Pilbeam Kristy, Wang Hongbo, Taras Elizabeth, Bergerson Rachel J, Ettestad Brianna, DeFor Todd, Borgatti Antonella, Vallera Daniel A, Verneris Michael R
Pediatric Blood and Marrow Transplantation, University of Minnesota, Minneapolis, MN 55345, USA.
Radiation Oncology, University of Minnesota, Minneapolis, MN 55345, USA.
Oncotarget. 2017 Sep 23;9(15):11938-11947. doi: 10.18632/oncotarget.21187. eCollection 2018 Feb 23.
Children with high risk sarcoma have a poor prognosis despite surgical resection, irradiation and chemotherapy. Alternative therapies are urgently needed. Urokinase-type plasminogen activator receptor (uPAR) and epidermal growth factor receptor (EGFR) are surface proteins expressed by some pediatric sarcomas. We show for the first time that a de-immunized bispecific ligand toxin, EGFATFKDEL, directed against EGFR and uPAR, successfully targets pediatric sarcoma. Using flow cytometry, we identified a rhabdomyosarcoma (RMS) cell line, RH30, that expresses both uPAR and EGFR, and a Ewing sarcoma (EWS) cell line, TC-71, that expresses only uPAR. We tested the differential sensitivity of these two sarcoma cell lines to toxin-induced killing, using both assays and an murine model. We show that pediatric sarcomas are highly sensitive to EGFATFKDEL (at subnanomolar concentrations) . , tumor growth was significantly attenuated after treatment with EGFTFKDEL, compared to untreated controls, in both RH30 and TC-71 tumor bearing mice. In addition, we found that simultaneously targeting both receptors in a dual positive cell line was more effective than targeting a single receptor or antigen, resulting in a greater tumor response, including complete tumor regression in an animal model of bulky disease. Our findings provide support for further exploration of bispecific targeting of pediatric sarcomas with bispecific ligand toxins, such as EGFATFKDEL.
尽管进行了手术切除、放疗和化疗，高危肉瘤患儿的预后仍然很差。迫切需要替代疗法。尿激酶型纤溶酶原激活物受体（uPAR）和表皮生长因子受体（EGFR）是一些儿童肉瘤表达的表面蛋白。我们首次表明，一种去免疫的双特异性配体毒素EGFATFKDEL，靶向EGFR和uPAR，成功地靶向了儿童肉瘤。通过流式细胞术，我们鉴定出一种同时表达uPAR和EGFR的横纹肌肉瘤（RMS）细胞系RH30，以及一种仅表达uPAR的尤因肉瘤（EWS）细胞系TC-71。我们使用两种检测方法和一种小鼠模型，测试了这两种肉瘤细胞系对毒素诱导杀伤的差异敏感性。我们表明，儿童肉瘤对EGFATFKDEL（在亚纳摩尔浓度下）高度敏感。例如，与未治疗的对照组相比，在用EGFTFKDEL治疗后，RH30和TC-71荷瘤小鼠的肿瘤生长均显著减弱。此外，我们发现，在双阳性细胞系中同时靶向两种受体比靶向单一受体或抗原更有效，导致更大的肿瘤反应，包括在大块疾病动物模型中肿瘤完全消退。我们的研究结果为进一步探索用双特异性配体毒素（如EGFATFKDEL）对儿童肉瘤进行双特异性靶向治疗提供了支持。
