The big FDA news so far this year in molecular neuroimaging was the approval of Piramal Imaging’s F-18 florbetaben (Neuraceq) for PET detection of beta-amyloid plaque in the brain. The company signed an agreement with IBA Molecular for the manufacture and distribution of the agent and word in the corridor is that multiple sites across Europe and the U.S. will be stocked by fall.
Obviously due to the U.S. Centers for Medicare & Medicaid Services national coverage determination to reimburse for amyloid imaging under strict coverage with evidence development, the majority of demand for amyloid and other agents for Alzheimer’s pathology is coming from biomedical companies conducting drug trials for the treatment of neurodegenerative disease.
Amyloid PET has been the darling of the neuroimaging set for several years now, but more recently tau PET has come into the spotlight and this year it stole the 2014 Society of Nuclear Medicine and Molecular Imaging (SNMMI) Image of the Year.
It is widely publicized that amyloid in the brain may not be the best agent for gauging progression and severity of AD. Tau imaging seems to hold greater promise in that arena. What does this mean for amyloid imaging?
To this enquiry, Marwan N. Sabbagh, MD, from Banner Sun Health Institute in Phoenix, responded: "Tau and amyloid imaging are shaping up to play valuable but distinct roles in managing the diagnosis and treatment of cognitive impairment and AD. Amyloid imaging will solidify itself as a diagnostic while tau will certainly be a marker of progression. This pairing begins to give clinicians and patients a path for disease management and, ideally, modification over the course of its progression."
The FDA has approved three amyloid agents, Neuraceq, F-18 florbetapir (Amyvid) and F-18 flutemetamol (Vizamyl). Europe has not yet approved Vizamyl, but Piramal announced in late February that Neuraceq received CE mark. “It could have been that Neuraceq was approved because our company has more of a European base,” said Andrew W. Stephens, MD, PhD, chief medical officer for Piramal Imaging, in an interview with Molecular Imaging during the SNMMI Annual Meeting in St. Louis.
As many experts have now stressed, a working diagnostic agent needs a therapeutic element to really take off. While it is still useful to have the diagnostic part for research and the ability to help patients and their families plan, the ultimate goal is to prevent or treat the disease.
Stephens indicated that not only are the two molecular imaging techniques complimentary rather than competing, but the success of tau radiopharmaceuticals may even depend on the success of amyloid agents in the current climate of conservative funding, regulation and reimbursement.
If one angle doesn’t provide a comprehensive enough picture of the pathology’s full complexity, would it one day be possible to integrate multiple targets and cover all the bases—diagnosis, staging, treatment and response in combined AD theranostics? Perhaps, but it is more likely that they will be used separately for completely different clinical ends: amyloid for early detection and tau for progression of disease.