Wikstrand C J, McLendon R E, Friedman A H, Bigner D D
Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Cancer Res. 1997 Sep 15;57(18):4130-40.
The potential of therapeutic targeting of tumor cell surface epidermal growth factor receptors (EGFRs) by modified ligands or specific antibodies has been limited by the normal tissue distribution of the receptor. The identification and characterization of a variant of this receptor, EGFRvIII, which is not expressed in normal tissues but has been described in gliomas, non-small cell lung carcinomas, and breast carcinomas, has provided a highly specific, internalizing target for antibody-mediated approaches. To determine the feasibility of immunotargeting EGFRvIII, we have assessed the qualitative distribution and quantitative expression at both the population and cellular levels of EGFRvIII in 21 biopsy samples of human gliomas by indirect analytical and quantitative flow cytometry and by immunohistochemical assay of frozen and formalin-fixed tissue. Consistent with previous reports, 50% of gliomas tested (1 of 2 anaplastic astrocytomas, 7 of 12 glioblastoma multiforme, and 2 of 6 oligodendrogliomas) expressed EGFRvIII, as determined by a minimum of 2 separate assays. Minimum estimates of the proportion of positive tumor cells in these populations ranged from 37-86%; in four of five cases in which quantitation of the EGFRvIII density/cell was performed, values of 2.7-6.8 x 10(5) were obtained with monoclonal antibody (mAb) L8A4 (EGFRvIII specific), levels consistent with successful in vivo immunotargeting. Confocal microscopic analysis confirmed that the subcellular localization of EGFRvIII was identical to that described for EGFR: predominant cell membrane expression, with some perinuclear distribution suggestive of localization to the Golgi region. Neither EGFR nor EGFRvIII was found within the nucleus. This study establishes for the first time that approximately 50% of human glioma biopsies contain cell populations expressing a sufficient number of membrane-expressed EGFRvIIIs to mediate specific anti-EGFRvIII mAb localization. Coupled with previous demonstrations of the rapid internalization of specific mAb-EGFRvIII complexes and the susceptibility of the targeted cells to isotope or toxin-mediated cytotoxicity, this study establishes the validity of targeting EGFRvIII for therapy of mutant receptor-positive gliomas, breast carcinomas, and non-small cell lung carcinomas.
通过修饰配体或特异性抗体对肿瘤细胞表面表皮生长因子受体（EGFRs）进行治疗靶向的潜力，受到该受体在正常组织中的分布限制。一种该受体变体EGFRvIII的鉴定和特征描述，为抗体介导的方法提供了一个高度特异性、可内化的靶点，该变体在正常组织中不表达，但已在神经胶质瘤、非小细胞肺癌和乳腺癌中被发现。为了确定免疫靶向EGFRvIII的可行性，我们通过间接分析和定量流式细胞术以及对冷冻和福尔马林固定组织进行免疫组织化学检测，评估了21例人类神经胶质瘤活检样本中EGFRvIII在群体和细胞水平上的定性分布和定量表达。与之前的报道一致，通过至少两种独立检测确定，50%的检测神经胶质瘤（2例间变性星形细胞瘤中的1例、12例多形性胶质母细胞瘤中的7例以及6例少突胶质细胞瘤中的2例）表达EGFRvIII。这些群体中阳性肿瘤细胞比例的最低估计值在37%至86%之间；在五例对EGFRvIII密度/细胞进行定量的病例中，使用单克隆抗体（mAb）L8A4（EGFRvIII特异性）获得的值为2.7 - 6.8×10⁵，这些水平与体内免疫靶向成功一致。共聚焦显微镜分析证实，EGFRvIII的亚细胞定位与EGFR描述的相同：主要在细胞膜表达，一些核周分布提示定位于高尔基体区域。在细胞核内未发现EGFR和EGFRvIII。这项研究首次证实，约50%的人类神经胶质瘤活检样本含有表达足够数量膜表达EGFRvIIIs以介导特异性抗EGFRvIII单克隆抗体定位的细胞群体。结合之前关于特异性mAb - EGFRvIII复合物快速内化以及靶向细胞对同位素或毒素介导的细胞毒性敏感性的证明，这项研究确立了靶向EGFRvIII治疗突变受体阳性神经胶质瘤、乳腺癌和非小细胞肺癌的有效性。
