WASHINGTON, Aug. 6, 2012 -- In a new study on amyotrophic lateral sclerosis (ALS) published today in the Journal of Clinical Investigation, which was funded in part by The ALS Association, and conducted by researchers at Harvard Medical School, Tufts Medical School, Brigham and Women's Hospital and Massachusetts General Hospital, scientists have identified a biomarker in the blood that signals the earliest stages of the disease. While further studies to validate this finding will be important, this exciting discovery suggests that the immune system plays an important role early in the disease process of ALS and may provide doctors with a means of monitoring the progression of the disease through a simple blood test.
ALS is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Eventually, people with ALS lose the ability to initiate and control muscle movement, which often leads to total paralysis and death within two to five years of diagnosis. There is no cure and only one drug approved by the U.S. Food and Drug Administration (FDA) that modestly extends survival.
Currently, the only way to track the progression of ALS is through clinical measurements, such as the ALS Functional Rating Scale (ALS-FRS) and measures of muscle strength, which fluctuate over the short term, leading to the need for long-term clinical trials with large numbers of patients. An objective biomarker that changes with the disease and in response to therapy offers the possibility of shorter and smaller trials, leading to faster discovery of new therapies. That kind of biomarker is exemplified by LDL cholesterol in heart disease, which indicates disease severity and improves with treatment.
"This new biomarker provides us with a tool to better understand the beginning stages of ALS and may allow us to track the disease with a simple blood test," said Lucie Bruijn, Ph.D., Chief Scientist for The ALS Association. "That is critical for developing new treatments. Furthermore, the immune system changes identified in this study may themselves offer new targets for treating ALS."
In this study, which was led by Howard Weiner, M.D., of Harvard Medical School and Brigham and Women's Hospital, researchers used the standard laboratory model of ALS, a mouse containing the mutant gene for SOD1. SOD1 was the first gene discovered to cause familial ALS, the inherited form of the disease.
In the mouse model, researchers found that a type of white blood cell, called a monocyte, developed a specific chemical "signature" in the very earliest stages of the disease, before the mouse had developed symptoms. That signature triggered those cells to move to the spinal cord, where they increased inflammation, an important component of the ALS disease process. A similar signature was seen in monocytes of ALS patients. Scientists targeted the signature on monocytes in the mice using antibodies, which typically identify and neutralize foreign objects. This process slowed disease progression, suggesting that it may be a promising lead for developing therapies for people suffering from ALS.
The study is published online in the August 6 issue of The Journal of Clinical Investigation.
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