Recurrent glioblastoma (GBM) or High-Grade Glioma (HGG) remains one of the most challenging neuro-oncological conditions, with limited survival benefit from conventional therapies. Emerging molecularly targeted approaches, particularly Lutetium-177–based peptide receptor radionuclide therapy (PRRT), are showing promise as innovative strategies for select patients.
Current Treatment Modalities for Recurrent GBM / HGG
1. Conventional Approaches
- Surgery (Re-resection): Considered in carefully selected patients with localized recurrence and good performance status. Benefits are modest, with median survival extension of a few months. pmc.ncbi.nlm.nih.gov
- Re-irradiation: Techniques like stereotactic radiosurgery or fractionated radiotherapy can provide local control, though toxicity risk is significant. pmc.ncbi.nlm.nih.gov
- Chemotherapy:
- Temozolomide rechallenge or lomustine (CCNU) are used, but efficacy is limited.
- Bevacizumab (anti-VEGF monoclonal antibody): FDA-approved for recurrent GBM, improves progression-free survival but not overall survival. pmc.ncbi.nlm.nih.gov
2. Targeted and Immunotherapy
- Tyrosine kinase inhibitors (TKIs): Trials with EGFR and VEGFR inhibitors have shown limited benefit.
- Immunotherapy: Checkpoint inhibitors, oncolytic viruses, and dendritic cell vaccines are under investigation, but results remain inconclusive. MDPI
- Tumor Treating Fields (TTF): Non-invasive electrical field therapy, effective in newly diagnosed GBM, but less studied in recurrence. MDPI
Lutetium-177 PRRT in GBM
Mechanism
- PRRT (Peptide Receptor Radionuclide Therapy) delivers targeted radiation via radiolabelled peptides binding to overexpressed receptors on tumor cells.
- Lutetium-177 (177-Lu): A β-emitting radionuclide with favourable half-life and tissue penetration, allowing precise tumor irradiation while sparing normal brain tissue.
Clinical Evidence
- Somatostatin receptor (SSTR) targeting: Some GBMs express SSTR2, enabling 177Lu-DOTA-TATE therapy.
- FAP-targeted PTRT: Fibroblast activation protein (FAP) is highly expressed in GBM stroma; 177Lu-FAP ligands are being explored for theranostics.
- Early-phase studies: Case reports and pilot trials suggest disease stabilization and symptomatic improvement, with acceptable toxicity profiles. pmc.ncbi.nlm.nih.gov MDPI
Advantages
- Precision delivery: Minimizes systemic toxicity compared to chemotherapy.
- Theranostic potential: PET imaging with ^68Ga-labeled analogs allows patient selection and therapy monitoring.
- Combination strategies: Potential synergy with immunotherapy or radiosensitizers.
Key Challenges
- Heterogeneous receptor expression: Not all GBMs express suitable targets for PRRT / PTRT.
- Limited clinical trial data: Most evidence is from small cohorts; randomized controlled trials are needed.
- Blood-brain barrier penetration: Remains a limiting factor for systemic delivery.
References (Selected)
- Vaz-Salgado MA, et al. Recurrent Glioblastoma: A Review of the Treatment Options. Cancers (Basel). 2023;15(17):4279. doi:10.3390/cancers15174279. pmc.ncbi.nlm.nih.gov
- Chang C, et al. Recurrent Glioblastoma—Molecular Underpinnings and Evolving Treatment Paradigms. Int J Mol Sci. 2024;25(12):6733. doi:10.3390/ijms25126733. MDPI
Conclusion
While surgery, re-irradiation, and chemotherapy remain standard fallback options, Lutetium-177 PRRT represents a promising frontier in recurrent GBM management.
Its theranostic nature, precision targeting, and emerging clinical evidence suggest it could become a valuable addition to the therapeutic armamentarium, especially when integrated into multimodal strategies.
