How Vectra DA works*
Vectra DA has been validated to assess RA disease activity. It works by measuring the levels of 12 important proteins in your blood. Those levels are then put into a calculation to get the Vectra DA score — a single number between 1 and 100 (lower is better). Because the test is scored as a single number, Vectra DA may help in discussions with your doctor as you work together to determine a specific treatment goal for management of your RA. It does not replace evaluation of your signs and symptoms but adds to the picture and gives you a quantitative measure of your RA biology. It has not been studied for use in predicting which specific therapy or class of therapy will work for you.
One way to think of Vectra DA is like the value of a thermometer. Before the advent of the thermometer, mothers would check their children for fever by holding a hand against the child’s forehead to sense whether or not the child’s skin was warmer than their own. If it was warmer, mom would assume the child had a fever, and certain steps would follow that included bed rest and fluids. Later she would feel the child’s head again, and then she would perform an interesting calculation: does the forehead feel warmer, cooler, or the same as it did when she checked it the first time?
Now, accurate and precise digital thermometers have replaced mom’s hand, and caregivers can be sure of actual body temperature; and by repeating the procedure at appropriate intervals, caregivers can truly assess if the fever is getting better or worse over time. The additional clarity provided by these simple thermometers has hugely improved the quality of a mother’s assessment—and made the hand nearly obsolete as a tool for determining body temperature.
Just like that digital thermometer, Vectra DA can help transform the way a patient’s disease is monitored. It provides a quantitative measure of your RA disease activity that complements your doctor’s assessment of your signs and symptoms.
While other lab tests may measure inflammation indirectly (such as erythrocyte sedimentation rate [ESR]) or measure a single inflammatory protein (such as C-reactive protein [CRP]), Vectra DA is different. It measures 12 key protein biomarkers that represent multiple biological pathways, giving you and your doctor a more comprehensive understanding of RA.
*Includes excerpts from "A new era for rheumatoid arthritis." Women.
www.awomanshealth.com. Fall 2010; 81-83.
A biography of biomarkers
A biomarker is a characteristic of the body that can be objectively measured and evaluated and is an indicator of normal or abnormal process or disease. Types of biomarkers include proteins, genes, and other molecules.
The 12 biomarkers measured in the Vectra DA test were carefully chosen after a lengthy screening process.
Crescendo first made sure to look broadly at RA biology. Using the scientific literature, databases, and early experiments, 137 proteins were selected for screening in clinical studies. This list was narrowed down to the 12 biomarkers found to have the best ability to evaluate RA disease activity in multiple studies of more than 1,100 patients. Another study was done to confirm these results in 230 new patients.
Vectra DA combines the concentrations of these 12 biomarkers into a single score that relates to the level of disease activity. Knowing this score can help you and your doctor manage your RA.
The 12 Vectra DA biomarkers
VCAM-1 (vascular cell adhesion molecule-1) plays a role in the interaction between cells, blood vessels, and connective tissue in the joint. These interactions contribute to the build up of cells within joints affected by rheumatoid arthritis.
EGF (epidermal growth factor) is a growth factor produced by cells in RA joint tissue that can cause cell growth and inflammation.
VEGF-A (vascular endothelial growth factor A) is a growth factor produced in inflamed joints that contributes to blood vessel formation, fluid buildup, and bone erosion.
IL-6 (interleukin 6) is a major driver of RA inflammation, cartilage deterioration, and bone erosion.
TNF-RI (tumor necrosis factor receptor, type 1) is a receptor for TNF-alpha, which is another molecule that drives joint inflammation and destruction. TNF-RI is expressed on the surface of many different types of cells, where it joins with TNF-alpha to drive inflammation. It can also be released from the cells, in which case it neutralizes TNF-alpha.
MMP-1 (matrix metalloproteinase-1 or collagenase-1) is an enzyme that contributes to cartilage destruction in RA.
MMP-3 (matrix metalloproteinase-3 or stromelysin-1) is an enzyme that destroys components of cartilage.
YKL-40 is protein that helps regulate tissue remodeling and destruction.
Leptin is a hormone secreted by fat tissue, cells in the joint tissue, and bone cells. Leptin can contribute to inflammation and regulates bone remodeling.
Resistin is another hormone secreted by cells in the joint tissue and bone that contributes to inflammation and helps to control bone remodeling.
SAA (serum amyloid) is a protein produced by the liver in response to inflammation. SAA may also be produced by the joint tissue, where it can activate tissue and bone cells.
CRP (C-reactive protein) is also produced by the liver in response to inflammation. Elevated CRP levels are associated with an increased risk of cardiovascular disease.