CytRx Announces Positive Results of Arimoclomol in Preclinical Stroke Recovery Studies Data Indicates a Statistically Significant Improvement in Recovery Following Oral Arimoclomol Administration up to 48 Hours after Stroke Company to Develop Plan for Phase II Clinical Testing LOS ANGELES - CytRx Corporation today announced positive results of additional animal stroke studies indicating that CytRxâ€™s lead drug candidate arimoclomol significantly accelerated the recovery of sensory and motor function in an experimental rat model of stroke, even when treatment was withheld as long as 48 hours after stroke was induced. These data confirm and expand upon preclinical data announced by CytRx in December 2006. Orally-administered arimoclomol is currently in clinical evaluation as a therapeutic treatment for amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). Based on these impressive results, CytRx will begin planning a potential Phase II clinical trial with arimoclomol in stroke patients. "These new animal results show that arimoclomol has the potential to help patients recover from the devastating effects of stroke even if the drug is administered well after the actual stroke event,â€ said CytRx President and CEO Steven A. Kriegsman. â€œWe believe this represents a unique advantage of arimoclomol compared with other stroke drug candidates. If efficacious in stroke patients, it would represent a major breakthrough in improving their quality of life. Furthermore, arimoclomolâ€™s flexibility for delayed intervention may allow substantial penetration into the $58 billion stroke market because the â€™raceâ€™ to get the patient to an emergency room for treatment may not significantly limit its use, unlike other potential stroke drugs.â€ In the present study, stroke was induced in rats by blocking blood flow to parts of the brain causing cerebral oxygen deprivation. The rats then received an oral dose of arimoclomol or control substance daily for 35 days, beginning either 6, 12, 24 or 48 hours after stroke was induced. Recovery from stroke was measured by monitoring sensory motor skills. While motor skills declined dramatically in all study rats immediately after stroke was induced, those treated with arimoclomol recovered dramatically faster and more completely than those untreated regardless of when treatment was initiated. The results were highly statistically significant. In all of the sensory and motor skills tested, even animals whose arimoclomol treatment began 48 hours after stroke were approximately half-way to complete recovery by day seven after stroke, whereas motor skills of untreated animals were unimproved. These data suggest that arimoclomol can accelerate the repair of neurological damage caused by stroke. Unlike arimoclomol, most other stroke drug candidates do not repair the damage caused by stroke, but instead attempt to limit the initial damage caused by stroke. These compounds typically work either by breaking up the clot that stops blood flow, known as thrombolytics, or by defending brain cells from the immediate damage caused by oxygen deprivation, known as neuroprotectants. Since the damage caused by the lack of oxygen is known to occur very early, both types of drug candidates must generally be administered no later than three hours after stroke in order to show significant therapeutic benefit in rats (the â€œtherapeutic windowâ€). Consistent with these animal studies is the fact that the only drug currently approved for stroke, tPA, must be administered in a therapeutic window no greater than three hours after the onset of stroke symptoms to be effective. According to the American Heart Association, less than 25% of the approximately 700,000 Americans who annually suffer stroke reach an emergency room within three hours of the stroke event, indicating the enormous advantage of a drug that could be effective if administered after the three-hour therapeutic window. According to CytRxâ€™s Chief Scientific Officer Jack Barber, Ph.D., â€œThese preclinical results are so compelling that we have decided to evaluate the clinical benefit of arimoclomol in stroke recovery. Among other advantages, the relatively large therapeutic window could dramatically simplify patient enrollment compared with other stroke studies, which will allow us to conduct relatively cost-effective clinical trials in relatively short timeframes. We have begun developing a potential Phase II clinical plan for arimoclomol in stroke recovery.â€ About Stroke According to the American Heart Association, every 45 seconds on average someone in the United States has a stroke, and every three minutes someone dies of stroke. Stroke is the third leading cause of death in the U.S. and accounts for more than 162,000 deaths in the U.S. each year. Of those people who survive a first stroke, 14% will have another one within a year. Stroke is the number one cause of long-term disability among Americans. Between 50% and 70% of stroke survivors regain functional independence; however 15% to 30% are permanently disabled. Three months after stroke, 20% of survivors require institutional care. According to the American Heart Association, stroke cost was approximately $58 billion in both direct and indirect costs in 2006. About Arimoclomol Arimoclomol is one of three CytRx-owned clinical-stage compounds based on its small molecule "molecular chaperone" co-induction technology. Arimoclomol 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. About CytRx Corporation CytRx Corporation is a biopharmaceutical research and development company engaged in the development of high-value human therapeutics. The Company owns three clinical-stage compounds based on its small molecule "molecular chaperone" co-induction technology. In September 2006, CytRx announced that arimoclomol was shown to be safe and well-tolerated at all three doses tested in its Phase IIa clinical trial in patients with ALS, also known as Lou Gehrigâ€™s disease. The Company plans to enter a Phase IIb clinical trial with arimoclomol in ALS in the second half of 2007, subject to U.S. Food and Drug Administration (FDA) approval. The FDA has granted Fast Track designation and Orphan Drug status to arimoclomol for the treatment of ALS and has also been granted orphan medicinal product status for the treatment of ALS by the European Commission. For more information, visit www.cytrx.com. Worcester, Massachusetts based RXi Pharmaceuticals Corporation is a biopharmaceutical research and development company that will focus on developing RNAi-based therapeutics for the treatment of human disease. RXi's initial focus will be on neurodegenerative diseases, oncology, type 2 diabetes and obesity. RXi has licenses to a diverse series of early patents and patent applications that were filed from 1998 to 2006 in the areas of RNAi target sequences, RNAi chemistry and RNAi delivery. The company was founded by CytRx and RNAi pioneers Craig Mello, Ph.D., 2006 Nobel Laureate for discovering RNAi and inventing RNAi therapeutics, Tariq M. Rana, Ph.D., inventor of fundamental technology for stabilizing RNAi and of RNAi nanotransporters, Greg Hannon, Ph.D., discoverer of RNAi mechanism (RISC) and short hairpin RNAi (shRNAi), and Michael Czech, Ph.D., a leader in the application of RNAi to diabetes and obesity. RXi's CEO, Tod Woolf, Ph.D., previously co-invented and commercialized STEALTH(TM) RNAi, one of the most widely used second-generation RNAi research products. Forward-Looking Statements This press release may contain forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended. Such statements involve risks and uncertainties that could cause actual events or results to differ materially from the events or results described in the forward-looking statements, including risks or uncertainties related to the outcome or results of any future pre-clinical or clinical testing of arimoclomol for stroke recovery, and other risks or uncertainties described in CytRx's most recently filed SEC documents, such as its most recent annual report on Form 10-K, all quarterly reports on Form 10-Q and any current reports on Form 8-K filed since the date of the last Form 10-K. All forward-looking statements are based upon information available to CytRx on the date the statements are first published. CytRx undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.