Monday, October 6, 2014

Waiting for Word on a Match

It's hard to believe how many decisions are needing to be made, and yet we don't have a move date at this point. Originally, Seattle Care Center Alliance (SCCA) proposed October 20th as an "intake" date when they would start the process of preparing Ava for transplant, but they waved that off sometime last week.

Why? They are still determining if they have a good cord blood match for Ava. As you may know, bone marrow transplants need good matching for the best success. Doctors review at least 8 HLA markers for matching (though I think there are up to 10 different HLA markers). An 8 out of 8 match would be considered a "perfect" match. Transplants have also been done with a 7 out of 8 match.

With cord blood transplants, because cord blood cells are more immature than adult donor cells, the degree of matching doesn't need to be as stringent. They typically look at 6 different markers, and a 4 out of 6 match may be used in a transplant.

For Ava, 5 potential cord blood matches have been identified. (Hooray!) Four of these have a 4/6 match, and one has a 5/6 match. However, because Ava has already had a number of blood transfusions to date, her body has likely produced antibodies to certain blood types. Therefore, they are examining Ava's blood sample to see what type(s) of antibodies are present. This is important for them to determine which, if any, of the cord blood donors would be suitable for Ava. Simply going with the 5/6 match is not sufficient to determine a good match. Please pray for successful cord blood matching!

Once this is determined, they'll have more firm instructions on when Ava will head out to Seattle.

On another note, Mike mentioned in a previous post about Seattle's "stem cell expansion program", hoping that Ava gets selected for it. What he's referring to is a clinical trial being done at SCCA where they artificially expand or multiply the cord blood stem cells. Because units of cord blood contain relatively low amounts of cells, it's common to combine 2 different cord bloods from 2 different donors in order to have enough volume for a patient's transplant. But because Ava is little, the good news is that one unit of cord blood will be sufficient for her. Even so, the concern comes in after the transplant. The first month post-transplant is crucial. This is where they look for engraftment - when the transplanted cells start growing and multiplying in the patient, signifying a successful transplant. At the same time, the patient's immune system has been completely wiped out in preparation for the transplant (to put them in a better position to receive the donor cells), but this also means that they are at extremely high risk for infections - unfortunately a complication that can result in poor outcomes. Then there's graft-versus-host-disease (GVHD) when the newly transplanted cells start attacking the recipient's body. This can be acute or chronic, and range from mild to severe. In my limited understanding, I believe the clinical trial being done at SCCA is looking at expanding the cord blood stem cells... multiplying the cells so they have more of them on hand. During that crucial first month post-transplant, they can use these expanded cells in the recipient to help them better overcome risks for infection, etc. But this is only an investigative procedure, thus the clinical trial. Patients are randomized into the trial to either be part of the group that has cord blood cells expanded or the group that does not. They are hoping that Ava would be randomized into the group that does have this experimental stem cell expansion done.

They plan to do a bone marrow biopsy in Seattle as part of Ava's transplant preparation (so no biopsy will be done here). We continue to pray for MRD negative status heading into transplant!

Thanks for your prayers!

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