Trevena Inc. believes G protein-coupled receptor ligands that target just one GPCR pathway could provide either better efficacy or fewer side effects than ligands that agonize or antagonize the whole receptor. The company is raising a series B round to build a portfolio of what it calls biased ligands.

GPCR signaling is mediated through two pathways: the G protein pathway and the beta arrestin pathway. The G protein pathway actively signals to elicit a biological response. The beta arrestin pathway has a dual role, both as an off-switch for G protein signaling, and as an active biological signaling pathway itself.