Small Molecule Inhibition of APOL1 Channel Activity Protects Podocytes from Mitochondrial Dysfunction, Cell Death, and Barrier Disruption Induced by APOL1 Risk Variants

Background: The presence of two copies of apoliprotein L1 (APOL1) genetic variants, APOL1 G1 or G2, along with a ‘second hit’ (IFNg, HIV, cytokines, etc.), can cause damage to specialized kidney cells called podocytes. We sought to examine the impact of APOL1 variants in podocytes and the potential impact inhibition of APOL1-mediated ion flux could have on these effects. Methods: To enable this effort, we developed tetracycline inducible, human immortalized podocyte lines expressing APOL1 G0 (reference allele), APOL1G1 or APOL1 G2 and examined cell survival following APOL1 induction using a cell death assay. We also studied the potential for APOL1 variants to disrupt cell adhesion, cell-cell junctions and mitochondrial function and the ability of APOL1 ion channel inhibition to modulate these effects. Results: APOL1 G1 and G2 induction led to a loss in podocyte viability that was rescued by treatment with Compound 3, a close analog of our clinical candidate inaxaplin. We also demonstrate that prophylactic inhibition of APOL1 prevents cell detachment and mitochondrial dysfunction and preserves podocyte barrier formation. Further, therapeutic administration of compound enabled restoration of these three outcomes, highlighting the potential to rescue damaged podocytes. Conclusion: These data highlight the critical importance of APOL1-mediated ion flux in APOL1 driven cell injury and suggest that damaged podocytes can be recovered to restore their critical filtration barrier. Funding: Commercial Support - Vertex Pharmaceuticals, inc.