Sunday, April 1, 2012

A is for Allomap Molecular Expression Testing

I have decided to participate in the Blogging from A to Z Challenge and since I have recently realized how much I DON'T know about heart function, heart diagnostics, etc. I have decided to use a theme of heart disease and  make it to treatment.  I will try not to boring and dry, and hopefully someone reading will find it somewhat helpful.

With our recent problems in the areas of biopsies  and the fact that she has only one access point for biopsies (as opposed to four), I've had a lot of people asking me about alternatives to biopsy.  One such alternative is the recent AlloMap Molecular Expression Testing - or the blood test for rejection.  Bean is not eligible for this alternative - one has to be at least 15 years of age.  So, she has a long ways to go.  But, I thought for those curious about this, I would share the facts as I know them.

Approved by the FDA in 2008, the test is designed to provide an alternative to invasive endomyocardial biopsy (what Bean gets) for those patients who are stable and asymptomatic.  The test only predicts probability of moderate/severe acute cellular rejection.  This is only one type of rejection.  The others are antibody-mediated rejection (AMR) and cardiac allograft vasculopathy (CAV).  The test can be used in conjunction with other clinical assessments (echocardiograms, EKGs and examinations) to judge whether an invasive biopsy is needed (negative numbers would be followed by a biopsy for more exact information).

The preliminary results of clinical comparisons between the AlloMap and biopsies is pretty impressive.  Over a four year period, from 2005 to 2009, the test was used on 602 patients in 13 transplant centers and results showed there was no inferior results when compared to biopsy for clinical outcome.  Now, all that technical language simply means that those having regular biopsies were no more likely to suffer acute rejection than those receiving the AlloMap instead.  Which is good news, but doesn't mean that this test does away with biopsies (because the way a patient is found to be stable and asymptomatic is through routine biopsies following the transplant - all the test subjects were at least six months post-transplant).  But, it will save individuals a lot of invasive procedures if they are doing well clinically and have no signs of rejection or other problems with the heart.

I would assume (although I don't know for sure) that there would still be a need for annual biopsies because it is during these that they test the elasticity of the arteries and other issues that are known to cause issues for recipients.  But, only having to have biopsies once a year instead of three times a year would be a very welcome change for us right now.  But, again, we aren't even in the running for this choice.  And I don't know if Bean's history of rejection (two 3s in the first year and a number of 1As post-transplant) would disqualify her as a candidate or not.  But, I guess I don't have to worry about that for at least 12 years.  I have spoken to a few people who are using this technique.  Some of them love it.  Some of them feel a little trepidation at trusting the results as much as they would a biopsy's result.

Anything that provides transplant recipients and their doctors more choices in treatment and evaluation seems like a welcome thing to me.  So, I hope that AlloMap continues to be successful and improve and maybe even gets approved for younger recipients so kids under 15 do not have to suffer so many of these invasive procedures!

So, that's today's A topic - AlloMap Molecular Expression Testing.  The information presented here came from the product's website and/or the wikipedia page for the product.


  1. I work for XDx, the makers of AlloMap. We are located in the San Francisco Bay area. You provided a great description of AlloMap – Thank you. I wish AlloMap was available to help Bean and other children under age 15, but there is not enough data about how to apply AlloMap to young children (and the physicians and FDA require such study data). The AlloMap test has been defined to perform in blood from adults, and results from blood samples taken from a developing child may perform differently. The kind of study needed to characterize AlloMap use in young children is very formidable because of the relatively small numbers and diverse conditions of the children that must be studied. Our scientists continue to search for ways to make AlloMap feasible for young children in the future.
    AlloMap is available for stable patients ≥15 years of age and >55 days post transplant. Many patients benefit from having fewer biopsies and avoiding risk of complications such as tricuspid valve damage or reducing exposure to imaging radiation. Each hospital’s transplant program has its own recipient management protocol that guides the frequency surveillance for rejection with AlloMap and biopsies. Currently there is considerable diversity of surveillance practices between centers. Only recently have guidelines been established by the professional society recommending best rejection surveillance practices, and AlloMap is part of the Clinical guidelines recommendations.

  2. Wow - thanks so much for the reply Annette! I am a big fan of fewer biopsies, but like you say, we have a while to wait! But, I'm glad for those who can have this relief.


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