XRF-1021 is an orally active HIPK2 inhibitor with an IC50 value of 0.18 μM. It reduces the expression of fibrosis markers such as fibronectin, type I collagen, and α-SMA in NRK-49F and HK-2 cells stimulated by TGF-β1. XRF-1021 blocks signaling pathways including TGF-β, NF-κB, p53, Wnt/β-catenin, and Notch. Additionally, it alleviates renal injury and fibrosis in vivo and can be utilized for research in chronic kidney disease.

HIPK2:0.18 μM

XRF-1021, at concentrations of (3-100 μM, 48 h), inhibits TGF-β1-induced proliferation of NRK-49F cells with an IC₅₀ of 4.87 μM, suggesting possible regulation of the HIPK2-mediated signaling pathway. At (100 μM, 24 h), XRF-1021 binds directly to HIPK2 with high binding stability (RMSD around 0.1 Å, RMSF < 0.1 Å). At (2.5-80 μM, 24 h), concentrations of 2.5, 5, and 10 μM show no significant effect on the proliferation or viability of HK-2 cells. XRF-1021 (2.5-10 μM, 24 h) inhibits HIPK2 and downstream signaling pathways, reducing fibrosis in HK-2 cells. Furthermore, it decreases the expression of HIPK2, FN, and α-SMA proteins in NRK-49F cells at the same concentrations and duration.

XRF-1021, administered orally at doses of 25-75 mg/kg, inhibits the expression of fibrotic markers by targeting HIPK2 and its downstream pathways, such as TGF-β, NF-κB, p53, Wnt/β-catenin, and Notch pathways, to mitigate kidney fibrosis progression in Sprague-Dawley (SD) rats with a UUO model. Additionally, XRF-1021, in doses of 25-100 mg/kg orally, alleviates tubular damage, reduces interstitial fibrosis, and enhances renal function in a C57BL/6J mouse model induced by an adenine diet by inhibiting HIPK2 and associated pro-fibrotic signaling pathways, including TGF-β, NF-κB, p53, Wnt/β-catenin, and Notch pathways.