Haematological Malignancies (2)

Question 1

what is the normal WBC count?

Answer 1

~11

Question 2

How does Chronic myeloid leukaemia occur?

Answer 2

c-ABL located on chromosome 9 is translocated to breakpoints on chromosome 22 in clustered relatively small region (BCR)

Question 3

What does BCR-Abl induce?

Answer 3

Stronger tyrosine kinase activity

Question 4

How do leukaemic cells induce cell division and proliferation?

Answer 4

Intregins are expressed on leukaemic cells -> Binds to stromal cells -> Stops normal cell division -> Integrins detach but leukaemic cells are still attached to stromal cells -> cell division and proliferation

Question 5

What is the tyrosine kinase activity in BCR-Abl important for?

Answer 5

To be able to transform cells

Question 6

What drug targets Abl and BCR-Abl?

Answer 6

Imatinib

Question 7

What else does Imatinib target?

Answer 7

Tel-Abl
PDGFR
KIT

Question 8

How does Imatinib work in CML?

Answer 8

It binds to the ATP binding pocket
BCR-Abl require the binding pocket to convert ATP to ADP and therefore phosphorylate the tyrosine kinase motif to activate BCR-Abl

Question 9

How many people who have bone marrow transplants die due to treatment?

Answer 9

~20-30%

Question 10

How long can symptoms of CML take? And why?

Answer 10

5 years due to the removal of the bone marrow

Question 11

What is the survival rate at 10 years using imatinib?

Answer 11

83.3%

Question 12

What factors can you monitor to see if a patient is improving with imatinib?

Answer 12

Blood count (haematological)
Philadelphia chromosome (cytogenetic) 
BCR-Abl1 level (molecular level)

Question 13

What is a complete response?

Answer 13

If you cannot detect any BCR-Abl

Question 14

How do you predict if someone has a complete response and their life expectancy wont change?

Answer 14

Their blood count is restored
The philadelphia chromosome has been removed
BCR-Abl has been removed

Question 15

What is a long term side effect of imatinib?

Answer 15

Fluid accumulation in the lungs (take take 3 years to present) - causes breathlessness

Question 16

What are the side effects of imatinib?

Answer 16

Hemorrhage 
Edema 
Nausea and vomiting 
Low blood count
Fever 
Diarrhea 
Skin rash 
Muscle cramps and bone pain 
Vascular obstruction 
Pleural effusion 
Pulmonary hypertension

Question 17

What are the issue with imatinib?

Answer 17

Toxicity
Sub-optimal response
Disease re-emergence

Question 18

Due to the issues with imatinib, what have been developed?

Answer 18

Second generation drugs

Question 19

Give some examples of second generation drugs

Answer 19

Nilotinib
Dasatinib
Ponatinib

Question 20

How does resistance typically occur to imatinib?

Answer 20

due to mutations in the ATP binding site which imatinib binds to

Question 21

What is the best second generation drug and why?

Answer 21

Ponatinib

T315 mutations in CML - this drug is still able to bind

Question 22

Name a rare subset of AML

Answer 22

Acute promyelocytic leukaemia (APL)

Question 23

How many patients die at presentation of APL?

Answer 23

30%

Question 24

What is one of the main issue with APL?

Answer 24

Commonly get brain bleeds

Question 25

How is APL characterised?

Answer 25

By blood coagulation abnormalities

Question 26

What chromosomes are associated with APL?

Answer 26

Chromosome 15 and 17

Question 27

What gene is on chromosome 15?

Answer 27

PML

Question 28

what gene is on chromosome 17?

Answer 28

RARalpha

Question 29

What chromosome is formed in APL patients?

Answer 29

PML-RARalpha

Question 30

What does chemotherapy do to APL patients?

Answer 30

Increased bleeding and increases risk of early death

Question 31

What is the treatment for APL patients?

Answer 31

Vitamin A analogue, retinoic acid

Question 32

What is RARalpha?

Answer 32

A nucleur hormone receptor

Question 33

What does RARalpha form a heterodimer with?

Answer 33

Retinoid X Receptor (RXR)

Question 34

What does RARalpha/RXR bind?

Answer 34

Retinoic acid response elements (RAREs) in the promoter region of genes, including those regulating myeloid differentiation

Question 35

What silences genes?

Answer 35

``` DNA methyltransferases Histone deacetylases (HDAC) ```

Question 36

What increases gene activity?

Answer 36

Histone acetyltransferases (HAT)

Question 37

What normally happens in the absence of retinoic acid?

Answer 37

RARalpha-RXR heterodimer recruits corepressors, including HDACs -> silence target gene expression

Question 38

What normally happens in the presence of retinoic acid?

Answer 38

RARalpha binds to retinoic acid -> conformational change in the RARalpha/RXR heterodimer -> release of the nucleur co-repressors and recruit coactivators -> increase gene expression

Question 39

What happens in PML-RARalpha?

Answer 39

It cannot response to physiological conditions of retinoic acid -> represses gene transcription -> causes t to stay as a primitive cell

Question 40

What are the effects of PML-RARalpha?

Answer 40

Alters the epigenetic landscape through histone deacetylation Affects transcription of genes controlled by other nuclear factors Stimulates the transcription of hypoxia-induced factors (pro-angiogenesis) suppresses PML-nuclear body and p53 responses

Question 41

What is the effect of pharmacological all trans retinoic acid (ATRA) on APL?

Answer 41

Overcomes the suppressive effects of protein PML-RARalpha Recruits histone demethylase May involve proteolytic degradation of PML-RARalpha Differentiation of leukaemic cells into mature granulocytes -> growth of normal bone marrow

Question 42

What is ATRA effective with?

Answer 42

chemotherapy

Question 43

What is the clinical outcome of APL?

Answer 43

90% remission and a high rate of cure with combined ATRA and reduced intensity chemotherapy

Question 44

What chemotherapy is used with ATRA?

Answer 44

Arsenic trioxide

Question 45

How does arsenic trioxide work?

Answer 45

Increases ROS -> Disulphide links in PML or PML-RARalpha and binding to arsenic -> forms nuclear matrix associated nuclear bodies by disulphide-linked multimers -> Sumoylation and degradation of PML-RARalpha Can induce molecular remission

Question 46

What is the survival rate of ATRA and Arsenic trioxide?

Answer 46

97% at 5 years

Question 47

What are Bispecific T cell engager antibodies?

Answer 47

They have dual specificity for tumour antigen and CD3 | Functionally replace the MHCI/peptide/TCR complex