Tonix Pharmaceuticals licenses selective sigma-1 antagonist TNX-4900

Tonix Pharmaceuticals (NASDAQ:TNXP) has secured exclusive worldwide rights to TNX-4900, a selective small-molecule Sigma-1 receptor antagonist positioned as a potential new treatment for chronic neuropathic pain.

The company announced the licensing agreement on Dec. 16, highlighting the molecule’s potency, selectivity, and promising preclinical profile.

TNX-4900 binds human Sigma-1 receptors with a Ki of 7.5 nanomolar and exhibits more than 100-fold selectivity over Sigma-2, a differentiation Tonix said may translate into improved safety and targeted pharmacology.

The compound also demonstrated high brain penetration and an estimated 28% oral bioavailability, supporting its suitability for chronic outpatient use.

In animal models of diabetic and chemotherapy-induced neuropathic pain, TNX-4900 produced significant and sustained reductions in pain behaviors following both acute and chronic dosing.

Notably, Tonix reported no evidence of motor impairment or tolerance development—limitations that challenge many existing pain therapies.

Tonix plans to advance TNX-4900 into expanded pharmacokinetic, formulation, and safety studies as it prepares for IND-enabling development.

The company said the addition of TNX-4900 strengthens its pain and neurology pipeline at a time when demand for non-opioid analgesic options continues to rise.