Investigational Cancer Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Adult Allergy and Immunology, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
J Immunother Cancer. 2023 Aug;11(8). doi: 10.1136/jitc-2023-007236.
Immune checkpoint inhibitors have revolutionized cancer treatment. However, they are associated with a unique spectrum of side effects, called immune-related adverse events (irAEs), which can cause significant morbidity and quickly progress to severe or life-threatening events if not treated promptly. Identifying predictive biomarkers for irAEs before immunotherapy initiation is therefore a critical area of research. Polymorphisms within the T-cell receptor beta (TCRB) variable (TRBV) gene have been implicated in autoimmune disease and may be mechanistically linked to irAEs. However, the repetitive nature of the TCRB locus and incomplete genome assembly has hampered the evaluation of TRBV polymorphisms in the past.
We used a novel method for long-amplicon next generation sequencing of rearranged TCRB chains from peripheral blood total RNA to evaluate the link between TRBV polymorphisms and irAEs in patients treated with immunotherapy for cancer. We employed multiplex PCR to create amplicons spanning the three beta chain complementarity-determining regions (CDR) regions to enable detection of polymorphism within the germline-encoded framework and CDR1 and CDR2 regions in addition to CDR3 profiling. Resultant amplicons were sequenced via the Ion Torrent and TRBV allele profiles constructed for each individual was correlated with irAE annotations to identify haplotypes associated with severe irAEs (≥ grade 3).
Our study included 81 patients who had irAEs when treated with immunotherapy for cancer. By using principal component analysis of the 81 TRBV allele profiles followed by k-means clustering, we identified six major TRBV haplotypes. Strikingly, we found that one-third of this cohort possessed a TRBV allele haplotype that appeared to be protective against severe irAEs.
The data suggest that long-amplicon TCRB repertoire sequencing can potentially identify TRBV haplotype groups that correlate with the risk of severe irAEs. Germline-encoded TRBV polymorphisms may serve as a predictive biomarker of severe irAEs.
免疫检查点抑制剂彻底改变了癌症治疗。然而，它们与一种独特的副作用谱有关，称为免疫相关不良事件（irAEs），如果不及时治疗，这些副作用可能导致严重或危及生命的事件。因此，在免疫治疗开始之前识别 irAEs 的预测生物标志物是一个关键的研究领域。T 细胞受体 β（TCRB）可变区（TRBV）基因内的多态性与自身免疫性疾病有关，并且可能在机制上与 irAEs 相关。然而，TCRB 基因座的重复性质和不完全的基因组组装过去一直阻碍了对 TRBV 多态性的评估。
我们使用一种从外周血总 RNA 中对重排的 TCRB 链进行长扩增子下一代测序的新方法，评估了在接受癌症免疫治疗的患者中 TRBV 多态性与 irAEs 之间的联系。我们采用多重 PCR 来创建跨越三个β链互补决定区（CDR）区域的扩增子，以能够检测到种系编码框架内以及 CDR1 和 CDR2 区域内的多态性，此外还能对 CDR3 进行分析。通过 Ion Torrent 对生成的扩增子进行测序，并构建每个个体的 TRBV 等位基因谱，将其与 irAE 注释相关联，以确定与严重 irAEs（≥3 级）相关的单倍型。
我们的研究包括 81 名在接受癌症免疫治疗时出现 irAEs 的患者。通过对 81 个 TRBV 等位基因谱进行主成分分析，然后进行 k-均值聚类，我们确定了六个主要的 TRBV 单倍型。引人注目的是，我们发现该队列中有三分之一的人具有一种 TRBV 等位基因单倍型，似乎可以预防严重的 irAEs。
数据表明，长扩增子 TCRB 库测序可能能够识别与严重 irAEs 风险相关的 TRBV 单倍型组。种系编码的 TRBV 多态性可能作为严重 irAEs 的预测生物标志物。
