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News Archive
US FDA Staff Says Use for GE Imaging Drug Unclear
Washington (Reuters) - Aug 07 2009
By Susan Heavey
U.S. regulatory staff, in a memo released on Friday, questioned how well a GE Healthcare experimental imaging drug would help doctors more easily diagnose Parkinson's disease and other movement disorders.
The company, a unit of General Electric Co (GE.N), is seeking Food and Drug Administration approval to market its radioactive injectable drug, called DaTSCAN, for use with brain scans to help detect the loss of certain neurons but not to diagnose any specific conditions.
But "the ability of the data to support the proposed indication appears unclear," FDA staff wrote, adding that a doctor's ability to diagnose the problem played a role and that the drug may need to be used for a somewhat different indication.
Don Black, head of research and development for GE Healthcare Medical Diagnostics, said the FDA's concerns boil down to whether the product's labeling should say it provides anatomical information or information on how well the neurons function.
He added the company was willing to work with the FDA to finalize DaTSCAN's label.
"It's really up to the physician to make a diagnosis ... the diagnostic test is just part of that information" a doctor needs, in addition to a patient exam and other details, he told Reuters.
FDA staff also questioned the company's studies overall, saying they "are inconsistent with the type of design and conduct usually anticipated" for imaging agents.
It also said it was unclear how useful the drug would be for doctors, saying the company's studies were not designed to show how the drug's use with scans could help make assessments.
The FDA, which released the memo ahead of an advisory panel meeting on Tuesday to discuss the drug, said it would raise those issues with its outside experts at the meeting.
DaTSCAN combines ioflupane, a molecule that binds with the dopamine transporters in the brain, with radioactive iodine and is used in combination with single photon emission computed tomography, or SPECT, imaging in patients who show signs Parkinson's or other disorders such as dementia and palsy.
Such conditions are often marked by fewer dopaminergic neurons, which provide the brain its main source of the dopamine, a critical chemical for the central nervous system.
In a separate memo also released on Friday, GE Healthcare officials said that because so many neurons are lost even before symptoms occur, images from patients already showing signs of disease "are easily recognized and quantitative image analysis is therefore not needed."
"DaTSCAN would benefit patients and physicians in the USA by helping to improve the ... diagnosis of both movement disorders and dementias," the company wrote. DaTSCAN was cleared for use in Europe in 2000 and is approved in 32 countries, it added.
The FDA said it will ask the panel to consider possible indications for use of the scan, saying the distinctions are important because "a test that detects loss of 'functional neurons' could be seen by doctors as carrying more weight than one that detects certain abnormalities.
It will also ask whether the drug's benefits were worth its possible side effects, including headache and nausea.
FDA officials will weigh the panel's recommendations before later deciding whether to approve DaTSCAN. It usually, but not always, follows its panelists' advice.
