#5399 VONAFEXOR AS A NOVEL THERAPY FOR CHRONIC KIDNEY DISEASE
Authors: Yang Jiufang , Vasseur Florence , Burtin Martine , Nguyen Clement , Pelosi Michele , Garbay Serge , Mallinjoud Pierre , De Chassey Benoit , Vonderscher Jacky , Dartell Raphael , Pontoglio Marco , Terzi Fabiola 
Published: June 2023

Abstract

Background and Aims
Chronic kidney diseases (CKD) are characterized by the progressive loss of renal function. The molecular mechanisms underlying this progression are still poorly characterized and probably multifactorial. Therefore, there is a real need to expand the very limited number of therapies able to slow down the rate of CKD progression. Recent findings indicate that NR1H4, a druggable nuclear receptor, might play an important role in CKD. The aim of this study was to investigate the benefit of Vonafexor, a novel small molecule and specific NR1H4 agonist in acquired and genetic models of CKD.

Method
Two complementary experimental models of CKD (the 75% excision of total renal mass (Subtotal Nephrectomy; Nx) and the Col4a3−/− mice, a model of Alport disease) were studied. NR1H4 and the expression of some of its downstream targets were evaluated by quantitative RT-PCR, western blot and immunohistochemistry. In the Nx model, mice were treated with Vonafexor by daily oral gavage from 5 to 8 weeks after the surgery. The possible beneficial effect was compared to that of Losartan and other NR1H4 agonists. In the Alport model, mice were treated by Vonafexor from 5 to 8 weeks after birth. In both models, group of mice were sacrificed at 5 weeks to evaluate the extent of renal lesions at baseline. Renal lesions were quantified using image J. Renal inflammation, myofibroblast activation and podocyte number were quantified after specific staining. Human biopsies were also studied. RNAseq was performed using Illumina NovaSeq6000.

Results
We observed that NR1H4 expression and OSTA and OSTB, two downstream targets of NR1H4, were significantly reduced in remnant kidneys of Nx FVB/N mice compared to sham-operated animals 8 weeks after surgery. Co-localization staining revealed that NR1H4 is mainly expressed in proximal tubules and, to a minor extent, in Henle loops. Renal lesions were already present at 5 weeks in both experimental models. Remarkably, Vonafexor stopped the progression of renal lesions, in terms of glomerulosclerosis and tubular dilatations and, more importantly, induced a regression of interstitial fibrosis 8 weeks after nephrectomy as compared to the 5-week baseline. Lymphocytes and macrophage infiltration, as well as activated myofibroblasts, were also significantly reduced. Similarly, podocyte loss was stopped by Vonafexor treatment. Of note, the beneficial effect of Vonafexor was unique compared to other classes of NR1H4 agonists and also higher than that of Losartan. The same beneficial curative effect was found in Col4a3−/− mice. RT-PCR confirmed the activation of several NR1H4 downstream targets in mice treated with Vonafexor, while RNAseq analysis revealed that Vonafexor impacted the pathological activation of pathways involved in cell cycle, cell signaling and metabolism. These results may be relevant to humans, since NR1H4 expression was significantly reduced in biopsies from patients with CKD of different etiologies as compared to control kidneys.

Conclusion
Altogether our results identified in Vonafexor a novel key drug to control CKD. This is consistent with recent results obtained in LIVIFY phase 2 clinical trial in which Vonafexor has already demonstrated beneficial effects on eGFR in NASH patients with mild to moderate CKD.