[1S04a] 14. Chemical Biotechnology - Part 2

2:00 PM - 2:30 PM JST(5:00 AM - 5:30 AM UTC)

[1Chemi-07-KL] Reducing tumor heterogeneity with TTFields prevents glioblastoma recurrence by concurrently inhibiting the membrane form of the CLIC1 protein

○Michele Mazzanti¹, Francesca Cianci¹, Elisa Meraviglia¹, Guido Rey¹, Antonio Maria Polito¹, Sara Torabi¹, Stefania Castiglione¹, Chiara Agnese Mercurio¹, Ditmar Krex⁵, federica Barbieri², Tullio Florio^2,3, Martin Gabay⁴, Tatiana Vorobyov⁴, Kerem Wainer Katsir⁴, Yaara Porat⁴, Roni Blat⁴, Ori Braten⁴, Itai Tzchori⁴ (1. Department Bioscience, University of Milano (Italy), 2. Department of Internal Medicine, University of Genova (Italy), 3. IRCS Ospedale Policlinico San Martino (Italy), 4. Novocure GmbH (Switzerland), 5. Technische Universität Dresden (Germany))

Keywords:

Glioblastoma,Cancer heterogeneity,Metabolic reprogramming,Treatment resistance,Drug repurposing

Glioblastoma (GB) is the most aggressive primary brain tumor, and current treatments rarely prevent recurrence. Tumor Treating Fields (TTFields) are a novel, noninvasive therapy that can delay progression but fail to prevent relapse in most patients. The marked intra- and inter-tumoral heterogeneity of GB further complicates therapeutic strategies. Metformin, an antidiabetic drug, inhibits transmembrane chloride intracellular channel 1 (tmCLIC1), a protein broadly expressed in GB stem cells that sustains tumorigenicity and metabolic reprogramming. Investigating tmCLIC1's role in resistance to TTFields may reveal strategies to improve therapeutic efficacy.
Patient-derived GB cultures representing distinct molecular subtypes were exposed to continuous TTFields for 2 weeks to model postsurgical therapy. Functional assays assessed tmCLIC1 activity, stemness markers, and metabolic adaptations. Transcriptomic analyses were performed on paired patient resections, including cases treated with TTFields between surgeries. The combined effect of TTFields and metformin was evaluated in vitro and in mouse models.
All GB cultures resumed proliferation after prolonged exposure to TTFields, regardless of initial sensitivity. Resistant cells converged on a mesenchymal-like phenotype. Transcriptomic profiling revealed upregulation of myelination-associated pathways characteristic of mesenchymal GB, offering limited therapeutic opportunities. tmCLIC1 was consistently overexpressed in resistant cells. Combined treatment with TTFields and metformin produced a synergistic effect, significantly impairing tumor growth in vitro and in vivo.
Despite GB heterogeneity, resistance to TTFields converges on a mesenchymal-like phenotype characterized by increased tmCLIC1 expression. Targeting tmCLIC1 with metformin in combination with TTFields is a promising strategy to enhance therapeutic efficacy and limit tumor recurrence.