Robust antitumor activity of a de novo interleukin-21 mimic

A long-standing goal of cancer immunotherapy is to activate cytotoxic antitumor T cells across a broad range of affinities and dampen suppressive regulatory T (Treg) cell responses, but current approaches achieve these goals with limited success. Here, we report a de novo IL-21 mimic, 21h10, designed to have augmented stability and high signaling potency in both humans and mice. In multiple animal models, 21h10 showed robust antitumor activity, exceeding that of native IL-21 for murine melanoma, inducing a rapid regression of murine adenocarcinoma, and exhibiting potent activity in an orthotopic pancreatic cancer model that is refractory to conventional immunotherapies. In the tumor microenvironment, 21h10 induced highly cytotoxic antitumor T cells from clonotypes with a range of affinities for endogenous tumor antigens, driving high expression of interferon-𝛾 (IFN-𝛾) and granzyme B compared to native IL-21, while in the CD4+ T cell compartment, the frequency of IFN-𝛾+ Th1 cells was increased while Foxp3+ Treg cells were reduced. Thus, 21h10 is a highly active IL-21 mimic with human-mouse cross-reactivity that potentiates low-affinity antitumor responses and has considerable translational potential. RNA-Seq analyses using mouse CD8+ T cells that were pre-activated with anti-CD3 + anti-CD28, and cultured in complete RPMI media for 48 hours at 37°C. Cells were rested overnight, and then either without stimulation or stimulated with either mIL-21 or 21h10 for 24h.

癌症免疫治疗的长期目标之一，是激活具有广泛亲和力的细胞毒性抗肿瘤T细胞，并抑制免疫抑制性调节性T（Treg）细胞的应答，但当前相关方法在实现上述目标时成效有限。本研究报道了一种全新的IL-21模拟物21h10，其经设计后可增强稳定性，且在人类与小鼠体内均展现出高信号转导活性。在多种动物模型中，21h10展现出强效的抗肿瘤活性：针对小鼠黑色素瘤，其活性优于天然IL-21；可诱导小鼠腺癌快速消退；且在对常规免疫治疗难治的原位胰腺癌模型中亦表现出显著活性。在肿瘤微环境中，相较于天然IL-21，21h10可从对内源性肿瘤抗原具有不同亲和力的克隆型中诱导出高细胞毒性的抗肿瘤T细胞，驱动干扰素-γ（IFN-γ）与颗粒酶B的高表达；在CD4+ T细胞亚群中，IFN-γ+ Th1细胞的频率得以提升，而Foxp3+ Treg细胞的数量则有所减少。综上，21h10是一种兼具人鼠交叉反应性的高活性IL-21模拟物，可增强低亲和力抗肿瘤应答，具备可观的转化研究潜力。本研究采用经抗CD3+抗CD28预激活、并于37℃下在完全RPMI培养基中培养48小时的小鼠CD8+ T细胞开展RNA-Seq分析：将细胞静置过夜后，分别施以无刺激、小鼠IL-21或21h10刺激，持续24小时。