Early AI-driven repurposing study of existing drugs towards the vasopressin V2 receptor

The main goal of this study is the identification of existing drugs that could be repurposed as antagonists of the V2R, a GPCR controlling renal water balance and involved in abnormal cell proliferation, cancer, and renal cyst enlargement. Given its clinical importance, we carried out the reverse screening of a collection of 1882 existing drugs to repurpose them towards V2R by employing PLATO, a home-built target fishing AI-based platform. Five drugs were shortlisted as promising candidates for V2R: cabergoline, clopidogrel, cloxacillin, perphenazine, and zafirlukast. Renal collecting duct MCD4 cells, stably expressing human V2R and AQP2, were used for experimentally testing the effects of the prioritized drugs on V2R responses. FRET studies were conducted to assess whether these drugs affect the DDAVP-induced cAMP responses. Interestingly, zafirlukast, at single-digit nanomolar concentration significantly reduced the DDAVP-dependent cAMP production and water reabsorption, with effects comparable to tolvaptan, a well-known selective V2R antagonist. The molecular rationale behind the observed binding was explained by mapping on the V2R a molecular cleft superimposable to CysLTR1 binding site of zafirlukast. Induced-fit docking simulations demonstrated that zafirlukast engages V2R by adopting a binding conformation closely resembling that of X-ray solved vasopressin. Taken together, our results support the repurposing of zafirlukast as a promising V2R antagonist candidate.