Magnetic hyperthermia therapy for the treatment of glioblastoma: a review of the therapy's history, efficacy and application in humans

Abstract

Hyperthermia therapy (HT) is the exposure of a region of the body to elevated temperatures to achieve a therapeutic effect. HT anticancer properties and its potential as a cancer treatment have been studied for decades. Techniques used to achieve a localised hyperthermic effect include radiofrequency, ultrasound, microwave, laser and magnetic nanoparticles (MNPs). The use of MNPs for therapeutic hyperthermia generation is known as magnetic hyperthermia therapy (MHT) and was first attempted as a cancer therapy in 1957. However, despite more recent advancements, MHT has still not become part of the standard of care for cancer treatment. Certain challenges, such as accurate thermometry within the tumour mass and precise tumour heating, preclude its widespread application as a treatment modality for cancer. MHT is especially attractive for the treatment of glioblastoma (GBM), the most common and aggressive primary brain cancer in adults, which has no cure. In this review, the application of MHT as a therapeutic modality for GBM will be discussed. Its therapeutic efficacy, technical details, and major experimental and clinical findings will be reviewed and analysed. Finally, current limitations, areas of improvement, and future directions will be discussed in depth.

Keywords: Magnetic hyperthermia therapy; alternating magnetic field; convection enhanced delivery; glioblastoma; magnetic nanoparticles.

Figure 1

MHT in a patient with a malignant brain tumour. (A) Following the delivery of MNPs to the tumour site, the patient’s head is positioned within an AMF generator. (B) Heat is produced (circles) by MNPs (small spheres) mainly through magnetic hysteresis losses. (C) The localised delivery of MNPs (small spheres) via convection-enhanced delivery (CED) results in a high concentration of MNPs in and around the tumour site. (D) The uptake of MNPs (small spheres) by tumour cells (large structures with a dark center) and macrophages (not shown) results in an enhanced cellular response to heat. Adapted from [46].