Characterization of a new potent and long-lasting single chain peptide agonist of RXFP1 in cells and in vivo translational models

Abstract

Despite beneficial effects in acute heart failure, the full therapeutic potential of recombinant relaxin-2 has been hampered by its short half-life and the need for intravenous administration limiting its use to intensive care units. A multiparametric optimization of the relaxin B-chain led to the identification of single chain lipidated peptide agonists of RXFP1 like SA10SC-RLX with subcutaneous bioavailability and extended half-life. SA10SC-RLX has sub nanomolar activity on cells expressing human RXFP1 and molecular modeling associated with the study of different RXFP1 mutants was used to decipher the mechanism of SA10SC-RLX interaction with RXFP1. Telemetry was performed in rat where SA10SC-RLX was able to engage RXFP1 after subcutaneous administration without tachyphylaxis after repeated dosing. Renal blood flow was then used as a translational model to evaluate RXFP1 activation. SA10SC-RLX increased renal blood flow and decreased renal vascular resistance in rats as reported for relaxin in humans. In conclusion, SA10SC-RLX mimics relaxin activity in in vitro and in vivo models of acute RXFP1 engagement. SA10SC-RLX represents a new class of long-lasting RXFP1 agonist, suitable for once daily subcutaneous administration in patients and potentially paving the way to new treatments for chronic fibrotic and cardiovascular diseases.

R2R01: A long‐acting single‐chain peptide agonist of RXFP1 for renal and cardiovascular diseases

“…This method has been consistently used in our different research programmes. The n = 5 was the minimum of animals required by the BJP to make a statistical analysis and we knew from previous telemetry studies (Illiano et al, 2022) that this will be sufficient regarding the potency of R2R01. For nipple length, the number of animals was designed based on a previous study to give us sufficient statistical power to detect early changes (1 week) and was kept for subsequent studies.…”

“…Biostatisticians performed sample size estimations for this model based on previous internal data using suitable statistical tests, for which significance is obtained at fixed difference of interest (in a range of 20% to 50%), power (usually 80%), and alpha risk (usually 0.05), which depends on the models and the readouts. For RBF, the number of animals to reach statistical significance was also selected based on previous experiences with this assay with similar peptides (Illiano et al, 2022). ANOVA and post-hoc test analyses were performed after confirming the hypothesis of normality and homogeneity of variance.…”

Seleno-relaxin analogues: effect of internal and external diselenide bonds on the foldability and a fibrosis-related factor of endometriotic stromal cells

“…[7][8][9][10][11][12][13] Although a recent clinical trial (Novartis; second phase III) 14 found no significant effect of H2 relaxin on the treatment of acute heart failure, there is still a great deal of interest in H2 relaxin's pharmacological applications. Several research institutions, including pharmaceutical companies, have developed a variety of H2 relaxin-related formulation candidates, such as long-acting relaxins 15,16 , single-chain relaxin mimics [17][18][19] , and small molecular RXFP1 agonists 20,21 , and some of which are undergoing clinical trials. Endometriosis, which affects approximately 5-10% of women of childbearing age, induces dysmenorrhea, dyspareunia, and dyschezia, substantially compromising patients' quality of life.…”

Further Developments towards a Minimal Potent Derivative of Human Relaxin-2

“…Importantly, unlike H2 relaxin, B7-33 did not exacerbate prostate tumor growth in mice, which is postulated to be a cAMP-mediated side-effect [ 13 ]. More recently, stabilized variants of B7-33 have been reported by the pharmaceutical company, Sanofi [ 20 , 21 ]. While these analogs are shown to be long-acting in vivo, they regained cAMP potency, similar to H2 relaxin, that could have detrimental effects (such as tumor growth and increased heart rate).…”