Impressive outcomes have been achieved by chimeric antigen receptor (CAR)‐T cell therapy using murine‐derived single‐chain variable fragment (scFv) FMC63 specific for CD19 in patients with B cell malignancies. However, evidence suggests that human anti‐mouse immune responses might be responsible for poor persistence and dysfunction of CAR‐T cells, leading to poor outcomes or early tumor recurrence. Substituting a fully human scFv for murine‐derived scFv may address this clinically relevant concern. In this study, we discovered two human anti‐CD19 scFv candidates through an optimized protein/cell alternative panning strategy and evaluated their function in CAR‐T cells and CD19/CD3 bispecific antibody formats. The two clones exhibited excellent cytotoxicity in CAR‐T cells and bispecific antibodies in vitro compared with the benchmarks FMC63 CAR‐T cells and blinatumomab. Furthermore, Clone 78‐BBz CAR‐T cells exhibited similar in vivo antitumor activity to FMC63‐BBz CAR‐T cells. Our results indicate that Clone 78‐BBz CAR has excellent efficacy and safety profile and is a good candidate for clinical development.

中文翻译：

---

用于 T 细胞治疗的新型全人抗 CD19 嵌合抗原受体的开发和功能表征

使用鼠源性单链可变片段 (scFv) FMC63 特异性针对 B 细胞恶性肿瘤的 CD19 的嵌合抗原受体 (CAR)-T 细胞疗法取得了令人印象深刻的结果。然而，有证据表明，人类抗小鼠免疫反应可能是 CAR-T 细胞持久性差和功能障碍的原因，导致预后不良或早期肿瘤复发。用完全人类的 scFv 代替鼠源性 scFv 可能会解决这一临床相关问题。在这项研究中，我们通过优化的蛋白质/细胞替代淘选策略发现了两种人类抗 CD19 scFv 候选物，并评估了它们在 CAR-T 细胞和 CD19/CD3 双特异性抗体形式中的功能。与基准 FMC63 CAR-T 细胞和 blinatumomab 相比，这两个克隆在体外 CAR-T 细胞和双特异性抗体中表现出优异的细胞毒性。此外，克隆 78-BBz CAR-T 细胞表现出与 FMC63-BBz CAR-T 细胞相似的体内抗肿瘤活性。我们的结果表明，Clone 78-BBz CAR 具有出色的疗效和安全性，是临床开发的良好候选者。