Opexa Announces Encouraging Clinical Data on Novel T-Cell Vaccination Therapy for Rheumatoid Arthritis.

THE WOODLANDS, Texas -- Opexa Therapeutics, Inc. (NASDAQ:OPXA), a company involved in the development and commercialization of cell therapies, announced encouraging data from a clinical trial of 15 patients with rheumatoid arthritis (RA). Published in Arthritis & Rheumatism (Vol. 56, No. 2, pp. 453-463), the trial was conducted at the Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences of the People's Republic of China (SIBS), using T-cell vaccination technology exclusively licensed to Opexa. The results demonstrated that T-cell vaccination was well tolerated and, importantly, induced T-cell regulatory immune responses which collectively correlated with substantial clinical improvement in treated patients. Using the American College of Rheumatology (ACR) criteria to measure reduction in joint swelling, substantial clinical improvements were observed for ACR 20 (73.3%), ACR 50 (67.7%) and ACR 70 (55.3%). Overall there was a significant reduction (p < 0.01) in swollen and tender joint counts. The observed changes in the clinical parameters correlated with a significant (p < 0.05) reduction from baseline in serum markers of inflammation, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factor (RF). The open label trial included 15 patients who received T-cell vaccination via six subcutaneous inoculations over a period of 12 months.

David McWilliams, president and chief executive officer of Opexa, commented, "The findings of the study conducted in China was the basis for our previously announced licensing of the technology from SIBS and serves as the cornerstone of our program to develop T-cell vaccination as a therapy for rheumatoid arthritis. The fact that T-cell vaccination induces regulatory immune responses that are associated with improved clinical and laboratory variables in RA patients suggest that further development of this novel technology is warranted."

More About T-Cell Vaccination

For a T-cell vaccine to be effective, it should be able to induce cytotoxic and regulatory immune responses against the pathogenic T-cells. The study conducted by Chen and coworkers, indicated that T-cell vaccination with autologous selected synovial T-cells in rheumatoid arthritis patients resulted in the induction of CD4+ Tregs and CD8+ cytotoxic T-cells specific for T-cell vaccine. Importantly, there was selective expansion of CD4+,V[eth]2+ Tregs that produced interleukin-10 (IL-10) and expressed a high level of transcription factor Foxp3, which coincided with depletion of overexpressed BV14+ T-cells in treated patients. CD4+ IL-10-secreting Tregs induced by T-cell vaccination were found to react specifically with peptides derived from IL-2 receptor [eth]-chain. The expression level of Foxp3 in CD4+ T-cells and increased inhibitory activity of CD4+,CD25+ Tregs was significantly elevated following T-cell vaccination. The observed regulatory immune responses collectively correlated with clinical improvement in treated patients.

About Rheumatoid Arthritis

According to the Arthritis Foundation, rheumatoid arthritis is an autoimmune disease in which the joint lining becomes inflamed as part of the body's immune system activity. Rheumatoid arthritis is one of the most serious and disabling types, affecting mostly women. The CDC reports that arthritis and other rheumatic conditions are the leading cause of disability in the U.S. The U.S. Centers for Disease Control (CDC) estimates that more than two million adults in the U.S. have rheumatoid arthritis, an autoimmune disease. Spending in the U.S. on the treatment of rheumatoid arthritis is projected to grow to $9.5 billion annually by 2013, according to Decision Resources, an independent research firm focused on the pharmaceutical industry.

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.

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.