Department of Urology, University Hospital Freiburg, Germany.
J Immunother. 2010 Apr;33(3):262-71. doi: 10.1097/CJI.0b013e3181c5495c.
The prostate-specific membrane antigen (PSMA) is abundantly expressed on prostate cancer epithelial cells and its expression correlates with tumor progression. Therefore, a specific immunotherapy against this antigen may be a novel therapeutic option for the management of prostate cancer. We generated an anti-PSMA single-chain antibody fragment (scFv), called D7, by phage display from the monoclonal antibody 3/F11. By C-terminal ligation of the toxic domain of Pseudomonas Exotoxin A (PE40) to the genes of D7, the immunotoxin D7-PE40 was generated. D7 and D7-PE40 specifically bound to PSMA transfectants and to the PSMA expressing prostate cancer cell line C4-2. In addition, D7-PE40 showed a high serum stability and induced a 50% reduction of viability (IC50) in C4-2 cells at a concentration of 140 pM. In vivo, D7-PE40 was well tolerated in SCID mice up to a single dose of 20 microg, whereas higher doses induced severe hepatotoxicity with deaths of the animals. Immunotoxin treatment of mice bearing C4-2 tumor xenografts caused a significant inhibition of tumor growth, whereas mice with PSMA-negative DU 145 tumors remained unaffected. Owing to its high and specific cytotoxicity and its capability to inhibit prostate tumor growth in vivo the immunotoxin D7-PE40 represents a promising candidate for the immunotherapy of prostate cancer.
前列腺特异性膜抗原（PSMA）在前列腺癌细胞上表达丰富，其表达与肿瘤进展相关。因此，针对该抗原的特异性免疫治疗可能是前列腺癌治疗的一种新的治疗选择。我们通过噬菌体展示从单克隆抗体 3/F11 中生成了一种抗 PSMA 的单链抗体片段（scFv），称为 D7。通过将 Pseudomonas Exotoxin A（PE40）的毒性结构域连接到 D7 的 C 末端，生成了免疫毒素 D7-PE40。D7 和 D7-PE40 特异性结合 PSMA 转染细胞和表达 PSMA 的前列腺癌细胞系 C4-2。此外，D7-PE40 具有较高的血清稳定性，在浓度为 140 pM 时可使 C4-2 细胞的活力降低 50%（IC50）。在体内，D7-PE40 在 SCID 小鼠中耐受良好，最高剂量可达 20μg，而更高剂量会导致严重的肝毒性，导致动物死亡。免疫毒素治疗携带 C4-2 肿瘤异种移植物的小鼠可显著抑制肿瘤生长，而 PSMA 阴性 DU 145 肿瘤小鼠则不受影响。由于其高特异性和细胞毒性以及在体内抑制前列腺肿瘤生长的能力，免疫毒素 D7-PE40 是前列腺癌免疫治疗的有前途的候选药物。
