Radio Frequency Ablation (RFA) & High-intensity Focused Ultrasound (HIFU)
Dieter Haemmerich, PhD, of the Developmental Cancer Therapeutics Program, is leading two NIH-funded projects that focus on destroying solid tumors with heat created by radiofrequency electric current and by high-intensity focused ultrasound (HIFU).
Radio Frequency Ablation (RFA)
Radiofrequency ablation (RFA) is a promising minimally invasive, heat-based method used to destroy cancer of the liver, kidney, bone, and lung. Using images as guidance, an electrode is inserted into the tumor, and radiofrequency current is applied, resulting in tissue-heating within a few cm around the electrode. Unlike conventional radiation or chemotherapy, RFA can be repeated as often as necessary.
The tumor is destroyed once it reaches temperatures above 50 ºC. Since RFA is minimally invasive and localized, morbity risk is lower and patients recover faster. Historically, commercial RFA devices operate in the frequency range of 450 – 500 kHz.
In this project, Dr. Haemmerich is seeking to confirm previous findings of his that RFA at lower frequencies (~10 kHz) may preferentially heat tumor tissue while sparing surrounding healthy tissue.
High-Intensity Focused Ultrasound (HIFU)-Mediated Targeted Drug Delivery
High-intensity focused ultrasound (HIFU) is a precise non-invasive procedure using pressure waves to generate heat to destroy pathogenic tissue rapidly.
Working with researchers at the National Cancer Institute, Dr. Haemmerich is exploring combining HIFU with special drug delivery vehicles, called low-temperature-sensitive liposomes (LTSL), to more effectively deliver chemotherapy to tumors. These LTSL circulate in the blood stream and release contents (i.e. chemotherapy) above ~40 ºC, allowing localized chemotherapy delivery to cells in tissue regions (e.g. tumor) that are heated by HIFU.
Since drugs and radiation are often ineffective in central regions of large tumors that are poorly perfused, HIFU could be employed to directly destroy these central regions while drugs released from LTSL kill cancer cells in surrounding regions.
This project’s goals are to determine at what temperature and length of heating drug delivery is maximized.