Opexaís lead product candidate is Tovaxin, a novel T-cell vaccine for the treatment of multiple sclerosis (MS) that is specifically tailored to each patientís disease profile. Opexa believes the potential combination of efficacy, superior safety, improved tolerability and patient-friendly administration schedule may position Tovaxin as the MS treatment of choice as compared to existing therapeutic options.

Top-line results from the Phase IIb Tovaxin for Early Relapsing Multiple Sclerosis (TERMS) study demonstrated a positive trend in reduction in annualized relapse rate for Tovaxin-treated patients as compared to placebo, as well as an excellent safety profile with no serious adverse events related to Tovaxin treatment.

MS and Tovaxin
MS is a chronic, progressive inflammatory disease that attacks the myelin sheath that surrounds and insulates nerve fibers and facilitates the conduction of nerve impulse transmissions in the central nervous system (brain and spinal cord). In patients with MS, it is believed that activated T-cells (myelin reactive T-cells or MRTCs) infiltrate the central nervous system and trigger the attack on the myelin sheath (called demyelination), while also inducing a damaging general pro-inflammatory immune response. Ultimately, the nerve fiber axons become damaged and cause impulse transmissions to diffuse into the tissue, resulting in the symptoms and disability associated with the disease.

To produce the Tovaxin vaccine, Opexa uses its innovative T-cell platform to isolate MRTCs from an MS patientís blood and then expand them ex vivo to create an appropriate therapeutic dose. The attenuated T-cells, which comprise the Tovaxin vaccine, are then reintroduced into the patient via subcutaneous injection to trigger the immune system to attack that patientís specific MRTCs.

Mechanism of Action
Tovaxin possesses a unique dual mechanism of action that combats the demyelination of the nerve fibers in the central nervous system, the underlying cause of MS. Clinical results have demonstrated that Tovaxin produces the following therapeutic effects:
  • Anti-idiotypic effect - The vaccine induces an immune response that depletes the circulating pathogenic MRTCs that attack the myelin sheath of nerve fibers and cause the symptoms of MS.
  • Anti-ergotypic effect - Tovaxin also works to rebalance a patientís overall immune system by causing a shift from pathogenic inflammatory T-cells to anti-inflammatory T-cells.
Competitive Advantages
Tovaxinís dual mechanism of action and resulting effects provide the following key advantages:

Efficacy Ė Clinical trials conducted to date demonstrate that Tovaxin may result in a reduction in Annualized Relapse Rate (ARR) for patients with Clinically Isolated Syndrome (CIS), Relapsing-Remitting Multiple Sclerosis (RRMS) and Secondary-Progressive Multiple Sclerosis (SPMS) comparable to currently available MS therapeutics.

Safety and Tolerability - Tovaxin treatment selectively targets and depletes the pathogenic T-cell population. It is not a general immune suppressant and accordingly, is not associated with the serious side effects seen by those MS treatments that function by systemically suppressing the immune system. In clinical trials conducted to date, including the 150-patient Phase IIb study, there have been no serious adverse events associated with Tovaxin treatment.

Customized Therapy Ė Using Opexaís proprietary epitope analysis assay, the Company customizes Tovaxin treatments to specifically target an individualís disease progression and/or modification.

Improved Compliance Ė Tovaxinís treatment regimen of five subcutaneous injections per year may provide significant compliance benefits to both patients and physicians.

Opexa believes the potential combination of comparable/enhanced efficacy and superior safety, tolerability and administration may position Tovaxin as the MS therapy of choice when compared to existing therapeutic options.

Opexa manufactures Tovaxin in its Good Manufacturing Practice ("GMP") facility. The Opexa facility provided adequate capacity for its Phase II program and has expansion capability to meet Phase III manufacturing requirements.