BackgroundEvidence increasingly points to the importance of chronic hypoxia in the tubulointerstitium as a final common pathway to end-stage renal disease (ESRD). Beraprost sodium (BPS) is an orally active prostacyclin (PGI2) analogue demonstrating prevention of the progression of chronic kidney disease (CKD) in various animal models by maintaining renal blood flow and attenuating renal ischemic condition.MethodsThis multicenter, randomized, double-blind, placebo-controlled, phase II trial was designed to determine the recommended dose of the sustained-release form of BPS (TRK-100STP 120 μg/day or 240 μg/day) in Japanese patients with CKD. TRK-100STP was administered to a total of 112 patients. The primary efficacy endpoint was the difference in the slope of the regression line of reciprocal of serum creatinine (1/SCr) over time, obtained by the least-squares method.ResultsRegarding the primary endpoint, statistical superiority of TRK-100STP 240 μg over placebo was not confirmed and so a recommended dose was not determined. Compared to placebo, however, the slope of regression line of 1/SCr, elevation of SCr and serum cystatin C during the treatment period revealed greater improvement at 120 μg, at both doses, and at 240 μg, respectively. In terms of safety, both TRK-100STP treatment groups were well tolerated.ConclusionsAlthough the study failed to meet the primary endpoint, results indicate that TRK-100STP may potentially prevent the decline in renal function of CKD patients independent of blood pressure or urinary protein levels.Trial registrationNCT02480751. June 21, 2015.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0130-5) contains supplementary material, which is available to authorized users.

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BackgroundChronic kidney disease (CKD) is public health concern even in Asian countries. TRK-100STP, a sustained release tablet of an orally-active prostacyclin analogue, beraprost sodium, is suggested to suppress worsening of some parameters of renal filtration function, containing in slope of 1/serum creatinine (1/SCr) vs. time in a phase II clinical trial.Methods/designWe describe the design of the phase IIb/III trial of TRK-100STP, CASSIOPEIR (CRF Asian Study with Oral PGI2 derivative for Evaluating Improvement of Renal function) conducted in approximately 160 centers in China, Hong Kong, Japan, Malaysia, Republic of Korea, Taiwan, and Thailand. A total of 750 patients (n = 250 per group) with primary glomerular disease or nephrosclerosis were planned to be enrolled. Patients were randomized into one of three treatment groups in a double-bind, placebo-controlled manner: TRK-100STP 60 μg b.i.d.; TRK-100STP 120 μg b.i.d.; or placebo. The treatment period is planned to last 2 to 4 years. The primary efficacy endpoint is the renal composite endpoint including doubling of SCr and ESRD (dialysis induction, renal transplantation, or increase in SCr to ≥6.0 mg/dL).DiscussionThis trial targeting CKD patients is designed to (a) demonstrate the superiority of TRK-100STP over placebo using renal composite endpoints, (b) determine the recommended clinical dose, and (c) assess the safety of TRK-100STP in this population and setting.Trial registrationClinicalTrials.gov Identifier: NCT01090037.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2369-15-153) contains supplementary material, which is available to authorized users.

The purpose of the present study was to evaluate the pharmacokinetics of beraprost sodium (BPS) and its active enantiomer, BPS-314d, in Japanese subjects with impaired kidney function. The plasma and urine concentrations of BPS and BPS-314d were measured following the single oral administration of 120 μg of BPS as the sustained-release tablet, TRK-100STP, under fasting conditions to 18 subjects with impaired kidney function (stage 2, 3, and 4 chronic kidney disease [CKD] as categorized by the estimated glomerular filtration rate) and to 6 age-, body weight-, and gender-matched subjects with normal kidney function (stage 1 CKD). The C values (mean ± SD) of BPS in stage 1, 2, 3, and 4 CKD, respectively, were 84.9 ± 22.9, 119.8 ± 36.4, 190.6 ± 137.3, and 240.2 ± 110.5 pg/mL; its AUC were 978 ± 226, 1252 ± 427, 1862 ± 964, and 1766 ± 806 pg·h/mL, respectively, and its cumulative urinary excretion rates were 0.704 ± 0.351%, 0.638 ± 0.292%, 0.485 ± 0.294%, and 0.159 ± 0.136%. The C values of BPS-314d were 22.4 ± 6.4, 30.8 ± 8.5, 46.7 ± 30.6, and 54.4 ± 25.2 pg/mL, its AUC were 155 ± 56, 226 ± 67, 341 ± 176, and 329 ± 143 pg·h/mL, and its cumulative urinary excretion rates were 0.428 ± 0.242%, 0.349 ± 0.179%, 0.356 ± 0.270%, and 0.096 ± 0.099%, respectively. Adverse events were reported in 2 subjects with stage 2 CKD and 1 subject with stage 4 CKD. The C and AUC of BPS and BPS-314d were higher based on the severity of impaired kidney function. No relationship was observed between the incidence of adverse events and the severity, and tolerability was confirmed. We consider that dose adjustment is not necessary, but BPS is more carefully treated in patients with impaired kidney function.