New Imaging Agent Being Tested for Early Detection of Alzheimer’s

A new imaging agent currently in Phase III clinical trials could soon make it possible for more radiologists to see beta-amyloid - the brain plaque associated with suspected Alzheimer’s disease - through PET scans.

According to David Wolk, MD, University of Pittsburgh neurology professor, flutemetamol, a tracer molecule associated with the isotope Fluorin-18, brings the same benefit to real-time patient care that Pittsburgh B-Compound (PiB) can only bring to neurological investigations.

“Because of the PiB compound’s 20-minute half-life, it’s really only played an active role in research. It degrades so quickly that it’s not practical to use with patients in the real world - only tertiary care centers have the machinery to make PiB onsite,” said Wolk, who presented his research on flutemetamol in living patients at the International Conference on Alzheimer’s Disease in Paris last week.

“With a nearly two-hour half-life, you can have flutemetamol manufactured elsewhere and delivered to you for medical scans.”

As a tracer, flutemetamol is almost identical to PiB, attaching itself to and highlighting beta-amyloid present in the brain. This similarity would mean there would be no changes in how you use your imaging agents or your PET equipment. You would have almost no learning curve, Wolk said.

In a commentary published in the July 11 Archives of Neurology and linked to Wolk’s study, William Jagust, MD, from the University of California-Berkeley Helen Wills Neuroscience Institute and School of Public Health, said flutemetamol does have the potential to positively impact patient care.

“The recent advent of longer-lived radiopharmaceuticals labeled with fluorine 18 have made [the technology to detect beta-amyloid] more available and commercially viable,” Jagust wrote.

Switching to flutemetamol won’t change the therapies given to patients who have suspected Alzheimer’s, but it could help identify which people will likely develop the disease earlier on, Wolk said, giving providers a head start on treating the symptoms of the disease. From a research perspective, earlier diagnoses will give scientists greater opportunities to study and understand the progression of the disease. Those investigations could, one day, lead to treatments that address disease itself.

In addition to flutemetamol, which is being tested by GE, there are two other tracers linked to Fluorin-18 that are also in Phase III trials. According to Jonathan Allis, MI PET Segment Leader at GE, the company hopes to complete its trial by the end of this year and submit its findings to the appropriate regulatory bodies in early 2012.

The company is also creating a standardized training platform to ensure imaging with flutemetamol is done correctly despite the tracer having a greater clinical impact than a technical one, he said.

“This is less of a technical issue and more of a medical one because doctors are still learning what it really means to have increased beta-amyloid signals in the brain,” Allis said. “We don’t know if having increased beat-amyloid when you’re younger means something different than when you’re older, but being able to identify the plaque earlier can help answer that question.”