目前治疗急性髓系白血病 (AML) 的药物疗法仍未得到满足，而 AML 患者可能会受益于针对特定肿瘤抗原的靶向免疫治疗方法。 GRP78在多种恶性肿瘤（例如AML）中表达上调，部分表达为细胞膜上的细胞表面GRP78（csGRP78），使其成为重定向T细胞（包括T细胞接合器）的理想靶标。然而，考虑到使用两个 scFv 片段构建双特异性 T 细胞接合器 (BiTE) 的传统方法，我们开发了一种新型 BiTE，它利用环肽配体特异性靶向 csGRP78，我们将其称为 GRP78- CD3/BiTE。我们研究了 GRP78-CD3/BiTE 对 AML 体外和体内治疗的影响，并评估了该接合剂的药代动力学。我们的研究结果表明，GRP78-CD3/BiTE不仅可以有效介导T细胞对表达csGRP78的AML细胞的细胞毒性，而且可以在体外特异性消除原代AML肿瘤细胞。此外，尽管 GRP78-CD3/BiTE 的分子量低于 CD19-CD3/BiTE，但其半衰期更长。在 AML 异种移植小鼠模型中，GRP78-CD3/BiTE 治疗延长了小鼠的生存时间。我们的研究结果表明，GRP78-CD3/BiTE 可有效且选择性地消除表达 csGRP78 的 AML 细胞，并表明这种靶向免疫治疗方法可能会带来有效的 AML 新疗法。© 2024。作者。

Current medical therapies for treating acute myeloid leukemia (AML) remain unmet, and AML patients may benefit from targeted immunotherapy approaches that focus on specific tumor antigens. GRP78, which is upregulated in various malignant tumors such as AML, is partially expressed as cell surface GRP78 (csGRP78) on the cell membrane, making it an ideal target for redirecting T cells, including T-cell engagers. However, considering the conventional approach of using two scFv segments to construct a bispecific T-cell engager (BiTE), we have undertaken the development of a novel BiTE that utilizes a cyclic peptide ligand to specifically target csGRP78, which we refer to as GRP78-CD3/BiTE. We studied the effects of GRP78-CD3/BiTE on treatments for AML in vitro and in vivo and assessed the pharmacokinetics of this engager. Our findings demonstrated that GRP78-CD3/BiTE could not only effectively mediate the cytotoxicity of T cells against csGRP78-expressing AML cells but also specifically eliminate primary AML tumor cells in vitro. Furthermore, GRP78-CD3/BiTE exhibited a longer half-life despite having a lower molecular weight than CD19-CD3/BiTE. In a xenograft mouse model of AML, treatment with GRP78-CD3/BiTE prolonged the survival time of the mice. Our findings demonstrate that GRP78-CD3/BiTE is effective and selective for eliminating csGRP78-expressing AML cells and suggest that this approach to targeted immunotherapy could lead to effective new treatments for AML.© 2024. The Author(s).