Anticancer Drugs Practice Questions

Q: Which of the following anticancer drugs is cell cycle specific?

Bleomycin. ### Explanation Anticancer drugs are broadly classified into **Cell Cycle-Specific (CCS)** agents, which act on cells during a particular phase (e.g., S or M phase), and **Cell Cycle-Non-Specific (CCNS)** agents, which act on cells regardless of their phase in the cycle. **Why Bleomycin is Correct:** Bleomycin is a unique glycopeptide antibiotic that is **Cell Cycle-Specific**, acting primarily in the **G2 phase**. It works by binding to DNA and producing free radicals (superoxide and hydroxyl radicals) that cause single- and double-strand breaks. Because it targets a specific phase of the cell cycle, its efficacy is schedule-dependent. **Why the Other Options are Incorrect:** * **Dactinomycin (Actinomycin D):** This is an antitumor antibiotic that intercalates into DNA. It is considered **CCNS**, although it shows some increased activity in the G1 phase. * **Mitomycin C:** This is a potent alkylating agent that causes DNA cross-linking. Like most alkylating agents, it is **CCNS**. * **Daunorubicin:** Along with Doxorubicin, this belongs to the Anthracycline class. While they have maximum toxicity during the S phase, they are traditionally classified as **CCNS** because they intercalate DNA and inhibit Topoisomerase II throughout the cycle. **High-Yield NEET-PG Pearls:** * **Bleomycin Toxicity:** The most characteristic side effect is **Pulmonary Fibrosis**. Unlike most cytotoxic drugs, it is **not bone marrow suppressant** (it is "myelosuppressive-sparing"). * **G2 Phase Specificity:** Bleomycin is the classic example of a G2-specific drug. * **M-Phase Specific:** Vinca alkaloids (Vincristine/Vinblastine) and Taxanes (Paclitaxel). * **S-Phase Specific:** Antimetabolites (Methotrexate, 5-FU, Cytarabine).

Q: Which of the following is a cell cycle non-specific antineoplastic drug?

None of the above. ### Explanation The correct answer is **None of the above** because all three drugs listed (Vincristine, Methotrexate, and Bleomycin) are **Cell Cycle Specific (CCS)** agents. #### 1. Understanding the Concept Antineoplastic drugs are classified into two categories based on their kinetics: * **Cell Cycle Specific (CCS):** These drugs act only on specific phases of the cell cycle (e.g., S-phase or M-phase). They are most effective against rapidly dividing tumors. * **Cell Cycle Non-Specific (CCNS):** These drugs act on cells regardless of the phase they are in (including the resting G0 phase). Examples include **Alkylating agents** (Cyclophosphamide, Busulfan) and **Anthracyclines** (Doxorubicin). #### 2. Analysis of Options * **Vincristine (Option A):** This is a Vinca alkaloid that inhibits tubulin polymerization. It is highly specific for the **M-phase** (Mitosis), causing metaphase arrest. * **Methotrexate (Option B):** An Antimetabolite (folate antagonist) that inhibits Dihydrofolate Reductase (DHFR). It acts specifically during the **S-phase** (DNA synthesis). * **Bleomycin (Option C):** Unlike most antitumor antibiotics which are CCNS, Bleomycin is unique as it is CCS, acting primarily in the **G2 phase** (and late S-phase) by causing oxidative DNA strand scission. #### 3. NEET-PG High-Yield Pearls * **Mnemonic for CCS drugs:** "**V**ery **B**usy **M**etabolizing **S**pecialists" (**V**inca alkaloids - M phase; **B**leomycin - G2 phase; **M**ethotrexate/Antimetabolites - S phase; **S**teroids - G1 phase). * **CCNS Drugs:** Remember **"ABCD"**—**A**lkylating agents, **B**enzene derivatives (Nitrosoureas), **C**isplatin, and **D**actinomycin/Doxorubicin. * **Clinical Note:** CCNS drugs generally follow linear dose-response curves (the more drug given, the more cells killed), whereas CCS drugs are "schedule-dependent" and reach a plateau in cell killing.

Q: A 35-year-old patient with carcinoma of the lung and a past history of lung disease is to be treated. Which of the following anticancer drugs should be avoided?

Bleomycin. **Explanation:** The correct answer is **Bleomycin**. **1. Why Bleomycin is the correct answer:** Bleomycin is a glycopeptide antibiotic used as a chemotherapeutic agent that acts by causing DNA strand scission. Its most notorious and dose-limiting toxicity is **Pulmonary Fibrosis**. The drug concentrates in the lungs because the enzyme that inactivates it (bleomycin hydrolase) is found in very low concentrations in pulmonary tissue. In a patient with a pre-existing history of lung disease, the risk of developing fatal interstitial pneumonitis and subsequent fibrosis is significantly increased. Therefore, it is strictly avoided or used with extreme caution in such patients. **2. Why the other options are incorrect:** * **Vinblastine:** A Vinca alkaloid that inhibits microtubule assembly. Its primary dose-limiting toxicity is **bone marrow suppression** (myelosuppression), not pulmonary toxicity. * **Mithramycin (Plicamycin):** Primarily used for refractory hypercalcemia and Paget’s disease. Its major toxicities are **thrombocytopenia** and hepatotoxicity. * **Adriamycin (Doxorubicin):** An anthracycline antibiotic. Its classic dose-limiting toxicity is **Cardiotoxicity** (dilated cardiomyopathy), not lung disease. **3. NEET-PG High-Yield Pearls:** * **Bleomycin:** "Lung-sparing" for the bone marrow (causes minimal myelosuppression) but "Marrow-sparing" for the lungs (causes maximal lung damage). * **Monitoring:** Patients on Bleomycin require serial **Pulmonary Function Tests (PFTs)**, specifically looking for a decrease in DLCO (Diffusion Capacity of the Lung for Carbon Monoxide). * **Other drugs causing Pulmonary Fibrosis:** Busulfan, Methotrexate, and Amiodarone. * **Dose Limit:** The risk of fibrosis increases significantly when the cumulative dose of Bleomycin exceeds **400-450 units**.

Q: What is the mechanism of action of imatinib mesylate?

Blocks the action of the chimeric fusion protein BCR-ABL.. **Explanation:** **1. Why Option C is Correct:** Imatinib mesylate is a revolutionary targeted therapy known as a **selective tyrosine kinase inhibitor (TKI)**. It specifically targets the **BCR-ABL** tyrosine kinase, a chimeric fusion protein resulting from the **Philadelphia chromosome (t[9;22])**. In Chronic Myeloid Leukemia (CML), this protein is constitutively active, leading to uncontrolled cell proliferation. Imatinib works by acting as a **competitive inhibitor at the ATP-binding site** of the BCR-ABL enzyme, preventing the phosphorylation of substrates and effectively "turning off" the oncogenic signal. **2. Why Other Options are Incorrect:** * **Options A & B:** P-glycoprotein (P-gp) is an efflux pump associated with multi-drug resistance (MDR) in cancer cells. While Imatinib is a substrate for P-gp (which can lead to drug resistance), its primary therapeutic mechanism of action is not the modulation of this protein. * **Option D:** Imatinib is a **competitive** inhibitor, not a non-competitive one. It competes directly with ATP for the binding pocket on the kinase domain. **3. NEET-PG High-Yield Clinical Pearls:** * **Drug of Choice (DOC):** Imatinib is the first-line treatment for **Chronic Myeloid Leukemia (CML)** and **Gastrointestinal Stromal Tumors (GIST)**. * **GIST Mechanism:** In GIST, it inhibits the **c-KIT (CD117)** tyrosine kinase. * **Other Targets:** It also inhibits the Platelet-Derived Growth Factor Receptor (**PDGFR**). * **Side Effects:** The most characteristic side effect is **periorbital edema** (fluid retention). Others include nausea, muscle cramps, and diarrhea. * **Resistance:** Resistance often develops due to point mutations in the BCR-ABL kinase domain (e.g., **T315I mutation**), which may require second-generation TKIs like **Dasatinib** or **Nilotinib**.

Q: High dose Methotrexate is used for the treatment of which of the following conditions?

Osteosarcoma. **Explanation:** **Methotrexate (MTX)** is a folate antagonist that inhibits the enzyme **dihydrofolate reductase (DHFR)**, leading to a depletion of intracellular folate pools and inhibition of DNA synthesis. **Why Osteosarcoma is correct:** High-dose Methotrexate (HDMTX), typically defined as doses >500 mg/m², is a cornerstone in the treatment of **Osteosarcoma**. Because osteosarcoma cells often have poor drug uptake or high levels of DHFR, massive doses are required to create a concentration gradient sufficient to bypass resistance mechanisms. This regimen necessitates **Leucovorin Rescue** (Folinic acid) to protect healthy cells from lethal hematological and GI toxicity. **Why other options are incorrect:** * **Rhabdomyosarcoma:** Primarily treated with the **VAC regimen** (Vincristine, Actinomycin-D, and Cyclophosphamide). * **Retinoblastoma:** Management usually involves local therapy or systemic chemotherapy using **VEC** (Vincristine, Etoposide, and Carboplatin). * **Ewing’s Sarcoma:** The standard protocol is the **VDC/IE regimen** (Vincristine, Doxorubicin, Cyclophosphamide alternating with Ifosfamide and Etoposide). **High-Yield Clinical Pearls for NEET-PG:** 1. **Leucovorin Rescue:** Must be started 24 hours after MTX to provide an alternative source of reduced folate for normal cells. 2. **Hydration & Alkalinization:** To prevent **nephrotoxicity** (MTX precipitates in acidic urine), patients must be hydrated and given sodium bicarbonate to keep urine pH >7.0. 3. **Glucarpidase:** An enzyme used as an antidote for MTX toxicity in patients with renal failure. 4. **Resistance:** Occurs via decreased polyglutamation, decreased uptake (reduced folate carrier), or gene amplification of DHFR.

Q: What is the primary effect of tamoxifen?

Increased risk of endometrial carcinoma. **Explanation:** Tamoxifen is a **Selective Estrogen Receptor Modulator (SERM)**. Its primary mechanism involves acting as a competitive antagonist at estrogen receptors in breast tissue, making it a cornerstone in the treatment of hormone receptor-positive breast cancer. **1. Why Option A is correct:** The "selective" nature of Tamoxifen means it acts as an **agonist** (estrogen-like effect) in certain tissues, specifically the **uterus** and bone. By stimulating the estrogen receptors in the endometrium, it promotes endometrial hyperplasia, which significantly increases the risk of **endometrial carcinoma**. This is a classic high-yield association for medical exams. **2. Why the other options are incorrect:** * **Option B:** Tamoxifen does not significantly decrease the risk of ovarian cancer; its primary protective role is in breast tissue. * **Option C:** Cardiotoxicity is a hallmark side effect of **Anthracyclines** (e.g., Doxorubicin) and **Trastuzumab**, not Tamoxifen. Tamoxifen is actually associated with a slightly increased risk of thromboembolism (DVT/PE). * **Option D:** Because Tamoxifen acts as an **agonist in bone**, it increases bone mineral density and actually **decreases the risk of osteoporosis** in postmenopausal women. **NEET-PG High-Yield Pearls:** * **Drug of Choice:** Tamoxifen is the DOC for breast cancer in **premenopausal** women. (Aromatase inhibitors are preferred in postmenopausal women). * **Side Effects:** Hot flashes (most common), venous thromboembolism, and endometrial cancer. * **Raloxifene:** Another SERM that is an antagonist in both breast and uterus; therefore, it does **not** increase the risk of endometrial cancer but is used primarily for osteoporosis.

Q: Which of the following agents inhibits microtubule formation?

Vincristine. **Explanation:** The correct answer is **Vincristine**. This question tests your understanding of drugs acting on the mitotic spindle (M-phase of the cell cycle). **1. Why Vincristine is Correct:** Vincristine belongs to the **Vinca Alkaloids** (derived from *Catharanthus roseus*). Its mechanism of action involves binding to **tubulin dimers**, which **prevents their polymerization** into microtubules. This inhibition of microtubule formation leads to "mitotic arrest" in the metaphase, eventually causing cell death. **2. Why the Other Options are Incorrect:** * **Paclitaxel:** While it also acts on microtubules, its mechanism is the opposite. It **promotes polymerization** and stabilizes microtubules, preventing their *disassembly* (de-polymerization). This creates "frozen" microtubules. * **Etoposide:** This is a **Topoisomerase II inhibitor**. It acts in the S and G2 phases by causing DNA strand breaks. * **Irinotecan:** This is a **Topoisomerase I inhibitor**, primarily used in colorectal cancer. It prevents the religation of single-strand DNA breaks. **3. High-Yield Clinical Pearls for NEET-PG:** * **Vincristine Side Effects:** Characterized by **Peripheral Neuropathy** (paresthesia, loss of reflexes) and paralytic ileus. Notably, it is **bone marrow sparing** (minimal myelosuppression). * **Vinblastine Side Effect:** Unlike Vincristine, its dose-limiting toxicity is **Bone Marrow Suppression** (*"Blast" blasts the bone marrow*). * **Taxanes (Paclitaxel):** Common side effects include peripheral neuropathy and hypersensitivity reactions (pre-medicate with steroids/antihistamines). * **Mnemonic:** **V**incristine **P**revents polymerization; **T**axanes **T**ighten (stabilize) the polymer.

Q: Which of the following drugs is used in the adjuvant setting for carcinoma of the colon?

Oxaliplatin. **Explanation:** **Oxaliplatin** is the correct answer because it is a cornerstone of **adjuvant chemotherapy** for Stage III (and high-risk Stage II) colon cancer. The standard adjuvant regimens are **FOLFOX** (5-Fluorouracil, Leucovorin, and Oxaliplatin) or **CAPOX** (Capecitabine and Oxaliplatin). Adjuvant therapy aims to eliminate micrometastases after surgical resection to reduce the risk of recurrence. **Analysis of Incorrect Options:** * **Bevacizumab (Option A):** This is a VEGF inhibitor (angiogenesis inhibitor). While highly effective in the **metastatic** (palliative) setting, clinical trials (like NSABP C-08) showed it provides no survival benefit in the adjuvant setting for colon cancer. * **Cetuximab (Option B):** An EGFR inhibitor used specifically for **metastatic** colorectal cancer in patients with **KRAS wild-type** tumors. Similar to Bevacizumab, it has failed to show benefit in adjuvant trials. * **Irinotecan (Option C):** A Topoisomerase I inhibitor. It is a key component of the **FOLFIRI** regimen used for **metastatic** disease. However, adding Irinotecan to adjuvant 5-FU (IFL regimen) did not improve outcomes compared to 5-FU alone and increased toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Dose-limiting toxicity of Oxaliplatin:** Peripheral sensory neuropathy (often triggered or exacerbated by **cold exposure**). * **Mechanism:** Platinum compound that forms intra-strand DNA cross-links. * **5-Fluorouracil (5-FU):** Always the "backbone" of colon cancer therapy; its action is enhanced by **Leucovorin** (folinic acid), which stabilizes the binding of 5-dUMP to thymidylate synthase. * **Microsatellite Instability (MSI-H):** Patients with Stage II colon cancer and MSI-H have a good prognosis and generally do *not* benefit from adjuvant 5-FU monotherapy.

Q: Thalidomide is used in the treatment of all EXCEPT:

Malaria. **Explanation:** Thalidomide is a potent immunomodulatory and anti-angiogenic drug. It acts by inhibiting **Tumor Necrosis Factor-alpha (TNF-α)** and modulating T-cell responses. While it was historically withdrawn due to severe teratogenicity, it has been repurposed for several specific clinical conditions. **Why Malaria is the correct answer:** Thalidomide has **no role** in the treatment of Malaria. Malaria is caused by *Plasmodium* parasites and requires antiprotozoal agents (like Artemisinin-based combination therapy or Chloroquine). Thalidomide does not possess any antiparasitic properties. **Analysis of other options:** * **Multiple Myeloma:** Thalidomide (often in combination with Dexamethasone) is a first-line agent. Its anti-angiogenic properties inhibit the blood supply to malignant plasma cells and induce apoptosis. * **DLE (Discoid Lupus Erythematosus):** Thalidomide is highly effective in refractory cases of DLE and cutaneous lupus due to its ability to suppress UV-induced TNF-α production in the skin. * **AML (Acute Myeloid Leukemia):** Though less common than its use in Myeloma, Thalidomide and its analogs (Lenalidomide) are used in certain subtypes of AML and Myelodysplastic Syndromes (MDS) to inhibit leukemic cell proliferation. **High-Yield Clinical Pearls for NEET-PG:** 1. **Teratogenicity:** The most famous side effect is **Phocomelia** (seal-like limbs). It is a Category X drug. 2. **Drug of Choice:** Thalidomide is the drug of choice for **Erythema Nodosum Leprosum (ENL)**, a Type 2 lepra reaction. 3. **Side Effects:** Apart from teratogenicity, it causes **peripheral neuropathy** (often irreversible) and increased risk of **thromboembolism**. 4. **Mechanism:** It binds to a protein called **Cereblon**, which is part of an E3 ubiquitin ligase complex.

Question 1

Which of the following anticancer drugs is cell cycle specific?

Accepted Answer

Bleomycin

Answer

Dactinomycin

Answer

Mitomycin C

Answer

Daunorubicin

Question 2

Which of the following is a cell cycle non-specific antineoplastic drug?

Accepted Answer

None of the above

Answer

Vincristine

Answer

Methotrexate

Answer

Bleomycin

Question 3

A 35-year-old patient with carcinoma of the lung and a past history of lung disease is to be treated. Which of the following anticancer drugs should be avoided?

Accepted Answer

Bleomycin

Answer

Vinblastine

Answer

Mithramycin

Answer

Adriamycin

Question 4

What is the mechanism of action of imatinib mesylate?

Accepted Answer

Blocks the action of the chimeric fusion protein BCR-ABL.

Answer

Increases the metabolism of P-glycoprotein.

Answer

Blocks the action of P-glycoprotein.

Answer

Non-competitive inhibition of the ATP binding site.

Question 5

High dose Methotrexate is used for the treatment of which of the following conditions?

Accepted Answer

Osteosarcoma

Answer

Rhabdomyosarcoma

Answer

Retinoblastoma

Answer

Ewing's sarcoma

Question 6

What is the primary effect of tamoxifen?

Accepted Answer

Increased risk of endometrial carcinoma

Answer

Decreased risk of ovarian cancer

Answer

Causes cardiotoxicity

Answer

Increased risk of osteoporosis

Question 7

A 55-year-old male patient complains of an abnormal growth on his right cheek. The patient has a history of tobacco chewing for 30 years. Radiologic findings reveal an 8x8 cm fungating mass invading the maxilla and mandible on the right side. Histologic findings are suggestive of squamous cell carcinoma. Which of the following statements regarding the treatment of this condition is NOT true?

Accepted Answer

Topoisomerase inhibitors promote the unwinding of parental DNA strands and prevent replication.

Answer

The drugs used are designed to block DNA replication.

Answer

Methotrexate and 5-fluorouracil block nucleotide synthesis.

Answer

The drugs used for cancer therapy inhibit the enzymes that participate in replication.

Question 8

Which of the following agents inhibits microtubule formation?

Accepted Answer

Vincristine

Answer

Paclitaxel

Answer

Etoposide

Answer

Irinotecan

Question 9

Which of the following drugs is used in the adjuvant setting for carcinoma of the colon?

Accepted Answer

Oxaliplatin

Answer

Bevacizumab

Answer

Cetuximab

Answer

Irinotecan

Question 10

Thalidomide is used in the treatment of all EXCEPT:

Accepted Answer

Malaria

Answer

Multiple myeloma

Answer

DLE

Answer

AML

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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