VEGFR2 as a target for CAR T cell therapy of Ewing sarcoma

Abstract

Background T cells engineered to express chimeric antigen receptors (CARs) are a novel modality to treat refractory cancers. The development of CAR T cells against Ewing sarcoma (EwS) is limited by a lack of targetable surface antigens. We investigated vascular endothelial growth factor receptor 2 (VEGFR2) expressed on tumor‐associated blood vessels as potential CAR target in this cancer. Methods Expression of VEGFR2 was studied by immunohistochemistry in human EwS biopsies and in murine xenografts and by flow cytometry in EwS cell lines. CARs with short, medium, and long hinge domains against either human or murine VEGFR2 were generated and expressed in human T cells by retroviral gene transfer. The capacity of the individual CARs to activate T cells in response to VEGFR2‐expressing cells was compared in vitro. Results Tumor‐associated endothelial cells in human EwS biopsies and in xenografts expressed VEGFR2. Tumor cells in the majority of EwS biopsies were also VEGFR2‐positive. Following modification with anti‐mouse or anti‐human VEGFR2‐specific CAR genes, T cells specifically lysed VEGFR2‐expressing target cells of the respective species. CAR T cells with short‐length or medium‐length hinge domains were functionally superior over those with the long hinge region by in vitro parameters, including antigen‐specific degranulation responses, lysis of tumor spheroids, tumor necrosis factor α secretion, sequential killing, and proliferation. Conclusions VEGFR2 is consistently expressed on endothelial cells of the tumor stroma in EwS and thus is a candidate target for CAR T cells in this cancer. Among various VEGFR2‐specific CARs, a construct with a short hinge domain was chosen to be further developed toward clinical translation.

A Novel Treatment for Ewing’s Sarcoma: Chimeric Antigen Receptor-T Cell Therapy

“…In one study, researchers generated CAR constructs against both human and murine VEGFR2 to enable preclinical studies of the xenograft model of EWS. This study showed that VEGFR2specific CAR-T cells effectively lysed VEGFR2-positive cells of the respective species and responded with potent antigen-specific degranulation responses, cytokine secretion, and proliferation (20). Thus, VEGFR2 is likely to be a suitable target for CAR-T cell therapy in EWS.…”

Advances in CAR-T Cell Genetic Engineering Strategies to Overcome Hurdles in Solid Tumors Treatment

“…These results emphasize the advantageous effects of dual targeting adoptive therapy including an anti-angiogenic strategy ( 88 ). Recently, Englisch et al suggested that VEGFR-2 expressed on tumor vasculature could be a potential CAR target in Ewing sarcoma (EwS) ( 89 ), especially that this type of cancer is characterized by a limited TSA expression on cancer cells ( 90 ). Contact with their target triggered a powerful antigen‐specific degranulation response, increased proliferation and cytokine secretion of VEGFR-2 CAR-T cells.…”

“…Contact with their target triggered a powerful antigen‐specific degranulation response, increased proliferation and cytokine secretion of VEGFR-2 CAR-T cells. Data showed that VEGFR-2 CAR-T cells with short‐length or medium‐length hinge domains effectively destroyed VEGFR-2-expressing tumor‐associated endothelial cells ( 89 ). Similarly, in a study from Taheri et al nanobody‐based anti-VEGFR2 CAR showed effective activation, degranulation and lysis of VEGFR2+ cell lines in an in vitro model ( 91 ).…”

CAR T Cell Locomotion in Solid Tumor Microenvironment

“…Although mechanisms of TEM have been reported extensively, identification of a comprehensible approach to enhance the extravasation of T cells remains elusive. Instead, T cells have been engineered to target tumor-associated endothelial receptors such as VEGFR2 to disrupt tumor-supporting vasculature, enhance T cell trafficking, and deprive the tumor of nutrient and oxygen supplies [ 15 , 16 ]. This approach revealed the efficient killing of in vitro tumor spheroids [ 16 ] and prolonged survival in animal models [ 15 , 17 , 18 ].…”