Six diseases reap benefits of biomarkers, genetic tests
Type 2 diabetes
A1c is the key biomarker for type 2 diabetes management. “This biomarker gives a three-month average of blood sugar control,” says Mohamed Jalloh, PharmD, a spokesman for the American Pharmacists Association and assistant professor at Touro University California, Vallejo, California. “When this number is high, we usually see patients with complications in their eyes, heart, kidneys, hands, and feet. If this number is too high, clinicians can determine which medications are more or less likely to work.”
In fact, the U.S. government looks at the percentage of patients who have a high A1c value to evaluate a health organization’s quality of care. “If the majority of its patients have an A1c above a certain goal, that’s an indicator that the organization might not be the best resource for getting someone to goal,” Jalloh says. This can potentially affect its reimbursement.
But Jalloh notes that some prescribers get too focused on treating a number instead of focusing on the best patient care. For example, insulin is one of the best agents to lower blood glucose. However, if too much insulin is used, patients can get very low blood sugars and have hypoglycemic symptoms (i.e., sweating, shaking). Using too much might not only increase the cost of treatment, but also worsen quality of life.
It can be challenging to assess the level of disease activity in children with chronic conditions. “Children vary in their ability to describe severity and frequency of symptoms, and external signs available on examination do not always correlate with disease activity,” says Steven Spalding, MD, chief clinical integration and medical officer and rheumatologist, Division of Pediatric Rheumatology, Phoenix Children’s Hospital, Phoenix. “Especially in pediatrics, biomarkers offer a unique additional data point to help determine disease activity and make decisions around the need for additional investigation or therapy.”
But how biomarkers are used in treatment decisions for juvenile arthritis is still evolving. “A gap exists between translating biomarker research into clinical practice,” Spalding says. “On the commercial side, not many companies offer laboratory tests that are efficient and effective enough in which to draw conclusions. Right now, biomarker tests are just one data point among magnetic resonance imaging (MRI), sedimentation “sed” rate or erythrocyte sedimentation rate (ESRs), and other diagnostic tools, that help determine if a patient has active disease.”
Given the limited experience with and availability of biomarkers in children with juvenile arthritis, their role in making decisions regarding investigation and therapy is quite small. “There is too much variation across genetics, especially among young children, to tie links from certain genes to functional outcomes,” Spalding says. “We’ve identified modifier genes in some pediatric patients, but we still find plenty of children with the same gene and variation in outcomes. To move to the genetic testing model, we would need to scale to diagnostic, risk-assessment type tools. Right now the jump from genes to smart conclusions is simply too wide. Most decisions for further evaluation or escalation in therapy are still driven by history and physical examination.”
But biomarkers can help to reduce the number of time-consuming and costly tests used to determine a patient’s diagnosis. “They could soon have the ability to rule out false diagnosis, eliminating the need for more assessment from MRIs and other tests,” Spalding says. “These more invasive tests can be especially difficult for children to undergo, with many children requiring sedation. This gives biomarkers an added value in the pediatric arena.”
Nathan Wei, MD, FACP, FACR, director, Arthritis Treatment Center, Frederick, Maryland, says biomarkers have not yet changed treatment decision making for rheumatoid arthritis. “While there is a movement touting the value of peripheral blood biomarkers, they are not an adequate reflection of what’s happening at the level of the joint,” he says. “We need better synovial tissue biomarkers.”
When synovial biomarkers are standardized, a simple synovial biopsy may permit the right type of treatment to achieve remission. A proper biomarker match would prevent the costly approach currently being used, which is to keep trying different biologics—in other words, trial and error.