November 23, 2010 (New York City) — Irreversible electroporation (IRE) holds promise for the treatment of hepatocellar carcinoma (HCC) and other soft tissue tumors.
Although the technique, called NanoKnife (Angiodynamics), is not ready for prime time for these indications, more than 200 patients worldwide have had tumors successfully treated with the new technique, announced Laura Crocetti, MD, from the University of Pisa, Italy, one of the investigators in an ongoing European multicenter phase 3 trial to study the technique in patients with early HCC. Dr. Crocetti spoke about IRE here at the 37th Annual VEITH Symposium.
Unlike radiofrequency ablation (RFA) or microwave techniques, the NanoKnife does not use thermal energy to kill tumor cells. Instead, it uses electricity to break the cell membrane, Dr. Crocetti explained.
"I believe IRE is very promising, but we have to define its role vis-à-vis other treatment options. At present, the technique is cumbersome, requiring 3 electrodes and general anesthesia with muscle blockade. It needs to be refined," she stated.
Reversible electroporation, a technique that has been available for some time, uses short-pulse, high-voltage direct current to increase cell membrane permeability by disrupting its integrity, allowing transportation of drugs or gene therapy into the cell. IRE uses very high voltage (>1500 volts) to induce irreversible damage to cell membrane integrity, producing cell death, Dr. Crocetti explained.
Animal studies showed that the area of ablation can be predicted when using IRE, and the procedure can be planned precisely, thus preserving adjacent structures, she said. It is faster than RFA and microwave techniques, taking about 5 minutes for the entire procedure. The placement of the needles is done under ultrasonography or computed tomography imaging. "The machine predicts the tumor volume and tells you the amount of voltage you need," she said.
The phase 3 trial plans to enroll 25 patients with early-stage HCC at 7 European centers. Patients can have up to 3 tumors that are up to 3 cm in diameter each and cannot be candidates for resection or transplantation. The primary endpoint is tumor response; secondary endpoints include safety, local recurrence, and overall survival.
"This technique is promising. We have shown that tumors can be treated safety, and we can treat tumors that are in sites that are not ideal for RFA and microwave ablation," Dr. Crocetti told Medscape Medical News.
Commenting on Dr. Crocetti's presentation, James Caridi, MD, said, "This was a great presentation. The technique is promising and does not affect adjacent structures, including blood vessels." Dr. Caridi is chief of vascular surgery and interventional radiology at the University of Florida in Gainesville. "There is no collateral damage of the nerves, blood vessels, bladder, or bowel. Other modalities leave a scar, but there is no scarring with IRE. Scars can interfere with imaging in the future," he explained.
Dr. Caridi has used IRE in 15 patients with tumor types that include primary HCC, hepatic metastases, and kidney tumors and is enthusiastic about the technique.
"We use this on patients who have exhausted all other treatment options. We place the probes [in the tumor] and destroy the tissue. I usually have to write a letter to the insurance company because it is not reimbursable by insurance or Medicare," Dr. Caridi explained.
Although IRE effectively kills tumors, it is unknown whether this translates to reduced recurrence or improved survival. An outcomes study is in the planning stages at Jackson Memorial Hospital in Miami, Florida, to look at outcomes with IRE. Other investigators are planning to start a registry of patients with tumors treated with IRE, he said.
He agreed with Dr. Crocetti that refinements are needed to make the NanoKnife more "user-friendly." This would include developing a single deployment probe that opens like an umbrella to treat the tumor volume, instead of the 3 probes that are presently used.
The phase 3 trial is supported by Angiodynamics. Dr. Crocetti and Dr. Caridi have disclosed no relevant financial relationships.
37th Annual VEITH Symposium. Presented November 19, 2010.
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Cite this: Electroporation Effective in Hepatocellular Carcinoma - Medscape - Nov 23, 2010.