Knoll K, Wrasidlo W, Scherberich J E, Gaedicke G, Fischer P
Laboratory of Molecular Biology, Charité Children's Hospital, Humboldt-University, Berlin, Germany.
Cancer Res. 2000 Nov 1;60(21):6089-94.
In search for a new therapeutic approach for metastasized renal cell carcinoma (RCC), we evaluated the cytotoxicity of a novel prodrug chemoimmunoconjugate with monoclonal antibody (mAb) 138H11 and the DNA-cleaving enediyne calicheamicin thetaI1 (Camtheta) in vitro and in vivo. Previously, mAb 138H11, produced against human renal gamma-glutamyltransferase, stained over 99% clear cell and papillary RCC on frozen sections, showing a membranous expression of the target antigen. In contrast, in normal kidneys gammaGT was restricted to the brush-border in the lumen of proximal tubules and not accessible to the circulation. Thus, human tumor-bearing kidneys perfused in an extra-corporeal system with 99mTc-138H11 revealed a high, specific uptake into the tumor. In this study, fluorescence-activated cell sorting analysis showed binding of mAb 138H11 to RCC cell lines, whereas squamous cell carcinoma lines, fibroblasts, and the murine RENCA were negative. XTT cell proliferation assays revealed efficient killing of the Caki-1 cell line by the 138H11-Camtheta conjugate using SPDP (EC50 = 5 x 10(-11) M) as a covalent linker. For in vivo testing, five groups of eight nude mice each were injected with 2.5 x 10(6) Caki-1 cells s.c. and treated with the following: (a) PBS; (b) 138H11; (c) Camtheta; (d) a mixture of 138H11 and Camtheta; and (e) 138H11-Camtheta conjugate. Treatment started on day 1 after tumor induction and was repeated three times. The data show a highly significant inhibition of tumor growth with the 138H11-Camtheta conjugate versus PBS (P = 0.004). Only mice treated with 138H11-Camtheta showed a tumor shrinkage to minimal residues. In a second experiment, lower doses of the 138H11-Camtheta conjugate were compared with an antineuroblastoma mAb (ch14.18), confirming targeted killing of RCC by the 138H11-Camtheta conjugate at tolerable toxicity in vivo. In conclusion, these combined results encourage further studies for targeted therapy of metastatic RCC with mAb 138H11 conjugates.
为寻找转移性肾细胞癌（RCC）的新治疗方法，我们在体外和体内评估了一种新型前药化学免疫偶联物（其由单克隆抗体（mAb）138H11与可切割DNA的烯二炔加利车霉素θI1（Camθ）组成）的细胞毒性。此前，针对人肾γ-谷氨酰转移酶产生的mAb 138H11，在冰冻切片上可使超过99%的透明细胞型和乳头状RCC染色，显示出靶抗原的膜性表达。相比之下，在正常肾脏中，γGT局限于近端小管管腔内的刷状缘，无法进入循环系统。因此，在体外系统中用99mTc-138H11灌注荷人肿瘤的肾脏时，肿瘤显示出高特异性摄取。在本研究中，荧光激活细胞分选分析显示mAb 138H11与RCC细胞系结合，而鳞状细胞癌系、成纤维细胞和小鼠RENCA细胞系呈阴性。XTT细胞增殖试验显示，使用SPDP（EC50 = 5×10⁻¹¹ M）作为共价连接体时，138H11-Camθ偶联物可有效杀伤Caki-1细胞系。为进行体内试验，将五组每组八只裸鼠皮下注射2.5×10⁶个Caki-1细胞，并给予以下处理：（a）磷酸盐缓冲液（PBS）；（b）138H11；（c）Camθ；（d）138H11和Camθ的混合物；（e）138H11-Camθ偶联物。在肿瘤接种后第1天开始治疗，并重复三次。数据显示，与PBS相比，138H-11Camθ偶联物对肿瘤生长有高度显著的抑制作用（P = 0.004）。只有用138H11-Camθ治疗的小鼠肿瘤缩小至最小残留。在第二个实验中，将较低剂量的138H11-Camθ偶联物与一种抗神经母细胞瘤mAb（ch14.18）进行比较，证实138H11-Camθ偶联物在体内可耐受毒性的情况下对RCC有靶向杀伤作用。总之这些综合结果鼓励进一步研究用mAb 138H11偶联物对转移性RCC进行靶向治疗。
