SA-PO782 Poster Saturday CKD: Mechanisms - III
Apabetalone Downregulates Alkaline Phosphatase and Improves Cardiovascular Risk
Dean Gilham, 1 Laura Tsujikawa,1 Sylwia Wasiak,1 Christopher Halliday,1 Li Fu,1 Chris Sarsons,1 Phoebe S. Ho,1 Stephanie Stotz,1 Brooke D. Rakai,1 Kenneth E. Lebioda,1 Ravi Jahagirdar,1 Michael Sweeney,3 Jan O. Johansson,1 Norman C. Wong,1 Kamyar Kalantar-Zadeh,2 Mathias Haarhaus,4 Ewelina Kulikowski.1 1 Resverlogix, Calgary, AB, Canada; 2 University of California Irvine, School of Medicine, Orange, CA; 3 Resverlogix, San Francisco, CA; 4 Karolinska University Hospital, Stockholm, Sweden.
Background: Apabetalone is an inhibitor of BET proteins - epigenetic readers modulating gene expression. In phase 2 trials, apabetalone reduced major adverse cardiac events (MACE) in patients with cardiovascular disease (CVD) & improved eGFR in those with chronic kidney disease (CKD). Elevated serum alkaline phosphatase (ALP) is a risk factor for MACE, as it contributes to vascular calcification & endothelial dysfunction. We examined apabetalone-mediated effects on ALP in CVD patients post-hoc & determined apabetalone’s impact on tissue non-specific ALP (TNAP) expression in cell culture systems.
Methods: Circulating ALP was measured in CVD patients receiving apabetalone in the 3-month (ASSERT) and 6-month (SUSTAIN & ASSURE) trials. Apabetalone’s effect on expression of TNAP (gene symbol ALPL) was determined in cultured primary human hepatocytes (PHH), HepaRG, HepG2, calcifying vascular smooth muscle cells (VSMCs) & vascular endothelial cells. Protein abundance & ALP enzyme activity were also measured.
Results: In phase 2 trials, baseline serum ALP correlated with MACE (R2 =0.87). In ASSERT, apabetalone dose dependently reduced serum ALP (p<0.001 vs placebo). In ASSURE & SUSTAIN, patients on apabetalone (n=331) had greater reduction in serum ALP than placebo (n=166; median % change -3.2 vs -11; p<0.001), including those with CKD, i.e. eGFR<60 (apabetalone n=35 placebo n=13 median % change -6.3 vs -14; p<0.02). In vitro, apabetalone suppressed ALPL expression in PHH, HepaRG & HepG2 cells by 60-80%. Trans-differentiation of VSMCs to calcifying cells resulted in 2.5-fold increase in ALPL gene expression. Apabetalone countered calcium deposition & suppressed ALPL/TNAP gene expression, protein levels & enzyme activity. Apabetalone also downregulated ALPL in aortic endothelial cells, umbilical vein endothelial cells & brain microvascular endothelial cells 50-70%.
Conclusions: In phase 2 trials, apabetalone lowered serum ALP. Mechanistically, apabetalone downregulates ALPL/TNAP expression in multiple cell types, which may contribute to reductions in MACE observed in patients. The impact of apabetalone on biomarkers, renal function & CVD outcomes is being evaluated in the phase 3 BETonMACE trial. Funding: Commercial Support - Resverlogix