Anticancer Drugs Practice Questions

Q: Which type of alkylating antineoplastic drug is Lomustine?

Nitrosoureas. **Explanation:** Alkylating agents are a class of antineoplastic drugs that act by attaching alkyl groups to DNA, leading to cross-linking and strand breaks. **Lomustine (CCNU)** belongs to the **Nitrosourea** sub-class. **Why Nitrosoureas is correct:** Nitrosoureas, including **Lomustine, Carmustine (BCNU), and Semustine**, are highly lipid-soluble, non-ionized compounds. This characteristic allows them to readily cross the **blood-brain barrier (BBB)**. Consequently, they are the drugs of choice for treating primary brain tumors (e.g., glioblastoma multiforme) and meningeal leukemia. **Analysis of Incorrect Options:** * **Nitrogen mustards:** This group includes drugs like Cyclophosphamide, Ifosfamide, and Mechlorethamine. While they are alkylating agents, their chemical structure and clinical applications differ from nitrosoureas. * **Alkyl sulfonate:** The classic example is **Busulfan**, primarily used in Chronic Myeloid Leukemia (CML) and known for causing pulmonary fibrosis. * **Triazine:** This group includes **Dacarbazine and Temozolomide**. While Temozolomide also crosses the BBB, Lomustine is chemically classified specifically as a nitrosourea. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Nitrosoureas require non-enzymatic activation to form carbonium ions that alkylate DNA. * **Toxicity:** A unique feature of nitrosoureas is **delayed myelosuppression** (occurring 4–6 weeks after administration). * **Mnemonic:** Remember the "mustines" (**Car**mustine, **Lo**mustine, **Se**mustine) are **Nitrosoureas** that go to the **CNS**.

Q: Methotrexate is often used as a chemotherapeutic agent to treat patients with leukemia. This drug is effective because it inhibits cells in which phase of the cell cycle?

S phase. **Explanation:** **Mechanism of Action (Why S phase is correct):** Methotrexate (MTX) is a folate antagonist and a classic example of a **Cell Cycle Specific (CCS)** drug. It works by competitively inhibiting the enzyme **Dihydrofolate Reductase (DHFR)**. This inhibition prevents the conversion of dihydrofolate to tetrahydrofolate (the active form). Tetrahydrofolate is a crucial cofactor required for the synthesis of thymidylate and purine nucleotides. Since DNA synthesis and replication occur exclusively during the **S phase (Synthesis phase)** of the cell cycle, MTX exerts its cytotoxic effect by halting DNA production during this specific window. **Analysis of Incorrect Options:** * **G1 phase (Gap 1):** This is the pre-synthetic phase where organelles and proteins are produced. While some drugs like L-asparaginase act here, MTX does not target the metabolic processes specific to G1. * **G2 phase (Gap 2):** This phase involves the synthesis of RNA and proteins required for spindle formation. Drugs like **Bleomycin** and **Etoposide** primarily act in the G2 phase. * **M phase (Mitosis):** This involves physical cell division. Drugs that target microtubules, such as **Vinca alkaloids** (Vincristine, Vinblastine) and **Taxanes** (Paclitaxel), are specific to the M phase. **High-Yield Clinical Pearls for NEET-PG:** * **Rescue Therapy:** High-dose MTX toxicity is managed with **Leucovorin (Folinic acid)**, which bypasses the blocked DHFR enzyme to provide a source of reduced folate to healthy cells. * **Resistance:** Most common mechanism of resistance is a change in the affinity of DHFR or decreased uptake by the folate carrier. * **Adverse Effects:** Nephrotoxicity (due to crystalluria), Hepatotoxicity (cirrhosis with long-term use), and Pulmonary fibrosis. * **Other Uses:** Apart from leukemia, it is a first-line Disease-Modifying Antirheumatic Drug (DMARD) for Rheumatoid Arthritis and is used for Ectopic Pregnancy and Psoriasis.

Q: Which enzyme deficiency leads to serious side effects with 5-Fluorouracil?

Dihydropyrimidine dehydrogenase. **Explanation:** **1. Why Dihydropyrimidine dehydrogenase (DPD) is correct:** 5-Fluorouracil (5-FU) is a pyrimidine antimetabolite used in treating solid tumors (e.g., colorectal and breast cancer). **DPD is the rate-limiting enzyme responsible for the catabolism (breakdown) of over 80% of administered 5-FU** into inactive metabolites. If a patient has a genetic deficiency of DPD, 5-FU is not cleared efficiently, leading to toxic accumulation. This results in severe, potentially life-threatening side effects, including profound myelosuppression, severe mucositis, and neurotoxicity. **2. Why the other options are incorrect:** * **CYP2D6:** This is a Cytochrome P450 enzyme involved in the metabolism of drugs like Tamoxifen, codeine, and beta-blockers. It does not play a role in 5-FU metabolism. * **Uridine diphosphate (UDP):** While 5-FU is converted into active metabolites like F-dUMP and FUTP (which involve uridine pathways), the *deficiency* of UDP itself is not the clinical marker for 5-FU toxicity. (Note: Uridine triacetate is actually used as an antidote for 5-FU overdose). * **Purine:** 5-FU is a **pyrimidine** analogue, not a purine. Enzymes related to purine metabolism (like TPMT) are relevant for drugs like 6-Mercaptopurine, not 5-FU. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** 5-FU inhibits **Thymidylate Synthase**, leading to "thymineless death" of cells. * **Antidote:** **Uridine triacetate** is the specific FDA-approved antidote for 5-FU or Capecitabine overdose/toxicity. * **Hand-Foot Syndrome:** A common dermatological side effect associated with 5-FU and its prodrug, Capecitabine. * **Comparison:** While **DPD** deficiency affects 5-FU, **TPMT** (Thiopurine Methyltransferase) deficiency leads to toxicity with **6-Mercaptopurine** and **Azathioprine**.

Q: Which is the most cardiotoxic anticancer drug class?

Anthracyclines. **Explanation:** **1. Why Anthracyclines are the correct answer:** Anthracyclines (e.g., **Doxorubicin, Daunorubicin**) are notorious for causing dose-dependent, cumulative cardiotoxicity. The underlying mechanism involves the generation of **reactive oxygen species (ROS)** and the formation of iron-anthracycline complexes. These lead to lipid peroxidation of the myocardial cell membrane and damage to the sarcoplasmic reticulum. Unlike other tissues, the heart is particularly vulnerable because it has low levels of antioxidant enzymes like catalase and superoxide dismutase. This can manifest as acute arrhythmias or, more commonly, chronic **congestive heart failure (CHF)**. **2. Why other options are incorrect:** * **Alkylating agents (e.g., Cyclophosphamide):** While high doses can cause hemorrhagic cystitis (prevented by Mesna) or acute myocarditis, they are primarily known for bone marrow suppression and secondary malignancies, not chronic cardiotoxicity. * **Platinum compounds (e.g., Cisplatin):** These are primarily associated with **nephrotoxicity** and **ototoxicity**. They do not typically cause significant cardiotoxicity. * **Bisphosphonates:** These are not primary anticancer drugs but are used to treat bone metastases and hypercalcemia. Their main side effects include osteonecrosis of the jaw and esophageal irritation. **3. NEET-PG High-Yield Clinical Pearls:** * **Dexrazoxane:** An iron chelator used to prevent/reduce doxorubicin-induced cardiotoxicity. * **Monitoring:** Patients on Anthracyclines should have regular **ECHO/MUGA scans** to monitor the Left Ventricular Ejection Fraction (LVEF). * **Trastuzumab (Herceptin):** Another cardiotoxic drug (monoclonal antibody), but unlike Anthracyclines, its toxicity is usually **reversible** and not dose-dependent. * **Lifetime Dose:** The risk of CHF increases significantly once the cumulative dose of Doxorubicin exceeds **450–550 mg/m²**.

Q: A patient with Non-Hodgkin's Lymphoma (NHL) is being treated with the CHOP chemotherapy regimen. Which of the listed agents is most likely to be protective against the cardiotoxicity associated with doxorubicin?

Dexrazoxane. **Explanation:** **1. Why Dexrazoxane is the correct answer:** Doxorubicin (the ‘H’ or Hydroxydaunorubicin in the CHOP regimen) causes dose-dependent cardiotoxicity. The underlying mechanism involves the formation of **iron-anthracycline complexes** that generate reactive oxygen species (ROS), leading to lipid peroxidation and cardiomyocyte death [1]. **Dexrazoxane** is an iron-chelating agent that enters cardiac cells and interferes with iron-mediated free radical formation [1]. It also inhibits Topoisomerase IIβ, further protecting the heart. It is specifically FDA-approved to reduce the incidence and severity of cardiomyopathy associated with doxorubicin administration. **2. Why the other options are incorrect:** * **Amifostine:** A cytoprotective agent (free radical scavenger) used primarily to reduce nephrotoxicity associated with **Cisplatin** and xerostomia in radiotherapy. * **Leucovorin (Folinic Acid):** Used as a "rescue" therapy to prevent bone marrow toxicity after high-dose **Methotrexate** or to potentiate the action of 5-Fluorouracil. * **Vitamin C:** While an antioxidant, it has no proven clinical role in preventing anthracycline-induced cardiotoxicity and is not used in standard oncological protocols for this purpose. **3. NEET-PG High-Yield Pearls:** * **Doxorubicin Toxicity:** Look for "Dilated Cardiomyopathy" or "Congestive Heart Failure" in clinical vignettes [1]. * **Monitoring:** Periodic **ECHO or MUGA scans** are mandatory to monitor the Left Ventricular Ejection Fraction (LVEF) [1]. * **Cumulative Dose:** Risk increases significantly when the cumulative dose of Doxorubicin exceeds **450–550 mg/m²** [1]. * **Mnemonic for CHOP:** **C**yclophosphamide, **H**ydroxydaunorubicin (Doxorubicin), **O**ncovin (Vincristine), **P**rednisolone.

Q: Which of the following is a common side effect of cisplatin?

Vomiting. **Explanation:** **Cisplatin** is a potent platinum-based alkylating agent used for various solid tumors. It is classified as a **highly emetogenic** drug. 1. **Why Vomiting is Correct:** Cisplatin is notorious for causing severe nausea and vomiting. It triggers the release of serotonin from enterochromaffin cells in the GI tract and directly stimulates the **Chemoreceptor Trigger Zone (CTZ)** in the medulla. It causes both acute (within 24 hours) and delayed emesis. Management typically requires a combination of 5-HT3 antagonists (e.g., Ondansetron), NK1 receptor antagonists (e.g., Aprepitant), and Dexamethasone. 2. **Why Other Options are Incorrect:** * **Diarrhea:** While some chemotherapeutic agents (like Irinotecan or 5-Fluorouracil) are known for causing severe diarrhea, it is not the hallmark side effect of Cisplatin. * **Pulmonary Fibrosis:** This is the classic dose-limiting toxicity of **Bleomycin** and **Busulfan**, not Cisplatin. * **Alopecia:** While many anticancer drugs cause hair loss, it is relatively less common or less severe with Cisplatin compared to Taxanes, Doxorubicin, or Cyclophosphamide. **High-Yield Clinical Pearls for NEET-PG:** * **Dose-limiting toxicity:** Nephrotoxicity (prevented by aggressive **Amifostine** and hydration). * **Ototoxicity:** High-frequency hearing loss and tinnitus (often irreversible). * **Peripheral Neuropathy:** "Glove and stocking" distribution. * **Mnemonic:** Remember the **"3 N's"** of Cisplatin: **N**ausea/Vomiting, **N**ephrotoxicity, and **N**eurotoxicity (including Ototoxicity).

Q: Which of the following is a known side effect associated with the chemotherapeutic agent Cisplatin?

Renal failure. **Cisplatin** is a platinum-based alkylating agent widely used for solid tumors. Its most significant dose-limiting toxicity is **Nephrotoxicity (Renal Failure)**. ### 1. Why Renal Failure is Correct Cisplatin accumulates in the proximal convoluted tubule (PCT) cells of the kidney, leading to oxidative stress and apoptosis. This manifests as a decrease in GFR and an increase in serum creatinine. To prevent this, clinicians use **aggressive hydration with normal saline** and the administration of **Amifostine** (a cytoprotective free-radical scavenger). ### 2. Analysis of Incorrect Options * **A. Hemorrhagic cystitis:** This is the classic side effect of **Cyclophosphamide** and **Ifosfamide** due to the metabolite **Acrolein**. It is prevented by **MESNA**. * **C. Tympanic membrane fibrosis:** While Cisplatin causes **Ototoxicity** (high-frequency hearing loss and tinnitus), it is due to damage to the **hair cells in the Organ of Corti**, not fibrosis of the tympanic membrane. * **D. Necrotizing enterocolitis:** This is primarily a neonatal gastrointestinal emergency, not a recognized specific side effect of Cisplatin therapy. ### 3. High-Yield Clinical Pearls for NEET-PG * **Mnemonic for Cisplatin Side Effects:** "3 N's" — **N**ephrotoxicity, **N**eurotoxicity (peripheral neuropathy), and **N**ausea/vomiting (it is highly emetogenic). * **Electrolyte Imbalance:** Cisplatin frequently causes **Hypomagnesemia** and hypokalemia due to renal tubular damage. * **Drug of Choice for Vomiting:** For Cisplatin-induced emesis, the regimen of choice is a **5-HT3 antagonist (Ondansetron) + Dexamethasone + NK1 antagonist (Aprepitant).** * **Carboplatin:** A related drug that is less nephrotoxic but more **myelosuppressive** (causes thrombocytopenia).

Q: Which drug is the best treatment for estrogen-positive breast cancer?

Tamoxifen. **Explanation:** **Tamoxifen (Option A)** is the gold standard and first-line treatment for hormone receptor-positive (ER/PR+) breast cancer in both pre- and post-menopausal women. It belongs to the class of **Selective Estrogen Receptor Modulators (SERMs)**. Its mechanism involves competitive antagonism of estrogen receptors in breast tissue, thereby inhibiting the growth of estrogen-dependent cancer cells. **Analysis of Incorrect Options:** * **Clomifene (Option B):** While also a SERM, it acts primarily on the hypothalamus to block the feedback inhibition of estrogen. This increases GnRH, FSH, and LH, making it a drug of choice for **ovulation induction** in infertility, not cancer. * **Glutethimide (Option C):** This is an older sedative-hypnotic drug (similar to barbiturates) with no role in oncology. * **5-Fluorouracil (Option D):** An antimetabolite (pyrimidine analog) used in various chemotherapy regimens (e.g., CMF). While used in breast cancer, it is not specific to estrogen-positive status and is generally a second-line or adjuvant cytotoxic choice compared to targeted hormonal therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Dual Action:** Tamoxifen is an **antagonist in the breast** but an **agonist in the endometrium and bone**. * **Side Effects:** Due to its agonist effect on the uterus, it increases the risk of **endometrial carcinoma** and thromboembolism (DVT/PE). However, it helps prevent osteoporosis. * **Drug of Choice:** For post-menopausal ER+ breast cancer, **Aromatase Inhibitors** (e.g., Anastrozole, Letrozole) are now often preferred over Tamoxifen, but Tamoxifen remains the classic correct answer for general ER+ management in exams.

Q: Panitumumab is used for which of the following conditions?

Colorectal Carcinoma. **Explanation:** **Panitumumab** is a recombinant, fully humanized monoclonal antibody that targets the **Epidermal Growth Factor Receptor (EGFR)**. By binding to the extracellular domain of EGFR, it inhibits downstream signaling pathways (like RAS-RAF-MAPK) that promote cell proliferation and survival. * **Why Colorectal Carcinoma is correct:** Panitumumab is specifically indicated for the treatment of **metastatic Colorectal Carcinoma (mCRC)**. It is used in patients whose tumors express wild-type **KRAS** (non-mutated). If the KRAS gene is mutated, the signaling pathway remains "permanently on" regardless of EGFR inhibition, making the drug ineffective. **Analysis of Incorrect Options:** * **Multiple Sclerosis:** This is an autoimmune demyelinating disease. Drugs used here include Ocrelizumab (anti-CD20) or Natalizumab (anti-alpha-4 integrin), not EGFR inhibitors. * **Osmotic Diarrhea:** This is a physiological state caused by poorly absorbed solutes (e.g., lactulose or magnesium salts). It is not a clinical indication for monoclonal antibodies. * **Ascites:** This is a clinical sign of portal hypertension or malignancy. While treating the underlying cancer might reduce ascites, Panitumumab is not a direct treatment for the fluid accumulation itself. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** EGFR (ErbB1) Inhibitor. * **Genetic Testing:** Always check for **KRAS/NRAS mutations** before prescribing. It only works in **Wild-type** cases. * **Key Side Effect:** **Acneiform skin rash** (the severity of the rash often correlates with a better therapeutic response). * **Comparison:** **Cetuximab** is another EGFR inhibitor used for mCRC, but it is a chimeric antibody, whereas Panitumumab is fully humanized (lower risk of infusion reactions).

Q: Flutamide is used in which type of cancer?

Prostate. **Explanation:** **Flutamide** is a non-steroidal, competitive **androgen receptor antagonist**. Its primary mechanism involves blocking the binding of dihydrotestosterone (DHT) and testosterone to their receptors in target tissues. Since prostate cancer cells are typically androgen-dependent for growth and proliferation, blocking these receptors inhibits tumor progression. * **Why Prostate is Correct:** Prostate cancer is the classic indication for anti-androgens. Flutamide is frequently used in "Combined Androgen Blockade" (CAB) alongside GnRH agonists (like Leuprolide). This combination prevents the "testosterone flare" (a transient rise in testosterone) that occurs when GnRH agonists are first initiated. * **Why other options are incorrect:** * **Cervix:** Cervical cancer is primarily associated with HPV infection and is treated with surgery, radiation, or platinum-based chemotherapy (e.g., Cisplatin), not hormonal therapy. * **Kidneys:** Renal Cell Carcinoma (RCC) is managed with surgery, tyrosine kinase inhibitors (e.g., Sunitinib), or immunotherapy. * **Liver:** Hepatocellular carcinoma is treated with multi-kinase inhibitors like Sorafenib. **High-Yield Clinical Pearls for NEET-PG:** 1. **Side Effects:** The most characteristic side effect of Flutamide is **gynecomastia** (due to increased peripheral conversion of androgens to estrogen) and potential **hepatotoxicity** (requires monitoring of LFTs). 2. **Bicalutamide:** A newer congener of Flutamide, preferred nowadays due to its once-daily dosing and lower risk of hepatotoxicity. 3. **Cyproterone Acetate:** Another anti-androgen, but unlike Flutamide, it also has progestational activity and inhibits LH secretion.

Question 1

Which type of alkylating antineoplastic drug is Lomustine?

Accepted Answer

Nitrosoureas

Answer

Nitrogen mustards

Answer

Alkyl sulfonate

Answer

Triazine

Question 2

Methotrexate is often used as a chemotherapeutic agent to treat patients with leukemia. This drug is effective because it inhibits cells in which phase of the cell cycle?

Accepted Answer

S phase

Answer

G1 phase

Answer

G2 phase

Answer

M phase

Question 3

Which enzyme deficiency leads to serious side effects with 5-Fluorouracil?

Accepted Answer

Dihydropyrimidine dehydrogenase

Answer

CYP2D6

Answer

Uridine diphosphate

Answer

Purine

Question 4

Which is the most cardiotoxic anticancer drug class?

Accepted Answer

Anthracyclines

Answer

Alkylating agents

Answer

Platinum compounds

Answer

Bisphosphonates

Question 5

A patient with Non-Hodgkin's Lymphoma (NHL) is being treated with the CHOP chemotherapy regimen. Which of the listed agents is most likely to be protective against the cardiotoxicity associated with doxorubicin?

Accepted Answer

Dexrazoxane

Answer

Amifostine

Answer

Leucovorin

Answer

Vitamin C

Question 6

Which of the following is a common side effect of cisplatin?

Accepted Answer

Vomiting

Answer

Diarrhea

Answer

Pulmonary fibrosis

Answer

Alopecia

Question 7

Which of the following is a known side effect associated with the chemotherapeutic agent Cisplatin?

Accepted Answer

Renal failure

Answer

Hemorrhagic cystitis

Answer

Tympanic membrane fibrosis

Answer

Necrotizing enterocolitis

Question 8

Which drug is the best treatment for estrogen-positive breast cancer?

Accepted Answer

Tamoxifen

Answer

Clomifene

Answer

Glutethemide

Answer

5-FU

Question 9

Panitumumab is used for which of the following conditions?

Accepted Answer

Colorectal Carcinoma

Answer

Multiple Sclerosis

Answer

Osmotic diarrhea

Answer

Ascites

Question 10

Flutamide is used in which type of cancer?

Accepted Answer

Prostate

Answer

Cervix

Answer

Kidneys

Answer

Liver

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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