Anticancer Drugs Practice Questions

Q: All of the following are true about paclitaxel except?

Obtained from E. coli. **Explanation:** **Why Option D is the Correct Answer (The Exception):** Paclitaxel is a **natural product**, not a recombinant protein derived from bacteria. It was originally isolated from the bark of the **Pacific Yew tree (*Taxus brevifolia*)**. Modern production primarily utilizes semi-synthetic processes starting from precursors found in the needles of the European Yew (*Taxus baccata*). Drugs obtained from *E. coli* are typically recombinant proteins like L-asparaginase or insulin, making this statement false. **Analysis of Other Options:** * **Option A:** This describes the unique mechanism of action of Taxanes. Unlike Vinca alkaloids (which prevent polymerization), Paclitaxel **binds to the β-tubulin subunit**, promoting and **stabilizing microtubule assembly**. This prevents depolymerization, freezing the cell in the M-phase (mitotic spindle poison). * **Option B:** Paclitaxel is a broad-spectrum agent. It is a first-line treatment for **ovarian cancer** (often with Carboplatin) and is highly effective in advanced **breast, lung, and cervical cancers**. * **Option C:** **Myelosuppression** (specifically neutropenia) is the dose-limiting toxicity. **Alopecia** is almost universal with taxane therapy. **NEET-PG High-Yield Pearls:** * **Adverse Effect:** Paclitaxel is formulated in Cremophor EL, which often causes **hypersensitivity reactions**. Pre-treatment with dexamethasone and H1/H2 blockers is mandatory. * **Nab-paclitaxel:** An albumin-bound formulation that reduces hypersensitivity risks. * **Neurotoxicity:** Peripheral neuropathy (stocking-glove pattern) is a common side effect. * **Mnemonic:** "Taxanes **T**ighten the microtubules; Vincas **V**aporize them."

Q: Melphalan is used in which of the following conditions?

Multiple myeloma. **Explanation:** **Melphalan** is a nitrogen mustard derivative and a potent **alkylating agent**. It works by forming covalent bonds with DNA, specifically at the N7 position of guanine, leading to DNA cross-linking and subsequent apoptosis of rapidly dividing cells [1]. 1. **Why Multiple Myeloma is correct:** Melphalan is a cornerstone in the treatment of **Multiple Myeloma** [2]. It is used both in standard chemotherapy regimens (often combined with Prednisone) and in high doses as a conditioning agent prior to **Autologous Stem Cell Transplantation (ASCT)**. Its high efficacy against plasma cells makes it the drug of choice for this condition. 2. **Why other options are incorrect:** * **Wilm’s Tumour:** Primarily treated with a combination of Actinomycin D, Vincristine, and sometimes Doxorubicin. * **Neuroblastoma:** Management typically involves Cyclophosphamide, Cisplatin, Etoposide, and Vincristine. * **Retinoblastoma:** Often managed with systemic or intra-arterial chemotherapy using Vincristine, Etoposide, and Carboplatin (VEC regimen). **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic:** Remember **"M"** for **M**elphalan and **"M"**ultiple **"M"**yeloma. * **Mechanism:** It is a cell cycle non-specific (CCNS) alkylating agent. * **Toxicity:** Like other nitrogen mustards, its dose-limiting toxicity is **bone marrow suppression** (myelosuppression) [2]. It also carries a risk of secondary malignancies (leukemogenic potential) with long-term use. * **Other uses:** It is occasionally used in Ovarian cancer and as part of Regional Perfusion for Malignant Melanoma.

Q: Which agent activates natural killer cells and is useful in renal cell carcinoma?

Aldesleukin. Explanation: 1. Why Aldesleukin is correct: Aldesleukin is a recombinant form of Interleukin-2 (IL-2). Its primary mechanism involves promoting the proliferation and differentiation of T-cells and activating Natural Killer (NK) cells and Lymphokine-Activated Killer (LAK) cells [1]. These activated immune cells mount a potent anti-tumor response. Clinically, it is a high-yield treatment for Metastatic Renal Cell Carcinoma (RCC) and Malignant Melanoma. 2. Why the other options are incorrect: * Etanercept: This is a TNF-alpha inhibitor (a soluble decoy receptor). It is used in autoimmune conditions like Rheumatoid Arthritis and Psoriasis, not as an anticancer agent. * Leflunomide: An inhibitor of dihydroorotate dehydrogenase (DHODH), which blocks pyrimidine synthesis. It is a Disease-Modifying Antirheumatic Drug (DMARD) used primarily in Rheumatoid Arthritis. * Thalidomide: While used in Multiple Myeloma, its mechanism involves anti-angiogenesis and TNF-alpha inhibition, not the direct activation of NK cells for RCC [2]. 3. Clinical Pearls for NEET-PG: * Capillary Leak Syndrome: The most characteristic and life-threatening side effect of Aldesleukin/IL-2. It causes hypotension, edema, and multi-organ failure due to increased vascular permeability. * RCC Management: For NEET-PG, remember that while Aldesleukin is a classic answer, modern first-line treatments for RCC often involve Tyrosine Kinase Inhibitors (e.g., Sunitinib, Pazopanib) or Immune Checkpoint Inhibitors (e.g., Nivolumab) [3]. * Interferon-alpha: Another cytokine used in RCC, but its mechanism focuses more on increasing MHC expression and inhibiting viral replication/cell growth [1].

Q: Which chemotherapeutic agent is carcinogenic?

Alkylating agents. **Explanation:** **1. Why Alkylating Agents are the Correct Answer:** Alkylating agents (e.g., Cyclophosphamide, Busulfan, Melphalan) work by attaching an alkyl group to DNA, primarily at the N7 position of guanine. This causes DNA cross-linking and strand breaks. While this mechanism effectively kills rapidly dividing cancer cells, it is **non-specific**. If the damage occurs in healthy cells and is repaired incorrectly, it can lead to permanent mutations. Consequently, alkylating agents are known to be **leukemogenic** and **carcinogenic**. The most common secondary malignancy associated with their use is **Acute Myeloid Leukemia (AML)**, typically occurring years after treatment. **2. Why Other Options are Incorrect:** * **Antibiotics:** While some cytotoxic antibiotics (like Doxorubicin) can cause secondary malignancies due to topoisomerase II inhibition, as a class, they are primarily categorized by their cytotoxic/antitumor properties rather than being inherently classified as primary carcinogens in the same clinical context as alkylating agents. * **Monoclonal Antibodies:** These are targeted therapies (e.g., Rituximab, Trastuzumab) that bind to specific antigens. They do not directly damage DNA or cause mutations, thus they do not possess carcinogenic potential. **3. High-Yield Clinical Pearls for NEET-PG:** * **Cyclophosphamide:** Associated with **Hemorrhagic Cystitis** (prevented by **MESNA**) and increased risk of **Transitional Cell Carcinoma** of the bladder. * **Busulfan:** High yield for causing **Pulmonary Fibrosis** ("Busulfan Lung") and skin hyperpigmentation. * **Nitrosoureas (Lomustine/Carmustine):** Highly lipid-soluble alkylating agents used for Brain Tumors (cross the BBB). * **Secondary Malignancy:** Always suspect a secondary AML in a patient previously treated for Hodgkin’s Lymphoma with alkylating-heavy regimens (like MOPP).

Q: Alemtuzumab is an antibody against which target molecule?

CD-52. **Explanation:** **Alemtuzumab** is a recombinant DNA-derived humanized monoclonal antibody (IgG1 kappa) directed against the **CD52** antigen. CD52 is a glycoprotein expressed at high levels on the surface of nearly all B and T lymphocytes, natural killer (NK) cells, monocytes, and macrophages. When Alemtuzumab binds to CD52, it triggers antibody-dependent cellular cytotoxicity (ADCC) and complement-mediated lysis, leading to profound and long-lasting lymphopenia. **Analysis of Incorrect Options:** * **A. CD-20:** This is the target for **Rituximab**, Ofatumumab, and Obinutuzumab. These are primarily used in B-cell non-Hodgkin lymphomas and Chronic Lymphocytic Leukemia (CLL). * **B. VEGF:** Vascular Endothelial Growth Factor is targeted by **Bevacizumab**. It acts as an angiogenesis inhibitor used in colorectal, lung, and renal cancers. * **C. EGFR:** Epidermal Growth Factor Receptor is targeted by **Cetuximab** and Panitumumab (monoclonal antibodies) or Erlotinib and Gefitinib (tyrosine kinase inhibitors). **Clinical Pearls for NEET-PG:** * **Indications:** Alemtuzumab is used in the treatment of **B-cell Chronic Lymphocytic Leukemia (B-CLL)** and relapsing-remitting **Multiple Sclerosis (MS)**. * **Adverse Effects:** Due to severe lymphopenia, patients are at high risk for **opportunistic infections** (e.g., CMV reactivation, PCP pneumonia). Prophylaxis is often required. * **Mnemonic:** "Alemtu-**52**-mab" (Rhyme "two" with "52") helps remember the CD marker. * **Other CD targets to remember:** CD3 (Muromonab), CD25 (Daclizumab/Basiliximab), CD33 (Gemtuzumab).

Q: What is the drug of choice for HER2-neu positive breast cancer?

Trastuzumab. **Explanation:** **1. Why Trastuzumab is correct:** HER2 (Human Epidermal Growth Factor Receptor 2) is a proto-oncogene that, when overexpressed, leads to aggressive tumor growth. **Trastuzumab** is a recombinant DNA-derived humanized monoclonal antibody that specifically binds to the extracellular domain of the HER2 receptor. By blocking this receptor, it inhibits tumor cell proliferation and induces antibody-dependent cellular cytotoxicity (ADCC). It is the standard of care (Drug of Choice) for HER2-positive breast cancer in both adjuvant and metastatic settings. **2. Why the other options are incorrect:** * **Tamoxifen:** This is a Selective Estrogen Receptor Modulator (SERM). It is the drug of choice for **ER/PR-positive** breast cancer in **pre-menopausal** women. * **Exemestane:** This is an irreversible steroidal **Aromatase Inhibitor (AI)**. AIs are the drug of choice for **ER/PR-positive** breast cancer in **post-menopausal** women. * **Fulvestrant:** This is a Selective Estrogen Receptor Down-regulator (SERD). It is typically used as second-line therapy in metastatic ER-positive breast cancer that has progressed on other endocrine therapies. **3. High-Yield Clinical Pearls for NEET-PG:** * **Cardiotoxicity:** The most significant side effect of Trastuzumab is reversible cardiomyopathy (decrease in LVEF). Unlike Anthracyclines (Doxorubicin), it is **not** dose-dependent and usually improves upon discontinuation. * **Testing:** HER2 status is determined via **Immunohistochemistry (IHC)**. A score of 3+ is positive; 2+ is equivocal and requires **FISH (Fluorescence In Situ Hybridization)** for confirmation. * **Triple Negative Breast Cancer (TNBC):** Defined as ER, PR, and HER2-neu negative; it has the worst prognosis and is treated primarily with chemotherapy.

Q: Which of the following drugs binds to tubulin and arrests the metaphase of the cell cycle?

Vincristine. **Explanation:** **Vincristine (Option A)** is the correct answer. It belongs to the **Vinca Alkaloids** class of antineoplastic agents. These drugs act as "spindle poisons" by binding specifically to **tubulin dimers**, preventing their polymerization into microtubules. This disruption prevents the formation of the mitotic spindle, leading to **cell cycle arrest in the Metaphase (M-phase)**. **Analysis of Incorrect Options:** * **Carmustine (Option B):** A Nitrosourea (Alkylating agent) that works by cross-linking DNA strands. It is cell-cycle non-specific and is notable for its high lipid solubility, allowing it to cross the blood-brain barrier (used in brain tumors). * **Infliximab (Option C):** A monoclonal antibody against **TNF-alpha**. It is used in the treatment of autoimmune conditions like Crohn’s disease and Rheumatoid Arthritis, not as a cytotoxic microtubule inhibitor. * **Methotrexate (Option D):** An Antimetabolite that inhibits **Dihydrofolate Reductase (DHFR)**. It interferes with DNA synthesis (S-phase) by depleting tetrahydrofolate levels. **High-Yield Clinical Pearls for NEET-PG:** * **Vinca Alkaloids (Vincristine, Vinblastine):** Prevent **assembly** (polymerization) of microtubules. * **Taxanes (Paclitaxel, Docetaxel):** Prevent **disassembly** (depolymerization) of microtubules; they "freeze" the spindle. * **Dose-Limiting Toxicity:** Vincristine is notorious for **Peripheral Neuropathy** (paresthesia, foot drop) but is relatively bone marrow-sparing. In contrast, Vinblastine is known for significant **Bone Marrow Suppression** ("Blast" = Bone marrow). * **Contraindication:** Vincristine must **never** be given intrathecally, as it is fatal (causes ascending myeloencephalopathy).

Q: Sodium 2-mercaptoethanesulfonate is used as a protective agent in:

Cancer chemotherapy. **Explanation:** **Sodium 2-mercaptoethanesulfonate (MESNA)** is a sulfhydryl compound used specifically as a cytoprotective agent in cancer chemotherapy to prevent **hemorrhagic cystitis**. **Why it is the correct answer:** Chemotherapeutic agents like **Cyclophosphamide** and **Ifosfamide** (oxazaphosphorines) are metabolized into **acrolein**, a highly reactive and toxic metabolite. Acrolein accumulates in the urinary bladder, causing irritation and sloughing of the bladder mucosa, leading to gross hematuria (hemorrhagic cystitis). MESNA works by concentrating in the urine, where its free thiol (-SH) group binds to and neutralizes acrolein, forming a non-toxic stable thioether. **Why other options are incorrect:** * **Radiotherapy:** While radioprotectors like *Amifostine* (a free radical scavenger) are used to protect salivary glands and lungs, MESNA has no role in mitigating radiation damage. * **Lithotripsy:** This is a procedure to break kidney stones; it does not involve chemical toxicity requiring a thiol-based protector. * **Hepatic encephalopathy:** This condition is managed with Lactulose, Rifaximin, or Neomycin to reduce ammonia levels, not MESNA. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic:** **M**ESNA **E**mpties **S**pecific **N**oxious **A**crolein. * **Hydration:** Vigorous intravenous hydration is always used alongside MESNA to further dilute acrolein. * **Ifosfamide vs. Cyclophosphamide:** MESNA is *mandatory* with Ifosfamide (due to higher acrolein production) but used with high-dose Cyclophosphamide. * **Other Protective Agents:** * **Dexrazoxane:** Prevents Doxorubicin-induced cardiotoxicity. * **Leucovorin (Folinic acid):** "Rescue" for Methotrexate toxicity. * **Amifostine:** Prevents Cisplatin-induced nephrotoxicity.

Q: A 50-year-old lady with severe rheumatoid disease causing joint pains and functional limitation is treated with methotrexate, requiring folinic rescue therapy. What is the mechanism by which methotrexate acts?

Binding to dihydrofolate reductase. **Explanation:** **Mechanism of Action (Correct Answer: C):** Methotrexate (MTX) is a folate antimetabolite. It acts by **competitively inhibiting the enzyme Dihydrofolate Reductase (DHFR)**. Under normal conditions, DHFR reduces dihydrofolate into tetrahydrofolate (THF), which is a crucial co-factor for the synthesis of thymidylate and purine nucleotides. By binding to DHFR with an affinity 1,000 times greater than the natural substrate, MTX depletes the cellular pool of THF, leading to a "thymineless death" of rapidly dividing cells. **Analysis of Incorrect Options:** * **Option A:** MTX does not increase folic acid excretion; it interferes with its intracellular metabolism. * **Option B:** DNA binding is the mechanism of Alkylating agents (e.g., Cyclophosphamide) or Antitumor antibiotics (e.g., Doxorubicin), not antimetabolites. * **Option D:** MTX **decreases** nucleotide synthesis by inhibiting the formation of precursors required for DNA and RNA production. **High-Yield Clinical Pearls for NEET-PG:** * **Folinic Acid (Leucovorin) Rescue:** As mentioned in the stem, Leucovorin is a reduced form of folate that bypasses the DHFR block. It is used to "rescue" normal cells from MTX toxicity (e.g., bone marrow suppression, mucositis). * **Resistance:** The most common mechanism of resistance to MTX is the production of **altered DHFR** with reduced affinity for the drug or decreased polyglutamation. * **Toxicity:** Watch for **Hepatotoxicity** (cirrhosis with long-term use in RA) and **Pulmonary fibrosis**. * **Drug Interaction:** NSAIDs and Penicillins decrease the renal excretion of MTX, increasing its toxicity.

Question 1

All of the following are true about paclitaxel except?

Accepted Answer

Obtained from E. coli

Answer

Stabilizes microtubules and prevents polymerization

Answer

Used in ovarian, cervix, and breast cancer

Answer

Most commonly causes myelosuppression and alopecia

Question 2

Melphalan is used in which of the following conditions?

Accepted Answer

Multiple myeloma

Answer

Wilm's tumour

Answer

Neuroblastoma

Answer

Retinoblastoma

Question 3

Which of the following anticancer drugs is NOT given intrathecally?

Accepted Answer

Taxol

Answer

Methotrexate

Answer

5-Fluorouracil

Answer

Cyclophosphamide

Question 4

Which agent activates natural killer cells and is useful in renal cell carcinoma?

Accepted Answer

Aldesleukin

Answer

Etanercept

Answer

Leflunomide

Answer

Thalidomide

Question 5

Which chemotherapeutic agent is carcinogenic?

Accepted Answer

Alkylating agents

Answer

Antibiotics

Answer

Monoclonal antibodies

Answer

All of the above

Question 6

Alemtuzumab is an antibody against which target molecule?

Accepted Answer

CD-52

Answer

CD-20

Answer

VEGF

Answer

EGFR

Question 7

What is the drug of choice for HER2-neu positive breast cancer?

Accepted Answer

Trastuzumab

Answer

Tamoxifen

Answer

Exemestane

Answer

Fulvestrant

Question 8

Which of the following drugs binds to tubulin and arrests the metaphase of the cell cycle?

Accepted Answer

Vincristine

Answer

Carmustine

Answer

Infliximab

Answer

Methotrexate

Question 9

Sodium 2-mercaptoethanesulfonate is used as a protective agent in:

Accepted Answer

Cancer chemotherapy

Answer

Radiotherapy

Answer

Lithotripsy

Answer

Hepatic encephalopathy

Question 10

A 50-year-old lady with severe rheumatoid disease causing joint pains and functional limitation is treated with methotrexate, requiring folinic rescue therapy. What is the mechanism by which methotrexate acts?

Accepted Answer

Binding to dihydrofolate reductase

Answer

Increasing folic acid excretion

Answer

DNA binding

Answer

Increasing nucleotide synthesis

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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