Opexa (OPXA) Presents Tovaxin(R) Data at American Academy of Neurology 2011 Annual Meeting

Apr. 15, 2011 (Business Wire) — Opexa Therapeutics, Inc. (NASDAQ: OPXA), a company developing Tovaxin®, a novel T-cell therapy for multiple sclerosis (MS), today presented important efficacy data at the American Academy of Neurology (AAN) 63rd Annual Meeting.

Clyde Markowitz, M.D., director of the Multiple Sclerosis Center at the University of Pennsylvania, professor of neurology at the University of Pennsylvania School of Medicine and member of Opexa’s Scientific Advisory Board, presented the clinical data during a poster session at AAN. The presentation highlighted important efficacy data from Opexa’s Phase IIb TERMS clinical trial in a subpopulation of patients that had previously not been exposed to or taken any drugs for the treatment of their MS.

In this treatment-free or “naïve” subpopulation, patients treated with Tovaxin demonstrated a significant improvement in Annualized Relapse Rate (ARR) compared to those on placebo. In patients who had at least one relapse in the 12 months prior to enrolling in the study and who had no previous exposure to MS therapy (n=70), Tovaxin reduced their ARR by 64% compared to placebo (p=0.046). The overall ARR for Tovaxin-treated patients dropped to 0.18 relapses/patient per year by the end of the 52-week study. Additionally, 76% of Tovaxin-treated patients remained relapse-free at one year compared with 60% of placebo patients.

“The analysis conducted on this patient subgroup provides critical information on clinical trial design,” stated Dawn McGuire, M.D., Chair of Opexa’s Scientific Advisory Board. “Patients naïve to previous therapy, including those newly diagnosed, represent an excellent target population for future studies. Eliminating a possible “legacy” effect due to previous exposure to MS drugs may increase study power to detect a treatment effect. Results identified in this population are encouraging and support Opexa’s plans to initiate a pivotal clinical study later this year.”

Prior treatment with Disease Modifying Therapies (DMTs), especially immunosuppressants or broad acting T-cell therapies, may influence the ARR in the placebo group by imparting a long-term benefit or “legacy” effect. This could explain the observed decline in ARR for placebo controls in more recent MS clinical trials. The impact of prior therapies on the placebo group would indicate that despite a washout period to remove potential DMTs as defined by pharmacokinetics, a legacy effect might persist.

“These results provide us with useful information regarding future clinical trial design and eventual market positioning for Tovaxin,” commented Neil K. Warma, President and CEO of Opexa. “There are several reports which speak to the large number of patients who decide not to initiate treatment once they have been diagnosed or stop treatment in the first one to two years due to side effects and compliance issues. In the population included in the AAN presentation, we were surprised to find that many of the patients had decided not to take any medication for several years following their initial diagnosis of MS and truly remained treatment-free right up until the start of our Phase IIb trial. For over half of the total population that enrolled in the TERMS trial, Tovaxin was their first choice of treatment, despite there being several drugs on the market. We have always maintained that Tovaxin could be very well positioned to capture newly diagnosed patients and non-compliant patients who, today, are faced with limited treatment options. This analysis strongly supports that belief and, hopefully, provides more encouragement to these patients. We believe that Tovaxin has the potential to treat all MS patients, not only these subgroups, but our understanding of the response rates in the various subpopulations will contribute to the optimal design of future clinical studies.”

About Opexa

Opexa Therapeutics, Inc. is dedicated to the development of patient-specific cellular therapies for the treatment of autoimmune diseases. The Company’s leading therapy, Tovaxin®, is a personalized cellular immunotherapy treatment that is in clinical development for MS. Tovaxin is derived from T-cells isolated from peripheral blood, expanded ex vivo, and reintroduced into the patients via subcutaneous injections. This process triggers a potent immune response against specific subsets of autoreactive T-cells known to attack myelin and, thereby, reduces the risk of relapse over time.

Opexa is preparing for Phase III clinical trials with Tovaxin following the completion of a Phase IIb clinical study in 150 patients with MS. Data from this clinical study show evidence that relapsing-remitting MS patients treated with Tovaxin saw overall clinical and disability benefits over the placebo group, including a clinically relevant decrease in the Annualized Relapse Rate (ARR), and improvement in disability score (EDSS), as well as an excellent safety profile with no serious adverse events related to Tovaxin treatment.

For more information visit the Opexa Therapeutics website at www.opexatherapeutics.com.

Cautionary Statement Relating to Forward – Looking Information for the Purpose of “Safe Harbor” Provisions of the Private Securities Litigation Reform Act of 1995

This press release contains forward-looking statements which are made pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. The words “expects,” “believes,” “anticipates,” “estimates,” “may,” “could,” “intends,” and similar expressions are intended to identify forward-looking statements. The forward-looking statements in this release do not constitute guarantees of future performance. Investors are cautioned that statements in this press release which are not strictly historical statements, including, without limitation, statements regarding the development of the Company’s product candidate, Tovaxin, constitute forward-looking statements. Such forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to differ materially from those anticipated, including, without limitation, risks associated with: our capital position, the ability of the Company to enter into and benefit from a partnering arrangement for the Company’s product candidate, Tovaxin, on reasonably satisfactory terms (if at all), our dependence (if partnered) on the resources and abilities of any partner for the further development of Tovaxin, our ability to compete with larger, better financed pharmaceutical and biotechnology companies, new approaches to the treatment of our targeted diseases, our expectation of incurring continued losses, our uncertainty of developing a marketable product, our ability to raise additional capital to continue our treatment development programs and to undertake and complete any further clinical studies for Tovaxin, the success of our clinical trials, our ability to develop and commercialize products, our ability to obtain required regulatory approvals, our compliance with all Food and Drug Administration regulations, our ability to obtain, maintain and protect intellectual property rights (including for Tovaxin), the risk of litigation regarding our intellectual property rights, the success of third party development and commercialization efforts with respect to products covered by intellectual property rights transferred by the Company, our limited manufacturing capabilities, our dependence on third-party manufacturers, our ability to hire and retain skilled personnel, our volatile stock price, and other risks detailed in our filings with the Securities and Exchange Commission. These forward-looking statements speak only as of the date made. We assume no obligation or undertaking to update any forward-looking statements to reflect any changes in expectations with regard thereto or any change in events, conditions or circumstances on which any such statement is based. You should, however, review additional disclosures we make in our reports filed with the Securities and Exchange Commission, including our Annual Report on Form 10-K for the year ended December 31, 2010.

Opexa Therapeutics, Inc.

Neil K. Warma, 281.775.0600

President & CEO

nwarma@opexatherapeutics.com