Novel methodology to identify TRPV1 antagonists independent of capsaicin activation

TRPV1 was originally characterized as an integrator of various noxious stimuli such as capsaicin, heat, and protons. TRPV1-null mice exhibit a deficiency in sensing noxious heat stimuli, suggesting that TRPV1 is one of the main heat sensors on nociceptive primary afferent neurons and a candidate target for heat hypersensitivity in chronic pain. Several different potent and selective TRPV1 antagonists have been developed by more than 50 companies since the characterization of the receptor in 1997. A consequence of this competitive interest is the crowding of patentable chemical space, because very similar in vitro screening assays are used. To circumvent this issue and to expand our understanding of TRPV1 biology, we sought to take advantage of recent advancements in automated patch-clamp technology to design a novel screening cascade. This SAR-driving assay identified novel modulators that blocked the depolarization-induced activation of outwardly-rectifying TRPV1 currents independent of agonist stimulation, and we correlated the pharmacology to three other innovative assays for higher-throughput screening. Ultimately, we have identified a screening paradigm that would have good predictive value for future TRPV1 drug discovery projects and novel chemical space with a higher probability of gaining intellectual property coverage.