Wang Xinhui, Ko Eric C, Peng Liaomin, Gillies Stephen D, Ferrone Soldano
Department of Immunology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
Cancer Res. 2005 Aug 1;65(15):6976-83. doi: 10.1158/0008-5472.CAN-04-2328.
To overcome unresponsiveness to the self-high molecular weight melanoma-associated antigen (HMW-MAA) in hosts with constitutive HMW-MAA expression, we have used as immunogen the anti-idiotypic monoclonal antibody (mAb) MK2-23, which mimics the antigenic determinant recognized by the anti-HMW-MAA mAb 763.74. In a phase I/II clinical trial, anti-idiotypic mAb MK2-23, conjugated to keyhole limpet hemocyanin (KLH) as a carrier and given with Bacillus Calmette-Guerin (BCG) as an adjuvant, elicited HMW-MAA-specific antibodies in about 60% of the immunized melanoma patients. The immune response was associated with survival prolongation. However, safety and standardization issues associated with the use of KLH and BCG in the clinical setting have prompted us to develop alternative immunization strategies. Conjugation of human interleukin 2 (IL-2) to mAb MK2-23 variable regions covalently linked to human immunoglobulin constant regions enhanced mAb MK2-23 immunogenicity in BALB/c mice to an extent similar to that induced by mAb MK2-23 conjugated to KLH and given with Freund's adjuvant. As determined by the level of serum antibodies and delayed-type hypersensitivity responses to HMW-MAA-bearing melanoma cells, immunization of mice with the MK2-23-IL-2 fusion protein elicited more robust humoral and cellular responses, respectively, than immunization with KLH-conjugated mAb MK2-23 and separate administration of IL-2. The immunogenicity of the fusion protein is dependent on IL-2 conjugation, because immunization of mice with either mAb MK2-23 or chimeric mAb MK2-23, in combination with IL-2, was not as effective in eliciting HMW-MAA-specific immune responses. These results suggest that the MK2-23-IL-2 fusion protein represents a useful immunogen to implement active specific immunotherapy in patients with melanoma, because it bypasses the requirement for KLH conjugation and adjuvant administration.
为克服在组成性表达高分子量黑色素瘤相关抗原（HMW-MAA）的宿主中对自身HMW-MAA的无反应性，我们使用抗独特型单克隆抗体（mAb）MK2-23作为免疫原，该抗体模拟抗HMW-MAA单克隆抗体763.74识别的抗原决定簇。在一项I/II期临床试验中，与钥孔戚血蓝蛋白（KLH）偶联作为载体并与卡介苗（BCG）作为佐剂一起给予的抗独特型单克隆抗体MK2-23，在约60%的免疫黑色素瘤患者中引发了HMW-MAA特异性抗体。免疫反应与生存期延长相关。然而，在临床环境中使用KLH和BCG相关的安全性和标准化问题促使我们开发替代免疫策略。将人白细胞介素2（IL-2）与共价连接至人免疫球蛋白恒定区的mAb MK2-23可变区偶联，在BALB/c小鼠中增强了mAb MK2-23的免疫原性，其程度与用与弗氏佐剂一起给予的与KLH偶联的mAb MK2-23诱导的程度相似。根据血清抗体水平和对携带HMW-MAA的黑色素瘤细胞的迟发型超敏反应确定，用MK2-23-IL-2融合蛋白免疫小鼠分别比用与KLH偶联的mAb MK2-23和单独给予IL-2免疫引发更强的体液和细胞反应。融合蛋白的免疫原性取决于IL-2偶联，因为用mAb MK2-23或嵌合mAb MK2-23与IL-2联合免疫小鼠在引发HMW-MAA特异性免疫反应方面效果不佳。这些结果表明，MK2-23-IL-2融合蛋白是一种有用的免疫原，可用于对黑色素瘤患者实施主动特异性免疫治疗，因为它绕过了对KLH偶联和佐剂给药的需求。
