FimAsartaN proTeinuriA SusTaIned reduCtion in comparison with losartan in diabetic chronic kidney disease (FANTASTIC): Study protocol for randomized controlled trial

Background: Fimasartan is the ninth angiotensin receptor blocker to be developed. However, it has not yet been evaluated for reno-protective effects in hypertensive diabetic chronic kidney disease (CKD). The target blood pressure (BP) for hypertensive diabetic CKD is also a controversial topic. This trial was designed to assess the reno-protective effects of fimasartan compared to those of losartan as a primary outcome. This study also compares the two drugs with regard to cardiovascular and renal outcomes in accordance with target systolic BP (SBP) (as secondary outcomes). Methods: This study is a prospective, phase III, randomized, double-blind, active-controlled, non-inferiority, four-parallel group, dose-titration, multicenter trial. We recruit patients with hypertensive diabetic CKD with overt proteinuria. Participants will be randomized into four groups (1:1:1:1): fimasartan standard SBP control (SBP<140mmHg); fimasartan strict SBP control (SBP<130mmHg); losartan standard SBP control; and losartan strict SBP control. After 24weeks, all individuals are treated with fimasartan for an additional 120weeks in an open-label design, maintaining their assigned SBP control groups as randomized. The primary endpoint is the rate of change in proteinuria, which is assessed using the spot urine albumin-creatinine ratio at 24weeks. The secondary endpoints are the cardiovascular and renal outcomes at 144weeks compared between the strict SBP and standard SBP control groups. Discussion: The FANTASTIC is a clinical study to provide: (1) the reno-protective effect of fimasartan; and (2) the target BP to reduce adverse outcomes in hypertensive diabetic CKD with overt proteinuria. Trial registration: Clinicaltrials.gov, NCT02620306. Registered on 1 December 2015.