Anticancer Drugs Practice Questions

Q: A patient with tumor lysis syndrome (TLS) is taking allopurinol. Which laboratory value should the nurse monitor to determine the effectiveness of the medication?

Uric acid level. ### Explanation **Correct Answer: D. Uric acid level** **Mechanism and Rationale:** Tumor Lysis Syndrome (TLS) occurs due to the rapid breakdown of malignant cells, leading to the release of intracellular contents into the bloodstream. This results in hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. **Allopurinol** is a **xanthine oxidase inhibitor**; it prevents the conversion of hypoxanthine and xanthine into uric acid. Since the primary therapeutic goal of allopurinol in TLS is to prevent and reduce the formation of uric acid to avoid urate nephropathy, monitoring the **serum uric acid level** is the direct way to assess the drug's effectiveness. **Analysis of Incorrect Options:** * **A. Blood urea nitrogen (BUN):** While BUN monitors renal function (which can be impaired by uric acid crystals), it is a non-specific marker and does not directly reflect the pharmacological action of allopurinol. * **B. Serum phosphate:** Hyperphosphatemia is a feature of TLS, but allopurinol has no effect on phosphate metabolism. Phosphate levels are managed via phosphate binders or hydration. * **C. Serum potassium:** Hyperkalemia is the most dangerous electrolyte abnormality in TLS. However, allopurinol does not lower potassium levels; this requires insulin/dextrose, calcium gluconate, or ion-exchange resins. **NEET-PG High-Yield Pearls:** * **Drug of Choice for Prophylaxis:** Allopurinol is used for the *prevention* of hyperuricemia in TLS. * **Rasburicase:** For *established* hyperuricemia or high-risk patients, Rasburicase (recombinant urate oxidase) is preferred as it metabolizes existing uric acid into highly soluble **allantoin**. * **Drug Interaction:** Allopurinol inhibits the metabolism of **6-Mercaptopurine (6-MP)** and **Azathioprine**. If co-administered, the dose of these cytotoxic drugs must be reduced by 50–75% to prevent toxicity.

Q: Which is the most commonly used cardiotoxic anticancer drug?

Doxorubicin. **Explanation:** **Doxorubicin** (an Anthracycline antibiotic) is the most notorious and commonly used anticancer drug associated with cardiotoxicity. The underlying mechanism involves the generation of **superoxide free radicals** and iron-dependent lipid peroxidation, which damages the myocardial cell membrane. Since the heart has low levels of protective enzymes like catalase and glutathione peroxidase, it is particularly vulnerable. Cardiotoxicity manifests in two forms: 1. **Acute:** Transient ECG changes (arrhythmias). 2. **Chronic:** Dose-dependent **Dilated Cardiomyopathy (DCM)** leading to Congestive Heart Failure (CHF). This risk increases significantly when the cumulative dose exceeds 550 mg/m². **Analysis of Incorrect Options:** * **Vincristine:** Primarily known for **Peripheral Neuropathy** (stocking-glove anesthesia) and paralytic ileus. It is a spindle poison that inhibits microtubule assembly. * **L-Asparaginase:** Most commonly associated with **Acute Pancreatitis**, hyperglycemia, and clotting factor deficiencies (hypofibrinogenemia). * **Paclitaxel:** Its dose-limiting toxicity is **Myelosuppression** and peripheral neuropathy. While it can cause transient bradycardia, it is not the "most common" cardiotoxic agent compared to Doxorubicin. **High-Yield Clinical Pearls for NEET-PG:** * **Dexrazoxane:** An iron chelator used to prevent/reduce Doxorubicin-induced cardiotoxicity. * **Monitoring:** Periodic **Echocardiography (MUGA scan)** to monitor Left Ventricular Ejection Fraction (LVEF) is mandatory for patients on Anthracyclines. * **Liposomal Doxorubicin:** A formulation developed to reduce cardiac uptake and decrease toxicity.

Q: Alkylating drugs attach an alkyl group to which position of guanine?

N7. **Explanation:** **Mechanism of Action:** Alkylating agents (e.g., Cyclophosphamide, Chlorambucil) are cell cycle-nonspecific drugs that act by forming highly reactive carbonium ion intermediates. These intermediates form covalent bonds with electron-rich nucleophilic sites on DNA bases. The **N7 position of Guanine** is the most nucleophilic (electron-dense) site in DNA, making it the primary target for alkylation. **Why N7 is Correct:** When an alkyl group attaches to the N7 position of guanine, it leads to: 1. **Cross-linking:** Formation of intra-strand or inter-strand bridges (especially with bifunctional alkylators), which prevents DNA strand separation during replication. 2. **Base-pairing errors:** Guanine may mispair with Thymine. 3. **Depurination:** The imidazole ring destabilizes, leading to excision of the guanine base and subsequent DNA strand breakage. **Why Other Options are Incorrect:** * **N3 of Guanine:** While alkylation can occur at the N3 position of Adenine, it is not the preferred or most common site for Guanine. * **N5:** This is not a standard site for DNA alkylation by these agents. * **N9:** The N9 position of guanine is the site where the base attaches to the deoxyribose sugar (forming the N-glycosidic bond), making it unavailable for alkylation in a DNA polymer. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** N7 of Guanine (Primary target). * **Other targets:** N1 and N3 of Adenine, N3 of Cytosine. * **Cyclophosphamide:** A prodrug activated by Cytochrome P450 in the liver. Its metabolite **Acrolein** causes hemorrhagic cystitis, which is prevented by **MESNA** (Mercaptoethane sulfonate) and aggressive hydration. * **Resistance:** Often occurs due to increased production of Glutathione or enhanced DNA repair enzymes (e.g., MGMT).

Q: A young male was diagnosed with acute myeloid leukemia and successfully completed induction chemotherapy. Two months later, he presents with bilateral pedal edema and dyspnea on exertion (waking up multiple times due to breathlessness). Which of the following anticancer drugs is most likely responsible for these symptoms?

Doxorubicin. ### Explanation The clinical presentation of bilateral pedal edema, dyspnea on exertion, and paroxysmal nocturnal dyspnea (waking up breathless) points toward **Congestive Heart Failure (CHF)**. In a patient treated for Acute Myeloid Leukemia (AML), this is a classic manifestation of **Anthracycline-induced cardiotoxicity**. **1. Why Doxorubicin is correct:** Doxorubicin (an Anthracycline) causes cardiotoxicity through the generation of **iron-dependent free radicals** (superoxide anions) that cause lipid peroxidation of the myocardial membranes. Since the heart has low levels of protective enzymes like catalase, it is highly susceptible. This toxicity is **dose-dependent and cumulative**. It typically presents as dilated cardiomyopathy leading to heart failure months after treatment. **2. Why other options are incorrect:** * **Cisplatin:** Primarily known for **Nephrotoxicity** (prevented by aggressive hydration/Amifostine) and Ototoxicity. It does not typically cause heart failure. * **Methotrexate:** Associated with **Myelosuppression**, Mucositis, and Hepatotoxicity. High doses can cause nephrotoxicity due to crystalluria. * **Vincristine:** Its hallmark side effect is **Peripheral Neuropathy** (paresthesia, loss of deep tendon reflexes, and autonomic dysfunction like constipation). It is "bone marrow sparing." **3. High-Yield Clinical Pearls for NEET-PG:** * **Monitoring:** Periodic **Echocardiography** or MUGA scans to monitor Left Ventricular Ejection Fraction (LVEF) is mandatory. * **Prevention:** **Dexrazoxane** (an iron chelator) is used to reduce the risk of doxorubicin-induced cardiotoxicity. * **Cumulative Dose:** The risk of CHF increases significantly once the cumulative dose of Doxorubicin exceeds **550 mg/m²**. * **Histology:** On biopsy, look for "Myofibrillar loss and cytoplasmic vacuolization."

Q: Which anticancer drug belongs to the class of inorganic metal complexes?

Cisplatin. ### Explanation **Correct Answer: B. Cisplatin** **Mechanism and Classification:** Cisplatin is the prototype of the **platinum coordination complexes**, which are inorganic metal complexes. Unlike organic molecules, cisplatin consists of a central platinum atom surrounded by two ammonia molecules and two chloride atoms in a *cis* configuration. * **Mechanism of Action:** It acts as a cell-cycle non-specific alkylating-like agent. Inside the cell, chloride ions are displaced by water, forming a reactive species that binds to DNA (primarily at the N7 position of guanine). This creates **intrastrand cross-links**, leading to DNA bending, inhibition of replication, and apoptosis. **Analysis of Incorrect Options:** * **A. Dacarbazine:** An organic alkylating agent belonging to the **Triazene** group. It is a prodrug activated in the liver to MTIC, used primarily in melanoma and Hodgkin lymphoma. * **C. Methotrexate:** A classic **Antimetabolite**. It is a folate analogue that inhibits the enzyme dihydrofolate reductase (DHFR), thereby arresting DNA synthesis. * **D. Vincristine:** A **Vinca Alkaloid** derived from the periwinkle plant (*Catharanthus roseus*). It is a microtubule inhibitor that binds to tubulin and prevents polymerization (M-phase specific). **High-Yield Clinical Pearls for NEET-PG:** * **Toxicity Profile:** Cisplatin is notorious for "the three Ns": **N**ephrotoxicity (prevented by aggressive hydration and Amifostine), **N**eurotoxicity (peripheral neuropathy), and severe **N**ausea/vomiting (highly emetogenic). It is also **Ototoxic**. * **Indications:** It is the cornerstone of treatment for solid tumors, especially testicular, ovarian, and lung cancers. * **Resistance:** Often occurs due to increased DNA repair or increased intracellular levels of glutathione.

Q: All are dihydrofolate reductase antagonists, EXCEPT?

Cytosine arabinoside. **Explanation:** The question asks to identify the drug that does **not** inhibit the enzyme **Dihydrofolate Reductase (DHFR)**. **1. Why Cytosine Arabinoside (Ara-C) is the correct answer:** Cytosine arabinoside is a **pyrimidine antimetabolite**. Its mechanism of action involves being phosphorylated into its active form (ara-CTP), which then inhibits **DNA polymerase** and gets incorporated into DNA, leading to chain termination. It does not interfere with the folic acid pathway or DHFR. **2. Why the other options are incorrect (DHFR Inhibitors):** These drugs act by competitively inhibiting DHFR, preventing the conversion of dihydrofolate to tetrahydrofolate, which is essential for DNA synthesis. * **Methotrexate:** A potent DHFR inhibitor used in cancer chemotherapy and as a disease-modifying antirheumatic drug (DMARD). * **Pyrimethamine:** An antiprotozoal agent used primarily in the treatment of toxoplasmosis and malaria. * **Pentamidine:** An antiprotozoal drug used for *Pneumocystis jirovecii* pneumonia; it possesses multiple mechanisms, one of which includes DHFR inhibition. **High-Yield Clinical Pearls for NEET-PG:** * **Selective Toxicity:** Trimethoprim (antibacterial) and Pyrimethamine (antiprotozoal) have a higher affinity for microbial DHFR, whereas Methotrexate is highly specific for human DHFR. * **Rescue Therapy:** Leucovorin (folinic acid) is used to "rescue" normal cells from Methotrexate toxicity because it bypasses the DHFR step. * **Mnemonic for DHFR Inhibitors:** "**P**yrimethamine, **M**ethotrexate, **P**rimethoprim, **P**roguanil, **P**entamidine" (The **5 P's**). * **Cytosine Arabinoside** is the most effective single agent for inducing remission in **Acute Myeloid Leukemia (AML)**.

Q: All of the following can potentially be cured by chemotherapy, except?

Chondrosarcoma. **Explanation:** The core concept behind the curability of cancers with chemotherapy lies in the **Growth Fraction**. Chemotherapeutic agents primarily target rapidly dividing cells. Cancers with a high growth fraction (fast-growing) are generally highly chemosensitive, whereas slow-growing tumors with a low growth fraction are often chemoresistant. **Why Chondrosarcoma is the Correct Answer:** Chondrosarcoma is a malignant tumor of cartilage. It is characterized by a **low growth fraction**, slow progression, and poor vascularity. These tumors are notoriously **resistant to both chemotherapy and radiotherapy**. The primary and often only curative treatment modality for chondrosarcoma is wide surgical excision. **Analysis of Incorrect Options:** * **Hodgkin’s Lymphoma:** One of the biggest success stories in oncology. With regimens like ABVD (Adriamycin, Bleomycin, Vinblastine, Dacarbazine), it has a very high cure rate (up to 80-90%). * **Acute Lymphoblastic Leukemia (ALL):** This is a highly aggressive, fast-growing malignancy. Because the cells divide rapidly, they are exquisitely sensitive to chemotherapy. It is potentially curable, especially in the pediatric population. * **Wilms’ Tumor (Nephroblastoma):** A common pediatric renal tumor that is highly responsive to a combination of surgery and chemotherapy (e.g., Actinomycin D and Vincristine), boasting high survival and cure rates. **NEET-PG High-Yield Pearls:** 1. **Highly Chemocurable Tumors:** Choriocarcinoma (most sensitive), Hodgkin’s Lymphoma, ALL, Wilms’ Tumor, Germ cell tumors (Testicular cancer), and Burkitt’s Lymphoma. 2. **Chemoresistant Tumors:** Chondrosarcoma, Pancreatic Cancer, Malignant Melanoma, and Renal Cell Carcinoma (RCC). 3. **Gompertzian Growth:** As tumors grow larger, their growth fraction decreases, making them less sensitive to chemotherapy; hence, early intervention is key.

Q: Which drug is used for HER-2/neu positive breast cancer?

Trastuzumab. ### Explanation **Correct Answer: B. Trastuzumab** **Mechanism and Rationale:** Trastuzumab is a recombinant humanized monoclonal antibody specifically designed to target the **HER-2/neu (ErbB2)** receptor, a member of the Epidermal Growth Factor Receptor (EGFR) family. Approximately 20–30% of breast cancers overexpress this receptor, leading to aggressive tumor growth and poor prognosis. Trastuzumab binds to the extracellular domain of HER-2, inducing cell cycle arrest and mediating antibody-dependent cellular cytotoxicity (ADCC). **Analysis of Incorrect Options:** * **A. Imatinib:** A tyrosine kinase inhibitor (TKI) primarily targeting **BCR-ABL** (Philadelphia chromosome), c-KIT, and PDGFR. It is the first-line treatment for Chronic Myeloid Leukemia (CML) and Gastrointestinal Stromal Tumors (GIST). * **C. Erlotinib:** A small molecule TKI that targets **EGFR (ErbB1/HER1)**. It is primarily used in non-small cell lung cancer (NSCLC) with specific EGFR mutations and pancreatic cancer. * **D. Cetuximab:** A monoclonal antibody targeting **EGFR (ErbB1)**. It is used in the treatment of KRAS wild-type metastatic colorectal cancer and head and neck squamous cell carcinomas. **High-Yield Clinical Pearls for NEET-PG:** * **Cardiotoxicity:** The most significant side effect of Trastuzumab is **cardiac dysfunction** (decreased LVEF/heart failure). Unlike anthracyclines (Doxorubicin), Trastuzumab-induced cardiotoxicity is usually **reversible** and not dose-dependent. * **Combination Warning:** Avoid concurrent administration of Trastuzumab and Anthracyclines due to a synergistic increase in cardiotoxicity. * **Other HER-2 Drugs:** **Pertuzumab** (inhibits dimerization) and **Lapatinib** (a dual TKI targeting both EGFR and HER-2) are also used in HER-2 positive breast cancer.

Q: Which of the following drugs does not act on tubulin?

Bleomycin. **Explanation:** The correct answer is **Bleomycin**. The question tests your knowledge of drugs that target the microtubule system versus those that damage DNA directly. **1. Why Bleomycin is the correct answer:** Bleomycin is a **cytotoxic antibiotic** that acts by a completely different mechanism. It binds to DNA and chelates metal ions (like ferrous iron), leading to the formation of free radicals (superoxide and hydroxyl radicals). These radicals cause **single and double-strand DNA breaks**, leading to cell cycle arrest in the **G2 phase**. It does not interact with tubulin or microtubules. **2. Why the other options are incorrect:** * **Colchicine:** This is an anti-inflammatory drug used in gout. It inhibits **tubulin polymerization** (prevents the assembly of microtubules), leading to the inhibition of leukocyte migration. * **Vincristine:** A Vinca alkaloid that also inhibits **tubulin polymerization**. By binding to tubulin, it prevents the formation of the mitotic spindle, causing cell cycle arrest in the **M phase**. * **Paclitaxel:** A Taxane that acts by **enhancing tubulin polymerization**. It stabilizes microtubules and prevents their disassembly (depolymerization), resulting in "frozen" spindles that inhibit mitosis. **Clinical Pearls for NEET-PG:** * **Bleomycin Toxicity:** The most significant side effect is **Pulmonary Fibrosis** (due to a lack of the enzyme bleomycin hydrolase in the lungs). It is notably **bone marrow sparing**. * **Vincristine Toxicity:** Characterized by **peripheral neuropathy** (areflexia, paresthesia) and paralytic ileus. * **Paclitaxel Toxicity:** Common side effects include **neutropenia** and hypersensitivity reactions (often premedicated with steroids/antihistamines). * **Cell Cycle Specificity:** Vincas and Taxanes are **M-phase specific**, while Bleomycin is **G2-phase specific**.

Question 1

A patient with tumor lysis syndrome (TLS) is taking allopurinol. Which laboratory value should the nurse monitor to determine the effectiveness of the medication?

Accepted Answer

Uric acid level

Answer

Blood urea nitrogen (BUN)

Answer

Serum phosphate

Answer

Serum potassium

Question 2

Which is the most commonly used cardiotoxic anticancer drug?

Accepted Answer

Doxorubicin

Answer

Vincristine

Answer

L-Asparginase

Answer

Paclitaxol

Question 3

Alkylating drugs attach an alkyl group to which position of guanine?

Accepted Answer

N7

Answer

N3

Answer

N5

Answer

N9

Question 4

A young male was diagnosed with acute myeloid leukemia and successfully completed induction chemotherapy. Two months later, he presents with bilateral pedal edema and dyspnea on exertion (waking up multiple times due to breathlessness). Which of the following anticancer drugs is most likely responsible for these symptoms?

Accepted Answer

Doxorubicin

Answer

Cisplatin

Answer

Methotrexate

Answer

Vincristine

Question 5

Which anticancer drug belongs to the class of inorganic metal complexes?

Accepted Answer

Cisplatin

Answer

Dacarbazine

Answer

Methotrexate

Answer

Vincristine

Question 6

All are dihydrofolate reductase antagonists, EXCEPT?

Accepted Answer

Cytosine arabinoside

Answer

Methotrexate

Answer

Pentamidine

Answer

Pyrimethamine

Question 7

All of the following can potentially be cured by chemotherapy, except?

Accepted Answer

Chondrosarcoma

Answer

Hodgkin's lymphoma

Answer

Acute lymphoblastic leukemia (ALL)

Answer

Wilms' tumor

Question 8

Which drug is used for HER-2/neu positive breast cancer?

Accepted Answer

Trastuzumab

Answer

Imatinib

Answer

Erlotinib

Answer

Cetuximab

Question 9

Which of the following drugs does not act on tubulin?

Accepted Answer

Bleomycin

Answer

Colchicine

Answer

Paclitaxel

Answer

Vincristine

Question 10

What is the drug of choice for palliative treatment of pancreatic carcinoma?

Accepted Answer

Gemcitabine

Answer

Paclitaxel

Answer

Methotrexate

Answer

FOLFOX regimen

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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