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 < 140 mmHg); fimasartan strict SBP control (SBP < 130 mmHg); losartan standard SBP control; and losartan strict SBP control. After 24 weeks, all individuals are treated with fimasartan for an additional 120 weeks 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 24 weeks. The secondary endpoints are the cardiovascular and renal outcomes at 144 weeks 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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-017-2375-8) contains supplementary material, which is available to authorized users.