Interstitial Hyperthermia With Intra-arterial Injection of Adriamycin for Malignant Glioma

Strategies for Improved Intra-arterial Treatments Targeting Brain Tumors: a Systematic Review

Conventional treatments for brain tumors relying on surgery, radiation, and systemic chemotherapy are often associated with high recurrence and poor prognosis. In recent decades, intra-arterial administration of anti-cancer drugs has been considered a suitable alternative drug delivery route to intravenous and oral administration. Intra-arterial administration is believed to offer increasing drug responses by primary and metastatic brain tumors, and to be associated with better median overall survival. By directly injecting therapeutic agents into carotid or vertebral artery, intra-arterial administration rapidly increases intra-tumoral drug concentration but lowers systemic exposure. However, unexpected vascular or neural toxicity has questioned the therapeutic safety of intra-arterial drug administration and limits its widespread clinical application. Therefore, improving targeting and accuracy of intra-arterial administration has become a major research focus. This systematic review categorizes strategies for optimizing intra-arterial administration into five categories: (1) transient blood-brain barrier (BBB)/blood-tumor barrier (BTB) disruption, (2) regional cerebral hypoperfusion for peritumoral hemodynamic changes, (3) superselective endovascular intervention, (4) high-resolution imaging techniques, and (5) others such as cell and gene therapy. We summarize and discuss both preclinical and clinical research, focusing on advantages and disadvantages of different treatment strategies for a variety of cerebral tumor types.

Thermal Therapy Approaches for Treatment of Brain Tumors in Animals and Humans

Primary brain tumors are often aggressive, with short survival from time of diagnosis even with standard of care therapies such as surgery, chemotherapy, and radiation therapy. Thermal therapies have been extensively investigated as both primary and adjuvant therapy. Although thermal therapies are not yet widely used clinically, there have been several promising approaches demonstrated in both animals and humans. This review presents thermal therapy approaches in animal and human studies, including both hyperthermia (temperatures ~42°C-45°C) and thermal ablation (temperatures > 50°C). Hyperthermia is primarily used as adjuvant to chemotherapy and radiotherapy, and is the most widely studied radiation sensitizer where enhanced efficacy has been shown in human patients with brain cancer. Hyperthermia has additional beneficial effects such as immunogenic effects, and opening of the bloodbrain barrier to potentially enhance drug delivery, for example in combination with nanoparticle drug delivery systems. Thermal ablation uses high temperatures for direct local tumor destruction, and it found its way into clinical use as laser interstitial thermal therapy (LITT). This review presents various hyperthermia and ablation approaches, including a review of different devices and methods that have been used for thermal therapies, such as radiofrequency/microwaves, laser, high-intensity focused ultrasound, and magnetic nanoparticles. Current research efforts include the combination of advanced thermal therapy devices, such as focused ultrasound with radiation, as well as the use of thermal therapies to enhance chemotherapy delivery across the blood-brain barrier.

Alternating magnetic field-induced hyperthermia increases iron oxide nanoparticle cell association/uptake and flux in blood-brain barrier models

PURPOSE

Superparamagnetic iron oxide nanoparticles (IONPs) are being investigated for brain cancer therapy because alternating magnetic field (AMF) activates them to produce hyperthermia. For central nervous system applications, brain entry of diagnostic and therapeutic agents is usually essential. We hypothesized that AMF-induced hyperthermia significantly increases IONP blood-brain barrier (BBB) association/uptake and flux.

METHODS

Cross-linked nanoassemblies loaded with IONPs (CNA-IONPs) and conventional citrate-coated IONPs (citrate-IONPs) were synthesized and characterized in house. CNA-IONP and citrate-IONP BBB cell association/uptake and flux were studied using two BBB Transwell(®) models (bEnd.3 and MDCKII cells) after conventional and AMF-induced hyperthermia exposure.

RESULTS

AMF-induced hyperthermia for 0.5 h did not alter CNA-IONP size but accelerated citrate-IONP agglomeration. AMF-induced hyperthermia for 0.5 h enhanced CNA-IONP and citrate-IONP BBB cell association/uptake. It also enhanced the flux of CNA-IONPs across the two in vitro BBB models compared to conventional hyperthermia and normothermia, in the absence of cell death. Citrate-IONP flux was not observed under these conditions. AMF-induced hyperthermia also significantly enhanced paracellular pathway flux. The mechanism appears to involve more than the increased temperature surrounding the CNA-IONPs.

CONCLUSIONS

Hyperthermia induced by AMF activation of CNA-IONPs has potential to increase the BBB permeability of therapeutics for the diagnosis and therapy of various brain diseases.