Gliamimic: A Longitudinal, Multimodal in Vitro Platform for Evaluating Glioblastoma Treatment Response and Relapse in Patient-derived Organoids or Spheroids

Despite decades of research, glioblastoma (GBM) remains highly treatment-resistant, underscoring the need for human-relevant in vitro models to better predict therapy response and recurrence. We developed GliaMimic, an advanced platform that exposes GBM patient-derived organoids (PDOs) or tumor cell line-based spheroids to a combined TMZ and radiotherapy regimen adapted from the standard of care Stupp regimen. By integrating multiparametric readouts (tumor size, viability, metabolic activity, cytotoxicity, apoptosis), GliaMimic enables dynamic monitoring of treatment response and relapse, an aspect rarely addressed in preclinical GBM studies. To interpret the complex data generated, we introduced two quantitative metrics: the GliaScore, assessing treatment efficacy, and the RelapseScore, evaluating post-treatment regrowth. PDOs displayed patient-specific treatment responses ranging from low to high sensitivity, whereas established cell line spheroids (U87MG, U251MG) showed minimal sensitivity, responding only to supratherapeutic TMZ doses. Notably, GliaMimic quantified different extents of tumor behaviour across GBM models, revealing patient-specific tumor progression and relapses after treatment cessation. Altogether, GliaMimic provides a robust, scalable platform for evaluating novel GBM therapies and offers a foundation for personalized treatment assessment using PDOs.