Co-treatment of human GBM cell lines with imipridone ONC206 and tumor treating fields: Effect on on cell death and p-AKT.

e14033 Background: Glioblastoma (GBM) is the most common primary brain malignancy with dismal prognosis. Tumor Treating Fields (TTFields) therapy is available for the treatment of both newly diagnosed and recurrent glioblastoma and represents a new category of treatment modalities in oncologic therapy. Despite decades of study, few FDA approved modalities are available for GBM and provide limited survival improvements for patients. AKT functions as a key serine/threonine kinase in the RTK/PTEN/PI3K pathway, and extensive genomic analysis of GBM has revealed that this pathway is mutated in a significant majority of GBM cases. Activation of this pathway ultimately leads to the activation of AKT, and phospho-AKT levels are elevated in the majority of GBM tumor samples and cell lines. Studies have shown that increased p-AKT levels contribute to uncontrolled growth, resistance to apoptosis, and enhanced invasive capabilities of glioma cells, which are characteristics of tumor progression in GBM. AKT serves as a critical hub in this pathway, enabling the amplification of growth signals, thereby making the inhibition of AKT an appealing and promising therapeutic target for treating GBM. Imipridone ONC206 is under clinical development for treatment of pediatric and adult patients with primary brain tumors (NCT04732065 and NCT04541082). Here we show inhibition of p-AKT as well as upregulation of cleaved PARP following cotreatment of ONC206 and TTFields. Methods: We investigated the effect of ONC206 at IC50s plus TTFields in LN229, U138, U251 and T98G human GBM cell lines at different time points. Effect of treatment on cPARP, BCL-2, CHOP, caspase-10, and p-AKT were investigated using western blot. Results: Treatment with ONC206 at the IC50 in T98G cells with TTFields at 24h showed synergistic upregulation of cPARP as well as inhibition of BCL-2. At 96hour time point, inhibition of p-AKT was observed following all treatments (ONC206, TTFields, and co-application compared to control. In U251 cells, following treatment of ONC206 and TTFields, inhibition of BCL-2 was observed at 24h time point. Upregulation of CHOP and Casapse-10 at 96h time point was seen, as well as inhibition of p-AKT. Spheroid models showed structure disruption and growth arrest following combination treatment. At 72 h time point co treatment with ONC206 and TTFields resulted in synergistic upregulation of cleaved PARP. Conclusions: Here we showed cotreatment with TTFields and ONC206 results in inhibition of p-AKT, the key node in GBM growth pathway. This is the first report of cleaved PARP upregulation following TTFields and ONC206 in Human GBM cell line. Further studies to investigate the in vivo efficacy of TTField treatment in GBM with ONC206 are warranted. More studies are needed to understand the exact mechanism of synergy.