Dagvadorj Nergui, Deuretzbacher Anne, Weisenberger Daniela, Baumeister Elke, Trebing Johannes, Lang Isabell, Köchel Carolin, Kapp Markus, Kapp Kerstin, Beilhack Andreas, Hünig Thomas, Einsele Hermann, Wajant Harald, Grigoleit Götz Ulrich
Laboratory for Immunotherapy, Department of Internal Medicine II, University Hospital of Würzburg, Josef-Schneider-Str. 2, 97080, Würzburg, Germany.
Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia.
Cancer Immunol Immunother. 2017 Mar;66(3):319-332. doi: 10.1007/s00262-016-1938-y. Epub 2016 Nov 28.
Due to its immunogenicity and overexpression concomitant with leukemia progression, Wilms tumor protein 1 (WT1) is of particular interest for immunotherapy of AML relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). So far, WT1-specific T-cell responses have mainly been induced by vaccination with peptides presented by certain HLA alleles. However, this approach is still not widely applicable in clinical practice due to common limitations of HLA restriction. Dendritic cell (DC) vaccines electroporated with mRNA encoding full-length protein have also been tested for generating WT1-derived peptides for presentation to T-cells. Alternatively, an efficient and broad WT1 peptide presentation could be elicited by triggering receptor-mediated protein endocytosis of DCs. Therefore, we developed antibody fusion proteins consisting of an antibody specific for the DEC205 endocytic receptor on human DCs and various fragments of WT1 as DC-targeting recombinant WT1 vaccines (anti-hDEC205-WT1). Of all anti-hDEC205-WT1 fusion proteins designed for overcoming insufficient expression, anti-hDEC205-WT1, anti-hDEC205-WT1, anti-hDEC205-WT1, and anti-hDEC205-WT1 were identified in good yields. The anti-hDEC205-WT1 was capable of directly inducing ex vivo T-cell responses by co-incubation of the fusion protein-loaded monocyte-derived mature DCs and autologous T-cells of either healthy or HSCT individuals. Furthermore, the DC-targeted WT1-induced specific T-cells showed a strong cytotoxic activity by lysing WT1-overexpressing THP-1 leukemia cells in vitro while sparing WT1-negative hematopoietic cells. In conclusion, our approach identifies four WT1 peptide-antibody fusion proteins with sufficient production and introduces an alternative vaccine that could be easily translated into clinical practice to improve WT1-directed antileukemia immune responses after allo-HSCT.
由于威尔姆斯瘤蛋白1（WT1）具有免疫原性且其过表达与白血病进展相伴，它在异基因造血干细胞移植（allo-HSCT）后急性髓系白血病（AML）复发的免疫治疗中备受关注。到目前为止，WT1特异性T细胞反应主要通过接种由某些HLA等位基因呈递的肽来诱导。然而，由于HLA限制的常见局限性，这种方法在临床实践中仍未广泛应用。用编码全长蛋白的mRNA电穿孔的树突状细胞（DC）疫苗也已被测试用于产生WT1衍生的肽以呈递给T细胞。另外，通过触发DC的受体介导的蛋白内吞作用可以引发高效且广泛的WT1肽呈递。因此，我们开发了由针对人DC上DEC205内吞受体的抗体与WT1的各种片段组成的抗体融合蛋白，作为DC靶向重组WT1疫苗（抗hDEC205-WT1）。在为克服表达不足而设计的所有抗hDEC205-WT1融合蛋白中，抗hDEC205-WT1、抗hDEC205-WT1、抗hDEC205-WT1和抗hDEC205-WT以良好的产量被鉴定出来。抗hDEC205-WT1能够通过将负载融合蛋白的单核细胞衍生的成熟DC与健康或HSCT个体的自体T细胞共同孵育来直接诱导体外T细胞反应。此外，DC靶向的WT1诱导的特异性T细胞在体外裂解WT1过表达的THP-1白血病细胞时表现出强大的细胞毒性活性，同时不损伤WT1阴性造血细胞。总之，我们的方法鉴定出四种产量充足的WT1肽-抗体融合蛋白，并引入了一种可轻松转化为临床实践的替代疫苗，以改善allo-HSCT后针对WT1的抗白血病免疫反应。
