Griffioen Marieke, Kessler Jan H, Borghi Martina, van Soest Ronald A, van der Minne Caroline E, Nouta Jan, van der Burg Sjoerd H, Medema Jan Paul, Schrier Peter I, Falkenburg J H Frederik, Osanto Susanne, Melief Cornelis J M
Department of Clinical Oncology, Leiden University Medical Center, Leiden, Netherlands.
Clin Cancer Res. 2006 May 15;12(10):3130-6. doi: 10.1158/1078-0432.CCR-05-2578.
Preferentially expressed antigen on melanomas (PRAME) is an interesting antigen for T-cell therapy because it is frequently expressed in melanomas (95%) and other tumor types. Moreover, due to its role in oncogenic transformation, PRAME-negative tumor cells are not expected to easily arise and escape from T-cell immunity. The purpose of this study is to investigate the usefulness of PRAME as target for anticancer T-cell therapies.
HLA-A0201-subtyped healthy individuals and advanced melanoma patients were screened for CD8+ T cells directed against previously identified HLA-A0201-binding PRAME peptides by IFN-gamma enzyme-linked immunosorbent spot assays and tetramer staining. PRAME-specific T-cell clones were isolated and tested for recognition of melanoma and acute lymphoid leukemia (ALL) cell lines. PRAME mRNA expression was determined by quantitative real-time reverse transcription-PCR.
In 30% to 40% of healthy individuals and patients, PRA(100-108)-specific CD8+ T cells were detected both after in vitro stimulation and directly ex vivo after isolation by magnetic microbeads. Although CD45RA- memory PRA(100-108)-specific T cells were found in some individuals, the majority of PRA(100-108)-tetramer+ T cells expressed CD45RA, suggesting a naive phenotype. PRA(100-108)-tetramer+ T-cell clones were shown to recognize and lyse HLA-A*0201+ and PRAME+ melanoma but not ALL cell lines. Quantitative real-time reverse transcription-PCR showed significantly lower PRAME mRNA levels in ALL than in melanoma cell lines, suggesting that PRAME expression in ALL is below the recognition threshold of our PRA(100-108)-tetramer+ T cells.
These data support the usefulness of PRAME and in particular the PRA(100-108) epitope as target for T-cell therapy of PRAME-overexpressing cancers.
黑色素瘤优先表达抗原（PRAME）是T细胞治疗中一个有趣的抗原，因为它在黑色素瘤（95%）和其他肿瘤类型中经常表达。此外，由于其在致癌转化中的作用，预计PRAME阴性肿瘤细胞不容易出现并逃避T细胞免疫。本研究的目的是探讨PRAME作为抗癌T细胞治疗靶点的实用性。
通过γ干扰素酶联免疫斑点试验和四聚体染色，对HLA-A0201亚型的健康个体和晚期黑色素瘤患者进行筛查，以寻找针对先前鉴定的与HLA-A0201结合的PRAME肽的CD8+T细胞。分离PRAME特异性T细胞克隆，并检测其对黑色素瘤和急性淋巴细胞白血病（ALL）细胞系的识别能力。通过定量实时逆转录PCR测定PRAME mRNA表达。
在30%至40%的健康个体和患者中，体外刺激后以及通过磁珠分离后直接在体外检测到PRA(100-108)特异性CD8+T细胞。虽然在一些个体中发现了CD45RA-记忆性PRA(100-108)特异性T细胞，但大多数PRA(100-108)四聚体+T细胞表达CD45RA，提示为幼稚表型。PRA(100-108)四聚体+T细胞克隆显示可识别并裂解HLA-A*0201+和PRAME+黑色素瘤细胞系，但不能识别ALL细胞系。定量实时逆转录PCR显示ALL中PRAME mRNA水平显著低于黑色素瘤细胞系，提示ALL中PRAME表达低于我们的PRA(100-108)四聚体+T细胞的识别阈值。
这些数据支持PRAME，特别是PRA(100-108)表位作为PRAME过表达癌症T细胞治疗靶点的实用性。
