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TIN > WK 9- CANCER CHEMOTHERAPY > Flashcards

WK 9- CANCER CHEMOTHERAPY Flashcards

1
Q

What are the 4 classes of drugs that act on the structure of DNA

A
  1. Topoisomerase inhibitors
  2. Intercalating Agents
  3. Alkylating Agents
  4. Antimetabolites
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2
Q

What is the action of antimetabolites

A

Interfere with the incorporation of nucleic acid bases (C, T, A, G) into the DNA during DNA synthesis: basically like inducing mutations

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3
Q

What are the 2 outcomes of antimetabolites

A
  1. Chemical modification of a nucleic acid to prevent accurate replication
  2. Inhibit reduction of folic acid
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4
Q

What 2 drugs cause chemical modification of a nucleic acid to prevent accurate replication

A

5-fluorouracil (synthetically modified form of uracil- also inhibits thymidine synthetase), gemcitabine (also inhibits ribonucleotide reductase)

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5
Q

What is the action of methotrexate (antimetabolite)

A

inhibit folic acid reduction- folate is essential for the transfer of methyl groups in DNA synthesis) from its inactive dihydrofolate → active tetrahydrofolate (therefore no active tetrahydrofolate is produced)

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6
Q

What is the action of alkylating agents

A

Form methyl cross-bridges between base pairs (A==T; C==G) to prevent the two DNA strands coming apart during mitosis and stop formation of daughter DNA fragments-> basically tie the two DNA strands together and stop cell division

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7
Q

What class does cyclophosphamide belong to

A

Alkylating agents

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8
Q

Why does renal/bladder function need to be monitored in pt taking cyclophosphamide

A

break down of cyclophosphaminde→ forms inactive metabolites and toxic metabolites→ these increase in conc in bladder/kidney and cause side effects

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9
Q

What are intercalating agents

A

Similar to alkylating agents-> Intercalating agents wedge between bases along the DNA (A--T and C--G). The intercalated drug molecules affect the structure of the DNA, preventing polymerase and other DNA binding proteins from functioning properly-> Stops two strands coming apart and stops replication

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10
Q

What specific intercalating agent binds to Guanine to cross link within/across strands

A

Platinum compounds-> cisplatin

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11
Q

True or false, intercalating agents are cytotoxic antibiotics

A

True- anthracyclin is a cytotoxic antibiotic

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12
Q

What is the function of bleomycin-> what class does it belong to

A

Intercalating agents- Partially intercalates to produce direct DNA demage through forming a complex with iron => reactive toxic product

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13
Q

What is the function of topoisomerase

A

Topoisomerase is an enzyme → control tertiary coiling of DNA → topoisomerase enzyme binds to double stranded DNA and cut the phosphate backbone of the DNA strands→ allows the DNA to be untangled or unwound and then the DNA is resealed→ inhibiting this means that mutation continues

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14
Q

What is the function of topoisomerase inhibitors

A

Topoisomerase inhibitors prevent topoisomerase enzymes from being able to fix mutated DNA strands-> allowing damaged cells to continue to proliferate

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15
Q

What are the 2 groups of topoisomerase inhibitors

A

-Topoisomerase I
→ Camptothecin group: Topotecan and irinotecan
-Topoisomerase II
→Podophyllotoxins: Etoposide and teniposide

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16
Q

What 2 classes of drugs act on mitosis

A

Spindle poisons: Vinca alkaloids: vincristine and vinblastine
Taxane group: paclitaxel and docataxel

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17
Q

What are the actions of taxane groups

A

Cause tubulin polymerisation to result in abnormal spindles and cell death

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18
Q

How do signal transduction inhibitors work

A

Inhibition of the tyrosine kinase pathway results in decreased cell growth/proliferation

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19
Q

What drugs are examples of signal transduction inhibitors

A

Imatinib, gefitinibe, sorafenib and sunitinib→ when it ends with ‘ib’ – it is an enzyme inhibitor

20
Q

What is the action of proteosome inhibitors

A

Proteosomes are large protein complexes to regulate and metabolise/remove proteins into small peptide fragments
-If inhibited, the ordered degradation of proteins controlling cell cycle is disrupted → causing apoptosis

21
Q

What is an example of a proteosome inhibitor

A

Bortezomib used in recurrent multiple myeloma

22
Q

How does targeting spindle formation work to treat cancer

A

Mitosis requires spindle formation in the sorting and moving chromosomes following replication at the end of mitosis-> without spindles there cannot be proper cell division

23
Q

What 4 classes of drugs work to target angiogenesis

A
  1. Monoclonal antibody to target VEGF receptors
  2. VEGF receptor tyrosine kinase inhibitor (inhibits receptor
  3. Vascular disrupting agents
  4. Thalidomide and lenalidomide
24
Q

What are 4 types of cancer that are highly sensitive to chemotherapy

A

Leukemia, lymphoma, myeloma, germ cell tumours

25
Q

What are 4 types of cancers that have medium sensitivity to chemotherapy

A

Breast, colorectal, bladder, ovary

26
Q

What 5 cancers have low sensitivity to chemotherapy

A

Prostate, kidney, brain, sarcomas, melanomas

27
Q

What are the 6 common limiting toxicities from chemotherapy

A

Bone marrow suppression, bowel toxicity, renal damage, neurological damage, cardiac, and bladder toxicities

28
Q

What are the 4 mechanisms by which cancer cells can become resistant to drugs

A
  1. Altered biochemical pathways:
    →Modified folate use to avoid dihydrofolate reductase block by methotrexate
  2. Altered cell transport mechanisms;
    → To prevent drug concentration in cancer cells by reduced uptake or enhanced flux
  3. Altered drug metabolism:
    → Increasing clearance, Reducing drug activation
  4. Impaired apoptotic mechanisms
29
Q

How do cancer cells develop resistance to drugs

A

due to cancer cells being heavily dividing→ there are mutations that constantly occur→ some can benefit the survival of the cells (eg. Getting rid of cytoxic drug from the cell-> allowing cell to survive and continue to replicate)

30
Q

What gene encodes for the transporter that allows for multi-drug resistance

A

MDR1 gene encodes for a glycoprotein important in cell transport-> aids in extruding foreign molecules from the cell and ridding cytotoxic drugs from within the cells

31
Q

What 2 drugs can be used to overcome multi-drug resistance

A

Verapamil and cyclosporine→To inhibit efflux of cytotoxic drugs (keep them in cell to concentrate their action)

32
Q

Which types of cancers are;

  1. oestrogen sensitive
  2. androgen sensitive
  3. oestrogen and progesterone sensitive
A
  1. Breast cancer
  2. Prostate cancer
  3. Endometrial cancer
33
Q

How is hormone therapy used within cancer treatments

A

If a tumour is hormone sensitive, then it utilises the hormone to grow-> hormone therapy will either work through blocking the hormone receptors on the tumour or through administering hormones to cause down-regulation of receptors and disruption of the hormonal axis

34
Q

What are the 3 treatment methods by which hormonal therapy treats breast cancer and what drug is used for each method

A
  1. Direct binding to estrogen receptor (ER) and blockage of ER activity→ tamoxifene
  2. Indirectly by blocking production and peripheral activation of oestrone and oestriol to oestradiol by inhibiting aromatase (oestradiol is most common form of oestrogen)→ anastrozole and letrozole
  3. Down-regulation of ER→ decreased sensitivity to oestrogens (2nd or 3rd line treatment)→Medroxyprogesterone (progesterone)
35
Q

What are the side effects of the hormonal therapies used in breast cancer

A

Artificially create menopause-like situation by blocking or decreasing oestrogen

  • Anti-oestrogens: hot flushes, fluid retention, vaginal dryness, uterine bleeding, DVT
  • Aromatase inhibitors: hot flushes, nausea rashes, joint stiffness, vaginal dryness, high cholesterol, osteoporosis
  • Progesterone: Nausea, fluid retention, weight gain
36
Q

What are the 2 methods by which prostate cancer is treated

A
  1. Direct androgen receptor antagonists

2. Indirectly through disrupting the HPG (hypothalmic-pituitary-gonadal axis)

37
Q

How is the HPG axis targeted

A

target LHRH (central regulator) at level of pituitary by using an agonist→ high doses of peptide agonist causes down regulation of receptors (less responsive)

38
Q

What are biological therapies - what are the two types

A

Chemicals/modified chemicals that are produced by the body in response to injury/infection and include MAB and Alpha-interferon

39
Q

How does alpha interferon aid in killing cancer cells - what 2 cancers is it most commonly used for

A

Aid in enhancing the body’s natural defence to remove malignant cells
-Hairy cell leukemia, renal cancer, melanoma

40
Q

What are monoclonal antibodies

A

Antibodies that act to carry toxic agents to a cell defined by specific surface antigens against which the antibody is targeted→ are specific for antigens on cancer cells

41
Q

What is the action by which MAB act to kill cancer cells

A

-Bind to antigen target and induce immune response to eliminate the cells OR they can be used to bind toxic agents and deliver it directly to cancerous cells

42
Q

What is the method by which trastuzumab works and what does it treat

A

(Herceptin)

-Will bind antigens found on breast cancer cells and ilicit and immune response that will cause killing of the cells

43
Q

What are the 5 types of monoclonal antibody drugs-how do they work

A
  1. Rituximab: CD20 antigen on B-cell lymphomas
  2. Ibritumomab: Anti-CD20 antibody tagged with a radioisotope yttrium-90 for follicular lymphoma→ radioisotope is carried directly to cell
  3. Trastuzumab: Herceptin:
  4. Alentuzumab: Anti-CD52 antibody in chronic lymphocytic leukaemia
  5. Bevacizumab: VEGF antibody (tumour vasculature) in colorectal cancer
44
Q

How do tyrosine kinase inhibitors work

-what suffix do the drugs have

A

Blocking receptors for tyrosine kinase pathways that are abnormally activated in cancers
-‘ib’

45
Q

what is an MTOR inhibitor

A

When mTOR is mutated (ie. hyperactivation of mTOR1) it will cause molecules downstream of mTOR to be activated and cause proliferation and growth
-inhibiting mTOR enhances antineoplastic therapies through decreasing angiogenesis and tumour cell proliferation and growth

46
Q

What are the 3 mechanisms of antineoplastic antibodies

A
  1. Bind to cyclin dependent antigens on malignant lymphocytes and cause cell lysis
  2. Bind to HER2/EGF/VEGFR and inhibit proliferative response–> ie. Trastuzumab (for HER2), Cetuximab (EGFR) and Bevacizumab (VEGFR)
  3. Checkpoint (immune) inhibitors
47
Q

How do checkpoint/immune inhibitors work

A

Bind to CTLA4 (cytotoxic lymphocyte associated antigen 4) and block the interaction between CTLA4 and B7-> when CTLA4 binds to B7 it stops co-stimulation and renders T Cells innactive-> by blocking this connection, T cells are able to be activated and increase the immune response that causes cell death

TIN (14 decks)

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