FDA has recently granted premarket clearance to the Plac test for Lp-PLA2 activity by in vitro diagnostics manufacturer diaDexus Inc, South San Francisco.

The new test is an enzyme assay for the quantitative determination of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in human plasma and serum. An analysis based on the National Institutes of Health-funded Reasons for Geographic and Racial Differences in Stroke study—a longitudinal study using a cohort of approximately 4,500 individuals with no prior history of cardiovascular events—previously demonstrated that elevated Lp-PLA2 activity levels are associated with a significant increase in risk for coronary heart disease.


Lori Rafield, PhD

“FDA’s clearance of our second test is an important step in achieving our vision of evolving from a single-product business into a multi-product company,” says Lori Rafield, PhD, interim executive chair and chairman of the board for diaDexus. “Our Plac tests—ELISA and now Activity—are the only FDA-cleared Lp-PLA2 tests to help identify the hidden risk of coronary heart disease, which includes heart attack. This new Plac Activity test has demonstrated robust analytical performance and can be used broadly by moderate-complexity reference labs, hospital labs, and physician office labs using a wide range of typical clinical chemistry analyzers, allowing us to meaningfully expand our customer base.”

The new test’s first indication for use is in conjunction with clinical evaluation and patient risk assessment as an aid in predicting risk of coronary heart disease in patients with no prior history of cardiovascular events, which is approximately 75% of the US population. According to the 2013 American College of Cardiology/American Heart Association guideline on the assessment of cardiovascular risk, more than 16 million Americans are at moderate risk for a first atherosclerotic cardiovascular disease event over the next 10 years.

Cardiovascular disease (CVD), which results in heart attacks, strokes and other cardiovascular events, represents the number one cause of death and disability in the United States. As many as 85 million Americans have an elevated risk of CVD, and in total, cardiovascular-related events cost the US healthcare system an estimated $400 billion each year.

Although it is common knowledge that high cholesterol is a significant risk factor for CVD, 50% of hearts attacks occur in patients with normal cholesterol levels. The majority of heart attacks and ischemic strokes are caused by plaque rupture, in which vascular inflammation plays a key role. For 30% of patients, sudden cardiac death is the first symptom of heart disease.

Lp-PLA2 is a vascular-specific inflammatory marker that is critical in the formation of rupture-prone plaque. When elevated, this enzyme indicates arterial inflammation, which is associated with increased risk for heart attack and stroke. The higher the level of Lp-PLA2, the higher the risk of a cardiovascular event, even when LDL is normal.

To commercialize its new test, diaDexus will use its established salesforce. Beginning in the first quarter of 2015, the company expects to start contracting and enabling new lab customers. Utilizing an established salesforce and a multi-faceted education-based strategy, diaDexus expects to begin providing laboratory customers and physicians appropriate information on the benefits of using Plac testing for patient risk assessment.

Evidence supporting the clinical utility of Plac Activity was based on data from the REGARDS study as well as the substantial peer-reviewed literature supporting Lp-PLA2 as an important cardiovascular risk marker. Demand is expected to be generated as physicians become familiar with and begin to order the test from diaDexus’ lab customers. Both of the company’s tests are covered under the established CPT reimbursement code for Lp-PLA2 testing.

For more information, visit diaDexus.