Tolvaptan is a selective arginine vasopressin type 2 receptor antagonist. Tolvaptan reduced the progression of kidney function decline in ADPKD in animal models
[29][30]. The role of arginine vasopressin-mediated cAMP as a driver of fluid secretion into the cysts in ADPKD was demonstrated in preclinical ones. Two multicentric, randomized, placebo-controlled trials evaluated the safety and efficacy of tolvaptan in ADPDK patients. The TEMPO 3:4 trial (NCT00428948, ClinicalTrials.gov) enrolled 1445 ADPKD patients with normal renal function or mild renal insufficiency (CKD1, CKD, baseline eGFR ≥ 60 mL/min per 1.73 m
2). Tolvaptan reduced an increase in kidney volume a 2.8% per compared with a 5.5% per year increase in the placebo group (
p ˂ 0.001) over the 3-year period. Tolvaptan also slowed a decline in kidney function, as measured by reciprocal of serum creatinine level, compared with placebo, −2.61 vs. −3.81 per year (
p ˂ 0.001)
[31]. As expected, there were adverse aquaretic events, such as thirst, polyuria, nycturia, polakisuria and polydipsia. Moreover, clinically important liver involvement with increase of liver enzymes was described in 4.4% of patients. Liver enzymes in all patients normalized after cessation of tolvaptan. TEMPO 3:4 was followed by open label one TEMPO 4:4, the decrease of eGFR decline was found in the following two years
[32]. A second trial, REPRISE (NCT02160145) was designed to evaluate the efficacy and safety of tolvaptan
[33]. A one-year in ADPKD patients with more advanced disease (eGFR 25–65 mL/min per 1.73 m
2) showed a reduction in decline of eGFR in treated patients. The post hoc analysis from open label extension found that tolvaptan also delayed eGFR decline in CKD4 (with eGFR 15 to 24 mL/min per 1.73 m
2)
[34]. A monthly protocol for monitoring liver enzymes is obligatory for 18 months as a prevention of severe hepatic toxicity, followed by 3-month check-up.
Nowadays, therapy with tolvaptan should be recommended to all ADPKD patients with probable rapid progression of the disease. Criteria for tolvaptan use are proposed as follows: 1. age 18–55 years, 2. chronic kidney disease CKD1–4 (eGFR ≥ 25 mL/min per 1.73 m
2), 3. high risk measured by available risk scores (longitudinal diameter > 17 cm by ultrasound, total kidney volume > 750 mL, Mayo imaging classification 1C, 1D, 1E or PROPKD score > 6), and 4. rapid decline of eGFR 3 mL/min per > 1.73 m
2) for 5 years. Mayo imaging classification is based on magnetic resonance and clearly predicts decline in eGFR on the basis of initial total kidney volume
[35]. PROPKD (Predicting Renal Outcomes in Polycystic Kidney Disease) score predicts the prognosis according to molecular genetic analysis in combination with simple clinical information (sex, age at diagnosis of hypertension, age of first episode of macroscopic hematuria, flank pain related to cysts)
[36]. Risk stratification is important because there was no difference of eGFR decline in patients having low risk of ADPKD progression
[37]. Tolvaptan is not recommended in ADPKD patients with predicted mild clinical course.