Tovaxin

Tovaxin is a novel anti-T-cell therapeutic vaccine that parallels the concept of autologous cancer vaccines. Instead of modifying cancerous cells, TovaxinTM consists of attenuated autoreactive T cells. Tovaxin is being developed by Opexa Therapeutics in Houston, Texas

Method of Action
Tovaxin takes a patients own T-cells from a blood sample drawn in the clinic. Attenuation of the patient's T-cells during the vaccine production process renders the cells non-replicating but viable and causes them to elicit an immune response when injected subcutaneously (under the skin) into the patient. This immune response is directed against T-cells within the patient that are self-reactive with myelin. Myelin is the sheath that covers the neurons that are affected in Multiple Sclerosis. This immune response, directed against a specific subset of autoreactive T cells, greatly reduces the number of these autoreactive cells in MS patients. Tovaxin has considerable potential because it attacks the underlying cause of MS rather than just addressing its symptoms.

Status of FDA Trials
In October 2005, the Company presented positive interim research findings of its Phase I/II clinical trials of Tovaxin at the 21st European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and the 10th Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) congress held in Thessaloniki, Greece. The trial results indicated that the treatment appeared safe and well tolerated with no dose-limiting toxicities, and that Tovaxin depletes the myelin-peptide reactive T cells that may contribute to the Multiple Sclerosis (MS) disease processes.

PharmaFrontiers announced in late 2005 that the U.S. Food and Drug Administration's Center for Biologics Evaluation and Research (FDA's CBER) had approved the protocol for its Phase IIb clinical trial of Tovaxin. PharmaFrontiers will be conducting the Phase IIb with its clinical development partner, INC Research, Raleigh, North Carolina.

This multicenter, randomized, double blind, placebo-controlled Phase IIb clinical study is designed primarily to evaluate the efficacy, safety and tolerability of the Tovaxin T Cell therapy with clinically isolated syndrome (CIS) and early relapsing-remitting MS (RR-MS) patients. Additionally, the study of these patients will evaluate biomarkers of Tovaxin's efficacy and to evaluate the effect of Tovaxin on immune deviation and epitope spreading.

All patients who complete the trial will be eligible to participate in an optional one-year extension study, in which they will receive Tovaxin open-label. The open-label study is being planned under a different protocol that will be submitted to the Food and Drug Administration (FDA).