EXTH-72. TRANSLATIONAL INVESTIGATION OF TD139 FOR THE TREATMENT OF HIGH-GRADE MENINGIOMA

Abstract

Abstract BACKGROUND High-Grade Meningioma (HGM), such as atypical and anaplastic meningiomas, represent a subgroup of meningiomas with histologic and clinical features suggesting aggressive behavior with a penchant for recurrence, even after surgical resection. Here, we postulate that high levels of Galectin-3 (Gal-3) affect the cellular composition and are at the root of the profoundly immunosuppressive tumor microenvironment of HGM. Our study aimed to validate the effect of the Gal-3 inhibitor (TD139) in in vivo. METHODS In vivo MGS2 murine models of HGM were utilized to assess efficacy of treatment with TD139 via intravenous injection. We used ELISA spot, RT-PCR and western blots techniques. MRI and immunohistochemistry -staining methods were used to detect tumor growth in in vivo following TD139 treatments. RESULTS Our results demonstrated a significantly elevated level of Gal-3 in both HGM tissue and serum when compared to non-tumor patients. Furthermore, Epithelial membrane antigen, Ki-67, and Transglutaminase 2 were highly expressed in HGM, whereas the number of observed cytotoxic T-cells in HGM was markedly decreased. When human PBMCs were activated with anti-CD3 (1µg/ml) and anti-CD28 (2µg/ml) antibodies and treated with recombinant Gal-3 protein (500ng/ml) for 96hr, we found reduced expression of T-Box Transcription Factor 21 and RAR Related Orphan Receptor C mRNA with concurrent upregulated expression of GATA Binding protein 3 and Forkhead box P3 mRNA. These findings support the concept that Gal-3 skews the differentiation of CD4+ T cells towards Th2 and Treg cells. In vivo treatment of TD139 (1mg/kg per day for 14 days) showed significant decrease (∼35%) in MGS2 tumor growth in orthotopic allograft model (at Day 41) and increased survival via multiple mechanism. Additionally, we observed an upregulation of CD38 (M1 macrophages) and CD8+ T cells in treated cells. CONCLUSIONS These findings suggest that TD139 may be an effective approach in the treatment of HGM patients.