Établissement Français du Sang Île-de-France, Paris, France.
Toho University Medical Center Omori Hospital, Tokyo, Japan.
Transfusion. 2022 Nov;62(11):2334-2348. doi: 10.1111/trf.17137. Epub 2022 Oct 14.
There are two FDA-approved anti-CD38 monoclonal antibodies for treatment of multiple myeloma: isatuximab and daratumumab. Owing to expression of CD38 on reagent red blood cells (RBCs), these antibodies interfere with indirect antiglobulin tests (IATs). We sought to understand differences in such interference by performing binding experiments.
In vitro experiments to compare the binding to RBCs of isatuximab and daratumumab alone or in the presence of a mouse anti-human CD38 antibody (HB-7 or AT13/5) or a nicotinamide adenine dinucleotide-analog CD38 inhibitor were performed and quantified by flow cytometry, imaging, mass spectrometry, surface plasmon resonance, and LigandTracer technologies. Serologic testing was performed on plasma samples spiked with isatuximab or daratumumab.
CD38 expressed on RBCs can be directly bound by daratumumab, whereas isatuximab requires a co-factor, such as HB-7, AT13/5, or a CD38 inhibitor, suggesting that the isatuximab epitope on RBCs is masked in vitro. Daratumumab samples more frequently showed interference and had stronger reactions than isatuximab samples. Dithiothreitol treatment was equally effective in mitigating the interference caused by either drug.
Both isatuximab and daratumumab interfere with IATs but at different magnitudes, reflecting distinct binding to CD38 on RBCs. From the binding studies, we conclude that the isatuximab epitope on RBCs is masked in vitro and binding requires a certain CD38 conformation or co-factor. This circumstance may explain why interference is seen only in a subset of patients receiving isatuximab when compared with interference seen in most patients on daratumumab therapy.
有两种经美国食品药品监督管理局批准用于治疗多发性骨髓瘤的抗 CD38 单克隆抗体：依沙妥昔单抗和达雷妥尤单抗。由于 CD38 在试剂红细胞（RBC）上的表达，这些抗体干扰间接抗球蛋白试验（IAT）。我们通过进行结合实验来了解这种干扰的差异。
进行了体外实验，以比较依沙妥昔单抗和达雷妥尤单抗单独或在存在抗人 CD38 单克隆抗体（HB-7 或 AT13/5）或烟酰胺腺嘌呤二核苷酸类似物 CD38 抑制剂的情况下与 RBC 结合的情况，并通过流式细胞术、成像、质谱、表面等离子体共振和 LigandTracer 技术进行定量。对添加了依沙妥昔单抗或达雷妥尤单抗的血浆样本进行血清学检测。
RBC 上表达的 CD38 可直接被达雷妥尤单抗结合，而依沙妥昔单抗需要一个辅助因子，如 HB-7、AT13/5 或 CD38 抑制剂，这表明 RBC 上的依沙妥昔单抗表位在体外被掩盖。达雷妥尤单抗样本比依沙妥昔单抗样本更频繁地显示出干扰，并且反应更强。二硫苏糖醇处理在减轻两种药物引起的干扰方面同样有效。
依沙妥昔单抗和达雷妥尤单抗均干扰 IAT，但程度不同，反映了它们与 RBC 上的 CD38 不同的结合方式。从结合研究中，我们得出结论，RBC 上的依沙妥昔单抗表位在体外被掩盖，并且结合需要特定的 CD38 构象或辅助因子。这种情况可能解释了为什么与达雷妥尤单抗治疗中大多数患者的干扰相比，只有一部分接受依沙妥昔单抗治疗的患者才会出现干扰。
