AML (BSH 2015, ELN 2022, BSH 2022, BSH 2022(2))

Precursors – CD34+, CD38+, CD117+, CD133+, HLA-DR+

Granulocytes – CD13+, CD15+, CD16+, CD33+, CD65+, cMPO+

Monocytes – NSE+, CD11c+, CD14+, CD64+, lysozyme, CD4+, CD11b+, CD36+

Megakaryocytes – CD41+, CD61+, CD42+

Erythroid – CD235a+

Intro

Median Age: 70 years

Age <65: 3-8 cases per 100,000 adults per year. 40% 5-year OS

Age >65: 9-17 cases per 100,000 per year. 10% 5-year OS

WHO-HAEM5 Classification

(Note: ICC classification also published the same year, see below)

Notes

• >20% blasts no longer required for AML with defining genetic abnormalities (except CEBPA, BCR-ABL1)

• ‘post cytotoxic therapy’ (pCT) can be added as suffix to myeloid diagnoses where indicated by medical history, e.g. CMML-pCT.

• See WHO-HAEM5 for detailed sub-sections:

  • AML, myelodysplasia-related: list of defining abnormalities.

  • AML, definitions by differentiation

  • Myeloid neoplasms associated with germline predispositions

  • Mixed lineage phenotypes

ICC 2022 Classification

Unfortunately two classification systems were published in WHO and ICC

They are the same in principle, e.g. genetics > morphology, and the change to blast % cutoffs

The ELN have opted to use the ICC. You can see the ICC 2022 Classification here.

Some Significant Genetic Mutations

PML-RARA translocation      t(15;17) – APML

NPM1 mutation                     1o genetic lesions (“Class II”) impairing haemopoietic differentiation

CEBPA mutation                    1o genetic lesions (“Class II”) impairing haemopoietic differentiation

FLT3-ITD                                “Class I” mutation found in approx. 1/3 of AML cases.

RUNX1                                   Alters transcription activity

IDH1&2                                  Mutations lead to arrest of haematopoietic differentiation

KMT2A                                   New name for MLL

DNMT3A, TET2, ASXL1        Often present in preleukaemic stem cells —> may persist after Rx

Clonal Haemtopoeisis of Indeterminate Potential (CHIP)

• Found from large, population-level cohorts of elderly, seemingly healthy subjects

• May behave like MGUS / MBL in terms of risk to progression of AML

• Commonly DNMT3A, ASXL1, TET2, SF3B1, SRSF2

Diagnosis

Basics

• FBC, film

• Biochemistry, Coag,

• HIV, Hep A/B/C

• HLA-typing

• Urine dip, Pregnancy test

• CXR

• Oocyte / Sperm cryopreservation

Morphology

• Aspirate mandatory, trephine optional

• May-Grunwald-Giemsa or Wright-Giemsa stain

• >20% Blasts in marrow for morphological AML diagnosis (Exceptions: t(15;17), t(8;21) and inv(16))

Immunophenotyping

• Used to determine lineage

• >20% of leukaemic cells expressing a marker counted as positive, as a general rule

• Flow blast count is not a substitute for morphological count.

• Examples of specific phenotypes:

  • Acute megakaryoblastic - CD41+, CD61+ (CD42 usually lost on megakaryoblasts)

  • t(8;21) RUNX1:RUNX1T1 - CD19+, CD56+/-, Strong CD34+, Weak CD33+, MPO+

  • t(15;17) APML - High SSC, CD33+, CD13+, CD117+, MPO+, CD34-, HLA-DR-, CD11b-

  • BPDCN - CD123+, CD4+, CD56+, HLA-DR+, CD34-, CD13-

Cytogenetics

• 55% of AML cases have detectable chromosome abnormalities

• Minimum of 20 metaphases must be examined for a normal karyotype

Molecular Cytogenetics (FISH)

• PML-RARA, RUNX1-RUNX1T1, CBFB-MYH11

• KMT2A fusion gene, 5q deletion, 7q deletion

Molecular Genetics (RT-PCR)

• Detects fusion genes, such as those listed under FISH

• Detects somatic mutations – NPM1, FLT3, CEBPA, KMT2A, RUNX1, KIT, TET2, IDH1

• NPM1, FLT3 and CEBPA should be tested as a minimum in pts with normal cytogenetics

• Can be use for MRD monitoring of AML cases with NPM1, PML::RARA or CBF / KMT2A fusions

Genome-wide studies

• Research methods for identification of new genetic abnormalities

• Single Nucleotide Polymorphism (SNP)-arrays

• High-throughput DNA sequencing

• Large scale RNA interference screens

• Testing paired tumour + germline (e.g. skin) samples to investigate for germline predisposition, consider in AML cases with RUNX1, CEBPA, DDX41, ANKRD26, ETV6 or GATA2 mutations present.

Minimum genetic tests for all new AML patients in 2022 (BSH 2022)

• FISH/PCR/Karyotype for Inv16 (CBFB::MYH11), t(8;21) (RUNX1::RUNX1T1) & KMT2A (MLL)

• Karyotype

• Molecular for FLT3-ITD, FLT3-TKD, NPM1

• NGS Panel to include ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, ZRSR2, TP53, FLT3, IDH1, IDH2, DNMT3a and WT1

Germline predisposition (UKCGG 2023, ELN 2022)

Increasing number of gene mutations associated with heritable risk of leukaemia

Somatic gene varaints w/ variant allele frequency (VAF) approaching 50% suggest possible germline involvement

• Potential cases will usually be reviewed at a specialist haematopathology MDT

• These patients may warrant germline testing, e.g. skin biopsy

• UKCGG: Offer germline testing for pathogenic or likely pathogenic variants with VAF >20-30%

Consenting for germline testing

• Ideally start conversation prior to somatic testing, mandatory prior to germline testing itself

Source of germline samples

• Skin biopsy or remission bone marrow aspirate are preferred

• Blood and saliva unsuitable for testing in setting of haematological malignancies

• Other samples currently have various limitations to testing in UK. Examples discussed in link above.

Examples

• DDX41 variants, first reported 2015, are now the most strongly associated with germline predispositions

  • Present in >5% of adult AML. Median age of onset in later life.

  • Modest disease penetrance (40% by age of 90 and <30% patients report a FHx of haem malig)

• Other potential genes are RUNX1, CEBPA, ETV6, GATA2, TP53, TERT, TERC, ANKRD26, CHEK2

Prognostic Factors

Patient-Related Factors (predict TRM)

• Age

• Co-morbidities

AML-Related Factors (predict response to treatment)

• WBC

• Prior MDS

• Prior Cytotoxic chemotherapy

• Cytogenetics

  • Strongest AML-related prognostic factor predicting response to initial therapy

  • Favourable, Intermediate and Adverse

• Molecular Genetics

  • Becomes relevant when patient is cytogenetically normal (CN-AML)

  • E.g. FLT3-ITD poorer prognosis

  • E.g. NPM1 and CEBPA mutations have favourable prognosis

• Minimal Residual Disease (MRD) monitoring

  • Flow 1 log less sensitive but more available than RT-PCR

  • MRD status prior to allograft significantly affects survival post-transplant

Personalised risk calculator available from the Sanger Institute (currently a reserach tool only)

ELN Risk Stratification by Genetics 2022

ELN Response Assessment

• Performed between day 21-28 of induction chemotherapy (e.g. DA 3+7)

• CR = marrow blasts <5%, Neut >1, Plt >100, No circulating blasts

• CR with MRD negativity

• CRh, CRi, PR, No Response (see ELN for details, pg 1361)

(N.B. NPM1 MRD positivity after 2 cycles of induction associated with very poor prognosis)

Management

Adults 18-60 years old

• Induction therapy achieves CR in 60-80% of adults <60 y.o. (TRM 5-10%)

  • Current trial, AML19 – DA vs FLAG-Ida, each with 1 or 2 doses Myelotarg

  • Addition of midostaurin for pts with FLT3 mutations

• Postremission therapy

  • Standard of care is 2nd DA followed by 2 x HD Cytarabine

  • Allograft in 1st CR offers significant OS benefit if intermediate or adverse AML

  • Allograft TRM 15-50%

  • Allograft LT survival for adverse AML in 1st CR is 30% (but chemo alone dismal)

Adults >60 years old (BSH 2022)

• Remission induction chemotherapy provides better QOL and longer survival than supportive care alone so offering induction chemo should be considered

• All patients

  • Assess presence of frailty

  • Comprehensive geriatic assessment (GA) can aid decision making / sometimes prognosis

  • GA includes comorbidity, cognition, mental health, functional status, frailty, nutrition, polypharmacy, social support, quality of life. BSH good practice paper includes several of these scores in appendices.

  • Prophylactics: Quinolones, Aciclovir, Azole anti-fungals, Flu/Covid vaccination

• 60-74 years old

  • Standard induction chemo —> CR 50%, TRM 10-20%, 2-yr OS 50%

  • RIC Allograft has been performed up to age of 74

  • Venetoclax + Azacitidine. NICE approved 2022 for patients not fit for intensive induction. Based on VIALE-A trial 2020 - 400 pts, median age 76, CR rate 36%, CR+CRi 66%. Long-term outcomes awaited.

  • Venetoclax most effective in NPM1 mutated, FLT3-ITD negative AML but approved for all cytogentic groups.

• >75 or not fit for intensive chemo

  • Venetoclax + Azacitidine. NICE approved 2022 for patients not fit for intensive induction. Based on VIALE-A trial 2020 - 400 pts, median age 76 (oldest 91), CR rate 36%, CR+CRi 66%.

  • Azacitidine monotherapy if blasts 20-30% in marrow - CR 10-30%, median OS 6-12 months

  • Hydroxycarbamide

  • Supportive care alone

•  Relapse

  • Re-assess molecular status —> to aid consideration of small molecules, clinical trial

Therapy-Related AML

• Many pathways, poorly understood but two groups stand out

  • 5-7 years post alkylating agents or irradiation —> 5q or 7q deletion AML

  • 2-3 years post topoisomerase II drugs —> MLL or RUNX1 AML

• Poor prognosis

• Often excluded from trials so data lacking. Allograft highest chance of long term survival

Relapsed AML

• Majority of patients with a CR will relapse within 3 years

• 1-year survival 70% for favourable AML, 16% for adverse

Other NICE Approved Agents

• Gemtuzumab ozogamicin (Myelotarg)

  • Anti-CD33 combined with calicheamicin (DNA synthesis inhibitor)

  • Approved for previously untreated AML, where patient is known to have favourable, intermediate or unknown cytogenetics at the start of treatment.

• CPX-351

  • Liposomal daunorubicin + cytarabine combination.

  • Thought better marrow take up and longer half-life (longer cytopenias as a result)

  • Approved for Therapy-related AML and AML with MDS-related change

• Midostaurin (FLT3 Inhibitor)

  • Approved for FLT3-ITD positive patients, when given in combination with DA

• Gilteritinib (FLT3 Inhibitor)

  • Approved as single agent therapy for relapse

  • SE’s include 3-4% Differentiation syndrome

  • ADMIRAL 2019

• Other new agents - see bottom of page

Special situations

• Hyperleukocytosis (WBC >100) – hydroxycarbamide until WBC <10-20

• CNS involvement - <5% of patients. 3 x per week IT cytarabine until no blasts

• Myeloid sarcoma – normal AML induction +/- radiotherapy

Supportive Care

• Fungal, viral and bacterial prophylaxis

• Platelet, red cell transfusions

AML 19 Trial – Adults with AML or High Risk MDS

4 Questions:

1.     Is the use of 2 doses of Myelotarg superior to 1 dose when combined with Da or FLAG-Ida?

2.     Does FLAG-Ida+GO induction improve survival compared to DA(60)+GO?

3.     Does the addition of 1 or 2 courses of high dose Ara-C consolidation to 2 courses of FLAG-Ida improve survival?

4.     In high-risk patients, is CPX-351 superior to FLAG-Ida at induction?

Flow for patients not known to be high risk:

Flow for patients known to be high risk at diagnosis:

Further randomisation available for patients who become high risk at any point during treatment.

Indications for transplant:

• All patients defined as high-risk at any point

  • At diagnosis: if patient has known adverse risk cytogenetics

  • Post course 1: high risk genotype (mutated FLT3-ITD + normal NPM1), or refractory

  • Post course 2: mutated NPM1 transcripts still detectable in PB, or refractory

AML in Pregnancy

General Points

• MDT approach

• Diagnose as per the WHO classification

• Treat without delay, DA(60) 3+10

• Use actual body weight

• Avoid quinolones, tetracyclines, sulphonamides

• CMV negative products

Diagnosis in first trimester

• Successful pregnancy outcome is unlikely and spontaneous pregnancy loss dangerous for patient (bleeding in thrombocytopenia / coagulopathy / infection)

• Counsel patient on termination of pregnancy

Diagnosis at 12-24 weeks

• Balance risks of foetal chemotherapy exposure against premature delivery

• Chemotherapy in 2-3rd trimester rarely causes congenital malformation but does increase risk of late miscarriage, prematurity, fetal growth restriction and neonatal sepsis.

• Where possible, deliver baby at least 3 weeks post-chemotherapy to reduce neonatal myelosuppression

Diagnosis beyond 32 weeks

• Consider delivering baby first

• NVD preferred over C-section

• Active management of third stage of labour is recommended

Supportive therapies

• Anti-emetics – Cyclizine preferred

• Abx - Penicillin, cephalosporins, metronidazole, erythromycin safe in pregnancy

• Anti-fungal – Ambisome preferred

Targeted Therapies (BJH 2018)

(drugs in italics are currently FDA approved in AML)

Only 3% of AML cases now have no detectable causative mutation

CD33-targeted therapy – Gemtuzumab ozogamicin (GO, Myelotarg), Vadastuximab talirine

CD33 highly expressed on AML blasts, and increasingly less so as myeloid cells differentiate

It is not expressed on CD34+ pluripotent stem cells

On non-haemopoitic cells, CD33 is found on hepatocytes —> risk of VOD

Myelotarg is a combo of Anti-CD33 and calicheamicin, a cytoxic antibiotic.

Liposomal Preparations - CPX-351 (Liposomal Daunorubicin + Cytarabine)

Improves OS in phase 3 study, particularly in therapy-related / MDS-related AML

FLT3 Tyrosine Kinase Inhibitors – Midostaurin, Quizartinib, Crenolanib, Gilteritinib, Sorafenib

FLT3 mutations present in a third of AML cases

RATIFY trial

-       Midostaurin + DA(3+7) induction for FLT3-ITD AML. Placebo controlled.

-       Greatest impact when as close to diagnosis as possible. Maintenance therapy not effective.

-       Median OS in younger adults 74 months with midostaurin, 25 months with placebo

-       Only additional side effect was an increased rate of grade 3 rash/desquamation.

The other drugs listed are second generation FLT3 TKI’s with more potent, more specific action.

Quizartinib has been used in relapsed/refractory patients, allowing some to bridge to transplant.

IDH Inhibitors – Enasidenib (IDH2 inhib), ivosidenib (IDH1 inhib)

IDH1 or IDH2 (Isocitrate DeHydrogenase) mutations present in 20% of AML cases. IDH is an enzyme in the kreb cycle. Mutant IDH1 and IDH2 produces an abnormal metabolite which blocks normal cell differentiation.

Enasidenib trialled in R/R AML —> Median OS 9 months (19 months for patients in CR)

Immune Checkpoint Inhibition – Nivolumab, Pembrolizumab

Nivolumab combined with azacitidine in older patients appears tolerable and some benefit.

CDK9 Inhibitors - Alvocidib

CDK9 regulates MCL1 expression. MCL1 is an anti-apoptotic protein.

Others

Monoclonals - Magrolimab (Anti-CD47), Cusatuzumab (Anti-CD70)

Bispecific Antibodies – Flotezumab (CD123+CD3) looks promising

Smoothened inhibitors - Glasdegib

E-selectin inhibitor

Pracinostat (HDAC inhibitor)

CART Cells – CD123 (IL3 receptor) present on 90% of blast cells. Has been used to bridge to HSCT