TMOD-36. SUCCESSFUL GENERATION OF FIVE PATIENT-DERIVED ENDOGENOUS IDH1 MUTANT GLIOMA CELL LINES PROVIDES OPPORTUNITIES FOR DEVELOPMENT OF NEW TREATMENT STRATEGIES FOR IDH MUTANT GLIOMAS

Abstract

Despite the high frequency of IDH mutations in low-grade gliomas and secondary glioblastomas, in vitro models with native IDH mutations remain scarce. Development of such models is essential to study the biology of IDH1 mutations and to develop new treatment strategies. Glioma samples were obtained directly from the operating theatre as solid resection material or CUSA aspiration, were dissociated and cells were cultured under serum-free conditions. IDH1 mutations were verified with Sanger sequencing. D2HG was measured by mass spectrometry. Cell viability was measured using an ATP-based viability assay. Drug screening was performed using an FDA-approved Oncology Drugs Set from NIH as well as with specific IDH1-mutant inhibitors. Attempts to establish a cell culture were undertaken on a total of eighty IDH1 mutant gliomas. From this series, five successful IDH1 mutant cell lines were obtained (i.e. those that remain in culture >10 passages while maintaining the IDH1-mutation). All five cell lines are 1p/19q intact, WHO grade III-IV and have an IDH1-R132H mutation. Production of the mutant IDH1 derived oncometabolite D2-HG was confirmed. Addition of IDH1-mutant inhibitor AGI-5198 resulted in differential and modest effects on 3 of the IDH1 mutant cell lines. One cell line lost its IDH1 mutation around passage 16, which indicates that at least some IDH1-mutant gliomas are no longer dependent on the mutation in vitro. In contrast, a different cell line gained a copy of IDH1-R132H without compromising its proliferation potential. Drug screening with a set of FDA-approved oncology drugs (n=107) revealed several candidates that strongly decrease cell viability at clinically-feasible concentrations. An orthotopic mouse model is in development to further assess the therapeutic potential of these agents. We have established a unique set of five native IDH-mutated cell lines, therewith providing opportunities to assess new therapeutic strategies for this subtype of malignant glioma.