Opexa Therapeutics Reports Positive Top-line Data in Phase I/II Dose Escalation Trial with TovaxinTM for Multiple Sclerosis THE WOODLANDS, Texas -- Opexa Therapeutics, Inc., a company involved in the development and commercialization of cell therapies, today announced positive top-line data in an open-label Phase I/II dose escalation clinical trial of the investigational T-cell vaccine, Tovaxinâ„¢, for multiple sclerosis. In this one-year, 10-subject dose escalation clinical trial, Tovaxin therapy was shown to be safe and effective. The â€œper-protocolâ€ analysis of Tovaxin therapy achieved a 90% reduction (p = 0.0039) in annualized relapse rate (ARR) in subjects who received one of the three dosage levels; the doses were 6 â€“ 9 x 106, 30 â€“ 45 x 106 or 60 â€“ 90 x 106 attenuated T-cells. Subjects in the study received subcutaneous injections of Tovaxin over a period of 20 weeks (0, 4, 12 and 20 weeks) and were monitored for an additional 32 weeks. The safety profile for all dosage levels revealed no severe adverse reactions related to T-cell vaccination. With increasing dosage, an increase in mild injection site reactions was observed and these resolved within 48 hours. All subjects currently are enrolled in an extension study to collect longitudinal safety and effectiveness data. David McWilliams, president and chief executive officer of Opexa, commented, â€œWe are particularly encouraged by the data from this dose escalation trial. While all three dosage levels were safe and effective, the group treated with the 30 â€“ 45 x 106 T-cell dose achieved a 100% reduction in ARR. The currently enrolling Tovaxin IIb clinical trial is being conducted with the 30 â€“ 45 x 106 T-cell dose.â€ About TERMS The Tovaxin Phase IIb clinical study will include 150 patients in a multicenter, randomized, double blind, placebo-controlled trial designed primarily to evaluate the efficacy, safety and tolerability of the Tovaxin T- cell vaccination with clinically isolated syndrome (CIS) and relapsing-remitting MS (RR-MS) patients. A total of 100 patients will receive Tovaxin, while 50 will receive placebo. The study is designed as a two-arm, 52-week, parallel-group study, whereby patients will be given five subcutaneous injections at 0, 4, 8, 12 and 24 weeks. The analyses will be performed at the end of the 52-week study to assess the safety and efficacy of Tovaxin. The primary efficacy variable is the cumulative number of gadolinium-enhancing lesions on T1-weighted MRI scans summed over the Week 28, 36, 44, and 52 MRIs. The secondary efficacy variables are the cumulative number of new gadolinium-enhancing lesions at Weeks 28-52, the change in T2-weighted lesion volume, and the annualized relapse rate. As of March 19, 2007, Opexa reported that more than 110 patients have been enrolled in the TERMS clinical trial and the Company expects enrollment to be complete by mid 2007. All patients who complete the trial will be eligible to participate in an optional one-year extension study, in which they will receive Tovaxin under an open-label protocol. The open-label study is being planned under a different protocol that will be submitted to the FDA. The TERMS study is being conducted at 36 U.S. sites to evaluate the safety and effectiveness of Tovaxin It is registered on the U.S. National Institutes of Health-sponsored website, www.clinicaltrials.gov, where pharmaceutical companies are required to register trials for medicines that will treat serious or life-threatening diseases or conditions. For more information, visit the TERMS website at www.tovaxin.com. About T-cell Vaccination For a T-cell vaccine to be effective, it should be able to induce T-cell cytotoxic and/or regulatory immune responses against the pathogenic T-cells. Studies of T-cell vaccine have indicated that T-cell vaccination with peripheral blood-derived autologous myelin-peptide selected T-cells in multiple sclerosis patients resulted in the in vivo induction of CD8+ cytotoxic T-cells and CD4+CD25+FoxP3 Tregs specific for T-cell vaccine. The induction of anti-idiotypic cytotoxic CD8+ effector T-cells and anti-ergotypic CD4+CD25+FoxP3 positive Tregs is believed to provide a therapeutically effective dual mechanism of protection to patients treated with Tovaxinâ„¢. The observed regulatory immune responses have been shown to collectively correlate with clinical improvement in treated patients. About Opexa Therapeutics Opexa Therapeutics develops and commercializes cell therapies to treat autoimmune diseases such as MS, rheumatoid arthritis, and diabetes. The Company is focused on autologous cellular therapy applications of its proprietary T-cell and stem cell therapies. The Company's lead product, Tovaxin(TM), a T-cell therapy for multiple sclerosis is in Phase IIb trials. The Company holds the exclusive worldwide license for adult multipotent stem cells derived from mononuclear cells of peripheral blood. The technology allows large quantities of monocyte derived stem cells to be produced efficiently for use in autologous therapy, thus circumventing the threat of rejection. The Company is in preclinical development for diabetes mellitus. For more information, visit the Opexa Therapeutics website at www.opexatherapeutics.com. Safe Harbor Statement This press release contains "forward-looking statements," including statements about Opexa Therapeutics' growth and future operating results, discovery and development of products, strategic alliances and intellectual property, as well as other matters that are not historical facts or information. These forward-looking statements are based on management's current assumptions and expectations and involve risks, uncertainties and other important factors, specifically including those relating to Opexa Therapeutics' ability to obtain additional funding, develop its stem cell technologies, achieve its operational objectives, and obtain patent protection for its discoveries, that may cause Opexa Therapeutics' actual results to be materially different from any future results expressed or implied by such forward-looking statements. Opexa Therapeutics undertakes no obligation to update or revise any such forward-looking statements, whether as a result of new information, future events or otherwise.