DNA-Encoded Library-Derived DDR1 Inhibitor Prevents Fibrosis and Renal Function Loss in a Genetic Mouse Model of Alport Syndrome

Abstract

The importance of Discoidin Domain Receptor 1 (DDR1) in renal fibrosis has been shown via gene knockout and use of antisense oligonucleotides; however, these techniques act via a reduction of DDR1 protein, while we prove the therapeutic potential of inhibiting DDR1 phosphorylation with a small molecule. To date, efforts to generate a selective small-molecule to specifically modulate the activity of DDR1 in an in vivo model have been unsuccessful. We performed parallel DNA encoded library screens against DDR1 and DDR2, and discovered a chemical series that is highly selective for DDR1 over DDR2. Structure-guided optimization efforts yielded the potent DDR1 inhibitor 2.45, which possesses excellent kinome selectivity (including 64-fold selectivity over DDR2 in a biochemical assay), a clean in vitro safety profile, and favorable pharmacokinetic and physicochemical properties. As desired, compound 2.45 modulates DDR1 phosphorylation in vitro as well as prevents collagen-induced activation of renal epithelial cells expressing DDR1. Compound 2.45 preserves renal function and reduces tissue damage in Col4a3 –/– mice (the preclinical mouse model of Alport syndrome) when employing a therapeutic dosing regime, indicating the real therapeutic value of selectively inhibiting DDR1 phosphorylation in vivo. Our results may have wider significance as Col4a3 –/– mice also represent a model for chronic kidney disease, a disease which affects 10% of the global population.

Bedside to bench Alport syndrome research: are human urine‐derived podocytes the answer?†

“…Loss of podocytes was reported as a very early change in kidney biopsies from patients born with AS [8]. Therefore, understanding the molecular pathways that are activated in podocytes detaching from an altered GBM would allow for the identification of new drugs that, although not disease-modifying, may restore GBM-podocyte interaction and delay disease progression, similar to what we have demonstrated by targeting the discoidin-domain receptor 1 [9].…”

Discoidin domain receptor 1 activation links extracellular matrix to podocyte lipotoxicity in Alport syndrome

“…This aberrant collagen network in the GBM is insufficient to preserve kidney function and is associated with the development of hematuria, proteinuria and renal failure early in life[ 25 , 26 ]. Furthermore, de novo production of Collagen type I α1 (Col1A1) and α2 chains (Col1A2) in the GBM at both transcriptional and translational level, has been observed in Col4a3KO mice and in AS patients [27] , [28] , [29] .…”

“…Activation of DDR1 by collagens has been shown to promote fibrosis and inflammation, generating a positive feedback loop that perpetuates DDR1 activation [ 37 , 41 ]. Interestingly, deletion of DDR1 in Col4a3KO mice was shown to improve renal function and survival [12] , and we recently reported that treatment of Col4a3KO mice with a selective DDR1 inhibitor improves renal function and fibrosis [29] . However, the mechanism(s) by which DDR1 activation by aberrant Col I production contributes to podocyte injury in AS remains elusive.…”

Basement membrane collagens and disease mechanisms

“…While the above approaches target the intracellular consequences, due to our relatively poor understanding of the matrix defects and the subsequent aberrant matrix–cell signalling, limited progress has been made. An emerging example is the pharmacological inhibition of DDR1 to preserve renal function and reduce renal fibrosis in Col4a3 −/− mice [157], illustrating the potential power of this approach.…”