Objective: KRAS gene is one of the most common mutations of proto-oncogenes in human tumors, G12V is one of the most common mutation types for KRAS. It's challenging to chemically acquire the targeted drug for this mutation. Recent studies reported that this mutation peptides can form a neoepitope for T cell recognition. Our study aims to clone the T cell receptor (TCR) which specifically recognizes the neoepitope for KRAS G12V mutation and constructs TCR engineered T cells (TCR-T), and to investigate if TCR-Ts have strong antitumor response ability.
Methods: In this study, tumor infiltrating lymphocytes were obtained from one colorectal cancer patient carrying KRAS G12V mutation. Tumor-reactive TCR was obtained by single-cell RT-5' rapid-amplification of cDNA ends PCR analysis and introduced into peripheral blood lymphocytes to generate TCR-Ts.
Results: We obtained a high-affinity TCR sequence that specifically recognized the HLA-A*11:01-restricted KRAS G12V8-16 epitope: KVA11-01. KVA11-01 TCR-T could significantly kill various tumor cells such as PANC-1, SW480 and HeLa (overexpressing HLA-A*11:01 and KRAS G12V), and secreting high levels of interferon-γ (IFN-γ). Non-specific killing experiments suggested KVA11-01 specifically recognized tumor cells expressing both mutant KRAS G12V and HLA-A*11:01. In vivo assay, tumor inhibition experiments demonstrated that infusion of approximately 1E7 KVA11-01 TCR-T could significantly inhibit the growth of subcuta-neously transplanted tumors of PANC-1 and HeLa (overexpressing HLA-A*11:01 and KRAS G12V) cells in nude mice. No destruction of the morphologies of the liver, spleen and brain were observed. We also found that KVA11-01 TCR-T could significantly infiltrate into tumor tissue and had a better homing ability.
Conclusion: KVA11-01 TCR-T cells can effectively target a variety of malignant tumor cells carrying KRAS G12V mutation through in vitro and in vivo assay. KVA11-01 TCR-T cells have excellent biological activity, high specificity of target antigen and homing ability into solid tumor tissue. KVA11-01 TCR-T is expected to be an effective treatment for patients with KRAS G12V mutant solid malignancies.
目的: KRAS G12V是最为常见的KRAS突变类型之一，是一个T细胞表位抗原，目前尚无针对该位点的靶向药物，本研究旨在克隆能够特异性识别该表位抗原的T细胞受体(T cell receptor, TCR)，通过体内外实验对该TCR基因修饰T细胞(TCR engineered T cells, TCR-T)靶向KRAS G12V突变肿瘤的安全性和有效性进行评估。
方法: 从1例结直肠癌患者的肿瘤浸润淋巴细胞中获得靶向KRAS G12V8-16表位的高亲和力TCR序列，构建该TCR慢病毒载体并感染人源T细胞，获得TCR-T。采用抗原肽激活、γ-干扰素(interferon-γ, IFN-γ) 酶联免疫吸附试验(enzyme linked immunosorbent assay，ELISA)、T细胞体外增殖等实验，体外评价该TCR-T的免疫杀伤活性和脱靶-交叉反应性；通过体内实验评价该TCR-T的抑瘤效果、安全性等指标。
结果: 获得了能特异性识别HLA-A*11：01限制性KRAS G12V8-16表位的高亲和力TCR序列KVA11-01。KVA11-01 TCR-T能够显著杀伤体外过表达HLA-A*11:01和KRAS G12V的多种肿瘤细胞。非特异杀伤实验显示，KVA11-01仅杀伤同时表达HLA-A*11:01和KRAS G12V的肿瘤细胞。体内抑瘤实验显示，KVA11-01 TCR-T可以显著抑制PANC-1和HeLa(体外过表达HLA-A*11:01和KRAS G12V)细胞裸鼠皮下移植瘤的生长。TCR-T细胞可以显著浸润至肿瘤组织内部，有良好的实体肿瘤归巢能力。
结论: KVA11-01 TCR-T能够在体内外有效靶向并杀伤携带KRAS G12V突变的多种恶性肿瘤细胞，具有良好的实体瘤组织归巢能力，KVA11-01 TCR-T有望成为携带KRAS G12V突变的实体恶性肿瘤患者的有效治疗手段。
Keywords: DNA mutational analysis; Neoplasms; T-cell receptor; Tumor-infiltrating lymphocytes.