Despite progress in adoptive T-cell therapies, the identification of targets remains a challenge. Although chimeric antigen receptors recognize cell-surface antigens, T-cell receptors (TCR) have the advantage that they can target the array of intracellular proteins by binding to peptides associated with major histocompatibility complex (MHC) products (pepMHC). Although hundreds of cancer-associated peptides have been reported, it remains difficult to identify effective TCRs against each pepMHC complex. Conventional approaches require isolation of antigen-specific CD8+ T cells, followed by TCRαβ gene isolation and validation. To bypass this process, we used directed evolution to engineer TCRs with desired peptide specificity. Here, we compared the activity and cross-reactivity of two affinity-matured TCRs (T1 and RD1) with distinct origins. T1-TCR was isolated from a melanoma-reactive T-cell line specific for MART-1/HLA-A2, whereas RD1-TCR was derived de novo against MART-1/HLA-A2 by in vitro engineering. Despite their distinct origins, both TCRs exhibited similar peptide fine specificities, focused on the center of the MART-1 peptide. In CD4+ T cells, both TCRs mediated activity against MART-1 presented by HLA-A2. However, in CD8+ T cells, T1, but not RD1, demonstrated cross-reactivity with endogenous peptide/HLA-A2 complexes. Based on the fine specificity of these and other MART-1 binding TCRs, we conducted bioinformatics scans to identify structurally similar self-peptides in the human proteome. We showed that the T1-TCR cross-reacted with many of these self-peptides, whereas the RD1-TCR was rarely cross-reactive. Thus, TCRs such as RD1, generated de novo against cancer antigens, can serve as an alternative to TCRs generated from T-cell clones.

中文翻译：

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从头设计的肽特异性T细胞受体可以介导最佳T细胞活性，而不会发生自身交叉反应。

尽管过继性T细胞疗法取得了进展，但是靶标的识别仍然是一个挑战。尽管嵌合抗原受体识别细胞表面抗原，但T细胞受体（TCR）的优势是它们可以通过与主要组织相容性复合物（MHC）产物（pepMHC）相关的肽结合而靶向细胞内蛋白质阵列。尽管已经报道了数百种与癌症相关的肽，但是仍然难以鉴定针对每种pepMHC复合物的有效TCR。常规方法需要分离抗原特异性CD8 + T细胞，然后分离和验证TCRαβ基因。为了绕过该过程，我们使用定向进化来工程改造具有所需肽特异性的TCR。在这里，我们比较了具有不同起源的两个亲和力成熟的TCR（T1和RD1）的活性和交叉反应性。从特异于MART-1 / HLA-A2的黑色素瘤反应性T细胞系中分离出T1-TCR，而RD1-TCR是通过体外工程从头针对MART-1 / HLA-A2衍生的。尽管它们的起源不同，但两种TCR都表现出相似的肽精细特异性，主要集中在MART-1肽的中心。在CD4 + T细胞中，两个TCR都介导了针对HLA-A2呈现的抗MART-1的活性。然而，在CD8 + T细胞中，T1（而非RD1）表现出与内源性肽/ HLA-A2复合物的交叉反应性。基于这些和其他MART-1结合TCR的优良特异性，我们进行了生物信息学扫描，以鉴定人类蛋白质组中结构相似的自身肽。我们表明，T1-TCR与许多这些自肽交叉反应，而RD1-TCR很少与交叉反应。因此，TCR（例如RD1）从头产生了抗癌抗原，