Boross Peter, Jansen J H Marco, van Tetering Geert, Nederend Maaike, Brandsma Arianne, Meyer Saskia, Torfs Ellen, van den Ham Henk-Jan, Meulenbroek Laura, de Haij Simone, Leusen Jeanette H W
Immunotherapy Laboratory, Laboratory for Translational Immunology, University Medical Center Utrecht, The Netherlands.
Immunotherapy Laboratory, Laboratory for Translational Immunology, University Medical Center Utrecht, The Netherlands.
Immunol Lett. 2014 Aug;160(2):151-7. doi: 10.1016/j.imlet.2014.02.005. Epub 2014 Mar 5.
Patients suffering from advanced melanoma have a very poor prognosis. Despite recent advances in the understanding of oncogenic mechanisms and therapeutic interventions, the median survival of patients with metastatic disease is less than 12 months. Immunotherapy of melanoma has been intensely investigated and holds great promises. Tyrosinase-related protein-1 or gp75 (TYRP-1/gp75) antigen is a melanosomal polypeptide. It is the most abundant glycoprotein synthesized by pigmented melanocytes and melanomas. It is specific for melanocytes and both primary and metastatic melanomas. In mice, administration of the mouse mAb anti-gp75 TA99 prevents outgrowth of B16F10 melanoma metastases. The activity of TA99 is dependent on the presence and activity of the IgG specific, Fc receptors. TA99 cross-reacts with human gp75, and is currently being used for diagnosis of patients. Here, we sequenced mIgG2a TA99 and found that the locus harboring the endogenous light chain of the fusion partner in the TA99 hybridoma cells is not inactivated, resulting in the production of a mixed pool of mAbs that mitigates binding to gp75. Since human IgG1 (hIgG1) is the most frequently used mAb format in clinical studies, we produced a recombinant hIgG1 TA99 molecule. Whereas it is known that hIgG1 can functionally interact with mouse Fc receptors, we found that hIgG1 TA99 did not exhibit in vivo activity against B16F10 melanoma in wild type C57BL/6 mice. However, results obtained in this study demonstrated anti-tumor activity of hIgG1 TA99 in FcγRIIB knockout mice and in human FcγRI transgenic mice. These results emphasize the need for testing hIgG mAb in mice with functional human FcγRs.
患有晚期黑色素瘤的患者预后非常差。尽管在致癌机制和治疗干预的理解方面取得了最新进展，但转移性疾病患者的中位生存期仍不到12个月。黑色素瘤的免疫疗法已得到深入研究并具有很大前景。酪氨酸酶相关蛋白-1或gp75（TYRP-1/gp75）抗原是一种黑素小体多肽。它是色素沉着的黑素细胞和黑色素瘤合成的最丰富的糖蛋白。它对黑素细胞以及原发性和转移性黑色素瘤具有特异性。在小鼠中，给予抗gp75 TA99小鼠单克隆抗体可阻止B16F10黑色素瘤转移的生长。TA99的活性取决于IgG特异性Fc受体的存在和活性。TA99与人gp75发生交叉反应，目前正用于患者的诊断。在此，我们对mIgG2a TA99进行了测序，发现TA99杂交瘤细胞中携带融合伴侣内源性轻链的基因座未失活，导致产生了一组混合的单克隆抗体，从而降低了与gp75的结合。由于人IgG1（hIgG1）是临床研究中最常用的单克隆抗体制剂，我们制备了重组hIgG1 TA99分子。虽然已知hIgG1可与小鼠Fc受体发生功能性相互作用，但我们发现hIgG1 TA99在野生型C57BL/6小鼠中对B16F10黑色素瘤没有体内活性。然而，本研究获得的结果表明hIgG1 TA99在FcγRIIB基因敲除小鼠和人FcγRI转基因小鼠中具有抗肿瘤活性。这些结果强调了在具有功能性人FcγRs的小鼠中测试hIgG单克隆抗体的必要性。
