Transcend Therapeutics Inc. halted a Phase III trial of its lead drug, Procysteine, for acute respiratory distress syndrome (ARDS) after an interim analysis of data by an independent safety monitoring board found more patients died in the drug treatment group than in the placebo group.

The Cambridge, Mass.-based company's stock (NASDAQ:TSND) plummeted 61 percent, dropping $4.25 to close at $2.75 Friday.

CEO Hector Gomez said no determination has been made for the increased mortality among patients receiving Procysteine. He said the data will be analyzed to find the cause.

"We don't see a clear drug problem," Gomez said. "I'm confident the trial will resume."

Gomez noted the mortality rate among ARDS patients normally is 40 percent or more.

He speculated patients enrolled in the Procysteine treatment group may have been at a higher risk of dying than those receiving placebo.

"We don't understand today why the patients died," Gomez added. "It is unexpected."

ARDS affects about 150,000 people a year in the U.S. and is triggered by inflammation to the lungs stimulated by other serious conditions, such as infection or trauma.

A total of 213 patients were enrolled in the Phase III trial when it was suspended. Gomez noted the safety monitoring board also made an interim data review after 150 patients were enrolled and concluded in early March the study should continue. The Phase III trial protocols called for a complete enrollment of 352 patients.

Data Analysis Could Take Six Weeks

Gomez said he wants a full analysis of the data from the 213 patients to find the cause of the unexpected deaths. That could take six weeks, he added, noting the company will discuss the issues with the FDA.

Transcend officials informed the FDA and international regulatory authorities about suspension of the trial.

Gomez said Transcend's corporate partner for Procysteine, Boehringer Ingelheim GmbH, of Ingelheim, Germany, will assist in analyzing the Phase III data.

"I've been talking with Boehringer Ingelheim and they will work with us in understanding the problem," Gomez added.

Procysteine delivers the amino acid cysteine into cells to neutralize tissue-damaging toxic molecules called reactive oxygen species (ROS) by boosting cellular production of glutathione, an ROS-neutralizing peptide.

Abnormal levels of ROS and the resulting oxidative damage have been linked to ARDS and other conditions, such as amyotrophic lateral sclerosis, atherosclerotic cardiovascular disease and multiple organ dysfunction.

In two Phase II trials for ARDS, Procysteine, when compared with placebo, allowed patients to rely less on mechanical respirators to breathe. *