PO.ET02.01 · 实验与分子治疗
利用搭载多样化载荷的抗体偶联药物组合靶向MET-LGR5串扰以克服结直肠癌的适应性耐药
Targeting MET-LGR5 crosstalk using an antibody-drug conjugate combination with diverse payloads to overcome adaptive resistance in colorectal cancer
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摘要 Abstract
中文摘要
脱靶副作用和耐药性常常阻碍现有抗癌疗法针对结直肠癌(CRC)的治疗获益，CRC是全球第二致命的恶性肿瘤。CRC含有肿瘤起始性的类癌症干细胞(CSC)，其可在毒性药物中存活并引发转移性疾病。抗体偶联药物(ADC)是一类革命性的治疗药物，利用单克隆抗体(mAb)的特异性将细胞毒性载荷递送至肿瘤细胞。我们构建了靶向富含亮氨酸重复序列的G蛋白偶联受体5(LGR5)的ADC，LGR5是一个公认的CSC生物标志物，在CRC中常过表达。我们的LGR5 ADC在CRC异种移植模型中表现出高效力且毒性极小。然而，其未能阻止停药后的肿瘤复发。有趣的是，我们发现复发肿瘤通过短暂转变为LGR5阴性(LGR5⁻)状态来逃避LGR5 ADC介导的清除，同时伴随MET上调和下游通路的激活。MET是一种受体酪氨酸激酶，在CRC中常上调并促进转移进展。我们发现STAT3(MET通路中的一个下游效应蛋白)的激活削弱了LGR5 ADC在CRC细胞中的疗效。为清除耐药的LGR5⁻细胞，我们通过将高选择性MET mAb(ABT700)骨架与DNA交联载荷吡咯并苯二氮䓬(PBD)进行位点特异性偶联，构建了MET靶向ADC。这种MET ADC(ABT700-PBD)在CRC细胞中表现出剂量依赖性细胞毒性。此外，ABT700-PBD不影响经基因诱导MET敲除的CRC细胞，证明了其特异性。免疫功能健全小鼠的安全性研究显示ABT700-PBD具有良好的安全性特征。此外，在CRC异种移植模型中，ABT700-PBD诱导了显著的肿瘤消退。然而，在剂量依赖性ABT700-PBD单药治疗后的残余肿瘤中，LGR5蛋白表达上调。这些观察结果提示MET-LGR5串扰可能是CRC适应性耐药的潜在驱动因素。测试ABT700-PBD和我们此前报道的喜树碱衍生(CPT2)LGR5靶向ADC(8E11-CPT2)的细胞毒性试验在体外显示出协同杀伤活性。在CRC患者来源异种移植模型中，ABT700-PBD与8E11-CPT2的联合治疗相比单药ADC延长了生存期。总的来说，我们的研究结果支持MET和LGR5 ADC联合疗法作为克服CRC适应性耐药驱动复发的新型治疗策略。
查看英文原文 English abstract
Off-target side effects and drug resistance often hamper the therapeutic benefits of existing anti-cancer therapies against colorectal cancer (CRC), the second deadliest malignancy worldwide. CRCs contain tumor-initiating cancer stem-like cells (CSCs) that survive toxic drugs and give rise to metastatic disease. Antibody-drug conjugates (ADCs) are a revolutionary class of therapeutics that leverage monoclonal antibody (mAb) specificity to deliver cytotoxic payloads to tumor cells. We generated ADCs targeting leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), a bona fide CSC biomarker frequently overexpressed in CRCs. Our LGR5 ADC exhibited high potency in CRC xenograft models with minimal toxicity. However, it failed to prevent tumor relapse after treatment cessation. Interestingly, we found that recurrent tumors evade LGR5 ADC-mediated elimination by transiently converting into an LGR5-negative (LGR5 - ) state, accompanied by concomitant MET upregulation and activation of the downstream pathway. MET is a receptor tyrosine kinase frequently upregulated in CRCs and promotes metastatic progression. We identified that the activation of STAT3, a downstream effector protein in the MET pathway, undermines LGR5 ADC efficacy in CRC cells. To eliminate drug-resistant LGR5 - cells, we generated MET-targeted ADCs by attaching a highly selective MET mAb (ABT700) backbone to the DNA-crosslinking payload pyrrolobenzodiazepine (PBD) via site-specific conjugation. This MET ADC (ABT700-PBD) demonstrated dose-dependent cytotoxicity in CRC cells. Furthermore, ABT700-PBD did not affect CRC cells with genetically induced MET ablation, demonstrating its specificity. Safety studies in immunocompetent mice showed that ABT700-PBD exhibited a favorable safety profile. Moreover, in CRC xenograft models, ABT700-PBD induced marked tumor regression. However, in the residual tumors following dose-dependent ABT700-PBD monotherapy, LGR5 protein expression was upregulated. These observations suggest that the MET-LGR5 crosstalk may be a potential driver of adaptive resistance in CRC. Cytotoxicity assays testing ABT700-PBD and our previously reported camptothecin-derived (CPT2) LGR5-targeted ADC (8E11-CPT2) demonstrated synergistic cell-killing activity in vitro. Combination treatment with ABT700-PBD and 8E11-CPT2 in CRC patient-derived xenograft models extended survival compared to single-agent ADCs. Collectively, our findings support MET and LGR5 ADC combination therapy as a novel treatment strategy to overcome adaptive resistance-driven relapse in CRC.
利益披露 Disclosure
S. Subramanian, None.