Torres et al. examined the effects of tolvaptan on ADPKD-induced renal involvement in their TEMPO 4:4 study and demonstrated that the treatment with tolvaptan significantly improved the annual %TKV in patients with both PKD1-T and PKD1-NT/PKD2 gene mutations compared with the placebo-treated group [13]. The gene discussed is PKD2; the disease is autosomal dominant polycystic kidney disease.