine. The condition itself is often caused by taking antibiotics.
Analysts at Cowen have projected peak sales for the drug of about $200 million if it showed success in preventing recurrences of the condition.
The company's shares fell $3.37 to $61.50 in early trading on Nasdaq.