Radar Anti-Jamming Technology Helps Shoot Down Cancer

February 1, 2007

Phased-array techniques are used to improve radar and communications systems by simultaneously nullifying and amplifying electromagnetic waves. With a focused heating regimen based on an adaptive phased array (APA) technique, a targeted microwave therapy is being tested to fight breast cancer.

A technology funded by the Missile Defense Agency (MDA) at Lincoln Laboratory nearly 20 years ago is being used in a new clinical trial. During the latter years of the Cold War, Dr. Alan Fenn of the Massachusetts Institute of Technology (MIT) developed an adaptive phased-array antenna for nulling and focusing radar for missile detection under the Strategic Defense Initiative Organization (SDIO). The same technique was found to be useful in directing heat to deep-seated tumors, while reducing "hot spots" in surrounding healthy tissue.

Dr. Augustine Cheung, founder of Celsion Corporation, a medical device company in Columbia, MD, had been interested in using heat to treat disease, and acquired an exclusive license to Dr. Fenn's technology. He incorporated it into Celsion's MicroFocus 1000™. Over the years, the company has released a line of thermotherapy platforms to treat benign prostatic hyperplasia (BPH) and liver cancer, using radio-frequency (RF) waves to provide heat. Celsion moved towards RF-based thermal therapy with liposome-encapsulated chemotherapy drugs, and the APA technique simmered on the back burner. In studies conducted from 1999 to 2004, Dr. Fenn continued tests of the APA-based MicroFocus 1000 device in breast cancer patients as a neoadjuvant treatment prior to breast surgery.

How it Works

Various approaches to tumor destruction have been studied, including focused ultrasound, cryoablation (freezing), and laser photocoagulation. Heat applied in the form of radio waves and microwaves also has been used.

Microwaving is a form of electromagnetic radiation, so microwaves focused on tumors in the breast result in localized heating of the cancer cells. Microwave treatment can result in tumor necrosis or cell death as the heat enhances the effects of the chemotherapy drug, resulting in the tumor shrinking in a matter of weeks. Focused microwaves also have the ability to treat microscopic cancer tumors that cannot be seen. Celsion's minimally invasive, non-toxic, focused microwave technology targets and treats tumors over 1 cm in diameter, unlike radio frequency devices or laser-induced thermotherapy.

A minimally invasive disposable catheter sensor is inserted into the breast under ultrasound guidance to provide feedback signals for microwave and temperature measurement. The breast is immobilized by compression, which reduces blood flow and increases the effectiveness of the heat treatment. Microwave energy then is applied to the breast with two applicators. A proprietary feedback tracking mechanism ensures the energy is focused on the center of the tumor, while a computer algorithm controls the amount of energy applied to the tumor, and monitors the temperature to ensure optimum effectiveness.

Two advantages of APA focusing are its ability to deliver heat into tumor sites deep in the body, and the fact that microwave energy preferentially heats tumor cells, which have comparatively higher water content than surrounding healthy tissue. The placement of the antenna is minimally invasive, allowing patients to leave the treatment with only a small bandage.

Eventually, the company hopes that APA can be applied remotely, without the need to insert any needle into the tumor. Remote application would be helpful in focusing energy on chest wall tumors, which are more difficult to treat than those that occur on the periphery of the breast.

Where it Stands

Researchers have demonstrated in 35 breast cancer patients the safety of the method for killing tumors by the use of heat alone. In one study, 10 patients scheduled for mastectomies received the heat-alone APA focusing treatment prior to surgery, and eight of 10 patients had a tumor response. All of the patients were required to have a mastectomy regardless of any tumor response. In another study, 25 patients with early-stage breast cancer scheduled for lumpectomies received the heat-alone focusing treatment, and the heat dose for 100% tumor kill was established. All of the patients had lumpectomies and only one had any residual cancer cells after surgery.

Two more studies of the APA focusing treatment in more than 40 additional patients with early-stage and advanced breast cancer have been explored and the results are awaiting publication. The outcomes of these initial trials in more than 75 patients are encouraging, and clinicians have decided to add a new component to the APA treatment, again prior to surgery in a clinical trial for patients with advanced breast cancer.

Early last year, Dr. Cheung devoted his full-time efforts to the development of APA technology as a thermotherapy platform for breast cancer treatment. Currently, he is preparing a round of clinical studies that combine APAbased tumor heating with intravenous infusion of Adriamycin® (doxorubicin) and other drugs. The idea is that the drugs will be "enhanced" by heating, possibly speeding up reaction times, and resulting in a higher response rate at the tumor site. Simultaneously, the ordinary systemic action of the drugs will target any circulating tumor cells or potential micrometastases elsewhere in the body.

More Information

For more information on Celsion Canada, visit http://info.hotims.com/10962-843  .

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