#1003 Safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple ascending doses of AZD2373, an antisense oligonucleotide targeting APOL1

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Abstract
Background and Aims: APOL1 mediated kidney disease (AMKD) is associated with toxic gain of function variants in people of African ancestry carrying the high-risk APOL1 genotypes (G1 and G2). APOL1 protein is part of the innate immune system but not considered essential. AZD2373, an antisense oligonucleotide that targets APOL1 mRNA to reduce its protein synthesis, is in development for AMKD. In genomic APOL1-transgenic mice, AZD2373 reduced APOL1 expression in kidney and liver, reduced plasma APOL1 protein concentration, and prevented development of IFN-γ induced proteinuria in high-risk genotype mice. In a single ascending dose study (NCT04269031), AZD2373 was well tolerated. We assessed the safety and tolerability of AZD2373 in a multiple ascending dose study including pharmacokinetics, and pharmacodynamic effect on APOL1 plasma protein levels. Method: In this phase 1, randomized, single-blind, placebo-controlled study (NCT05351047) in healthy male volunteers of West African ancestry, participants were enrolled after a pre-screening study where they were genotyped for APOL1 prospectively; 18 participants had either 1 copy or 2 copies of the G1/G2 APOL1 high-risk allele. Low, medium and high dose cohorts each with 8 participants each receiving six weekly subcutaneous injections of either AZD2373 (n = 6) or placebo (n = 2) and were subsequently followed up for 9-weeks post-last dose. The primary objective was safety and tolerability; secondary objectives included assessment of pharmacokinetics and pharmacodynamics of AZD2373. Results: In total, 24 participants were randomized and completed the study. No major safety and tolerability concerns were reported up to the highest dose of AZD2373 administered. The most common adverse event was injection site reactions which were dose-dependent, mild to moderate in severity and did not lead to treatment discontinuation. After dosing, AZD2373 had a rapid distribution phase (hours) and prolonged elimination phase (days to weeks). Clearance was similar across dose levels after single and repeated dosing, and the renal contribution to overall clearance was minimal. Exposure generally increased in a dose proportional manner. Plasma APOL1 was knocked down in a dose dependent manner (Figure). Conclusion: Repeated doses of AZD2373 were safe and well tolerated, reducing plasma APOL1 concentrations in a dose- and time-dependent manner in healthy males of West African ancestry.