Renal Hemodynamic Effects of Relaxin in Humans

Development of a long-acting relaxin analogue, LY3540378, for treatment of chronic heart failure

BACKGROUND AND PURPOSE

Chronic heart failure, a progressive disease with limited treatment options currently available, especially in heart failure with preserved ejection fraction (HFpEF), represents an unmet medical need as well as an economic burden. The development of a novel therapeutic to slow or reverse disease progression would be highly impactful to patients and society. Relaxin-2 (relaxin) is a human hormone regulating cardiovascular, renal, and pulmonary adaptations during pregnancy. A short-acting recombinant relaxin, Serelaxin, demonstrated short-term heart failure symptom relief and biomarker improvement in acute heart failure trials. Here, we present the development of a long-acting relaxin analogue to be tested in the treatment of chronic heart failure.

EXPERIMENTAL APPROACH

LY3540378 is a long-acting protein therapeutic composed of a human relaxin analogue and a serum albumin-binding VHH domain.

KEY RESULTS

LY3540378 is a potent agonist of the relaxin family peptide receptor 1 (RXFP1) and maintains selectivity against RXFP2/3/4 comparable to native relaxin. The half-life of LY3540378 in preclinical species is extended through high affinity binding of the albumin-binding VHH domain to serum albumin. When tested in a single dose administration, LY3540378 elicited relaxin-mediated pharmacodynamic responses, such as reduced serum osmolality and increased renal blood flow in rats. In an isoproterenol-induced cardiac hypertrophy mouse model, treatment with LY3540378 significantly reduced cardiac hypertrophy and improved isovolumetric relaxation time. In a monkey cardiovascular safety study, there were no adverse observations from administration of LY3540378.

CONCLUSION AND IMPLICATIONS

LY3540378 demonstrated to be a suitable clinical development candidate, and is progressing in clinical trials.

Relaxin-2 as a Potential Biomarker in Cardiovascular Diseases

The pleiotropic hormone relaxin-2 plays a pivotal role in the physiology and pathology of the cardiovascular system. Relaxin-2 exerts relevant regulatory functions in cardiovascular tissues through the specific receptor relaxin family peptide receptor 1 (RXFP1) in the regulation of cardiac metabolism; the induction of vasodilatation; the reversion of fibrosis and hypertrophy; the reduction of inflammation, oxidative stress, and apoptosis; and the stimulation of angiogenesis, with inotropic and chronotropic effects as well. Recent preclinical and clinical outcomes have encouraged the potential use of relaxin-2 (or its recombinant form, known as serelaxin) as a therapeutic strategy during cardiac injury and/or in patients suffering from different cardiovascular disarrangements, especially heart failure. Furthermore, relaxin-2 has been proposed as a promising biomarker of cardiovascular health and disease. In this review, we emphasize the relevance of the endogenous hormone relaxin-2 as a useful diagnostic biomarker in different backgrounds of cardiovascular pathology, such as heart failure, atrial fibrillation, myocardial infarction, ischemic heart disease, aortic valve disease, hypertension, and atherosclerosis, which could be relevant in daily clinical practice and could contribute to comprehending the specific role of relaxin-2 in cardiovascular diseases.

Influence of recombinant human relaxin on renal hemodynamics in healthy volunteers

Maternal renal hemodynamic adaptation to human pregnancy is one of the most dramatic of all physiologic changes, but the factors that are responsible have remained elusive. In rat pregnancy, there are comparable renal hemodynamic changes, and in this species there is comprehensive evidence that the ovarian hormone relaxin (RLX) is responsible. This study investigated the renal effects of recombinant human RLX (rhRLX) in humans. Eleven volunteers (six male, five female) received intravenous infusions of rhRLX over 5 h at an infusion rate that was chosen to sustain serum concentrations that are comparable to early pregnancy. The renal clearances of inulin and para-aminohippurate were used to measure GFR and renal plasma flow, respectively. Irrespective of gender, renal plasma flow was increased by 47% compared with baseline levels (P < 0.0001), but no significant change was observed in GFR. There were no side effects or adverse reactions of rhRLX given as an intravenous infusion, and the data suggest that RLX indeed may be one of the elusive renal vasodilatory factors in human pregnancy. Further work is necessary to elucidate the complimentary factors that permit the concomitant increase in GFR during pregnancy.