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HDT 3.2 > Cancers > Flashcards

Cancers Flashcards

1
Q

what cells consists within tumour microenvironment (TME)?

A

cancer stem cells
cancer cell
endothelial cells
pericyte
cancer-associated fibroblasts
invasive cancer cells
immune inflammatory cells (ICs)

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2
Q

how do the different cells in the TME communicate?

A

secreted growth factors
enzymes
and cytokines

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3
Q

where are immune cells derived from?

A

haemolytic stem cells (HSC)
from the bone marrow

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4
Q

what do Hematopoietic stem cells (HSC) form?

A
  1. myeloid progenitor cells - passive immune cells
  2. lymphoid progenitor cells - adaptive immune cells
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5
Q

what are myeloid progenitor cells?

A

macrophages

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6
Q

what are lymphoid progenitor cells?

A

CD8 T cells
CD4 T cells
memory cells
plasma cells

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7
Q

What is immune tolerance?

A

Refers to the immune system’s state of unresponsiveness to substances or tissues that would otherwise trigger an immune response.

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8
Q

What is Central tolerance?

A
  • occurs for premature immune cells, known as thymocytes
  • strongly self reactive immature lymphocytes deleted
  • increase affinity binding = cell death
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9
Q

What is Peripheral tolerance?

A
  • apoptosis of lymphocytes that recognise self antigens in the periphery
  • suppression of responses by regulatory T cells (Tregs)
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10
Q

what is immune surveillance theory?

A

constantly monitoring the body for the appearance of tumour cells, and that the majority of these abnormal cells are destroyed by the immune system before giving rise to clinically manifest tumours.

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11
Q

How does the immune system identifies tumour cells?

A

using neoantigens

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12
Q

how are neoantigens formed?

A

mutations in the cancer genome = tumour antigens

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13
Q

how do T cells get activated?

A

T cell receptor (TCR) on naive T cell binds to the antigen presented on the MHC (1 or 2) on the antigen presenting cells (APCs) = primary signalling

a second costimulatory signal is required for full activation of T cells

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14
Q

what is MHC 1/2?

A

human leukocyte antigen

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15
Q

whats an example of APC?

A

antigen presenting cells
dendrite

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16
Q

how is a second co-stimulation signal mediated?

A

tightly controlled interplay of stimulatory/inhibitory receptor and ligand pairs also known as IMMUNE CHECKPOINTS

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17
Q

what is an example of a second co-stimulation signal?

A

CD28 signal

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18
Q

what are immune checkpoints?

A

receptors/ligand pairs that activate full T cell activation thru a second co-stimulatory signal

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19
Q

what is CTLA4?

A
  • member of CD28 receptor family on T cells
  • out competes with CD28 ligands for B7-1 on the APC due having a higher affinity with CTLA4
  • inhibits immune response at the priming phase of T cell activation
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20
Q

describe CTLA4 blockade for cancer therapy

A

anti-CTLA4 - ipilimumab

prevents its interaction with B7 ligands.

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21
Q

what are the side effects of ipilimumab?

A

skin lesions (rash/ vitiligo)
colitis
hepatitis/ hypophysitis/ thyroiditis

dose-dependent irAE’s

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22
Q

explain the mechanism of anti-CTLA4?

A
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23
Q

what is PD1?

A

IMMUNE CHECKPOINT for activated t cells
inhibitory function mediated by the tyrosine phosphatase SHP-2, which dephosphorylates signalling molecules downstream the TCR

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24
Q

What does PD1 bind to ?

A

PD-L1
PD-L2

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25
Q

what does inflammation induced PD-L1 expression on B cells cause?

A

PD1 T cell exhaustion = inhibiting CD8 response

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26
Q

name some IMMUNE CHECKPOINTS?

A

activated T cell - PD1
naive T cells - CTLA4

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27
Q

how is PD-L1 expressed?

A
  1. TCR binds to the antigen in the MHC
  2. binding induces IFN-y expression
  3. IFN-y recognition via cancer cell receptors
  4. IFN-y receptors signals to JAK1/2 receptors
  5. JAK 1/2 receptors induces PD-L1
  6. blocks activated T cells
28
Q

what are examples of anti-PDL1?

A

pembrolizumab - melanoma
nivolumab

29
Q

what is pembrolizumab?

A

anti-PDL1 antibody for mismatch repair deficient cancer (dMMR) for solid tumours

30
Q

explain anti-PDL1 MOA ?

A
31
Q

whats the difference between anti-CTLA4 and anti-PDL1?

A
32
Q

what are mechanisms of resistance to immune checkpoint inhibitors?

A
  1. primary - pt does not respond
  2. acquired
    • intrinsic - alter processed related to (immune recognition/cell signaling/gene expression/DNA damage response)
    • extrinsic - Resistance occurs external to tumor cells throughout the T-cell activation process
33
Q

what is immunoediting?

A

A dynamic process involving the immune system’s recognition, shaping, and elimination of cancer cells, comprising three phases: elimination, equilibrium, and escape.

34
Q

high tumour intra-heterogeneity can cause what?

A
  • Treatment resistants
  • Metastisis
  • Tumour recurrance
35
Q

what can cause resistance to IMMUNE CHECKPOINT BLOCKADE?

A
  1. immune suppressive cells w/ inhibitory cytokines = undermine anti-tumour response
    - Tregs/ myeloid derived suppressive cells (MDSCs) tumour infiltration
  2. M2 macrophages = promote tumour progression
  3. VEGF high levels in PD1 non-responding patients
  4. impaired priming of naive T cells
  5. tumour mutations = loss of HLA expression
  6. patients who respond poorly too aPD1 therapy = less tumour associated memory T cells
  7. wnt/b-catenin signalling
36
Q

what are immune suppressive cells w/ inhibitory cytokines ?

A
  • Tregs
  • myeloid derived suppressive cells (MDSCs) tumour infiltration
37
Q

what cell signalling pathways influence immune response?

A
  1. hyper-activation of MAPK signalling = less TILs recruitment thru VEGF expression
  2. PTEN deletion = decrease cytotoxic T cell activity = resistance to aPD1
  3. WNT/B-catenin ICB resistance
38
Q

what is cancer screening?

A

testing healthy people for signs of the disease at an early age to prevent cancer developing and better survival chances

39
Q

what are the two types of cancer screening?

A
  1. opportunistic - symptoms displayed and screened by doctors
  2. population based - cohort of people to screen (e.g. women aged >60yrs old)
40
Q

what does early detection of cancer allow?

A

allow better treatment plans with a high survival rate

41
Q

what makes a cancer suitable for screening?

A
  • effective tests (high specificity and sensitivity)
  • test should be acceptable to the population (ppls morals n ethics)
  • healthcare system can cope with the downstream impact of positive results
  • must increase survival
42
Q

why must cancer screening be highly specific and sensitive?

A

highly specific - low chance of a false positive

highly sensitive - low chance of getting a false negative

THEREFORE IMPORTANT

43
Q

what do screening tests include?

A

Physical examination
e.g. checking skin for moles
▪Laboratory tests
e.g. measuring levels of PSA, examining cervical tissue samples
▪Imaging procedures
e.g. Breast mammography
▪Genetic Tests
e.g. BRCA testing

44
Q

who should we be screening?

A

Usually screening focuses on people at increased risk of a disease due to:
▪ Family history / genetic mutations
e.g BRCA testing
▪ Exposure to cancer-causing agents
e.g. lung cancer for smokers
▪ Age
e.g. elderly

45
Q

why do we have to be careful to screen elderly?

A

risk-benefit ratio with treatments
may not be clinically sustainable

46
Q

what are the pros and cons of screening?

A

pros:
-better outcome
-less radical therapy needed
-reassurance for pts with negative results
-psychological benefit
-less complex therapies=cheaper

cons:
-cost of screening
-risk of false positives
-longer morbidity if prognosis is unaltered

47
Q

describe uk’s breast cancer screening programs

A

offered to 50-70 yr old; women.
every 3 years
high risk pts (family history/prior cancer) will be offered earlier screening

uses X-ray tests - mammogram

48
Q

what is the chance of women developing breast cancer ?

A

clinically 1 in 7 women

49
Q

what was the main risk of breast cancer screening?

A

increased risk of over-diagnosis - screening picks up cancers that would have never manifested clinically, thus skewing the survival rates

50
Q

what does over-diagnosis mean?

A

screening picks up cancers that would have never manifested clinically, thus skewing the survival rates

51
Q

describe uk’s cervical cancer screening programs

A

25-64 yrs old
every 3 yrs til 49yrs old, then every 5 years

Small sample of cells taken from the cervix. Sample is checked for high risk human papillomavirus (HPV) that can cause changes to the cells of the cervix.

If these types of HPV are not found, no further tests are undertaken.

If these types of HPV are found, the sample is then checked (using liquid based cytology) for any changes in the cells of the cervix. If changes detected, patient invited back for a colposcopy

52
Q

how has cervical cancer screening helped?

A

mortality rates decreased by 70%
incidence to reduce further due to HPV vaccines

53
Q

what is a main cause of cervical cancer?

A

HPV virus

54
Q

what can we do to prevent cervical cancer?

A

vaccine against HPV

55
Q

why are cervical cancer screening programs not <25 or >65 yrs old?

A

If you’re <25
▪ cervical cancer is very rare in people under 25
▪ it might lead to having treatment you do not need – abnormal cell changes often go back to normal in younger women

If you’re 65 or older
▪ You’ll usually stop being invited for screening once you turn 65. This is because it’s very unlikely that you’ll get cervical cancer.
▪ Only be invited again if 1 of your last 3 tests was abnormal.

56
Q

describe uk’s bowel cancer screening programs

A

bowel scope no longer offered

offered to 60-74 yrs old, at specific antibody home test kit every 2 years

hoping to lower bowel screening age to 50 in the future

57
Q

what kits are used for bowel cancer screening?

A

faecal occult blood test (gFOBT) less accurate = less used

faecal immunochemical test (FIT) - more accurate = easier to use

58
Q

what do the specific antibodies in the human blood detect?

A

detect human blood in the stool

59
Q

what are the statistics of bowel screening?

A

2 out 100 will be positive and offered a colonoscopy

60
Q

describe uk’s prostate cancer screening programs

A

not offered but >50yrs old request tests to be done

not ideal as incidence is increasing due to an ageing population

61
Q

describe uk’s lung cancer screening programs

A

lung health checks trialled - pts determined to be high risk of lung cancer will be invited for CT screening

62
Q

what screening programs do we have ?

A

-breast
-cervical
-prostate
-bowel
(-lung)

63
Q

what screening programs may we have in the future?

A

(-lung)
-skin
-ovary
-thyriod
-endrometrium

OTC screening kits
genetic screening for all common cancer - breast/prostate/bowel/ovary

64
Q

how can pharmacists aid cancer screening?

A
  • encourage people to attend/undertake screening
  • provide information/reassurance about the screening process
65
Q

what are the barriers for people to not attend to cervical screening?

A

frequent non attenders:
- ethnic minorities
- women over 50 and 25-29
- lesbian/bisexual women
- lower socio-economic groups

do not attend due to:
- embarrassed to have a smear test
- worried of the result
- concerned about the procedure
- access to screening and appointment times
- don’t think they are at risk
- unaware of screening

HDT 3.2 (17 decks)

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