Base Editing (ABE8e) for PCSK9 c.399+1G>A in Coronary artery disease with genetically mediated dyslipidaemia (PCSK9/LDLR/LPA-driven)

Base Editing (ABE8e) via LNP delivery is a rationale-driven therapeutic strategy for Coronary artery disease with genetically mediated dyslipidaemia (PCSK9/LDLR/LPA-driven) targeting the PCSK9 c.399+1G>A variant (Likely pathogenic, splice donor variant, intron variant). The editing system (ABE8e-nSpCas9) corrects the splice-site point mutation to restore canonical splicing, as the underlying change is a single-nucleotide transition. Target tissue: Liver. Therapeutic goal: Permanently disrupt hepatic PCSK9 at Chr1:55505647 (GRCh38) to lower lifelong LDL-cholesterol and reduce coronary artery disease events, mimicking human PCSK9 loss-of-function protection.. Risk profile: off-target Medium, delivery complexity Low, immunogenicity Low.

1. Molecular basis: PCSK9 NM_174936.4(PCSK9):c.399+1G>A is classified as Likely pathogenic (ClinVar variation ID 4277664). Molecular consequence: splice donor variant, intron variant. 2. Epidemiology: Ischaemic heart disease, predominantly coronary artery disease (CAD), is the leading cause of death worldwide and accounts for ~23.5% of DALYs among non-communicable diseases; DALYs due to ischaemic heart disease increased by ~28% from 2005 to 2015 [PAPER-01]. Elevated lipoprotein(a) affects tens of 3. Standard of care: Guideline-directed therapy for CAD combines lifestyle modification, intensive lipid lowering (high-intensity statins with add-on ezetimibe and PCSK9-directed therapies), antiplatelet and antianginal medications, and coronary revascularisation by PCI with drug-eluting stents or CABG in appropriate an 4. Pipeline: Multiple late-stage RNA-based programs target coronary risk pathways. PCSK9 mAbs are approved with completed Phase III outcomes trials (FOURIER and others) showing ~15% relative MACE reduction over ~2 years [PAPER-05, PAPER-02], and inclisiran is approved based on durable ~50% LDL-C reduction with o 5. ABE clinical validation: ABE8e (Richter et al. 2020, Nat Biotechnol) achieves ~1.7x higher editing efficiency than ABE7.10. VERVE-101 demonstrated first-in-human LNP-ABE liver editing with 55-66% PCSK9 reduction (Raal et al. 2025, NEJM). Beam Therapeutics is advancing multiple ABE programs.

1. No published data specifically correcting PCSK9 c.399+1G>A with Base Editing (ABE8e); strategy is based on general principles and must be validated preclinically.
2. PAM availability and bystander base analysis for the specific genomic context have not been performed. If no canonical NGG PAM positions the target within the editing window, PAM-flexible variants (SpRY) may be needed.
3. Long-term durability, off-target genome-wide effects, and immunogenicity in the target patient population require thorough preclinical and clinical evaluation.