Pharmacological Inhibition of Cav2.2 Channels by Recombinant Phα1β Toxin (CTK01512-2).

Phα1β is a peptide toxin originally isolated from the venom of the Brazilian spider Phoneutria nigriventer, known for its potent analgesic effects in preclinical models of acute and chronic pain. However, clinical translation has been limited by production constraints. A recombinant analogue, CTK01512-2, was developed and has demonstrated antinociceptive efficacy comparable to the native toxin in diverse experimental models. In this study, we examined the effects of CTK01512-2 on N-type voltage-gated calcium channels (Cav2.2) expressed in transiently transfected HEK-293 cells and confirmed its antinociceptive action in a mouse model of neuropathic pain. CTK01512-2 induced a partial (~50%) and reversible inhibition of Cav2.2-mediated calcium currents, with a calculated half-maximal inhibitory concentration (IC50) of 3.94 nM. In contrast to ω-conotoxin MVIIA, a clinically approved irreversible Cav2.2 blocker, CTK01512-2 allowed current recovery after washout, indicating reversible binding. Notably, the toxin did not significantly alter the voltage dependence or kinetics of channel activation. These findings identify CTK01512-2 as a selective and reversible Cav2.2 channel modulator, underscoring its therapeutic potential as a novel analgesic agent for chronic pain management.