Myeloproliferative Neoplasms Flashcards
name the types of myeloproliferative anaemia and the gene change that causes them
- Chronic myelogenous leukaemia, BCR-ABL1- Positive (CML)
- Polycythaemia vera – JAK2 variation
- Essential thrombocythemia – CALR exon 9
- Primary myelofibrosis – CALR exon 9
describe how CML is caused
- CML – was the first malignancy where there was a genetic basis of understanding made - Philadelphia chromosome – found in analysing patients with CML – found that the translocation was present
- Part of chromosome 22 is broken of and attached to chromosome 9
- Get an extra long chromosome 9 and short chromsoem 22 (philadephia chromosome)
- As a result of this translocation a new gene was found on chromosome 22 BCR is present on chromosome 9 ABL is found
- When chromosome 22 and 9 join you get BCR-ABL – codes for a new protein which is a trysoine kinase – this is an enzyme which attach a phosphate from ATP onto a protein, they are molecular on and off switches – switched on and not switched off
- Led to the development of targeted therapy
name what can be used to treat CML
- Imatinib can be used to treat CML
What is CML characterised by
- Characterised by dysregulated and uncontrolled proliferation of mature and maturing granulocytic cells
By definition what does CML have to have
- By definition has to have the presence of T(9,22), the Philadelphia chromosome
What does the blood film of CML have to have
- Increased granulocyte seen at all phases of maturation
- Lots of neutrophils
- Myelocytes – cells that are on there way to developing neutrophils
- Basophils
What are the symptoms of CML
- Many asymptomatic
- B symptoms – fatigue, weight loss, night sweats
Systemic symptoms
- Fatigue
- Night sweats
- Malaise
- Weight loss
Splenomegaly – particular in CML
- Early satiety – compress on the stomach
- Left Upper Quadrant fullness/pain
Hyperviscosity - particular in CML
- Headache
- Blurred vision
- Fluid overload
- Thrombosis and haemorrhage
How do you diagnose CML
- FBC
- Blood film
- Bone marrow biopsy
- Chromsome G banding
- FISH
- reverse transcriptase qPCR
- Nap/LAP score
what would the different ways of diagnosing CML show
- FBC
- Blood film
- Bone marrow biopsy
- Chromsome G banding
- FISH
- reverse transcriptase qPCR
- Nap/LAP score
- FBC = Raised White cell count and basophilia
- Blood film
- Bone marrow biopsy – blasts
- Chromosome G banding – karyotype is determined – presence of the philidephalia chromosome
- FISH – presence or absent of the BCR-ABL gene – take a probe which is commercialy available that will bind to the ABL gene on chromosome 9 and BCR gene on chromosome 22 – under flourscent light it wil light up a certain colour – normally genes are not in close proximity so the two different lights (red and green) are separate but if the fusion gene is present the lights are together and you see yellow light
- Reverse Transcriptase qPCR – amplify the copies of the BCR-ABL gene and you will be able to monitor how much gene is present so you can treat them
- Nap/LAP score - - level of leuckocyte alkaline phosphatase (LAP) will be decreased
What is the Philadelphia chromosome
The Philadelphia chromosome (Ph) is the hallmark of chronic myeloid leukaemia (CML), also occurs in acute lymphoblastic leukaemia (ALL).
describe the structure of the Philadelphia chromosome
- The Ph-chromosome is a shortened chromosome 22 produced from a reciprocal translocation of chromosomes 9 and 22
- This translocation causes a fusion of ABL1 and BCR genes
what does BCR-ABL code for
•Encodes a tyrosine Kinase (an enzyme that can transfer phosphate group from ATP to a protein = on/off switch)
what does the tyrosine kinase coded for by BCR-ABL do
- Encodes a tyrosine Kinase (an enzyme that can transfer phosphate group from ATP to a protein = on/off switch)
- Is ‘Constitutively active’ – Does not require activation from, and is is unregulated, by cytokines (i.e does not switch off)
- Leads to uncontrolled, proliferation and cell division
- Also inhibits DNA repair – leading to genetic instability
what can be used for monitoring BCR-ABL transcript levels in real time
- RT - PCR
- Quantifies the precise amount of BCR-ABL positive RNA
- For normalisation the levels of BCR-ABL RNA are compared to expression of the control gene ABL
- Patients are monitored every 3 months
what is the treatment for CML
- Tyrosine kinase inhibitors to inhibit signalling therefore stopping uncontrolled proliferation of the cell
- Imatinib 1st generation trysoine kinase inhibitor and 2nd and 3rd TKI ) dasatinib, nilotinib)
- Some people do not respond to TKI – therefore chemotherapy used
- Chemotherapy for refractor/accelerated phase/Blast crisis
- Allogenic haematopoietic stem cell transplant
What is the prognosis for CML
- Now excellent in era of TKIs – normal life expectancy
- Ongoing trials for cessation of therapy
- Small proportion of patients are resistant to TKIs who need chemotherapy and bone marrow transplant
What is primary polycythaemia vera
- Clonal disorder that results in an increased production of red blood cells
- Seen an increase in red cell volume due to clonal malignancy of a marrow stem cell
what does primary polcythaemia vera look like on a full blood count
– raise in haemoglobin and raise in haematocrit present due to the increased in red blood cell volume
- Usually > RBCs but all 3 cell lines can be increased
what mutation does primary polycythaemia vera result from
- Results from JAK2 mutation – in 95% of cases
What is the median age of primary polycythaemia vera
- Median age is 60
What is the definition of haematocrit
– percentage of blood volume made out of red blood cells – normal is 55% (a rise can also be caused by dehydration)
what can cause a rise in haematocrit
False raise = dehydration
True raise = increase in red blood cell
what are the causes of polycythaemia
- Raised haematocrit
what can cause a true raise in haematocrit ( caused by increase in red blood cell volume)
- Primary - EPO will decrease and this is polycythaemia vera
- Secondary – caused by overproduction of EPO
- Secondary can be hypoxia driven – high altitude, cardiopulmonary disease, defective oxygen transport
- Or secondary can be hypoxia independent – renal cysts, extrarenal tumours, exogenous EPO/drugs
What are the clinical features of primary polycythaemia vera
- May be asymptomatic and detected on FBC or present with vague symptoms due to hyperviscosity = headaches, dizziness, tinnitus, visual disturbance, itching after a hot bath and erythromelagia, burning sensation in fingers and toes are characteristic
- Signs – facial plethora and splenomegaly
How do you diagnose primary polycythaemia vera
Stage 1
- History
- Examination
- Full blood count
- Ferritin
- Renal and liver function
- JAK 2 mutation – definitive test – what happens when you have this mutation this protein becomes continually active so you get uncontrolled proliferation of RBC
Stage 2
- Serum EPO (low)
- Arterial SO2(to look for secondary causes)
- Abdominal US (Splenomegaly, renal tumour)
- Bone marrow biopsy (hyperceullar, trilineage growth (panmyelosis))
- Red cell mass study (nuclear study determines if true or relative erythrocytosis)
What is the prognosis of primary polycythaemia vera
- Median survival 10-16 years
What common causes death in primary polycythaemia vera
- Cardiovascular events
- Thrombosis
- Progression to myelofibrosis – 30%
- Progression to AML – 5%
- Can also geta. Secondary haemorrhage
What is the treatment of primary polycythaemia vera
- Venesection (HCT <0.45 to reduce the risk of thrombosis) – blood is removed – same process as donating blood
- Aspirin - reduces the risk of thrombotic events
- Myelosuppressive drugs – hydroxycarbamide, interferon, busulphan
- Future – JAK inhibitors
What is essential thrombocythemia
- Proliferation of megakaryocytes and thus an increase in the number of platelets
- Defined by a non-reactive thrombocythaemic state that is not accounted for by another MPN
List some statistics for essential thrombocythemia
- Good survival – prevalence of 24/100,000
- More in females then males
- Mediation age of 60 years
How do you diagnose essential thrombocythemia
Diagnosed by ruling out all other causes of raised platelet count
what are the clinical features of essential thrombocythemia
- Many are asymptomatic
Common in essential thrombocythemia
- Thrombosis (arterial and venous)
- Haemorrhage (poor platelet function)
- Erythromelalgia
Other features
- Splenomegaly: early satiety, left upper quadrant fullness/pain
- Fatigue, malaise, weigth loss
What is found in diagnosis of essential thrombocythemia
- JAK2 mutation – 50%, CALR- 30%, MPL- 10%
- Bone marrow biopsy – elevated megakaryocyte’s
What is the prognosis of essential thrombocythemia
- Most enjoy N survival > 10 years, beyond 10 years it is less clear
- Risk of thrombosis, bleeding
- Transformation to MF (10-20%) and AML( <5%)
What is the treatment of essential thrombocythemia
- Aspirin
- High risk patients – age of 60 years, previous thrombosis, high white cell count
- Myelosuppressive drugs – normalise the platelet count – at high risk of CVD
- Hydroxycarbamide
- Anagrelide
What are secondary causes of thrombocytosis
- Infection
- Inflammation
- Iron deficiency
- Haemorrhage
- Hyposplenism
- Malignancy
- Drugs – steroids
What is myelofibrosis
- Clonal stem cell malignancy
- Progressive generalised reactive fibrosis of bone marrow in association with hameatopoesis of the liver and spleen
- Fibrosis is secondary to hyperplasia or abnormal megakaryocytes stimulating fibroblasts
What are the types of myelofirbosis
- Primary
- Secondary
What are the clinical features of myelofirbosis
Particulary
- B symptoms Fatigue, weight loss, night sweats
- Massive splenomegaly – due to extramedullary haemopoiesis
Others
- Raised white cell count
- Progressive cytopenia’s
what do you find in the blood film of myelofibrosis
- Teardrop poikilocytes (abnormal shape of a red blood cell
- Leucoerythroblastic (white and nucleated red blood cells and blasts)
What do you find in the bone marrow of myelofibrosis
- Increased reticulin fibrosis
- Streaming – all the haemopoietic cells is disrupted and replaced by scar tissue
- Hypercellular
how do you diagnose myelofibrosis
- JAK-2 mutation in 50 -60%
- CALR Mutation in 30% (Better prognosis) • MPL mutation in 10%
- Triple negative 10% (worst prognosis)
- Bone marrow Reticulin Fibrosis
- Splenomegaly
- Anaemia
- Leucoerythroblastic blood film + Teardrop poikilocytes
What is the treatment of myelofibrosis
- Stratify risk (age/blast count)
- Supportive Management – transfusion
- Splenectomy/ Splenic irradiatiom
- If high risk and fit patient - ?Allogeneic Tx candidate – only chance of a cure
- JAK Inhibitors – Ruxolitinib – potentially disease modifying. Indicated for B Symptoms and splenomegaly
- Hydroxycarbamide
- Androgens/Danazol
What is the prognosis of myelofibrosis
- Poor overall
- Median survival 1 year if high risk, > 12 years if low risk
- Risk depend of factors – blast count, age, cytogenetics, transfusion dependence
- Progresses to AML
What mutations cause myelofirbosis
- JAK2 mutation in 50% , CALR 30%, MPL 10%
What do investigations show in polycythaemia vera
- RCC raised, HB raised, HCT raised, PCV raised also often raised WBC and platelets
- B12 raised
- Marrow shows hyper cellularity with erythroid hyperplasia
- Cytogenetic as required to differentiate from CML
- Reduced serum erythropoietin
- Raised red cell mass
What can polycythamiea vera transition into
- Transition to myelofibrosis occurs in 30% or acute leukaemia in 5%
What are the symptoms of essential thrombocythaemia
abnormal bleeding such as
- headache
- atypical chest pain
- light headless
- erythromelagia
What cells are present in myelofibrosis
leucoerythroblastic cells characteristic of teardrop red blood cells
What happens in a myeloma
- Due to an abnormal proliferation of a single clone or plasma or lymphoplasmacytic cells leading to secretion of immunoglobulin (Ig) causing the dysfunction of many organ
What is the classification of a myeloma based of off
- Based on Ig produce IgG in 2/3, IgA in 1/3
- 2/3 Urine contain bence jones protein which are free Ig light chains of kappa or lambda type filtered by the kidney
What are the clinical features of a myeloma
CRABBI – Calcium, Renal, anaemia, bleeding, bones, infection)
- Osteolytic bone lesions – cause backache, pathological fractures and vertebral collapse
- Hypercalcaemia – may be symptomatic, lesions are due to increase in osteoclast activation from signalling by myeloma cells
- Anaemia, neutropenia or thrombocytopenia – may result from marrow infiltration by plasma cells leading to symptoms of anaemia, infection and bleeding
- Recurrent bacterial infections – due to immunoparesis and because of neutropniea due to the disease and from chemotherapy
- Renal impairment – due to the light chain deposition – they have an inflammatory effect on the proximal tubule cells
What tests do you do for a myeloma
- FBC – normocytic normochromic anaemia
- Blood film – Rouleaux
- Persistently raised ESR
- Urea and creatine is raised
- Calcium is raised
- Screening tests = serum and/or urine electrophoresis, B2 microglobulin
- Imaging – X rays; lytic punched out lesions, e.g. Pepper-pot skull, vertebral collapse, fractures or osteoporosis
- CT or MRI may be useful to detect lesions not seen on XR
What is the diagnostic criteria used for a myeloma
- Monoclonal protein band in serum or urine electrophoresis
- Increase in plasma cells on marrow biopsy
- Evidence of end organ damage from myeloma – hypercalcaemia, renal insufficiency, anaemia
- Bone lesions – A skeletal survey diagnosis detects bone lesions
What is the treatment for a myeloma
- Analgesia for bone pain – give all patients a bisphosphonate as they reduce fracture rates and bone pain
- Anaemia should be corrected with transfusion and erythropoietin may be been used
- Renal failure – rehydrate and ensure adequate fluid intake of 3L/day to prevent further light chain induced renal impairment
- Infections – treat rapidly with broad spectrum antibiotics until culture results are known
- Regular IV immunoglobulin infusions may be needed if recurrent
- Chemotherapy
What are the complications for a myeloma
- Hypercalcaemia – occurs with active disease e.g. at presentation or relapse
- Spinal cord compression
- Hyper viscosity
- Acute renal injury
