NEW YORK ─ Norwegian firm Pre Diagnostics is preparing to enter the market for Alzheimer's disease testing using a monocyte blood immunoassay that analyzes the inside of innate immune cells to detect disease before there are symptoms.
The assay, called PreADx, uses intracellular measurements to monitor the ongoing clearance from the brain of amyloid beta (Aβ) peptides, a hallmark of Alzheimer's disease pathology.
The analysis of monocytes in the Pre Diagnostics assay represents a detection method unlike others used in blood-based biomarker tests, most of which employ plasma or serum as a sample, Charlotte Berg-Svendsen, the company's chief commercial officer, said in an interview.
Unlike other blood-based tests, PreADx provides a direct indication of how a dysfunctional immune system could lead to Alzheimer's disease, she said.
Blood-based diagnostic tests are already being developed to detect Alzheimer's disease before symptoms show up, with the aim of enabling early intervention to improve patient outcomes. Because they have the potential to be more affordable than brain imagining and less invasive than tests that require a spinal tap, developers of blood-based tests believe their assays could become part of the overall clinician toolbox for the early diagnosis of Alzheimer's disease.
"In Pre Diagnostics test, monocytes do the job of clearing amyloid beta plaques that build up in the brain," Berg-Svendsen said. "These monocytes are also part of the innate immune system, and for these reasons we believe that our scientific approach is particularly relevant for disease diagnosis."
The PreADx test detects amyloid beta peptides using a pair of monoclonal antibodies as part of an assay that currently runs on the Simoa immunoassay platform developed by Billerica, Massachusetts-based Quanterix. The test first isolates monocytes from a whole-blood sample and then uses the specially designed monoclonal antibodies to quantify the degradation of amyloid beta peptides. After isolation, the monocyte cells are lysed to reveal beta amyloid peptides, and then the Simoa immunoassay platform uses paramagnetic beads that bind to the PreDx monoclonal antibodies that are tailored to detect amyloid beta peptides. Detection antibodies that fluoresce in the presence of target analytes are added to the mix, forming an immunocomplex consisting of the paramagnetic beads, target peptides, and the detection antibodies.
When the isolated monocytes are loaded into arrays in a Simoa disc consisting of more than 200,000 microwells – each large enough to hold one bead ─ the immunoassay system reads the signal intensity on each bead and determines the biomarker concentration based on a calibration curve.
The startup said that a recent clinical study involving 62 patient samples showed that the test demonstrated clinically relevant performance with an area under the curve of .81.
Operating with the AUC of .81, the firm established sensitivity and specificity levels that are aligned with the requirements of different clinical settings, Pre Diagnostics' Chief Medical Officer and Cofounder Erik Christensen said in an interview.
In memory clinics, where, according to some estimates about 60 percent of all patients have Alzheimer's disease, the test's positive predictive value is 84 percent. For testing by neurology specialists, where about 50 percent of patients present for testing I'm not sure what this part means or why we are including it, the firm has established a positive predictive value of 77 percent and a negative predictive value of 73 percent. For the screening of healthy people aged 50 and older, the negative predictive value is 100 percent, the firm said.
The variation in sensitivity and specificity cut points enables flexibility in managing different populations of patients and their varying testing needs, Christensen noted.
He noted that in some cases, clinicians are looking to quickly screen patients for Alzheimer's disease and later confirm positive results with a cerebrospinal fluid (CSF) and other tests, while in other cases, such as selecting patients for a clinical trial, investigators rely solely on a blood-based assay and set its sensitivity cut point at the highest level possible.
The results of Pre Diagnostics' clinical study represent "a good start and this technique clearly has great potential," Dag Aarsland, chair of old age psychiatry at Kings College London, said in an interview.
A blood test that shows an AUC of .8, or above, is what clinicians operating in the field require and is seen as "very promising," said Aarsland, a long-time clinician and researcher with an interest in Alzheimer's disease and dementia who is not affiliated with Pre Diagnostics or the development of its test.
He noted that the firm's approach involving intracellular detection is "very different from other test procedures used to measure proteins and peptides" for Alzheimer's disease diagnosis and may provide advantages over other tests. Such as?? Nonetheless, the test will require further clinical validation to determine whether it can perform better than other blood-based Alzheimer's disease diagnostic tests that are being developed, he added.
Oslo-based Pre Diagnostics said it is scheduled to present the data from its multicenter study at the Alzheimer’s Association International Conference (AAIC) conference in Amsterdam in July. It has also embarked on a follow-up study that it plans to complete in about one year and is aimed at further validating the clinical utility of its test using about 300 clinical samples.
The company is also developing an assay for Parkinson's disease diagnosis, using its monocyte detection technology and alpha synuclein peptides as a biomarker for disease. Does its approach using monocytes provide advantages to differentiating the two diseases?
"We believe that the clinical utility of our tests includes finding and diagnosing patients with disease and also monitoring patients in clinical studies," Berg-Svendsen said. "These are dynamic markers and they show you how the disease pathology changes."
Pre Diagnostics anticipates obtaining CE marking for its assay in the second quarter of this year, which would enable it to begin offering a kit for sale in the European Union and other regions that accept the designation.
Following CE marking, the firm plans to target clinicians and researchers in Norway and the Nordic region ─ first using a testing service in a partner or its own? laboratory and later selling an IVD kit and testing service throughout Europe through distributors. The company said it has a longer term plan to enter the US market with a diagnostic industry partner.
Pre Diagnostics is further developing its PreADx assay that could lead to broader use of the tes, by making it compatible with high-throughput immunoassay instruments used for routine IVD testing.
The firm is in discussions with pharma and biotech companies developing Alzheimer's disease therapies, which would enable it to continue building evidence and documentation that supports the test's validity and clinical utility, Berg-Svendsen said.
Håkon Saeterøy, the firm's CEO, noted that it has thus far raised €6 million ($7.2 million), which includes €2.4 million in funding from a European Union Horizon 2020 research and innovation program that ends later this year, and it has opened a new funding round, expecting to raise between €5 and €10 million, that it anticipates closing this summer.
Håkon Saeterøy and Christensen founded Pre Diagnostics in 2013 by acquiring the rights to develop and commercialize a technology what technology? discovered at Akershus University Hospital.
The new financing would support the launch of its test as a laboratory service for the Nordic markets, and provide funding for the firm's continuing clinical validation initiatives as well as the development of its next assay for Parkinson's disease, Saeterøy said. He added that it also has its eye on developing a point-of-care diagnostic test that could be purchased without a prescription to detect neurological conditions.
As they await the potential approval of drugs that can help patients with Alzheimer's disease, clinicians currently prescribe cholinesterase inhibitors that can temporarily alleviate symptoms, and they make recommendations about lifestyle interventions, diet, sleep, exercise, and management of vascular risk factors. Though the clinical diagnosis of Alzheimer's disease in its moderate to late progression?? is about 80 to 90 percent accurate, a diagnosis based on earlier symptoms, such as mild cognitive impairment, is more challenging and creates a need for testing, including in vitro diagnostic tests and imaging.
A number of IVD diagnostic tests are in development or on the cusp of market entry.
In January, Fujirebio Diagnostics said it soon expects a decision about a submission to the FDA for clearance for its CSF-based Lumipulse G β-Amyloid Ratio (1-42/1-40) diagnostic test.
Fujirebio is developing blood-based Alzheimer's disease assays, and exploring the detection of amyloid-beta, neurofilament light, and phosphorylated tau biomarkers.
The barrier to collecting blood is far lower than for CSF, and industry observers believe that blood-based assays could be made available to screen patients for Alzheimer's during annual exams.
Last November, St. Louis-based C2N Diagnostics became the first company to bring a blood-based test for Alzheimer's to market and subsequently announced approval from the state of California to test patients samples in a CLIA-certified facility. Its test uses mass spectrometry to measures levels of amyloid beta (Aβ) and apolipoprotein E in patient blood. Further, Milan-based Diadem is developing a blood-based test, AlzoSure Predict, that uses an antibody to target changes in the p53 protein.