Acute Myeloid Leukemias: Clinical Guidelines

List of Abbreviations

allo-HSCT – allogeneic hematopoietic stem cell transplantation

ALT – alanine aminotransferase

AST – aspartate aminotransferase

auto-HSCT – autologous hematopoietic stem cell transplantation

ESBL – extended-spectrum beta-lactamases

HDAC – high-dose cytarabine**

HIV – human immunodeficiency virus

WHO – World Health Organization

HDPCT - high-dose combination chemotherapy

DNA – deoxyribonucleic acid

GI – gastrointestinal tract

IA – invasive aspergillosis

IPT – immunophenotypic study

BM – bone marrow

CT – clinical trials

CT – computed tomography

LDH – lactate dehydrogenase

MDS — myelodysplastic syndrome

LDAC – low-dose cytarabine**

MRD – minimal residual disease

MP – mercaptopurine

MPD – myeloproliferative disease

MS – myeloid sarcoma

AL – acute leukemia

ALL – acute lymphoblastic leukemia

AMLL – acute mixed-phenotype leukemia

AML – acute myeloid leukemia

APL – acute promyelocytic leukemia

CR – complete remission

PCR – polymerase chain reaction

РКИ – randomized controlled trial

RNA – ribonucleic acid

GVHD – graft-versus-host disease

BMT – bone marrow transplantation

LCE – level of confidence of evidence

US – ultrasound examination

GRS – grade of recommendation strength

CT – chemotherapy

CMV — cytomegalovirus

CNS – central nervous system

ECG – electrocardiography

EchoCG – echocardiography

FAB classification – French-American-British classification

FISH – fluorescence in situ hybridization

NCCN – National Comprehensive Cancer Network

** – vital and essential drugs

# – drug used outside of the indications, modes of administration, and doses contained in the medication's instructions for use (off-label)

Terms and Definitions

Acute myeloid leukemias (AML) are clonal neoplastic diseases of the hematopoietic tissue associated with a mutation in a hematopoietic progenitor cell, resulting in a differentiation block and uncontrolled proliferation of immature myeloid cells [1,2].

Assessment of treatment efficacy:

Complete clinico-hematological remission (CR) of AML is defined as a state in which the bone marrow aspirate shows no more than 5% blast cells with normal cellularity and a harmonious ratio of all hematopoietic lineages, absence of blast cells with Auer rods, restoration of peripheral blood neutrophil counts $\ge$1.0×10⁹/L, platelet counts $\ge$100×10⁹/L, and absence of extramedullary leukemic foci (central nervous system, skin) and splenomegaly. These parameters must remain stable for 1 month or more. CR is established without considering the data for "minimal residual disease" (MRD) detection using flow cytometry (immunophenotyping, IPT) or molecular biological methods (quantitative PCR, gene expression determination).

CR with incomplete recovery – complete remission with persistent neutropenia (<1×10⁹/L) and/or thrombocytopenia (<100×10⁹/L).

Complete remission (CR) with the absence of minimal residual disease (MRD(-)CR) – complete remission with the absence of a detected genetic marker or hematopoietic cells with an aberrant tumor immunophenotype in the bone marrow aspirate.

Minimal residual disease (MRD) – is a population of tumor cells that cannot be detected by light microscopy, but is revealed by more precise research methods capable of detecting 1 leukemic cell per 10⁴-10⁶ cells studied.

Treatment failures:

Resistant (refractory) AML – failure to achieve complete remission (definition above) after an induction block (AME/ADE/AIE).

When blasts are less than 15% in the bone marrow aspirate and there are no unambiguous signs of leukemic blasts (e.g., Auer rods), refractoriness must be confirmed using IPT and/or cytogenetic/molecular markers.

Unlike the AML treatment protocols of the late 20th and early 21st centuries, in which resistance was established after two courses of chemotherapy, modern protocols show that in patients who fail to achieve CR after an induction chemotherapy course, the risk of relapse is high even if CR is achieved after the second course.

Relapse – more than 10% leukemic blasts in the bone marrow or any extramedullary involvement at least 1 month after the establishment of the first complete clinico-hematological remission. Given the possibility of false diagnosis of relapse due to an increased content of B-lymphocyte precursors (hematogones), it is necessary to correlate blastosis, the "titer" of the detected molecular marker, and immunophenotyping.

Molecular relapse – detection of MRD by flow cytometry and/or PCR in two consecutive tests with an interval of at least 2 weeks, provided that an aberrant immunophenotype is analyzed or a molecular study is performed prior to therapy initiation.

Neuroleukemia – any number of blast cells in the cytopreparation not explained by contamination of the cerebrospinal fluid with peripheral blood due to a traumatic puncture; and/or symptoms of cranial nerve involvement or other neurological symptoms associated with chloroma growth. Intracranial and intraspinal epidural “chloromas” in the absence of leukemic cells in the cerebrospinal fluid are not considered neuroleukemia. The grading of CNS involvement status is determined by the treatment protocol.

Remission induction – the first course of chemotherapy aimed at achieving CR.

Remission consolidation – post-remission therapy aimed at "deepening" remission, i.e., further reduction of the tumor population. Patients not eligible for allogeneic hematopoietic stem cell transplantation (allo-HSCT) typically receive 3–4 courses of therapy based on intermediate/high doses of cytarabine**.

Maintenance therapy – continuation of chemotherapy after the completion of the intensive phase of the protocol, aimed at the gradual elimination of the residual stem cell pool of the tumor clone. Antimetabolites (6-mercaptopurine and cytarabine**), critical signaling pathway inhibitors (FLT-3 inhibitors), and epigenetic drugs are used as maintenance therapy.

Prophylaxis or, if necessary, treatment of neuroleukemia neuroleukemia – this stage is distributed across all periods of program treatment: remission induction, consolidation, and maintenance therapy.

Hematopoietic stem cell transplantation – this term encompasses transplantation of hematopoietic stem cells from bone marrow, peripheral blood, and umbilical cord (placental) blood.

Standard definitions for infectious complications:

Neutropenia – a granulocyte count of less than 0.5×10⁹/L, or less than 1.0×10⁹/L with an expected decline over the next few days.

Febrile episode – a single elevation of body temperature $\ge$38.3°C or a body temperature $\ge$37.8°C lasting for one hour or more [109, 110].

Hypothermia – a drop in body temperature below 36°C. This indicator is an important sign of an infectious process, especially in young children and patients receiving glucocorticosteroids [111, 112].

Fever of unknown origin – a condition characterized by a febrile episode in the absence of clinical and radiological manifestations of infection and microbiological data.

Bacteremia – identification of a microorganism from a blood culture taken during a febrile episode that is not a contaminant. False bacteremia includes the identification of so-called contaminating microorganisms – skin commensals: coagulase-negative staphylococci, Propionibacterium spp., Micrococcus spp., etc. – in the event of their single identification [106, 110, 113, 114].

Proven infection is defined as one with the identification of a microorganism from sterile body substrates (blood, cerebrospinal fluid, urine, biopsy material) in the presence of inflammatory response symptoms, or the isolation of a pathogen from non-sterile substrates (skin, mucous membranes, gastrointestinal tract) with a corresponding local clinical presentation of infection.

Probable infection is an infection without microorganism identification from the studied media in the presence of clinical and/or radiological signs of infection with a rapid response to anti-infective therapy.

Febrile neutropenia (FN) is a symptom complex combining the development of fever or hypothermia in a patient with criteria for neutropenia. It is the most anticipated infectious complication and develops in the vast majority of high-risk patients.

The high-risk group includes patients with AML throughout the entire period of chemotherapy, and hematopoietic stem cell transplantation (HSCT) recipients.

In patients with neutropenia, due to impaired barrier function of the gastrointestinal mucosa, the phenomenon of endogenous intestinal flora translocation directly into the bloodstream may develop. During an infectious episode, local clinical symptoms may be absent, and the only sign may be febrile fever/hypothermia, lethargy, or altered mental status.

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Acute myeloid leukemia is a clonal neoplastic disease of the hematopoietic tissue associated with a mutation in a hematopoietic progenitor cell, resulting in a differentiation block and uncontrolled proliferation of immature myeloid cells [1].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

AML is a consequence of damage — a mutation — in the genetic material of the clonogenic hematopoietic cell apparatus. As a result of this mutation, cell cycle control is impaired, along with changes in the transcription process and the production of a number of key proteins. Due to uncontrolled proliferation in the absence of differentiation, pathological cells accumulate. The fact that the pathogenesis of acute leukemias is associated with genetic lesions is quite often confirmed by the detection of various chromosomal aberrations (translocations, deletions, inversions, etc.). In most cases, the specific cause of AML remains unknown. However, there are several predisposing factors that significantly increase the risk of developing this disease. A clearly proven relationship between ionizing radiation from an atomic bomb explosion, as well as chemo- and radiotherapy for other malignant neoplasms and an increased risk of acute leukemias, has prompted the study of other potential leukemogenic factors (low doses of radiation, chemicals, smoking, electromagnetic waves). It has been proven that there is a dose-dependent relationship between smoking and the risk of developing acute leukemia, which is especially evident in individuals over 60 years of age. A number of researchers suggest that about 20% of AML cases are a consequence of smoking. Benzene, with prolonged exposure to the human body, has a carcinogenic effect and a leukemogenic effect, but at the low concentrations of this substance most commonly encountered by people in the workplace, a relationship with an increased risk of AML has not been proven. Studies on the continuous exposure of low doses of radiation have not yet yielded evidence supporting an increased incidence of AML. The relationship between prior chemotherapy (CT), radiation therapy for other tumor diseases, and an increased risk of AML was first noted in patients cured of Hodgkin lymphoma. It has been proven that it is not so much the cumulative dose, but rather the intensity of dose exposure that causes an increase in the incidence of AML. The risk of secondary AML is highest between 2 and 9 years after the completion of prior CT. In 85% of cases, secondary leukemias occur within 10 years of the end of treatment [3,4]. The etiology and specific factors leading to the development of secondary AML are not fully understood. Many genetic pathways and cooperative mutations are involved in the pathogenesis. "Secondary" AML associated with the use of alkylating agents often presents as myelodysplastic syndrome (MDS) with monosomy or partial deletion of chromosomes 5 and 7. This type of AML occurs relatively late, on average 5–7 years after patients are cured of the primary malignancy.

The probability of developing leukemias increases in the following genetically determined conditions: congenital agammaglobulinemia, Shwachman-Diamond syndrome, ataxia-telangiectasia, Li-Fraumeni syndrome, neurofibromatosis, Diamond-Blackfan anemia, severe congenital neutropenia, Fanconi anemia, Down syndrome, and Bloom syndrome.

1.3 Epidemiology of the Disease or Condition

It is estimated that AML affects an average of 3–5 per 100,000 population per year. Furthermore, the incidence increases sharply in individuals older than 60 years, reaching 12–13 per 100,000 in people over 80. The median age for this disease is 65 years. The epidemiology of AML among the pediatric population in the Russian Federation has not been sufficiently studied. Acute myeloid leukemia accounts for 20% of all acute leukemias in children and 6% of all pediatric tumors. New cases of AML in children range from 0.7 to 1.2 per 100,000 per year [1,5].

1.4 Features of Coding the Disease or Condition

C92.0 Acute myeloid leukemia

Exclusion: accelerated phase / blast crisis of chronic myeloid leukemia (C92.1)

C92.3 Myeloid sarcoma (chloroma, granulocytic sarcoma)

C92.5 Acute myelomonocytic leukemia

C92.6 Acute myeloid leukemia with 11q23 abnormality

C92.7 Other myeloid leukemia

C92.8 Acute myeloid leukemia with multilineage dysplasia

C92.9 Myeloid leukemia, unspecified

C93.0 Acute monoblastic/monocytic leukemia

C94.0 Acute erythroid leukemia (erythremia and erythroleukemia)

C94.2 Acute megakaryoblastic leukemia

1.5 Classification of the disease or condition

List of AML variants and other tumors with myeloid differentiation (WHO, 2016) [6,7]:

The WHO classification (2016) subdivides all AML cases based on their cytogenetic and molecular genetic features (more details in Appendix A3.4), and it is these features that form the clinical and pathological groups:

AML with recurrent genetic abnormalities

AML with t(8;21)(q22;q22); RUNX1-RUNX1T1

AML with inv(16)(p13.1q22) or t(16;16)(p13.1;q22); CBFB-MYH11

APL with t(15;17)(q22;q12); PML-RARA

AML with t(9;11)(p22;q23); MLLT3-MLL

AML with t(6;9)(p23;q34); DEK-NUP214

AML with inv(3)(q21q26.2) or t(3;3)(q21;q26.2); RPN1-EVI1

AML (megakaryoblastic) with t(1;22)(p13;q13); RBM15-MKL1

AML with BCR/ABL1*

AML with gene mutations*:

AML with mutated NPM1 gene*

AML with biallelic mutations of the CEBPA gene*

AML with mutated RUNX1 gene*

AML with myelodysplasia-related changes

Therapy-related myeloid neoplasms

AML, not otherwise specified (NOS)

Acute myeloblastic leukemia with minimal differentiation

Acute myeloblastic leukemia without maturation

Acute myeloblastic leukemia with maturation

Acute myelomonocytic leukemia

Acute monoblastic/monocytic leukemia

Acute erythroid leukemia

Acute megakaryoblastic leukemia

Acute basophilic leukemia

Acute panmyelosis with myelofibrosis (syn.: acute myelofibrosis; acute myelosclerosis)

Myeloid sarcoma (syn.: extramedullary myeloid tumor; granulocytic sarcoma; chloroma)

Myeloid proliferations related to Down syndrome

Transient abnormal myelopoiesis (syn.: TAM)

Myeloid leukemia associated with Down syndrome

Plasmacytoid dendritic cell neoplasm

Acute leukemias of ambiguous lineage

Acute undifferentiated leukemia

Mixed phenotype acute leukemia (MPAL) with t(9;22)(q34;q11.2); BCR-ABL1

Acute mixed phenotype leukemia with t(v;11q23.3); KMT2A gene rearrangement (formerly MLL)

Mixed phenotype acute leukemia, B/myeloid, NOS

Mixed phenotype acute leukemia, T/myeloid, NOS

Mixed phenotype acute leukemia NOS*

Acute leukemias of ambiguous lineage NOS*

* new categories introduced into the WHO classification in 2016

The subgroup "AML with recurrent cytogenetic abnormalities" combines several AML variants:

"AML with t(8;21)(q22;q22); RUNX1-RUNX1T1"

"AML with inv(16)(p13.1q22) or t(16;16)(p13.1;q22); CBFB-MYH11" (when these chromosomal rearrangements are detected, acute myeloid leukemia is diagnosed regardless of the blast cell count in the bone marrow aspirate).

"APL with t(15;17)(q22;q12); PML-RARA"; RARA translocations with other partners are classified as separate AML entities, for example: AML with t(11;17)(q23;q12); ZBTB16-RARA; AML with t(11;17)(q13; q12); NUMA1-RARA; AML with t(5;17)(q35;q12); NPM1-RARA; AML with STAT5BRARA.

The previously recognized category "AML with 11q23 abnormalities (MLL)" has been revised to "AML with t(9;11)(p22;q23); MLLT3-MLL"; other translocations involving partners distinct from MLLT3 must be specifically stated in the diagnosis, for instance, AML with t(6;11)(q27;q23); MLLT4-MLL; AML with t(11;19)(q23;p13.3); MLLMLLT1; AML with t(11;19)(q23;p13.1); MLL-ELL; AML with t(10;11)(p12;q23); MLLT10- MLL

Three new subgroups have been defined: "AML with t(6;9)(p23;q34); DEK-NUP214", "AML with inv(3)(q21q26.2) or t(3;3)(q21; q26.2); RPN1-EVI1", and "AML (megakaryoblastic) with t(1;22)(p13;q13); RBM15-MKL1", a rare variant of acute leukemia most frequently diagnosed in children.

Two new categories were established for patients with AML and a normal karyotype: "AML with mutated NPM1 gene (nucleophosmin [nuclear phosphoprotein B23, numatrin])" and "AML with mutated CEBPA gene (CCAAT/enhancer-binding protein alpha)". Growing evidence indicates that these mutations drive hematopoietic differentiation defects and belong to the so-called class 2 mutations.

Mutations in the fms-related tyrosine kinase 3 (FLT3) gene are detected in many AML variants and are classified as class 1 mutations, i.e., those that confer a proliferative and/or survival advantage to tumor cells. AML with FLT3 mutations is not recognized as a separate category, but testing for these mutations is essential due to their prognostic significance. It is recommended to determine not only the presence of FLT3-ITD, but also the so-called allelic ratio, which reflects the tumor burden. An allelic ratio is considered high when it is $\ge$ 0.5 and low when it is < 0.5. High values have prognostic significance.

The previously recognized subgroup "AML with multilineage dysplasia" in the WHO classification (2016) is defined as "AML with myelodysplasia-related changes". AML cases may be classified under "AML with myelodysplasia-related changes" if:

1) $\ge$ 20% blast cells in the bone marrow or peripheral blood

2) there is a prior history of MDS or another myeloproliferative neoplasm (MPN);

3) cytogenetic abnormalities associated with myelodysplasia are present:

a - complex karyotype (3 or more chromosomal abnormalities);

b - unbalanced rearrangements: -7 or del(7q); -5 or del(5q); i(17q) or t(17p); -13 or del(13q); del(11q); del(12p) or t(12p); del(9q); idic(X)(q13);

c - balanced rearrangements (translocations): t(11;16)(q23;p13.3); t(3;21)(q26.2;q22.1); t(1;3)(p36.3; q21.1); t(2;11)(p21;q23); t(5;12)(q33;p12); t(5;7)(q33;q11.2); t(5;17)(q33;p13); t(5;10)(q33;q21); t(3;5)(q25;q34).

4) multilineage dysplasia;

5) "recurring genetic abnormalities" are absent;

6) no prior chemotherapy for another disease.

AML and other myeloid neoplasms arising as a result of prior chemotherapy for other diseases are not classified as a separate AML entity.

Prognostic factors

In children, they are driven by the biological characteristics of the leukemic clone

Disease-related prognostic factors (AML)

Disease-related factors influencing treatment outcomes should be evaluated at all stages of therapy. This is because leukemia-associated prognostic factors allow for the assessment of tumor burden, the sensitivity of blast cells to cytotoxic drugs, the rate of leukemic cell clearance, and measurable residual disease (MRD) levels.

First and foremost, readily available clinical and hematological parameters associated with an unfavorable AML course must be taken into account, such as leukocytosis above 100$\times$10⁹/L, and failure to achieve complete remission (CR) after the first induction course.

One of the most critical prognostic factors in AML is the karyotype of the leukemic cells. Karyotyping is mandatory for all patients with suspected AML. Cytogenetic data allow for the verification of AML in cases where the presence of specific chromosomal aberrations is more critical than the absolute blast count (less than or greater than 20%). This refers, in particular, to the so-called CBF (Core Binding Factor) AML, which encompasses cases with t(8;21) and inv(16) translocations, regardless of the presence or absence of additional chromosomal aberrations.

In addition, karyotype analysis makes it possible to stratify AML patients into 3 main risk groups: favorable, intermediate, and unfavorable prognosis (see Appendix A3.5.). Stratifying AML patients into these groups is essential for selecting post-remission therapy tactics: high-dose cytarabine** (HDAC), and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recently, several Russian and American experts have advised against standard chemotherapy for patients with unfavorable karyotypic abnormalities due to its low efficacy, recommending alternative low-dose regimens and the inclusion of targeted therapies starting from the first induction cycle [8].

It should be noted that a normal leukemic cell karyotype is detected in half of AML patients. Because some patients present with a normal karyotype, FISH or molecular genetic testing is necessary to search for specific chimeric genes or chromosomal breaks associated with particular AML variants: RUNX1-RUNX1T1 (t(8;21)), CBFB-MYH11 (inv16), PML-RARa (t(15;17)), MLLT3-MLL (t(9;11)), DEK-NUP214, monosomies 5 and 7, chromosome 3 inversions, and several others.

Chemotherapy-related prognostic factors

An adverse prognostic factor is the reduction of calculated cytotoxic drug doses and significant lengthening of intervals between cycles [3].

Modern AML treatment is impossible without comprehensive baseline diagnostics performed at the onset of the disease.

Infectious complications are the main cause of morbidity and mortality in AML patients during chemotherapy and HSCT; their development leads to dose reductions and delays in chemotherapy timing [105-107]. Infections caused by antibiotic-resistant microorganisms lead to life-threatening complications due to extremely limited therapeutic options [108]. Proper and rational prescription of antibacterial and antifungal therapy is a significant prognostic factor in the management of AML patients.

If these requirements cannot be met, the transfer (routing) of the child to a medical facility where these conditions can be fully met must be considered.

1.6 Clinical presentation of the disease or condition

Clinical manifestations are primarily associated with the replacement of normal hematopoietic tissue by tumor cells (anemia, thrombocytopenia, granulocytopenia), infiltration of various organs, and cytokine production [9]. The onset of AML can be acute, accompanied by a significant fever, severe weakness, intoxication, bleeding tendencies, and severe infections. However, the diagnosis is sometimes established during routine health screenings (dispensary checks) or upon hospitalization for another reason.

No symptoms may be observed upon physical examination. However, peripheral lymphadenopathy, hepatosplenomegaly (most characteristic of mono- and myelomonoblastic leukemia), gingival hyperplasia (in myelomonocytic and monoblastic variants), skin infiltration (in myelomonocytic and monoblastic variants), hemorrhagic syndrome of varying severity—from petechial rashes to severe bleeding, bone pain, arthralgia, and neurological symptoms (meningeal signs: headache, nuchal rigidity, Kernig's sign, facial, oculomotor and other nerve paresis, lower limb paresis, etc.) are quite frequently detected. Blood tests may show non-specific changes: three-lineage cytopenia, or anemia, or isolated leukopenia, leukocytosis, or thrombocytopenia. Blast cells may be undetectable in the peripheral blood smear or, conversely, account for 90–95% of all leukocytes. The leukocyte count also varies from less than 1.0 to 200–300 × 10⁹/L or more. In approximately 15% of cases, leukocytosis exceeding 100 × 10⁹/L is detected at disease onset.

Differential diagnosis: if pathological blast cells are detected in a bone marrow aspirate and/or in the peripheral blood, the diagnosis is unquestionable. The absence of blast cells in the peripheral blood does not rule out AML. An elevated leukocyte count with a left shift in various infectious processes, as well as thrombocytopenia, anemia, and hemorrhagic syndrome in severe infections and sepsis, may raise doubt regarding the diagnosis of AML, but pathological blast cells are never found in such cases. Differential diagnosis is often required with infectious mononucleosis and certain other viral infections, especially since the clinical symptoms (fever, sore throat, enlargement of lymph nodes, liver, spleen) may resemble those of AML. The differential diagnosis should be carried out with the following conditions: other acute leukemias: acute lymphoblastic leukemia, mixed-phenotype acute leukemia, myelodysplastic syndrome, juvenile myelomonocytic leukemia, leukemoid reactions, aplastic anemia; non-hematopoietic malignancies (neuroblastoma, sarcomas, etc.), especially in the presence of extramedullary lesions, and blast crisis of chronic myeloid leukemia (the presence of the Philadelphia chromosome may also be detected in newly diagnosed AL).

Extramedullary manifestations of AL deserve special attention, particularly neuroleukemia, which can also be identified at the time of AL diagnosis. The development of neuroleukemia is caused by the spread of leukemic cells into the meninges of the brain and spinal cord. In some cases, leukemic infiltration of peripheral nerves with various motor and sensory impairments is observed, or focal brain tissue lesions are detected. Neuroleukemia is characterized by meningeal and hypertensive syndromes: persistent headache, possible vomiting, lethargy, papilledema, nystagmus, strabismus, other signs of cranial nerve involvement, nuchal rigidity, and Kernig's sign are noted. In AML, neuroleukemia is quite rare at disease onset; nevertheless, it occurs in myelomonocytic and monoblastic variants, especially in those forms of leukemia associated with chromosome 16 breakage – inv(16) (neuroleukemia develops in 30% of such patients in the absence of prophylaxis). Extramedullary lesions in AML include skin involvement (leukemids – most commonly purplish-bluish skin thickenings and nodules), retinal, gingival, testicular, and ovarian involvement. Involvement of lymph nodes, lungs, intestines, myocardium, and ureters has been described. In AML, extramedullary soft tissue lesions were previously referred to as «chloroma». Currently, the terms myeloid sarcoma or granulocytic sarcoma are used to designate soft tissue and organ involvement.

2. Diagnostics, medical indications and contraindications for diagnostic methods

Many recommended methods for diagnosing the disease and related conditions have a limited evidence base according to the scales for assessing the levels of reliability of evidence (LRE) and levels of concordance of recommendations (LCR) due to the lack of dedicated clinical studies. Despite this, they are necessary elements of patient evaluation to establish a diagnosis and select treatment tactics, as more effective and proven methods have not yet been developed.

Criteria for establishing the diagnosis/condition: the diagnosis of AML is established based on the detection of at least 20% blast cells in the bone marrow aspirate or peripheral blood, or regardless of the percentage of blast cells if pathognomonic morphological features of AML (Auer rods) and chromosomal abnormalities are present: t(8;21) (q22; q22) AML/ETO, t(15;17) (q12; q11-12) PML/RAR-α, inv(16) or t(16;16) (p12; q23) CBF/MYH11, t(1;22)...

A summary table of tests required for the diagnosis and verification of AML is presented in Appendix A3.1. Based on the clinical picture and the analysis of the results of the listed tests, patients are stratified into molecular genetic (see Appendix A3.5) and clinical prognostic groups.

2.1 Complaints and Anamnesis

Clinical manifestations in AML are typically associated with hemogram abnormalities, namely cytopenia:

Neutropenia – bacterial infections, generally manifesting as fever;

Anemia – weakness, fatigue. General weakness is present in the majority of patients;

Thrombocytopenia – hemorrhagic syndrome in the form of petechiae, gingival bleeding, epistaxis, menorrhagia, and metrorrhagia.

In some cases, ossalgia and B symptoms (fever, weight loss, profuse sweating) may be observed.

2.2 Physical Examination

Comments: upon physical examination, a portion of patients (primarily those with acute myelomonoblastic leukemia and acute monoblastic leukemia) exhibit signs of «proliferative» syndrome—splenomegaly, lymphadenopathy, and cutaneous leukemids. Leukemids are detected in 13% of cases and appear as nodules with altered skin color overlying them [12]. Myeloid sarcoma presents as extramedullary tumor formations of various localizations [13]. Otherwise, manifestations are non-specific and include symptoms associated with cytopenia.

2.3 Laboratory Diagnostics

Comments: typically, normochromic, normocytic anemia of varying severity is detected at the onset of AML. The reticulocyte count is within normal limits or decreased. Approximately 75% of patients have thrombocytopenia. The mean leukocyte count at the stage of diagnosis establishment is about 15 × 10⁹/L. Leukocytosis exceeding 100 × 10⁹/L is recorded in 20% of patients.

When indicated, the leukocyte differential count must be performed manually rather than on an automated analyzer. It is recommended to examine at least 200 leukocytes in the peripheral blood smear.

• It is recommended that all patients with suspected or established AML, as well as during therapy, undergo a general (clinical) urinalysis with a frequency ranging from weekly to monthly (as clinically indicated) to diagnose concurrent pathologies and determine supportive care tactics [14,16].

• Level of Recommendation C (Level of Evidence – 5)

Comments: blood cultures for sterility must be performed before prescribing antibiotics. Blood is drawn from a peripherally inserted central catheter (PICC) or, if unavailable, from a peripheral vein during a febrile spike, episode of hypothermia, chills, and/or hemodynamic instability, or the appearance of septicopyemic foci. If the patient has a multi-lumen central venous catheter and catheter-related bloodstream infection is suspected, blood samples must be drawn from each lumen. Reliable results are achieved by properly selecting blood culture bottles and matching the volume of blood collected: for children up to 10–12 kg, 1–3 ml into pediatric bottles; for children over three years old, 6–10 ml into aerobic bottles (it is optimal to use an automated blood culture analyzer). For a suspected anaerobic etiology of the infection, use anaerobic bottles; for a suspected fungal infection, use mycotic bottles. To prevent contamination and misinterpretation, strict adherence to aseptic technique during blood collection is mandatory. To increase test sensitivity, drawing blood two to three times during the first 24 hours of fever is indicated. Following microorganism verification, further blood tests should be performed 24–48 hours after initiating antibacterial therapy and continued until the first negative result is obtained. Repeat blood cultures are necessary if FN persists for 72 hours, as well as prior to escalating antibacterial therapy [114 - 117].

Comment: given the increasing frequency of antibiotic resistance, it is necessary to determine susceptibility to antimicrobial drugs, including reserve-group agents, and to identify resistance determinants.

Comments: microbiological testing is performed to guide precision antibiotic therapy during treatment in the presence of febrile neutropenia and infectious complications.

Comments: obtaining a bone marrow cytological specimen via puncture is a mandatory routine diagnostic procedure. The procedure must be performed under anesthesia (with the consent of the child's legal representative and/or the child aged 15 years or older)!

Bone marrow smears are examined using May-Grünwald, Pappenheim, or Wright-Giemsa staining. Trephine biopsy is not mandatory, except in situations with a so-called "dry tap" or very scant bone marrow aspirate. At least 500 nucleated cells in the bone marrow smear should be examined.

To establish a diagnosis of AML, the presence of 20% or more blast cells in the peripheral blood or bone marrow smear is required. In AML with t(15;17), t(8;21), inv(16), or t(16;16), and in certain cases of acute erythroid leukemia, the proportion of blast cells may be less than 20%. In accordance with the 2016 WHO classification, the percentage of blast cells is calculated regardless of the proportion of the erythroid lineage.

Myeloblasts, monoblasts, and megakaryoblasts are included in the total blast cell count. In cases of AML with monocytic, monoblastic, and myelomonocytic differentiation, promonocytes (but not atypical/mature monocytes) are also counted as equivalents of blast cells. Erythroblasts are not included in the total blast cell count.

To verify the diagnosis of true erythroleukemia, when counting bone marrow aspirate, erythroid cells must account for >80% of all bone marrow cells, with proerythroblasts being >30%, excluding myeloblasts. According to the WHO nomenclature, proerythroblasts are immature erythrokaryocytes, whereas according to the terminology of erythropoiesis cells by I.A. Kassirsky and G.A. Alekseev, they are erythroblasts and pronormoblasts. In true erythroleukemia, dysmegakaryocytopoiesis is frequent, while dysgranulocytopoiesis is rare [26].

Performing a cytochemical study of a bone marrow smear is necessary even if a high blast cell count is detected in the peripheral blood. This is because in some cases, cytochemical reactions may yield different results in peripheral blood and bone marrow cells, which could lead to an erroneous diagnosis. The diagnosis is based on the results obtained from bone marrow cells. Reactions for myeloperoxidase (MPO) or Sudan black, non-specific esterase (alpha-naphthyl acetate esterase, inhibited or not by sodium fluoride), and PAS (Periodic Acid Schiff) are used. The detection of myeloperoxidase in 3% or more of blast cells indicates a myeloid lineage of differentiation. At the same time, its absence does not exclude the myeloid orientation of the cells, because in early myeloblasts, as well as monoblasts, megakaryoblasts, and erythroblasts, MPO is <3% or undetectable. Sudan black staining is similar to MPO, but is less specific. Non-specific esterase has high diffuse or granular cytoplasmic activity (depending on the assay method) in monoblasts and promonocytes, which must be completely or significantly inhibited by sodium fluoride. The PAS reaction is detected in a diffuse pattern in myeloblasts, in a diffuse-granular pattern in monoblasts and promonocytes, and as granules or blocks in erythroblasts. Based on a morphocytochemical study of blast cells, about 90% of AML cases can be diagnosed; if MPO and non-specific esterase activities are absent, an immunophenotyping study using flow cytometry must be performed.

Comments: IPT is always performed on bone marrow cells, even if a high blast cell count is detected in the peripheral blood. Determining the percentage of blast cells by flow cytometry during initial diagnosis does not replace morphological counting, as the results of these two studies may not match [27].

To confirm the myeloid orientation of tumor cells, it is necessary to assess the expression of myeloid antigens. MPO is a lineage-specific marker of the myeloid lineage, a lysosomal enzyme of granulocytes. Less specific myeloid-associated antigens include CD11b, CD11c, CD13, CD15, CD16, CD33, CD64, CD65, CD66b, lysozyme, and others. A diagnosis of AML can also be established if MPO is not detected, provided the tumor cells express other, less specific myeloid markers and the lymphoblastic variant of AL is excluded.

There is no clear correlation between the FAB morphocytochemical classification and immunophenotypic features. Most myeloid markers can be either positive or negative across different FAB variants of AML, with the exception of specific antigens CD41a and CD61, which are characteristic only of the megakaryocytic/platelet lineage. Even glycophorin A (CD235a), an erythroid lineage marker, can be negative in erythroleukemia if the tumor cells originate from earlier precursors. Thus, the FAB variant of AML cannot be determined based on IPT data.

Blast cells are considered positive for the expression of a membrane antigen if it is detected on 20% or more of the blast cells (cutoff value). For cytoplasmic markers (such as cytoplasmic CD3, MPO, lysozyme, nuclear TdT, and others), a lower cutoff of 10% is used.

If a bone marrow aspirate cannot be obtained, immunohistochemical examination of a bone marrow trephine biopsy is performed.

Flow cytometry (FCM) is performed using multiparametric flow cytometry (typically at least 3- or 4-color). In the case of trephine biopsy analysis, immunohistochemical (IHC) examination is performed. FCM is particularly essential for establishing the diagnosis of AML with minimal differentiation, acute megakaryoblastic leukemia, and acute leukemia of ambiguous lineage.

Comments: Standard cytogenetic analysis is an essential component of diagnostic procedures in patients with suspected acute leukemia. Chromosomal abnormalities are detected in approximately half of AML patients. Seven translocations and inversions (and their variants) are classified by the WHO into the category of "AML with recurrent genetic abnormalities". Moreover, the detection of certain genetic abnormalities in the presence of 20% or more blast cells in the bone marrow is sufficient to establish the diagnosis of "AML with myelodysplasia-related changes". For karyotype determination, analysis of at least 20 metaphases is considered reliable. Karyotype abnormalities can also be established based on the examination of peripheral blood cells. Monitoring of karyotype abnormalities identified during the initial study allows for the assessment of the completeness of the achieved therapeutic effect. The identification of certain cytogenetic abnormalities at the time of acute leukemia diagnosis can determine the therapeutic strategy for a specific patient: for example, the detection of complex karyotype changes or a monosomal karyotype indicates the need for a cytostatic regimen different from standard therapy and the mandatory discussion of the possibility of early allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the treatment program, up to performing allo-HSCT during aplasia after the first induction course (based on a multidisciplinary team decision).

Comments: Testing for NPM1, CEBPA, and FLT3 mutations is desirable, as modern approaches to AML treatment require information about these mutations, which can influence the choice of therapeutic strategy. AML with mutations in the NPM1 or CEBPA genes are defined by the WHO as provisional entities. The expression of ERG, MN1, EVI1, BAALC genes, mutations in WT1, RUNX1, MLL, KIT, RAS, TP53, TET2, IDH1 genes, and MRD assessment are investigated within clinical trials. Molecular screening for the specified markers has no independent significance, but as an auxiliary method, it can be used in the absence of standard cytogenetic results. In modern molecular diagnostics of AML, next-generation sequencing (NGS) is also widely used; so-called diagnostic panels consisting of several dozen genes involved in AML pathogenesis have been developed, allowing for the precise classification of the studied AML into a specific risk category.

Comments: in AML, RUNX1-RUNX1T1, CBFB-MYH11, PML/RARA, MLL and EVI1, or loss of chromosome 5q and 7 are investigated. FISH is often necessary to identify MLL fusions in 11q23 region translocations. FISH can also be performed on bone marrow morphology and histology specimens.

Comments: to confirm the completeness of the achieved response to therapy and its maintenance, in accordance with current international guidelines, MRD assessment by flow cytometry (aberrant immunophenotype) should be performed at control time points, while for the favorable-risk group, only molecular MRD testing by PCR (quantitative assessment of RUNX1-RUNX1T1, CBFB-MYH1, NPM1 gene expression)  [29,30].

According to the results of studies conducted by the Russian Acute Leukemia Working Group, if an MRD-negative remission is achieved after the 1st course of therapy in patients from the intermediate-risk group, with subsequent rigorous MRD monitoring, the continuation of chemotherapy without allogeneic hematopoietic stem cell transplantation (allo-HSCT) may be considered. In patients from the favorable-risk group, the kinetics of the chimeric transcript also determines the indication for allo-HSCT [31].

Comments: in AML overall, CNS involvement occurs in less than 5% of patients; in certain AML variants, especially those with monocytic differentiation, the probability of leptomeningeal involvement is higher.

It is advisable to maintain a peripheral blood platelet count of 30×10⁹/L or higher prior to lumbar puncture. If the platelet count cannot be raised to 30×10⁹/L or higher, in the absence of clinical signs of CNS involvement, the puncture may be deferred until the blood platelet count rises above 30×10⁹/L.

If a patient has a blood leukocytosis exceeding 100×10⁹/L, the first lumbar puncture should be postponed until the leukocyte count drops below 20×10⁹/L.

Comments: primary biological material is preserved as DNA and/or RNA isolated from bone marrow cells or as frozen cells. This material may subsequently be required for molecular assays to determine risk groups, as well as within clinical trials (CT).

2.4 Instrumental Diagnostics

• It is recommended that all patients with AML undergo unenhanced computed tomography (CT) of the brain before starting targeted therapy, as indicated by comorbid conditions and the clinical situation, as well as when clinically indicated at any time throughout the treatment period, to detect and/or monitor structural changes in the brain [1,3,4,8,33–35].

• Level of evidence C (confidence level of evidence – 5) 

Comment: A chest CT must be performed if refractory febrile neutropenia develops, even in the absence of any clinical respiratory symptoms. If signs of pneumonia are detected, tracheobronchoscopy and bronchoalveolar lavage (BAL) should be performed. The scope of the study should be maximized and, if necessary, include: microscopic, microbiological, mycological, and molecular biological studies in accordance with Appendix 3.6. The highest diagnostic value will be obtained from BAL results performed before the initiation of anti-infective therapy [125–127].

It should be remembered that plain chest X-ray in neutropenic patients has low diagnostic utility and is indicated only for the diagnosis of complications such as pneumothorax, pleural effusion, hydropericardium, as well as for checking the position of central venous catheters, pleural drains, or endotracheal tubes [124, 128, 129].

Comments: the scope and area of the study are determined by the clinical presentation.

Comment: depending on the clinical situation, a comprehensive ultrasound of internal organs, echocardiography (to rule out endocarditis), duplex scanning of the upper extremity veins in the projection of the central venous catheter (CVC) (to rule out CVC-associated thrombotic deposits), CT or MRI of the abdominal cavity, retroperitoneal space, and pelvis with contrast (to rule out internal organ and bowel involvement), esophagogastroduodenoscopy, and colonoscopy (to rule out erosive and ulcerative processes, or pathological infiltration) are performed.

2.5 Other Procedures

Comment: galactomannan assay in the blood may be performed exclusively in neutropenic patients not receiving systemic antifungal prophylaxis active against molds, at a frequency of twice a week.

Comment: If bronchoscopy is not feasible, galactomannan testing in a neutropenic patient should be performed in blood serum.

Comment: other methods, including DNA detection and microscopy, can also be used to detect Cryptococcus. Due to the nonspecific clinical and radiological presentation, the diagnostic workup should include, in addition to central nervous system cryptococcal infection, invasive mycoses, toxoplasmosis, listeriosis, herpesvirus infection, and mycobacteriosis, including atypical ones.

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

The efficacy of chemotherapy for myeloid leukemia depends on two key factors: the specificity of the cytostatic effect and the adequacy of supportive care. The main treatment principles for acute leukemia are maximum efficacy (achieved through specificity and adequacy of impact) combined with minimum toxicity (achieved through competent supportive therapy).

Treatment of AML in children is based on intensive polychemotherapy, which must be supplemented by allogeneic hematopoietic stem cell transplantation (allo-HSCT) from an HLA-genoidentical related or alternative (unrelated, haploidentical) donor in patients at high risk of relapse. The necessity of transplantation in intermediate-risk patients remains under discussion and is indicated only in the presence of an HLA-genoidentical sibling.

Due to the intensity of the specific and supportive therapy administered, the patient requires catheterization of the subclavian and other central veins using a tunneled or double-lumen cuffed catheter prior to treatment initiation.

3.1 Treatment of newly diagnosed AML

Comments: currently, there is no single standardized treatment regimen for AML in children. Without specific chemotherapy, all patients with AML die within 2-3 months.

Comments: treatment begins with a remission induction course consisting of core drugs effective against AML (cytarabine**, anthracyclines, and etoposide**). Once remission is achieved and hematopoiesis recovers, a short consolidation therapy (no more than 3 courses) is administered, based on high-dose cytarabine** 2000–3000 mg/m² every 12 hours.

If an HLA-compatible related donor is available, all high-risk patients should undergo transplantation in their first remission after three blocks of consolidation therapy. High-risk patients must receive a transplant from an HLA-compatible related or unrelated donor, or from an alternative (haploidentical) donor.

Allogeneic HSCT is performed only in specialized centers, where patient information must be sent in advance. An application for HSCT should be submitted to the transplantation center immediately upon establishing that the patient is at high risk or has an HLA-identical related donor.

1. AIE (Cytarabine**, #Idarubicin**, Etoposide**) [68, 181, 182]

Cytarabine** 100 mg/m2 per day on days 1–2 as a continuous infusion

Cytarabine** 100 mg/m2 as a 30-minute infusion every 12 hours on days 3–8 as a continuous infusion

#Idarubicin** 12 mg/m2 per day as a 4-hour infusion for 3 days (depending on the prescribed treatment protocol)

#Etoposide** 150 mg/m2 as a 1-hour infusion on days 6, 7, 8

GCR BLEL 2Grade of Recommendations B (Level of Evidence – 2)

2. AM42E (Cytarabine**, #Mitoxantrone**, Etoposide**) [182]

Cytarabine** 100 mg/m2 as a 1-hour infusion every 12 hours on days 1–7

#Mitoxantrone** 14 mg/m2 per day as a 1-hour infusion on days 2, 3, 4 (3 doses in total)

#Etoposide** 100 mg/m2 as a 1-hour infusion on days 5, 6, 7 (3 doses in total)

GDR CLE 5Grade of recommendation C (level of evidence – 5)

3. AM36E (Cytarabine**, #Mitoxantrone**, Etoposide**) – for AML patients with inv(16) [182]

Cytarabine** 100 mg/m² as a 1-hour infusion every 12 hours on days 1–7

#Mitoxantrone** 12 mg/m² per day as a 1-hour infusion on days 2, 3, 4 (3 doses in total)

#Etoposide** 100 mg/m2 as a 1-hour infusion on days 5, 6, 7 (3 doses in total)

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

4. ADE (Cytarabine**, Daunorubicin**, Etoposide**) (level of evidence 4C) [69]

Cytarabine** 100 mg/m2, IV twice daily on days 1–10, 20 doses total per cycle, then on days 1–8, 16 doses total

Daunorubicin** 50 mg/m2, on days 1, 3, and 5

#Etoposide** 100 mg/m2, on days 1–5

GCR BLEL 2Grade of Recommendations B (Level of Evidence – 2)

5. ADEGO (Cytarabine**, Daunorubicin**, Etoposide**, Gemtuzumab ozogamicin) – for AML patients with inv(16) (CBF::MYH) and t(8;21) (RUNX1::RUNX1T) [104, 181, 182]

Cytarabine** 100 mg/m² as a 1-hour infusion every 12 hours on days 1–10

Daunorubicin** 50 mg/m² per day on days 2, 4, 6

Etoposide** 100 mg/m² per day on days 2–6

Gemtuzumab ozogamicin 3 mg/m² as a 2-hour infusion on day 6

Level of Recommendations CLevel of Evidence 5 Level of recommendation certainty C (level of evidence – 5)

Comments: If an anthracycline is missing, it should be replaced with an available alternative drug at equivalent myelotoxic doses: #idarubicin**:#mitoxantrone** 1:1, #idarubicin**:daunorubicin** 1:5, daunorubicin**:#mitoxantrone** 5:1. When replacing #mitoxantrone** with #idarubicin** in the AM₄₂E cycle, the single dose of #idarubicin** is 12 mg/m2

Consolidation regimens:

Course 1 is administered according to one of the following regimens:

1. HAM 30 [72, 175, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

#Mitoxantrone** 10 mg/m² as a 1-hour infusion on days 2, 3, 4 (3 doses in total)

2.      HAM 20 [96, 175, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3, 6 doses in total

#Mitoxantrone** 10 mg/m² as a 30-minute infusion on days 4, 5, 2 doses in total

3. HA (for AML patients with inv(16)) [74, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

4.      AI [68, 181, 182]

#Cytarabine** 500 mg/m² per day as a 96-hour infusion on days 1, 2, 3, 4

#Idarubicin** 7 mg/m² as a 60-minute infusion on days 3, 5, 2 doses in total

Consolidation course 2 is administered according to one of the following regimens:

1. haM [68, 175, 181, 182]

#Cytarabine** 1000 mg/m² as a 3-hour infusion every 12 hours for 3 days (6 doses in total)

#Mitoxantrone** 10 mg/m² as a 30-minute infusion for 2 days (2 doses in total)

2. AI (for those who received HAM 20 in the cycle) [68, 181, 182]

#Cytarabine** 500 mg/m² per day as a 96-hour infusion on days 1, 2, 3, 4

#Idarubicin** 7 mg/m² as a 60-minute infusion on days 3, 5, 2 doses in total

3. HAE [68, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

#Etoposide 125 mg/m² as a 2-hour infusion on days 2, 3, 4, 5 (4 doses in total)

4. haM₂₄ (for AML patients with inv(16)) [70, 175, 181, 182]

#Cytarabine** 1000 mg/m² as a 2-hour infusion every 12 hours on days 1, 2, 3, 4, 8 doses in total

#Mitoxantrone** 12 mg/m² as a 60-minute infusion on days 3, 4, 2 doses in total

The MidAC regimen is highly toxic for consolidation; the cumulative dose of mitoxantrone in this regimen is 50 mg, which is equivalent to 250 mg of daunorubicin.

5. FLA (for high-risk patients scheduled for HSCT) [99, 103, 181, 182]

#Fludarabine** 30 mg/m² as a 30-minute infusion on days 1, 2, 3, 4, 5, 5 doses in total. The interval between the start of #fludarabine** infusion and the start of cytarabine** infusion must be 4 hours

The FLA regimen can be used both with and without an anthracycline

Cytarabine** 2000 mg/m² as a 3-hour infusion every 24 hours on days 1, 2, 3, 4, 5, 10 doses in total

6. haMGO (for AML patients with inv(16) and t(8;21)) [183]

#Cytarabine** 1000 mg/m² as a 2-hour infusion every 12 hours for 4 days (8 doses in total)

#Mitoxantrone** 12 mg/m² as a 60-minute infusion on days 3–6 (4 doses in total)

Gemtuzumab ozogamicin 3 mg/m² as a 2-hour infusion once on day 7

For patients with inv(16) and t(8;21), the cumulative mitoxantrone dose of 48 mg in post-induction therapy is excessively toxic, so the dose is reduced to 24 mg.

Consolidation course 3 is administered according to one of the following regimens:

1. HAE [68, 97, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

#Etoposide 125 mg/m² as a 2-hour infusion on days 2, 3, 4, 5 (4 doses in total)

2. haM [181]

#Cytarabine** 1000 mg/m² as a 3-hour infusion every 12 hours for 3 days (6 doses in total)

#Mitoxantrone** 10 mg/m² as a 30-minute infusion for 2 days (2 doses in total)

3. HA (for AML patients with inv(16)) [74, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

4.      AI [101, 181, 182]

#Cytarabine** 500 mg/m² as a 2-hour infusion every 12 hours for 4 days (8 doses in total)

#Idarubicin** 7 mg/m² as a 60-minute infusion on days 3 and 5 (2 doses in total)

Consolidation course 4 (if prescribed by the protocol) is administered according to the following regimen:

1. HAE [101, 102, 181, 182]

Cytarabine** 3000 mg/m² as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

#Etoposide** 125 mg/m² as a 1-hour infusion on days 2, 3, 4, and 5 (4 doses in total)

Comments: The order of consolidation cycles can be modified if clinically indicated.

Comments: #Venetoclax** is prescribed as 50 mg and/or 100 mg tablets starting from day 1 of the course, once daily in gradually increasing doses to avoid tumor lysis syndrome, which has been described in patients with CLL. The target daily dose is reached on day 3 of administration (for doses see Table 1). The duration of #venetoclax** administration is 28 days in children for whom induction chemotherapy is not feasible due to a severe somatic condition (severe infection, cerebrovascular accident, mechanical ventilation, renal replacement therapy, acute heart and vascular failure, severe hepatic failure).

To achieve a deeper and higher-quality remission, #venetoclax** is prescribed starting from day 16 of induction for 14 days following the completion of remission induction.

Table 1. Calculation of #venetoclax** dose based on the child's weight

#Venetoclax** dose modification when co-administered with drugs affecting its metabolism.

#Decitabine is administered at a dose of 5 mg/m² on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, and 26 of each cycle subcutaneously. Local anesthesia is recommended using a cream containing a fixed combination of lidocaine + prilocaine applied 2.5 hours before the subcutaneous injection. Administration of the first 6 doses of #decitabine is mandatory. If hematopoietic aplasia develops by day 15, along with febrile episodes and complete blast clearance, the subsequent 6 administrations may be omitted. #Venetoclax** is continued for all 28 days of the cycle [84, 86, 98].

Comments: #Valproic acid** in the treatment of AML patients is used as a DNA-demethylating agent via histone deacetylase inhibition. It is prescribed from the first day of chemotherapy throughout the entire course of therapy at a dose of 50 mg/kg daily per os.

#Tretinoin** in combination with #valproic acid** potentiates the effect of the latter and is prescribed at a dose of 45 mg/m² daily for the first 42 days, followed by 14 days starting from the first day of each subsequent consolidation course [89–91].

#Decitabine is administered in a 5-day "window" regimen at a dose of 20 mg/m² [90].

Comments: with initial leukocytosis of 100×10⁹/L or more lumbar puncture is performed not on the first day of induction, but only after leukocytes are reduced to 50×10⁹/L, to avoid a false diagnosis of neuroleukemia due to CSF contamination by peripheral blood blasts and to prevent the risk of spinal canal bleeding caused by coagulopathy [1].

Tab. 2. Cytarabine** doses for intrathecal administration by age [41].

Prophylactic therapy (without initial CNS involvement): intrathecal injections of cytarabine (5 injections): one injection before the start of each treatment block, and after the completion of the last block and recovery of hematopoiesis, 2 additional injections at 1-month intervals.

Therapy for initial CNS involvement: intrathecal injections of cytarabine** are administered once a week until the cerebrospinal fluid is cleared, but at least 3 times. Subsequently, intrathecal cytarabine** administration continues according to the same schedule as prophylactic treatment—that is, before the start of each chemotherapy block, and after the completion of the last block and recovery of hematopoiesis, 2 additional injections at 1-month intervals.

Comments: prophylactic cranial irradiation is administered at least 4 weeks after the end of the last block upon hematopoietic recovery. The last two cytarabine** injections must be given during radiation therapy at a 2-week interval.

Comments: cranial irradiation is performed using a linear accelerator. The radiation field must encompass the entire neurocranium, including the upper cervical spine up to C2 inclusive, the retrobulbar space, and the entire skull base; special attention should be paid to the middle cranial fossa, which often lies deeper than the general level; inclusion of the temporomandibular joints in the irradiation field should not affect field configuration. The daily fraction dose is 1.5 Gy, meaning the patient receives 7.5 Gy per week. The total duration of irradiation is 2 to 3 weeks. Spinal irradiation is not performed in any patient. For patients scheduled for HSCT, irradiation and the last 2 intrathecal cytarabine** injections are performed after transplantation per medical team decision.

Comments: the maintenance therapy phase begins after hematopoietic recovery following the last chemotherapy course. Mercaptopurine** is prescribed at a starting dose of 50 mg/m² orally daily, and cytarabine** at a dose of 40 mg/m² once daily subcutaneously for 4 days each month. The duration of maintenance therapy is 12 months [38, 47].

The value of maintenance therapy following high-intensity "block" therapy is questionable according to published studies. Furthermore, there is evidence of a negative impact of maintenance therapy on overall survival [33, 48]

3.2 Treatment of relapsed and resistant (refractory) forms of AML

Treatment of patients with refractory or relapsed AML, treatment regimens.

1.      FLAIda [85, 103, 181, 182]

#Fludarabine 30 mg/m² as a 30-minute infusion on days 1, 2, 3, 4, 5, for a total of 5 doses. The interval between the start of the #fludarabine infusion and the start of the cytarabine** infusion must be 4 hours

Cytarabine** 2000 mg/m² as a 3-hour infusion every 24 hours on days 1, 2, 3, 4, 5, 10 doses in total

#Idarubicin^** 10 mg/m² as a 60-minute infusion on days 1, 3, 5

(in the absence of idarubicin, #mitoxantrone** 10 mg/m² IV over 60 minutes on days 1, 3, 5 can be used – FLAM regimen)

2. FLA [99, 103, 181, 182]

#Fludarabine 30 mg/m² as a 30-minute infusion on days 1, 2, 3, 4, 5, for a total of 5 doses. The interval between the start of the #fludarabine infusion and the start of the cytarabine** infusion must be 4 hours

Cytarabine** 2000 mg/m² as a 3-hour infusion every 24 hours on days 1, 2, 3, 4, 5, 10 doses in total

• For patients with relapsed and refractory AML in whom intensive chemotherapy is not feasible, it is recommended to administer molecular targeted therapy consisting of #venetoclax** and the demethylating agent #decitabine. [98, 184, 185]

GPP CLevel of Evidence C (Reliability Level - 4)

Comments: #Venetoclax** is prescribed at a dose of 400 mg once daily orally. The duration of #venetoclax** intake is 28 days in children who cannot undergo induction chemotherapy due to a severe somatic condition (severe infectious process, cerebrovascular accident, mechanical ventilation, renal replacement therapy, acute heart and vascular failure, severe liver failure).

Dose modification of #venetoclax** when coadministered with drugs affecting its metabolism.

#Decitabine is prescribed at a dose of 20 mg/m² on days 3-10 of each cycle intravenously. Administration of the first 6 doses of #decitabine is mandatory. If hematopoietic aplasia develops by day 15, along with febrile illness and complete eradication of blasts, the subsequent 6 administrations may be omitted. #Venetoclax** intake continues for all 28 days of the cycle.

The drug #venetoclax** in combination with #decitabine (Ven+Dec) is indicated for the treatment of children with relapsed, refractory AML who are not candidates for intensive induction chemotherapy due to comorbid conditions [84,86,87,98, 184]

Irradiated blood products must be used for transfusion therapy in patients after #fludarabine therapy.

Upon achieving remission, a course of similar therapy without anthracycline is required, followed by allogeneic transplantation from an HLA-genoidentical or alternative donor. Prior to initiating chemotherapy for refractory or relapsed AML, HLA typing of the patient, siblings, and parents must be performed, and the data sent to the transplantation center.

Comments: #sorafenib** in vitro causes inhibition of phosphorylation of the intracytoplasmic part of the ITD-Flt-3 receptor; there has been a report of the successful use of #sorafenib** 300 mg/m2 daily for 47 days followed by maintenance therapy with #sorafenib** 170 mg/m2 daily in a patient with extramedullary relapse of AML after allo-HSCT [50, 51]. Publication of data from ongoing prospective randomized trials of ITD-Flt-3 inhibitors (midostaurin**, gilteritinib) in first-line therapy in children is pending.

• For patients with relapsed and refractory AML, as an alternative therapeutic option to achieve remission, it is recommended to induce remission using the following regimen: #cladribine** (9 mg/m2 for 5 days) with cytarabine** (500 mg/m2 for 5 days), followed by 2 more cycles of DAV (daunorubicin** 30 mg/m2 on days 1-3 as a 72-hour infusion, cytarabine** 250 mg/m2 on days 1-5 as a 120-hour infusion, #etoposide** 200 mg/m2 on days 4 and 5 as a 48-hour infusion) [52].

LEVCLOE 4Level of Evidence C (Level of Likelihood of Evidence - 4)

3.3 Treatment of AML and transient abnormal myelopoiesis in patients with Down syndrome

Children with Down syndrome (DS) have an abnormally high risk of developing hematological malignancies. The incidence of acute myeloid leukemia in children with DS is 150-400 times higher than in patients without DS. At the same time, survival rates and prognosis in children with AML-DS are significantly higher than in children without DS.

Myeloproliferative disorders associated with Down syndrome, due to their unique clinical and biological features, occupy a separate place in the latest WHO classification (2017) and are represented by transient abnormal myelopoiesis (TAM) and AML. TAM occurs in 5-30% of children with DS and AML, accounting for about 20% of all AML cases.

Transient abnormal myelopoiesis (TAM), transient myeloproliferative disorder, transient leukemia is a transient clonal myeloproliferative syndrome, the defining features of which are an increased number of blast cells in the peripheral blood, morphologically and immunophenotypically belonging to megakaryoblasts, as well as the detection of an acquired mutation in the GATA1 gene. This syndrome is characteristic of newborns with Down syndrome. The detection rate of TAM in such patients varies from 5 to 30%. According to literature data, in 80% of cases TAM spontaneously resolves within a few weeks or months after birth (usually up to 6 months). However, in 20-30% of cases it can evolve into AML.

This syndrome most commonly develops in the first days/months of a child's life. Sometimes it can be detected intrauterine and lead to intrauterine fetal demise or death in the neonatal period. Clinical manifestations of TAM can vary from asymptomatic changes in blood counts to severe disseminated leukemic organ infiltration. Clinically manifest TAM develops in 10-30% of patients.

The most common manifestations are hepatosplenomegaly, jaundice, rash, pericardial/pleural effusion, ascites, renal failure, hematological disorders (leukocytosis with a left shift in the leukocyte formula, neutrophilia, thrombocytopenia). It should be noted that there are no specific signs, except for an increased number of blast cells in the blood > 20% and the presence of a mutation in the GATA1 gene. Approximately 20% of newborns have neither clinical nor hematological manifestations of TAM – this is the so-called "silent" TAM.

In 15-20% of cases, TAM can have a severe life-threatening course, which requires therapy with low-dose cytarabine** at a dose of 0.5 to 2 mg/kg.

The manifestation of AML in children with DS usually occurs in the first 5 years of life, with a peak incidence at 2-4 years. According to literature data, children with AML and DS have better treatment results and higher survival rates than children without DS. With reduced-intensity chemotherapy, the probability of AML cure is 80% or more. At the same time, standard intensive chemotherapy (with high doses of anthracyclines and "intensive" induction timing) is associated in such patients with high toxicity and significant mortality from infectious complications [76,77,80].

Patients with Down syndrome may also develop myelodysplastic syndrome (MDS), which is characterized by cytopenia and dysplasia in 1 or more cell lineages. In children, this syndrome is represented by 2 forms: refractory cytopenia and MDS with excess blasts.

It is quite obvious that MDS in patients with Down syndrome inevitably transforms into AML, and therefore such patients require chemotherapy (CT) similar to that received by children with AML-DS [81].

The relapse rate in patients with AML-DS is low and does not exceed 8-10%. However, in the event of a relapse or refractory course of the disease, therapeutic options are very limited (HSCT), and survival rates are extremely unsatisfactory. Overall survival rates of patients with DS and relapsed AML do not exceed 25% [76,77,80].

Thus, the treatment of AML/MDS in children with Down syndrome should be based on reducing the dose of chemotherapeutic agents, avoiding intensive timing, and optimizing the quality of supportive care.

Currently, there is no single established standard of care for AML in children with DS. The ML-DS-2006 protocol is frequently used for treatment.

In Russia, protocols from the German BFM (Berlin-Frankfurt-Münster) study group are used – AML-BFM-98, AML-BFM-2004, and ML-DS-2006. The 3-year survival rate of patients treated in the AML-BFM 98 trial was 90%. In the relatively recent international multicenter trial ML-DS 2006, conducted between 2006 and 2015, therapy intensity was reduced compared to the AML-BFM 98 trial by decreasing the cumulative dose of etoposide**, reducing the number of drug courses, and omitting maintenance therapy. As a result of this treatment, complete remission was achieved in 85% of children. Despite the reduction in chemotherapy, overall and event-free survival rates were 89% and 87%, respectively, with a cumulative relapse/refractory risk of 6%. These results were comparable to the BFM 98 control group. Treatment-related mortality was 2.9% versus 5%. The incidence of severe infectious complications was reduced nearly twofold in the ML-DS-2006 trial [82].

Patients with AML/MDS and DS are recommended to receive therapy according to the ML-DS-2006 protocol. The treatment protocol for all patients includes 4 chemotherapy cycles: remission induction and 3 consolidation cycles.

Remission Induction

AIE: [74, 181, 182]

Cytarabine** 100 mg/m²/day as a continuous IV infusion over 48 hours, starting from the morning of day 1 until the morning of day 3.

Cytarabine** 100 mg/m² every 12 hours as a 30-minute IV infusion from day 3 to day 8 inclusive (12 doses in total);

#Idarubicin** 8 mg/m²/day as a 4-hour IV infusion on days 3, 5, and 7, administered immediately before cytarabine** (3 doses in total);

#Etoposide** 150 mg/m²/day as a 1-hour IV infusion every 24 hours on days 6, 7, and 8 (3 doses in total), administered before cytarabine**;

Cytarabine** intrathecally at an age-adjusted dose on day 1.

Consolidation 1

AI course: [74, 181, 182]

Criteria for initiating chemotherapy: granulocytes > 1000/µL, leukocytes > 2000/µL, platelets > 100,000/µL

Cytarabine** 500 mg/m²/day as a continuous 24-hour IV infusion on days 1–4 inclusive (96 hours in total);

#Idarubicin** 5 mg/m² as a 1-hour IV infusion on day 3 and day 5 (2 doses);

Cytarabine** intrathecally at an age-adjusted dose on day 0.

Consolidation 2

haM: [68, 100, 181]

Criteria for initiating the block: granulocytes > 1000/µL, leukocytes > 2000/µL, platelets > 100,000/µL

Cytarabine** 1 g/m² as a 3-hour IV infusion every 12 hours for 3 days (6 doses in total);

#Mitoxantrone** 10 mg/m²/day as a 30-minute IV infusion once daily for 2 days (2 doses in total);

Cytarabine** intrathecally at an age-adjusted dose on day 0.

Consolidation 3

HA: [74, 181, 182]

Criteria for initiating the block: granulocytes > 1000/µL, leukocytes > 2000/µL, platelets > 100,000/µL

High-dose cytarabine** 3 g/m² as a 3-hour IV infusion every 12 hours on days 1–3 inclusive (6 doses in total);

Cytarabine** intrathecally at an age-adjusted dose on day 0.

If #idarubicin** is unavailable at the clinic, #mitoxantrone** (at a 1:1 conversion ratio with #idarubicin**) or daunorubicin** (at a 1:5 ratio) may be used.

Cytarabine** doses for intrathecal administration by age

Comments: For children with a body weight ≤ 12 kg or age < 1 year, IV chemotherapy doses should be calculated based on the child's body weight (kg) rather than body surface area.

1. perform a complete blood count (CBC) with blood smear review to evaluate erythrocyte, platelet, and leukocyte morphology abnormalities in order to search for and count blast cells;

2. perform a physical examination to identify clinical manifestations;

3. if an elevated blast cell count is detected in the peripheral blood or clinical signs are present, it is necessary to:

   - determine the presence of severe life-threatening symptoms;

   - perform molecular genetic testing for mutations in the GATA1 gene by sequencing.

4. In the presence of life-threatening symptoms (leukocytosis > 100 × 10³/µL, conjugated bilirubin > 83 µmol/L, marked hepatosplenomegaly, hydrops fetalis, pleural/pericardial effusion, renal failure, DIC), treatment with low-dose cytarabine** must be initiated.

5. In the absence of severe symptoms, monitoring until hematopoiesis normalizes, followed by outpatient follow-up until 5 years of age (due to the risk of AML development).

GCP BLOE 3Grade of Recommendation B (Level of Evidence - 3)

3.4 Concomitant and supportive care

• All patients receiving AML therapy are recommended to receive supportive and concomitant care in accordance with relevant clinical guidelines [1, 53–56].

GDR CLE 5Grade of recommendation C (level of evidence – 5)

Comments: Isolation of children in single-bed rooms, infusion therapy, and the administration of colony-stimulating factors as indicated are shown.

Comments: systemic antifungal therapy is continued until neutrophil counts rise above 0.5 × 10⁹/L.

Comments: The choice of initial therapy depends on the patient's performance status, screening results, and prior infection history, as well as local epidemiological data and guidelines. Systemic antimicrobial drugs are administered to patients with AML exclusively via intravenous infusion.

Comments: Glycopeptide antibiotics may be administered additionally, depending on the clinical picture, local guidelines, and patient colonization. The prescription of carbapenems as first-line systemic antibacterial drugs is justified in patients with severe infections, involvement of the abdominal or perirectal regions, or sepsis. Antimicrobial therapy is modified based on clinical symptoms, instrumental findings, and microbiological test results. In a clinically stable condition without infection foci, it is acceptable to continue initial antibacterial therapy for 48–72 hours, as fever is not the sole indicator of infection severity.

Comments: Patients colonized with resistant bacteria require the prescription of reserve-group drugs (in accordance with antibiogram data).

Comments: Upon the development of severe infectious complications and/or sepsis, antibacterial drugs are prescribed at maximum doses, preferably via prolonged infusions due to impaired clearance and fluid redistribution in the body. Reserve-group drugs include colistimethate sodium, polymyxin B**, tigecycline**, #ceftolozane/tazobactam**, ceftazidime/avibactam** (in some situations combined with aztreonam**) [175-178].

• Preemptive antifungal therapy is recommended for all patients with AML if signs of invasive mycosis are detected during a full diagnostic workup: chest CT, bronchoscopy followed by microbiological examination of bronchoalveolar lavage fluid (in accordance with Appendix A3.6) [124, 153-155].

GOW 5Level of Evidence C (Reliability of Evidence 5).

• For all patients with AML and neutropenia and/or hemodynamic instability, fluconazole** is not recommended for the treatment of candidemia [154].

GOW 5Level of Evidence C (Reliability of Evidence 5).

• Upon the development of invasive aspergillosis, it is recommended that all patients with AML immediately initiate systemic antifungal therapy [154-160].

Level of Evidence: 5Grade of Recommendation: C (Level of Evidence: 5).

• Upon the development of invasive mucormycosis, it is recommended that all patients with AML immediately undergo combination therapy including systemic antifungal agents and surgical intervention [154, 161-163].

GOW 4Level of Evidence C (Reliability of Evidence 4).

Comments: Any manifestation of hemorrhagic syndrome (petechial rash, especially on the oral mucosa, face, and anterior chest, any bleeding) and/or a body temperature rise above 37.5^° C, even in the absence of an obvious focus of infection, requires platelet concentrate transfusion even if the peripheral blood platelet count is above 20 × 10⁹/L. Similar indications apply for platelet concentrate transfusion when preparing a patient for invasive procedures.

For the first phase of induction and for performing invasive manipulations (lumbar puncture, central venous catheterization), the platelet count must be at least 30 × 10⁹/L. During the hematopoietic aplasia period following any course of multiagent chemotherapy, in the absence of bleeding and/or infections with febrile neutropenia, platelets must be maintained at a level of at least 15 × 10⁹/L. When infections with febrile neutropenia develop and Amphotericin B** is used, platelets must be maintained at a level of at least 20 × 10⁹/L.

Severe mucosal bleeding, gastrointestinal bleeding, pulmonary hemorrhage, and cerebral hemorrhage are indications for platelet concentrate transfusion regardless of platelet counts.

Patients who have received cladribine** and #fludarabine** must be transfused with irradiated blood products.

Comments: patients who have received cladribine** must be transfused with irradiated blood products.

Comments: Indications and volume of transfusion support are determined by coagulogram parameters and the clinical situation.

Patients who have received cladribine** and #fludarabine** must be transfused with irradiated blood products.

Fresh frozen plasma transfusions are performed only for major coagulogram abnormalities: fibrinogen less than 1 g/L, prothrombin index less than 50%, aPTT greater than 55 seconds.

4. Medical Rehabilitation and Sanatorium-Resort Treatment

Approach to rehabilitation and follow-up care for patients with AML. Follow-up care includes systematic examinations and targeted laboratory and instrumental evaluations aimed at assessing the remission status of the underlying disease and potential complications associated with prior multiagent chemotherapy.

There are no special rehabilitation methods for AML.

Comments: after completion of treatment, it is recommended to maintain a healthy lifestyle and avoid sun exposure and physiotherapeutic procedures.

Multiagent chemotherapy can cause cardiotoxicity, hepatotoxicity, neurotoxicity, nephrotoxicity, and other toxicities, the consequences of which may persist even after its completion.

5. Prevention and Dispensary Observation

Primary prevention of AML is not possible due to its low baseline incidence and undetermined causes.

Prevention of disease relapse is based on the full implementation of the first-line therapy protocol, performance of hematopoietic stem cell transplantation (HSCT), and regular dynamic monitoring.

1. Patients who underwent allogeneic HSCT are followed up in accordance with the transplant center's guidelines.

2. Patients without allogeneic HSCT:

1) complete blood count with differential once a month for the first 3 months, then once every 6 months for 5 years

2) molecular genetic blood test for human immunodeficiency virus HIV-1, determination of hepatitis B virus surface antigen (HBsAg) in the blood, and determination of antibodies to hepatitis C virus in the blood 6 months after the completion of chemotherapy.

3. General clinical biochemical blood analysis assessing albumin, ALT, AST, LDH, bilirubin (total and direct), urea, creatinine, and ferritin once a year for 5 years

4. ECG and echocardiography once a year for 5 years

5. CT/MRI of extramedullary lesion sites 6 months after the completion of chemotherapy

GCR CLEL 5Grade of Recommendation C (Level of Evidence – 5)

6. Organization of Medical Care

Indications for planned hospitalization:

1. Suspicion/establishment of acute leukemia diagnosis

2. Diagnosis of AML relapse

3. Administration of the next chemotherapy cycle in an inpatient setting

4. Performance of scheduled HSCT

5. Performance of elective surgical interventions

6. Performance of elective extracorporeal blood purification methods and renal replacement therapy

7. Administration of blood component replacement therapy

Indications for emergency hospitalization:

Emergency conditions in patients with AML and suspected AL:

- leukocytosis greater than 100 × 10⁹/L

- febrile neutropenia and infectious complications during neutropenia following a course of chemotherapy

- hemorrhagic syndrome

- thrombotic complications

- need for emergency blood component replacement therapy

- other systemic disorders caused by the underlying disease or developed as a result of treatment

Indications for patient discharge from the hospital:

1. Restoration of peripheral blood counts (leukocytes > 1 × 10⁹/L, granulocytes > 0.5 × 10⁹/L, platelets > 50 × 10⁹/L, hemoglobin > 80 g/L) following the next course of chemotherapy

2. Normothermia for 3–5 days and absence of uncontrolled infectious complications in the post-course period

3. Resolution of hemorrhagic complications

4. Resolution of thrombotic complications

5. Resolution of systemic disorders caused by the underlying disease or developed as a result of treatment.

   The conclusion regarding the feasibility of transferring the patient to a specialized medical organization is made after a prior consultation based on the provided medical documents and/or a preliminary examination of the patient by medical specialists of the medical organization to which the transfer is planned.

7. Additional Information

“Molecularly targeted” therapy

Progress in understanding the molecular pathogenesis of AML has led to the development of novel “molecular” agents, i.e., molecules whose mechanism of action involves interacting with proteins whose functions are altered as a result of mutations or translocations (targeted action). For example, genetic alterations lead to mutations in genes that activate signal transduction cascades (e.g., FLT3, KIT, RAS), gene fusions, or mutations resulting in increased or decreased transcriptional activity (e.g., PML-RARA, RUNX1-RUNX1T1, CBFB-MYH11, CEBPA), or impaired function of genes involved in signaling (e.g., NPM1, NUP98, NUP). Although efficacy in AML has been demonstrated for some molecularly targeted agents, it was clear already at the clinical trial stage that most of them need to be used in combination with standard cytotoxic drugs. Currently, a large number of clinical trials are underway to study the efficacy in AML and safety of agents from various pharmaceutical groups.

Criteria for Evaluating the Quality of Medical Care

References

Appendix A1. Working Group Composition

Maschan A.A. – MD, PhD, Professor, Corresponding Member of the Russian Academy of Sciences, Director of the Institute of Hematology, Immunology and Cell Technologies, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health, Professor at the Department of Hematology, Oncology and Radiation Therapy, Pediatric Faculty, Pirogov Russian National Research Medical University of the Russian Ministry of Health

Maschan M.A. – MD, PhD, Deputy General Director for Science, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health, member of the Russian Society of Pediatric Oncologists and Hematologists

Novichkova G.A. – MD, PhD, Professor, Scientific Director, Head of the Department of Hematology and Cell Technologies, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health, Chief freelance pediatric specialist oncologist/hematologist of the Russian Ministry of Health

Popa A.V. – MD, PhD, Professor of the Russian Academy of Sciences, Head of the Department of Epidemiology and Late Effects Research in Childhood Cancer Survivors, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health, Professor at the Department of Propaedeutics of Childhood Diseases, Pirogov Russian National Research Medical University of the Russian Ministry of Health

Solopova G.G. – PhD in Medicine, Deputy Chief Medical Officer for Infection Control, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health

Abashidze Z.A. – Hematologist at the Baffled Ward Department, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health

Rumyantsev A.G., MD, PhD, Academician of the Russian Academy of Sciences, Scientific Director of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health, Professor at the Department of Hematology, Oncology and Radiation Therapy, Pediatric Faculty, Pirogov Russian National Research Medical University of the Russian Ministry of Health

Valiev T.T. – MD, PhD, Head of the Chemotherapy Department for Hemoblastoses No. 1, Dr. L.A. Durnov Research Institute of Pediatric Oncology and Hematology, N.N. Blokhin National Medical Research Center of Oncology of the Russian Ministry of Health

Kirgizov K.I., PhD in Medicine, Deputy Director of the Dr. L.A. Durnov Research Institute of Pediatric Oncology and Hematology, N.N. Blokhin National Medical Research Center of Oncology of the Russian Ministry of Health

Kalinina I.I., PhD in Medicine, Hematologist, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Russian Ministry of Health

No conflict of interest.

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience of the clinical guidelines:

1. Pediatric oncologists-hematologists.

2. Hematologists;

3. Pediatric oncologists;

4. Pediatricians;

5. Anesthesiologists-intensivists;

6. Clinical pharmacologists.

Methodology for evidence collection

Methods used for collecting/selecting evidence:

Search for publications in specialized peer-reviewed periodicals;

Search in electronic databases.

Databases used for collecting/selecting evidence:

The evidence base for the recommendations includes publications from the Cochrane Library, PUBMED, and MEDLINE databases. The search depth was 30 years.

Methods used for analyzing evidence:

• Reviews of published meta-analyses;

• Systematic reviews with evidence tables.

• Methods used for assessing the quality and strength of evidence:

• Expert consensus;

• Evaluation of the significance of evidence in accordance with the evidence rating scheme (Tables A2.1–A2.3).

Table A2.1. Scale for assessing the levels of evidence (LE) for diagnostic methods (diagnostic interventions)

Table A2.2. Scale for assessing the levels of evidence (LE) for methods of prevention, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, therapeutic, and rehabilitative interventions)

Table A2.3. Scale for assessing the grades of recommendation (GR) for methods of prevention, diagnosis, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines.

Updating is carried out at least once every three years, taking into account newly emerging information on the diagnosis and management tactics for patients with AML. The decision to update is made by the Russian Ministry of Health based on proposals submitted by medical professional non-profit organizations. The formulated proposals must take into account the results of a comprehensive assessment of medicinal products, medical devices, and the results of clinical probation.

Appendix A3. Reference Materials

Appendix A3.1. Diagnostic tests and examinations used in patients with newly diagnosed AML

Appendix A3.2. Chemotherapy regimens in AML

In Russia, protocols of the German BFM (Berlin-Frankfurt-Münster) study group are traditionally used. The 1998 protocol was evaluated in Germany for 5 years; this study is now completed, and its results have been summarized. In 424 patients, the remission rate, overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS) were assessed. The results are presented in Table 1. The treatment regimen is described in the «Treatment Description» section.

Table 1. Treatment outcomes according to the AML-BFM-98 protocol.

EFS – event-free survival, OS – overall survival, RFS – relapse-free survival.

The AML-BFM-98 study, designed to compare the efficacy of early 6-week post-remission therapy with standard doses of cytarabine**, prednisolone**, mercaptopurine**, cyclophosphamide**, and doxorubicin** versus two blocks of high-dose cytarabine**, demonstrated similar efficacy but a higher incidence of infectious complications in the prolonged therapy group. Consequently, the BFM group abandoned the 6-week consolidation used for 20 years in favor of short high-dose therapy [39].

Currently, most clinics in the Russian Federation use modified regimens of the BFM 2004 protocol [39].

Treatment description.

Therapy according to the modified AML-BFM-98/2004 protocol is indicated for children with de novo AML who cannot be enrolled in contemporary clinical trials. Patients with secondary and biphenotypic AML may also receive this treatment, although individual protocol adjustments may be required for them.

Modified AML-BFM-2004 protocol (high-dose therapy branch)

Chemotherapy according to the block-based branch of the protocol consists of 5 chemotherapy courses and maintenance therapy with daily mercaptopurine** and monthly standard-dose cytarabine** (Regimen 1).

Blocks [68, 181, 182].

AIE Remission Induction:

Initiated regardless of the presence of leukopenia and thrombocytopenia!

Cytarabine** 100 mg/m2 per day on days 1–2 as a continuous infusion

Cytarabine** 100 mg/m2 as a 30-minute infusion every 12 hours on days 3–8 as a continuous infusion

#Idarubicin** 12 mg/m2 per day as a 4-hour infusion for 3 days (depending on the prescribed treatment protocol)

#Etoposide** 150 mg/m2 as a 1-hour infusion on days 6, 7, 8

Cytarabine** intrathecally at an age-adjusted dosage on days 1 and 8.

HAM20:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

High-dose cytarabine** 3000 mg/m2 as a 3-hour infusion every 12 hours on days 1 to 3;

#Mitoxantrone** 10 mg/m2 as a 60-minute infusion on days 3 and 4;

Cytarabine** intrathecally at an age-adjusted dosage on day 1.

AI:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

#Cytarabine** 500 mg/m2 as a 2-hour infusion every 12 hours for 4 days (8 doses in total)

#Idarubicin** 7 mg/m2 as a 60-minute infusion for 2 days, 2 doses in total Cytarabine** intrathecally at an age-adjusted dosage on days 1 and 6.

haM:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

#Cytarabine** 1000 mg/m2 as a 3-hour infusion every 12 hours for 3 days (6 doses in total)

#Mitoxantrone** 10 mg/m2 as a 30-minute infusion for 2 days (2 doses in total) Cytarabine** intrathecally at an age-adjusted dosage on days 1 and 6.

HAE:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

Cytarabine** 3000 mg/m2 as a 3-hour infusion every 12 hours on days 1, 2, 3 (6 doses in total)

#Etoposide 125 mg/m2 as a 2-hour infusion on days 2, 3, 4, 5 (4 doses in total)

Cytarabine** intrathecally at an age-adjusted dosage on day 1.

Maintenance therapy:

In BFM group protocols, maintenance therapy with subcutaneous cytarabine** at 40 mg/m2 once daily for 4 days each month is administered after hematopoietic recovery following the last intensive chemotherapy course until 18 months from the start of treatment.

However, other study groups do not use low-dose maintenance therapy following similar intensive chemotherapy [38].

Prophylaxis of complications associated with pulmonary and cerebral leukostasis in initial hyperleukocytosis. This complication is most typical for patients with M4 and M5 variants with initial leukocytosis > 50×10⁹/L and M1 and M2 variants with initial leukocytosis > 100×10⁹/L, although it may develop at substantially lower leukocyte counts. The highest-risk population for leukostasis syndrome consists of young children with monocytic AML subvariants accompanied by coagulopathy. In this group of patients, the administration of full doses of cytosine arabinoside is associated with a sharply increased risk of leukostasis; therefore, such patients are indicated for leukocytapheresis (or exchange transfusion in patients under 3 years of age) and/or medical cytoreduction.

The latter may include mercaptopurine 40 mg/m2/day combined with hydroxyurea at a dose of 1500 mg/m2/day and administered until leukocytosis drops below 50×10⁹/L.

The experience of the National Medical Research Center of Pediatric Hematology, Oncology and Immunology (Dmitry Rogachev Center) demonstrates the efficacy of cytoreduction with reduced doses of etoposide** and daunorubicin** (or another anthracycline) without cytosine arabinoside. Daunorubicin** (22.5 mg/m²/day) and etoposide** (50 mg/m²/day) are administered as a continuous infusion until the leukocyte count reaches 50×10⁹/L, but for no more than 3 days. This is followed by induction with cytarabine** along with anthracycline and VP-16 doses, from which the cumulative dose of these drugs received during the cytoreduction phase is subtracted. In addition, throughout the cytoreductive phase, dexamethasone** is administered intravenously as an IV push at a dose of 10 mg/m2/day (divided into 3 administrations). Red blood cell replacement transfusions should not be performed throughout the cytoreduction course unless the hemoglobin level drops below 70 g/L [40].

Induction and consolidation course options [68, 69, 70, 71, 72, 73, 181, 182]

AML-BFM DS 2006 Protocol

In children with AML developing on the background of Down syndrome, the toxicity of high-dose anthracyclines combined with high-dose cytarabine** is significantly higher than in patients without Down syndrome; therefore, they should receive treatment according to a specialized protocol (AML-BFM DS 2006) [74].

Figure 2. General chemotherapy plan according to the AML-BFM DS 2006 protocol.

Blocks [68, 69, 181, 182]

AIE:

Cytarabine** 100 mg/m²/day by continuous infusion on days 1 and 2, then

Cytarabine** 100 mg/m2 by 30-minute infusion every 12 hours on days 3 - 8;

#Idarubicin** 8 mg/m2 as a 60-minute infusion every 24 hours on days 3, 5, 7 before cytarabine**;

#Etoposide** 150 mg/m2 as a 2-hour infusion on days 6–8, 6 hours before cytarabine**;

Cytarabine** intrathecally at an age-adjusted dose on day 1.

AI:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

Cytarabine** 500 mg/m2/day by continuous infusion for 4 days;

#Idarubicin** 5 mg/m2 by 60-minute infusion on days 3 and 5;

Cytarabine** intrathecally at an age-adjusted dose on day 0.

haM:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

#Cytarabine** 1000 mg/m2 by 3-hour infusion every 12 hours for 3 days (6 doses in total)

#Mitoxantrone** 10 mg/m2 by 30-minute infusion for 2 days (2 doses in total)

Cytarabine** intrathecally at an age-adjusted dose on day 0.

HA:

Condition for starting the block: granulocytes > 1000/µl, leukocytes > 2000/µl, platelets > 100,000/µl

High-dose cytarabine** 3 g/m² as a 3-hour infusion every 12 hours on days 1–3;

Cytarabine** intrathecally at an age-adjusted dose on day 0.

Appendix A3.3. Indications for allo-HSCT in the first complete remission of AML

Table 3.3.1. Synthetic indications for allo-HSCT in the first complete remission of AML based on molecular-genetic and clinical characteristics of AML and the risk of transplant-related mortality [75]

Appendix A3.4. Molecular genetic classification of AML

Table 3.4.1. European LeukemiaNet (ELN) molecular-genetic classification of AML (2017) [25].

(*) low allelic ratio (0.5)

(**) high allelic ratio (>0.5)

(***) if these mutations are detected in patients with favorable cytogenetic abnormalities, their presence is not significant.

Appendix A3.5. Molecular genetic prognostic risk factors in AML

Table 3.5.1. Molecular genetic and clinical features of AML stratifying patients into favorable and adverse prognostic groups [25]

Appendix A 3.6 Diagnosis of Infectious Complications

Table A 3.6

Appendix B. Physician Action Algorithms

Appendix C. Patient Information

Acute myeloid leukemia is a rare malignant hematopoietic disorder characterized by uncontrolled proliferation, impaired differentiation, and accumulation of immature hematopoietic cells in the bone marrow and peripheral blood.

When AML develops, all organs and systems are affected due to the generalized (disseminated) nature of the disease. The clinical picture is dominated by syndromes associated with the progressive accumulation of malignant cells in the bone marrow, as well as in the liver and spleen; involvement of the central nervous system and other organs and systems is also possible. The most frequent manifestations of the disease include:

1) Fever.

An increase in body temperature above 38.0 °C may be the first and only manifestation of the disease, driven by the presence of blast (tumor) cells, the release of their metabolic products, and the development of an infectious process.

2) Infectious process (tonsillitis, stomatitis, pneumonia, etc.) develops due to the displacement of normal hematopoietic cells—leukocytes/neutrophils—by blast cells, which normally protect a child's body from bacterial and fungal infections.

3) Hemorrhagic syndrome (bleeding, bruising) resulting from the displacement of platelets (cells responsible for stopping bleeding) from normal hematopoiesis by blast cells.

4) Anemic syndrome (pallor, lethargy, rapid fatigability, weakness) also develops due to the lack of erythrocytes (decreased hemoglobin) in the bone marrow of a patient with AML.

5) Bone pain and pain in other affected organs.

6) Enlargement of the liver and spleen, onset of jaundice.

7) Central nervous system involvement may manifest as headache, vomiting, and seizures.

Establishing a diagnosis requires a wide range of blood tests, bone marrow puncture, lumbar puncture, as well as X-ray and tomographic imaging. Chemotherapy requires the placement of a central venous catheter (CVC) to avoid numerous punctures of peripheral veins.

All invasive procedures (punctures, CVC placement) are performed under general anesthesia.

Treatment of acute myeloid leukemia generally consists of two phases: an intensive therapy phase and hematopoietic stem cell transplantation. During the intensive phase, chemotherapy is administered at short intervals, and inpatient care is frequently required. First-line chemotherapy consists of three main drugs: cytarabine**, etoposide**, daunorubicin** (#idarubicin** or mitoxantrone). This is followed by several courses of high-dose chemotherapy.

Side effects of chemotherapy:

1. Hair loss

2. Nausea and vomiting

3. Decreased / altered appetite

4. Fever

5. Development of infectious foci

6. The goal of therapy is to achieve disease cure, prevent relapses and complications associated both with disease manifestations and with the development of induced (chemotherapy-induced) hematopoietic aplasia. The total duration of therapy is about 6 months, without HSCT. Reducing the duration of therapy may increase the risk of disease relapse. When therapy is administered in accordance with modern treatment protocols, the probability of recovery is about 70%.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Not applicable.