黄斑变性
生物标志物
iC3b公司
补体因子B
补体因子I
系数H
医学
一致性
内科学
眼科
肿瘤科
补体系统
化学
免疫学
抗体
生物化学
作者
Thomas M Hallam,Emanuela Gardenal,Fraser McBlane,GaEun Cho,Lucy Lee Ferraro,Eva Pekle,Darlene Lu,Kate Carney,Claire Wenden,Hannah Beadsmoore,Sérgio Kaiser,Lauren Drage,Thomas Haye,Iris S. Kassem,Nalini Rangaswamy,Ma’en Obeidat,Cyndy Grosskreutz,Magali Saint‐Geniez,David Steel,Robert E. MacLaren
出处
期刊:Cold Spring Harbor Laboratory - medRxiv
日期:2024-06-13
标识
DOI:10.1101/2024.06.12.24308796
摘要
Abstract Objective Complement biomarker analysis in ocular fluid samples from subjects with geographic atrophy (GA) in a Phase I/II clinical trial of subretinal AAV2 complement factor I ( CFI ; FI) gene therapy, PPY988 (formerly GT005), to understand target pharmacokinetics/pharmacodynamics. Clinical findings were subsequently utilized to investigate the therapeutic dose in an in vitro complement activation assay. Design, setting and participants Biomarker data were evaluated from 28 subjects in FOCUS, a Phase I/II clinical trial evaluating the safety and efficacy of three ascending doses of PPY988. Main outcomes and measures Vitreous humor (VH), and aqueous humor (AH) from subjects before surgery and at serial timepoints (week 5 or 12, 36, 96) were evaluated for changes in levels of intact complement factors I, B and H (FI, FB, FH) components C3, C4, and C1q and breakdown products (Ba, C3a, C3b/iC3b, C4b) using validated assays and OLINK ® proteomics. A modified in vitro assay of complement activation modelling VH complement concentrations was used to compare PPY988 potency to the approved intravitreal C3 inhibitor pegcetacoplan (Apellis) and complement Factor H (FH). Results An average 2-fold increase in VH FI was observed post-treatment at week 36 and week 96. This correlated with a marked post-treatment reduction in VH concentration of the FB breakdown product Ba and Ba:FB ratio, but minimal changes in C3a and C3b/iC3b levels. Variable concordance in complement biomarker levels in VH versus AH suggest AH is not a reliable proxy for VH for complement activation. During the experimental comparison of doses, a 2-fold increase of FI achieved in the vitreous had only a minor effect on the complement amplification loop in vitro , indicating limited impact [IC50: 1229nM]. Pegcetacoplan completely blocks C3a generation at concentrations much lower than the estimated trough level for monthly intravitreal injections [IC50: 2nM]. Supplementation with FH in the assay revealed similar potency to pegcetacoplan [IC50: 6nM]. Conclusions and relevance PPY988 subretinal gene therapy may not have provided sufficient FI protein to meaningfully modulate complement activation to slow GA growth. Reviewing VH biomarkers is important for understanding target expression, pathway engagement, and determining optimal dose, thereby informing future clinical development.