Radar Technology Finds New Target

February 1, 2011

Medifocus, Inc., (Columbia, MD), formerly Celsion Canada Limited, has developed a device known as the APA-1000™ that uses an adaptive phased array (APA) radar technique, originally developed by the Massachusetts Institute of Technology (MIT) for the Strategic Defense Initiative Organization (SDIO), to safely heat breast tumors.

Working in the 1980s at MIT, Alan J. Fenn, Ph.D., originally developed the APA system to deploy from space-based radar platforms to locate airborne weapons such as cruise missiles as part of the Strategic Defense Initiative (SDI). The algorithms were designed to overcome enemy jamming by removing the electronic noise from the radiation signals coming back to the radar.

A precursor device to the APA-1000, named the Microfocus 1000™, received a pre-market approval from the Food and Drug Administration in 1997. Since that time, Medifocus has progressed through the clinical trial process to demonstrate the efficacy of its heating regimen.

How it Works:

APA uses algorithms that are similar to those used for adaptive optics, which work to oppose wavelengths of a certain size in order to clarify images.

The very same APA techniques that were developed by Dr. Fenn and patented by MIT for cancer treatment are now being applied by Medifocus in human clinical trials for patients with breast cancer. In this application, the APA technology allows the microwave energy to be accurately focused on a breast-cancer tumor and cancel out, or “null,” the heating effect in nearby healthy tissue. This specific ability to target a tumor while sparing normal tissue has been high on the wish list of every oncologist for decades. Many methods have been used experimentally to physically destroy tumors, such as radio-frequency waves, laser photocoagulation, focused ultrasound, and cryotherapy (freezing). Microwaves also strongly excite water molecules, which are more plentiful in breast tumors compared to surrounding normal tissue. Combined with the focusing effect of APA algorithms, this treatment technique allows an even greater concentration of energy at the tumor site, while nearby, less water-laden healthy tissue remains unaffected.

The APA-1000 uses two external microwave heating antennas that are external to the breast and a small antenna that makes contact with the tumor through a minor incision in the skin; the procedure is performed under local anesthesia. The catheter placement of the antenna is minimally invasive, allowing patients to leave the treatment session with only a small bandage. A proprietary feedback tracking mechanism is used to focus microwave energy at the center of the tumor, while a computer controls the amount of energy and monitors the temperature.

For obvious reasons, many patients would prefer breast-conserving surgery (BCS, also known as lumpectomy) over mastectomy. But to do this, the patient’s breast tumor must measure a certain size and present “clean” tumor margins. In Phase II trials with the APA-1000 and anthracycline-based chemotherapy, almost 80 percent of all breast tumors treated had a tumor volume reduction of 80 percent or more, compared with only 20 percent for the tumors treated by chemotherapy alone. These results with the APA-1000 suggest that the device alone can reduce evidence of cancer in the tumor margins, which makes BCS, as opposed to mastectomy, more of a possibility.

And statistics show that, when appropriately chosen, BCS can be just as effective as mastectomy.

Those study results imply that women who choose BCS over mastectomy are not making a frivolous cosmetic decision, but rather an important choice between therapies that have very different side-effect profiles. Mastectomy has numerous downsides aside from its obvious psychological effect, including fluid accumulation in the arm and the development of scar tissue that can contract and limit movement over time. These side effects typically do not occur with BCS.

Where it Stands

In the United States, the APA-1000 has now been tested through four separate Phase I and Phase II clinical trials, and has demonstrated that it can be safely used. The next step will be Phase III clinical trials to demonstrate APA-1000’s ability to render breast tumors more sensitive to chemotherapy, enabling some patients to be possibly eligible for breast-conserving surgery.

Medifocus recently received the green light to proceed with these pivotal Phase III trials in Canada for patients with large breast tumors. Medifocus is working with Ville Marie Medical Center in Montreal, Quebec to start the Canadian trial.

The company also has received Food and Drug Administration (FDA) approval for the United States arm of the trials. The principal investigator in the United States is William C. Dooley, M.D., at the University of Oklahoma. A total of 238 patients will be entered into the randomized study.

More Information

For more information on the APA-1000™, visit http://info.hotims.com/34451-522  . (Source: Joan Zimmermann/NTTC; MDA TechUpdate, Missile Defense Agency, National Technology Transfer Center Washington Operations).

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