CML and Myeloproliferative Disorders Flashcards
What is polycythaemia?
Raised Hb conc. + Haematocrit %
What are causes of polycythaemia?
Relative: Lack of plasma = Non-malignant (Pseudo)
True: Excess erythrocytes
Primary: Myeloproliferative neoplasm
Secondary: Non-malignant
What are the classes of myeloproliferative neoplasms? Give examples of each
Ph (Philadelphia Chr) -ve:
- Polycythaemia vera (PV) (erythroid)
- Essential Thrombocythaemia (ET) (megakaryocytic)
- Primary Myelofibrosis (PMF)
Ph +ve:
- Chronic myeloid leukaemia (CML)
What are dilution studies used for?
To differentiate between true + relative polycythaemia
Red Cell Mass: 51 Cr labelled RBC
Plasma Vol: 131 I labelled albumin
What are 3 causes of relative/pseudo-polycythaemia?
Alcohol
Obesity
Diuretics
What happens to EPO in primary and secondary true polycythaemia?
Primary: Reduced
Secondary: Elevated
What are 4 appropriate causes of elevated EPO?
High altitude
Hypoxic lung disease
Cyanotic heart disease
High affinity haemoglobin
What is the mechanism behind appropriate raise in EPO?
Low O2 tension detected by kidneys
Stimulates raise in EPO
Increases Hb production
How do lung, heart and high affinity haemoglobin cause appropriate increase in EPO?
Hypoxic lung disease: Less gas exchange, less O2 reaches kidneys
Cyanotic heart: Sending deoxygenated blood to kidneys
High affinity Hb e.g. Sickling thalassemia- fail to release O2 from Hb at lower O2 tensions, starve tissue of O2
What are 3 inappropriate causes of elevated EPO?
Renal disease (cysts, tumours, inflammation)
Uterine myoma
Other tumours (liver, lung)
What are examples of lymphoid haematological malignancies?
Precursor cell malignancy: ALL (B + T)
Mature cell malignancy: CLL, Multiple myeloma, Lymphoma (Hodgkin + Non Hodgkin)
What are 3 types of myeloid haematological malignancies?
Acute myeloid leukaemia (blasts >20%)
Myelodysplasia (blasts 5-19%)
Myeloproliferative disorders: ET, PV, PMF, CML
Which 3 processes in blood cancers are disrupted by mutation?
Cellular proliferation (type 1)
Impair/ block cellular differentiation (type 2)
Prolong cell survival (anti-apoptosis)
What is the normal function of tyrosine kinases?
Transmit cell growth signals from surface receptors to nucleus.
Activated by transferring phosphate groups to self + downstream proteins.
Normally held tightly in inactive state.
Promote cell growth, do not block maturation.
What happens when mutations cause activation of tyrosine kinase?
Expansion increase in mature/ end cells
Red cells: Polycythaemia
Platelets: Essential thrombocythaemia
Granulocytes: Chronic myeloid leukaemia
What occurs when EPO receptor binds erythropoietin?
Changes configuration of TK receptor
Phosphorylates JANUS Kinase 2 - ACTIVE
Able to pass phosphate groups to downstream signalling molecules which take the signal from the bound receptor to the nucleus to drive proliferation
Which genes are associated with myeloproliferative neoplasms?
JAK2 (100% of PV, 60% of ET + PMF)
Calreticulin
MPL
How is the diagnosis of myeloproliferative disorder (Ph negative) made?
Clinical features: Sx + Splenomegaly
FBC +/- BM biopsy
Erythropoietin level (EPO)
Mutation testing: Phenotype linked to acquired mutation
What is the epidemiology of polycythaemia vera?
Annually: 2-3/100,000
M > F = 1.2 : 1
Mean age dx: 60y
5% < 40y
How does PV present clinically? How is it diagnosed?
Incidental dx routine FBC (median Hb 184g/l, Hct 0.55).
Sx of increased hyper viscosity
Sx due to increased histamine release
Test for JAK2 V617F mutation
List 6 symptoms caused by blood hyper viscosity in PV
Headaches
Light-headedness
Stroke
Visual disturbances
Fatigue
Dyspnoea
Give 2 symptoms caused by increased histamine release in PV
Aquagenic pruritis
Peptic ulceration
How is PV treated?
Aim to reduce HCT: Target HCT <45%
Aim to reduce risks of thrombosis
Give 2 ways in which HCT can be reduced in PV?
Venesection
Cytoreductive therapy hydroxycarbamide
How do we reduce the risk of thrombosis in PV?
Control HCT
Aspirin
Keep platelets < 400x10^9/l
What is essential thrombocythaemia?
Chronic MPN mainly involving megakaryocytic lineage.
Sustained thrombocytosis >600x10^9 /L.
Incidence: 1.5 per 100000.
2 peaks: 55y + minor peak 30y
F : M = Equal 1st peak but F predominate 2nd peak.
What is the presentation of essential thrombocythaemia?
Incidental finding on FBC (50% cases).
Thrombosis: Arterial: CVA, gangrene, TIA OR venous: DVT or PE.
Bleeding: Mucous membrane + cutaneous.
Headaches, dizziness, visual disturbances.
Splenomegaly (modest).
What is the treatment of essential thrombocythaemia?
Aspirin: To prevent thrombosis.
Hydroxycarbamide: Antimetabolite. Reduces platelet count, suppression of other cells as well.
Anagrelide: Specific inhibition of platelet formation, SE: palpitations + flushing.
What is the prognosis of essential thrombocythaemia?
Normal life span, may not be changed in many
Leukaemic transformation in ~5% after >10 years.
Myelofibrosis also uncommon, unless there is fibrosis at the beginning.
What is primary myelofibrosis?
Clonal myeloproliferative disease associated with reactive BM fibrosis.
Extramedullary haematopoieisis.
Incidence 0.5-1.5 /100,000
M = F
7 th decade: Less common in young
Other MPDs (ET + PV) may transform to PMF
What is the clinical presentation of primary myelofibrosis? How is it diagnosed?
Incidental in 30%
Presentations related to:
Cytopenias: Anaemia/ thrombocytopenia
Thrombocytosis
Splenomegaly: May be massive.
Hepatomegaly +/- Budd-Chiari syndrome
Sx of Hypermetabolic state
What symptoms may be seen due to hyper metabolic state in PMF?
Weight loss
Fatigue
Dyspnoea
Night sweats
Hyperuricaemia
What are findings of primary myelofibrosis on a blood film?
Leucoerythroblastic picture
Tear drop poikilocytes
Giant platelets
Circulating megakaryocytes
What are findings of primary myelofibrosis in the bone marrow?
‘Dry tap’
Trephine:
- Increased reticulin or collagen fibrosis
- Prominent megakaryocyte hyperplasia + clustering with abnormalities
- New bone formation
What are additional findings of primary myelofibrosis?
Liver + spleen: Extramedullary haemopoiesis
DNA: JAK2 or CALR mutation
What is the prognosis of primary myelofibrosis?
Median 3-5 years but very variable
What are bad prognostic signs of primary myelofibrosis?
Severe anaemia <100g/L
Thrombocytopenia <100x109 /l
Massive splenomegaly
Which prognostic scoring system can be used for primary myelofibrosis?
Prognostic scoring system (DIPPS):
Score 0: Median survival 15 years
Score 4-6: Median survival 1.3 years
What is the limited range of treatment options for primary myelofibrosis?
Supportive: RBC + platelet transfusion often ineffective because of hypersplenism
Cytoreductive therapy: Hydroxycarbamide (for thrombocytosis (suppresses clones), may worsen anaemia).
Ruxolotinib: JAK2 inhibitor (high prognostic score cases)
Allogeneic SCT: Potentially curative reserved for high risk eligible cases.
Splenectomy for symptomatic relief: Hazardous + often followed by worsening of condition.
What is CML?
Ph +ve myeloproliferative neoplasia.
Incidence 1-2/100,000
M > F = 1.4 : 1
40-60y
RF= Radiation exposure
What are clinical signs of CML?
Lethargy/ Hypermetabolism/ Thrombotic event: Monocular blindness, CVA, bruising, bleeding.
Massive splenomegaly +/- hepatomegaly
What can be seen in terms of bloods for CML?
FBC: Hb + platelets well preserved or raised
Massive leucocytosis 50-200x109 /L
Blood film: Neutrophils + myelocytes (not blasts if chronic phase)
- Basophilia
What are laboratory findings for CML?
Leucocytosis: 50 – 500x10^9 /l
Mature myeloid cells
Biphasic peak: Neutrophils + myelocytes
Basophils
No excess (<5%) myeloblasts
Platelet count raised/ upper normal (contrast acute leuk)
Which translocation produces the Ph chromosome?
t(9;22)
BCR-ABL
How does BCR-ABL contribute to myeloproliferative neoplasms?
Expresses a fusion oncoprotein with constitutive tyrosine kinase activity.
Drives myeloid proliferation.
Which available diagnostic techniques can be used to identify the translocation/fusion?
Conventional Karyotyping
FISH metaphase or interphase karyotyping
RT-PCR amplification + detection
How are myeloproliferative diseases and their responses monitored?
FBC + measure leucocyte count.
Cytogenetics + detection of Philadelphia chr.
RT-PCR of BCR-ABL fusion transcript which can be quantified by RQ-PCR to determine response to therapy.
What was the clinical course of CML before Imatinib?
Chronic phase: Median 3-4 years duration
Accelerated phase (10-19% blasts): Median duration 6–12 months
Blast crisis (>20% blasts): Median survival 3–6 months
What is the treatment of CML in the chronic phase?
- Tyrosine kinase Inhibitor (TKI): Imatinib (1Gen,) Dasatanib, Nilotonib (2G), Bosutinib (3G)
2. Failure (1) > Switch to 2Gen or 3G TKI:
No complete cytogenetic response at 1y or Respond but acquire resistance
3. Failure (2) > Consider allogeneic SCT
Inadequate response or intolerant of 2G TKIs
or Progression to accelerated or blast phase
How do myeloproliferative neoplasms and acute leukaemia differ with respect to differentiation?
M: no impairment of differentiation, excess proliferation
AL: mutations block differentiation, excess proliferation
What are the mutation mechanisms in blood cancer?
DNA point mutations
Chromosomal translocations: Creation of novel fusion gene/ Disruption of proto-oncogene
What is monitored throughout treatment of CML?
FBC
Cytogenetics
RQ-PCR
CCyR at 1y (Complete cytogenetic response = 0% Ph +ve metaphases)
What is the prognosis for CML?
97% FFP at 6y (freedom from progression)
95% 5y survival
2% Annual mortality
What are the disadvantages of TKIs?
Failure to achieve CCyR
Non-compliance
SE: Fluid retention, pleural effusions
Loss of major molecular response (MMR): Acquiring ABL point mutations leading to resistance, evolution to blast crisis