Corcept Therapeutics ( CORT) shares plummeted Friday after the company announced negative results from a clinical trial on its experimental psychotic depression drug Corlux. The stock plunged 70% in premarket trading to $1.05. The results, which came from one of three phase III trials involving a condition known as psychotic major depression, showed that 30.5% of patients receiving Corlux and 28.6% of those getting the placebo responded to treatment. "There was an unusually high placebo response rate in this trial," says Dr. Robert L. Roe, Corcept's president. Roe says that at day 56 of the trial, around 80% of patients receiving the drug and patients taking a placebo saw a 50% improvement in psychopathology measures. "While we are of course disappointed by these results, we have two other phase III trials under way," Dr. Joseph K. Belanoff, Corcept's CEO, said in a prepared statement. Results from one of the studies are due out next month. Corcept Chief Financial Officer Fred Kurland says the company's cash position allows it to complete the two remaining phase III trials. Phase III is the stage of trials conducted just before a drug is submitted to the Food and Drug Administration for marketing approval.