Easier, Noninvasive Diagnosis of Neurological Disorders

A growing number of laboratory companies have begun offering neurofilament light chain (NfL) blood tests as a cost-effective alternative to conventional methods of diagnosing and guiding treatment decisions for patients with neurological disorders. In January, Quanterix became the latest firm to validate a laboratory-developed NfL test, which it plans to launch before the end of the year.¹

The Diagnostic Challenge

Neurodegenerative conditions such as Alzheimer’s disease, Parkinson’s disease, Down syndrome dementia, multiple sclerosis (MS), and classical motor neuron disease (ALS) occur when nerve cells in the brain or peripheral nervous system lose function over time and ultimately die. Unfortunately, significant brain and nerve damage may occur before a patient exhibits definitive symptoms, particularly in elderly patients. As a result, preventive screening becomes imperative. 

However, conventional laboratory testing methods to screen for neurodegenerative disorders are less than user-friendly. Biomarkers for neurodegenerative disorders are found in the cerebrospinal fluid (CSF) surrounding the brain and spinal column. Extraction of CSF requires the use of lumbar puncture (aka, spinal tap), an invasive procedure in which a needle is inserted into the space between two vertebrae.

The Effectiveness of NfL Tests

Blood tests would be a cheaper, simpler, and less painful alternative. The good news is that recent studies show that levels of NfL, a protein in the blood that the body releases as a result of nerve damage, are a reliable biomarker for many kinds of neurodegenerative disorders. By contrast, NfL is not limited to a single disease the way other biomarkers are, for example, the phosphorylated tau (pTau) biomarker, which is specific only to Alzheimer’s.

A study from the National Institutes of Health (NIH) published in the American Academy of Neurology’s Neurology journal in August 2020 also showed that NfL was superior to other blood proteins such as glial fibrillary acidic protein, tau, and ubiquitin c-terminal hydrolase-L1 as a biomarker for mild, moderate, and severe traumatic brain injury (TBI).²

“This study confirms the sensitivity of serum neurofilament light chain and its value as a biomarker of choice for all stages of brain injury, even when measured months to years after a single mild, moderate, or severe traumatic brain injury,” noted study author Leighton Chan, MD, MPH, chief of the Rehabilitation Medicine Department at the NIH Clinical Center, in a news release.³

Less than a year later, the journal Nature Communications published another study that was partially funded by the NIH, concluding that a simple blood test using age-related concentration levels of NfL could accurately diagnose, although not differentiate among, a number of different neurodegenerative disorders, as well as measure the effectiveness of therapeutic treatments for them.

According to the authors, the study demonstrates “that plasma NfL is clinically useful in identifying atypical parkinsonian disorders in patients with parkinsonism, dementia in individuals with Down syndrome, dementia among psychiatric disorders, and frontotemporal dementia in patients with cognitive impairment.”⁴

The Emergence of NfL Laboratory Tests

Labcorp and Quanterix have led the way in launching laboratory-developed tests (LDTs) that use NfL levels in blood to diagnose multiple neurodegenerative disorders. On July 13, 2022, Labcorp announced the launch of its NfL blood test designed to make it easier for neurologists to identify and confirm the signs of multiple neurodegenerative diseases and brain injury, including ALS, dementia, and Parkinson’s disease, as well as concussions. There is no need for a spinal tap. The Labcorp test can be run on a standard blood sample taken at a hospital, doctor’s office, or one of the laboratory giant’s own patient service centers.

“NfL is a simple, objective blood test that provides direct evidence of neuronal damage,” noted Labcorp chief medical officer Dr. Brian Caveney in the press release announcing the launch. “In making this test widely available, Labcorp is supporting neurologists with a tool they’ve been asking for that enables faster diagnoses, better treatment decisions, and improved patient care,” he added.⁵

Quanterix has also been an early leader in the emerging NfL neurology test market. The Massachusetts-based firm has leveraged its Simoa technology enabling earlier biomarker detection in blood, serum, or plasma, along with the capacity to quantify proteins far lower than the limit of quantification (LoQ) of conventional analog methods, to develop NfL products in the neurological space. Last April, the company announced that it had secured US FDA breakthrough device designation for its Quanterix Simoa NfL digital immunoassay for evaluating the risk of relapse in relapsing-remitting MS (RRMS) patients.⁶

On Jan. 9, Quanterix announced the validation of a commercial version of its previous research-use only LDT quantitative NfL blood test. The NF-LIGHT Assay is broader than the RRMS product and can be used for identifying a number of neurodegenerative conditions, as well as other causes of neural or central nervous system damage. Quanterix will offer the LDT via its Accelerator Laboratory, a CLIA-licensed and ISO 15189-accredited laboratory.

And the company has even bigger NfL ambitions. “We see NfL as not only an important marker for neurodegenerative disease but also a critical measure of brain-related side effects during chemotherapy, CAR T-cell therapy, and stroke,” said Quanterix CEO Masoud Toloue in the press release announcing the validation. “Today is another translational step on our mission.”¹

Takeaway

By eliminating the need for lumbar puncture, NfL-based blood tests represent a simpler and less invasive alternative to current laboratory tests for diagnosing neurological disorders. The science suggests that NfL tests are accurate. Research has made it possible to develop tests covering multiple disorders, as well as neurological damage. While Labcorp and Quanterix have stolen the early march, other test makers are developing their own NfL LDTs. Those currently offering such tests include Siemens Healthineers and the Cleveland Clinic.

References:

1. https://www.businesswire.com/news/home/20230109005182/en/Quanterix-Expands-Laboratory-Developed-Test-Menu-with-Launch-of-Neurofilament-Light-Chain-Test
2. https://n.neurology.org/content/95/6/e623
3. https://www.nih.gov/news-events/news-releases/nfl-outperforms-other-blood-tests-predict-diagnose-traumatic-brain-injury
4. https://www.nature.com/articles/s41467-021-23620-z
5. https://www.businesswire.com/news/home/20220713005453/en/Labcorp-Launches-New-Test-to-Identify-and-Confirm-Neurodegenerative-Disease
6. https://www.quanterix.com/press-releases/quanterix-granted-breakthrough-device-designation-from-us-fda-for-nfl-test-for-multiple-sclerosis/