MPN expert, Dr. Srdan Verstovsek provides insight into what factors determine whether MPN patients should undergo additional bone marrow biopsies and genetic testing over time.
Dr. Srdan Verstovsek:
We already know, everybody knows, I would think, that the living tissue does change over time. And when a patients have doubt, I tell them, “Look, my hair has not been grey all my life.” Everybody laughs. That happens with the bone marrow biopsy results, right? They change over time because the bone marrow does change over time. It’s not the same, and if you have the disease, disease cells, let’s call them malignant cells, they may acquire new mutations as they divide. If they already have some mutations that they’re present at the time of diagnosis, they are actually more prone to get more of those mutations over time.
And so, it may then be wise, and that’s what your question is about, to occasionally test patients and see whether there’s any change. Not perhaps in the number of fibers, or number of different cells, but genetically are there any new mutations which would make that disease perhaps more aggressive.
Unfortunately, the situation with repeated testing is complicated by price of the test. The testing can be done on blood, but it’s very expensive. We’re talking about thousands of dollars, and it’s not justifiable at the moment to do that every six months, or once a year for example, to see about any change because, it may not change what we do. It requires a clinical change, not just a genetic change for one to do something different, and something different would be referral to a bone marrow transplant, sooner rather than later.
So, first of all, repetitive testing would be useful in patients that are borderline for the decision of the transplant, not in everybody, because that’s the only intervention that would be affected by that testing. And then, even in these situations, you would need to have a clinically relevant abnormalities beyond just a new mutations.
That means a bigger spleen, or losing weight, or having profound anemia now. So, what basically this comes down to is, we follow the patients closely, and when there is a clinically relevant change, that would ask for a bone marrow biopsy and genetic testing, then we can justify that, and then we change what we do. So, it is cumbersome to sit tight and wait for a change, I understand that, but that’s the reality at the moment.