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The availability of highly purified recombinant human relaxin, serelaxin, has allowed clinical trials to be conducted in several indications and the elucidation of its pharmacology in human subjects. These studies have demonstrated that serelaxin has unique haemodynamic properties that are likely to contribute to organ protection and long-term outcome benefits in acute heart failure. Clinical observations support its consideration for therapeutic use in other patient populations, including those with chronic heart failure, coronary artery disease, portal hypertension and acute renal failure. Linked Articles This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc

Background Little is known about mode of death after acute heart failure (AHF) hospitalization. In the RELAX-AHF (Efficacy and Safety of Relaxin for the Treatment of Acute Heart Failure) study, serelaxin, the recombinant form of human relaxin-2, reduced post-discharge mortality at 180 days in selected patients with AHF. Objectives The goal of this study was to assess the effect of serelaxin on specific modes of death in patients with AHF. Methods The RELAX-AHF study randomized 1,161 patients with AHF to 48 h of therapy with intravenous serelaxin or placebo. Patients were followed for vital status through 180 days. A blinded clinical events committee reviewed all deaths and adjudicated a cause of death on the basis of pre-specified criteria. Cox proportional hazard models were used to assess the effect of serelaxin on each mode of death, on the basis of pre-specified groupings of mode of death. Results There were 107 deaths (9.3%): 37 (35%) due to HF, 25 (23%) due to sudden death, 15 (14%) due to other cardiovascular (CV) causes, 19 (18%) due to non-CV causes, and 11 (10%) classified as unknown. The treatment effect of serelaxin was most pronounced on other CV deaths (hazard ratio [HR]: 0.29; 95% CI: 0.12 to 0.73; p = 0.005) and sudden death (HR: 0.46; 95% CI: 0.20 to 1.07; p = 0.065). There was no apparent impact of serelaxin treatment on HF deaths or non-CV deaths. Conclusions In the RELAX-AHF study, the effects of serelaxin on mortality were primarily driven by reduction in mortality from other CV causes and sudden death, without apparent impact on HF deaths. (Efficacy and Safety of Relaxin for the Treatment of Acute Heart Failure [RELAX-AHF]; NCT00520806 )

Aims Serelaxin is effective in relieving dyspnoea and improving multiple outcomes in acute heart failure (AHF). Many AHF patients have preserved ejection fraction (HFpEF). Given the lack of evidence-based therapies in this population, we evaluated the effects of serelaxin according to EF in RELAX-AHF trial.Methods and results RELAX-AHF randomized 1161 AHF patients to 48-h serelaxin (30 mu g/kg/day) or placebo within 16 h from presentation. We compared the effects of serelaxin on efficacy endpoints, safety endpoints, and biomarkers of organ damage between preserved (a parts per thousand yen50%) and reduced (Conclusions In AHF patients with HFpEF compared with those with HFrEF, serelaxin was well tolerated and effective in relieving dyspnoea and had a similar effect on short- and long-term outcome, including survival improvement.

Summary Background Serelaxin, recombinant human relaxin-2, is a vasoactive peptide hormone with many biological and haemodynamic effects. In a pilot study, serelaxin was safe and well tolerated with positive clinical outcome signals in patients with acute heart failure. The RELAX-AHF trial tested the hypothesis that serelaxin-treated patients would have greater dyspnoea relief compared with patients treated with standard care and placebo. Methods RELAX-AHF was an international, double-blind, placebo-controlled trial, enrolling patients admitted to hospital for acute heart failure who were randomly assigned (1:1) via a central randomisation scheme blocked by study centre to standard care plus 48-h intravenous infusions of placebo or serelaxin (30 μg/kg per day) within 16 h from presentation. All patients had dyspnoea, congestion on chest radiograph, increased brain natriuretic peptide (BNP) or N-terminal prohormone of BNP, mild-to-moderate renal insufficiency, and systolic blood pressure greater than 125 mm Hg. Patients, personnel administering study drug, and those undertaking study-related assessments were masked to treatment assignment. The primary endpoints evaluating dyspnoea improvement were change from baseline in the visual analogue scale area under the curve (VAS AUC) to day 5 and the proportion of patients with moderate or marked dyspnoea improvement measured by Likert scale during the first 24 h, both analysed by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00520806. Findings 1161 patients were randomly assigned to serelaxin (n=581) or placebo (n=580). Serelaxin improved the VAS AUC primary dyspnoea endpoint (448 mm × h, 95% CI 120–775; p=0·007) compared with placebo, but had no significant effect on the other primary endpoint (Likert scale; placebo, 150 patients [26%]; serelaxin, 156 [27%]; p=0·70). No significant effects were recorded for the secondary endpoints of cardiovascular death or readmission to hospital for heart failure or renal failure (placebo, 75 events [60-day Kaplan-Meier estimate, 13·0%]; serelaxin, 76 events [13·2%]; hazard ratio [HR] 1·02 [0·74–1·41], p=0·89] or days alive out of the hospital up to day 60 (placebo, 47·7 [SD 12·1] days; serelaxin, 48·3 [11·6]; p=0·37). Serelaxin treatment was associated with significant reductions of other prespecified additional endpoints, including fewer deaths at day 180 (placebo, 65 deaths; serelaxin, 42; HR 0·63, 95% CI 0·42–0·93; p=0·019). Interpretation Treatment of acute heart failure with serelaxin was associated with dyspnoea relief and improvement in other clinical outcomes, but had no effect on readmission to hospital. Serelaxin treatment was well tolerated and safe, supported by the reduced 180-day mortality. Funding Corthera, a Novartis affiliate company.

Objectives The aim of this study was to assess the effects of serelaxin on short-term changes in markers of organ damage and congestion and relate them to 180-day mortality in patients with acute heart failure. Background Hospitalization for acute heart failure is associated with high post-discharge mortality, and this may be related to organ damage. Methods The Pre-RELAX-AHF (Relaxin in Acute Heart Failure) phase II study and RELAX-AHF phase III study were international, multicenter, double-blind, placebo-controlled trials in which patients hospitalized for acute heart failure were randomized within 16 h to intravenous placebo or serelaxin. Each patient was followed daily to day 5 or discharge and at days 5, 14, and 60 after enrollment. Vital status was assessed through 180 days. In RELAX-AHF, laboratory evaluations were performed daily to day 5 and at day 14. Plasma levels of biomarkers were measured at baseline and days 2, 5, and 14. All-cause mortality was assessed as a safety endpoint in both studies. Results Serelaxin reduced 180-day mortality, with similar effects in the phase II and phase III studies (combined studies: N = 1,395; hazard ratio: 0.62; 95% confidence interval: 0.43 to 0.88; p = 0.0076). In RELAX-AHF, changes in markers of cardiac (high-sensitivity cardiac troponin T), renal (creatinine and cystatin-C), and hepatic (aspartate transaminase and alanine transaminase) damage and of decongestion (N-terminal pro–brain natriuretic peptide) at day 2 and worsening heart failure during admission were associated with 180-day mortality. Serelaxin administration improved these markers, consistent with the prevention of organ damage and faster decongestion. Conclusions Early administration of serelaxin was associated with a reduction of 180-day mortality, and this occurred with fewer signs of organ damage and more rapid relief of congestion during the first days after admission.

Background Acute heart failure (AHF) remains a major public health burden with a high prevalence and poor prognosis. Relaxin is a naturally occurring peptide hormone that increases cardiac output, arterial compliance, and renal blood flow during pregnancy. The RELAX-AHF-1 study will evaluate the effect of RLX030 (recombinant form of human relaxin 2) on symptom relief and clinical outcomes in patients with AHF.Methods The protocol includes a completed phase 2 234-patient dose-finding study (Pre-RELAX-AHF) and an ongoing phase 3 1,160-patient trial (RELAX-AHF-1). Patients with AHF and systolic blood pressure >125 mm Hg are randomized within 16 hours of presentation to a 48-hour IV infusion of RLX030 or placebo. The 30 mu g/kg per day dose of RLX030 was chosen for RELAX-AHF-1 based on effects on dyspnea, clinical outcomes, and safety observed in Pre-RELAX-AHF. Primary efficacy end points in RELAX-AHF-1 are (1) the area under the curve of change of the dyspnea Visual Analog Scale from baseline through day 5 and (2) whether the patient reports moderately to markedly better dyspnea at 6, 12, and 24 hours. Secondary efficacy end points include days alive and out of the hospital through day 60 and cardiovascular death or rehospitalization for heart failure or renal failure through day 60. Patients will be followed up through day 180 for mortality. As of September 19, 2011, 978 patients have been enrolled.Conclusions Pre-RELAX-AHF results suggested that infusion of RLX030 may accelerate dyspnea relief and improve prognosis in patients hospitalized with AHF. RELAX-AHF-1 will further evaluate these effects. (Am Heart J 2012;163:149-155.e1.)

Relaxin is a naturally occurring peptide hormone that plays a central role in the hemodynamic and renovascular adaptive changes that occur during pregnancy. Triggering similar changes could potentially be beneficial in the treatment of patients with heart failure. The effects of relaxin include the production of nitric oxide, inhibition of endothelin, inhibition of angiotensin II, production of VEGF, and production of matrix metalloproteinases. These effects lead to systemic and renal vasodilation, increased arterial compliance, and other vascular changes. The recognition of this has led to the study of relaxin for the treatment of heart failure. An initial pilot study has shown favorable hemodynamic effects in patients with heart failure, including reduction in ventricular filling pressures and increased cardiac output. The ongoing RELAX-AHF clinical program is designed to evaluate the effects of relaxin on the symptoms and outcomes in a large group of patients admitted to hospital for acute heart failure. This review will summarize both the biology of relaxin and the data supporting its potential efficacy in human heart failure.

Background Elevated plasma concentrations of liver function tests are prevalent in patients with chronic heart failure (HF). Little is known about liver function in patients with acute HF. We aimed to assess the prevalence and prognostic value of serial measurements of liver function tests in patients admitted with acute decompensated HF. Methods We investigated liver function tests from all 234 patients from the Relaxin for the Treatment of Patients With Acute Heart Failure study at baseline and during hospitalization. The end points were worsening HF through day 5, 60-day mortality or rehospitalization, and 180-day mortality. Results Mean age was 70 ± 10 years, 56% were male, and most patients were in New York Heart Association functional class III/IV (73%). Abnormal liver function tests were frequently found for alanine transaminase (ALT; 12%), aspartate transaminase (AST; 21%), alkaline phosphatase (12%), and total bilirubin (19%), and serum albumin (25%) and total protein (9%) were decreased. In-hospital changes were very small. On a continuous scale, baseline ALT and AST were associated with 180-day mortality (hazard ratios [HRs; per doubling] 1.52 [ P = .030] and 1.97 [ P = .013], respectively) and worsening HF through day 5 (HRs [per doubling] 1.72 [ P = .005] and 1.95 [ P = .008], respectively). Albumin was associated with 180-day mortality (HR 0.86; P = .001) but not with worsening HF (HR 0.95; P = .248). Total protein was associated with only worsening HF (HR 0.91; P = .004). Conclusions Abnormal liver function tests are often present in patients with acute HF and are associated with an increased risk for mortality, rehospitalization, and in-hospital worsening HF.

Aim Patients hospitalized for acute heart failure (AHF) differ with respect of many clinical characteristics which may influence their prognosis and response to treatment. We have assessed possible differences in the effects of serelaxin on dyspnoea relief, 60 Day outcomes and 180 Day mortality across patient subgroups in the RELAX-AHF trial.Methods and results Subgroups were based on pre-specified covariates (age, sex, race, geographic region, estimated glomerular filtration rate, time from presentation to randomization, baseline systolic blood pressure, history of diabetes, atrial fibrillation, ischaemic heart disease, cardiac devices, i.v. nitrates at randomization). Other covariates which may modify the efficacy of AHF treatment were also analysed. Subgroup analyses did not show any difference in the effects of serelaxin vs. placebo on dyspnoea relief or on the incidence of cardiovascular death or rehospitalizations for heart failure or renal failure at 60 days. Nominally significant interactions between some patient subgroups and the effects of serelaxin on 180 days cardiovascular and all-cause mortality were noted but should be interpreted cautiously due to the number of comparisons and the low incidence of deaths in the subgroups at lower risk.Conclusion The effects of serelaxin vs. placebo appeared to be similar across subgroups of patients in RELAX-AHF.

BackgroundClinically relevant endpoints cannot be routinely targeted with reasonable power in a small study. Hence, proof-of-concept studies are often powered to a primary surrogate endpoint. However, in acute heart failure (AHF) effects on surrogates have not translated into clinical benefit in confirmatory studies. Although observing an effect on one of many endpoints due to chance is likely, observing concurrent positive trends across several outcomes by chance is usually unlikely.MethodsPre-RELAX-AHF, which compared 4 relaxin doses with placebo in AHF, has shown favourable trends versus placebo (one-sided P&nbsp

Aims Although dyspnoea is the most common cause of admission for acute heart failure (AHF), more needs to be known about its clinical course and prognostic significance. Methods and results The Pre-RELAX-AHF study randomized 232 subjects with AHF to placebo or four doses of relaxin and evaluated early (6–24 h Likert scale) and persistent [change in visual analogue scale area under the curve (VAS AUC) through Day 5] dyspnoea relief. Worsening heart failure (WHF) was defined as worsening AHF signs and symptoms requiring additional therapy. Patients were followed until Day 180. Early dyspnoea relief was observed in only 25% of all patients, and VAS AUC at 5 days was 45% over baseline values in all patients (32% placebo; 50% all relaxin-treated patients). Worsening heart failure to Day 5 was observed in 16% of all patients (21% placebo; 14% relaxin). Lack of persistent dyspnoea relief and WHF were associated with a longer length of initial hospital stay and worse 60-day outcomes. Conclusion Dyspnoea relief in patients admitted with AHF is often incomplete, and many may show WHF after the initial stabilization. Both lack of persistent dyspnoea relief and in-hospital WHF predict a longer length of stay and worse outcome.

Background: Previous studies have suggested that a lower lymphocyte ratio (Ly%) in the white blood cell (WBC) differential count is related to worse outcomes in patients with acute heart failure (AHF) and other cardiovascular disorders. Methods: In the Pre-RELAX-AHF study, 234 patients with AHF, systolic blood pressure >125 mm Hg and brain natriuretic peptide ≧350 pg/ml or equivalent were randomized to 1 of 4 intravenous doses of relaxin or placebo and followed up for 6 months following randomization. Complete blood count and differential were performed by a central laboratory at baseline and then daily to day 5 and on day 14. Results: The WBC count by itself was not associated with measures of disease severity or outcome, and patients with Ly% 13%, except for a higher baseline WBC count, elevated baseline glucose, older age and higher rates of peripheral vascular disease. However, patients with Ly% Conclusions: Despite no association with any baseline characteristic known to strongly predict outcome in AHF, low Ly% is associated with less symptom relief and worse in-hospital and postdischarge clinical outcomes.

Relaxin is a naturally occurring human peptide initially identified as a reproductive hormone. More recently, relaxin has been shown to play a key role in the maternal hemodynamic and renal adjustments that accommodate pregnancy. An understanding of these physiologic effects has led to the evaluation of relaxin as a pharmacologic agent for the treatment of patients with acute heart failure. Preliminary results have been encouraging. In addition, the other known biologic properties of relaxin, including anti-inflammatory effects, extracellular matrix remodeling effects, and angiogenic and anti-ischemic effects, all may play a role in potential benefits of relaxin therapy. Ongoing, large-scale clinical testing will provide additional insights into the potential role of relaxin in the treatment of heart failure.

The pathophysiology of preeclampsia involves profound systemic vasoconstriction. Its etiology may be related to reduced blood flow to the placenta, leading to the elaboration of soluble, vasoactive factors which increase maternal systemic vascular resistance and cause renal dysfunction. Reduced bioactivity of vascular endothelial growth factor (VEGF) may play a central role in this pathophysiology. Previous clinical studies have strongly suggested that relaxin is a systemic and renal vasodilator. In nonclinical studies, relaxin administration to monkeys has been associated with increased vessel density in the endometrium, and in previous human trials relaxin administration has been highly correlated with increased menstrual bleeding in women. VEGF has been proposed as a mechanism for these endometrial effects. Together, these data suggest that relaxin may be able to relieve systemic and renal vasoconstriction and improve placental perfusion in women with preeclampsia. As a first step in the development program for relaxin in this indication, a multicenter, randomized, double-blind, placebo-controlled phase I safety study in women with severe preeclampsia has been launched in the USA. Three doses of relaxin, 3, 10, and 30 microg/kg of body weight/day, or placebo, will be administered for up to 72 h in women admitted to the hospital for management of their disease. Although the trial is primarily focused on safety, signs of efficacy, such as changes in blood pressure and renal markers, will also be assessed.

To test the hypothesis that relaxin is an important factor supporting implantation, two approaches have been carried out using a human-relevant animal model, the marmoset monkey. First, uterine mRNA transcription and protein expression during the implantation phase in the conceptive and nonconceptive cycles were examined. Second, functional parameters were analyzed to assess the in vivo effects of exogenous applied relaxin throughout implantation. Relaxin and its receptor, RXFP1, were highly upregulated shortly before and during the physical process of implantation, indicating that relaxin is an important factor for remodeling and immunotolerance. The action of relaxin on the uterus was accompanied by an increase of estrogen-associated factors and macrophage infiltration, suggesting redundant systems necessary for successful implantation. The data from relaxin-treated animals supported those obtained from naive tissues in terms of increases in angiogenesis as well as earlier and faster growth of the uterus and placenta in the relaxin-treated marmoset monkey group, resulting in parturition 7-10 days earlier than the control group, but not pathological. In general, relaxin is very effective in preparing the endometrium for implantation. These findings should encourage further clinical research regarding introducing relaxin for pathological pregnancies, such as early pregnancy failure or insufficient placenta.

Recombinant human relaxin was used to attempt cervical ripening in post-delivery date pregnancies. High doses of relaxin were safe but did not advance cervical ripening or induce labor.

Relaxin is upregulated and plays a compensatory role in human heart failure. We therefore determined the safety of and dose response to human relaxin in stable patients with heart failure. Sixteen patients were treated with open-label intravenous relaxin in three sequential dose cohorts and monitored hemodynamically during the 24-h infusion and postinfusion periods. The safety demonstrated in group A (treatment for 8 h each with dosages equivalent to 10, 30, and 100 microg/kg/day) allowed escalation to group B (240, 480, and 960 microg/kg/day), and the highest safe dose, 960 microg/kg/day, was selected for a 24-h dosing in group C. Relaxin showed no relevant adverse effects and produced hemodynamic effects consistent with systemic vasodilation, i.e., trends toward increases in the cardiac index and decreases in pulmonary wedge pressure, without inducing hypotension. The first therapeutic use of relaxin in human heart failure demonstrated favorable hemodynamic effects and indicated that it may be of value in the treatment of this widespread disease.

Summary Background Most patients admitted for acute heart failure have normal or increase blood pressure. Relaxin is a natural human peptide that affects multiple vascular control pathways, suggesting potential mechanisms of benefit for such patients. We assessed the dose response of relaxin's effect on symptom relief, other clinical outcomes, and safety. Methods In a placebo-controlled, parallel-group, dose-ranging study, 234 patients with acute heart failure, dyspnoea, congestion on chest radiograph, and increased brain natriuretic peptide (BNP) or N-terminal prohormone of BNP, mild-to-moderate renal insufficiency, and systolic blood pressure greater than 125 mm Hg were recruited from 54 sites in eight countries and enrolled within 16 h of presentation. Patients were randomly assigned, in a double-blind manner via a telephone-based interactive voice response system, to standard care plus 48-h intravenous infusion of placebo (n=62) or relaxin 10 μg/kg (n=40), 30 μg/kg (n=43), 100 μg/kg (n=39), or 250 μg/kg (n=50) per day. Several clinical endpoints were explored to assess whether intravenous relaxin should be pursued in larger studies of acute heart failure, to identify an optimum dose, and to help to assess endpoint selection and power calculations. Analysis was by modified intention to treat. This study is registered with ClinicalTrials.gov, number NCT00520806. Findings In the modified intention-to-treat population, 61 patients were assessed in the placebo group, 40 in the relaxin 10 μg/kg per day group, 42 in the relaxin 30 μg/kg per day group, 37 in the relaxin 100 μg/kg per day group, and 49 in the relaxin 250 μg/kg per day group. Dyspnoea improved with relaxin 30 μg/kg compared with placebo, as assessed by Likert scale (17 of 42 patients [40%] moderately or markedly improved at 6 h, 12 h, and 24 h vs 14 of 61 [23%]; p=0·044) and visual analogue scale through day 14 (8214 mm×h [SD 8712] vs 4622 mm×h [9003]; p=0·053). Length of stay was 10·2 days (SD 6·1) for relaxin-treated patients versus 12·0 days (7·3) for those given placebo, and days alive out of hospital were 47·9 (10·1) versus 44·2 (14·2). Cardiovascular death or readmission due to heart or renal failure at day 60 was reduced with relaxin (2·6% [95% CI 0·4–16·8] vs 17·2% [9·6–29·6]; p=0·053). The number of serious adverse events was similar between groups. Interpretation When given to patients with acute heart failure and normal-to-increased blood pressure, relaxin was associated with favourable relief of dyspnoea and other clinical outcomes, with acceptable safety. Funding Corthera (USA).

Nonclinical studies indicate that the hormone relaxin is a good candidate for a safe cervical ripening agent that does not cause uterine contractions. This Phase II study (conducted November 2, 2005–October 20, 2006) was a randomised, double blind, placebo controlled trial testing 24-h intravenous infusion of serelaxin (recombinant human relaxin) or placebo for cervical ripening in 72 healthy, primiparous women. Eligible subjects had a singleton pregnancy ≥40 weeks, were planned for elective induction, had vertex presentation of the fetus, intact membranes and a Bishop score at screening ≤4. In Part A of the study, safety evaluation of three escalating doses of serelaxin (7.5, 25 or 75 μg/kg/day) or placebo was performed in 22 subjects admitted to the hospital 24 h prior to scheduled induction (n = 7, 4, 4, and 7 subjects, respectively). The highest safe dose from Part A and placebo were then tested in Part B for safety and cervical ripening (n = 25 subjects/arm). Planned randomisation ratio was of 4:2 (serelaxin:placebo) for each dose group in Part A and 1:1 for Part B. For analysis, subjects in Part B were pooled with those receiving the same dose in Part A and all subjects receiving placebo were pooled. The primary efficacy endpoint was change from baseline in Bishop score at 6, 12 and 24 h or end of study drug administration. Maternal safety evaluations included adverse events and vital signs through 4 weeks. Fetal assessments included serial heart rate monitoring and nonstress testing. Neonatal assessments included Apgar scores, NICU admissions, and adverse events through 4 weeks. Overall, 74 subjects were randomized and 72 were treated. There were no significant differences between the groups receiving the highest safe dose of serelaxin (75 μg/kg/day) and placebo in the primary or secondary efficacy endpoints. Changes from baseline in Bishop score at 24 h were 4.19 ± 1.9 and 3.26 ± 2.26 in the pooled placebo and serelaxin groups, respectively (p = 0.2507). Serelaxin was well tolerated and no anti-serelaxin antibodies were detected in either subjects or neonates. Serelaxin infusion at the end of pregnancy was well tolerated but did not advance cervical ripening. Clinicaltrials.gov identifier NCT00259103 (15 November 2005).

Fibronectin, a large adhesive glycoprotein, is a prominent constituent of the extracellular matrix. Abnormalities in fibronectin homeostasis occur in numerous disease states, ranging from primary fibrosing conditions to neoplastic transformation. We demonstrate that fibronectin is a target protein substrate for ubiquitin-dependent degradation. Coimmunoprecipitation experiments and confocal microscopy demonstrated ubiquitin-fibronectin interaction. In an in vitro model of renal fibrosis, relaxin, an insulin-like growth factor, increased ubiquitin-dependent fibronectin degradation. Relaxin also was evaluated in an anti-glomerular basement membrane model of renal fibrosis. Animals treated with relaxin experienced renoprotection, manifested by decreased serum creatinine and proteinuria. Histological evaluation of kidney sections from animals treated with relaxin showed decreased glomerulosclerosis and interstitial fibrosis. We conclude that relaxin might be developed as a useful agent for the treatment of renal fibrosis.