Background/Objectives: High-risk neuroblastoma patients are treated with approved anti-ganglioside GD2 antibodies of moderate (dinutuximab beta; DB) and higher binding affinity (naxitamab; NAXI). We evaluated the functional potency of DB compared to NAXI and investigated the target-mediated drug disposition (TMDD). Methods: Tumor spheroids were generated from neuroblastoma cells with varying GD2 expression, stably expressing iRFP680 as a viability marker. Antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) were assessed in a long-term life-cell viability assay using serial dilutions of the GD2 antibodies. Binding activity was determined by flow cytometry. Processes involved in TMDD were analyzed, including antibody binding to dead tumor cells and to soluble GD2 (sGD2), antibody internalization into tumor and immune cells and the impact of sGD2 on DB and NAXI-mediated ADCC. Results: DB and NAXI mediated a concentration-dependent ADCC response against GD2-positive spheroids and no response against GD2-negative spheroids. DB showed a significantly higher ADCC potency than NAXI in all GD2-positive spheroid models. Binding activity of DB and NAXI was not significantly different. However, the decrease of anti-GD2 antibody binding to viable GD2-positive tumor cells following co-incubation with dead GD2-positive tumor cells or sGD2 was significantly higher for NAXI than DB. Additionally, we found an increased internalization of NAXI compared to DB by tumor cells and particularly CD64+ monocytes. Finally, sGD2 impaired NAXI-mediated ADCC to a significantly greater extent than DB-mediated ADCC. Conclusions: DB has a higher ADCC potency over NAXI at clinically relevant concentrations, attributed to stronger TMDD effects of NAXI compared to DB.
背景/目的：高危神经母细胞瘤患者接受已获批准的、具有中等结合亲和力（地努图希单抗β；DB）和较高结合亲和力（纳昔妥单抗；NAXI）的抗神经节苷脂GD2抗体治疗。本研究评估了DB与NAXI相比的功能效力，并探讨了其靶点介导的药物处置（TMDD）特性。方法：利用不同GD2表达水平的神经母细胞瘤细胞构建肿瘤球体模型，这些细胞稳定表达iRFP680作为活性标记物。通过长期活细胞活性检测，使用梯度稀释的GD2抗体评估抗体依赖性细胞介导的细胞毒性（ADCC）和补体依赖性细胞毒性（CDC）。结合活性通过流式细胞术测定。分析了TMDD相关过程，包括抗体与死亡肿瘤细胞及可溶性GD2（sGD2）的结合、抗体在肿瘤细胞和免疫细胞中的内化，以及sGD2对DB和NAXI介导的ADCC的影响。结果：DB和NAXI对GD2阳性球体均产生浓度依赖性的ADCC反应，而对GD2阴性球体无反应。在所有GD2阳性球体模型中，DB显示出显著高于NAXI的ADCC效力。DB与NAXI的结合活性无显著差异。然而，与死亡GD2阳性肿瘤细胞或sGD2共孵育后，NAXI在活GD2阳性肿瘤细胞上的抗体结合下降程度显著高于DB。此外，与DB相比，NAXI在肿瘤细胞（尤其是CD64+单核细胞）中的内化程度更高。最后，sGD2对NAXI介导的ADCC的抑制作用显著强于对DB介导的ADCC。结论：在临床相关浓度下，DB较NAXI具有更高的ADCC效力，这归因于NAXI比DB产生更强的TMDD效应。
Affinity Affects the Functional Potency of Anti-GD2 Antibodies by Target-Mediated Drug Disposition
肿瘤(癌症)患者之家