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Questions and Answers
What is the primary mechanism of action for folate antagonists in cancer treatment?
What is the primary mechanism of action for folate antagonists in cancer treatment?
Which nucleotide analog is known for having a greater affinity for dihydrofolate reductase compared to folate?
Which nucleotide analog is known for having a greater affinity for dihydrofolate reductase compared to folate?
What effect do purine and pyrimidine antagonists have on DNA?
What effect do purine and pyrimidine antagonists have on DNA?
What is one potential side effect associated with anthracycline antibiotics?
What is one potential side effect associated with anthracycline antibiotics?
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During which phase of the cell cycle do most anticancer effects of anthracyclines occur?
During which phase of the cell cycle do most anticancer effects of anthracyclines occur?
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Which two main groups are classified as antibiotic anti-tumor drugs?
Which two main groups are classified as antibiotic anti-tumor drugs?
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What is a common treatment complication associated with the use of methotrexate?
What is a common treatment complication associated with the use of methotrexate?
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What is the effect of folate antagonists on the synthesis of purines and pyrimidines?
What is the effect of folate antagonists on the synthesis of purines and pyrimidines?
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What is the primary function of VEGF in the context of tumors?
What is the primary function of VEGF in the context of tumors?
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Which class of drug is used to block the HER2 receptor in certain tumors?
Which class of drug is used to block the HER2 receptor in certain tumors?
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What is a common side effect associated with antineoplastic antibodies?
What is a common side effect associated with antineoplastic antibodies?
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What is a noted concern regarding the use of thalidomide for treating blood cancers?
What is a noted concern regarding the use of thalidomide for treating blood cancers?
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What role do analogues of GnRH play in cancer treatment?
What role do analogues of GnRH play in cancer treatment?
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What is the primary function of alkylating agents in cancer chemotherapy?
What is the primary function of alkylating agents in cancer chemotherapy?
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Which group of drugs is known for impairing the assembly of nucleic acids in cancer chemotherapy?
Which group of drugs is known for impairing the assembly of nucleic acids in cancer chemotherapy?
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In terms of their mechanism of action, alkylating agents are classified as cell cycle-specific or what?
In terms of their mechanism of action, alkylating agents are classified as cell cycle-specific or what?
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Which of the following is an example of a nitrogen mustard used in chemotherapy?
Which of the following is an example of a nitrogen mustard used in chemotherapy?
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What is the role of folate antagonists in cancer treatment?
What is the role of folate antagonists in cancer treatment?
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Which of the following is considered a characteristic of cytotoxic agents?
Which of the following is considered a characteristic of cytotoxic agents?
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Which type of chemotherapy includes drugs that comprise alkyl groups and react chemically with DNA?
Which type of chemotherapy includes drugs that comprise alkyl groups and react chemically with DNA?
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What distinguishes cell cycle specific agents from cell cycle non-specific ones?
What distinguishes cell cycle specific agents from cell cycle non-specific ones?
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What is a significant characteristic of the mitotic inhibitors?
What is a significant characteristic of the mitotic inhibitors?
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Which of the following is true regarding vinca alkaloids?
Which of the following is true regarding vinca alkaloids?
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What is a common use for podophyllins?
What is a common use for podophyllins?
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What defines the action of taxanes in cancer treatment?
What defines the action of taxanes in cancer treatment?
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How do bleomycin and mitomycin exert their anti-tumor effects?
How do bleomycin and mitomycin exert their anti-tumor effects?
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Which of the following phases do mitotic inhibitors specifically target?
Which of the following phases do mitotic inhibitors specifically target?
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What is a critical precaution when administering vinca alkaloids?
What is a critical precaution when administering vinca alkaloids?
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What effect do mitotic inhibitors have on mitosis?
What effect do mitotic inhibitors have on mitosis?
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Study Notes
History of Cancer Chemotherapy
- 1940s: Nitrogen mustards (chemical warfare agents) were discovered, Goodman & Gilman were pioneers
- 1948: Folic acid antagonists (antimetabolites) were introduced
- 1950s: 6-MP (6-mercaptopurine) and Vinca alkaloids were discovered
- 1965: Combination therapy was introduced
Types of Cancer Chemotherapies
- Radiopharmaceuticals: Also known as "nuclear medicine" or "radiation oncology"
-
Anti-neoplastic agents: These are drugs that act against cancer cells
-
Cytotoxic agents:
- Alkylating agents
- Antimetabolites
- Antitumour antibiotic agents
- Mitotic inhibitors
- Hormonal chemotherapy / Miscellaneous
-
Cytotoxic agents:
Cytotoxic agents
- May have different sites of action on cell division cycle
- ALL inhibit cell replication (anti-proliferative)
- Classified as cell cycle specific OR cell cycle non-specific
- Classification is important for drug choice
Alkylating agents
- Contain alkyl groups (methyl –CH3, ethyl –CH2CH3)
- React with DNA to form strong bonds
- Hold DNA strands together (like a zipper stuck)
- Prevent DNA from unravelling for DNA replication or RNA transcription
- Slow or stop the cell cycle - Mainly at the S phase
Antimetabolites
- Analogues of folic acid OR purine/pyrimidine bases
- Inhibit enzymes involved in pathways of macromolecular synthesis
- Act as false "building blocks", causing impaired polymers of nucleic acids to be assembled
- 3 main groups:
- Folate antagonists (e.g., methotrexate (pro-drug))
- Purine antagonists (e.g., mercaptopurine)
- Pyrimidine antagonists (e.g., fluorouracil)
Antimetabolites: Folate antagonists
- Folate (vitamin B9) is essential for production of DNA and RNA
- Children with leukemia had worse outcomes when taking folic acid
- Folate antagonists mainly act by inhibiting the enzyme dihydrofolate reductase
Antimetabolites: Purine & Pyrimidine antagonists
- Can be incorporated into DNA strands replacing the correct base
- Form permanently modified DNA
- Cause improper base pairing -> improper transcription to RNA
- May also act as inhibitors on enzymes of DNA synthesis
- Phase specific - Act particularly at the S phase of the cell cycle
Antibiotic anti-tumour drugs
- 2 main groups:
- Anthracyclines
- Bleomycins
- Called antibiotics because compounds are isolated from one living organism (fungi) and act against another living organism (neoplastic cell)
Antibiotic anti-tumour drugs: Anthracyclines
- 1950s - Attempts to isolate anti-cancer compounds from microbes in soil (e.g., daunorubicin, doxorubicin, idarubicin)
- Multiple modes of action (MOA), not fully understood
- Bind directly to DNA, inhibiting DNA and RNA synthesis
- Inhibit topoisomerase II
- Intercalate with DNA to impair DNA transcription
- Cell-cycle specific - S phase
- Cardiac toxicity, lifetime maximum dose
Antibiotic anti-tumour drugs: Bleomycins
- e.g., bleomycin, mitomycin (from Streptomyces species)
- Block incorporation of thymidine into DNA, also degrade DNA that is already formed
- Cell-cycle non-specific - G2, M, G0
Mitotic inhibitors
- Natural products - from plants
- 3 groups:
- Vinca alkaloids
- Podophyllotoxins
- Taxanes
- Main action at the metaphase stage of mitotic division
Mitotic inhibitors: Vinca alkaloids
- From Vinca (Europe, Africa, Asia) "periwinkle"
- e.g., vincristine, vinorelbine (oral), vinflunine, vinblastine
- Relatively non-toxic compared to other cytotoxic agents
- Exceptionally neurotoxic - Special precautions to not give intrathecally
Mitotic inhibitors: Podophyllins
- Originally isolated from rhizomes of May Apple
- e.g., etoposide, teniposide
- Kill cells in the S and G2 phase in addition to the M phase
- Used in leukaemias and lymphomas
Mitotic inhibitors: Taxanes
- From Taxus (yews)
- e.g., paclitaxel, docetaxel
- Also stimulate the immune response
- Used to treat breast, lung, and ovarian cancer
Hormonal treatment
- Treatment of neoplasia that are sensitive to hormonal growth controls
- e.g., for thyroid, breast, and prostate cancers
- Includes: corticosteroids, androgens/anti-androgens, oestrogens/anti-oestrogens, progestogens, analogues of gonadotrophin releasing hormone (GnRH)
Miscellaneous Treatments
- Antineoplastic antibodies
- Bind to a specific antigen or factor needed by a cancer cell to proliferate
- VEGF (Vascular Endothelial Growth Factor)
- Needed to create new blood vessels for tumours
- Blocked by bevacizumab (Avastin)
- EGFR (Epidermal growth factor receptor)
- Needed for new ‘endothelial cells’
- SCC, head and neck, colorectal
- Cetuximab (Erbitux)
- HER2 (human epidermal growth factor receptor 2)
- Overexpression in some tumours, such as breast and gastric
- Blocked by Trastuzumab (Herceptin)
- Thalidomide (and derivatives)
- Used for blood cancers (leukaemia, lymphoma, and multiple myeloma)
- Unknown mechanism of action, likely immunosuppressive and anti-angiogenesis
- BIRTH DEFECTS! Pregnancy Category X
Problems associated with cancer chemotherapy
- Immune reactions
- Increasing individual drug resistance
- Cost
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Description
Explore the evolution of cancer chemotherapy from the 1940s to modern practices. This quiz covers key developments, types of therapies, and classifications of cytotoxic agents. Test your knowledge on historical milestones and therapeutic strategies in combating cancer.
