Hyperthermia

Elevating tissue temperature to a mild 42°C (107°F) and maintaining for several minutes can increase blood flow and drug absorption in the targeted region without causing permanent damage1.

Using the body’s response to this localized mild hyperthermia, drug delivery and uptake can be enhanced2. Additionally, more oxygen is delivered to hyperthermic targets, enhancing their metabolic activity and sensitivity to drugs. This method has been used in clinical settings to enhance the delivery and efficacy of drugs in targeted areas with restricted blood flow, especially tumors.

Focused ultrasound is an optimal technology for inducing hyperthermia because of its precise focus and its ability to deposit energy in various shapes and sizes. Tissue temperature can be monitored in real time using magnetic resonance imaging, ultrasound imaging or interstitial thermocouples, which allows for the accurate control of the treatment3,4. The effects induced by local hyperthermia are temporary and precise, and hold potential to make focused ultrasound an excellent complement to drug therapy2,5,6. Because of focused ultrasound’s ability to penetrate deep into the body, there are numerous and wide ranging potential clinical uses for hyperthermia. Many drugs would benefit from the enhanced delivery and efficacy, and mild hyperthermia has even been shown to induce an immune response against some tumors7.

References

[1] Thanou M, Gedroyc W. MRI-Guided Focused Ultrasound as a New Method of Drug Delivery. J. Drug Deliv. 2013;2013:e616197.

[2] S. Wang, V. Zderic, and V. Frenkel, “Extracorporeal, low-energy focused ultrasound for noninvasive and nondestructive targeted hyperthermia.,” Future Oncol., vol. 6, no. 9, pp. 1497–1511, Sep. 2010. 

[3] Hurwitz MD, Kaplan ID, Hansen JL, Prokopios-Davos S, Topulos GP, Wishnow K, et al. Hyperthermia combined with radiation in treatment of locally advanced prostate cancer is associated with a favourable toxicity profile. Int. J. Hyperth. Off. J. Eur. Soc. Hyperthermic Oncol. North Am. Hyperth. Group. 2005;21:649–56.

[4] Arthur RM, Straube WL, Trobaugh JW, Moros EG. Non-invasive estimation of hyperthermia temperatures with ultrasound. Int. J. Hyperth. Off. J. Eur. Soc. Hyperthermic Oncol. North Am. Hyperth. Group. 2005;21:589–600.

[5] J. P. May and S.-D. Li, “Hyperthermia-induced drug targeting.,” Expert Opin. drug Deliv., vol. 10, no. 4, pp. 511–527, Apr. 2013. 

[6] S. Wang, V. Frenkel, and V. Zderic, “Optimization of pulsed focused ultrasound exposures for hyperthermia applications.,” J. Acoust. Soc. Am., vol. 130, no. 1, pp. 599–609, Jul. 2011. 

[7] Peer AJ, Grimm MJ, Zynda ER, Repasky EA. Diverse immune mechanisms may contribute to the survival benefit seen in cancer patients receiving hyperthermia. Immunol. Res. 2009;46:137–54


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