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An Expert Explains CLL FISH and Flow Tests

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Published on February 13, 2019

How do doctors get a clear picture of a CLL patient’s diagnosis and disease characteristics? What tests are recommended soon after diagnosis? Chronic lymphocytic leukemia (CLL) expert Dr. Jennifer Brown, from the Dana-Farber Cancer Institute, discusses how a healthcare team evaluates patients upon diagnosis and explains how results from the FISH and FLOW tests are used. Watch now to learn more.

Provided by CLL Global Research Foundation, which received support from AbbVie Inc., Gilead Sciences and TG Therapeutics.

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Transcript | An Expert Explains CLL FISH and Flow Tests

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That's how you’ll get care that's most appropriate for you.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

Andrew Schorr:

So, Dr. Brown, let’s just find out. When somebody comes to Dana-Farber today, what testing do you do to get a clear picture of their situation? And also, be able to follow people as we learn more about CLL.  

Dr. Brown:                  

Right. So, we do have quite an extensive evaluation, right, at initial presentation or diagnosis, and that’s why many people do come to see us, to get that diagnosis. So, arguably, it’s informative, but it doesn’t alter what we do at that point. And so, the first thing, of course, is to make sure that we know for sure what the diagnosis is. And so, we need to make sure we have the flow cytometry test, it’s called. Which, we usually do just on blood to evaluate the cells that are in the blood, the lymphocyte cells, to make sure that they have the right characteristics to be CLL. And so…

Andrew Schorr:          

…flow cytometry, that’s different from the FISH test, right? 

Dr. Brown:                  

That’s right. Exactly. That’s different from the FISH test. And arguably, the FISH test is the other most important test to have early. And the FISH test looks at specific chromosome abnormalities that are characteristic of CLL. And it doesn’t look at the entire spectrum of chromosomes, but it’s specific ones that we know are important. And so, those include 13q deletion, which is the most common in CLL, and a little over half of patients with CLL. 

And generally, on the more favorable side, from a prognostic’s standpoint. We look at trisomy 12, which is an extra copy of chromosome 12. We look at loss of the long arm of chromosome 11, which is 11q deletion. And we looked at loss of the short arm of chromosome 17, 17p deletion, which affects the TP 53 gene, which people know, that is the only one of these that really affects our treatment decisions once a person needs treatment. Because, that has historically been associated with not as good responses to chemo immunotherapy, for example. So, we moved to novel agents immediately. 

As part of the FISH test, we also usually include a test for – a translocation between chromosomes 11 and 14, which is important to make sure that there is not overlap with another kind of lymphoma called mantle cell lymphoma. And that test also gives us information on whether there are any abnormalities of chromosome 14, which is also a recurrent abnormality in about 7 percent of CLLs in our patient cohort. 

Andrew Schorr:          

I just want to go over to make sure I understand. So, when we say cytogenetics, is that what you’re getting out of all of this? Is this from the blood, or do you need a bone marrow biopsy to do that? 

Dr. Brown:                  

So, generally we do this from the blood. It can be done on blood or bone marrow. But we don’t do a bone marrow biopsy just to do these tests. We can do them perfectly fine on blood. So, FISH is, I would say, a subtype of a cytogenetic analysis. The other component of a cytogenetic analysis that we do is to look at the entire chromosome complement in the cell. And this is something that historically didn’t work that well in CLL, because we actually have to get the cells to divide, and it’s hard to get them to divide. 

And so, a lot of times, we’d get false negative results because we wouldn't get cells dividing. But now, there’s a special stimulation technique that’s been developed to get the cells to divide better, and we can look at the entire chromosome complement, and find out if there are abnormalities in the chromosomes that are in other places that we don’t evaluate by the FISH test. And since we’ve had this additional way of looking at the chromosomes, we’ve been learning more in the last few years that the number of chromosome abnormalities is also an important prognostic feature of the CLL probably in the setting of treatment in particular.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.