【Wednesday Literature Reading】Professor Jia Yujiao| Big Coffee Commentary: Perfection, from the 2022 BSH acute myeloid leukemia laboratory testing practice recommendations to see the latest progress of ASH

Sampling considerations

Patients with suspected AML should have a bone marrow (BM) examination (puncture and trephine biopsy).

For patients presenting with a high white blood cell count, peripheral blood (PB) may be used instead of BM for diagnostic testing
.
Such regimens may be more appropriate for older/frail patients or those in
whom supportive care is the best treatment regimen.
The test sampling requirements are detailed in Table 2
.

Table 2 Sampling requirements

BM: bone marrow, CNS: central nervous system, CSF: cerebrospinal fluid, EDTA: ethylenediaminetetraacetic acid, FISH: fluorescence in situ hybridization, MRD: measurable (tiny) residual disease, PB: peripheral blood, RNA: ribonucleic acid
.

morphology

In the 2022 revision of the WHO AML classification, only the diagnosis of AML without a genetic abnormality definition (DGA) requires a BM or PB blast count ≥ 20%.

For AML with DGA, a blast count >of 20% is no longer required for diagnosis, and no specific blast cut-off value has been set, with more emphasis on the correlation
between morphological results and molecular genetic studies 。 Similarly, the AML ICC, published in 2022, proposes a lower standard of 10% for blast counts of AML with DGA, ≥10%, and MDS/AML for AML subtypes with MDS-associated gene mutations and for PB or BM with PB or BM with AML
subtypes without DGA but with MDS-associated cytogenetic abnormalities.

Morphological recommendations

• A bone marrow aspiration and trephine biopsy should be performed, and at least 200 nucleated cells should be examined to diagnose AML
  .
  

• Rapid communication of morphological results to specialized laboratory personnel is important for further testing, especially if APL or core binding factor (CBF) AML is suspected

Flow cytometry

Immunophenotyping by multiparametric flow cytometry (MFC) is essential
in diagnosis, mitigation assessment, and suspicion of recurrence.
When central nervous system involvement is suspected, cerebrospinal fluid examination
is indicated.
8-color MFC is the current standard detection protocol, and it is expected that 10-color MFC will become a routine detection scheme
in the next few years.
MFC-MRD in AML is used for post-remission BM to provide additional prognostic information after induction chemotherapy and before transplantation, as well as diagnostic information
at other time points.
Sample requirements for MFC testing are shown in Table 2
.

Flow cytometry recommendations

• Flow cytometry is key to diagnosis and post-remission assessment and requires rapid reporting
  .
  

• The diagnostic report should document whether AML cells are CD33-positive
  .
  

• Blastoplasmoid dendritic cell tumors (BPDCNs
  ) should be considered in the diagnosis of AML typing by flow cytometry.
  

• For flow cytometry MRD monitoring, diagnostic samples should be identified with the preferred traceable MRD target
  .
  

genetics

A comprehensive genetic profile, including cytogenetic and molecular genetic testing, is an integral part of the diagnosis and classification of
AML.
Detection of disease-specific abnormalities is critical
for diagnosis and recurrence by aiding accurate diagnosis and providing prognostic information for risk stratification.

Accurate and rapid diagnosis based on genetic characteristics such as cytogenetically defined subtypes or specific mutations (e.
g.
, FLT3 and IDH1/2) facilitates timely and appropriate therapeutic interventions
.
Identifying characteristic genetic lesions also determines which patients are candidates for molecular monitoring
of residual disease.

Cytogenetic testing
is mandatory for diagnosis and recurrence.
Routine karyotyping can be supplemented with rapid fluorescence in situ hybridization (FISH) detection to rapidly identify major lesions associated with various AML subtypes, but in the absence of diagnostic results, FISH must be supplemented by rapid karyotyping
.

With the continuous development of genetic disease classification, amplified molecular profiling such as rapid whole genome sequencing or RNA-based NGS will play an increasingly important role
in AML diagnosis.

Identification of disease-causing variants using NGS panels containing CEBPA, TP53, FLT3, IDH1, IDH2, ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, DNMT3A, WT1, and ZRSR2 will facilitate better AML genotyping and ELN 2022 risk grading
。 Testing laboratories have a responsibility to use reliable NGS methods to detect typical mutations in mandatory targets or to provide alternative, quality-assured single-target detection
.

Of note, robust identification and confirmation of driver variants identified by genetic testing alone may be somatic or germline mutations is critical
to recognizing that such variants are highly operable germline cancer susceptibility genes.
In addition, emphasis should be placed on the identification of familial susceptibility to haematological tumors, particularly when considering transplantation from a donor of interest, and more extensive testing
is needed.
In patients with clinical manifestations or family history suggestive of AML susceptibility syndrome or hereditary bone marrow failure, prior germline testing
may be required.
This test is usually performed using large-scale NGS analysis
.

Genetic advice

• Cytogenetic and molecular genetic analysis is essential
  for diagnosis and recurrence.
  

• Rapid identification of CBF-AML, FLT3-ITD, and FLT3-TKD mutations is also important
  .
  

• Complete routine cytogenetic analysis needs to be performed
  within 7 days of sample receipt.
  

• If a suspected germline variant is found in a cancer susceptibility gene, it should be clearly emphasized
  in the genetic report.
  

Expert reviews

AML is a molecular and clinically heterogeneous ^disease2
.
Bone marrow morphology, immunology, cytogenetics, and molecular biology are the basis of
AML diagnosis and treatment.
With the advancement of detection technology, the understanding of the molecular genetic characteristics of AML has been further deepened, and precision diagnosis and treatment according to mutational targets has gradually become a research hotspot
.
However, only a few gene mutations have developed corresponding targeted drugs, and IDH1 is one of ^them3
.
IDH1 mutations occur in approximately 6–10% of AML ^patients4
.

The most widely used and mature technique for detecting polygenic mutations such as IDH1 is NGS
.
Fresh bone marrow, peripheral blood, or tissue samples should be retained at the time of initial diagnosis for NGS testing, and those who do not survive should use bone marrow DNA samples saved at the time of initial diagnosis for testing
.
The bone marrow collection amount should be 1-3mL, the peripheral blood collection volume should be 3-5mL, and it is recommended to refrigerate and transport at 4 °C within 24 ^hours5
.
In addition to the consensus on gene mutation detection, China has also released the Chinese Expert Consensus on the Detection and Clinical Interpretation of AML Minimal Residual Diseases (2021 Edition)⁶, but there is still a gap between the construction and management of the domestic AML-related blood disease molecular detection platform and the laboratory testing practice recommendations for acute myeloid leukemia in 2022 BSH, and there is still a lack of systematic guidelines or consensus
for AML molecular diagnosis.

In response to IDH1 mutation, the first powerful inhibitor targeting IDH1 mutation, ivothenib, has been widely used in the first-line and second-line treatment
of IDH1-mutant AML patients at home and abroad.
This year, based on the results of a global, double-blind, randomized, placebo-controlled phase III AGILE study (NCT03173248), a new indication of IVO, ivosnib in combination with azacitidine for the treatment of patients with IDH1 mutation-naïve AML 75 years of age and older or who cannot receive intensive chemotherapy due to other comorbidities, was also approved
by the FDA.

In the 64th Annual Meeting of the American Society of Hematology (ASH), which will be held December 10-13, 2022, the results of the sub-results of the AGILE study will be presented soon, among 72 patients with undiagnosed IDH1 mutation AML treated with ivounib plus azacitidine, all baseline non-DTA (DNMT3A/TET2/ASXL1) mutations were suppressed below the detection limit (mutation clearance), of which 65% patients achieved complete response or partial hematologic recovery (CR/CRh), and IDH1 mutations were not detected in 75% of relapsed ^patients4
.
Thus, ivonicib combination therapy confers deep and durable remission
associated with IDH1 mutation clearance and baseline comutation.

In short, the implementation of more accurate and standardized clinical examination, especially molecular genetic testing is crucial, the gene mutation detection standards specified in the ELN recommendations should be further implemented into clinical work, adopt the blood molecular testing guidelines issued by BSH and other authoritative institutions, and do a good job in the management of molecular laboratories to achieve the corresponding dosing strategies for people with different characteristics and improve their long-term survival
.

References:

1.
Mehta P, Telford N, Wragg C, et al.
A British Society for Haematology good practice paper: Recommendations for laboratory testing of UK patients with acute myeloid leukaemia.
Br J Haematol.
2022 Oct 24.

2.
Yang X, Wang J.
Precision therapy for acute myeloid leukemia.
J Hematol Oncol.
2018 Jan 5; 11(1):3.

3.
Sbihi AA, Reddy SN, MBBS, et al.
Real-World Outcomes of IDH Mutant AML Patients Treated with or without IDH Inhibitors.
Poster on ASH 2022 (2755).

4.
Döhner H, Marchione DM, Choe S, et al.
Molecular Characterization of Clinical Response and Relapse in Patients with IDH1m ND-AML Treated with Ivo+AZA in the AGILE Study.
Oral on ASH 2022 (223).

5.
Hematological Oncology Professional Committee of Chinese Anti-Cancer Association, Hematology Branch of Chinese Medical Association, Pathology Branch of Chinese Medical Association.
Chinese expert consensus on the application of next-generation sequencing technology in hematological tumors[J].
Chinese Journal of Hematology,2018,39(11): 881-886.

6.
Experimental Diagnostic Group, Hematology Branch of Chinese Medical Association.
Chinese expert consensus on detection and clinical interpretation of minimal residual disease in acute myeloid leukemia (2021 edition)[J].
Chinese Journal of Hematology, 2021,42(11): 889-897.

NPM-CN-HEMA-249-20231123

Editor: May

Reviewed: Janet

Typesetting: Uni

Execution: Uni

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