Biomarkers are measurable biological signals that can help researchers track disease activity, predict how a disease may progress, and evaluate whether a potential treatment is having an effect.
In ALS, one of the most promising biomarkers is neurofilament light (NfL), a protein released when neurons are damaged that can be detected in the cerebrospinal fluid and blood. Higher average NfL levels are generally associated with faster disease progression in large groups, and NfL is increasingly being used in clinical trials to help researchers understand whether a potential therapy may be reducing underlying motor neuron damage. However, NfL alone cannot fully capture the complexity of the disease or reliably predict disease progression at the individual level.
To address this challenge of more specific biomarkers, researchers are increasingly turning to large-scale protein analysis, known as proteomics. By measuring hundreds or even thousands of proteins in blood samples, they hope to identify additional biomarkers that could reveal what is happening in the body before symptoms appear and provide a clearer picture of disease progression.
Predicting disease onset
A recent study led by Dr. Michael Benatar (University of Miami) analyzed more than 500 blood samples collected over time from 137 participants, including people living with ALS, healthy controls, and people carrying ALS genetic variants. Among the genetic variant carriers, 33 individuals later developed signs of ALS or frontotemporal dementia (FTD). Data from study was in part collected through the Pre-fALS study, an important platform to study presymptomatic ALS.
Using proteomics, researchers measured over 5,000 proteins in the samples, resulting in the identification of 92 proteins that changed prior to symptom onset. The researchers then used machine learning to narrow their findings down to a panel of 19 blood proteins, including NfL and other proteins linked to different biological processes involved in ALS.
The researchers found this panel was better than NfL alone at identifying people who were getting closer to developing ALS symptoms and estimating when those symptoms might appear, from as little as six months to as much as five years before onset. On average, the model could predict symptom onset within about 18 months, representing a meaningful improvement over previous approaches.
Importantly, these findings also add to growing evidence that biological changes related to ALS may begin years before symptoms become noticeable. Previous studies have identified increases in neurofilament light chain (NfL), changes on brain imaging, and other biomarkers in people at genetic risk for ALS before they develop clinical symptoms, indicating that the disease has a presymptomatic phase.
Tracking ALS progression
In another recent study by researchers at University of Oxford, more than 1,000 blood and cerebrospinal fluid samples from over 400 people living with ALS were analyzed. Using advanced protein analysis, they identified dozens of proteins linked to survival, including NfL, as well as other proteins, such as peripherin, EDA2R, and calcitonin.
The researchers then developed a nine-protein biomarker panel that reflected both the extent of disease and how quickly it was progressing. This panel predicted survival more accurately than models based on clinical measures and NfL alone. They also found that changes in certain proteins over time, particularly EDA2R and calcitonin, were associated with survival, suggesting they should be further investigated if they can help track disease progression as ALS advances.
A third recent study also aimed at using proteomics to find better prognostic biomarkers to accompany NfL, identifying the proteins GSN and IGFBP2 as key targets for further exploration.
The takeaway
Biomarkers that can help predict ALS progression and measure disease activity are urgently needed. NfL remains a very valuable tool to support stronger clinical trial design and outcomes, yet it still has limitations.
These overall findings suggest that combining multiple biomarkers, rather than just NfL or clinical measures alone, may provide a more complete picture of how we can more effectively study, understand, and treat ALS.
Additional research and validation are needed before these protein signatures can be used in routine clinical practice. However, all three studies represent progress toward more precise mapping of the biological changes associated with ALS, from the earliest stages before symptoms appear through to disease progression after diagnosis.