The US Food and Drug Administration (FDA) has placed on clinical hold CytRx Corporation's phase IIb clinical trial with arimoclomol for the treatment for amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease).

During a brief telephone conversation with the FDA, the company was informed that this decision was based on the need for additional analysis from previously completed animal toxicology studies with arimoclomol. There are no human adverse safety data obtained from any clinical trials that led to the clinical hold, CytRx said. Arimoclomol has been shown to be safe and well-tolerated after being administered to approximately 185 study volunteers. CytRx has requested further clarification from the FDA, which is expected in the next several weeks. Based on the limited information provided by the FDA, the company has begun preparations to respond, and intends to work diligently to respond as promptly as possible following receipt of an anticipated written correspondence from the FDA.

"We are taking the necessary steps to resolve this matter as expeditiously as possible, and we plan to work with the FDA to provide everything necessary to allow us to resume and move forward with this clinical trial," said Steven A. Kriegsman, president and CEO, CytRx. "CytRx remains committed to the clinical development of this drug candidate."

In June 2007, CytRx announced clinical data from a short-term, rising multiple dose study in 40 healthy volunteers indicating that arimoclomol was safe and well-tolerated at doses as high as 600 mg administered three times daily over a seven-day period.

CytRx is continuing preparations to submit Investigational New Drug (IND) applications to the FDA to begin a phase II clinical trial with arimoclomol in stroke recovery, and a phase II clinical trial with iroxanadine, a second small-molecule drug candidate, as a treatment for diabetic foot ulcers. The company plans to begin the stroke recovery phase II clinical trial in the first half of 2008 and to begin the diabetic foot ulcer phase II clinical trial in the second half of the year, in each case subject to FDA clearance. CytRx has decided to move its planned start of the diabetic foot ulcer trial into the second half of the year in order to allow time to develop a manufacturing process that the company believes may significantly reduce its manufacturing costs.

Arimoclomol is one of CytRx's three orally administered, small molecule compounds. This small molecule drug candidate is believed to function by stimulating a normal cellular protein repair pathway through the activation of "molecular chaperones." Since damaged proteins called aggregates are thought to play a role in many diseases, CytRx believes that activation of molecular chaperones could have therapeutic efficacy for a broad range of diseases.

The FDA has granted fast track designation and orphan drug status to arimoclomol for the treatment of ALS. Arimoclomol has also been granted orphan medicinal product status for the treatment of ALS from the European medicines agency.

ALS is a progressive degeneration of the brain and spinal column nerve cells that control the muscles that allow movement. ALS is one of the most common neuromuscular diseases, affecting an estimated 120,000 people of all races and ethnic backgrounds worldwide.