ATRT-13. Targeting the NF-kB pathway in AT/RT using combined ixazomib and quinacrine drug therapy

Atypical teratoid and rhabdoid tumor (AT/RT) is a highly malignant pediatric brain cancer that currently lacks therapeutic options. AT/RT is an epigenetically driven cancer with widespread signaling pathway dysregulation, one of which is the inflammatory NF-κB pathway. Ixazomib is an oral proteasome inhibitor clinically approved to treat multiple myeloma and works by suppressing the NF-κB pathway. Quinacrine, an anti-malarial drug with anticancer activity, also prevents NF-κB activity through “trapping” the Facilitates Chromatin Transcription (FACT) complex in DNA. Previous research show that quinacrine and ixazomib both induce apoptosis and suppress proliferation in AT/RT cells as single-agent therapies, but their impact on the NF-κB pathway in AT/RT remains unknown. We hypothesize that combining ixazomib and quinacrine will induce a synergistic effect and prevent AT/RT tumorigenesis through targeting NF-κB. We treated AT/RT cell-line CHLA06 using both single-agent and combinatory groups of ixazomib and quinacrine at various dosages determined by their IC50s. Cleaved caspase-3 immunofluorescence showed increased cell apoptosis in combination compared to vehicle (p = 0.0001) and compared to single-agent therapies (p = 0.003 for ixazomib, p = 0.0004 for quinacrine using ANOVA and Tukey’s multiple comparisons test). Western blotting further demonstrated that the combined drugs induced greater apoptosis based on increased cleaved PARP activity. It also showed decreased IκBα, a NF-κB-specific downstream transcriptional target, in combination groups. Our results suggest that ixazomib and quinacrine have a synergistic effect on AT/RT cell death due to NF-κB suppression. Future experiments involve extending treatments to other AT/RT cell-lines and transfecting cells with a NF-κB luciferase construct to further assess NF-κB activity in vitro. We will treat AT/RT orthotopic xenograft models using both drugs. This study can lead to the development of novel therapeutics to improve treatment for children affected by AT/RT.