EXTH-54. COMBINATORIAL DRUG SCREENING IDENTIFIES CARFILZOMIB AND ENZALUTAMIDE FOR TREATING AGGRESSIVE MENINGIOMAS

Abstract The goal of combinatorial therapy is to improve the effectiveness of treatment by targeting multiple aspects of cancer cells or overcoming resistance to single drugs. Therefore, we performed an automated combinatorial drug screening in meningioma cell lines and patient-derived tumor organoids (TOs). Three grade 3 meningioma cell lines (NCH93, IOMM-Lee, and KT21-MG1) were stably transduced with blue, green, and red fluorescence proteins. The cell lines were multiplexed into 384-well plates and treated in 5x5 dose-response (0-1000 nmol/l) matrices for 48h by the automated liquid handler Hamilton MicroLAB STAR®. The drug library consisted of 166 FDA-approved anticancer drugs. The viability of each cell line was demultiplexed by using fluorescence signals and CellTiterGlo. TOs were established from single cell suspensions of freshly resected meningioma tissue (n=20). The ZIP model was used to determine synergism. This drug screening effort generated 13,695 unique drug-drug combinations per cell line. Most synergistic combinations were observed in IOMM-Lee (1.14%), followed by KT21-MG1 (0.88%), and NCH93 (0.54%). The 110 most effective drug combinations were validated in wild-type meningioma cells. 75 drug combinations demonstrated a positive most synergistic area (MSA) score, indicating synergistic effects. Based on synergy scores and literature evidence, the 16 most promising combinations were selected for screening in TOs. The proteasome inhibitor carfilzomib in combination with the androgen receptor inhibitor enzalutamide exhibited the highest synergy in TOs. In 40% (n=8/20) of the cases, the combination showed strong synergism (MSA>10) resulting in an overall average MSA of 7.36, followed by carfilzomib and neratinib, and romidepsin and gemcitabine with average MSAs of 5.49, and 4.32, respectively. Furthermore, carfilzomib and enzalutamide induced apoptosis in TOs assessed by Caspase-3/7. This comprehensive combinatorial drug screening identified the synergistic combination of the proteasome inhibitor carfilzomib and androgen receptor inhibitor enzalutamide that can be an effective treatment option for selected meningioma patients.