Therapeutic Targeting of TGFβ Ligands in Glioblastoma Using Novel Antisense Oligonucleotides Reduces the Growth of Experimental Gliomas.

Purpose: Transforming growth factor (TGF)-β is expressed at high levels by glioma cells and contributes to the malignant phenotype of glioblastoma. However, its therapeutic targeting remains challenging. Here, we examined an alternative therapeutic approach of TGFβ inhibition using two novel phosphorothioate-locked nucleic acid (LNA)-modified antisense oligonucleotide gapmers, ISTH1047 and ISTH0047, which specifically target TGFβ and TGFβ.

Experimental Design: We characterized the effects of ISTH1047 and ISTH0047 on TGFβ expression, downstream signaling and growth of human LN-308, LN-229, and ZH-161 cells as well as murine SMA-560 glioma cells . Furthermore, we assessed their target inhibition and effects on survival in orthotopic xenogeneic and syngeneic rodent glioma models .

Results: Both antisense oligonucleotides specifically silenced their corresponding target and abrogated SMAD2 phosphorylation in several glioma cell lines. Moreover, inhibition of TGFβ or TGFβ expression by ISTH1047 or ISTH0047 reduced the migration and invasiveness of LN-308 and SMA-560 glioma cells. Systemic antisense oligonucleotide administration to glioma-bearing mice suppressed or mRNA expression as well as the expression of the downstream target in orthotopic gliomas. Glioma-bearing mice had significantly prolonged survival upon systemic treatment with ISTH1047 or ISTH0047, which was associated with a reduction of intratumoral SMAD2 phosphorylation and, in a fully immunocompetent model, with increased immune cell infiltration.

Conclusions: Targeting TGFβ expression with the novel LNA antisense oligonucleotides ISTH1047 or ISTH0047 results in strong antiglioma activity and , which may represent a promising approach to be examined in human patients with glioma.