Anticancer Drugs Practice Questions

Q: Which of the following drugs act by inhibiting DNA replication?

6-Mercaptopurine. ***6-Mercaptopurine*** - This drug is a **purine analog** that acts as an **antimetabolite**, directly interfering with the **synthesis of purine nucleotides** required for DNA replication. - By inhibiting enzymes like **PRPP amidotransferase** and getting incorporated into DNA as a fraudulent nucleotide, it blocks the **de novo synthesis** pathway, preventing normal DNA replication. - This represents **direct inhibition of DNA synthesis** at the nucleotide building block level. *Mitomycin C* - This agent is an **alkylating agent** that **cross-links DNA** strands, causing DNA damage that prevents strand separation. - While it does prevent DNA replication, its mechanism is through **DNA damage and structural disruption** rather than inhibition of the DNA synthesis machinery itself. - It acts by damaging already-formed DNA rather than preventing new DNA synthesis. *Actinomycin D* - Actinomycin D is an **intercalating agent** that inserts itself between DNA base pairs, primarily **inhibiting RNA synthesis** by blocking RNA polymerase movement. - While it binds to DNA, its primary therapeutic action is on **transcription (RNA synthesis)**, not direct inhibition of DNA replication. *Asparaginase* - Asparaginase is an enzyme that **depletes asparagine** from the blood, which is an essential amino acid for certain cancer cells (e.g., leukemic cells). - Its mechanism is to starve cancer cells of asparagine, leading to **inhibition of protein synthesis**, not DNA replication.

Q: Which antineoplastic agent is known to cause hemorrhagic cystitis?

Cyclophosphamide. ***Cyclophosphamide*** - Cyclophosphamide is an **alkylating agent** that forms highly reactive metabolites, such as **acrolein**, which is excreted in the urine and causes direct irritation and damage to the bladder urothelium, leading to **hemorrhagic cystitis**. - This toxicity can be mitigated by co-administration of **mesna** (2-mercaptoethane sulfonate sodium), which inactivates acrolein in the bladder, and aggressive intravenous hydration. *Methotrexate* - Methotrexate is a **folate antagonist** primarily known for causing **myelosuppression**, **mucositis**, and **hepatotoxicity**. - While it can cause renal toxicity at high doses due to precipitation in renal tubules, it is not typically associated with hemorrhagic cystitis. *Cisplatin* - Cisplatin is a **platinum-based chemotherapy agent** with significant **nephrotoxicity** and **ototoxicity** as its dose-limiting toxicities. - It also commonly causes profound nausea and vomiting but is not a primary cause of hemorrhagic cystitis. *Vincristine* - Vincristine is a **vinca alkaloid** that interferes with microtubule formation, primarily known for causing **peripheral neuropathy** (e.g., foot drop, paresthesias, constipation due to autonomic neuropathy) and is a vesicant. - It does not typically cause hemorrhagic cystitis; its bone marrow toxicity is generally less severe compared to other chemotherapeutic agents.

Q: Which of the following drugs is not associated with significant cardiotoxicity?

Cisplatin. ***Cisplatin*** - While cisplatin is associated with various toxicities, including **nephrotoxicity** and **neurotoxicity**, significant **cardiotoxicity** (like cardiomyopathy or severe arrhythmias) is much less common compared to the other listed agents. - Its primary cardiac effects are often indirect, such as electrolyte disturbances, or less severe, making it the least cardiotoxic among the options. *5-Fluorouracil* - This drug is known to cause **coronary vasospasm**, leading to **angina** or **myocardial infarction** in some patients. - The cardiotoxicity can manifest as **ischemic events** and **arrhythmias**, particularly during or shortly after infusion. *Cyclophosphamide* - High doses of cyclophosphamide can induce **hemorrhagic myocarditis** and **congestive heart failure**, particularly in the setting of bone marrow transplantation. - It causes direct myocardial damage and can lead to rapid-onset cardiac dysfunction. *Doxorubicin* - Doxorubicin is a well-known cause of **dose-dependent cardiomyopathy**, which can lead to **irreversible heart failure**. - Its cardiotoxicity can be acute (arrhythmias, pericarditis-myocarditis syndrome) or chronic (dilated cardiomyopathy).

Q: Rituximab is used in all of the following conditions except:

Paroxysmal nocturnal hemoglobinuria. ***Paroxysmal nocturnal hemoglobinuria*** - **Eculizumab**, a C5 complement inhibitor, is the primary treatment for paroxysmal nocturnal hemoglobinuria to prevent complement-mediated hemolysis and thrombosis. - Rituximab targets CD20 B cells and would not directly address the underlying complement dysregulation in PNH. *Non-Hodgkin lymphoma* - Rituximab is a cornerstone of therapy, especially for **B-cell non-Hodgkin lymphomas**, as it targets the CD20 antigen expressed on malignant B cells. - It is often used in combination with chemotherapy regimens like **R-CHOP** (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). *Rheumatoid arthritis* - Rituximab is approved for the treatment of **moderate to severe rheumatoid arthritis** in patients who have had an inadequate response to TNF inhibitors. - It works by depleting B cells, which play a role in the autoimmune pathogenesis of RA. *Systemic lupus erythematosus* - While not officially FDA-approved for SLE, rituximab is used **off-label** in some severe, refractory cases of SLE, particularly those with significant renal or hematological involvement. - It targets B cells, which are central to autoantibody production and immune complex formation in SLE.

Q: Which chemotherapy drug functions by alkylating DNA, resulting in strand breaks and ultimately leading to cancer cell death?

Cyclophosphamide. ***Cyclophosphamide*** - **Cyclophosphamide** is an **alkylating agent** that forms covalent bonds with DNA, leading to DNA cross-linking and strand breaks. - This **DNA damage** prevents cell replication and triggers apoptosis in rapidly dividing cancer cells. *Methotrexate* - **Methotrexate** is an **antimetabolite** that inhibits **dihydrofolate reductase**, thereby blocking DNA synthesis. - Its primary mechanism is interfering with **folate metabolism**, not direct DNA alkylation. *Paclitaxel* - **Paclitaxel** is a **microtubule-stabilizing agent** that promotes microtubule assembly and prevents their disassembly. - This action blocks cell division during metaphase, but it does not involve DNA alkylation. *Vincristine* - **Vincristine** is a **vinca alkaloid** that inhibits microtubule formation by binding to tubulin. - This prevents the formation of the mitotic spindle, arresting cells in metaphase, and does not involve direct DNA modification.

Q: A patient receiving cisplatin for chemotherapy develops renal impairment. Which of the following drugs is least likely to cause nephrotoxicity?

Bleomycin. ***Bleomycin*** - **Bleomycin** is an antineoplastic agent known for its primary toxicity to the **lungs (pulmonary fibrosis)** and skin, with nephrotoxicity being very rare [1]. - Its mechanism of action involves DNA strand scission, but its elimination is primarily renal without causing significant damage to the **kidneys**. *Cisplatin* - **Cisplatin** is a highly nephrotoxic agent, causing acute tubular necrosis, and is a well-known cause of **renal impairment** in chemotherapy patients [2]. - The patient in the stem is described as receiving cisplatin and developing renal impairment, indicating its potent nephrotoxic potential. *Carboplatin* - **Carboplatin** is an analog of cisplatin and is also **nephrotoxic**, although its nephrotoxicity is generally less severe than that of cisplatin [2]. - It is still a significant concern, and regular monitoring of kidney function is required during treatment. *Methotrexate* - **Methotrexate**, especially at high doses, can cause **acute kidney injury** due to the precipitation of its metabolites in the renal tubules, leading to obstruction. - This nephrotoxicity can be mitigated by adequate hydration and **urinary alkalinization**.

Q: Hand and foot syndrome is caused by which of the following drugs?

5-Fluorouracil (5-FU). ***5-Fluorouracil (5-FU)*** - **Hand-foot syndrome (HFS)**, also known as palmar-plantar erythrodysesthesia, is a common and dose-limiting dermatological toxicity of 5-FU. - It presents with **redness, swelling, pain, and blistering** on the palms of the hands and soles of the feet. *Vincristine* - This drug is primarily associated with **neurotoxicity**, causing peripheral neuropathy with symptoms like paresthesias, weakness, and loss of reflexes. - It does not typically cause hand-foot syndrome, which is a specific dermatological reaction. *Cisplatin* - Cisplatin is known for its **nephrotoxicity** (kidney damage), ototoxicity (hearing loss), and severe nausea and vomiting. - While it can cause some dermatological side effects, hand-foot syndrome is not a characteristic or common adverse event associated with cisplatin. *Azathioprine* - Azathioprine is an immunosuppressant often used in autoimmune diseases and transplant patients, and its main side effects include **myelosuppression** (bone marrow suppression), liver dysfunction, and gastrointestinal issues. - It is not implicated in causing hand-foot syndrome.

Q: A patient with breast cancer is administered a chemotherapy agent that stabilizes microtubules, preventing their disassembly during mitosis. Which drug is used?

Paclitaxel. ***Paclitaxel*** - **Paclitaxel** is a **taxane** drug that works by binding to **beta-tubulin subunits**, stabilizing microtubules and preventing their depolymerization. - This stabilization arrests cells in the **G2/M phase of mitosis**, leading to apoptotic cell death in rapidly dividing cancer cells. *Doxorubicin* - **Doxorubicin** is an **anthracycline antibiotic** that intercalates into DNA, leading to strand breaks and inhibition of **topoisomerase II**. - Its primary mechanism is DNA damage, not direct microtubule stabilization. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** that forms covalent bonds with DNA, causing cross-linking and strand breaks. - This DNA damage interferes with replication and transcription, leading to cell cycle arrest and apoptosis. *Vincristine* - **Vincristine** is a **vinca alkaloid** that binds to **tubulin dimers**, preventing their polymerization into microtubules. - Unlike paclitaxel, which stabilizes microtubules, vincristine inhibits their formation and promotes disassembly.

Q: Which enzyme is inhibited by the drug methotrexate during cancer treatment?

Dihydrofolate reductase. ***Dihydrofolate reductase*** - **Methotrexate** is a **folate analog** that competitively inhibits **dihydrofolate reductase (DHFR)**, an enzyme essential for converting dihydrofolate to **tetrahydrofolate**. - Inhibition of DHFR blocks the synthesis of **purine nucleotides** and **thymidylate**, thereby impairing DNA synthesis and cell proliferation, particularly in rapidly dividing cancer cells. *DNA polymerase* - **DNA polymerase** is involved in **DNA replication and repair**, but it is not the primary target of methotrexate. - While inhibition of DNA synthesis is an effect of methotrexate, it occurs upstream through the depletion of nucleotide precursors rather than direct inhibition of DNA polymerase. *Ribonucleotide reductase* - **Ribonucleotide reductase** is an enzyme responsible for converting **ribonucleotides to deoxyribonucleotides**, which are necessary for DNA synthesis. - While inhibiting this enzyme would also affect DNA synthesis, it is primarily targeted by drugs like **hydroxyurea**, not methotrexate. *Thymidylate synthase* - **Thymidylate synthase** is an enzyme that catalyzes the methylation of **deoxyuridylate (dUMP)** to **deoxythymidylate (dTMP)**, a crucial precursor for DNA synthesis. - While methotrexate ultimately reduces the supply of **N5, N10-methylenetetrahydrofolate**, a cofactor for thymidylate synthase, it does not directly inhibit the enzyme itself; rather, drugs like **5-fluorouracil** target this enzyme.

Question 1

Which of the following statements is not true about tamoxifen?

Accepted Answer

Tamoxifen is useful in post-menopausal and aromatase inhibitors in premenopausal patients.

Answer

It can cause endometrial carcinoma.

Answer

It is used for visceral metastasis.

Answer

Dose is 20 mg for 5 years.

Question 2

Which of the following drugs act by inhibiting DNA replication?

Accepted Answer

6-Mercaptopurine

Answer

Mitomycin C

Answer

Actinomycin D

Answer

Asparaginase

Question 3

Which antineoplastic agent is known to cause hemorrhagic cystitis?

Accepted Answer

Cyclophosphamide

Answer

Methotrexate

Answer

Cisplatin

Answer

Vincristine

Question 4

Which of the following drugs is not associated with significant cardiotoxicity?

Accepted Answer

Cisplatin

Answer

5-Fluorouracil

Answer

Cyclophosphamide

Answer

Doxorubicin

Question 5

Rituximab is used in all of the following conditions except:

Accepted Answer

Paroxysmal nocturnal hemoglobinuria

Answer

Rheumatoid arthritis

Answer

Systemic lupus erythematosus

Answer

Non-Hodgkin lymphoma

Question 6

Which chemotherapy drug functions by alkylating DNA, resulting in strand breaks and ultimately leading to cancer cell death?

Accepted Answer

Cyclophosphamide

Answer

Methotrexate

Answer

Paclitaxel

Answer

Vincristine

Question 7

A patient receiving cisplatin for chemotherapy develops renal impairment. Which of the following drugs is least likely to cause nephrotoxicity?

Accepted Answer

Bleomycin

Answer

Cisplatin

Answer

Carboplatin

Answer

Methotrexate

Question 8

Hand and foot syndrome is caused by which of the following drugs?

Accepted Answer

5-Fluorouracil (5-FU)

Answer

Vincristine

Answer

Cisplatin

Answer

Azathioprine

Question 9

A patient with breast cancer is administered a chemotherapy agent that stabilizes microtubules, preventing their disassembly during mitosis. Which drug is used?

Accepted Answer

Paclitaxel

Answer

Doxorubicin

Answer

Cyclophosphamide

Answer

Vincristine

Question 10

Which enzyme is inhibited by the drug methotrexate during cancer treatment?

Accepted Answer

Dihydrofolate reductase

Answer

DNA polymerase

Answer

Ribonucleotide reductase

Answer

Thymidylate synthase

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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