PO.ET09.08 · 实验与分子治疗
通过EO-4426双重DNA复制靶向克服胞苷脱氨酶（CDA）介导的耐药：对CDA高表达实体瘤和间充质型GBM的意义
Overcoming cytidine deaminase (CDA) mediated resistance via EO-4426 dual DNA-replication targeting: Implications for CDA-high solid tumors and mesenchymal GBM
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：EO-4426（tezacitabine）是一种可穿透脑组织、抗脱氨基的胞苷类似物，其独特地同时抑制DNA聚合酶-α（Polα）和核糖核苷酸还原酶（RNR），从而导致dNTP池耗竭、复制叉崩溃以及在快速增殖的肿瘤细胞中DNA损伤累积。与gemcitabine和hydroxyurea不同，EO-4426能够抵抗胞苷脱氨酶（CDA）介导的失活。CDA高表达或具有APOBEC3G相关胞苷代谢活性的肿瘤——包括间充质型GBM、TNBC、NSCLC和卵巢癌——预期会对Polα/RNR功能表现出更高的依赖性，因此可能对双重靶向策略特别敏感。
方法：正在进行的体外研究正在多种工程化及天然CDA高表达癌细胞模型中评估EO-4426，以确定其机制药理学和生物标志物富集假说。实验方法包括：(i) 通过LCMS定量EO-4426诱导的dNTP池耗竭；(ii) 通过免疫印迹和高内涵成像评估复制应激和DNA损伤生物标志物（γH2AX、pRPA32、pCHK1）；(iii) 表征APOBEC3G→CDA通路活性及其对药物敏感性的影响；(iv) 通过流式细胞术分析S期停滞和复制叉扰动；以及 (v) 与电离辐射和DDR靶向药物（包括ATR抑制）的联合研究。
初步发现：既往非临床研究表明，EO-4426在CDA高表达的肿瘤环境中保持强效活性，且不易被快速脱氨基，从而区别于gemcitabine（后者可被高效转化为无活性的dFdU）。已发表的研究还报道了其与DNA导向药物和氟嘧啶联合使用时增强的抗肿瘤活性，这与强效的复制应激诱导和dNTP耗竭生物学特性相一致。在临床上，EO-4426已在多项第三方申办的I/II期试验中接受评估，显示可预测的骨髓抑制为主要毒性，并在既往接受过大量治疗的实体瘤人群中表现出抗肿瘤活性的证据，包括客观缓解和持久的疾病稳定。
结论：目前正在开发新的数据，以支持在胞苷代谢驱动的肿瘤背景下对EO-4426的进一步研究，以及针对CDA高表达实体瘤和间充质型/APOBEC3G富集型GBM的生物标志物指导的临床开发策略。全面的体外机制数据、生物标志物相关性以及联合治疗结果将在本次会议上呈现。
查看英文原文 English abstract
Background: EO-4426 (tezacitabine) is a brain-penetrant, deamination-resistant cytidine analog that uniquely inhibits both DNA polymerase-alpha (Polalpha) and ribonucleotide reductase (RNR), leading to dNTP-pool depletion, replication-fork collapse, and DNA-damage accumulation in rapidly proliferating tumor cells. Unlike gemcitabine and hydroxyurea, EO-4426 resists cytidine deaminase (CDA)-mediated inactivation. Tumors with high CDA expression or APOBEC3G-linked cytidine-metabolism activity-including mesenchymal GBM, TNBC, NSCLC, and ovarian cancer-are predicted to exhibit heightened dependence on Polalpha/RNR function and may therefore be particularly susceptible to dual-targeting strategies.
Methods: Ongoing invitro studies are assessing EO-4426 across engineered and naturally CDA-high cancer cell models to define mechanistic pharmacology and biomarker-enrichment hypotheses. Experimental approaches include: (i) LCMS quantification of EO-4426-induced dNTP-pool depletion; (ii) evaluation of replication-stress and DNA-damage biomarkers (gammaH2AX, pRPA32, pCHK1) by immunoblot and high-content imaging; (iii) characterization of APOBEC3G→CDA pathway activity and its impact on drug sensitivity; (iv) flow cytometric analysis of S-phase arrest and replication-fork perturbation; and (v) combinatorial studies with ionizing radiation and DDR-targeting agents, including ATR inhibition.
Preliminary Findings: Prior nonclinical studies demonstrate that EO4426 retains potent activity in CDA-high tumor environments and is not susceptible to rapid deamination, distinguishing it from gemcitabine, which is efficiently converted to inactive dFdU. Published work also reports enhanced antitumor activity in combination with DNA-directed agents and fluoropyrimidines, consistent with strong replication-stress induction and dNTP-depletion biology. Clinically, EO4426 has been evaluated in multiple third-party sponsored Phase I/II trials, showing predictable myelosuppression as the principal toxicity and evidence of antitumor activity, including objective responses and durable disease stabilization, in heavily pretreated solid-tumor populations.
Conclusions: New data are being developed to support further investigation of EO-4426 in cytidine metabolism-driven tumor contexts and biomarker guided clinical development strategies for CDA-high solid tumors and mesenchymal/APOBEC3G-enriched GBM. Comprehensive in vitro mechanistic data, biomarker correlations, and combination treatment findings will be presented at the Meeting.
利益披露 Disclosure
J. Bacha,
Edison Oncology Holding Corp. Employment, g., Board of Directors, non-salaried role), Stock, Stock Option, Other Securities, Travel, Patent.
Rakovina Therapeutics Inc. g., Board of Directors, non-salaried role), Independent Contractor, Stock, Stock Option, Travel, Patent.
Sera Biopharma Inc. g., Board of Directors, non-salaried role), Independent Contractor, Stock, Stock Option.
D. M. Brown,
Edison Oncology Holding Corp. g., Board of Directors, non-salaried role), Independent Contractor, Stock, Stock Option.
Rakovina Therapeutics Inc. g., Board of Directors, non-salaried role), Stock, Stock Option.
R. Daniels,
Edison Oncology Holding Corp. g., Board of Directors, non-salaried role), Independent Contractor.
J. Langlands,
Rakovina Therapeutics Inc. g., Board of Directors, non-salaried role), Independent Contractor, Stock, Stock Option.