Vakili Hana, Koorse Germans Sharon, Dong Xiuhua, Kansagra Ankit, Patel Hetalkumari, Muthukumar Alagarraju, Hashim Ibrahim A
Department of Pathology, Clinical Chemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Department of Internal Medicine, Hematology/Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Diagnostics (Basel). 2020 Apr 14;10(4):219. doi: 10.3390/diagnostics10040219.
Therapeutic humanized IgG1 kappa monoclonal antibody (t-mAb), daratumumab (DARA) is a Food and Drug Administration approved drug for the treatment of relapsed/refractory plasma cell myeloma (PCM). DARA appears on serum protein electrophoresis (SPEP) and on serum immunofixation (sIFE) as an IgG kappa monoclonal immunoglobulin protein (M-protein), complicating the assessment of the patients' response to therapy. A more ominous threat to patient safety can occur with the misinterpretation of the presence of a small t-mAb spike as being the residual product of the patient's neoplastic clone, presented either as oligoclonality or new clonality, which could result in incorrect interpretation of failure to achieve remission.
In this report, we describe a novel and cost-effective technique based on biotinylated recombinant CD38 and streptavidin-coated magnetic beads to capture and remove residual DARA present in PCM patient serum samples. The treated samples are then run like regular samples on SPEP and sIFE. We validated this simple technique in DARA-spiked PCM samples and patient samples on DARA treatment.
Our simple capture technique completely extracted DARA in all of the tested serum specimens and allowed the assessment of residual M-protein without DARA interference. The results were reproducible and highly specific for DARA, and did not have any impact on endogenous M-protein migration and quantification by SPEP and sIFE. The cost of this technique is much lower and it can be performed in-house with a very short turnaround time compared to the currently available alternative methods. There is a great need for such reflex technologies to avoid interpretation errors.
This method is an effective way to eliminate DARA interference in SPEP and sIFE, and can be easily implemented in any clinical laboratory without any patent restriction. This simple technique can be adopted for other t-mAbs using their respective ligands and will help to reduce additional doses of toxic treatment and further testing in patients on t-mAbs with a false positive M-protein spike.
治疗性人源化IgG1κ单克隆抗体（t - 单克隆抗体）达雷妥尤单抗（DARA）是一种经美国食品药品监督管理局批准用于治疗复发/难治性浆细胞骨髓瘤（PCM）的药物。DARA在血清蛋白电泳（SPEP）和血清免疫固定电泳（sIFE）上表现为IgGκ单克隆免疫球蛋白蛋白（M蛋白），这使得评估患者对治疗的反应变得复杂。更严重的是，若将小的t - 单克隆抗体峰误判为患者肿瘤克隆的残留产物，表现为寡克隆性或新的克隆性，可能会导致对未达到缓解的错误解读，从而对患者安全构成更大威胁。
在本报告中，我们描述了一种基于生物素化重组CD38和链霉亲和素包被磁珠的新颖且经济高效的技术，用于捕获和去除PCM患者血清样本中存在的残留DARA。然后将处理后的样本像常规样本一样进行SPEP和sIFE检测。我们在添加了DARA的PCM样本以及接受DARA治疗的患者样本中验证了这种简单技术。
我们的简单捕获技术在所有测试的血清标本中完全提取了DARA，并能够在无DARA干扰的情况下评估残留M蛋白。结果具有可重复性且对DARA具有高度特异性，并且对SPEP和sIFE检测内源性M蛋白的迁移和定量没有任何影响。与目前可用的替代方法相比，该技术成本更低，可在内部进行，周转时间非常短。非常需要这样的反射技术来避免解读错误。
该方法是消除DARA对SPEP和sIFE干扰的有效途径，可在任何临床实验室轻松实施，且无任何专利限制。这种简单技术可用于其他使用各自配体的t - 单克隆抗体，有助于减少对M蛋白峰呈假阳性的t - 单克隆抗体治疗患者的额外毒性治疗剂量和进一步检测。
