Anticancer Drugs — MCQs

Anticancer Drugs Indian Medical PG Practice Questions and MCQs

Question 471: Which of the following drug classes is known to cause sterility?

A. Vinca alkaloids
B. Alkylating agents (Correct Answer)
C. Antimetabolites
D. Actinomycin D

Explanation: **Explanation:** **Alkylating agents** (e.g., Cyclophosphamide, Busulfan, Procarbazine) are the most common class of antineoplastics associated with **gonadal toxicity and permanent sterility**. These drugs are cell-cycle non-specific and work by forming covalent bonds with DNA, leading to cross-linking and strand breaks. Because they target rapidly dividing cells, they significantly damage the germinal epithelium of the testes (causing oligospermia/azoospermia) and the ovarian follicles (leading to premature ovarian failure). The risk is dose-dependent and higher in post-pubertal patients. **Analysis of Incorrect Options:** * **Vinca Alkaloids (e.g., Vincristine):** These are M-phase specific drugs that inhibit microtubule polymerization. Their primary dose-limiting toxicity is **neurotoxicity** (peripheral neuropathy) rather than permanent sterility. * **Antimetabolites (e.g., Methotrexate, 5-FU):** These S-phase specific drugs interfere with DNA synthesis. While they can cause transient infertility during treatment, they are rarely associated with permanent gonadal failure compared to alkylating agents. * **Actinomycin D:** An antitumor antibiotic that intercalates into DNA. Its major toxicities include bone marrow suppression and GI upset, but it is not a classic cause of permanent sterility. **NEET-PG High-Yield Pearls:** * **Busulfan:** Specifically known for causing "Busulfan Lung" (pulmonary fibrosis) and severe marrow suppression before bone marrow transplant. * **Cyclophosphamide:** Associated with **Hemorrhagic Cystitis** (prevented by **MESNA** and hydration). * **Procarbazine:** Has high leukemogenic potential and can cause a **Disulfiram-like reaction** with alcohol. * **Ovarian protection:** GnRH agonists are sometimes used during chemotherapy to "quiet" the ovaries and reduce the risk of premature menopause.

Question 472: Which of the following drugs is NOT commonly used in the treatment of Non-Hodgkin lymphoma?

A. Doxorubicin
B. Cyclophosphamide
C. Vincristine
D. Cisplatin (Correct Answer)

Explanation: **Explanation:** The standard first-line treatment for most types of Non-Hodgkin Lymphoma (NHL), particularly Diffuse Large B-Cell Lymphoma (DLBCL), is the **CHOP** or **R-CHOP** regimen. **Why Cisplatin is the Correct Answer:** While **Cisplatin** is a potent platinum-based alkylating agent, it is **not** part of the standard primary induction therapy for NHL. It is typically reserved for **salvage therapy** (e.g., DHAP or ESHAP regimens) in patients with relapsed or refractory disease. In contrast, the drugs listed in options A, B, and C are the core components of the standard frontline CHOP regimen. **Analysis of Incorrect Options:** * **Cyclophosphamide (C):** An alkylating agent (nitrogen mustard) that forms DNA cross-links. It is the "C" in CHOP. * **Doxorubicin (H):** An anthracycline antibiotic (Hydroxydaunorubicin) that inhibits Topoisomerase II and generates free radicals. It is the "H" in CHOP. * **Vincristine (O):** A vinca alkaloid that inhibits microtubule polymerization (Oncovin). It is the "O" in CHOP. * *(Note: The "P" in CHOP stands for Prednisolone).* **High-Yield Clinical Pearls for NEET-PG:** * **R-CHOP:** The addition of **Rituximab** (anti-CD20 monoclonal antibody) has significantly improved survival in CD20+ B-cell lymphomas. * **Dose-Limiting Toxicities:** * **Cyclophosphamide:** Hemorrhagic cystitis (prevented by **MESNA**). * **Doxorubicin:** Cardiotoxicity (dilated cardiomyopathy). * **Vincristine:** Peripheral neuropathy (areflexia/paresthesia) and paralytic ileus. * **Cisplatin:** Nephrotoxicity and Ototoxicity. * **Burkitt Lymphoma:** Often requires more intensive regimens like Hyper-CVAD rather than standard CHOP.

Question 473: Which drug arrests mitosis in metaphase?

A. Busulfan
B. 5-fluorouracil
C. Vinca Alkaloids (Correct Answer)
D. Methotrexate

Explanation: **Explanation:** The correct answer is **Vinca Alkaloids (Option C)**. **Mechanism of Action:** Vinca alkaloids (e.g., Vincristine, Vinblastine) are **cell cycle-specific** agents that act during the **M-phase (Mitosis)**. They bind to tubulin and inhibit its polymerization into microtubules. This prevents the formation of the mitotic spindle, which is essential for chromosome separation. Consequently, the cell cannot progress beyond metaphase, leading to **mitotic arrest** and subsequent apoptosis. **Analysis of Incorrect Options:** * **A. Busulfan:** An **Alkylating agent** that works by cross-linking DNA strands. It is cell cycle-nonspecific and is notably used in chronic myeloid leukemia (CML) and bone marrow ablation. * **B. 5-Fluorouracil (5-FU):** An **Antimetabolite (Pyrimidine analog)** that inhibits thymidylate synthase. It acts specifically during the **S-phase** (DNA synthesis) of the cell cycle. * **C. Methotrexate:** A **Folate antagonist** that inhibits dihydrofolate reductase (DHFR). Like 5-FU, it is **S-phase specific**, preventing the synthesis of DNA, RNA, and proteins. **High-Yield Clinical Pearls for NEET-PG:** * **Vincristine vs. Vinblastine Toxicity:** Remember the mnemonic: **"Vincristine blasts the Nerves"** (Peripheral neuropathy is the dose-limiting toxicity) and **"Vinblastine blasts the Bone marrow"** (Bone marrow suppression is the dose-limiting toxicity). * **Taxanes (e.g., Paclitaxel):** These also act on the M-phase but have the *opposite* mechanism—they **stabilize** microtubules (preventing depolymerization), "freezing" the cell in mitosis. * **Vinca Alkaloids** are fatal if administered intrathecally; they must only be given intravenously.

Question 474: What is the drug of choice for Choriocarcinoma?

A. Methotrexate (Correct Answer)
B. Actinomycin-D
C. Vincristine
D. 6-thioguanine

Explanation: **Explanation:** **Methotrexate (MTX)** is the drug of choice for **Choriocarcinoma** (a highly malignant trophoblastic tumor). The underlying medical concept is that choriocarcinoma cells are exquisitely sensitive to folate antagonists. Methotrexate works by inhibiting the enzyme **Dihydrofolate Reductase (DHFR)**, preventing the conversion of dihydrofolate to tetrahydrofolate. This halts DNA synthesis and cell proliferation. In low-risk gestational trophoblastic neoplasia (GTN), MTX is used as monotherapy (often with Leucovorin rescue), achieving nearly 100% cure rates. **Analysis of Incorrect Options:** * **B. Actinomycin-D (Dactinomycin):** While highly effective and used as a second-line agent or in combination (EMA-CO regimen) for high-risk cases, it is generally considered the alternative to Methotrexate, not the primary drug of choice for initial single-agent therapy. * **C. Vincristine:** This is a vinca alkaloid that inhibits microtubule assembly. It is part of the EMA-CO regimen for high-risk choriocarcinoma but is never used as a first-line monotherapy. * **D. 6-Thioguanine:** This is a purine analog primarily used in the treatment of Acute Myeloid Leukemia (AML). It has no significant role in the management of choriocarcinoma. **High-Yield Clinical Pearls for NEET-PG:** * **Leucovorin (Folinic Acid) Rescue:** Used to minimize MTX toxicity by providing a source of reduced folate that bypasses DHFR. * **Monitoring:** Therapeutic success in choriocarcinoma is uniquely monitored using **serum β-hCG levels**. * **Other uses of MTX:** Ectopic pregnancy (medical management), Rheumatoid Arthritis (Disease-modifying antirheumatic drug - DMARD), and Psoriasis. * **Side Effects:** Hepatotoxicity, pulmonary fibrosis, and mucositis.

Question 475: Which of the following medications are essential for ameliorating the toxicity of pemetrexed?

A. Folinic acid and vitamin B12 (Correct Answer)
B. Folic acid and vitamin B12
C. Vitamin B6 and Vitamin B1
D. Folic acid and dexamethasone

Explanation: **Explanation:** **Pemetrexed** is a multi-targeted antifolate antineoplastic agent that inhibits three key enzymes in folate metabolism: thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). **1. Why Option A is Correct:** The primary toxicities of pemetrexed are hematologic (neutropenia, anemia) and gastrointestinal (mucositis). These toxicities are significantly exacerbated by high baseline levels of homocysteine and methylmalonic acid, which indicate functional folate and Vitamin B12 deficiency. To reduce these life-threatening toxicities without compromising the drug's efficacy, patients must be pre-treated with **Folinic acid (Leucovorin)** and **Vitamin B12**. *Note:* While some protocols use folic acid, **Folinic acid** is the active form (5-formyl THF) that bypasses the inhibited DHFR enzyme more effectively to protect healthy cells. **2. Why Other Options are Incorrect:** * **Option B:** While folic acid is used in some guidelines, the combination of Folinic acid and B12 is the gold standard for immediate metabolic bypass. * **Option C:** Vitamin B6 (Pyridoxine) is used to prevent Palmar-Plantar Erythrodysesthesia (Hand-Foot Syndrome) caused by 5-FU or Capecitabine, and B1 (Thiamine) is not specific to pemetrexed toxicity. * **Option D:** Dexamethasone is indeed given with pemetrexed, but specifically to prevent the **cutaneous rash** associated with the drug, not the systemic metabolic toxicity addressed by folate/B12. **High-Yield Clinical Pearls for NEET-PG:** * **Pemetrexed Indication:** First-line treatment for non-squamous Non-Small Cell Lung Cancer (NSCLC) and Mesothelioma. * **Pre-medication Protocol:** 1. **Folinic/Folic Acid:** Start 1 week before the first dose. 2. **Vitamin B12:** Intramuscular injection every 3 cycles. 3. **Dexamethasone:** Taken for 3 days (day before, day of, and day after infusion) to prevent skin rashes. * **Avoid NSAIDs:** Patients should avoid NSAIDs with short half-lives 2 days before and after pemetrexed administration due to the risk of decreased renal clearance.

Question 476: Which of the following is an indication for the use of folinic acid?

A. Prophylaxis of neural tube defects in the offspring of women receiving anticonvulsant medications
B. Counteracting toxicity of high-dose methotrexate therapy (Correct Answer)
C. Pernicious anemia
D. Anemia associated with renal failure

Explanation: ### Explanation **Correct Option: B. Counteracting toxicity of high-dose methotrexate therapy** **Mechanism of Action:** Methotrexate (MTX) is a folate antagonist that inhibits the enzyme **dihydrofolate reductase (DHFR)**. This inhibition prevents the conversion of dihydrofolate to tetrahydrofolate (THF), the active form of folic acid required for DNA synthesis. **Folinic acid (Leucovorin)** is a reduced form of folate (5-formyl-THF) that does not require DHFR for its activity. When administered after high-dose MTX, it "bypasses" the metabolic block, providing a source of active folate to healthy cells. This process is known as **"Leucovorin Rescue,"** and it prevents lethal bone marrow and gastrointestinal toxicity. **Analysis of Incorrect Options:** * **Option A:** Prophylaxis of neural tube defects requires **Folic acid**, not folinic acid. Folic acid is sufficient for supplementation in pregnancy as DHFR activity is normal. * **Option C:** Pernicious anemia is caused by **Vitamin B12 deficiency**. While folate can temporarily improve the hematological profile, it fails to treat the underlying neurological damage and is therefore contraindicated as monotherapy. * **Option D:** Anemia of renal failure is primarily due to a deficiency of **Erythropoietin**, which is the standard treatment. **High-Yield NEET-PG Pearls:** * **Leucovorin/Folinic Acid** is also used to **potentiate** the action of **5-Fluorouracil (5-FU)** in colorectal cancer by stabilizing the binding of 5-dUMP to thymidylate synthase. * **Glucarpidase** is an alternative used for MTX toxicity in patients with renal failure (it enzymatically degrades MTX). * **Methotrexate Toxicity:** Common side effects include myelosuppression, mucositis, and nephrotoxicity (due to crystalluria). Always ensure adequate hydration and urinary alkalinization.

Question 477: All of the following are true about rituximab except?

A. Chimeric monoclonal antibody against CD-20 B cell antigen
B. Most common side effect is infusion reaction
C. First FDA drug approved for resistant lymphomas
D. Dose-independent pharmacokinetics (Correct Answer)

Explanation: **Explanation:** Rituximab is a landmark therapeutic agent in oncology and rheumatology. The correct answer is **D** because Rituximab exhibits **dose-dependent (non-linear) pharmacokinetics**, not dose-independent. Its clearance is influenced by the "tumor burden"; as CD-20 receptors are saturated and B-cells are depleted, the clearance rate decreases and the half-life increases. **Analysis of Options:** * **Option A (True):** Rituximab is a **chimeric** (mouse/human) monoclonal antibody. It specifically targets the **CD-20 antigen** found on the surface of normal and malignant B-lymphocytes. * **Option B (True):** The **most common side effect** is an **infusion-related reaction** (fever, chills, rigors), typically occurring during the first infusion due to cytokine release. Pre-medication with acetaminophen and antihistamines is standard practice. * **Option C (True):** Rituximab holds the historical distinction of being the **first monoclonal antibody approved by the FDA (1997)** for the treatment of cancer, specifically for relapsed or refractory low-grade B-cell non-Hodgkin's lymphoma. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mechanism of Action:** Causes B-cell lysis via Antibody-Dependent Cellular Cytotoxicity (ADCC), Complement-Dependent Cytotoxicity (CDC), and apoptosis. 2. **Major Risk:** It can cause **Reactivation of Hepatitis B**. Screening for HBsAg and anti-HBc is mandatory before starting therapy. 3. **Rare but Fatal Side Effect:** Progressive Multifocal Leukoencephalopathy (PML) due to JC virus reactivation. 4. **Clinical Uses:** NHL, CLL, Rheumatoid Arthritis (refractory to TNF inhibitors), Wegener’s Granulomatosis, and Pemphigus Vulgaris.

Question 478: Which of the following anticancer drugs has a high emetogenic potential?

A. Chlorambucil
B. Vincristine
C. 6-Mercaptopurine
D. Cisplatin (Correct Answer)

Explanation: **Explanation:** **Cisplatin** is the correct answer because it is classified as a **highly emetogenic** chemotherapy agent (Level 5, >90% frequency of emesis without prophylaxis). The underlying mechanism involves the release of serotonin (5-HT) from enterochromaffin cells in the GI tract and the stimulation of the Chemoreceptor Trigger Zone (CTZ) in the area postrema. Due to its high emetic potential, patients receiving Cisplatin require aggressive prophylactic antiemetic therapy, typically a "triple regimen" consisting of a 5-HT3 antagonist (e.g., Ondansetron), a NK1 receptor antagonist (e.g., Aprepitant), and Dexamethasone. **Analysis of Incorrect Options:** * **Chlorambucil (A):** An alkylating agent used primarily in CLL. It is administered orally and has **low emetogenic potential**. * **Vincristine (B):** A vinca alkaloid that inhibits microtubule assembly. It is notorious for peripheral neuropathy but has **minimal emetogenic potential**. * **6-Mercaptopurine (C):** A purine antimetabolite used in ALL maintenance therapy. It is associated with bone marrow suppression and hepatotoxicity but has **low emetogenic potential**. **High-Yield Clinical Pearls for NEET-PG:** * **Cisplatin Toxicity Profile:** Remember the "3 Ns"—**N**ephrotoxicity (prevented by aggressive hydration/Amifostine), **N**eurotoxicity (peripheral neuropathy), and **N**ausea/Vomiting (highly emetogenic). It also causes **Ototoxicity** (high-frequency hearing loss). * **Highly Emetogenic Drugs:** Apart from Cisplatin, other high-risk drugs include Cyclophosphamide (>1500 mg/m²), Dacarbazine, and Anthracycline/Cyclophosphamide combinations (AC regimen). * **Drug of Choice for Cisplatin-induced vomiting:** 5-HT3 antagonists (Ondansetron) are the mainstay for acute emesis, while Aprepitant is preferred for delayed emesis.

Question 479: Fluorouracil undergoes in vivo chemical changes resulting in a covalent complex bound to both thymidylate synthase and methylene-tetrahydrofolate. What type of inhibition is responsible for the subsequent blockage of deoxythymidilate formation and cell division?

A. Allosteric inhibition
B. Competitive inhibition
C. Irreversible inhibition (Correct Answer)
D. Noncovalent inhibition

Explanation: **Explanation:** **Mechanism of Action (Why C is correct):** 5-Fluorouracil (5-FU) is a pyrimidine analog that acts as a "suicide inhibitor." Once inside the cell, it is converted to **5-FdUMP** (5-fluorodeoxyuridine monophosphate). This metabolite acts as a false substrate and forms a stable, **covalent ternary complex** with the enzyme **Thymidylate Synthase (TS)** and the cofactor **5,10-methylene tetrahydrofolate**. Because the bond is covalent and the enzyme is permanently inactivated, this is classified as **Irreversible Inhibition**. This prevents the conversion of dUMP to dTMP, leading to a "thymineless death" of the cell. **Analysis of Incorrect Options:** * **A. Allosteric inhibition:** This involves binding to a site other than the active site to induce a conformational change. 5-FU binds directly to the active site. * **B. Competitive inhibition:** While 5-FdUMP competes for the active site initially, the formation of a permanent covalent bond makes the inhibition irreversible (non-competitive in kinetics over time), as it cannot be reversed by increasing substrate concentration. * **D. Noncovalent inhibition:** The hallmark of 5-FU’s action is the formation of a **covalent** bond; noncovalent interactions are reversible and weaker. **NEET-PG High-Yield Pearls:** * **Rescue Agent:** Leucovorin (folinic acid) is administered with 5-FU not to reduce toxicity, but to **potentiate** its efficacy by stabilizing the ternary complex. * **Rate-limiting Enzyme:** Dihydropyrimidine dehydrogenase (DPD) degrades 5-FU. Patients with **DPD deficiency** are at high risk of severe 5-FU toxicity (pancytopenia, mucosal ulceration). * **Specific Toxicity:** Hand-foot syndrome (palmar-plantar erythrodysesthesia) is a characteristic side effect.

Question 480: All of the following anticancer drugs are cell cycle non-specific except?

A. Cisplatin
B. Vincristine (Correct Answer)
C. Mitomycin-C
D. Cyclophosphamide

Explanation: ### Explanation The classification of anticancer drugs based on cell cycle kinetics is a high-yield topic for NEET-PG. Drugs are categorized into **Cell Cycle Specific (CCS)** agents, which act on specific phases (e.g., M or S phase), and **Cell Cycle Non-Specific (CCNS)** agents, which act on both resting and dividing cells. **Why Vincristine is the Correct Answer:** Vincristine is a **Vinca alkaloid** that acts specifically during the **M-phase (Mitosis)**. It binds to tubulin and inhibits its polymerization into microtubules, preventing the formation of the mitotic spindle. This leads to mitotic arrest in metaphase. Since it targets a specific phase, it is a **Cell Cycle Specific (CCS)** drug. **Analysis of Incorrect Options:** * **Cisplatin (Option A):** A platinum coordination complex that cross-links DNA. It is **CCNS**, although it shows maximum toxicity during the G1 and S phases. * **Mitomycin-C (Option C):** An antitumor antibiotic that acts as an alkylating agent. It is **CCNS** and is particularly effective against hypoxic tumor cells. * **Cyclophosphamide (Option D):** An alkylating agent (nitrogen mustard) that causes DNA cross-linking. Alkylating agents are the classic examples of **CCNS** drugs because they damage DNA regardless of the cell cycle stage. **High-Yield Clinical Pearls for NEET-PG:** * **CCS Drugs:** Remember the mnemonic **"M-S-G"**: **M**-phase (Vincas, Taxanes), **S**-phase (Antimetabolites like Methotrexate, 5-FU), and **G2**-phase (Bleomycin). * **CCNS Drugs:** Alkylating agents, Platinum compounds, and Anthracyclines (Doxorubicin). * **Vincristine Side Effect:** Distinctive for **peripheral neuropathy** (paresthesia, loss of reflexes) and **constipation** (paralytic ileus), but notably **bone marrow sparing**.

Practice by Chapter

Principles of Cancer Chemotherapy

Practice Questions

Alkylating Agents

Practice Questions

Antimetabolites

Practice Questions

Antitumor Antibiotics

Practice Questions

Plant Alkaloids

Practice Questions

Topoisomerase Inhibitors

Practice Questions

Hormonal Agents

Practice Questions

Targeted Therapy

Practice Questions

Immunotherapy

Practice Questions

Management of Chemotherapy Side Effects

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free