May 21, 2003

News Release: CytRx Acquires Broad Product License for Breakthrough DNA-Based HIV Vaccine

In a windfall step that prominently places the company at the center of DNA-based HIV vaccine development, CytRx Corporation (Nasdaq: CYTR) today announced it has licensed from the University of Massachusetts Medical School (UMMS) the exclusive worldwide commercial rights to a novel DNA-based HIV vaccine. Additionally, $15 million has been awarded from the U.S. National Institutes of Health (NIH) earmarked specifically for the Phase I clinical study and evaluation of this vaccine technology. 'In the last decade there has been significant interest in and investment devoted to AIDS vaccine research and we believe the UMMS technology currently stands at the forefront of DNA-based HIV vaccine development,'said Steven A. Kriegsman, the company's chief executive officer. 'With this license, which includes a pending patent application with broad coverage claims, CytRx is in a strong and enviable position with regard to future products that leverage the potential of DNA-based HIV vaccines. We are very excited that our vaccine technology is incorporated in the NIH funded clinical study to begin within the next six months.'Kriegsman noted that if the study is successful, it should open the door for further funding in more advanced clinical trials.

The lead vaccine candidates under development by Shan Lu, M.D., Ph.D., Associate Professor of Medicine at UMMS, seek to overcome certain obstacles that have challenged other HIV vaccine strategies. Among the challenges are the uses of antigens from laboratory strains of HIV or limited viral isolates that do not necessarily represent active strains existing in patients. Complicating this further are the many HIV subtypes that exist.

Dr. Lu's team has created HIV vaccines based on a unique cocktail of human HIV-1 primary isolates from several genetic subtypes of HIV. Advantages of this approach include what CytRx believes are a greater chance of maintaining efficacy despite the high mutation rate of HIV, a broader immune response against divergent HIV-1 glycoproteins and the possible ability to neutralize a wide spectrum of HIV-1 viruses.

Dr. Lu commented, 'While there are significant hurdles to HIV vaccine development, mounting evidence exists for the use of DNA-based HIV vaccines in combination with various boosters to induce protective responses. The $15 million NIH grant permits Advanced BioScience Laboratories, Inc., which has a vaccine booster, to co-develop the vaccine with UMMS. Recent animal studies indicate promising immune response data and we look forward to advancing our vaccine candidates into the clinic.'

According to the World Health Organization, in December 2002, more than 42 million people worldwide were living with HIV/AIDS. Approximately 5 million people were newly infected and HIV/AIDS caused 3.1 million deaths in 2002.

CytRx previously announced it formed a broad-based strategic alliance with UMMS, which included the signing of exclusive licensing agreements for the use of RNAi (RNA interference) technology in the development of therapeutic products within the fields of obesity, type II diabetes and cancer. The financial terms of the HIV license were not disclosed by the parties for competitive reasons.

ABOUT THE UNIVERSITY OF MASSACHUSETTS MEDICAL SCHOOL

The University of Massachusetts Medical School (UMMS), based in Worcester, MA, is one of the fastest growing academic health centers in the country. UMMS has built a reputation as a world-class research institution, consistently producing noteworthy advances in clinical and basic research. The Medical School attracts more than $143 million in research funding annually, 80% of which comes from federal funding sources. Research funding enables UMMS scientists to explore human disease from the molecular level to large-scale clinical trials. Basic and clinical research leads to new approaches for diagnosis, treatment and prevention of disease. Visit www.umassmed.edu for additional information.

ABOUT CYTRX CORPORATION

CytRx Corporation is a biopharmaceutical company engaged in the development and commercialization of large market opportunity products in a variety of therapeutic categories. The company recently has formed a broad-based strategic alliance with the University of Massachusetts Medical School to develop novel compounds for obesity, diabetes and oncology based on a promising new technology known as RNA interference (RNAi). CytRx is seeking strategic partners to complete the development of FLOCOR, a product for the treatment of sickle cell disease and which may have applications in cancer and disorders such as stroke and heart attack. The company has licensed its TranzFect delivery technology for DNA-based vaccines for certain diseases. A CytRx subsidiary also holds interests in two development stage genomics-based healthcare companies. For more information, visit the CytRx's website at www.cytrx.com .

CAUTIONARY NOTICE ABOUT 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, that 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 time and expense to develop the DNA-based HIV vaccine and commercial medical applications for the RNAi technology, the uncertainty of potential results from future clinical trials for these applications and the need for FDA approval of these applications, the need for additional capital for CytRx to make milestone payments and to possibly fund research for the DNA-based HIV vaccine and for milestone payments and to fund research for RNAi applications, and the risk of CytRx's licensed patents for the DNA-based HIV vaccine and other products not being issued or being challenged after issuance. Additional uncertainties and risks are 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.

SOURCE CytRx Corporation

Steven A. Kriegsman, Chief Executive Officer, This email address is being protected from spambots. You need JavaScript enabled to view it. , or Kathryn Hernandez, Corporate Secretary, This email address is being protected from spambots. You need JavaScript enabled to view it. , both of CytRx Corporation, +1-310-826-5648

http://www.umassmed.edu

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