Opexa Therapeutics Gives Update on Phase IIb Trial of Tovaxin(R) for Treatment of Multiple Sclerosis

Opexa Therapeutics, Inc. (NASDAQ:OPXA), a company involved in the development and commercialization of cell therapies, today provided an update on its 150-patient Phase IIb safety and efficacy study (TERMS) of Tovaxin(R) in multiple sclerosis. The trial design is a U.S. multicenter, randomized, double-blind, placebo-controlled study of subcutaneous Tovaxin in subjects with Clinically Isolated Syndrome (CIS) or Relapsing/Remitting Multiple Sclerosis (RRMS).

Trial Highlights:

-- All 150 patients have received their first vaccine dose in the five dose vaccine series.

-- More than 60% of the total 750 vaccine doses of the study have been delivered.

-- Individualized Tovaxin formulations for all 150 patients have been manufactured with more than 95% of them being unique myelin epitope profiles as identified by Opexa's Epitope Analysis Assay. The variety among the formulations highlights the diversity of myelin epitopes contributing to the disease and supports the individualized therapy approach of Opexa's Tovaxin therapy.

-- The Data Safety Monitoring Board has met three times and reported no safety issues and recommends continuing the trial as planned.

David McWilliams, president and chief executive officer of Opexa Therapeutics, stated, "I am pleased by the steady progress of the trial and recommendation of the Data Safety Monitoring Board and we now look forward to reporting 52-week results in the second half of 2008." McWilliams continued, "We are encouraged that the diverse myelin peptide reactive profile of each patient that we have identified thus far in the study brings us closer to realizing the promise of individual therapy in general, and specifically supports our individualized therapy approach to the treatment of multiple sclerosis."

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 Tovaxin. The observed regulatory immune responses have been shown to collectively correlate with clinical improvement in treated patients.

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.

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, 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.