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pm3b: spring > Cancer Chemotherapy > Flashcards

Cancer Chemotherapy Flashcards

1
Q

Give examples of alkylating agents and how they work

A

Damages components that make DNA in cell cycle (G1)

Cyclophosphamide: acts as a pro drug and metabolised in liver to active agent, oral route has no damage to gut wall

Chlorambucil

Melphalan: given orally to mimic phenylalanine for treatment of multiple myeloma, ovarian and breast cancers

Lomustine
Carmustine
Thiotepa
Mitobronitol

Chlormethine: only given IV (too reactive for oral admin) for treatment of Hodgkin’s Lymphoma via multi drug regime

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2
Q

Give example of cytotoxic antibiotics (intercalating agents)

A

Doxorubicin- treats solid tumours
Mitoantrone
Bleomycin
Mitomycin

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3
Q

Give examples of antimetabolites and how they work

A

Incorporated into new nuclear material or combine irreversibly with vital enzymes to prevent normal cell division

Methotrexate
5-Fluorouracil
Mercaptopurine
Cladribine

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4
Q

Give examples of vinca alkaloids

A

Vinblastine

Vincristine

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5
Q

Give examples of sex hormones and hormone antagonists used

A

Oestrogen, progestogens

Hormone antagonists:
Tamoxifen
Anastrazole

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6
Q

Give a detailed explanation on how alkylating agents work

A

Highly electrophilic that react with nucleophiles to form strong covalent bonds

They react with nucleophilic groups in DNA which cross link and then cannot seperate

Example: Combining two strands of guanine deforms structure and polymerase cannot find DNA to replicate

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7
Q

What are the different nucleophilic groups in DNA

A

N-1: cytosine, thymine, adenine, guanine

N-3: adenine or cytosine

N-7: Guanine (most reactive, reacts with electrophilic substances)

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8
Q

Which cancer types do alkylating groups normally target

A

Blood bourne cancers:
Leukaemia and non hodgkin lymphoma

Solid tumour:
Lung, breast, testicular, ovarian

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9
Q

Which anticancer agent originated from mustard gas

A

Alkylating agents

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10
Q

Explain how intercalating agents work (detailed response)

A
  1. Drugs contain a planar aromatic or heteroaromatic ring which can slip into the double helix of DNA and distort its structure: many van der waals interaction with DNA, charged amino acid group is important to form ionic bond with negatively charged phosphate
  2. Once bound, the drug can inhibit enzymes needed for replication and transcription processes
  3. Intercalation prevents normal action of topoisomerase II enzyme- crucial for effective DNA replication
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11
Q

What form do anthracyclins have to be used

A

Anthracyclins are orally inactive and have to be administered via intravenous injection

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12
Q

What is the second mechanism of intercalating agents

A
  1. Harmful to DNA by involving hydroxyquinone moiety which can chelate iron to form a doxorubicin DNA iron complex
  2. Reactive O2 species then forms a single strand break on DNA
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13
Q

Explain antimetabolites mechanism of action

A
  1. Drugs structurally resemble naturally occurring purines and pyrimidines involved in nucleic acid synthesis
  2. They then disrupt DNA synthesis by inhibiting key enzymes needed (purine and pyrimidine production halted)
  3. Become incorporated into the DNA and RNA to produce incorrect codes and cause strand breaks or premature termination
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14
Q

What are dihydrofolate reductase inhibitors and their mechanism of action

A
  1. Folate antagonists like methotrexate
  2. Inhibits dihydrofolate reductase (DHFR) which is essential in folate synthesis
  3. DHFR is crucial to maintain enzyme co-factor tetrahydrofolate FH4
  4. No tetradihydrofolate FH4: synthesis of DNA building block dTMP is aborted which slows down DNA synthesis and cell division
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15
Q

How do you overcome the metabolic block effects caused by methotrexate

A

FOLINIC ACID:

Acts as an alternative source for nucleic acids- acts as a rescue treatment

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16
Q

What cancer types are methotrexate effective in

A
  1. Treats neoplastic cancers like lymphoblastic leukaemias

2. Widely distributed in body fluids so good for systemic cancers like leukaemia

17
Q

What is the role of thymidylate synthase and how do you inhibit it

A

Role: adds methyl group onto FH4 to continue the cycle

5-Fluorouracil is an effective inhibitor that works as a suicide substrate: activated by enzyme catalysed reaction

18
Q

What can you use 5-Fluouracil for to target which cancer types

A

Treatment of breast, liver, skin cancers and causes neurotoxic and cardiotoxic effects

19
Q

How do inhibitors of DNA polymerases work and give an example

A
  1. Catalyse the synthesis of DNA using the four deoxyribonucleotide building blocks: dATP, dGTP, dCTP, dTTP
  2. Example: Cytarbine: analogue of 2’-doxycytidine that is phosphorylated to corresponding triphosphate which acts as competitive inhibitor: used intravenously
20
Q

How does ara-CTP work as a inhibitor of DNA polymerases

A
  1. Acts as a substrate for DNA polymerase and becomes incorporated into the growing DNA chain
  2. Lead to chain termination or prevents replication of modified DNA
21
Q

Give examples of drugs that inhibit tubulin polymerisation

A

Vincristine, Vinblastine, Vindesine: Vinca alkaloids

22
Q

What is Vincristine used to treat (cancer wise)

A

Acute leukaemia
Hodgkin’s lymphoma
Small cell lung carcinoma

23
Q

What is Vinblastine used to treat (cancer wise)

A

Lymphomas
Testicular
Ovarian cancer

24
Q

What is the mechanism of action for vinca alkaloids

A

Prevents formation of microtubule which is necessary in the formation of a spindle

25
Q

Give examples of drugs that inhibit tubuilin depolymerisation

A

Texanes:
Paclitaxel (taxol): derived from bark of yew trees (treats solid tumours)

Docetaxel: treats breast cancer

26
Q

What is the mechanism of action of taxanes

A
  1. Paclitaxel and Docetaxel bind to the beta subunit of tubulin to halt the G2/M stage of cell division
  2. Leads to apoptosis
27
Q

Why are hormones and hormone antagonists used in cancers

A

Some cancers are hormone dependent so requires them to function: can be administered with opposing effect

28
Q

What glucocorticoids are used in cancer treatment and for which cancer

A

Prednisolone and predisone

Used orally for leukaemia treatment and lymphomas

29
Q

What oestrogen’s are used in cancer treatment and for which cancer

A

Ethinylestradiol, diethylstilbestrol to treat prostate cancer by inhibiting leutinizing hormone production

30
Q

What progestins are used in cancer treatment and for which cancer

A

Medroxyprogesterone acetate and Megestrol acetate

Used to treat advanced endometrial carcinoma

31
Q

What androgens are used in cancer treatment and for which cancer

A

Testosterone Propionate

Metastatic cancer

32
Q

What anti-oestrogens are used in cancer treatment and for which cancer

A

TAMOXIFEN AND RALOXIFENE

Antagonises oestrogen receptors and prevents oestradiol from binding for breast cancer

33
Q

Which monoclonal antibodies will trigger an immune response and attack cancer cells

A

Rituximab: treat non-hodgkin’s lymphoma

Alemtuzumab: treat chronic lymphocytic leukaemia

Antibodies signal immune cells to punch holes in cancer cells

34
Q

Which monoclonal antibodies will block signals related to cell division

A

Prevents daughter cells being made

TRASTUZUMAB (herceptin) for HER2 breast cancer

CETUXIMAB: advanced bowel cancer

35
Q

Which monoclonal antibodies will deliver drugs or radiation to cancer cells

A

Antibody carries radiation or drugs

IBRITUMOMAB: non hodgkin’s lymphoma

pm3b: spring (21 decks)

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