AlloMap Molecular Expression Testing

New from XDx – Announcing…

AlloMap molecular expression testing is now available for cardiac transplants as early as 2 months post cardiac transplant!

For cardiac transplant patients, acute cellular rejection is most worrisome in the first months post transplant. As of Monday, August 21, 2006, AlloMap molecular expression testing is available to help you monitor patients as early as 2 months post cardiac transplant. When combined with patient assessment, AlloMap testing can provide the confidence you need to rule out acute cellular rejection.

Freedom from Future Rejection

A CARGO sub-study showed that patients with scores < 20 in the first 6 months post transplant were free from ACR ≥ 3A(2R) for the next 80 days (~12 weeks)¹.

¹ Data on File

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XDx Reference Laboratory Certification Information

Lab Directors:
Patrick Joseph, MD
Judith Wilber, PhD, D(ABMM)

CLIA Number: 05D1029609

California License
(CLF) Number: 332008

AlloMap Testing Overview

Cardiac transplantation is considered the definitive therapy for end-stage heart disease. Continuing advancements in organ procurement, surgical techniques, and immunosuppressive drugs have reduced mortality rates in the perilous early post-transplant period. There are nearly 20,000 living heart transplant recipients in the United States. Now, the focus of research and development is on improving patient management and quality of life.

The transplant management challenge

Patient survival depends on regular monitoring for allograft rejection and graft dysfunction. Physicians must also find the right combination of drugs to achieve a balance in the patient’s immune response—one in which there is enough immune suppression to ensure that the allograft is not rejected, but not so much that the patient develops side effects, infections, or malignancies. Since the early 1970s, endomyocardial biopsy has been the standard of care for rejection monitoring and drug titration management. However, it is well established in the literature that endomyocardial biopsy:

Is associated with increased risks (e.g. heart puncture, heart valve damage) to the patient

Is invasive and therefore, can be uncomfortable for the patient

Is a late indicator of rejection

Can be unreliable due to the potential for sampling error

Over the years, less invasive strategies for allograft monitoring have been investigated, but all have proven difficult to validate and implement.

The Human Genome Project advanced knowledge regarding the role of gene expression in disease.

Building on this new knowledge and advances in microarrays, qRT-PCR and bioinformatics, scientists at XDx together with clinical investigators from leading cardiac transplant centers postulated that a non-invasive method for monitoring for rejection using gene expression profiling could be developed for clinical use. This resulted in the design of a clinical study called CARGO, Cardiac Allograft Rejection Gene expression Observational study.

Based on samples collected in the CARGO study, XDx developed and validated AlloMap molecular expression testing. AlloMap testing is a multi-gene expression assay that provides important information not available from endomyocardial biopsy and that is directly applicable to clinical decision-making. Click here to learn more about the features of AlloMap testing. AlloMap testing is performed only at the CLIA-certified XDx Reference Laboratory in Brisbane, California.

Sample collection is noninvasive--peripheral blood for AlloMap testing can be drawn during a routine monitoring visit along with blood for other clinical laboratory tests.

The high negative predictive value (NPV) of AlloMap testing is its most salient performance characteristic. In conjunction with clinical judgment and assessment of graft function, AlloMap testing can reliably identify those patients who are at a very low risk for acute cellular rejection.

Negative Predictive Value (NPV)

Negative Predictive Value (NPV) is the probability that a concurrent biopsy will not show acute cellular rejection (grade ≥ 3A(2R)) for scores below the AlloMap score of interest. For example, in patients beyond 12 months post-cardiac transplant, using an AlloMap score of 34, the NPV for all scores below 34 is 99.2%. Thus, if the AlloMap test result was below 34, AlloMap testing would confirm absence of rejection in 992 out of 1000 cases and miss episodes of acute cellular rejection in 8 out of 1000 cases. If 34 is used as a threshold, test results with scores below it could be deemed as "low" risk for rejection.