Antibody-based near-infrared photoimmunotherapy (NIR-PIT) is an attractive strategy for cancer treatment. Tumor cells can be selectively and efficiently killed by the targeted delivery of an antibody–photoabsorber complex followed by exposure to NIR light. Glycoprotein A33 antigen (GPA33) is highly expressed in most human colorectal cancers (CRCs) and is an ideal diagnostic and therapeutic target. We previously produced a single-chain fragment of a variable antibody against GPA33 (A33scFv antibody). Here, we investigate the efficacy of NIR-PIT by combining A33scFv with the NIR photoabsorber IR700 (A33scFv-IR700). In vitro, recombinant A33scFv displayed specific binding and delivery of an NIR dye to GPA33-positive tumor cells. Furthermore, A33scFv-IR700-mediated NIR-PIT was successful in rapidly and specifically killing GPA33-positive colorectal tumor cells. NIR-PIT treatment induced the release of lactate dehydrogenase from tumor cells, followed by cell necrosis, rather than apoptosis, through the promotion of reactive oxygen species accumulation in tumor cells. In mice bearing LS174T tumor grafts, A33scFv selectively accumulated in GPA33-positive tumors. Following only a single injection of the conjugate and subsequent illumination, A33scFv-IR700-mediated NIR-PIT induced a significant increase in therapeutic response in LS174T-tumor mice compared with that in the non-NIR-PIT groups (p < 0.001). Because the GPA33 antigen is specifically expressed in CRC tumors, A33scFv-IR700 might be a promising antibody fragment-photoabsorber conjugate for NIR-PIT of CRC.

中文翻译：

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通过近红外光免疫疗法与GPA33靶向的单链抗体可变片段缀合物对结直肠肿瘤的选择性光杀伤。

基于抗体的近红外光免疫疗法（NIR-PIT）是一种有吸引力的癌症治疗策略。通过靶向递送抗体-光吸收剂复合物然后暴露于NIR光，可以选择性和有效地杀死肿瘤细胞。糖蛋白A33抗原（GPA33）在大多数人类大肠癌（CRC）中高表达，是理想的诊断和治疗靶标。我们先前生产了针对GPA33的可变抗体（A33scFv抗体）的单链片段。在这里，我们通过结合A33scFv和近红外光吸收剂IR700（A33scFv-IR700）来研究NIR-PIT的功效。体外重组A33scFv显示出NIR染料与GPA33阳性肿瘤细胞的特异性结合和传递。此外，A33scFv-IR700介导的NIR-PIT成功地快速特异性杀伤了GPA33阳性结直肠肿瘤细胞。NIR-PIT处理通过促进肿瘤细胞中活性氧的积累，诱导了肿瘤细胞中乳酸脱氢酶的释放，继而引起细胞坏死而不是细胞凋亡。在携带LS174T肿瘤移植物的小鼠中，A33scFv选择性地积聚在GPA33阳性肿瘤中。与非NIR-PIT组相比，仅一次注射结合物并随后照射后，A33scFv-IR700介导的NIR-PIT诱导LS174T肿瘤小鼠的治疗反应显着增加（p<0.001）。因为GPA33抗原在CRC肿瘤中特异性表达，所以A33scFv-IR700可能是CRC的NIR-PIT的有希望的抗体片段-光吸收剂偶联物。