Tolvaptan in Japanese patients with later-stage autosomal dominant polycystic kidney disease

A recent study demonstrated that tolvaptan slowed estimated glomerular filtration rate (eGFR) decline in later-stage autosomal dominant polycystic kidney disease (ADPKD) patients. However, Japanese patients were not included in that trial, therefore tolvaptan's efficacy in Japanese patients with advanced chronic kidney disease (CKD) has remained unknown.

In this prospective cohort study, 54 patients with ADPKD who had eGFR ≥ 15 ml/min/1.73 m² and total kidney volume (TKV) ≥ 750 ml were treated with tolvaptan. The primary endpoint was the change in height-adjusted total kidney volume (htTKV) and eGFR after 1-year treatment with tolvaptan. Then, we compared the primary endpoint between later CKD stage (baseline eGFR < 45 ml/min/1.73 m²) and earlier CKD stage (baseline eGFR ≥ 45 ml/min/1.73 m²).

The rate of kidney growth during the 1-year treatment did not differ significantly between earlier and later CKD stages. The median and interquartile range of relative change in htTKV in later CKD stage was 8.2%/year [4.4, 26.6], as compared with 5.7%/year [1.6, 16.4] in earlier CKD stage (p = 0.17). Nor did the rate of eGFR decline between earlier and later CKD stages. The relative annual change in eGFR in later CKD stage was - 9.7%/year [- 15.9, - 2.1], as compared with - 6.8%/year [- 11.1, 0.1] in earlier CKD stage (p = 0.18).

This analysis indicates that the efficacy of tolvaptan for Japanese patients with later stage ADPKD was not significantly different from that of Japanese patients with earlier stage ADPKD.