Rexahn Pharmaceuticals, Inc. (NYSE MKT:RNN) a clinical stage biopharmaceutical company developing best-in-class therapeutics for the treatment of cancer, today announced additional data from preclinical studies on the anti-tumor effects of RX-3117, a next generation cancer cell specific nucleoside analog. In the study, oral administration of RX-3117 inhibited tumor growth in 12 different human cancer xenograft models including colon, non-small cell lung, small cell lung, pancreatic, renal, ovarian, and cervical cancer. In addition, RX-3117 inhibited the growth of human cancer cells lines shown to be resistant to the anti-cancer effects of gemcitabine, including in the primary low-passage human pancreatic tumorgraft model.

“Resistance to the anti-cancer effects of gemcitabine represents a major clinical issue in the treatment of cancer patients. Up to 25% of cancer patients receiving one or more cycles of gemcitabine rapidly become resistant to its anti-cancer activity. Based on study results to date, both preclinical and clinical, we believe RX-3117 holds the potential to be used for the treatment of tumors that do not respond to gemcitabine and other chemotherapeutic drugs,” commented Rexahn’s CEO, Peter D. Suzdak, Ph.D.

RX-3117 showed greater efficacy (tumor growth inhibition) as compared to gemcitabine in four different xenograft animal models with gemcitabine resistant human cancer cell lines: colorectal cancer (Colo205), small cell lung cancer (H69), cervical cancer (CaSki) and pancreatic cancer (CTG-0298).

Additionally, in a mouse xenograft model using human colorectal cancer cells, those treated with RX-3117 showed significantly longer survival as compared to those receiving other treatments. Mice treated with RX-3117 showed 100% survival through day 95 after initial treatment, compared to 13% of mice treated with gemcitabine, and 25% of mice treated with irinotecan, both FDA-approved drugs.

Results of these studies were presented in a poster titled, “A novel small molecule cytidine analog, RX-3117, shows potent efficacy in xenograft models, even in tumors that are resistant to treatment with gemcitabine,” at the American Association for Cancer Research (AACR) Annual Meeting 2014 on April 6, 2014.

Earlier this year, Rexahn initiated a Phase Ib trial for RX-3117. The trial is a multi-center dose-escalation study which is evaluating the safety, tolerability, dose-limiting toxicities and maximal tolerated dose (MTD) of RX-3117 in patients with solid tumors. Secondary endpoints include characterizing the pharmacokinetic profile of RX-3117 and evaluating the preliminary anti-tumor effects of RX-3117.

In August 2012, Rexahn reported the completion of an exploratory Phase I clinical trial of RX-3117 in cancer patients conducted in Europe, to investigate the oral bioavailability, safety and tolerability of the compound. In this study, oral administration of RX-3117 demonstrated an oral bioavailability of 56% and a plasma half-life (T1/2) of 14 hours. In addition, RX-3117 was safe and well tolerated in all subjects throughout the dose range tested.

About RX-3117

RX-3117 is a next generation nucleoside analog that is activated (phosphorylated) by the enzyme Uridine Cytidine Kinase (UCK) and inhibits both DNA and RNA synthesis which induces apoptotic cell death of tumor cells. UCK is overexpressed in multiple human tumors, but has a limited presence in normal tissues. This unique specificity for cancer cells may lead to an improved efficacy and safety profile in cancer patients. RX-3117 also mediates the downregulation of DNA methyltransferase 1 (DNMT1), an enzyme responsible for the methylation of cytosine residues on newly synthesized DNA and also a target for anticancer therapies. Preclinical studies have shown RX-3117 to be effective in both inhibiting the growth of various human cancer xenograft models, including colon, lung, renal and pancreas, as well as overcoming chemotherapeutic drug resistance.

About Rexahn Pharmaceuticals, Inc.

Rexahn Pharmaceuticals is a clinical stage biopharmaceutical company dedicated to developing best-in-class therapeutics for the treatment of cancer. Rexahn currently has three clinical stage oncology candidates, Archexin®, RX-3117, and SupinoxinTM (RX-5902) and a robust pipeline of preclinical compounds to treat multiple types of cancer. Rexahn has also developed proprietary drug discovery platform technologies in the areas of Nano-Polymer-Drug Conjugate Systems (NPDCS), nano-medicines, 3D-GOLD, and TIMES. 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.