Rexahn Pharmaceuticals, Inc. (NYSE MKT:RNN), a clinical stage biopharmaceutical company developing best-in-class therapeutics for the treatment of cancer, today announced an update in its Phase I multi-center dose-escalation study to evaluate the safety, tolerability, dose-limiting toxicities and maximum tolerated dose (MTD) of Supinoxin™ (RX-5902) in cancer patients with solid tumors.

Enrollment into four dose groups has been completed (25, 50, 100 and 150 mg) and no drug related adverse events have been reported. The fifth dose group (225 mg) is ongoing. The maximum tolerated dose of Supinoxin has not yet been achieved. Pharmacokinetic analysis has shown that Supinoxin displays dose-proportional exposure and an estimated oral bioavailability of 51%.

“With the fourth dosing group now complete, we continue to be encouraged by the pharmacokinetics and safety of Supinoxin in patients who have received multiple cycles of treatment. We are on schedule to complete enrollment of patients in this clinical trial by the end of 2014," stated Rexahn's Chief Executive Officer, Peter D. Suzdak, Ph.D. “We look forward to the data from this trial, which will further guide the clinical development of this compound.”

The Phase I trial of Supinoxin, which was initiated in August 2013, is a dose-escalation study designed to evaluate the safety, tolerability, dose-limiting toxicities and MTD in patients with solid cancer tumors that have previously failed treatment with approved therapies and shown progression of disease. Secondary endpoints include pharmacokinetic analysis and evaluating the preliminary anti-tumor effects of Supinoxin. This trial is being conducted in three clinical oncology centers in the United States. Each patient has the ability to continue on the drug up to six cycles of treatment (a dosing cycle is defined as 3 weeks of drug treatment followed by 1 week off) if no disease progression is seen. Patients are assessed by CT or MRI prior to the start of therapy and after every two cycles of therapy to assess tumor progression. The trial is using an accelerated dose-escalation design: one patient is treated per dose cycle until a grade 2 related adverse event occurs then three patients will be treated per dose cycle. The decision to escalate dose is made by the data monitoring safety board (DMSB) after completion of one cycle of treatment based on safety and tolerability. Patients have the possibility to receive up to 6 cycles of treatment if the disease does not progress. Tumor biopsy samples are taken to assess the biomarker phospho-P68.

About Supinoxin™ (RX-5902)

Supinoxin (RX-5902) is an orally administered, potential first-in-class, small molecule inhibitor of phosphorylated-p68 RNA helicase (P-p68). P-p68, which is selectively expressed in cancer cells and is absent in normal tissue, increases the activity of multiple cancer related genes including cyclin D1, c-jun and c-myc, and plays a role in tumor progression and metastasis. Over-expression of P-p68 has been observed in solid tumors, such as melanoma, colon, ovarian and lung tumors. In preclinical studies, Supinoxin has been shown to inhibit proliferation of cancer cells in 18 human cancer cell lines including breast, colon, pancreas, ovarian, and stomach cancers, and showed potent activity in drug-resistant cancer cells. In an animal model, where human cancer cells from melanoma, pancreas, renal or ovarian cancers were grafted into animals, treatment with Supinoxin resulted in a significant reduction in tumor growth.

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.