Of the 245 patients who received esaxerenone monotherapy in the main long-term phase 3 study, 102 continued the 52-week therapy, of whom 57 had biomarker data available. Of these, 25 patients who remained on esaxerenone monotherapy until week 52 were included in the current analysis (Supplementary Material Table S2); none were taking concomitant antihypertensive medication.

Baseline characteristics did not differ markedly between the present substudy group and the main long-term phase 3 study. Urinary biomarkers from 24-h urine collection were not measured in all patients of the long-term study (Table 1 and Supplementary Material Table S3).

Esaxerenone monotherapy was associated with consistent reductions in systolic BP/diastolic BP in the substudy population (− 20.8/− 10.3, − 27.6/− 15.2, and − 23.5/− 13.1 mmHg at 12, 28, and 52 weeks, respectively; p < 0.001 vs baseline) (Fig. 1 and Supplementary Material Table S4). The antihypertensive effect of monotherapy was similar to that observed in the main study (Fig. 1).

Mean (standard deviation) sitting blood pressure in the main study and the esaxerenone monotherapy substudy. DBP diastolic blood pressure, SBP systolic blood pressure. †p < 0.001 vs baseline

PAC and PRA significantly increased during therapy with esaxerenone at all time points compared with baseline (all p < 0.001 vs baseline, except for PRA at week 28, p < 0.05), and this increase remained constant after 12 weeks (Supplementary Material Table S4). Although the patients in this study did not have any comorbidities associated with renal- or heart failure-related diseases and the values were within the normal range, both hANP and NT-proBNP decreased, and the decrease at 52 weeks was significant (change from baseline at week 52: hANP, − 5.5 pg/mL, p < 0.05 vs baseline; NT-proBNP, − 46.8 pg/mL, p < 0.05 vs baseline) (Supplementary Material Table S4). The eGFR also decreased overall (Supplementary Material Table S4).

In the first 12 weeks, urinary sodium excretion, potassium excretion, and urine volume decreased significantly (all p < 0.05 vs baseline), and the decrease was sustained until 52 weeks (Supplementary Material Table S4). Spaghetti plots of the respective changes in these parameters from baseline to each time point are shown in Fig. 2. Urine volume decreased at 12, 28, and 52 weeks compared with baseline as follows: − 444.8 mL (geometric mean change, − 26.0%), − 83.0 mL (− 6.7%), and − 319.0 mL (− 18.6%), respectively (Fig. 2a and Supplementary Material Table S4). There was no statistically significant change in urinary sodium concentration, which was 8.9 (geometric mean change, 2.1%), − 7.7 (− 9.0%), and 3.1 (− 0.4%) mEq/L at 12, 28, and 52 weeks, respectively (Fig. 2b and Supplementary Material Table S4). Urinary sodium excretion decreased through 52 weeks, with statistically significant changes at 12 weeks (− 53.1 mEq/day; geometric mean change, − 24.5%, p = 0.0019 vs baseline) and 52 weeks (− 44.0 mEq/day; geometric mean change, − 18.9%, p = 0.0307 vs baseline) (Fig. 2c and Supplementary Material Table S4). Thus, the decrease in urinary sodium excretion could be attributed to the decrease in urine volume.

Changes in urine volume (a), urinary sodium (b), urinary sodium excretion (c), urinary potassium (d), urinary potassium excretion (e), and urinary sodium/potassium ratio (f) from baseline to 12, 28, and 52 weeks (individual patient data). Na sodium, K potassium, SD standard deviation

In line with the results for urinary sodium, urinary potassium concentrations did not change notably at 12, 28, or 52 weeks compared with baseline (Fig. 2d and Supplementary Material Table S4). The mean change in urinary potassium excretion tended to decrease from baseline to − 12.2 (geometric mean change, − 21.5%), − 4.4 (− 14.5%), and − 4.3 (− 8.5%) mEq/day at 12, 28, and 52 weeks, respectively, but the change was statistically significant only at 12 weeks (p = 0.0092 vs baseline) (Fig. 2e and Supplementary Material Table S4). This decreased urinary potassium excretion was also attributed to decreased urine volume. Although the urinary sodium/potassium (Na/K) ratio remained constant during 12 (Δ − 0.3 [− 3.8%]), 28 (Δ − 0.1 [− 0.7%]), and 52 (Δ − 0.5 [− 11.4%]) weeks of esaxerenone administration, the ratio tended to decrease compared with baseline (Fig. 2f and Supplementary Material Table S4).

To clarify the relationship between the antihypertensive effect of esaxerenone and urinary sodium excretion, patients were divided into two groups according to baseline urinary sodium excretion. Urinary sodium excretion was higher than the median value of 193.8 mEq/day in 13 patients and lower than the median value in 12 patients (Supplementary Material Tables S3 and S4).

Baseline characteristics did not differ markedly between patient subgroups based on baseline urinary sodium excretion. Numerical differences were higher male ratio, urine volume, urinary potassium excretion, and Na/K ratio in the higher baseline urinary sodium excretion subgroup versus the lower subgroup (Supplementary Material Table S3).

At 12 weeks, BP decreased significantly in both the lower and higher baseline urinary sodium excretion subgroups (− 14.9/− 7.3 and − 26.6/− 13.2 mmHg, respectively; both p < 0.001 vs baseline); however, there was a significantly greater decrease in the higher baseline urinary sodium excretion subgroup vs the lower baseline urinary sodium excretion subgroup (p < 0.05 for the difference in systolic BP and diastolic BP at 12 weeks between the subgroups) (Fig. 3 and Supplementary Material Table S4).

Mean (standard deviation) change in sitting blood pressure from baseline stratified by baseline urinary sodium excretion. DBP diastolic blood pressure, SBP systolic blood pressure. *p < 0.05 vs baseline, †p < 0.001 vs baseline, ‡p < 0.05 vs subgroup with lower baseline urinary sodium excretion

In the group with higher baseline urinary sodium excretion, urinary sodium excretion, and urine volume decreased with significant differences, and Na/K ratio also decreased. In addition, PRA was consistently slightly elevated throughout the study. There were no other differences (Supplementary Material Table S4).