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1. What is the mechanism of action of cyclophosphamide in cancer
treatment?
a) It inhibits DNA synthesis by cross-linking DNA strands
b) It blocks the cell cycle by interfering with microtubule formation
c) It induces apoptosis by activating caspases
d) It stimulates the immune system by releasing cytokines
Answer: A. Cyclophosphamide is an alkylating agent that forms covalent
bonds between adjacent DNA strands, preventing DNA replication and
transcription.
Rationale: B, C and D are mechanisms of action of other classes of
anticancer drugs, such as taxanes, anthracyclines and immunotherapy
agents.
2. What are the main adverse effects of cyclophosphamide?
a) Nausea, vomiting and diarrhea
b) Hemorrhagic cystitis, bone marrow suppression and alopecia
c) Cardiotoxicity, hepatotoxicity and nephrotoxicity
d) Peripheral neuropathy, mucositis and skin rash
Answer: B. Cyclophosphamide can cause hemorrhagic cystitis due to the
formation of acrolein, a toxic metabolite that irritates the bladder mucosa.
It can also cause bone marrow suppression, leading to anemia, leukopenia
and thrombocytopenia, and alopecia due to damage to hair follicles.
Rationale: A, C and D are adverse effects of other classes of anticancer
drugs, such as platinum compounds, anthracyclines and taxanes.
3. How can hemorrhagic cystitis be prevented or treated in patients
receiving cyclophosphamide?
a) By administering mesna, a sulfhydryl compound that binds to acrolein
b) By administering allopurinol, a xanthine oxidase inhibitor that reduces
uric acid production
c) By administering amifostine, a cytoprotective agent that scavenges free
radicals
d) By administering leucovorin, a folinic acid derivative that enhances
DNA repair
Answer: A. Mesna is a specific antidote for cyclophosphamide-induced
hemorrhagic cystitis. It forms a complex with acrolein in the urine,
rendering it inactive and less toxic to the bladder mucosa.
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