Acute Myeloid Leukamia, Myelodysplastic Syndromes, Chronic Myeloid Leukaemia

Question 1

Notes on genetic pathology of AML

Answer 1

AML genomes have fewer mutations than most other adult cancers - average 13 mutations per sample
- an average 5 mutations that are recurrently mutated per sample

Pathways in which mutations occur
- Transcription factor fusion 18%
- NPM1 27%
- Tumour suppressor genes 16%
- DNA methylation genes 44%
- Signalling genes 59%
- Chromatin modifying genes 30%
- Myeloid transcription factors 22%
- Cohesin complex genes 13%
- Spliceosome complex genes 14%

Mutation exhibit cooperation and mutual exclusivity
AML oligoclonal at diagnosis and clonal evolution with the addition of new mutations is common after chemotherapy exposure

Question 2

Epidemiology of AML

Answer 2

4/100,000 Australians
Predominantly elderly >55-60 years. Treatment strategies usually curative for younger patients
Mildly more common in males

Question 3

Investigations for AML

Answer 3

Symptoms typically rapid onset of symptoms of bone marrow failure
CBC and blood film -> blasts
Definitive diagnosis -> bone marrow biopsy. Taken from iliac crest (aspirate and trephine) or sternum (aspirate only). WHO diagnosis based on:
1. Morphology - AML >20% myeloblasts on aspirate
2. Flow cytometry (proteins on cell surface)
3. Genetics
4. Clinical syndrome
Biochem, coag, urinalysis
Hep A, B, C, HIV
Pregnancy testing
HLA typing - if BM transplant possibility in future

Comorbidity assessment -> CXR, ECG, ECHO/GHPS
Fertility assessment -> oocyte and sperm cyropreservation
Vascular access

Question 4

WHO diagnostic classification (hierarchy)

Answer 4

AML with recurrent genetic abnormalities
AML with dysplasia related changes
Therapy-related myeloid neiplasm -> survivors of breast cancer/lymphoma, typically use of alkylating agents
AML not otherwise categorised

**Myeloid neoplasms with germline predisposition
**- Myeloid neoplasm without a pre-existing disorder or organ dysfunction (germ line CEBPA, DDX41)
- Myeloid neoplasm with pre-existing platelet disorder - germ line RUNX1, ANKRD26, ETV6
- Myeloid neoplasm with other organ dysfunction - germline GATA2, BM failure syndromes (Fanconi anaemia, dyskeratosis congenita), Down Syndrome, Li Fraumeni syndrome (TP53)

• Relevant as family may act as bone marrow transplant donors

Question 5

General principles AML management

Answer 5

Intensive induction chemotherapy to achieve remission = 7+3
- cytarabine continuous infusion 7days + 3 days anthracycline (daunorubicin r idarubicin)
Supportive care for severe bone marrow failure
- Transfusion support
- Infection prophylaxis (posaconazole)
- Nutrition
- Psychological
- Management of febrile neutropaenia
- Management of bleeding

Question 6

Notes on midostaurin used in AML induction treatment

Answer 6

• FLT3 mutation - most units will try identify this mutation via rapid PCR in first few days of diagnosis AML
• FLT 3 = membrane bound protein kinase - mutations can be in the juxtamembrane domain or tyrosine kinase domain
• If either mutation positive -> midostaurin at induction therapy -> survival advantage

Question 7

Favourable and non-favourable features post-induction chemotherapy and pathway to cure

Answer 7

Consolidation chemo = cytarabine
MRD = minimal residual disease testing

**Unfit for intensive chemotherapy
**Age >= 75 or Age >= 60 with organ dysfunction (ECOG 2-3, LVEF <50%, DLCO <65%, CrCl <45)
Palliation to maintain quality of life
Low dose chemotherapy - cytarabine, venetoclax + cytarabine, or azacitidine
Targeted therapies - IDH mutation
Supportive care: blood transfusions and antibiotics

Question 8

Adverse clinical predictors in AML

Answer 8

1. Age - most important
2. Poor performance status
3. Cytogenetic and/or molecular genetic findings in tumour cells
4. History of prior exposure to cytotoxic agents or radiation therapy
5. History of prior myelodysplasia or other haematologic disorders such as myeloproliferative neoplasms

1-2: main predictors early death
3-5: predictors of resistant disease or early relapse

Question 9

Notes on acute promyelocytic leukaemia

Answer 9

Considered medical emergency
Characteristic morphology of the cell -> prominent granulation and Auer rods
Rapidly fatal sub-type -> severe bleeding complications related to disseminated intravascular coagulation
Rapid diagnosis with PML-RARA PCR or FISH. Karyotype demonstrates t(15;17)
Ugent control of DIC - platelet transfusion and fibrinogen replacement is important
Differentiation therapy with ATRA plus arsenic
- ATRA = modified Vitamin A derivative
- May produce a syndrome characterised by fever, oedema and weight gain, hypoxia with lung infiltrates, pleuropericardial effusion, renal and hepatic dysfunction - commence dexamethasone 10mg BD and consider delaying chemotherapy
- should stop ATRA if severe, usually can restart

Good prognosis

Question 10

Notes on age-related clonal haemopoiesis (CHIP)

Answer 10

Acquired somatic mutations occur in the blood of haematologically normal individuals with aging
Study of 17,000 individuals analysed -> mutations in DNMT3, TET2, ASXL1, TP53
11 fold increased risk of haematological cancer. Increased risk of cardiovascular disease

Question 11

Diagnosis of myelodysplastic syndrome

Answer 11

CBC = pancytopaenia. Tends to be onset over months in terms of symptoms
Bone marrow biopsy
1. MDS with single lineage dysplasia - blasts <5% +/- with ring sideroblasts
2. MDS with multilineage dysplasia - blasts <5% with ring sideroblasts
3. MDS with excess blasts (5-19%)
4. Isolated del)5q) abnormality

Some rare disorders that have features of myelodysplastic and myeloproliferative
1. Chronic myelomonocytic leukaemia - blood monocytes >1, <20% blasts
2. Juvenile myelomonocytic leukaemia - RAS point mutations, NF-1 mutation

Question 12

Prognostication in MDS

Answer 12

**Sequelae of low-risk MDS
**84% die of MDS related complications -> infection (most common), progression to AML, haemorrhage, disease progression

Question 13

Management of MDS

Answer 13

**Low risk
**Maintain quality of life - usually an elderly population receiving supportica therapy only
Red cell transfusion, platelet transfusion/TXA, antibiotics
Consider iron chelation after 20 units of red cells
Medalist Trial -> Luspatercept (activin type IIB receptor fusion protein that regulates late stage erythropoiesis) reduces red cell transfusion requirements

**High risk
**active treatment aimed at changing the natural history of disease
Azacitidine - improved overall survival, delayed transformation to AML, improves cytopaenias. Requires mutliple treatment cycles (typically 4 months therapy)
Allogenic BM transplant considered in younger patients

**Targeted therapy
**5q syndrome - marked response to lenalidomide
Hypoplastic anaemia, normal or elevated platelet count, atypical marrow megakaryocyte with relatively indolent clinical course

Question 14

Definition of chronic myeloid leukaemia

Answer 14

Myeloproliferative neoplasm of blood stem cell origin characterised by chromosomal translocation t(9;22)
Results in formation of the Philadelpia chromosome & BCL-ABL fusion gene
- Routinely seen on metaphase cytogenetics or FISH
Major proliferative component is myeloid precursor expansion in the bone marrow and blood
Cryptic and variant forms of the Philadelphia chromosome can occur

Question 15

Blood film in CML

Answer 15

Leucocytosis with left shift, presence of basophils

Question 16

Epidemiology, and natural history of CML

Answer 16

Relatively rare, 1/100,000
Rare in children, median age at diagnosis 57-60 years
Slight male predominance
Prevalence likely to increase in coming years due to improved survival
Aetiology unknown - ionising radiation only established risk factor (has been linked to atomic bomb survivors)
No known familial aggregation
Natural history untreated -> biphasic or triphasic. Chronic phase can be asymptomatic or associated with constitutional symptoms/splenic pain. Untreated neoplasm will eventually transform into accelerated/blastic phase -> progressive constitutional symptoms/splenomegaly and bone marrow failure
- Risk of transformation in untreated chronic phase = 20-25% per years
- Acute transformation can be myeloid or lymphoid

Question 17

Presentation of CML

Answer 17

Classical -> constitutional symptoms, marked splenomegaly and elevated white cell count.
- Now uncommon in Western societies due to frequency of blood tests
- Many diagnosed incidentally or with minimal symptoms/signs based on leukocytosis/left shift
- Occasionally the main haematology abnormality is of prominent thrombocytosis
- Very rarely present in blast crisis

Question 18

Work-up for CML

Answer 18

Physical exam, document liver and spleen size
FBC and differential, biochemistry and ECG
Bone marrow biopsy for morphology - distinguish chronic phase from accelerate phase/blast crisis and perform cytogenetics for Philadelphia chromosome (FISH analysis if Philadelphia chromosome negative)
Qualitative/quantitative BCR-ABL RT-PCR wither on blood or bone marrow

Question 19

Therapy and monitoring in CML

Answer 19

**Goals
**Normal survival and good quality of life
Attainment of treatment free remission
Requires regular monitoring by quantitative RT PCR in peripheral blood

**First line therapy
**TKI (except in pregnancy) -> imatinib, nilotinib, dasatinib
Second generation agents dasatinib and nilotinib have been trialled against imatinib but not eachother

**Imatinib
**Improved progression free survival and overall survival compared to chemotherapy (standard therapy 20 years ago)
Side effects -> fluid retention, muscle pain, GI issues, skin rash, fatigue. Symptoms can improve over time. 400mg PO daily
Dasatinib -> 2nd generation more potent, more rapid and deeper molecular responses. Similar PFS and OS to imatinib. Side effects -> pleural effusion and rarely pulmonary hypertension
Nilotinib -> same as dasatinib except for side effects -> increased risk CVS events and pancreatitis

**Second line therapy
**Resistance can be due to mutations in the bcr-abl kinase domain - mutations can give guidance on further therapy
315I most resistant mutation -> ponatinib (third generation) or asciminib
Intolerance -> switch to other agent in 1st line therapy list

Question 20

Notes on ponatinib and asciminib

Answer 20

**Ponatinib
**Third generation TKI
Approved for T315I BCR-ABL mutations or resistance to >=TKI agents
Associated with significant risk CVS events

**Asciminib
**Novel allosteric inhibitor of BCR-ABL
Binding site not in kinase domain
FDA approval in CML resistant to two or more TKI including patients with T315I mutation
Side effects -> pancreatitis, fatigue, nausea, headaches

Question 21

Notes on treatment free remission in CML

Answer 21

40-50% achieve this
Vast majority of patients who progress after stopping do so within first 6-9 months.
Long term molecular monitoring required

Question 22

Role of allogenic BMT

Answer 22

1. Small number whose illness is resistant to second generation agents +/- Ponatinib/asciminib
2. Patients who present in blast crisis with subsequent achievement of second chronic phase

Question 23

Management of CML in pregnancy

Answer 23

TKIs potentially teratogenic - not recommended at all in any stage in pregnancy
Options -> observation alone, use of alpha-interferon
Males prescribed TKIs - no increased risk of congenital malformations in offspring

Question 24

Notes on HPSC differentiation