Tumor targeting properties of monoclonal antibodies with different affinity for target antigen CD44V6 in nude mice bearing head-and-neck cancer xenografts
Tumor targeting properties of monoclonal antibodies with different affinity for target antigen CD44V6 in nude mice bearing head-and-neck cancer xenografts
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DOI：
10.1002/ijc.10369
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发表时间：
2002-05-20
影响因子：
6.4
通讯作者：
van Dongen, GAMS
中科院分区：
文献类型：
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作者：
Verel, I;Heider, KH;van Dongen, GAMS
CD44蛋白家族由具有组织特异性表达的异构体组成，由同一基因的标准外显子和多达9个选择性剪接的变异外显子(v2-v10)编码。小鼠单抗U36和Biwa-1针对CD44 V6区域内的重叠表位，先前已被证明有效地靶向HNSCC。在此，我们报道了Biwa-1的I嵌合(Biwa-2)和人源化(Biwa-4和Biwa-8)衍生物的构建。与U36和Biwa-1一起，评估了这些新抗体与抗原的体外亲和力，以及在携带HNSCC异种移植株HNX-OE的裸鼠体内的生物分布和疗效。通过表面等离子体共振测定，与CD44v6结合的单抗的亲和力差异高达46倍(K-d从1.1×10(-8)到2.4×10(-10)M)，顺序如下：mMAb U36<；hMAb Biwa-4<；hMAb Biwa-8<；mMAb Biwa-1类似于CMAB Biwa-2。为了评估它们的体内肿瘤靶向性，将2株具有相同的鼠或人1311 12亚型的单抗标记为或51，并成对同时给药(各50杯/10MUCI)，显示亲和力差异逐步降低：U36与Biwa-I(差异35.0倍)，Biwa-4与Biwa-2(14.0倍)，Biwa-4与Biwa-8(4.0倍)。分别于注射后第1、2、3或4、7天进行生物分布评价。值得注意的是，对于所有测试的3对单抗，低亲和力的单抗显示出更高的肿瘤定位程度和特异性。亲和力差异越大，肿瘤定位的差异越明显。例如，注射3天后，低亲和力mMAb U36的肿瘤摄取率比高亲和力mMAb Biwa-1高50%，而血液水平和器官摄取率相似。经186Re(300或400Muci)标记后，相同的单抗对显示出与生物分布数据一致的RIT效果：Re-186-U36比186Re-Biwa-I更有效，Re-186-Biwa-4略高于Re-186-Biwa-2，Re-186-Biwa-4和Re-186-Biwa-8表现出相似的效果。基于这些数据，我们得出结论，与这些抗体的高亲和力版本相比，与给定的靶抗原(例如，U36、Biwa-4)亲和力明显较低的抗体可能显示出更好的肿瘤靶向性。(C)2002年Wiley-Liss，Inc.
The CD44 protein family consists of isoforms with tissue-specific expression, which are encoded by standard exons and up to 9 alternatively spliced variant exons (v2-v10) of the same gene. The murine MAbs U36 and BIWA-1, directed against overlapping epitopes within the v6 region of CD44, have previously been shown to efficiently target HNSCC. We herein report on the construction of I chimeric (BIWA-2) and 2 humanized (BIWA-4 and BIWA-8) derivatives of BIWA-1. Together with U36 and BIWA-1, these new antibodies were evaluated for affinity to the antigen in vitro as well as for biodistribution and efficacy in RIT using nude mice bearing the HNSCC xenograft line HNX-OE. As determined by surface plasmon resonance, the MAbs bound to CD44v6 with an up to 46-fold difference in affinity (K-d ranging from 1.1 x 10(-8) to 2.4 x 10(-10) M) with the following ranking: mMAb U36 < hMAb BIWA-4 < hMAb BIWA-8 < mMAb BIWA-I similar to cMAb BIWA-2. To evaluate their in vivo tumor-targeting properties, 2 MAbs with identical murine or human 1311 12 isotype were labeled with either or 51 and administered simultaneously (50 mug/10 muCi each) as pairs showing a step-wise decrease in the difference in affinity: U36 vs. BIWA-I (35.0-fold difference), BIWA-4 vs. BIWA-2 (14.0-fold) and BIWA-4 vs. BIWA-8 (4.0-fold). Biodistribution was assessed at 1, 2, 3 or 4 and 7 days after injection. Remarkably, for all 3 MAb pairs tested, the lower-affinity MAb showed a higher degree and specificity of tumor localization. The difference in tumor localization was more pronounced when the difference in affinity was larger. For example, 3 days after injection, the lower-affinity mMAb U36 showed a 50% higher tumor uptake than the higher-affinity mMAb BIWA-1, while blood levels and uptake in organs were similar. After labeling with 186 Re (300 or 400 muCi), the same MAb pairs showed RIT efficacy consistent with the biodistribution data: Re-186-U36 was more effective than 186 Re-BIWA-I, Re-186-BIWA-4 was slightly more effective than Re-186-BIWA-2 and Re-186-BIWA-4 and Re-186-BIWA-8 demonstrated similar efficacy. Based on these data, we conclude that antibodies with markedly lower affinity to a given target antigen (e.g., U36, BIWA-4) may show superior tumor targeting in comparison with higher-affinity versions of these antibodies. (C) 2002 Wiley-Liss, Inc.