Department of Medical Oncology, Oncode Institute, Leiden University Medical Centre (LUMC), Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Geert Grooteplein 26, 6525 GA Nijmegen, The Netherlands.
Int J Mol Sci. 2022 Aug 5;23(15):8707. doi: 10.3390/ijms23158707.
Regulatory T cells (T) are major drivers behind immunosuppressive mechanisms and present a major hurdle for cancer therapy. T are characterized by a high expression of CD25, which is a potentially valuable target for T depletion to alleviate immune suppression. The preclinical anti-CD25 (αCD25) antibody, clone PC-61, has met with modest anti-tumor activity due to its capacity to clear T from the circulation and lymph nodes, but not those that reside in the tumor. The optimization of the Fc domain of this antibody clone has been shown to enhance the intratumoral T depletion capacity. Here, we generated a stable cell line that produced optimized recombinant T-depleting antibodies. A genome engineering strategy in which CRISPR-Cas9 was combined with homology-directed repair (CRISPR-HDR) was utilized to optimize the Fc domain of the hybridoma PC-61 for effector functions by switching it from its original rat IgG1 to a mouse IgG2a isotype. In a syngeneic tumor mouse model, the resulting αCD25-m2a (mouse IgG2a isotype) antibody mediated the effective depletion of tumor-resident T, leading to a high effector T cell (T) to T ratio. Moreover, a combination of αCD25-m2a and an αPD-L1 treatment augmented tumor eradication in mice, demonstrating the potential for αCD25 as a cancer immunotherapy.
调节性 T 细胞（T 细胞）是免疫抑制机制的主要驱动因素，也是癌症治疗的主要障碍。T 细胞的特征是高表达 CD25，这是 T 细胞耗竭的潜在有价值的靶点，可减轻免疫抑制。临床前抗 CD25（αCD25）抗体克隆 PC-61 由于其能够从循环和淋巴结中清除 T 细胞，但不能清除肿瘤内的 T 细胞，因此具有适度的抗肿瘤活性。该抗体克隆的 Fc 结构域的优化已被证明可增强肿瘤内 T 细胞耗竭能力。在这里，我们生成了一种稳定的细胞系，该细胞系产生了优化的重组 T 细胞耗竭抗体。我们利用一种基因组工程策略，将 CRISPR-Cas9 与同源定向修复（CRISPR-HDR）相结合，通过将杂交瘤 PC-61 的 Fc 结构域从原始大鼠 IgG1 切换为小鼠 IgG2a 同种型，从而优化其效应功能。在同种异体肿瘤小鼠模型中，产生的 αCD25-m2a（小鼠 IgG2a 同种型）抗体介导了肿瘤内驻留 T 细胞的有效耗竭，导致效应 T 细胞（T 细胞）与 T 细胞的比例很高。此外，αCD25-m2a 与 αPD-L1 联合治疗增强了小鼠的肿瘤清除，表明 αCD25 作为癌症免疫疗法的潜力。
