DDDR-22. PREDICTING AND TARGETING CLONALLY EXPANDING, TMZ-RESISTANT TUMOR CELLS IN GLIOBLASTOMA

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2023-11, Vol.25 (Supplement_5), p.v110-v110
• Main Authors: Ullrich, Vivien, Ertmer, Sarah, Berger, Pia, Langer, Sarah, Baginska, Anna, Gull, Hanah, Dorsch, Madeleine, Cima, Igor, Dobersalske, Celia, Kebir, Sied, Glas, Martin, Rauschenbach, Laurèl, Sure, Ulrich, Roesch, Alexander, Gruener, Barbara M, Scheffler, Björn
• Format: Article
• Language: English
• Subjects: Drug Discovery, Drug Resistance
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noad179.0416

Abstract Emerging evidence supports the notion that phenotypic plasticity contributes to disease progression and drug resistance in malignant glioma. We have recently described a rare population of ALDH1A1+ tumor cells in newly diagnosed, treatment-naive glioblastoma that can adapt to the exposure of the standard chemotherapeutic temozolomide (TMZ). Their subclonal growth leads to AKT-driven, TMZ-resistant cellular hierarchies. Accumulation of ALDH1A1+/pAKT+ cells can therefore be noted subsequent to TMZ in patient relapse tissue and in PDX models of disease. We have also shown that this series of events requires a sequential targeting approach where these subclones are allowed to enrich under TMZ and, only in a second step, are treated with AKT inhibitors. This “enrich and kill” strategy doubles the TMZ-based survival benefit in preclinical PDX models (Kebir et al., Clin Cancer Res 2023). Here, we took advantage of short-term expanded patient-derived cell cultures, which allow the study of early stages of this type of adaptive plasticity in controlled conditions. Specifically, we characterized the human lysine-specific demethylase 5B (KDM5B) as a prospective indicator for subclonal expansion in rare cells under first-time exposure to TMZ. We used genetic reporters, pharmacological interference, CHIP-seq analysis and cellular barcoding to investigate the dynamics of KDM5B expression and the related intracellular cross-signaling. We monitored patient cell samples over prolonged periods of time, and we found that KDM5Bhigh treatment-naive glioblastoma cells preferentially contribute to the dynamics of ALDH1A1 subclones and drug resistance under the influence of TMZ. These findings may lay ground for the development of biomarker-assisted clinical trials. This work is supported by DFG/GRC-CRU337/2 (proj#405344257).