Cadence Pharmaceuticals ( CADX) said on Friday that in a pivotal late-stage trial, its IV-administered Acetavance for pain and fever didn't meet a primary endpoint.Shares of the San Diego-based biopharmaceutical company plunged $8.43, or 60.3%, to $5.59 after Cadence said the drug didn't demonstrate a statistically significant reduction in patients' pain over 48 hours compared to the placebo after abdominal gynecologic surgery. Acetavance did reduce fever in a separate, smaller study, and was safe and well-tolerated in both studies, according to the company. The drug was successful in prior late-stage studies on postoperative pain, and is currently sold in Europe by Bristol-Myers Squibb ( BMY). Cadence said in a conference call that it will meet with the FDA and discuss the study and results development program. Aside from Acetavance, Cadence is also developing a drug for the prevention of catheter-related infections.