#2426 Exploration of cagrilintide's mechanism of action in the kidney

Abstract Background and Aims The hormone amylin, co-secreted with insulin from the beta-cells of the pancreas, induces satiety. Previous studies have highlighted a physiological role of amylin in glucose/sodium homeostasis and blood pressure regulation. However, in states of (pre)diabetes, amylin deposits have been described in the kidneys and other organs. Cagrilintide, a long-acting amylin analogue, which binds to both calcitonin and amylin receptors (G-protein-coupled receptors), has demonstrated a dose-dependent and clinically significant effect on weight loss in humans. Despite this, the kidney-specific metabolic pathways affected by amylin agonism remain poorly understood. To address this gap, we investigated cagrilintide's mechanism of action in the kidneys of healthy and diabetic Zucker Diabetic Fatty (ZDF) rats using an ex vivo approach. Method For a total of 20 fasted, male ZDF rats, 13 to 15 weeks in age (10 obese/diabetic and 10 lean/healthy), one third of a kidney was reserved for histological evaluation, while the remaining tissue underwent enzymatical digestion into cortical and medullary tubule fractions. Tubules were exposed to a phosphodiesterase inhibitor (IBMX 0.5 mM, 15 minutes) and then treated with vehicle, cagrilintide (1 µM), or salmon calcitonin (1 µM) for 30 minutes. Intracellular cyclic AMP (cAMP) levels were quantified using a commercially available detection kit (HTRF cAMP Gi Detection Kit, Revvity). Residual tubular samples were snap-frozen for subsequent phosphoproteomic analyses. Results In healthy rat tubules, cagrilintide treatment induced phosphorylation of ion transporters in the thick ascending limb of the loop of Henle (TAL) and the distal convoluted tubule (e.g., NKCC2 and NCC), while also modifying mTOR regulators. Obese ZDF rats proved to be diabetic with a mean HbA1c of 7.2% (4.0% in healthy rats; P < 0.0001). In addition, diabetic ZDF rats showed evidence of diabetic nephropathy, characterized by glomerular hyperfiltration (as evaluated by plasma creatinine levels) and severely increased albuminuria (mean 18682 µg/mg vs. 52 µg/mg in healthy rats). In these diabetic ZDF rats, cagrilintide significantly increased intracellular cAMP levels in cortical tubules (P = 0.00055; t-test vs. vehicle). In contrast, healthy rats showed no significant cAMP response to cagrilintide. Preliminary findings suggest that the distal nephron in diabetic rats may be more responsive to cagrilintide. Phosphoproteomic measurements are ongoing and expected to reveal downstream signaling alterations modulated by cagrilintide in both cortical and medullary nephron segments. Conclusion Our results point to a diabetes-specific mechanism by which cagrilintide elevates cAMP in cortical tubules, providing initial evidence of mode of action in diabetic kidney physiology compared with healthy controls. Ongoing phosphoproteomic analyses will offer deeper insights into the molecular pathways affected, potentially guiding the therapeutic application of cagrilintide in diabetic kidney disease.