3. CML and myeloproliferative disorders Flashcards
(92 cards)
1
Q
What is polycythaemia characterised by?
A
Polycythaemia is a condition that is characterised by a raised Hb concentration and raised haematocrit
2
Q
What is relative polycythaemia?
A
caused by a lack of plasma (non-malignant) (rather than an increase in erythrocytes)
3
Q
What increases the risk of relative polycythaemia?
A
Alcoholism, obesity and the use of diuretics
4
Q
What is true polycythaemia?
A
Excess of erythrocytes
5
Q
What does secondary (non-malignant) polycythaemia occur as a response to?
A
In response to increased EPO. In secondary polycythaemia, the bone marrow is normal and healthy, however, it is being stimulated by excess EPO.
6
Q
What are causes of appropriately raised eythropoietin?
A
High altitude, hypoxic lung disease, cyanotic heart disease, high affinity haemoglobin
7
Q
What are causes of inappropriately raised eythropoietin?
A
Renal disease (cysts, tumours, inflammation), uterine myoma, other tumours (liver, lung)
8
Q
What are types of true polycythaemia?
A
Secondary (non-malignant) in response to increased EPO, and primary (myeloproliferative neoplasm)
9
Q
What are myeloproliferative neoplasms that are Philadelphia negative?
A
Polcythaemia vera (PV), essential thrombocythaemia (ET), primary myelofibrosis (PMF)
10
Q
What are myeloproliferative neoplasms that are Philadelphia positive?
A
Chronic myeloid leukaemia (CML)
11
Q
As cells develop they undergo TWO processes:
A
Differentiation and proliferation
12
Q
What happens to differentiation and proliferation in chronic myeloid leukaemia?
A
You get increased proliferation of the myeloid cells but they maintain the ability to fully differentiate into mature cells
13
Q
What happens to differentiation and proliferation in acute leukaemias?
A
In acute leukaemias, the same issue of overproduction of cells is present, however, they have undergone an extra biological change which is catastrophic. They have lost the ability to differentiate and mature so the bone marrow gets filled up of precursor cells.
14
Q
What are examples of myeloid haematological malignancies?
A
Acute myeloid leukaemia, myelodysplasia, myeloproliferative disorders, chronic myeloid leukaemia
15
Q
What are the percentages of blasts in AML?
A
blasts > 20%
16
Q
What are the percentages of blasts in myelodysplasia?
A
blasts 5-19%
17
Q
What are lymphoid haematological malignancies with precursor cell malignancy?
A
Acute lymphoblastic leukaemia (B and T cell)
18
Q
What are lymphoid haematological malignancies with mature cell malignancy?
A
Chronic lymphocytic leukaemia, multiple myeloma, lymphoma (Hodgkin & Non-Hodgkin)
19
Q
What is the difference between myeloid and lymphoid?**
A
The main difference between myeloid and lymphoid cells is that myeloid cells give rise to red blood cells, granulocytes, monocytes, and platelets whereas lymphoid cells give rise to lymphocytes and natural killer cells**
20
Q
What processes are disrupted by mutation in myeloproliferative disorders?
A
Cellular proliferation (type 1), impair/block cellular differentiation (type 2) and prolong cell survival (Anti-apoptosis)
21
Q
What are some mutation mechanisms?
A
DNA point mutations and chromosomal translocations, including creation of novel fusion gene and disruption of proto-oncogene
22
Q
What are the main types of mutations that leads to cellular proliferation?
A
Tyrosine kinase mutations
23
Q
What is the role of tyrosine kinases?
A
- Transmit cell growth signals from cell surface receptors to the nucleus.
- Activated by transferring phosphate groups to self and downstream proteins
- Normally held tightly in inactive state
- Promote cell growth but do NOT block maturation
24
Q
If a mutation activates a tyrosine kinase gene, what will it result in?
A
It will result in an expansion of mature cells
25
In which type of disorder do you get increased proliferation but differentiation is normal?
Myeloproliferative disorders
26
With primary myelofibrosis you have an expanded clone of myeloid haemopoiesis in the bone marrow which is followed by?
Aggressive and reactive fibrosis of the bone marrow
27
What are some MPD-associated gene mutations?
JAK2, calreticulin, and MPL
28
In polycythaemia vera, which gene(s) are mutated and in what percentage of cases?
JAK2 undergoes a single point mutation (V617F) in 100% of cases of polycythaemia vera
29
In essential thrombocytopenia, what gene(s) are mutated and in what percentage of cases?
JAK2 V617F (60%), calreticulin (30%), MPL (5%)
30
In primary myelofibrosis, what gene(s) are mutated and in what percentage of cases?
JAK2 V617F (60%), calreticulin (30%)
31
What myeloproliferative disorders is the JAK2 mutation found in?
Polycythaemia vera, essential thrombocythaemia, primary myelofibrosis
32
What activates the JAK2 signalling pathway resulting in the normal response to EPO?
JAK2 is normally bound to the inactive EPO receptor. When EPO binds to the EPO receptor, the receptor dimerises and autophosphorylates and phosphorylates JAK2.
33
In the case of JAK2 mutation, what happens to the JAK2 signalling pathway?
In the case of JAK2 mutation, the JAK2 signalling pathway is constitutively active so you get an EPO response even in the absence of EPO
34
In what myeloproliferative disorders is calreticulin mutations found in?
In some cases of ET and PMF
35
How are myeloproliferative disorders diagnosed?
Based on a combination of clinical features (symptoms, splenomegaly), FBC+/- bone marrow biopsy, EPO level, mutation testing (phenotyping linked to acquired mutation)
36
Who is polycythaemia more common in?
Slightly more common in males
37
What is the mean age of diagnosis for polycythaemia vera? (What percentage get diagnosed before age of 40?)
60 years. 5% below the age of 40 yrs
38
What is the clinical presentation of polycythaemia vera?
Often an incidental finding on a routine FBC.
There will be symptoms of viscosity such as: headaches, light-headedness, stroke, visual disturbances, fatigue, dyspnoea.
Increased histamine release results in aquagenic pruritis and peptic ulceration.
39
What are the principles of treatment of PV?
Aim to reduce HCT (target HCT < 45%) and aim to reduce risk of thrombosis
40
How is PV managed?
To reduce HCT: venesection (tends to be only suitable in younger/healthier patients), cytoreductive therapy (hydroxycarbamide). To reduce risk of thrombosis: control HCT, aspirin, keep platelets < 400 x 10^9/L
41
What is essential thrombocythaemia?
Chronic myeloproliferative disorder mainly involving the megakaryocytic lineage
42
What parameter suggests essential thrombocythaemia?
Sustained thrombocytosis > 600 x 10^9/L
43
At what age do people tend to get essential thrombocythaemia? And what is the F:M ratio?
Bimodal age distribution: 20 years (minor peak), 55 years. Females: males are equal in the first peak and predominate the second peak
44
What is the clinical presentation of essential thrombocythaemia?
- Incidental finding on FBC (50% of cases)
- Thrombosis (arterial or venous), presenting as: cerebrovascular accident, gangrene, TIA, DVT, PE.
- Bleeding: mucous membrane and cutaneous. Platelets are abnormal but hard to describe its functionality
- Headaches, dizziness, visual disturbances
- Splenomegaly (modest)
45
What are the platelets like in essential thrombocythaemia?
The platelets in ET are functionally abnormal, however, this functionality can be difficult to describe. In some cases they will be predisposed to activation and thrombosis, whereas in other cases it can lead to increased bleeding.
46
What is the treatment for essential thrombocythaemia?
Aspirin (thrombosis prevention), hydroxycarbamide (antimetabolite that suppresses cell turnover/cytoreductive therapy), anagrelide (specifically inhibits platelet formation but NOT commonly used due to side-effects of palpitations and flushing)
47
What is the prognosis of essential thrombocythaemia?
Normal life span in many patients. Leukaemic transformation in about 5% over 10 years. Myelofibrosis is also UNCOMMON, unless there is fibrosis at the beginning
48
What is the definition of primary myelofibrosis?
A clonal myeloproliferative disease associated with reactive bone marrow fibrosis
49
What is primary myelofibrosis characterised by?
Extramedullary haematopoiesis
50
Who does primary myelofibrosis tend to present in and at what age?
Tend to present around 60-70 yrs, males = females
51
Other myeloproliferative disorders may transform into PMF, true or false?
True
52
What is the clinical presentation of primary melofibrosis?
Incidental in 30%. Presentations related to: cytopaenias (anaemia, thrombocytopaenia), thrombosis, splenomegaly (MASSIVE) - Budd-Chiari syndrome, hepatomegaly, hypermetabolic state (weight loss, fatigue and dyspnoea, night sweats, hyperuricaemia).
53
What is useful in the diagnosis of PMF?
blood film. bone marrow, liver and spleen, DNA
54
What does a blood film look like in PMF?
Leucoerythroblastic picture, tear drop poikilocytes, giant platelets, circulating megakaryocytes
55
How can bone marrow be tested for PMF?
Dry tap.
Trephine biopsy: uncreased reticulin or collagen fibrosis, prominent megakaryocyte hyperplasia and clustering abnormalities, new bone formation
56
How can the liver and spleen indicate PMF?
Extramedullary haematopoiesis
57
How can DNA indicate PMF?
JAK2 or calreticulin mutation
58
What is the prognosis of PMF?
Median 3-5 years survival but is very variable
59
What are BAD prognostic signs of PMF?
Severe anaemia < 100 g/L, thrombocytopaenia < 100 x 10^9/L, massive splenomegaly. (Prognostic scoring system is called DIPPS)
60
What is the treatment for primary myelofibrosis?
Very limited.
- Supportive: RBC and platelet transfusion often ineffective because of splenomegaly (leads to rapid breakdown of transfused red cells)
- Cytoreductive therapy: hydroxycarbamide (for thrombocytosis, may worsen anaemia)
- Ruxolotinib: JAK2 inhibitor, only used in high prognostic score cases
- Allogenic stem cell transplantation: potentially curative, reserved for high risk eligible cases
- Splenectomy: may offer symptomatic relief, dangerous operation, often followed by worsening of condition
61
Who does chronic myeloid leukaemia tend to present in and at what age?
More common in MALES, average age at presentation: 40-60 yrs
62
What is a risk factor for CML?
Radiation exposure
63
What is the chromosomal abnormality in CML?
The swapping of DNA between the chromosomes leads to the formation of a new gene (an oncogene) called BCR-ABL
64
What was the first disease to have a targeted orally active drug that was directed against the mutated TK?
CML
65
How does CML present?
```
o Lethargy
o Hypermetabolism
o Thrombotic event
o Mono-ocular blindness
o CVA
o Bruising
o Bleeding
o Massive splenomegaly/hepatomegaly
```
66
What is the FBC in CML?
Hb and platelets are normal or raised; MASSIVE leucocytosis (50-500 x 109/L)
67
What can be seen in the blood film for CML?
Neutrophils, myelocytes (NOT blasts), basophilia
68
Summarise the laboratory features of CML
Leucocytosis (50-500 x 10^9/L), mature myeloid cells, biphasic peak in neutrophils and myelocytes, basophilia, NO excess myeloblasts (<5%), platelet count raised/upper normal
69
What is the natural course of CML (before imatinib)?
- There is the chronic phase and advanced phase
- During the first 5-6 years, the disease will be in a 'chronic phase' where the cells will proliferate but they maintain the ability to differentiate into mature cells
- The advanced phase: eventually, an additional mutation will result in the inability of cells to fully differentiate. This results in an increasing proportion of blasts. This phase led to death very quickly.
- The advanced phase has an accelerated phase (10-19% blasts) which has a median duration of 6-12 months)
- This leads to the blast crisis (>20% blasts) which has a median survival of 3-6 months.
70
What chromosomal translocation does CML arise from?
CML arises from a chromosomal translocation between chromosomes 9 and 22. The derivative chromosome 22q is also known as the Philadelphia chromosome
71
Translocation occurs at the introns of which two genes?
Bcr (breakpoint cluster region) and Abl (ableson tyrosine kinase)
72
What does the fusion gene BCR-ABL code for?
Tyrosine kinase
73
What happens when transcription factors read along the DNA of Philadelphia?
If a transcription factors reads along the DNA of the Philadelaphia chromosome, it will go across several BCR exons followed by ABL exons. This will result in the formation of mRNA which contains a 5' portion of the BCR gene and a 3' portion of the ABL gene
74
What drives cell replication in cells containing the Philadelphia chromosome, in terms of the BCR-ABL fusion gene being expressed?
ABL is a tyrosine kinase, and, normally, we do not express high levels of tyrosine kinase in the body (they only tend to be active in cells that are receiving a stimulus to proliferate). However, BCR is a housekeeping gene that is constitutively expressed. This results in the BCR-ABL fusion gene being constitutively expressed and constitutively activated.
75
What are diagnostic techniques to identify the fusion gene in CML?
Conventional karyotyping, FISH metaphase or interphase karyotyping. RT-PCR amplification and detection
76
What are ways of diagnosing CML and monitoring response?
- FBC and leucocyte count
- Cytogenetic and detection of Philadelphia chromosome
- RT-PCR can be used to quantify the BCR-ABL fusion transcript
- This can help determine the response to therapy
(There are also diagnostic techniques to identify the fusion gene)
77
What is CML managed?
Commence on oral 1st generation tyrosine kinase inhibitor. Monitor response using FBC, cytogenetic, RQ-PCR.
78
What is the average 5-year mortality of CML?
95%
79
What is the annual mortality of CML?
2%
80
What are the issues with tyrosine kinase inhibitors?
Some people fail to achieve a complete cytogenetic response (CCyR); non-compliance; side-effects (fluid retention, pleural effusion); loss of major molecular response; acquisition of ABL point mutations leads to treatment resistance; evolution of a blast crisis
81
When assessing response and monitoring therapy in CML, what suggests complete haematological response?
WBC < 10x10^9/L
82
When assessing response and monitoring therapy in CML, what shows a cytogenetic response (on 20 metaphases)?
Partial cytogenic response = 1-35% Philadelphia positive
Complete cytogenic response = 0% Ph positive
83
When assessing response and monitoring therapy in CML, what shows a molecular response? ***
If BCR-ABL transcripts reduce 100% > 10% > 1% > 0.1%.
Major Molecular response (MMR) <0.1% (3 log reduction).
84
What is the most sensitive assessment of response in CML?
Looking at transcripts (including haematological, cytogenetic, and molecular response)
85
What are examples of chronic phase tyrosine kinase inhibitors?
1st gen - Imatinib. 2nd gen - Dasatinib, Nilotinib. 3rd gen - Bosutinib
86
What do to if CML doesn't respond to chronic phase tyrosine kinase inhibitor 1st gen therapies (failure 1)? When is it considered a failure?
Switch to 2nd gen or 3rd gen tyrosine kinase inhibitor.
Considered a failure if there is NO complete cytogenetic response at 1 year OR if they respond but acquire resistance
87
What do to if CML doesn't respond to chronic phase tyrosine kinase inhibitors (failure 2)? When is it considered a failure?
Consider allogeneic stem cell transplantation.
Considered a failure if the is an inadequate response to 2nd generation tyrosine kinase inhibitors OR if the disease progresses to accelerated or blast phase.
88
Clinical case 1: 53 y/o male with weight loss and abdo discomfort. O/E hepatomegaly and spleen 6cm below costal margin. Hb 98g/L; WBC 20x10^9/L; platelets 60x10^9/L. BCR-ABL transcripts not detected. JAK2 V617F 20%. BM aspirate dry tap. Blood film shows poikilocytes (and nucleated red blood cells??). What is the diagnosis?
Primary myelofibrosis
89
What is dry tap?
"Dry tap" is a term used to describe failure to obtain bone marrow on attempted marrow aspirations.
90
What causes dry tap?*
Extensive marrow fibrosis and hypercellularity have been proposed as mechanisms to account for the inability to withdraw marrow by aspiration. Seen in PMF
91
Clinical case 2: 22 y/o male, cyanotic congenital heart disease, Hb 210g/L and haematocrit 60%. No splenomegaly. Select the most likely lab results:
Serum erythropoietin, JAK2 mutation analysis.
(Likely to be secondary polycythaemia (non-malignant) due to congenital heart problem, but must rule out PV and other MPDs)****
92
Clinical case 3: 35 year old woman with CML on Tx with Imatinib. Results on diagnosis: Hb (g/L) = 16; WCC (x10^9/L) = 300; platelets (x10^9/L) = 800; blasts = 2%; BCR-ABL = 100%. Results at 12 months: Hb (g/L) = 13; WCC (x10^9/L) = 8.5; platelets (x10^9/L) = 320; blasts = 0%; BCR-ABL = 0.01%. Results at 24 months: Hb (g/L) = 9; WCC (x10^9/L) = 35; platelets (x10^9/L) = 24; blasts = 25%; BCR-ABL = 10%
Patient has acquired resistance to Imatinib, treatment is failing. Blasts are high, potential blast crisis. Switch to Dasatinib. ***
