Clinical study shows association between Corus CAD blood test scores and cardiovascular event rates

CardioDx, Inc., a molecular diagnostics company specializing in cardiovascular genomics, announced today results from a genomic substudy of the NHLBI-funded Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) trial in nondiabetic patients receiving the Corus CAD blood test. The test integrates age, sex and gene expression into a single score (1-40 scale) corresponding to the likelihood of obstructive coronary artery disease (CAD). Findings from the substudy were presented at the 65^th American College of Cardiology Annual Scientific Meeting, on April 3, 2016, in Chicago, IL.

In this study, the PROMISE Trial investigators asked if a blood-based, age- and sex-adjusted, gene expression score (ASGES or Corus CAD), previously validated for the detection of obstructive CAD, was also predictive of CAD events. The primary analysis showed that cardiovascular event rates, as defined by the composite rate of death, myocardial infarction (MI), hospitalization for unstable angina, or revascularization, were associated with the Corus CAD test in a score-dependent manner: Patients with higher Corus CAD test scores ( > 15, n=1312 patients) had higher event rates that were statistically different from patients with lower Corus CAD test scores (1-15, n=1058 patients) (odds ratio of 2.6, p < 0.001). Additionally, the results from the substudy found that at 25-month median follow-up, the clinical event rates for patients with low Corus CAD scores (≤ 15), were low and no different from negative or normal noninvasive test results using either cardiac stress testing or coronary CT-angiography (CTA) (3.2% vs. 2.6%, p=0.29). This relationship between Corus CAD test scores and event rates remained significant after adjusting for common clinical risk factors using the Framingham Risk Score (FRS) and provided independent and incremental information beyond noninvasive test results (stress testing or CTA). Lastly, the increased risk of clinical events seen with higher Corus CAD scores were largely driven by an increased rate of revascularization procedures in this group, thus reaffirming that the likelihood of obstructive CAD (defined as > 70% stenosis by CTA) increases with Corus CAD scores.

The study utilized 2,370 non-diabetic patients from the PROMISE trial biobank repository. Almost half of the patients in the substudy were randomized to the CTA arm (n=1,137). In this group, 10.1% of patients (n=115 of 1,137) were found to have obstructive CAD, and a Corus CAD score > 15 was associated with increased obstructive CAD likelihood (OR 2.5, p < 0.001). Findings from the PROMISE Trial provide independent confirmation of the association between the Corus CAD test scores and the presence and extent of coronary artery disease in patients and the likelihood of obstructive CAD.

"Findings from this PROMISE substudy demonstrate the opportunity to use a simple blood test in the initial evaluation of symptomatic patients with suspected CAD to help clinicians determine next steps and make clinical decisions," said Deepak Voora, M.D. Assistant Professor of Medicine, Duke Center for Applied Genomics & Precision Medicine. "The lower likelihood of not only CAD but risk of revascularization procedures seen in patients with low scores suggests that the score, in conjunction with a physician's clinical assessment, could provide additional information to help physicians efficiently and effectively rule out clinically significant obstructive CAD in the outpatient setting."

"We are very excited to see that the results from the large genomic substudy from the NIH-funded PROMISE Trial independently corroborate findings from our earlier Corus CAD clinical studies on the clinical validity of the test in the evaluation of obstructive CAD. In addition, while we have seen that in previous studies that patients with low Corus CAD test scores have a very low likelihood of major cardiac events within a one-year follow up period, it is very reassuring that the PROMISE substudy results confirm and extend this finding with greater than two years of follow-up seen here," said Mark Monane, M.D., FACP, Chief Medical Officer of CardioDx. "Lastly, we note the finding that clinical outcomes among the patients with the low scores on the Corus CAD blood test (approximately 45% of the study patients) were no different from patients with normal cardiac stress testing or CT-angiography. Taken together, these three results highlight the characteristics of the Corus CAD test to safely and accurately help clinicians risk stratify symptomatic patients, so that patients can potentially avoid additional cardiac testing and procedures that may be potentially unnecessary."