Anticancer Drugs Practice Questions

Q: A patient undergoing chemotherapy develops hemorrhagic cystitis. Which of the following drugs is most commonly responsible?

Ifosfamide. ***Ifosfamide*** - Ifosfamide is an alkylating agent known to cause **hemorrhagic cystitis** due to the accumulation of its toxic metabolite, **acrolein**, in the bladder. - To prevent this complication, **mesna** (2-mercaptoethane sulfonate) is routinely administered alongside ifosfamide to neutralize acrolein. *Bleomycin* - The primary and most serious dose-limiting side effect of bleomycin is **pulmonary fibrosis**. - It is not associated with bladder toxicity or hemorrhagic cystitis, as it mainly affects the lungs and skin. *Vincristine* - Vincristine is a vinca alkaloid that commonly causes **peripheral neuropathy**, manifesting as loss of deep tendon reflexes. - It is generally **myelosparing**, meaning it does not typically cause the bone marrow suppression seen with other chemotherapeutic agents, nor does it cause cystitis. *Methotrexate* - Methotrexate is an antimetabolite primarily associated with **mucositis** and **stomatitis** due to its effect on rapidly dividing cells. - It can cause hepatotoxicity and myelosuppression, but it is not a classic cause of bladder inflammation like ifosfamide.

Q: A 65-year-old woman with breast cancer is receiving combination chemotherapy including methotrexate. To reduce toxicity, leucovorin is administered alongside methotrexate. Which of the following enzymes is bypassed by leucovorin rescue during methotrexa te therapy?

Dihydrofolate reductase. ***Dihydrofolate reductase*** - **Methotrexate** inhibits the enzyme **dihydrofolate reductase (DHFR)**, which prevents the conversion of **dihydrofolate** to its active form, **tetrahydrofolate**. - **Leucovorin** (folinic acid) acts as a derivative of tetrahydrofolate that does not require the activity of **DHFR** to provide the necessary folate pool for DNA synthesis, effectively bypassing the enzyme block. *Thymidylate synthase* - **Thymidylate synthase** is the enzyme responsible for converting **dUMP** to **dTMP**, which is a downstream target inhibited by **5-fluorouracil (5-FU)**, not methotrexate. - Providing leucovorin during **5-FU** therapy actually enhances the binding of **5-fdUMP** to thymidylate synthase, potentiating its toxicity rather than rescuing the cells. *Dihydropteroate synthase* - **Dihydropteroate synthase** is a bacterial enzyme involved in the synthesis of folate from **p-aminobenzoic acid (PABA)** and is the target of **sulfonamides**. - This enzyme is not present in humans, and its inhibition is the basis for the **antibacterial** effect of sulfa drugs, making it irrelevant to methotrexate chemotherapy. *Purine nucleoside phosphorylase* - **Purine nucleoside phosphorylase** is involved in the degradation of purine nucleosides, specifically converting **inosine** and **guanosine** to their respective bases. - Deficiency of this enzyme leads to **T-cell immunodeficiency**, but it is not a pharmacological target for methotrexate or leucovorin rescue therapies.

Q: Which of the following drug-receptor target pairings are correctly matched? 1. Trastuzumab - HER2 receptor 2. Sunitinib - HER1 (EGFR) 3. Gefitinib - HER1 (EGFR)

1 and 3 are correct. ***1 and 3 are correct*** - **Trastuzumab** is a monoclonal antibody specifically designed to bind to the extracellular domain of the **HER2 receptor** (human epidermal growth factor receptor 2), inhibiting downstream signaling in HER2-positive cancers such as breast cancer. - **Gefitinib** is a tyrosine kinase inhibitor that specifically targets the intracellular domain of **HER1 (EGFR)**, making it effective in non-small cell lung cancer with specific EGFR mutations. *Only 1 is correct* - This option is incorrect because it fails to acknowledge that **Gefitinib** is also a correctly matched pair for **HER1 (EGFR)** inhibition. - It overlooks the significant role of tyrosine kinase inhibitors in modern targeted oncology therapies. *2 and 3 are correct* - This is incorrect because **Sunitinib** does not target **HER1 (EGFR)**; rather, it is a multi-targeted receptor tyrosine kinase inhibitor predominantly targeting **VEGFR** (vascular endothelial growth factor receptor) and **PDGFR** (platelet-derived growth factor receptor). - Its primary clinical indication is for renal cell carcinoma and gastrointestinal stromal tumors, differing mechanistically from EGFR-targeted therapies. *All are correct* - This option is incorrect because the inclusion of **Sunitinib** as a **HER1 (EGFR)** inhibitor is pharmacologically inaccurate. - Sunitinib is an anti-angiogenic agent targeting growth factor receptors related to vascular proliferation rather than the EGFR family.

Q: A 42-year-old female with acute lymphoblastic leukemia is being treated with a multi-drug chemotherapy protocol. On day 3 of treatment, she develops confusion, seizures, and laboratory investigations show: serum uric acid 12 mg/dL, potassium 6.2 mEq/L, phosphate 7.8 mg/dL, calcium 6.5 mg/dL, and creatinine 2.8 mg/dL. She was given allopurinol prophylaxis before starting chemotherapy. Which agent would have been more effective in preventing this complication?

Rasburicase administered before chemotherapy initiation. ***Rasburicase administered before chemotherapy initiation*** - **Rasburicase** is a recombinant **urate oxidase** enzyme that converts existing **uric acid** into **allantoin**, which is 5-10 times more soluble and easily excreted by the kidneys. - It is significantly more effective than allopurinol for **high-risk Tumor Lysis Syndrome (TLS)** because it eliminates the current uric acid burden rather than just preventing new synthesis. *Febuxostat at higher doses* - Like allopurinol, **febuxostat** is a **xanthine oxidase inhibitor** that only prevents the formation of new uric acid and does not degrade existing levels. - It is not recommended as a replacement for rasburicase in cases or high-risk scenarios involving **acute kidney injury** and severe **hyperuricemia**. *Probenecid with increased hydration* - **Probenecid** is a **uricosuric** that increases uric acid excretion, which significantly increases the risk of **uric acid crystal precipitation** in the renal tubules during TLS. - It is contraindicated in this setting as it can exacerbate **obstructive uropathy** and worsen the patient's rising **creatinine**. *Sodium bicarbonate for urinary alkalinization* - **Urinary alkalinization** is often avoided in TLS because it promotes the precipitation of **calcium phosphate crystals** in the kidneys. - In patients with severe **hyperphosphatemia**, as seen here, alkalinization increases the risk of **metastatic calcification** and causes a further drop in **serum calcium**.

Q: Which drug is used exclusively in organ transplantation and autoimmune diseases, but not in cancers?

Cyclosporine. **Explanation:** The correct answer is **Cyclosporine**. **1. Why Cyclosporine is correct:** Cyclosporine is a **calcineurin inhibitor** that selectively inhibits T-cell activation by blocking the production of Interleukin-2 (IL-2). Unlike traditional cytotoxic drugs, it does not interfere with DNA synthesis or cause bone marrow suppression. Because it lacks direct anti-proliferative activity against malignant cells, it has **no role in cancer chemotherapy**. Its clinical utility is strictly limited to preventing graft rejection in organ transplantation and managing severe autoimmune conditions (e.g., Psoriasis, Rheumatoid Arthritis). **2. Why other options are incorrect:** * **Cyclophosphamide (Option A):** An alkylating agent used for both cancers (Lymphomas, Breast cancer) and autoimmune diseases (SLE, Wegener’s). * **Methotrexate (Option B):** A folate antagonist used in high doses for malignancies (Osteosarcoma, ALL) and in low doses for autoimmune conditions (RA, Psoriasis). * **6-Mercaptopurine (Option D):** A purine analogue primarily used in the maintenance therapy of Acute Lymphoblastic Leukemia (ALL) and also in Inflammatory Bowel Disease (IBD). **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Cyclosporine binds to **Cyclophilin**, forming a complex that inhibits Calcineurin. * **Side Effects:** "The 4 H's" — **H**ypertension, **H**irsutism, **H**yperplasia of gums (Gingival Hyperplasia), and **H**yperlipidemia. * **Dose-limiting toxicity:** Nephrotoxicity (afferent arteriolar vasoconstriction). * **Metabolism:** Metabolized by **CYP3A4**; avoid grapefruit juice as it increases drug levels. * **Tacrolimus:** Another calcineurin inhibitor (binds to FKBP-12) that is more potent than Cyclosporine but does *not* cause hirsutism or gingival hyperplasia.

Q: Tamoxifen is useful in which of the following conditions?

Estrogen receptor-positive breast carcinoma. **Explanation:** **Tamoxifen** is the prototype **Selective Estrogen Receptor Modulator (SERM)**. Its therapeutic utility depends on its tissue-specific action: it acts as an **antagonist** in the breast but as a partial **agonist** in the endometrium and bone. 1. **Why Option C is Correct:** In breast tissue, Tamoxifen competitively binds to estrogen receptors (ER), blocking the proliferative effects of endogenous estrogen. Since approximately 70% of breast cancers are hormone-dependent, Tamoxifen is the gold standard for the treatment and prophylaxis of **ER-positive breast carcinoma** in both pre- and post-menopausal women. 2. **Why Other Options are Incorrect:** * **Carcinoma of the Prostate (A):** This is an androgen-dependent malignancy. Treatment typically involves androgen deprivation therapy (e.g., GnRH agonists like Leuprolide or anti-androgens like Flutamide), not anti-estrogens. * **Carcinoma of the Ovary (B):** While some ovarian cancers express ER, Tamoxifen is not a primary treatment modality. Standard care involves platinum-based chemotherapy (e.g., Carboplatin and Paclitaxel). * **Seminoma (D):** This is a germ cell tumor of the testis. It is highly radiosensitive and chemosensitive (e.g., BEP regimen: Bleomycin, Etoposide, Cisplatin), but not responsive to SERMs. **High-Yield NEET-PG Pearls:** * **Side Effects:** Increased risk of **endometrial carcinoma** (due to agonist action on the uterus) and **thromboembolism** (DVT/PE). * **Beneficial Side Effect:** It prevents post-menopausal bone loss (agonist action on bone). * **Drug Interaction:** It is a prodrug activated by **CYP2D6**. Potent inhibitors like Fluoxetine or Paroxetine can decrease its efficacy. * **Alternative:** For post-menopausal women, **Aromatase Inhibitors** (e.g., Letrozole, Anastrozole) are often preferred over Tamoxifen.

Q: Which phase of the cell cycle is resistant to most chemotherapeutic agents that are classified as phase-specific?

G0. ### Explanation **Correct Option: A (G0 Phase)** The **G0 phase (Resting Phase)** is the period where cells are quiescent and have exited the replicative cycle. Most cell cycle-specific (CCS) chemotherapeutic agents target metabolic processes active during DNA synthesis or cell division. Since cells in G0 are not actively dividing, they lack the targets (like topoisomerase, thymidylate synthase, or mitotic spindles) that these drugs attack. This makes G0 the most resistant phase and a major cause of tumor recurrence, as these "dormant" cells can re-enter the cycle after treatment ends. **Incorrect Options:** * **B (G1 Phase):** This is the pre-synthetic phase. While less sensitive than S or M, certain drugs like **Vinblastine** or **Asparaginase** can act here. * **C (G2 Phase):** This is the post-synthetic phase where proteins for mitosis are synthesized. It is specifically targeted by **Bleomycin** and **Etoposide**. * **D (M Phase):** The Mitotic phase is the most sensitive phase for **Vinca alkaloids** (inhibit microtubule assembly) and **Taxanes** (inhibit microtubule disassembly). **NEET-PG High-Yield Pearls:** 1. **Cell Cycle Specific (CCS) Drugs:** Act on dividing cells (e.g., Antimetabolites, Vincas, Taxanes). They are **schedule-dependent** (best given in divided doses or infusions). 2. **Cell Cycle Non-Specific (CCNS) Drugs:** Act on both resting and dividing cells (e.g., Alkylating agents like Cyclophosphamide, Cisplatin). They are **dose-dependent** (bolus doses). 3. **S-Phase Specific:** Most Antimetabolites (Methotrexate, 5-FU, Cytarabine). 4. **Growth Fraction:** Tumors with a high growth fraction (more cells in cycle, fewer in G0) respond better to chemotherapy (e.g., Burkitt’s Lymphoma).

Q: Hand-foot syndrome is a known side effect of which anticancer drug?

5-fluorouracil. **Explanation:** **Hand-foot syndrome (Palmar-Plantar Erythrodysesthesia)** is a distinctive dermatological toxicity characterized by redness, swelling, pain, and sometimes blistering on the palms of the hands and soles of the feet. **Why 5-fluorouracil (5-FU) is correct:** 5-FU and its oral prodrug, **Capecitabine**, are the most common causes of Hand-foot syndrome. The mechanism involves the leakage of the drug from small capillaries in the palms and soles due to high pressure and friction in these areas. Once leaked, the drug causes direct cytotoxic damage to the surrounding tissue. It is particularly associated with **continuous infusion** of 5-FU rather than bolus doses. **Analysis of Incorrect Options:** * **A. Cisplatin:** Primarily known for its "Cs": **C**ytotoxicity (Ototoxicity), **C**alculi (Nephrotoxicity), and severe **C**hemoreceptor trigger zone stimulation (highly emetogenic). * **C. Methotrexate:** Major side effects include **mucositis**, myelosuppression, and hepatotoxicity. It is also a potent teratogen. * **D. Imatinib:** A tyrosine kinase inhibitor commonly causing **periorbital edema**, fluid retention, and GI upset. **NEET-PG High-Yield Pearls:** * **Management:** Pyridoxine (Vitamin B6) is often used for prophylaxis/treatment, along with topical emollients and dose reduction. * **Other drugs causing HFS:** Cytarabine, Doxorubicin (especially liposomal), and Sorafenib. * **5-FU Antidote:** Uridine triacetate is used for life-threatening 5-FU or Capecitabine overdose/toxicity. * **Thymidylate Synthase:** 5-FU acts by inhibiting this enzyme, leading to "thymineless death" of cells.

Q: Pulmonary fibrosis is a known side effect of which of the following medications?

Bleomycin. **Explanation:** **Bleomycin** is a cytotoxic antibiotic used in cancer chemotherapy (e.g., Hodgkin’s lymphoma, testicular cancer). Its most significant and dose-limiting toxicity is **Pulmonary Fibrosis**. The underlying mechanism involves the drug’s inability to be inactivated in the lungs. While most tissues contain "Bleomycin hydrolase," the lungs and skin lack this enzyme. This leads to the accumulation of the drug, resulting in oxidative stress, DNA damage, and subsequent fibroblast proliferation, leading to "Bleomycin-induced lung injury." **Analysis of Incorrect Options:** * **B. Cisplatin:** Primarily known for its **Nephrotoxicity** (prevented by aggressive hydration and Amifostine) and Ototoxicity. It does not typically cause pulmonary fibrosis. * **C. Methotrexate:** While it can cause an acute hypersensitivity pneumonitis, its hallmark toxicities are **Myelosuppression** (rescued by Leucovorin), Mucositis, and Hepatotoxicity. * **D. Actinomycin D:** Mainly associated with myelosuppression and "radiation recall" phenomenon; it is not a classic cause of pulmonary fibrosis. **High-Yield Clinical Pearls for NEET-PG:** * **Monitoring:** Patients on Bleomycin must be monitored with **Pulmonary Function Tests (PFTs)**, specifically looking for a decrease in **DLCO** (Diffusion Capacity of Carbon Monoxide). * **Risk Factor:** The risk of fibrosis increases significantly when the cumulative dose exceeds **400 units**. * **Other Drugs causing Pulmonary Fibrosis:** Remember the mnemonic **"B-A-M"**: **B**leomycin, **A**miodarone, **M**usulfan (Busulfan), and **M**ethotrexate (rarely). * **Skin Toxicity:** Bleomycin also causes **Flagellate hyperpigmentation** of the skin.

Question 1

A patient undergoing chemotherapy develops hemorrhagic cystitis. Which of the following drugs is most commonly responsible?

Accepted Answer

Ifosfamide

Answer

Bleomycin

Answer

Vincristine

Answer

Methotrexate

Question 2

A 65-year-old woman with breast cancer is receiving combination chemotherapy including methotrexate. To reduce toxicity, leucovorin is administered alongside methotrexate. Which of the following enzymes is bypassed by leucovorin rescue during methotrexa te therapy?

Accepted Answer

Dihydrofolate reductase

Answer

Thymidylate synthase

Answer

Dihydropteroate synthase

Answer

Purine nucleoside phosphorylase

Question 3

Which of the following drug-receptor target pairings are correctly matched? 1. Trastuzumab -
HER2 receptor 2. Sunitinib - HER1 (EGFR) 3. Gefitinib - HER1 (EGFR)

Accepted Answer

1 and 3 are correct

Answer

Only 1 is correct

Answer

2 and 3 are correct

Answer

All are correct

Question 4

A 42-year-old female with acute lymphoblastic leukemia is being treated with a multi-drug chemotherapy protocol. On day 3 of treatment, she develops confusion, seizures, and laboratory investigations show: serum uric acid 12 mg/dL, potassium 6.2 mEq/L, phosphate 7.8 mg/dL, calcium 6.5 mg/dL, and creatinine 2.8 mg/dL. She was given allopurinol prophylaxis before starting chemotherapy. Which agent would have been more effective in preventing this complication?

Accepted Answer

Rasburicase administered before chemotherapy initiation

Answer

Febuxostat at higher doses

Answer

Probenecid with increased hydration

Answer

Sodium bicarbonate for urinary alkalinization

Question 5

A pharmaceutical company develops a new checkpoint inhibitor targeting LAG-3 (Lymphocyte Activation Gene-3) for melanoma. Compared to PD-1 inhibitors, what advantage would combination therapy with both agents theoretically provide?

Accepted Answer

Dual blockade of different inhibitory pathways enhancing T-cell activation

Answer

Complete elimination of immune-related adverse events

Answer

Activation of humoral immunity instead of cellular immunity

Answer

Reduced cost of treatment due to synergistic dosing

Question 6

Which drug is used exclusively in organ transplantation and autoimmune diseases, but not in cancers?

Accepted Answer

Cyclosporine

Answer

Cyclophosphamide

Answer

Methotrexate

Answer

6-Mercaptopurine

Question 7

Tamoxifen is useful in which of the following conditions?

Accepted Answer

Estrogen receptor-positive breast carcinoma

Answer

Carcinoma of the prostate

Answer

Carcinoma of the ovary

Answer

Seminoma

Question 8

Which phase of the cell cycle is resistant to most chemotherapeutic agents that are classified as phase-specific?

Accepted Answer

G0

Answer

G1

Answer

G2

Answer

M

Question 9

Hand-foot syndrome is a known side effect of which anticancer drug?

Accepted Answer

5-fluorouracil

Answer

Cisplatin

Answer

Methotrexate

Answer

Imatinib

Question 10

Pulmonary fibrosis is a known side effect of which of the following medications?

Accepted Answer

Bleomycin

Answer

Cisplatin

Answer

Methotrexate

Answer

Actinomycin D

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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