Wan Yuhua, Zhang Yan, Wang Gengchong, Mwangi Patrick Malonza, Cai Huaman, Li Rongxiu
State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Shanghai HyCharm Inc., Shanghai, China.
Front Oncol. 2020 Aug 12;10:1326. doi: 10.3389/fonc.2020.01326. eCollection 2020.
Drug development targeting the most frequently mutation G12D of KRAS has great significance. As an attractive immunotherapy, cancer vaccines can overcome binding difficulties of small molecules; however, the weak immunogenicity and production difficulties of reported KRAS mutation vaccines limit their clinical application. To improve antigen-specific immune responses and Anti-Tumor effects on tumors expressing KRAS G12D mutation, we designed recombinant proteins containing KRAS peptide (amino acids 5-21) with G12D (called SP) in two forms: DTT-SP and DTSP. DTT-SP was constructed by fusing four copies of SP to the C-terminal of the translocation domain of diphtheria toxin (DTT), and DTSP was constructed by grafting SP onto DTT. The two vaccines in combination with aluminum hydroxide (Alum) and cytosine phosphoguanine (CpG) successfully induced conspicuous SP-specific humoral and cellular immune responses, and displayed prominent protective and therapeutic Anti-Tumor effects in mouse CT26 tumor models. Surprisingly, the DTSP-treated group displayed better Anti-Tumor effects compared with the DTT-SP-treated and control groups. Moreover, 87.5 and 50% of DTSP-treated mice in the preventive and therapeutic models were tumor free, respectively. Notably, in the DTSP-treated group, the interferon-γ (IFN-γ) expression of T cells and the T-helper 1 (Th1)-related cytokine expression in tumor tissues indicated that the activated Th1 immune response may be involved in Anti-Tumor activity. Furthermore, DTSP treatment remarkably altered the subpopulation of T cells in splenocytes and tumor-infiltrating lymphocytes. The percentage of effector CD8 T cells increased, whereas that of immunosuppressive CD4Foxp3 T cells remained reduced in the DTSP group. Dramatic tumor-inhibitory effects of DTSP, which is easily prepared, make it a more attractive strategy against KRAS G12D tumors.
针对最常见的KRAS G12D突变进行药物开发具有重大意义。癌症疫苗作为一种有吸引力的免疫疗法，可以克服小分子的结合困难；然而，已报道的KRAS突变疫苗免疫原性弱和生产困难限制了它们的临床应用。为了改善针对表达KRAS G12D突变的肿瘤的抗原特异性免疫反应和抗肿瘤效果，我们设计了两种形式的含有KRAS肽（氨基酸5-21）和G12D的重组蛋白（称为SP）：DTT-SP和DTSP。DTT-SP是通过将四个拷贝的SP融合到白喉毒素（DTT）转位结构域的C末端构建而成，而DTSP是通过将SP嫁接到DTT上构建而成。这两种疫苗与氢氧化铝（明矾）和胞嘧啶磷酸鸟嘌呤（CpG）联合使用，成功诱导了明显的SP特异性体液和细胞免疫反应，并在小鼠CT26肿瘤模型中显示出显著的保护性和治疗性抗肿瘤效果。令人惊讶的是，与DTT-SP处理组和对照组相比，DTSP处理组显示出更好的抗肿瘤效果。此外，在预防和治疗模型中，分别有87.5%和50%的DTSP处理小鼠无肿瘤。值得注意的是，在DTSP处理组中，肿瘤组织中T细胞的干扰素-γ（IFN-γ）表达和辅助性T细胞1（Th1）相关细胞因子表达表明，激活的Th1免疫反应可能参与了抗肿瘤活性。此外，DTSP处理显著改变了脾细胞和肿瘤浸润淋巴细胞中T细胞的亚群。在DTSP组中，效应性CD8 T细胞的百分比增加，而免疫抑制性CD4Foxp3 T细胞的百分比仍然降低。易于制备的DTSP具有显著的肿瘤抑制作用，使其成为对抗KRAS G12D肿瘤更具吸引力的策略。
