ICML 2021 | Molecular diagnostics and reporting in lymphoid malignancies
Richard Rosenquist, MD, PhD, Karolinska Institute, Stockholm, Sweden discusses current and future routine molecular diagnostic methods in lymphoid malignancies. Current techniques include fluorescent in situ hybridization (FISH) technology, which can detect genomic aberrations, and Sanger sequencing, which can additionally detect gene mutations such as TP53 aberrations in chronic lymphocytic leukemia (CLL). Novel sequencing methods such as next-generation sequencing (NGS) and massive parallel sequencing (MPS) can detect larger number of genes simultaneously. Gene panels which can assess multiple mutations of interest have been developed and are currently being investigated in patients with lymphomas at the Karolinska Institute. This interview took place during the 2021 International Conference on Malignant Lymphoma (16-ICML).
Transcript (edited for clarity)
So today in routine diagnostics of lymphoid malignancies, we are using FISH technology to detect certain genomic aberrations. It can be deletions or amplifications or certain translocations. So these are standardized assays with probes that detect this specific genomic aberrations, and we hybridize these probes to either smears of peripheral blood or bone marrow or you can also use this probe on FFPE material...
So today in routine diagnostics of lymphoid malignancies, we are using FISH technology to detect certain genomic aberrations. It can be deletions or amplifications or certain translocations. So these are standardized assays with probes that detect this specific genomic aberrations, and we hybridize these probes to either smears of peripheral blood or bone marrow or you can also use this probe on FFPE material.
It can have diagnostic impact but also prognostic impact for the patients. And besides doing FISH analysis, we have also been doing Sanger sequencing for a number of gene mutations, for instance, TP53 gene screening in CLL. Also, that can be result of target and hotspot mutation detection for certain mutations.
But what has happened in the last 10 years is the introduction on next-generation sequencing or massive parallel sequencing and with new sequencing instruments, we can now detect or we can investigate higher number of genes simultaneously, so we can do targeted sequencing or we call it gene panels where we fish out the most interesting genes for certain entity and that we can then analyze at the same time. So for instance, in CLL, we have shifted from Sanger sequencing to next-generation sequencing of the TP53 gene. And in this way, many centers are not only investigating TP53 but also assess the mutation status of a number of other genes for research purposes.
For lymphoid malignancies at large, there have been different gene panels developed including genes that are recurrently mutated in different lymphoma entities. So these gene mutations can have diagnostic impact to refine the disease classification in lymphomas, but they can also have prognostic impact. So in Sweden, we have developed gene panel for lymphoid malignancies that include 252 genes that covers the most recurrent gene mutations in both B-cell and T-cell malignancies and we are testing this right now, the final testing before clinical mutation.
And we have a pilot study here at Karolinska, where we are using this panel on patients with lymphomas to see what it adds to screen this large number of genes in each case. And we have molecular tumor boards in order to sit down together the pathologists, the geneticists, the oncologists to discuss what does it add to do this broad gene panel for the individual patients?
So hopefully, this will inform us how we can continue using targeted sequencing also in lymphomas. But today, we are using this NGS-based screening primarily for TP53 mutation screening in CLL but also for some other hotspot mutations.
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