Research and programs from the VA are advancing the benefits of pharmacogenomic treatments
A new study conducted by the US Department of Veteran Affairs (VA) showed that using pharmacogenetic testing to guide treatment for depression resulted in improved outcomes and fewer negative side effects from treatment. These results demonstrate the benefits that healthcare leaders are seeing when using pharmacogenetic testing (PGx) to guide prescribing decisions.
Led by David W. Oslin, MD, Assistant Professor of Psychiatry at the University of Pennsylvania Medical Center and Director of the VA’s VISN 4 Mental Illness, Research, Education, and Clinical Center (MIRECC), the research can be reviewed in a Journal of the American Medical Association article, titled, “Effect of Pharmacogenomic Testing for Drug-Gene Interactions on Medication Selection and Remission of Symptoms in Major Depressive Disorder.”
Highlights of VA PGx Study of Major Depressive Disorder (MDD)
The primary question addressed through this interventional clinical trial was, “Does provision of pharmacogenomic testing for drug-gene interactions affect selection of antidepressant medication and response of depressive symptoms in patients with major depressive disorder (MDD)?”
The study included nearly 2,000 patients over a period of 24 weeks and used data from more than 20 different VA centers. All the patients in the study received genetic testing taken using a cheek swab. Only half of the patients, however, had the results of their genetic testing transmitted to their provider.
“The genes we tested don’t actually relate to depression,” explained Oslin in a VA press release. “They relate to how a person metabolizes the drugs once they’re in the body. Some of these genes will cause the medications to metabolize much faster than normal. Others will cause the drugs to metabolize much slower than normal, which means you’ll end up with a lot of medication in your body.”
Oslin emphasized that the purpose of the test was to understand how the drug was metabolized, not if a patient would respond to it or not. “It’s important to realize that the test is not telling you whether the patient is going to respond to the treatment or not,” he said. “It’s telling me not to prescribe this medicine, or perhaps to adjust the dosing, because the patient doesn’t metabolize it well.”
By predicting how medications would be metabolized, clinicians were able to avoid medicines that had a high likelihood of causing negative side effects. Clinicians were also able to adjust dosages to avoid over-dosing or under-dosing patients, making treatment safer and more effective.
Economics of PGx Testing
One great benefit for healthcare organizations considering pharmacogenomic testing is that this testing is cost efficient. “The costs actually are very low because the results can be used over the patient’s lifetime,” Oslin said. “So you’re not talking about a test that has a shelf life of only five minutes. And there’s really no risk to getting the test. You’re just getting the cheek swab or a blood test. Cost is low, risk is low, and the population benefits are probably low. But overall, this test likely benefits some patients substantially.”
While the results of this study were meaningful, the genetic testing only benefited a small portion of the patients. “The results were not a slam dunk, and in fact, an important outcome of the study is that only about 15% to 20% of the patients had genes that would significantly interfere with the prescribed medication,” Oslin observed. “But I think the results favoring a positive effect on treatment, although small, will encourage providers to test patients and get this genetic information. Future research should explore if there are subgroups of patients who would benefit more from testing.”
The VA has played an important role in bringing pharmacogenomic testing to patients since the end of 2019 when it partnered with Stanford Health to create its PHASER (“Pharmacogenomic Testing for Veterans”) program. This program offers pharmacogenomic testing to any veteran, enhancing the availability of precision medicine for veterans. The PHASER program is continuing to expand since its inception, recently becoming available in central Ohio-area VAs, with the number of VA locations offering this service expanding.
The value that pharmacogenomics brings to improving personalized treatments continues to grow, thanks to innovation and research from the VA and others. Healthcare leaders should expect to see increasing improvements in outcomes as they apply new developments in precision medicine prescribing.