VANCOUVER, B.C. – An investigational gene-based blood test identified prodromal Alzheimer’s disease with an accuracy of 81%.
The test is based on a panel of 25 genes active in biological processes associated with Alzheimer’s, Dr. Magnus Sjögren said at the Alzheimer’s Association International Conference 2012.
Michele G. Sullivan/IMNG Medical Media
Dr. Magnus Sjögren
The genes have functions that include regulating the processing of amyloid and tau, and are involved as well in mitochondrial transport and function, neuronal and brain function, inflammatory processes, and oxidative stress, said Dr. Sjögren, chief medical officer of DiaGenic, the Norwegian company that is developing the test.
Under development in Oslo, the test could be submitted to the U.S. Food and Drug Administration within 1 year. After submission, hopes are high for a swift approval, he said.
"If we can validate the test in a set of U.S. samples, we believe it could be approved in less than 2 years," Dr. Sjögren said in an interview. "We hope to be able to study it in samples from the Alzheimer’s Disease Neuroimaging Initiative [ADNI]."
A proof-of-concept study based on a 20-gene version had a 74% accuracy rate in identifying cases of mild cognitive impairment (MCI) that converted to Alzheimer’s dementia over a 2-year period. The study, conducted in 129 subjects, was presented at the 2011 Conference of Clinical Trials on Alzheimer's Disease (Poster P10).
Two versions of the gene panel have now been validated in two separate cohorts.
The first group consisted of 100 subjects: 50 with stable MCI, 25 with confirmed Alzheimer’s, and 25 age-matched healthy controls. They were followed for 2 years. In this group with 2 years of follow-up, the 20-gene panel successfully predicted prodromal Alzheimer’s with 82% accuracy, 80% sensitivity, and 84% specificity.
It was retested in another unique group of 75 subjects with MCI that converted to Alzheimer’s. In this 2-year study, the test successfully predicted conversion 70% of the time, with 69% sensitivity and 71% specificity.
Since then, the company has added five additional genes to the testing panel. When the new test was applied to this same group of 75 subjects, the overall accuracy rose to 81%, with a sensitivity of 77% and a specificity of 85%.
The test hasn’t been validated against any other diagnostic methods, including brain imaging or biomarkers, Dr. Sjögren said.
The original test to help in making a diagnosis of Alzheimer’s, which is approved in Europe, costs about $500, Dr. Sjögren said. He didn’t comment on the possible cost of a test that could identify cases of MCI/prodromal Alzheimer’s.
In Europe, he added, the Alzheimer’s test is used in physicians’ offices and provides results in a few days. Doctors and patients can then decide together which confirmatory tests to pursue.
The MCI conversion blood test, if approved, could be similarly used. "I believe it would be more economical than cerebrospinal fluid collection and certainly less invasive," he said.