Abstract
BackgroundInterleukin-13 receptor α 2 (IL13Rα2) is a promising tumor-directed antigen of malignant glioma (MG). Here, we examine the efficacy and safety of T cells containing a YYB-103 chimeric antigen receptor (CAR) that can preferentially bind to IL13Rα2 on MG cells.MethodsIL13 was modified on the extracellular domain by substitution of amino acids with E13K, R66D, S69D, and R109K and stably transfected into human T cells using a retroviral vector. The in vitro efficacy of YYB-103 CAR T cells was tested in cell lines with differing IL13Rα1 and IL13Rα2 expression. The in vivo efficacy of intracerebroventricular (i.c.v.) and intravenous (i.v.) routes of YYB-103 CAR T-cell administration were tested in orthotopic MG mouse models. Immunohistochemical staining of MG was performed using WHO grade 3/4 surgical specimens from 53 patients. IL13Rα2 expression was quantified by H-score calculated from staining intensity and percentage of positive cells.ResultsBinding affinity assay of YYB-103 verified apparently nil binding to IL13Rα1, which was more selective than previously reported IL13 modification (E13Y). YYB-103 CAR T cells showed selective toxicity toward co-cultured U87MG (IL13Rα1+/IL13Rα2+) cells but not A431 (IL13Rα1+/IL13Rα2−) cells. Consistently, YYB-103 CAR T cells suppressed tumor growth in nude mice receiving orthotopic injection of U87 MG cells. Both i.c.v. and i.v. injections of YYB-103 CAR T cells reduced tumor volume and prolonged overall survival of tumor-bearing mice. The median H-score for IL13Rα2 in patient-derived MG tissue was 5 (mean, 57.5; SD, 87.2; range, 0 to 300).ConclusionThis preclinical study demonstrates the efficacy of IL13Rα2-targeted YYB-103 CAR T cells against MG cells. The use of modified IL13 to construct a CAR facilitated the selective targeting of IL13Rα2-expressing MG cells while sparing IL13Rα1-expressing cells. Notably, YYB-103 CAR T cells exhibited effective blood–brain barrier crossing, suggesting compatibility with i.v. administration rather than intracranial injection. Additionally, the high H-score for IL13Rα2 in glioblastoma, especially in conjunction with the poor prognostic markers of wild-type isocitrate dehydrogenase-1 (IDH-1) and unmethylated O 6-methyl guanine methyl-transferase (MGMT), could be used to determine the eligibility of patients with recurrent glioblastoma for a future clinical trial of YYB-103 CAR T cells.
Highlights
Malignant glioma (MG) is a common and devastating primary brain tumor that leads to death in most cases [1]
YYB-103 contains a modified IL13 with substituted amino acids as an antigen-binding domain to increase its selectivity for the target protein Interleukin-13 receptor a2 (IL13Ra2) while reducing its binding affinity for IL13Ra1 expressed on normal cells
To determine whether YYB-103 was normally expressed in human T cells, we transduced YYP-103 into human T cells and performed Western blotting with anti-CD3z monoclonal antibody using cell lysates from cultured YYB-103 chimeric antigen receptor (CAR)
Summary
Malignant glioma (MG) is a common and devastating primary brain tumor that leads to death in most cases [1]. The development of specific immunotherapies against targeted tumor cells is a promising approach to treating MG [3]. Interleukin-13 receptor a2 (IL13Ra2) is a promising target due to its abundant and specific expression in MG relative to low-grade glioma or normal brain tissue [5,6,7,8]. When IL13Ra2 is expressed, IL13 binds to IL13Ra2 with higher affinity, thereby inhibiting IL13Ra1/IL4R signaling. Such a mechanism is known to induce tumor metastasis and inhibit apoptosis, thereby inducing tumor malignancy. Interleukin-13 receptor a 2 (IL13Ra2) is a promising tumor-directed antigen of malignant glioma (MG). We examine the efficacy and safety of T cells containing a YYB-103 chimeric antigen receptor (CAR) that can preferentially bind to IL13Ra2 on MG cells
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