Rexahn Pharmaceuticals, Inc. (NYSE Amex: RNN), a clinical stage pharmaceutical company dedicated to developing and commercializing first-in-class oncology therapeutics, today announced that it has been issued a United States patent (No. 8,314,100), titled “1-[6,7-substituted alkoxyquinoxalinyl) aminocarbonyl]-4-(hetero) arylpiperazine derivatives.” This new patent covers Rexahn’s quinoxalinyl-piperazine compounds, the process for the preparation of such compounds and their pharmaceutical composition. The patent includes Rexahn’s RX-5902, a first-in-class p68 helicase inhibitor, that is an orally available new chemical entity exhibiting potent antitumor properties in several types of tumors. RX-5902 has also shown to possess strong anti-proliferative activity against known anti-cancer drug-resistant cancer cells, and a synergistic effect with known anti-cancer drugs. Rexahn has previously been awarded patents for quinoxalinyl-piperazine compounds in Europe, Australia, Canada and Mexico. “We are very pleased to gain this important intellectual property protection for this exciting class of compounds in oncology. This patent is significant step forward in the development of RX-5902, and further strengthens our overall global intellectual property position in oncology,” said Rick Soni, President of Rexahn. About Rexahn Pharmaceuticals, Inc. Rexahn Pharmaceuticals is a clinical stage pharmaceutical company dedicated to developing and commercializing first-in-class and market leading therapeutics for cancer, CNS disorders, sexual dysfunction and other unmet medical needs. Rexahn currently has three drug candidates in Phase II clinical trials, Archexin®, Serdaxin®, and Zoraxel™ and a robust pipeline of preclinical compounds to treat multiple cancers and CNS disorders. Rexahn also operates key R&D programs of nano-medicines, 3D-GOLD, and TIMES drug discovery platforms. For more information, please visit www.rexahn.com. Safe Harbor To the extent any statements made in this press release deal with information that is not historical, these are forward-looking statements under the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about Rexahn’s plans, objectives, expectations and intentions with respect to future operations and products and other statements identified by words such as “will,” “potential,” “could,” “can,” “believe,” “intends,” “continue,” “plans,” “expects,” “anticipates,” “estimates,” “may,” other words of similar meaning or the use of future dates. Forward-looking statements by their nature address matters that are, to different degrees, uncertain. Uncertainties and risks may cause Rexahn’s actual results to be materially different than those expressed in or implied by Rexahn’s forward-looking statements. For Rexahn, particular uncertainties and risks include, among others, the difficulty of developing pharmaceutical products, obtaining regulatory and other approvals and achieving market acceptance; the marketing success of Rexahn’s licensees or sublicensees; the success of clinical testing; and Rexahn’s need for and ability to obtain additional financing. More detailed information on these and additional factors that could affect Rexahn’s actual results are described in Rexahn’s filings with the Securities and Exchange Commission, including its most recent annual report on Form 10-K and subsequent quarterly reports on Form 10-Q. All forward-looking statements in this news release speak only as of the date of this news release. Rexahn undertakes no obligation to update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.