Anti-CD38 VHH antibody (JK36) reliably detects CD38 yet uncovers CD38 downregulation in a subset of daratumumab-treated multiple myeloma patients.

IF 2.7 3区 医学 Q3 MEDICAL LABORATORY TECHNOLOGY
Veronika Ecker, Martha-Lena Müller, Jana Wobst, Wolfgang Kern
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Abstract

CD38 and CD138 are important diagnostic markers in flow cytometric analysis of plasma cells (PC) in the context of multiple myeloma (MM). Anti-CD38 therapy, such as daratumumab, exacerbates CD38 detection. In addition, CD138 can be degraded and is then no longer easily detectable on the cell surface. Variable heavy domain heavy chain antibodies (VHH) are single variable domain antibody fragments. Clone JK36 consists of two anti-CD38 VHH fragments and allows targeting of a cryptic CD38 epitope that is not accessible to conventional antibodies (CA). Therefore, our aim was to test VHH in comparison to our conventional anti-CD38 antibody (LS198) in MM bone marrow samples after daratumumab therapy (d-t) compared to therapy-naïve (n) and samples with unknown therapy. A total of 111 samples were analyzed (n = 11 n, n = 81 d-t, n = 18 with unknown therapy). While CD38 was equally well detected by VHH and CA in therapy-naïve samples, CD38 could only be detected in 8% of d-t samples with CA but in 91% with VHH. This resulted in an overall significant reduction in the number of detectable PC, and three samples with undetectable PC by CA compared to VHH. Furthermore, CD138 was reduced/degraded in 52% of d-t samples of which 88% had undetectable CD38 by CA. In addition to proper detection of CD38, VHH is also able to determine a potential CD38 reduction of cell surface expression, as shown by a reduction in CD38 median fluorescence intensity (MFI) on d-t compared to n samples. One d-t sample revealed two distinct PC populations differing by dim and bright CD38 expression, only detectable by VHH. Interestingly, samples with unknown treatment history can be grouped into scenarios most likely treated with daratumumab, or rather treatment-naïve, respectively. In summary, VHH provides superior CD38 detection in d-t MM patients, which is vital for diagnostic samples, and it is capable of providing information about CD38 integrity on the cell surface.

抗CD38 VHH抗体(JK36)可靠地检测CD38,并发现在daratumumab治疗的多发性骨髓瘤患者亚群中CD38下调。
CD38和CD138是多发性骨髓瘤(MM)血浆细胞(PC)流式细胞术分析中重要的诊断标志物。抗CD38治疗,如达拉单抗,加重CD38检测。此外,CD138可以被降解,然后在细胞表面不再容易检测到。可变重域重链抗体(VHH)是一种单可变域抗体片段。克隆JK36由两个抗CD38 VHH片段组成,并允许靶向传统抗体(CA)无法接近的隐性CD38表位。因此,我们的目的是测试VHH与我们传统的抗cd38抗体(LS198)在经达拉单抗治疗(d-t)、therapy-naïve (n)和未知治疗的MM骨髓样本中的比较。共分析了111例样本(n = 11n, n = 81 d-t, n = 18治疗方法未知)。虽然在therapy-naïve样品中,VHH和CA同样能很好地检测到CD38,但在CA样品中,CD38只能在8%的d-t样品中检测到,而在VHH样品中,CD38的检测率为91%。与VHH相比,这导致了可检测PC数量的总体显着减少,并且CA有三个样品无法检测到PC。此外,CD138在52%的d-t样品中被还原/降解,其中88%的样品无法被CA检测到。除了CD38的适当检测外,VHH还能够确定CD38在细胞表面表达的潜在降低,这表明与n样品相比,d-t上CD38中位荧光强度(MFI)降低。一个d-t样本显示了两个不同的PC群体,不同的CD38表达暗淡和明亮,只能通过VHH检测到。有趣的是,具有未知治疗史的样本可以分别分为最有可能使用daratumumab治疗的情况,或者更确切地说treatment-naïve。综上所述,VHH在d-t MM患者中提供了优越的CD38检测,这对诊断样本至关重要,它能够提供关于细胞表面CD38完整性的信息。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
6.80
自引率
32.40%
发文量
51
审稿时长
>12 weeks
期刊介绍: Cytometry Part B: Clinical Cytometry features original research reports, in-depth reviews and special issues that directly relate to and palpably impact clinical flow, mass and image-based cytometry. These may include clinical and translational investigations important in the diagnostic, prognostic and therapeutic management of patients. Thus, we welcome research papers from various disciplines related [but not limited to] hematopathologists, hematologists, immunologists and cell biologists with clinically relevant and innovative studies investigating individual-cell analytics and/or separations. In addition to the types of papers indicated above, we also welcome Letters to the Editor, describing case reports or important medical or technical topics relevant to our readership without the length and depth of a full original report.
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