A multicenter, randomized, double-blind, parallel group, placebo-controlled study to evaluate the renal hemodynamic effects of RLX030 at a dose of 30 µg/kg/day or placebo infused for 24 hours in subjects with chronic heart failure (CHF).

The study is designed to provide data to support the understanding of RLX030*s
Mechanism of Action (MoA) through investigation of the renal hemodynamic
effects at the therapeutic dose of 30 µg/kg/day as i.v. infusion for 24 hours
compared to placebo in subjects with CHF, worsening symptoms and mild to
moderate renal impairment (defined as estimated glomerular filtration rate
(eGFR) of 30-89 mL/min/1.73 m2). To provide a better understanding of RLX030*s
renal hemodynamic effects, renal blood flow and glomerular filtration will be
investigated by means of paraaminohippuric acid (PAH) and iothalamate (IOTH)
clearance. These data will be important for the future use of RLX030 in acute
heart failure (AHF).

Primary objective(s)
To assess the effects of 24 hrs i.v. infusion of RLX030 30µg/kg/day compared to
placebo on renal blood flow (RBF) as measured by PAH clearance in subjects with
CHF and worsening symptoms
To assess the effects of 24 hrs i.v. infusion of RLX030 30µg/kg/day compared to
placebo on glomerular filtration rate (GFR) as measured by IOTH clearance in
subjects with CHF and worsening symptoms

Secondary objective(s)
To assess the effects of 24 hrs i.v. infusion of RLX030 30µg/kg/day compared to
placebo on diuresis, fractional sodium and creatinine clearance in subjects
with CHF and worsening symptoms
To assess the effects of 24 hrs i.v. infusion of RLX030 30µg/kg/day compared to
placebo on central aortic systolic pressure (CASP), and radial arterial pulse
waveform in subjects with CHF and worsening symptoms
To assess the safety and tolerability of 24 hrs i.v. infusion of RLX030 30µg/
kg/day compared to placebo in subjects with CHF and worsening symptoms
To investigate the pharmacokinetics of 24 hrs i.v. infusion of RLX030 30µg/
kg/day in subjects with CHF and worsening symptoms

Exploratory objective(s)
• To explore the effects of RLX030 30µg/kg/day during and after 24 hrs i.v.
infusion compared to placebo on circulating and urinary cardio-renal biomarkers
when administered to subjects with CHF and worsening symptoms.
• To explore the effects of 24hrs i.v. infusion RLX030 30µg/kg/day compared to
placebo on renal blood flow (RBF) and redistribution of blood flow between the
cortical and medullary kidney tissue by PET / CT scanning with 15O-water in a
subset of subjects (at dedicated site only) with CHF and worsening symptoms.

This is a multicenter, double-blind, randomized, placebo-controlled study in
subjects with CHF, worsening symptoms and mild to moderate renal impairment
(eGFR of 30-89 mL/min/1.73 m2).
The study will consist of an up to 21 days screening period, a baseline period
of approximately 24 hours and no loop diuretics administration until start of
study drug and furosemide i.v. infusion, a treatment period of 24 hours, a
wash-out period of 24 hour and a Study Completion evaluation
approximately 4 hours after end of infusion. The duration of constant i.v.
infusion with RLX030 will be 24 hours at a dose of 30µg/kg/day.
Subjects who meet the eligibility criteria at screening will have their
baseline evaluations. All baseline safety evaluation results must be available
prior to dosing. I.v. bolus injection followed by constant i.v. infusion of PAH
and IOTH will start 3 hours before study drug infusion and last until 4 hours
after the end of it. Clearance of PAH and IOTH will be determined for RBF and
GFR assessments. Urine will also be collected in fractions for assessment of
diuresis, sodium and creatinine clearance. CASP and radial arterial pulse
waveform will be recorded using the CASPro device. Safety assessments will
include physical examinations, ECGs, vital signs, standard clinical laboratory
evaluations (hematology, blood chemistry, urinalysis,) adverse event and
serious adverse event monitoring.

Patients will be assigned to one of the following 2 treatment arms in a ratio
of 1:1
• RLX030 30µg/kg/day as intravenous infusion for 24 hours
• Matching placebo as intravenous infusion for 24 hours

Efficacy / pharmacodynamic assessments:
• Renal blood flow (RBF) as measured by PAH clearance
• Glomerular filtration rate (GFR) as measured by IOTH clearance at the end of
the 24 hours infusion are the primary variables.
The filtration fraction (FF) defined as the ratio of GFR divided by RBF in
percent will be derived.

Safety assessments:
• Physical examination
• Body height
• Body weight
• Body temperature
• 12 lead ECG
• Systolic and diastolic Blood pressure (SBP, DBP) and pulse rate (PR)
• Hematology; Blood chemistry; Urinalysis
• Adverse events: from time of first administration of study drug until Study
Completion. Adverse events occurring before starting study treatment but after
signing the informed consent form are recorded on the Medical History/Current
Medical Conditions Case Report Form.
• Serious adverse events: from time of consent until 30 days after Study
Completion
• Concomitant medications/Significant non-drug therapies.

Pharmacokinetic assessments:
• Serum concentration of RLX030 during and 24 hours post infusion
• Serum anti-RLX030 antibody assessment at pre-dose

Other assessments:
• Central Aortic Systolic blood Pressure (CASP), brachial SBP, DBP, PR, mean
arterial pressure (MAP) and radial arterial pulse waveform
• Urine collection intervals for total volume, sodium and creatinine clearance
• PET/CT determination of renal medullary/cortical distribution of renal blood
flow (in selected site(s) in the Netherlands)

Biomarkers:
Biomarker measurements will be obtained from plasma and serum samples to
determine effects relevant to heart and renal failure, cardiovascular risk, and
RLX030*s MoA and from urine samples for biomarkers of early kidney damage.
• Circulating cardio-renal biomarkers including but not limited to NT-proBNP,
CTpro-ET1, hsTnT, hsCRP, TNF alpha, Il-1beta and Il-6, copeptin, aldosterone,
cystatin C and other exploratory biomarkers as to be determined
• Urinary biomarkers of early kidney damage which may include cystatin C, KIM-1
and NGAL

The list may be changed or expanded further, as it is recognized that more
relevant or novel biomarkers may be discovered during the conduct of this
study.