Week 10

• Leukaemias

  Different types of blood cancers
• Acute leukaemias

  Accumulation of precursor/immature cells (blasts)
• Chronic leukaemias

  Accumulation of mature cells
• Types of leukaemia

  • Acute Myeloid Leukaemia (AML)
  • Acute Lymphoblastic Leukaemia (ALL)
  • Chronic Myeloid Leukaemia (CML)
  • Chronic Lymphocytic Leukaemia (CLL)
• Acute leukaemias


  • Originate from various cells
  • Acute lymphoblastic leukaemia originates from B cell precursors
  • Acute lymphoblastic leukaemia (T lineage) arises from T cell precursors
  • Some acute myeloid leukaemias originate from myeloid progenitors
• Leukaemias are the most common childhood cancers
• Leukaemia incidence increases with age despite public perception
• Prognosis is far better for children and young adults compared to older adults, with no improvement in outcome of older adults in 30 years
• Normal haematopoietic system

  1. Haematopoietic stem cell (HSC)

  2. Progenitor cells

  3. Mature blood cells
• Acute leukaemia

  The accumulation of early precursor malignant haemopoietic cells in the bone marrow, leading to bone marrow failure
• Acute leukaemia


  • Induces bone marrow failure (reduced production of blood cells)
  • Spontaneous bleeding/bruising
  • Neutropenic sepsis
  • Anaemia
  • Death
• Acute leukaemia

  • Less commonly AML can present with infiltration by proliferating blasts
• Acute leukaemia

  • Hypermetabolism (weight loss, sweats, gout)
  • Leukostasis (retinae, brain and lungs)
  • Tumour lysis syndrome (hyperkalaemia and hyperphosphataemia resulting in acute renal failure)
• Acute leukaemia

  Accumulation of undifferentiated cells called blasts in bone marrow or blood
• Types of acute leukaemia

  • Acute myeloid leukaemia (AML)(derived from HSCs or myeloid precursors)
  • Acute lymphoblastic leukaemia (ALL)(derived from lymphoid precursors)
• AML vs ALL

  • AML: 1% of all cancers, commoner with increasing age, median age at diagnosis: 68 years, cause arise on a background of myelodysplastic syndrome and/or many years after chemotherapy
  • ALL: Most common cancer diagnosed in children, 25% of cancer diagnosis in < 15 years old, 35-40 cases/ 1 x 10^6 /population in Western world, Peak incidence is in 2- 3 years old = 4 x greater than that in infants and children > 10 years, Slight male preponderance, Higher in hispanics >white children> black, Higher in more socio-economically developed countries
• Flow Cytometry

  Detection and quantification of cell surface and cytoplasmic antigens, Cells are incubated with antibodies conjugated to fluorochromes, Cells pass through the cytometer, are excited by a laser, Individual, labelled cells are detected and counted, Multiple colours can be detected per cell, Resolves cell lineage and maturity
• Flow cytometry


  1. Direct beam stop

  2. Laser light

  3. Forward scatter (high angle) Reflection & refraction. Cell size.

  4. Side scatter (low angle) Diffraction. Cell structure.

  5. Fluorescence at longer wavelengths. Intrinsic (autofluorescence) and extrinsic - fluorochromes.
• Flow cytometry in diagnosis of precursor B-ALL

  • CD19
  • CD34
  • Pre-B ALL blasts
• Genetic tests in leukaemia diagnosis and management

  • Chromosome translocations, deletions, inversions, etc
  • Diagnosis
  • Prognosis
  • Detection of Minimal Residual Disease (MRD)
  • Enable "Risk Adapted Therapy"
• 1. banding chromosome analysis

  1. Chromosomes collected only from diving cells, arrested at the stage of metaphase when they are condensed enough to be analysed at 1000x magnification

  2. Chromosome preparation procedure: Tissue culture in vitro (up to several days), Arresting the cells in mitosis ('spindle poison'), Harvest of cells and spreading the chromosomes on glass slides, Chromosome staining/examination under light microscope for numerical and structural changes; aided by digital imaging programs
• FISH (fluorescence in situ hybridization)

  Does not need metaphase, Fluorophore-labelled probe designed to hybridise w/ target, Chromosome prep attached to substrate eg glass slide & incubated, Visualised using fluor. microscope
• Leukaemia Cytogenetics are strong predictive factors for relapse in AML
• Leukaemia Cytogenetics are also strong predictive factors for relapse in ALL
• Acute Leukaemia

  • Enhanced proliferation: Gain of function mutations of tyrosine kinases eg. FLT3, c-KIT mutations, N- and K-RAS mutations, BCR-ABL, TEL-PDGFbR
  • Differentiation block: Loss of function of transcription factors needed for differentiation eg. AML1-ETO, CBFb-SMMHC, PML-RARa
• Approach to Treatment of Acute Leukaemia

  1. In all, but the elderly or medically unfit, intensive initial treatment with combinations of chemotherapeutic drugs is indicated

  2. The aim is to rapidly clear leukaemic cells from the marrow and to restore normal bone marrow function, ie achieve REMISSION

  3. Post remission therapies comprise of further intensive chemotherapy of allogeneic stem cell transplant

  4. CURE is the goal
• APML

  A medical emergency, APML blasts - hypergranular promyelocytes with prominent auer rods
• APML pathogenesis

  1. t(15;17) → PML/RARα fusion protein

  2. Binds DNA blocking transcription and prevents differentiation of promyelocytes

  3. Promyeloblasts accumulate causing leukaemia and bone marrow failure

  4. All Trans Retinoic Acid (Vitamin A derivative) Binds PML/RARa fusion protein preventing DNA binding

  5. Promyeloblasts differentiate and die from apoptosis

  6. Combination ATRA + Anthracycline often curative in APML

  7. Arsenic trioxide also effective
• Response to treatment is age and disease dependent
• Childhood ALL: >98% remission, > 85% cure
• Adult AML and ALL: 60-75% remission, 25-35% cure
• Adults do much less well than children in ALL outcome
• Tweaking regimens has allowed graduated improvement in survival – particularly in children
• Key achievement of medicine in 20th century -turned universally fatal childhood illness into one that is now curable in 80%
• Chronic Myeloid Leukaemia

  Arises at the level of the haematopoietic stem cell
• Chronic Myeloid Leukaemia

  • Constitutes about 15% of all leukaemia
  • Occurs with an incidence of approximately 1-1.5 in 100,000/year
• Philadelphia Chromosome

  Rearrangement brings together two genes ABL and BCR, producing a unique oncoprotein with tyrosine kinase activity
• Tyrosine kinase activity

  1. Adds phosphate groups to other proteins on the amino acid tyrosine

  2. Switching on and off their enzymatic and other functions
• Chronic phase/Accelerated phase of CML

  • Can be asymptomatic
  • Abdominal swelling/discomfort due to an enlarged spleen
  • Feeling "full"
  • Weight loss
  • Itching
  • Bone pain
• Blast phase of CML

  • Can be like acute leukaemia with symptoms of bone marrow failure, fevers, night sweats