Targeted Enzymatic Fragmentation of Lipoprotein(a) via Kringle IV Domains: A Novel Therapeutic Approach for Cardiovascular Disease.

Abstract

BackgroundElevated lipoprotein(a) [Lp(a)] is an independent, genetically determined risk factor for atherosclerotic cardiovascular disease (ASCVD). Its unique apolipoprotein(a) [apo(a)] component contains variable Kringle IV (KIV) domain repeats that influence secretion, thrombosis, and atherogenesis. Current therapies antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs) suppress hepatic production and achieve up to 80-98% Lp(a) reduction. However, mechanisms for enhancing clearance remain underexplored. ObjectiveWe propose a biologic approach to actively accelerate Lp(a) removal. Specifically, we design an antibody-drug conjugate (ADC) that binds conserved KIV9/10 domains and delivers a protease to fragment apo(a) into kidney-excretable fragments, complementing existing production inhibitors. MethodsThe therapeutic is designed as a monoclonal antibody directed at KIV9/10 fused via a cleavable linker to a site-specific protease (e.g., IdeS-like) engineered for conditional activity. Kringle domains were modeled with graph neural networks trained on plasminogen homologs to predict epitope accessibility and binding affinity. A one-compartment, first-order elimination model was used to illustrate potential clearance acceleration, with normal Lp(a) clearance modeled at rate constant k = 0.05 h-1 enhanced clearance at k = 0.10 h-1 CKD at k=0.03 h-1 and CKD+enhanced at k=0.06 h-1. ResultsSimulated concentration-time curves showed that doubling the clearance rate could shorten Lp(a) half-life from [~]13.9 to [~]6.9 h (normal vs. enhanced) and from [~]23.1 to [~]11.6 h (CKD vs. CKD+enhanced). Starting at 100 mg/dL, normal clearance reached [~]9.07 mg/dL by 48 h, while enhanced reached [~]0.82 mg/dL; CKD reached [~]23.69 mg/dL, restored to [~]5.61 mg/dL with enhancement. Acute 50-70% lowering was predicted within 24 h, potentially enabling infrequent dosing and synergy with production inhibitors. ConclusionsEnzymatic fragmentation of Lp(a) at KIV domains is a novel clearance-enhancing paradigm. By generating <100 kDa fragments suitable for renal excretion, this strategy could complement ASO/siRNA therapies, particularly in patients with residual high Lp(a) or impaired kidney function. Further work should validate protease specificity, safety, and in vivo efficacy in animal models before clinical translation.