Preservation of kidney function irrelevant of total kidney volume growth rate with tolvaptan treatment in patients with autosomal dominant polycystic kidney disease

Background Tolvaptan slowed the rates of total kidney volume (TKV) growth and renal function decline over a 3-year period in patients with autosomal dominant polycystic kidney disease (ADPKD) enrolled in the Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes (TEMPO) 3:4 trial (NCT00428948). In this post hoc analysis of Japanese patients from TEMPO 3:4, we evaluated whether the effects of tolvaptan on TKV and on renal function are interrelated. Methods One hundred and forty-seven Japanese patients from TEMPO 3:4 were included in this analysis (placebo, n = 55; tolvaptan, n = 92). Tolvaptan-treated patients were stratified into the responder group ( n = 37), defined as tolvaptan-treated patients with a net decrease in TKV from baseline to year 3, and the non-responder group ( n = 55), defined as tolvaptan-treated patients with a net increase in TKV. Results Mean changes during follow-up in the placebo, responder, and non-responder groups were 16.99%, − 8.33%, and 13.95%, respectively, for TKV and − 12.61, − 8.47, and − 8.58 mL/min/1.73 m 2 , respectively, for estimated glomerular filtration rate (eGFR). Compared with the placebo group, eGFR decline was significantly slowed in both the responder and non-responder groups ( P < 0.05). Conclusion Tolvaptan was effective in slowing eGFR decline, regardless of TKV response, over 3 years in patients with ADPKD in Japan. Treatment with tolvaptan may have beneficial effects on slowing of renal function decline even in patients who have not experienced a reduction in the rate of TKV growth by treatment with tolvaptan.