Anticancer Drugs Practice Questions

Q: Pentostatin acts by inhibiting which enzyme?

Adenosine deaminase. **Explanation:** **Pentostatin** (2'-deoxycoformycin) is a potent transition-state analog inhibitor of the enzyme **Adenosine Deaminase (ADA)**. **Mechanism of Action:** ADA is a critical enzyme in the purine salvage pathway that converts adenosine to inosine and deoxyadenosine to deoxyinosine. By inhibiting ADA, Pentostatin leads to an intracellular accumulation of **deoxyadenosine triphosphate (dATP)**. High levels of dATP are toxic to lymphocytes because they inhibit ribonucleotide reductase, thereby depleting the deoxynucleotide pools required for DNA synthesis and repair. This leads to apoptosis, particularly in T and B cells. **Analysis of Incorrect Options:** * **A. RNA-dependent DNA polymerase:** Also known as Reverse Transcriptase, this is the target for antiretroviral drugs (like Zidovudine) used in HIV treatment, not Pentostatin. * **B. Aldolase:** This is a glycolytic enzyme. While some experimental drugs target metabolic pathways, it is not the target for any standard anticancer purine analog. * **D. Adenylyl cyclase:** This enzyme converts ATP to cyclic AMP (cAMP) and is involved in G-protein coupled receptor signaling. It is not a target for cytotoxic chemotherapy. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Pentostatin is highly effective and considered a primary treatment for **Hairy Cell Leukemia**. * **Toxicity:** The major dose-limiting toxicities are myelosuppression and nephrotoxicity. * **ADA Deficiency:** Congenital deficiency of Adenosine Deaminase leads to **Severe Combined Immunodeficiency (SCID)**, highlighting the enzyme's vital role in lymphocyte survival. * **Related Drug:** **Cladribine** is another purine analog used for Hairy Cell Leukemia; it is resistant to degradation by ADA.

Q: Which of the following is NOT used in the management of carcinoma of the prostate?

Progesterone. Carcinoma of the prostate is an androgen-dependent tumor. Therefore, the primary goal of pharmacological management is **Androgen Deprivation Therapy (ADT)**, achieved by either reducing testosterone production or blocking androgen receptors. ### **Explanation of Options:** * **Progesterone (Correct Answer):** While progestins are used in endometrial and breast cancers, they have no established therapeutic role in the management of prostate cancer. They do not effectively suppress the hypothalamic-pituitary-gonadal axis or block androgen receptors in a clinically significant way for this malignancy. * **Estrogens (Option A):** Historically, high-dose estrogens (e.g., Diethylstilbestrol) were used to treat prostate cancer. They act via negative feedback on the pituitary to decrease LH secretion, thereby reducing testicular testosterone production. However, their use has declined due to cardiovascular side effects. * **Cyproterone Acetate (Option C):** This is a steroidal anti-androgen with dual action: it blocks androgen receptors and has progestational activity that suppresses LH secretion. * **Flutamide (Option D):** This is a non-steroidal (pure) anti-androgen that competitively inhibits androgen receptors in the prostate tissue. It is frequently used alongside GnRH agonists to prevent the "testosterone flare." ### **High-Yield Clinical Pearls for NEET-PG:** * **DOC for Metastatic Prostate Cancer:** GnRH agonists (e.g., **Leuprolide**, Goserelin) or GnRH antagonists (e.g., **Degarelix**). * **Abiraterone:** A CYP17 inhibitor that blocks androgen synthesis in the testes, adrenals, and the tumor itself. * **Enzalutamide:** A potent, next-generation androgen receptor signaling inhibitor. * **Bicalutamide:** Preferred over Flutamide due to a better safety profile (less hepatotoxicity) and once-daily dosing.

Q: In the VAPD regimen used in the management of ALL, which of the following drugs is not included?

Idarubicin. The **VAPD regimen** is a standard induction chemotherapy protocol used in the management of **Acute Lymphoblastic Leukemia (ALL)**. The acronym stands for: * **V:** Vincristine * **A:** Adriamycin (Doxorubicin) * **P:** Prednisolone * **D:** L-asparaginase (or sometimes Daunorubicin) ### Why Idarubicin is the Correct Answer **Idarubicin** is an anthracycline primarily used in the treatment of **Acute Myeloid Leukemia (AML)** rather than ALL. While it is structurally related to Doxorubicin, it is not a component of the classic VAPD induction regimen for pediatric or adult ALL. ### Explanation of Incorrect Options * **Vincristine (Option A):** A vinca alkaloid that inhibits microtubule polymerization. It is a backbone of almost all ALL regimens due to its lack of bone marrow toxicity. * **Prednisolone (Option B):** A glucocorticoid that induces apoptosis in lymphoid cells. It is essential for the initial "lymphoblast clear-out." * **Doxorubicin (Option C):** Also known as Adriamycin, this anthracycline inhibits Topoisomerase II. It represents the "A" in VAPD (though Daunorubicin is often substituted, both are part of the protocol logic). ### High-Yield Clinical Pearls for NEET-PG 1. **Vincristine Side Effect:** Distinctive for **peripheral neuropathy** (foot drop, constipation/paralytic ileus) but is **bone marrow sparing**. 2. **L-asparaginase:** Often the "D" in VAPD (referring to the drug's action or specific protocols like VAPL). Its unique side effects include **acute pancreatitis** and **hypofibrinogenemia**. 3. **Anthracycline Toxicity:** Both Doxorubicin and Daunorubicin cause **dilated cardiomyopathy** (dose-dependent). **Dexrazoxane** is used to prevent this cardiotoxicity. 4. **Tumor Lysis Syndrome (TLS):** Always monitor for hyperuricemia and hyperkalemia when starting VAPD in ALL patients with high tumor burden.

Q: All are indications of methotrexate except?

Renal failure. **Explanation:** **Methotrexate (MTX)** is a folate antagonist that inhibits the enzyme **dihydrofolate reductase (DHFR)**, leading to a decrease in tetrahydrofolate levels and subsequent inhibition of DNA synthesis. **Why Renal Failure is the Correct Answer:** Renal failure is a **contraindication**, not an indication, for Methotrexate. MTX is primarily excreted unchanged by the kidneys (via glomerular filtration and active tubular secretion). In patients with renal impairment, the drug accumulates rapidly, leading to life-threatening systemic toxicity, including severe bone marrow suppression and mucosal ulcerations. Furthermore, high-dose MTX can cause crystalluria, further worsening renal function. **Analysis of Other Options:** * **Leukemia:** MTX is a cornerstone in the treatment of Acute Lymphoblastic Leukemia (ALL), used in both induction and maintenance phases, as well as for CNS prophylaxis (intrathecal). * **Breast Cancer:** It is a component of classic chemotherapy regimens like CMF (Cyclophosphamide, Methotrexate, and 5-Fluorouracil). * **Rheumatoid Arthritis:** In low weekly doses, MTX is the "gold standard" Disease-Modifying Antirheumatic Drug (DMARD) due to its anti-inflammatory and immunosuppressive properties. **High-Yield Clinical Pearls for NEET-PG:** * **Rescue Agent:** **Leucovorin (Folinic acid)** is used to "rescue" normal cells from MTX toxicity by bypassing the inhibited DHFR enzyme. * **Other Indications:** Choriocarcinoma (highly sensitive), Psoriasis, Ectopic pregnancy, and Osteosarcoma. * **Side Effects:** Nephrotoxicity, Hepatotoxicity (cirrhosis with long-term use), and Pulmonary fibrosis. * **Drug Interaction:** NSAIDs and Penicillins decrease the renal clearance of MTX, increasing its toxicity.

Q: Which anticancer drug(s) does not suppress bone marrow?

Vincristine. **Explanation:** The correct answer is **Vincristine**. **1. Why Vincristine is correct:** Vincristine is a **Vinca alkaloid** that acts as a spindle poison by binding to tubulin and inhibiting microtubule polymerization. Its unique clinical profile is characterized by **minimal bone marrow suppression** (myelosuppression). This makes it an ideal component of combination chemotherapy regimens (like MOPP or CHOP), as it can be administered alongside myelosuppressive drugs without compounding hematological toxicity. Its dose-limiting toxicity is **peripheral neuropathy** rather than leukopenia or thrombocytopenia. **2. Why the other options are incorrect:** * **5-Fluorouracil (5-FU):** An antimetabolite that inhibits thymidylate synthase. It causes significant myelosuppression, along with GI toxicity (mucositis). * **Cisplatin:** A platinum compound that causes DNA cross-linking. While its primary dose-limiting toxicity is **nephrotoxicity** and ototoxicity, it still causes moderate bone marrow suppression. * **Chlorambucil:** An alkylating agent (nitrogen mustard). Like most alkylating agents, it is highly toxic to rapidly dividing cells in the bone marrow, leading to dose-dependent myelosuppression. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Non-myelosuppressive drugs:** "**V**ery **B**ad **C**ancer **L**eaves **A**ll **S**pare" * **V**incristine (Peripheral neuropathy) * **B**leomycin (Pulmonary fibrosis) * **C**isplatin (Nephrotoxicity/Ototoxicity) * **L**-Asparaginase (Pancreatitis/Clotting issues) * **A**driamycin/Doxorubicin (Cardiotoxicity - though it *is* myelosuppressive, its cardiotoxicity is more unique) * **S**teroids * **Vincristine vs. Vinblastine:** Remember, "Vincristine **C**risps the nerves (neurotoxicity), Vinblastine **B**lasts the marrow (myelosuppression)."

Q: 5-FU is the chemotherapeutic agent of choice for all except:

Carcinoma of Pancreas. **Explanation:** 5-Fluorouracil (5-FU) is a pyrimidine analog that acts as an antimetabolite by inhibiting **thymidylate synthase**, thereby blocking DNA synthesis. While 5-FU is a cornerstone in the management of various solid tumors, it is no longer considered the "agent of choice" for pancreatic cancer. **Why Carcinoma of Pancreas is the correct answer:** Historically, 5-FU was used for pancreatic cancer, but modern oncology has shifted toward more effective regimens. Currently, **Gemcitabine** (a deoxycytidine analog) or the **FOLFIRINOX** regimen (which includes 5-FU but as part of a multi-drug approach) are preferred. For single-agent therapy, Gemcitabine has shown superior clinical benefit and survival rates compared to 5-FU alone in pancreatic malignancy. **Analysis of Incorrect Options:** * **Carcinoma of Colon:** 5-FU remains the backbone of treatment for colorectal cancer (e.g., FOLFOX or FOLFIRI regimens). It is the definitive drug of choice in this category. * **Carcinoma of Stomach:** 5-FU is a primary component of many gastric cancer protocols (like the FLOT regimen) and is highly effective in adenocarcinomas of the GI tract. * **Carcinoma of Breast:** 5-FU is a standard component of classical regimens like **CMF** (Cyclophosphamide, Methotrexate, 5-FU) and **FAC**, making it a drug of choice for breast cancer. **NEET-PG High-Yield Pearls:** * **Mechanism:** Irreversible inhibition of thymidylate synthase ("Thymidylate death"). * **Leucovorin (Folinic Acid) Interaction:** Unlike with Methotrexate (where it acts as a rescue), Leucovorin is given with 5-FU to **enhance** its toxicity by stabilizing the binding of 5-FU to thymidylate synthase. * **Side Effects:** Hand-foot syndrome (palmar-plantar erythrodysesthesia), myelosuppression, and mucositis. * **Pharmacogenetics:** Patients with **DPD (Dihydropyrimidine dehydrogenase) deficiency** are at high risk of severe, life-threatening toxicity from 5-FU.

Q: Which of the following parameters is not monitored in a patient on methotrexate therapy?

Eye examination. **Explanation:** Methotrexate (MTX) is a folate antimetabolite that inhibits the enzyme **dihydrofolate reductase (DHFR)**. While it is a cornerstone in treating malignancies and autoimmune conditions (like Rheumatoid Arthritis), it carries a significant profile of systemic toxicities. **Why Eye Examination is the Correct Answer:** Unlike drugs such as Hydroxychloroquine (which requires retinal monitoring) or Ethambutol (which causes optic neuritis), **Methotrexate does not typically cause ocular toxicity**. Therefore, routine eye examinations are not a standard part of MTX monitoring protocols. **Why other options are monitored:** * **Liver Function Tests (LFTs):** MTX is hepatotoxic. Chronic use can lead to elevated transaminases, steatosis, and eventually **hepatic fibrosis or cirrhosis**. Baseline and periodic LFTs are mandatory. * **Hemogram (CBC):** As a cytotoxic drug, MTX causes **bone marrow suppression** (myelosuppression), leading to leucopenia, thrombocytopenia, and anemia. Monitoring the CBC is critical to prevent life-threatening pancytopenia. * **Lung Function Tests:** MTX can induce **interstitial pneumonitis** (Methotrexate-induced lung injury) or pulmonary fibrosis. Patients presenting with a dry cough or dyspnea require urgent pulmonary evaluation. **High-Yield Clinical Pearls for NEET-PG:** * **Rescue Therapy:** **Leucovorin (Folinic acid)** is used to "rescue" normal cells from MTX toxicity by bypassing the inhibited DHFR enzyme. * **Nephrotoxicity:** High-dose MTX can precipitate in renal tubules; **vigorous hydration and urinary alkalinization** are required. * **Contraindication:** MTX is highly **teratogenic** (Category X) and must be avoided in pregnancy. * **Antidote for Overdose:** **Glucarpidase** (carboxypeptidase G2) can rapidly reduce toxic plasma MTX levels.

Q: Which of the following causes peripheral neuritis?

Vincristine. **Explanation:** **Vincristine** is a Vinca alkaloid that acts as a **microtubule inhibitor**. It binds to tubulin and inhibits its polymerization into microtubules, leading to mitotic arrest in the M-phase. Microtubules are not only essential for cell division but are also critical for **axonal transport** in neurons. By disrupting these microtubule tracks, Vincristine interferes with the transport of neurotransmitters and essential proteins along the long axons of peripheral nerves, leading to **dose-limiting peripheral neuropathy (neuritis)**. This typically manifests as symmetrical "glove and stocking" paresthesia, loss of deep tendon reflexes, and motor weakness. **Why other options are incorrect:** * **Methotrexate:** A folate antagonist (antimetabolite) primarily known for bone marrow suppression, mucositis, and hepatotoxicity. It can cause neurotoxicity (leukoencephalopathy) if given intrathecally, but peripheral neuritis is not its hallmark. * **Busulfan:** An alkylating agent (alkyl sulfonate) most famous for causing **pulmonary fibrosis** ("Busulfan lung") and hyperpigmentation (Addisonian-like syndrome). * **Cyclophosphamide:** An alkylating agent (nitrogen mustard) notorious for **hemorrhagic cystitis** due to the metabolite **Acrolein**. It is also highly emetogenic and causes alopecia. **High-Yield Clinical Pearls for NEET-PG:** * **Vincristine vs. Vinblastine:** Remember the mnemonic: **Vincristine** = **C**NS/Nerve toxicity (Peripheral neuropathy); **Vinblastine** = **B**last (Bone marrow suppression). * Vincristine is notably **bone marrow sparing**, making it ideal for combination regimens. * **Fatal Error:** Vincristine is for **Intravenous use ONLY**. Intrathecal administration is fatal due to ascending myeloencephalopathy. * Other anticancer drugs causing peripheral neuropathy: **Paclitaxel** (microtubule stabilizer) and **Cisplatin** (platinum compound).

Q: Which one of the following medications is most likely to be responsible for this appearance?

Doxorubicin. ***Doxorubicin*** - **Doxorubicin** (anthracycline) causes **dose-dependent cardiotoxicity** leading to **dilated cardiomyopathy** and reduced ejection fraction as shown in the image. - The mechanism involves **free radical damage** to cardiac myocytes with a cumulative dose limit of ~**550 mg/m²**; **dexrazoxane** can be used for cardioprotection. *Clarithromycin* - This **macrolide antibiotic** primarily causes **QT prolongation** and potential arrhythmias, not structural heart changes. - Does not cause **cardiomegaly** or **dilated cardiomyopathy** as seen in the image. *Dexamethasone* - This **corticosteroid** causes **Cushingoid features** including moon face, buffalo hump, and central obesity. - Cardiovascular effects include **hypertension** and **fluid retention**, but not dilated cardiomyopathy. *Efavirenz* - This **NNRTI antiretroviral** causes **CNS effects** (vivid dreams, dizziness) and **neuropsychiatric symptoms**. - Associated with **lipodystrophy** and metabolic changes, but not cardiac structural abnormalities.

Question 1

Pentostatin acts by inhibiting which enzyme?

Accepted Answer

Adenosine deaminase

Answer

RNA dependent DNA polymerase

Answer

Aldolase

Answer

Adenylyl cyclase

Question 2

Which of the following is NOT used in the management of carcinoma of the prostate?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

Cyproterone acetate

Answer

Flutamide

Question 3

In the VAPD regimen used in the management of ALL, which of the following drugs is not included?

Accepted Answer

Idarubicin

Answer

Vincristine

Answer

Prednisolone

Answer

Doxorubicin

Question 4

All are indications of methotrexate except?

Accepted Answer

Renal failure

Answer

Leukemia

Answer

Breast cancer

Answer

Rheumatoid arthritis

Question 5

Which anticancer drug(s) does not suppress bone marrow?

Accepted Answer

Vincristine

Answer

5-FU

Answer

Cisplatin

Answer

Chlorambucil

Question 6

5-FU is the chemotherapeutic agent of choice for all except:

Accepted Answer

Carcinoma of Pancreas

Answer

Carcinoma of Breast

Answer

Carcinoma of Stomach

Answer

Carcinoma of Colon

Question 7

All of the following are direct DNA interacting cytotoxic agents except?

Accepted Answer

Hydroxyurea

Answer

Melphalan

Answer

Carmustine

Answer

Ifosfamide

Question 8

Which of the following parameters is not monitored in a patient on methotrexate therapy?

Accepted Answer

Eye examination

Answer

Liver function tests

Answer

Lung function tests

Answer

Hemogram

Question 9

Which of the following causes peripheral neuritis?

Accepted Answer

Vincristine

Answer

Methotrexate

Answer

Busulfan

Answer

Cyclophosphamide

Question 10

Which one of the following medications is most likely to be responsible for this appearance?

Accepted Answer

Doxorubicin

Answer

Clarithromycin

Answer

Dexamethasone

Answer

Efavirenz

Anticancer Drugs — MCQs

Anticancer Drugs — MCQs

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