Initial Diagnostic Workup of Acute Leukemia Guideline

An interview with Dr. Valerie de Haas from Princess Máxima Center for Pediatric Oncology in the Netherlands on "Initial Diagnostic Workup of Acute Leukemia: ASCO Clinical Practice Guideline Endorsement of the CAP and ASH Guideline." ASCO fully endorses the CAP-ASH guideline on initial diagnostic work-up of AL and includes some discussion points according to clinical practice and updated literature.

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Hello and welcome to the ASCO Guidelines podcast series. My name is Shannon McKernin and today I'm interviewing Dr. Valerie de Haas from Princess Máxima Center for Pediatric Oncology in the Netherlands, lead author on "Initial Diagnostic Workup of Acute Leukemia: ASCO Clinical Practice Guideline Endorsement of the CAP and ASH Guideline."

Thank you for being here today, Dr. de Haas.

Thank you.

So first, can you give us a general overview of what this guideline covers?

Well, yes. The laboratory evaluation of patients who are suspected of having acute leukemia is very complex, and it has evolved significantly with the incorporation of advanced laboratory techniques. The traditional backbone of initial workup of AL, of acute leukemia, is composed of ctyomorphology, cytochemistry, immunophenotyping, and molecular cytogenetics.

These techniques are the backbone of the initial diagnostic workup of acute leukemia. This is leading to risk stratification and fine tuning of the therapy by molecular signatures. The advanced molecular diagnostics, such as next-generation sequencing, has become more important in the diagnosis and in the risk stratification of acute leukemia.

This guideline is meant for both pediatric and adult patients, and it was initially published in 2017. This year, we reviewed this guideline, and we have taken into account two important developments.

First, since 2017, we've seen that there are major advances in molecular techniques and also that we can identify and validate new molecular markers. And those two events have contribute to a better risk stratification. And the second development is the effect that the WHO classification was revised in 2017 which also has led to new risk recoveries and refined subclassifications.

So what are the key recommendations of this guideline?

Well, in total, we have reviewed 27 guideline statements by the ASCO endorsement expert panelists. And discussion points are used to summarize issues that were identified from the updated literature. The ASCO expert panel determined that the recommendations from the guideline as published in 2016 are clear, thorough, and they are based upon the most relevant scientific evidences.

We fully endorse the CAP-ASH guideline on initial diagnostic workup of acute leukemia. And we decided to include some discussion points according to clinical practice and according to the updated literature. In fact, we identified four categories of key recommendations. The first one is the initial diagnostics focusing on basic diagnostics and determination of risk parameters.

This concerns, in total, about 11 guideline recommendations, and they give an overview of the initial workup varying from the collection of the clinical history of the patient to initial basic diagnostics by cytomorphology, flow cytometry and molecular cytogenetic analysis of peripheral blood, bone marrow, and cerebrospinal fluids.

Secondly, the second category were molecular markers and MRD detection, and they were addressed by 10 of the recommendations. And these recommendations give a structural overview of the molecular and cytogenetic workup for acute lymphoblastic leukemia versus acute myeloid leukemia identifying different prognostic markers.

Also, the detection of MRD is taken into account in this recommendation. There is a major difference between children and adults, and this part is given most attention in the discussion part as the developments have been major during the past few years.

The third one is the context of referral to another institution with expertise in the management of acute leukemia. This is addressed by four recommendations, emphasizing the point that referral to an institution with specific expertise is of major importance for the central workup of acute leukemia.

And finally, the final reporting and report keeping is reflected in three recommendations, mainly supporting conclusions from 2017 which were describing the fact that the complete report with basic diagnostics in one central report should be available within 48 to 72 hours. And this should be followed by complete, final, comprehensive report in one or two weeks.

So can you tell us about those discussion points that were made and why the panel decided to include these?

The discussion points include mostly issues regarding diagnostics that involve flow cytometry and molecular techniques as addressed in part one and two of the guidelines. We think that the cytomorphologic assessment is essential for initial diagnosis of acute leukemia.

Multicolor flow cytometry using 8 to 10 colors has led to a better distinction between myeloids, lymphoid, and mixed lineage blast origin. Even when the number of cells are limited, for instance in CNS involvement, fine needle aspirate of extramedullary leukemic infiltration, or skin biopsy for leukemic cutis.

Also, it was suggested to better assess the central nervous system involved in leukemia. The expert panel recommends the immunophenotyping studies as an additional detection technique next to the cytomorphological examination of cytospins and particularly for those with a low level involvement of acute leukemia that cannot be well addressed by a morphologic examination only.

The TDT immunohistochemistry staining of cytospins has alternatively been used for detection of CNS disease in AML and evaluation of CSF by multicolor flow cytometry has been recently adopted in some centers. Flow cytometry, using at least six, but we now use in some laboratories, even 8 to 10 colors has led to a much more specific in tentative diagnosis. And this has improved the detection of CNS involvement.

The use of molecular tools, for instance, polymerase change reaction, PCR, NGS for low-level CSF involvement is still under study, and therefore, we did not recommend this in our discussion.

Regarding the molecular markers and MRD detection, the discussion here was mainly based upon the results of translational research supported by better molecular detection techniques. And those molecular diagnoses have been developing in the past few years with the inclusion of many more molecular markers. And they included one of the key diagnostic criteria in the revised WHO classification, which was revised in 2017. And we made substantial changes that have been made in the ASH-CAP guidelines concerning molecular diagnostics.

Those newly identified targets by advanced molecular techniques give possibilities for better risk stratification. Some examples of better molecular characterization of acute lymphoblastic leukemia are, for instance, additional testing for MLL translocations. Furthermore, we can look in patients with T-ALL for NOTCH1, and FBXW7 mutations.

The Ikaros family zinc finger gene, the IKZF1 gene is frequently deleted in adults as well in children with B-ALL. And it was shown to have an independent prognostic significance and was also associated with poor clinical outcome.

In the current text of the current risk that the protocols IKZF1 should be regularly included in the screening panels for all ALL patients.

If we look for examples for better characterization of AML, acute myeloid leukemia, we have found an increasing number of additional cytogenetic aberrations, like for instance FLT3 ITD which is associated with poor outcome.

Another example is appropriate mutational analysis for kids, which can be detected both in adult patient as pediatric patients with a confirmed core binding factor acute myeloid leukemia. So this is myeloid leukemia with a translocation A21, RUNX1, or inversion 16.

This recommendation is very strong in adults, whereas in children, this prognostic fact impact remains unclear. So there have been proven several publications which refer to a similar prognosis for children and others who refer to a poor prognosis in comparison to known mutated genes. So we suggest to test for this mutation in adults, especially, but also in children to learn from it.

Finally, emerging evidence supports molecular studies as principle test for monitoring minimal residual disease of acute leukemia. And there are several key molecular markers that are included in the initial workup, which will be carried on for monitoring MRD, for instance, PML- RAR-alpha, RUNX1-RUNXT1, CBFB-MYH11, and NPM1, CEBP-alpha and others.

Beside those aforementioned markers, it's very important to screen for other molecular markers that have predictive or prognostic value in the individual. And it is possible to use them for MRD. We have found a recent consensus from the European Leukemia Net MRD Working Group, who was proposing that for detection of molecular MRD, and they refer the RT PCR platform to NGS and digital PCR platforms.

Although all those molecular techniques have been developed very quickly and it is very tempting to use them for initial diagnostics, currently, not all laboratories will have all those techniques available. So the expert panel strongly advises understanding to make distinction between diagnostic that are needed in the first phase to start treatment and subsequently, treatment stratification, in contrast to the usual dose findings in a broader research.

For instance, available karyotyping, FISH, PCR techniques, if possible, NGS can be used in the initial start of treatment, whereas techniques like whole exome sequencing, whole genome sequencing, RNA sequencing, and epigenomic studies are meant for a broader research.

And finally, how will these guideline recommendations affect patients?

Well, in the end, the patients will receive better and especially, more personalized treatment. If we have results available within two weeks from diagnosis, it will be possible to better identify which basis will better benefit from more intensified and more personalized treatment, whereas others may need less intensive treatment with less toxicity.

If you use traditional techniques to do this supported by molecular techniques like karyotyping, FISH, and PCR techniques, and in the end, following MRD to see which patients are responding to treatment, MRD detection will help to identify these patients and stratify them finally to the best treatment.

Great. Thank you for your work on this important guideline, and thank you for your time today, Dr. de Haas.

OK. Thanks a lot.

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