What It Means for Personalized Medicine. Measuring methotrexate polyglutamate levels may allow a doctor to adjust methotrexate doses to raise or lower the polyglutamate levels in each patient until it reaches a therapeutic level. But more research is needed, says Susan M. Goodman, MD, a rheumatologist at the Hospital for Special Surgery in New York City.

“There is significant overlap between polyglutamate levels in patients who have responded to methotrexate and those who haven’t, so standards would be difficult to define. And it takes months for methotrexate polyglutamate levels to reach a steady state, which lessens the usefulness in using the levels to guide therapy,” she says.

Vectra DA: A New Multi-Biomarker Test

What It Is. Vectra DA is a blood test that measures 12 biomarkers of RA. “Researchers began with 396 biomarkers and winnowed those down to the 12 that have the strongest and most consistent relationship with the disease activity of rheumatoid arthritis,” says Dr. Curtis. Some of the biomarkers include those that are of part of typical RA labwork such as c-reactive protein (CRP); interleukin 6, a driver of RA inflammation, and tumor necrosis factor, type 1 (TNF-R1), a chemical also involved in RA inflammation.  Vectra DA is not used to diagnose RA but to monitor disease activity and to help predict joint damage.

Why It’s Different. It’s the first test that measures multiple biomarkers for RA at once. “It reveals disease activity in a way that correlates with the way we usually measure it,” says Dr. Curtis. “It also does a pretty good job of predicting joint damage and flares that correlates with ultrasound and MRIs [magnetic resonance imaging].”

Dr. Curtis stresses that not everyone who has RA needs the test: “It’s only needed when there is uncertainty about how active the RA is or if the doctor is unsure whether to make a change in treatment.”

What It Means for Personalized Medicine. “It’s one more piece of information that a doctor can use to optimize the care of an RA patient,” says Dr. Curtis. He notes that while not every doctor has ready access to ultrasound or MRI equipment, this test requires a blood draw only, so it’s a more accessible test and may help predict joint damage as well.