In vivo target-specific activatable near-infrared optical labeling of humanized monoclonal antibodies.
In vivo target-specific activatable near-infrared optical labeling of humanized monoclonal antibodies.
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DOI：
10.1158/1535-7163.mct-08-0862
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发表时间：
2009-01
影响因子：
5.7
通讯作者：
Kobayashi H
中科院分区：
文献类型：
--
作者：
Ogawa M;Regino CA;Choyke PL;Kobayashi H
用标记的单克隆抗体成像可能有助于肿瘤的检测、分期和监测。尽管它们具有高亲和力和特异性，但抗体成像的一个关键限制是由于从血液中清除的时间延长而导致的高背景信号，这降低了肿瘤与背景比（TBR）。为了解决这个问题，我们开发了一种分子成像探针，该探针由多个自猝灭荧光团（Cy 5. 5或Alexa 680）与单克隆抗体（曲妥珠单抗-Tra）缀合组成，以分别合成Tra-Cy 5.5（SQ）或Tra-Alexa 680（SQ）。该试剂仅在细胞内化后变得具有荧光“活性”，但在未结合状态下被淬灭，导致高TBR。两种缀合物的体外猝灭能力约为9倍。在携带3 T3/HER 2+和Balb/3 T3/ZsGreen/HER 2-异种移植物的小鼠中进行体内成像实验。Tra-Alexa 680（SQ）在3 T3/HER 2+肿瘤中产生特异性增强，但在HER 2对照肿瘤中不产生特异性增强。然而，Tra-Cy 5.5（SQ）在3 T3/HER 2+和对照肿瘤中均产生非特异性增强。总之，虽然Cy5.5产生非特异性结果以及快速肝脏蓄积，但将多个Alexa 680分子缀合至单个单克隆抗体产生近红外（NIR）光学剂，其在具有高TBR的特定靶肿瘤内活化，具有相当大的临床转化潜力。
Imaging with labeled monoclonal antibodies may be useful in detecting, staging and monitoring tumors. Despite their high affinity and specificity, a critical limitation of antibody imaging is the high background signal due to prolonged clearance from the blood which reduces the tumor-to-background ratio (TBR). To address this problem, we developed an molecular imaging probe consisting of multiple self-quenching, fluorophores (Cy5.5 or Alexa680) conjugated to a monoclonal antibody (trastuzumab-Tra) to synthesize Tra-Cy5.5(SQ) or Tra-Alexa680(SQ) respectively. This agent only becomes fluorescently “active” after cellular internalization but is quenched in the unbound state leading to high TBRs. The in vitro quenching capacity for both conjugates was approximately 9-fold. In vivo imaging experiments were performed in mice bearing both 3T3/HER2+ and Balb/3T3/ZsGreen/HER2- xenografts. Tra-Alexa680(SQ) produced specific enhancement in the 3T3/HER2+ tumors but not in the HER2- control tumors. However, Tra-Cy5.5(SQ) produced non-specific enhancement in both 3T3/HER2+ and control tumors. In conclusion, while Cy5.5 produced non-specific results as well as rapid liver accumulation, conjugating multiple Alexa680 molecules to a single monoclonal antibody resulted in a near-infrared (NIR) optical agent that activated within specific target tumors with high TBR with considerable potential for clinical translation.