Prostacyclin analog beraprost sodium efficacy in primary glomerular disease or nephrosclerosis: Analysis of the Japanese subgroup in CASSIOPEIR study

We conducted a multicenter, randomized, double‐blind, placebo‐controlled, phase IIb/III study (CASSIOPEIR) using a renal composite endpoint (i.e., doubling of SCr or end‐stage renal disease) in seven Asian countries/region. CASSIOPEIR compared TRK‐100STP (120 μg and 240 μg) with placebo in patients with non‐diabetic CKD patients with primary glomerular disease or nephrosclerosis (n = 892). However, the superiority of TRK‐100STP over placebo was not observed. A prior phase II study on which the Phase IIb/III study design was based included only Japanese patients. We therefore evaluated TRK‐100STP efficacy and safety in a subgroup of Japanese patients using the CASSIOPEIR dataset. As the timing of treatment initiation is important in CKD, we conducted additional subgroup analyses based on the baseline serum creatinine (SCr) and eGFR. ITT analysis was performed in a Japanese subgroup (n = 339) in which the primary endpoint was the first occurrence of renal composite endpoint. Significant differences were observed for TRK‐100STP 240 μg vs. placebo (P = 0.0493; HR 0.69 [95% CI: 0.47, 1.00]), but no significant difference was observed between TRK‐100 120 μg and placebo (P = 0.3523; HR 0.85). More prominent improvement was observed with TRK‐100STP 240 μg vs. placebo for baseline SCr < 3.0 mg/dL (P = 0.0031; HR 0.43); SCr < 3.5 mg/dL (P = 0.0237, HR 0.59); and eGFR ≥ 10 mL/min/1.73 m(2) (P = 0.0339, HR0.67), respectively. No significant changes in urinary albumin/creatinine ratio and blood pressure were observed. TRK‐100STP was generally well tolerated and most adverse drug reactions were mild or moderate in severity. In conclusion, in the Japanese subgroup of CASSIOPEIR, TRK‐100STP 240 μg/day significantly improved the renal composite endpoint compared with placebo, with greater efficacy in subjects with SCr < 3.5 or eGFR ≥ 10 mL/min/1.73 m(2).