Anticancer Drugs Practice Questions

Q: Which antibiotic does not act on tubulin?

Bleomycin. The correct answer is **Bleomycin**. The question tests the knowledge of drugs that interact with microtubules (tubulin) versus those that interact directly with DNA. 1. Why Bleomycin is the correct answer: Bleomycin is a cytotoxic antibiotic that acts by binding to DNA and chelating metal ions (iron). This leads to the formation of free radicals (superoxide and hydroxyl radicals), which cause **single and double-strand DNA breaks**, ultimately inhibiting DNA synthesis. It does **not** interact with tubulin or the mitotic spindle [1]. 2. Why the other options are incorrect: * **Colchicine:** An anti-inflammatory drug used in gout that inhibits **tubulin polymerization**, preventing the formation of microtubules. * **Paclitaxel:** A taxane that acts by **stabilizing microtubules** (inhibiting depolymerization), leading to "frozen" spindles and mitotic arrest in the M-phase. * **Vincristine:** A Vinca alkaloid that binds to tubulin and **inhibits polymerization**, preventing spindle formation and causing metaphase arrest. **High-Yield 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." * **Cell Cycle Specificity:** Bleomycin acts specifically in the **G2 phase** [1], whereas microtubule inhibitors (Taxanes and Vincas) act in the **M phase**. * **Griseofulvin:** Another important antimicrobial (antifungal) that acts on tubulin, often tested alongside these options.

Q: Vacuolar degeneration and myofibrillar loss of cardiac muscle is caused by:

Doxorubicin. ### Explanation **Correct Option: D. Doxorubicin** Doxorubicin (an Anthracycline) causes cardiotoxicity through the generation of **iron-dependent free radicals** (reactive oxygen species). These radicals cause lipid peroxidation of the myocardial cell membrane. Histopathologically, this is characterized by **vacuolar degeneration** (Sarcoplasmic reticulum swelling) and **myofibrillar loss** (loss of contractile elements). There are two types of Doxorubicin cardiotoxicity: 1. **Acute:** Transient ECG changes (arrhythmias, ST-T changes). 2. **Chronic:** Dose-dependent dilated cardiomyopathy leading to congestive heart failure (CHF). The risk increases significantly once the cumulative dose exceeds **450–550 mg/m²**. **Why other options are incorrect:** * **A. Interferon alfa:** Primarily associated with flu-like symptoms, depression, and myelosuppression; it does not typically cause myofibrillar loss. * **B. Trastuzumab:** Causes Type II cardiotoxicity. Unlike Doxorubicin, it is **not dose-dependent**, does not cause structural damage (no vacuolar degeneration), and is usually **reversible** upon discontinuation. * **C. Cyclophosphamide:** High doses (used in bone marrow transplants) can cause acute hemorrhagic cystitis or acute myocarditis/pericarditis, but it is not the classic cause of chronic myofibrillar loss. **NEET-PG High-Yield Pearls:** * **Antidote:** **Dexrazoxane** (an iron chelator) is used to prevent/reduce Doxorubicin-induced cardiotoxicity. * **Monitoring:** The most sensitive gold standard for monitoring is an **Endomyocardial biopsy**, though clinically, **Echocardiography (LVEF)** is more common. * **Liposomal Doxorubicin:** Formulated to reduce cardiotoxicity by altering drug distribution.

Q: What is the mechanism of action of tamoxifen?

Partial agonist and antagonist action on estrogen receptors. **Explanation:** **Mechanism of Action:** Tamoxifen is the prototype **Selective Estrogen Receptor Modulator (SERM)**. Its unique mechanism involves binding to estrogen receptors (ER), but its effect is tissue-specific due to the recruitment of different co-activators or co-repressors. It acts as a **competitive antagonist** in the breast (inhibiting tumor growth) but functions as a **partial agonist** in other tissues like the bone, liver, and endometrium. **Analysis of Options:** * **Option A (Incorrect):** Androgen receptor blockers (e.g., Flutamide, Bicalutamide) are used in the management of prostate cancer, not breast cancer. * **Option B (Incorrect):** 5α-reductase inhibitors (e.g., Finasteride, Dutasteride) prevent the conversion of testosterone to dihydrotestosterone (DHT) and are used for BPH and male pattern baldness. * **Option D (Incorrect):** Inhibition of FSH/LH release is the mechanism of GnRH agonists (e.g., Leuprolide) when given continuously, or GnRH antagonists (e.g., Degarelix). **High-Yield Clinical Pearls for NEET-PG:** * **Indications:** Drug of choice for ER-positive breast cancer in both pre- and post-menopausal women. It is also used for primary prevention in high-risk females. * **Side Effects (Agonist effects):** Increased risk of **endometrial carcinoma** (due to uterine stimulation) and **thromboembolism** (DVT/PE). * **Beneficial Agonist effect:** It prevents post-menopausal bone loss (decreases osteoporosis risk) and improves lipid profiles. * **Metabolism:** It is a prodrug converted to its active metabolite, **Endoxifen**, by the enzyme **CYP2D6**.

Q: Methotrexate, a medication used for rheumatologic and psoriatic diseases, can cause side effects that mimic vitamin deficiencies. Which of the following vitamin deficiencies is most closely mimicked by methotrexate usage?

Folate (B9). **Explanation:** **1. Why Folate (B9) is Correct:** Methotrexate (MTX) is a structural analogue of folic acid. Its primary mechanism of action involves the **competitive inhibition of the enzyme Dihydrofolate Reductase (DHFR)** [5]. This enzyme is responsible for converting dihydrofolate into its active form, tetrahydrofolate (THF). THF is a crucial co-factor for the synthesis of thymidylate and purines, which are essential for DNA synthesis and cell division [1]. By depleting the pool of active folate, MTX causes side effects that mirror folate deficiency, such as **megaloblastic anemia, mucositis, and myelosuppression.** [4] **2. Why Other Options are Incorrect:** * **Pyridoxine (B6):** Deficiency is commonly associated with **Isoniazid (INH)** therapy, leading to peripheral neuropathy and sideroblastic anemia. * **Biotin (B7):** Deficiency is rare but can occur with excessive consumption of raw egg whites (avidin binding). It is not related to MTX. * **Niacin (B3):** Deficiency causes Pellagra (3Ds: Dermatitis, Diarrhea, Dementia). While MTX causes skin issues, the mechanism is unrelated to Niacin metabolism. **3. Clinical Pearls for NEET-PG:** * **Leucovorin Rescue:** To mitigate MTX toxicity, **Folinic acid (Leucovorin)** is administered [3]. It bypasses the inhibited DHFR enzyme to provide a source of active reduced folate [5]. * **Monitoring:** Patients on long-term MTX (e.g., for Rheumatoid Arthritis) require regular **Complete Blood Counts (CBC)** and **Liver Function Tests (LFTs)** due to risks of bone marrow suppression and hepatic fibrosis [4]. * **Contraindication:** MTX is highly **teratogenic** (Neural Tube Defects) and is contraindicated in pregnancy [2].

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

Cyclophosphamide. **Explanation:** Anticancer drugs are broadly classified into **Cell Cycle-Specific (CCS)** agents, which act on specific phases of the cell cycle, and **Cell Cycle-Non-Specific (CCNS)** agents, which act on cells regardless of their phase (including the resting G0 phase). **Why Cyclophosphamide is the correct answer:** Cyclophosphamide is an **Alkylating Agent**. These drugs work by covalently bonding alkyl groups to DNA (specifically the N7 position of guanine), leading to DNA cross-linking and strand breakage. Because this chemical reaction can occur at any time and does not require the cell to be actively synthesizing DNA or dividing, it is classified as **Cell Cycle-Non-Specific (CCNS)**. **Why the other options are incorrect:** * **Methotrexate:** An Antimetabolite that inhibits Dihydrofolate Reductase (DHFR). It is specific to the **S-phase** (DNA synthesis). * **Paclitaxel:** A Taxane that stabilizes microtubules, preventing their disassembly. It is specific to the **M-phase** (Mitosis). * **Etoposide:** A Topoisomerase II inhibitor that causes DNA strand breaks. It is specific to the **S and G2 phases**. **High-Yield Clinical Pearls for NEET-PG:** * **CCNS Drugs:** Include Alkylating agents (Cyclophosphamide, Cisplatin), Antitumor Antibiotics (Dactinomycin, Mitomycin C), and Nitrosoureas. * **Cyclophosphamide Toxicity:** Characterized by **Hemorrhagic Cystitis** due to the metabolite **Acrolein**. This is prevented by aggressive hydration and **MESNA** (Mercaptoethane sulfonate). * **Memory Aid:** "Antimetabolites are S-phase specific; Microtubule inhibitors (Vincas/Taxanes) are M-phase specific."

Q: Side effects of cisplatin include all of the following EXCEPT:

Blindness. **Explanation:** Cisplatin is a potent platinum-based alkylating agent used for various solid tumors. While it has a significant side-effect profile, **blindness** is not a characteristic or common side effect of the drug. **Why Blindness is the Correct Answer:** Ocular toxicity with cisplatin is rare and usually limited to optic neuritis or blurred vision at extremely high doses. It does not typically cause blindness. In contrast, the other options represent the "classic" triad of cisplatin toxicities. **Analysis of Incorrect Options:** * **Nausea and Vomiting (Option A):** Cisplatin is the **most highly emetogenic** chemotherapy drug. It triggers both central and peripheral pathways, often requiring aggressive antiemetic prophylaxis (e.g., Aprepitant + Ondansetron + Dexamethasone). * **Nephrotoxicity (Option B):** This is the **dose-limiting toxicity**. It causes acute tubular necrosis. To prevent this, patients are managed with **aggressive IV hydration** and **Amifostine** (a cytoprotective free-radical scavenger). * **Ototoxicity (Option C):** Cisplatin causes high-frequency hearing loss and tinnitus due to damage to the hair cells in the cochlea. This is often irreversible and more common in children. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Cisplatin:** Remember the **"3 N's"** — **N**ephrotoxicity, **N**eurotoxicity (peripheral neuropathy), and **N**ausea/vomiting, plus **Ototoxicity**. * **Amifostine:** Specifically used to reduce cisplatin-induced nephrotoxicity. * **Electrolyte Imbalance:** Cisplatin frequently causes **hypomagnesemia** and hypokalemia due to renal tubular damage. * **Carboplatin:** A related drug that is less nephrotoxic and emetogenic but more **myelosuppressive** (causes thrombocytopenia).

Q: Ramucircumab is used in the treatment of:

Non-small cell carcinoma of lungs. **Explanation:** **Ramucircumab** is a fully human IgG1 monoclonal antibody that acts as a specific **VEGFR-2 (Vascular Endothelial Growth Factor Receptor 2) antagonist**. By binding to the extracellular domain of VEGFR-2, it prevents the binding of VEGF ligands (VEGF-A, VEGF-C, and VEGF-D), thereby inhibiting downstream signaling pathways involved in angiogenesis, tumor vascularization, and metastasis. **1. Why Option B is Correct:** Ramucircumab is FDA-approved for the treatment of metastatic **Non-Small Cell Lung Cancer (NSCLC)**, typically used in combination with Docetaxel after progression on platinum-based chemotherapy. It is also used in gastric/gastroesophageal junction adenocarcinoma, colorectal cancer, and hepatocellular carcinoma. **2. Why Other Options are Incorrect:** * **Option A (Psoriasis):** Psoriasis is treated with biologics targeting TNF-α (Infliximab), IL-17 (Secukinumab), or IL-23 (Ustekinumab). * **Option C (Ascites):** While VEGF inhibitors can sometimes reduce malignant effusions, Ramucircumab is not a standard treatment for ascites. Diuretics and paracentesis remain the mainstay. * **Option D (Severe Asthma):** This is managed with monoclonal antibodies targeting IgE (Omalizumab), IL-5 (Mepolizumab), or IL-4/IL-13 (Dupilumab). **Clinical Pearls for NEET-PG:** * **Mechanism:** Unlike Bevacizumab (which binds to the VEGF-A ligand), Ramucircumab binds directly to the **VEGFR-2 receptor**. * **Key Side Effects:** Hypertension, proteinuria, arterial thromboembolic events, and impaired wound healing (common to most VEGF inhibitors). * **High-Yield Association:** Always associate "mab" drugs ending in "-umab" with human origin and those targeting "VEGFR" with anti-angiogenesis.

Q: Which anticancer drug is known to cause cerebellar ataxia?

Cytarabine. **Explanation:** **Cytarabine (Ara-C)** is the correct answer. It is a pyrimidine analog that inhibits DNA polymerase. The occurrence of **cerebellar ataxia** (dysarthria, nystagmus, and gait instability) is a classic, dose-limiting neurotoxicity associated specifically with **high-dose Cytarabine therapy**. This occurs because the drug can cross the blood-brain barrier and cause direct damage to **Purkinje cells** in the cerebellum. Risk factors include renal impairment (due to decreased clearance of the metabolite Ara-U) and older age. **Analysis of Incorrect Options:** * **Cyclophosphamide:** An alkylating agent primarily known for **hemorrhagic cystitis** (prevented by Mesna) and bone marrow suppression. It does not typically cause cerebellar toxicity. * **Chloramphenicol:** This is an antibiotic, not a primary anticancer drug. Its hallmark toxicities are **Gray Baby Syndrome** and dose-dependent/idiosyncratic bone marrow suppression (aplastic anemia). * **Vinblastine:** A Vinca alkaloid that inhibits microtubule assembly. Its primary toxicity is **bone marrow suppression** ("Blastine blasts the marrow"), whereas its sister drug, Vincristine, is more famous for peripheral neuropathy, not cerebellar ataxia. **High-Yield Clinical Pearls for NEET-PG:** * **Cytarabine:** Remember the "3 Cs": **C**ytarabine, **C**erebellar ataxia, and **C**onjunctivitis (chemical conjunctivitis is another high-dose side effect). * **Monitoring:** Patients on high-dose Ara-C must perform daily "finger-to-nose" tests and handwriting checks to screen for early signs of ataxia. * **Drug of Choice:** Cytarabine is a cornerstone in the induction therapy of **Acute Myeloid Leukemia (AML)**.

Q: Which of the following is a proliferation signal inhibitor?

Sirolimus. **Explanation:** The correct answer is **Sirolimus (Rapamycin)**. **1. Why Sirolimus is the Proliferation Signal Inhibitor:** Sirolimus belongs to the class of drugs known as **mTOR (mammalian Target of Rapamycin) inhibitors**. Its mechanism involves binding to the intracellular protein **FKBP-12**. This complex then inhibits the mTOR enzyme, which is a critical serine-threonine kinase. mTOR is responsible for regulating the cell cycle; its inhibition blocks the response to Interleukin-2 (IL-2), thereby arresting the cell cycle in the **G1 to S phase**. Because it stops the "signal" that leads to T-cell proliferation rather than just inhibiting cytokine production, it is classified as a **Proliferation Signal Inhibitor (PSI)**. **2. Why the other options are incorrect:** * **Tacrolimus (Option A) and Cyclosporine (Option C):** These are **Calcineurin Inhibitors (CNIs)**. They work upstream of Sirolimus by inhibiting the phosphatase calcineurin. This prevents the dephosphorylation of NFAT (Nuclear Factor of Activated T-cells), which is required for the *transcription* of IL-2. They inhibit the **production** of signals, whereas Sirolimus inhibits the **response** to the signal. **3. NEET-PG High-Yield Pearls:** * **Side Effects:** Unlike CNIs, Sirolimus is **not nephrotoxic**. Its primary side effects are hyperlipidemia (hypertriglyceridemia), thrombocytopenia, and impaired wound healing. * **Clinical Use:** Sirolimus is used in organ transplantation and is also used in **drug-eluting stents** (to prevent neointimal hyperplasia/restenosis). * **Everolimus:** A closely related mTOR inhibitor with a shorter half-life. * **Mnemonic:** Sirolimus **S**pares the kidney (Non-nephrotoxic) and stops the **S**ignal (PSI).

Q: Siltuximab is used in the treatment of which condition?

Castleman disease. **Explanation:** **Siltuximab** is a chimeric monoclonal antibody that acts as an **Interleukin-6 (IL-6) antagonist**. It binds directly to soluble IL-6, preventing it from binding to its receptors. 1. **Why Option A is Correct:** **Castleman disease** (specifically Multicentric Castleman Disease or MCD) is a rare lymphoproliferative disorder characterized by the overproduction of IL-6. This cytokine excess leads to systemic inflammation, lymphadenopathy, and organ dysfunction. Siltuximab is the FDA-approved first-line therapy for patients with MCD who are HIV-negative and HHV-8-negative, as it neutralizes the driver of the disease. 2. **Why Other Options are Incorrect:** * **B. Sézary syndrome:** This is a leukemic form of cutaneous T-cell lymphoma. Treatment typically involves photopheresis, retinoids (Bexarotene), or Mogamulizumab (anti-CCR4). * **C. Ankylosing spondylitis:** This is an inflammatory arthritis treated with NSAIDs, TNF-inhibitors (Etanercept, Adalimumab), or IL-17 inhibitors (Secukinumab). * **D. Non-Hodgkin lymphoma:** Treatment usually involves the CHOP regimen and anti-CD20 antibodies like **Rituximab**. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Siltuximab binds to **IL-6**, whereas **Tocilizumab** and **Sarilumab** bind to the **IL-6 Receptor**. * **Indication:** Specifically used for **MCD** (Multicentric Castleman Disease). * **Side Effects:** Upper respiratory tract infections, pruritus, and hyperuricemia. * **IL-6 Connection:** Remember that IL-6 is also a key mediator in the pathogenesis of Rheumatoid Arthritis and the Cytokine Release Syndrome (CRS) seen in CAR-T cell therapy.

Question 1

Which antibiotic does not act on tubulin?

Accepted Answer

Bleomycin

Answer

Colchicine

Answer

Paclitaxel

Answer

Vincristine

Question 2

Vacuolar degeneration and myofibrillar loss of cardiac muscle is caused by:

Accepted Answer

Doxorubicin

Answer

Interferon alfa

Answer

Trastuzumab

Answer

Cyclophosphamide

Question 3

What is the mechanism of action of tamoxifen?

Accepted Answer

Partial agonist and antagonist action on estrogen receptors

Answer

Androgenic receptor blocking action

Answer

Inhibition of enzyme 5α-reductase

Answer

Inhibition of FSH and LH release from the pituitary

Question 4

Methotrexate, a medication used for rheumatologic and psoriatic diseases, can cause side effects that mimic vitamin deficiencies. Which of the following vitamin deficiencies is most closely mimicked by methotrexate usage?

Accepted Answer

Folate (B9)

Answer

Pyridoxine (B6)

Answer

Biotin (B7)

Answer

Niacin (B2)

Question 5

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

Accepted Answer

Cyclophosphamide

Answer

Methotrexate

Answer

Paclitaxel

Answer

Etoposide

Question 6

Side effects of cisplatin include all of the following EXCEPT:

Accepted Answer

Blindness

Answer

Nausea and vomiting

Answer

Nephrotoxicity

Answer

Ototoxicity

Question 7

Ramucircumab is used in the treatment of:

Accepted Answer

Non-small cell carcinoma of lungs

Answer

Psoriasis

Answer

Ascites

Answer

Severe asthma

Question 8

Which anticancer drug is known to cause cerebellar ataxia?

Accepted Answer

Cytarabine

Answer

Cyclophosphamide

Answer

Chloramphenicol

Answer

Vinblastine

Question 9

Which of the following is a proliferation signal inhibitor?

Accepted Answer

Sirolimus

Answer

Tacrolimus

Answer

Cyclosporine

Answer

None of the above

Question 10

Siltuximab is used in the treatment of which condition?

Accepted Answer

Castleman disease

Answer

Sézary syndrome

Answer

Ankylosing spondylitis

Answer

Non-Hodgkin lymphoma

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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