· RapidArc Reduces Treatment Times for Cancer Patients
· FDA: PET Agents Could Help Predict Alzheimer’s Disease

RapidArc Reduces Treatment Times for Cancer Patients

When Sabin Robbins, 75, was recently diagnosed with prostate cancer, he learned that he was a candidate for new radiotherapy technology that would reduce his daily treatment times. His physicians at Bethesda Comprehensive Cancer Center, Boynton Beach, Fla, told him about the facility’s RapidArc system, a volumetric modulated arc therapy from Varian Medical Systems, Palo Alto, Calif, designed to deliver treatment two to eight times faster than traditional methods, such as intensity-modulated radiation therapy (IMRT).

RapidArc is a volumetric modulated arc therapy designed to deliver treatment two to eight times faster than traditional methods.

For 8 1/2 weeks, Robbins received daily therapy from a RapidArc-equipped linear accelerator, which delivers treatments in one 360? gantry rotation. Once he was positioned for treatment and the image-guidance technology pinpointed the tumor’s location, each treatment took about 70 seconds to complete.

“I have been pleasantly surprised at the quickness of the treatments,” Robbins said.

During treatment, RapidArc uses a treatment-planning algorithm that simultaneously changes the rotation speed of the gantry, the delivery dose rate, and the shape of the treatment aperture using the movement of multileaf collimator leaves.

“RapidArc allows us to more closely shape the treatment beam to the tumor,” said Bruce Greene, MD, director of radiation oncology at Bethesda. “Compared with conventional IMRT treatment plans, we are finding that normal tissue sparing is noticeably better with RapidArc. Because of this accuracy, we expect to improve clinical outcomes and reduce unwanted side effects.”

Greene also notes a correlation between the treatment accuracy and the speed of the RapidArc treatment. “Normal physiology will cause a tumor to move slightly, even within the 7 to 10 minutes needed to complete a conventional IMRT treatment,” Greene said. “What we’re seeing with RapidArc is that treatments are completed fast enough to reduce the range of tumor movement during the treatment.”

To date, RapidArc radiotherapy technology has been used to treat prostate, head and neck, lung, brain, spine, bone, gynecological, and soft-tissue cancers.

FDA: PET Agents Could Help Predict Alzheimer’s Disease

Using imaging agents to determine the presence of amyloid plaque in the brain could help physicians predict the likelihood of Alzheimer’s disease in patients, according to the FDA Peripheral and CNS Advisory Committee. Although it is unclear what role amyloid plaque plays in the development of the disease, many researchers believe there is a connection between the presence of amyloid in the brain and the onset of Alzheimer’s, according to a recent article in The Wall Street Journal.

Representatives from Avid Radiopharmaceuticals, Bayer Healthcare Pharmaceuticals, and GE Healthcare met with the FDA advisory committee to discuss development plans for how the companies will seek approval for imaging amyloid in the brain.

When used with PET imaging, the imaging agents would be able to show whether amyloid plaque was present in a living patient’s brain. “If your scan does not show any evidence of amyloid in the brain, then you have an extremely low likelihood of having Alzheimer’s disease, because Alzheimer’s disease requires the presence of amyloid plaque in the brain,” says Alan P. Carpenter, Jr, PhD, JD, vice president of business development and legal and regulatory affairs for Avid Radiopharmaceuticals, Philadelphia. “That’s usually determined at autopsy, but with this imaging technology, now we can start to see these things in vivo.”

Avid will be working with the FDA to finalize clinical trials, and the company also plans to start Phase III trials of its amyloid imaging compound, 18F-AV-45 (AV-45), in the first quarter of 2009.

“With imaging biomarkers for amyloid in the brain, we hope that this test will be a useful means of selecting people who should be enrolled in studies of new therapies,” Carpenter says. These tests could also potentially help determine who should be treated most aggressively with amyloid-lowering therapies that are currently under development, he adds.

“We’re working closely with pharma companies now, and we hope that one or more of these new treatments that are being investigated will be approved in the next 5 years,” Carpenter says.

While there is no known cure for Alzheimer’s disease, being able to detect amyloid plaque in the brain could help prepare individuals and families. “It’s important for families and people who have a concern about memory impairment to have more certainty about their future course,” Carpenter says. “And it’s useful for people to have quality time to make plans appropriately based upon their own circumstances.”