Abstract Body: Introduction: Apelin is an endogenous myokine and exerkine with therapeutic relevance for PAD. Exogenous apelin induces endothelium-dependent vasorelaxation and exhibits anti-thrombotic, anti-atherosclerotic, and pro-angiogenic effects. Intrabrachial infusion of native apelin increased the forearm blood flow in humans, however, a half-life of only minutes is a barrier for its broad therapeutic use. We, therefore, developed a proprietary platform of long-acting apelin analogs optimized for treatment of PAD.
Methods: A novel peptide chemistry approach was dieveloped to improve proteolytic stability and plasma albumin binding. Agonistic activity towards the apelin receptor (APJ) and beta-arrestin were tested in stably transfected cells. Neutral pH solubility and stability in formulation buffer and multi-species plasma were determined by HPLC. PK parameters for IV and SC administration and acute tolerability were assessed in rats and dogs. Pro-angiogenic activity and muscle function were evaluated in a murine model of muscular dystrophy.
Results: VS-214 was selected for clinical development from a library of approx. 200 apelin peptide analogs differentiated by pharmaceutical properties, including extended half-lives in preclinical species, that are consistent with weekly or less frequent dosing in patients. In stably transfected cells, VS-214 demonstrated potent APJ receptor activation with G-protein biased signaling (cAMP EC₅₀ = 1.6 nM versus β-arrestin EC₅₀ = 12.1 nM). In line with a high interspecies homology, VS-214 showed comparable potency across human, dog, rat, and mouse APJ receptors. VS-214 remained stable in neutral formulation buffer for 14 days at 40°C, supporting the feasibility of autoinjector development. VS-214 exhibited >95% bioavailability in dogs, and terminal half-lives of 17.5 and 84.5 hrs following SC injection in rats and dogs, respectively. Allometric scaling predicts a human half-life of 3–5 days. VS-214 was well tolerated and maintained linear exposures up to 750 mg/kg in rats and 150 mg/kg in dogs. In a murine muscular dystrophy model, VS-214 significantly improved muscle force and treadmill endurance without inducing muscle hypertrophy, and increased VEGF mRNA expression, consistent with pro-angiogenic activity.
Conclusions: VS-214 is a first-in-class drug candidate for PAD with a half-life optimized for once-weekly SC administration and an exercise-mimicking pharmacology of native apelin. IND/CTA-enabling studies are ongoing.