2MO - Integrating regorafenib sensitivity and functional precision medicine for second-line therapy in recurrent glioblastoma

Background

Glioblastoma (GBM) is the most aggressive malignant tumor of the central nervous system, characterized by poor prognosis despite standard treatments like maximal resection, temozolomide (TMZ) chemotherapy, and radiotherapy. Recent advances, including the phase II REGOMA trial, highlighted regorafenib (REGO) as a promising second-line treatment. In this study, we integrated findings from two investigations: (1) the molecular mechanisms underlying REGO sensitivity in recurrent GBM (rGBM) and (2) the correlation between ex vivo drug sensitivity testing on patient-derived organoids and clinical outcomes following second-line chemotherapy.

Methods

Patient-derived 3D glioblastoma organoids (GBM-EXPs) were established from 26 samples (18 patients), including primary, recurrent, and peripheral tumors. Organoids were treated with TMZ, or REGO, and drug response was evaluated using NAD(P)H Fluorescence Lifetime Imaging (FLIM). Whole-exome and transcriptome analyses were performed on selected samples. Additionally, clinical outcomes from a prospective study on 16 patients were correlated with in vitro drug response assays.

Results

Among the 26 samples, 35% were sensitive to TMZ and 77% to REGO. REGO-sensitive tumors exhibited distinct mutational and transcriptional profiles, including alterations in OR13C5 and MLLT3, and pathways such as Rho GTPase and NOTCH signaling. In the clinical study, rGBM-EXPs sensitive to REGO showed significantly longer progression-free survival (PFS2, 7.5 vs. 3.6 months; p=0.04). Prospective ex vivo testing influenced treatment decisions, yielding longer median PFS2 (7.4 vs. 4.6 months; p=0.08) and OS2 (not reached vs. 6.3 months; p=0.03).

Conclusions

This study demonstrates that REGO is more effective than TMZ in treating recurrent GBM, with sensitivity strongly reflected in molecular profiles. Ex vivo drug response testing using NADH-FLIM is a promising approach to predict second-line therapy efficacy and guide personalized treatment strategies. These findings underscore the potential of functional precision medicine in improving outcomes for GBM patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.