The 409,000-square-foot Athenex facility is located off Route 5 in the town of Dunkirk.

Athenex, which has built a state of the art facility in the town of Dunkirk off Route 5, was hit with a major setback today. In a news release, the company noted the U.S. Food and Drug Administration said its new drug application for oral paclitaxelplus encequidar for the treatment of metastatic breast cancer is not ready for approval in its present form.

In its complete response letter, the FDA indicated its concern of safety risk to patients. The FDA also expressed concerns regarding the uncertainty over the results of the primary endpoint of objective response rate at week 19 conducted by blinded independent central review.

“Our clinical and regulatory teams are disappointed by the complete response letter,” said Dr. Rudolf Kwan, chief medical officer of Athenex. “We plan to work with the agency to resolve the issues raised in the (complete response letter) and to obtain approval for oral paclitaxel plus encequidar in metastatic breastcancer.”

Athenex’s stock after the announcement took a major nose-dive, falling more than 50%. On Friday, it had closed at 12.10 on the NASDAQ and at noon was at 5.75 per share.

The FDA recommended that Athenex conduct a new adequate and well-conducted clinical trial in a patient population with metastatic breast cancerrepresentative of the population in the U.S. The agency determined that additional risk mitigation strategies to improve toxicity, which may involvedose optimization and / or exclusion of patients deemed to be at higher risk of toxicity, are required to support potential approval of the new drug approval.