8. Chemotherapeutics Flashcards

1
Q

What are the two definitions of chemotherapeutics?

A
  1. The treatment of cancer using specific chemical agents or drugs that are selectively destructive to malignant cells and tissues. 2. The treatment of disease using chemical agents or drugs that are selectively toxic to the causative agent of the disease, such as a virus, bacterium, or other microorganism.
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2
Q

How are chemotherapeutics selectively toxic?

A

They kill or prevents growth of tumour cells but has minimal toxicity against normal surrounding cells.

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3
Q

What term means “The ratio of the toxic, to the therapeutic dose”

A

Therapeutic Index

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4
Q

What adds to the abilty of drugs to achieve selective toxcitiy?

A

Manipulation of Host by supportive therapy and rescue techniques e.g. anti-emetics.

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5
Q

What are the goals of cancer chemotherapy?

A
  1. Cure2. Prolong survival3. Palliation4. Shrink tumours (debulk) prior to surgery (reducing surgical risk)5. Render tumours radiosensitive
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6
Q

By what mechanism doe chemotherapeutics render tumours more radiosensitive?

A

By arresting cell growth at a point in the cell cycle when they are more vulnerable to radiation

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7
Q

What were the classes of chemotherapeutic agents discussed?

A

Alkylating agentsTaxanes Topoisomerase II inhibitorsPlatinum ComplexesAnthracyclines (antibiotics)AntimetabolitesVinca alkaloidsMiscellaneous AgentsBleomycin¥ Asparaginase¥ Hydroxyurea

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8
Q

Nitrogen mustards, Thiotepa, busulfan, Nitrosoureas, mitomycin Procarbazin and dacarbazine are examples of what class of chemotherapeutics?

A

Alkylating Agents.

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9
Q

Paclitaxel, docetaxel and nab-paclitaxel are examples of what class of chemotherapeutics?

A

¥

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10
Q

Etoposide is an example of which class of chemotherapeutic?

A

Topoisomerase II inhibitors

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11
Q

Cisplatin, Carboplatin and Oxaliplatin are all examples of what class of chemotherapeutics?

A

Platinum Complexes

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12
Q

Doxorubicin, Daunorubicin, Idarubicin, Mitoxantrone are all examples of which class of chemotherapeutic?

A

Anthracyclines (Antibiotics)

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13
Q

Methotrexate, Purine antagonists and Pyrimidine antagonists are all examples of what class of chemotherapeutics?

A

Antimetabolites

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14
Q

Vincristine and Vinblastine are both examples of which class of chemotherapeutics?

A

Vinca alkaloids

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15
Q

Nitrogen mustards belongs to which class of chemotherapeutic?

A

Alkylating Agent

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16
Q

Thiotepa belongs to which class of chemotherapeutic?

A

Alkylating Agent

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17
Q

Busulfan belongs to which class of chemotherapeutic?

A

Alkylating Agent

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18
Q

Nitrosoureas belongs to which class of chemotherapeutic?

A

Alkylating Agent

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19
Q

Mitomycin belongs to which class of chemotherapeutic?

A

Alkylating Agent

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20
Q

Procarbazine belongs to which class of chemotherapeutic?

A

Alkylating Agent

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21
Q

Dacarbazine belongs to which class of chemotherapeutic?

A

Alkylating Agent

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22
Q

Paclitaxel belongs to which class of chemotherapeutic?

A

Taxanes

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23
Q

Docetaxel belongs to which class of chemotherapeutic?

A

Taxanes

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24
Q

Nab-paclitaxel belongs to which class of chemotherapeutic?

A

Taxanes

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25
Etoposide belongs to which class of chemotherapeutic?
Topoisomerase II inhibitors
26
Cisplatin belongs to which class of chemotherapeutic?
Platinum Complexes
27
Carboplatin belongs to which class of chemotherapeutic?
Platinum Complexes
28
Oxaliplatin belongs to which class of chemotherapeutic?
Platinum Complexes
29
Doxorubicin belongs to which class of chemotherapeutic?
Anthracyclines (antibiotics)
30
Daunorubicin belongs to which class of chemotherapeutic?
Anthracyclines (antibiotics)
31
Idarubicin belongs to which class of chemotherapeutic?
Anthracyclines (antibiotics)
32
Mitoxantrone belongs to which class of chemotherapeutic?
Antimetabolites
33
Methotrexate belongs to which class of chemotherapeutic?
Antimetabolites
34
Purine antagonists belongs to which class of chemotherapeutic?
Antimetabolites (Base Analogue)
35
Pyrimidine antagonists belongs to which class of chemotherapeutic?
Antimetabolites (Base Analogue)
36
Vincristine belongs to which class of chemotherapeutic?
Vinca alkaloids
37
Vinblastine belongs to which class of chemotherapeutic?
Vinca alkaloids
38
Bleomycin belongs to which class of chemotherapeutic?
Miscellaneous Agents
39
Asparaginase belongs to which class of chemotherapeutic?
Miscellaneous Agents
40
Hydroxyurea belongs to which class of chemotherapeutic?
Miscellaneous Agents
41
Name the main stages(and actions during them) of the Cell Cycle
¥ G1 phase: cell prepares for DNA synthesis (Longest Phase) ¥ S phase: cell generates complete copy of genetic material¥ G2 phase: cell prepares for mitosis¥ M phase: replicated DNA is condensed and segregated into chromosomes (Mitosis, birth of a daughter cell)¥ G0 phase: resting state
42
In which stage of the cell cycle do most Cell Cycle Phase - Specific chemotheraputics act?
S-Phase, during copying of genetic material.
43
Name the two broad categories of chemotherapeutic agents
1. Cell Cycle Phase Sepcific 2. Cell Cycle Non-Specific
44
On what is the effectiveness of Cell Cycle Phase - Specific chemotherapeutics dependent?
Schedule depenedent
45
On what is the effectiveness of Cell Cycle Phase - Non-Specific chemotherapeutics dependent?
Dose dependent
46
Describe the MOA of Alkylating Agents
¥ Alpha side chains covalently bind on to DNA¥ The two side chains can cause cross-links and inter-strand links¥ This causes reading and replication errors (misreading, ring-opening and cross linking)
47
Describe the MOA of Folic Acid Antagonists (Methotrexate)
¥ Inhibits dihydrofolate reductase, depleting intracellular pools of tetrahydrofolate¥ MTX becomes polyglutamated once inside the cell¥ Also used for non-cancer conditions (lower dose)¥ Very toxic to bone marrow (Therefore side-effects. Its use in anti-rheumatoid applications warrants far lower doses given its toxicity to bone marrow)¥ High-dose MTX is given in combination with folinic acid to minimise toxicity
48
Describe the MOA of the "Purin Antagonists"
¥ 6-thiopurines (6-mercaptopurine; 6 thioguanine)¥ Primarily used to treat childhood leukemia¥ 6-MP activated to TIMP which inhibits several enzymes of de novo purine biosynthesis (s-phase specific)¥ Interacts with allopurinol (Used to treat gout, if one they require a reduced dose of purine antagonists)¥ S-Cycles specific
49
Describe the MOA of the "Pyrimadine Antagonists"
5-fluorouracil (5-FU); capecitabineActivated via complex series of enzymatic rxns to FdUMP (i.e. activated in vitro)Inhibits the synthesis of thymineResults in inhibition of DNA synthesis Ð Ôthymineless deathVery short T1/2Very widely used in solid tumours
50
Describe the MOA of Topoisomerase I Inhibitors
Irinotecan and TopotecanSemi-synthetic derivatives from Camptotheca acuminataTopoisomerase I normally relieves torsional strain in DNAThese drugs prevent re-ligation (i.e. donÕt get effective repair)Inhibition of DNA repair increases sensitivity to radiotherapyUsually second line agents
51
Describe the MOA of Topoisomerase II Inhibitors
Topoisomerase II - EtoposideDerived from Podophyllotoxin Binds to DNA Ðtopoisomerase II complexTesticular and small cell lung cancer.Used as 2nd line after poor response to radiation since they arrest the cell in G2/M Cycle, therefore causes the cell to be more susceptible to radiation
52
Describe the MOA of Platinum Analogues
These drugs enter cells and generate a reactive complex that cross-links guanine units in DNA (i.e. inserts itself into the DNA structure, each cisplatin has two bonding sites therefore cross linking occurs, hence similar to alkylating agents)Similar effects to alkylating agentsCisplatin and carboplatin - ovarian and testicular cancer Oxilaplatin colorectalCisplatin is most toxic (one of the most emetogenic and associated with nephrotoxicity and ototoxicity)
53
Describe the MOA of the Vinca Alkaloids
Bind to tubulinPrevent polymerization of tubulin thus preventing microtubule formation Cell cycle-specific (M phase) ApoptosisSmall differences in chemistry changes toxicity and activity Vincristine active in leukemia and is neurotoxicVinblastine active in lymphomas and testicular cancer and is myelosuppressive
54
Describe the MOA of Anti-Tumour Antibiotics
Doxorubicin; daunorubicin; idarubicin; epirubicin; bleomycin; mitoxantroneIsolated from Streptomyces sppFour known mechanisms of action:1. Topisomerase II inhibition2. High-affinity DNA Intercalation3. Alteration of membrane fluidity and ion transport4. Superoxide free radical mediated damage (responsible for the cardiotoxicity associated with these agents) ¥ Activated by metabolism (hydroxylation) (Activated by hydroxylation, which is responsible for the significant side-effect of cardiac fibrosis)¥ Doxorubicin v widely used in breast, endometrial and ovarian cancer & several childhood cancers.¥ Bleomycin v useful in lymphomas, germ cellcancer and head and neck cancer.
55
Describe the MOA of Taxanes
¥ Paclitaxel isolated from the bark of the Western yew tree in 1971.¥ As demand for paclitaxel grew, semi-synthetic derivative doxetaxel was developed¥ Prevent the growth of cancer cells by affecting microtubules.¥ Overall, they encourage microtubule formation, and stop the microtubule disassembly¥ Results in the cell cycle arrest in mitosis.¥ Eventually, cell death by apoptosis.¥ Arrest cell cycle in G2/M¥ Can produce severe hypersensitivity
56
Describe the MOA of Small Molecule Kinae Inhibitors
¥ First targeted therapy ¥ Do not confuse with antibody drugs¥ Small molecules (chemicals)¥ Imantinib was the prototype (Gleevec)¥ Recognise and bind active site of tyrosine kinases (eg BCR-Abl in Chronic Myelogenous Leukemia)¥ Particularly useful in lymphoma and leukemias¥ Many trials ongoing in solid tumours¥ Gefitinib and erlotinib (EGFR inhibitors) use in non-small cell lung cancer when at least one traditional chemo regime has failed. (simply bind different inhibitors) ¥ Sorafenib, pazopanib and sunitinib are vEGF inhibitors
57
What is an important side-effect of Methotrexate?
Very toxic to bone marrow (Therefore side-effects. Its use in anti-rheumatoid applications warrants far lower doses given its toxicity to bone marrow)
58
What is an important side-effect of the Texanes
Can Produce a severe hypersensivity reaction
59
Which is the most toxic chemtherapeutic studied?
Cisplatin, a platinum analogue.
60
What are the common Toxicities for Chemotherapeutics
¥ Neutropenia, anemia, and thrombocytopenia (Together = myelosuppression/bone marrow supp)¥ Mucositis, diarrhea (GI toxicity)¥ Nausea and vomiting¥ Alopecia (usually reversible)¥ Sterility/Infertility (especially sterility in males)
61
Which tissue/organ systems are commonly affected?
Most chemotherapy drugs are active in cells that are rapidly multiplying, thus they are toxic to normal cells that are actively multiplying¥ Bone marrow¥ GI tract¥ Hair follicles