Breaking Barriers in Neuro-Oncology: A Scoping Literature Review on Invasive and Non-Invasive Techniques for Blood–Brain Barrier Disruption.

Simple Summary: Advancements in understanding the blood–brain barrier (BBB) and blood–tumor barrier (BTB) structures emphasize the need to explore functional differences influencing drug distribution to the central nervous system (CNS). Various methods for overcoming the BBB/BTB have been proposed. Osmotic BBB disruption with intra-arterial administration effectively obtains local, clinically relevant concentrations in large brain areas, with an acceptable safety profile in experienced hands. Convection-enhanced delivery allows for homogenous and safe drug delivery to the tumor but demands further technical refinement and clinical evaluation. Emerging therapies like high-intensity focused and low-intensity pulsed ultrasound show great promise in delivering large therapeutic agents to small brain areas. While laser interstitial thermal therapy is effective in ablating local brain tumors, its impact on disrupting the BBB remains inadequately understood. Similarly, tumor-treating fields aid chemotherapy in inducing cycle arrest, but the proof of their ability to disrupt the BBB/BTB has been so far limited to preclinical studies. The blood–brain barrier (BBB) poses a significant challenge to drug delivery for brain tumors, with most chemotherapeutics having limited permeability into non-malignant brain tissue and only restricted access to primary and metastatic brain cancers. Consequently, due to the drug's inability to effectively penetrate the BBB, outcomes following brain chemotherapy continue to be suboptimal. Several methods to open the BBB and obtain higher drug concentrations in tumors have been proposed, with the selection of the optimal method depending on the size of the targeted tumor volume, the chosen therapeutic agent, and individual patient characteristics. Herein, we aim to comprehensively describe osmotic disruption with intra-arterial drug administration, intrathecal/intraventricular administration, laser interstitial thermal therapy, convection-enhanced delivery, and ultrasound methods, including high-intensity focused and low-intensity ultrasound as well as tumor-treating fields. We explain the scientific concept behind each method, preclinical/clinical research, advantages and disadvantages, indications, and potential avenues for improvement. Given that each method has its limitations, it is unlikely that the future of BBB disruption will rely on a single method but rather on a synergistic effect of a combined approach. Disruption of the BBB with osmotic infusion or high-intensity focused ultrasound, followed by the intra-arterial delivery of drugs, is a promising approach. Real-time monitoring of drug delivery will be necessary for optimal results. [ABSTRACT FROM AUTHOR]