OCC Pharmacology of Chemotherapeutic Agents 4

Question 1

A patient develops hemorrhagic cystitis after receiving ifosfamide. Which metabolite is responsible and how is it prevented?

Accepted Answer

Acrolein is the urotoxic metabolite; MESNA conjugates it in the urine to form a non-toxic thioether

Answer

Ifosfamide metabolism produces acrolein, which concentrates in urine and damages bladder epithelium; MESNA (sodium 2-mercaptoethane sulfonate) conjugates acrolein in the urinary tract to form a non-toxic compound.

Question 2

Which statement correctly describes 5-FU's mechanism when combined with leucovorin?

Accepted Answer

Leucovorin increases intracellular reduced folate pools, stabilizing the ternary complex of FdUMP-TYMS-CH2THF, prolonging thymidylate synthase inhibition

Answer

Leucovorin replenishes 5,10-methylenetetrahydrofolate (CH2THF), which stabilizes the covalent ternary complex between FdUMP and thymidylate synthase, potentiating 5-FU's antimetabolite effect.

Question 3

Cisplatin's dose-limiting toxicity is nephrotoxicity. Which pharmacological maneuver best reduces this risk?

Accepted Answer

Vigorous IV hydration with normal saline to maintain high urine flow and dilute tubular platinum concentrations

Answer

Aggressive IV saline hydration before and after cisplatin is the standard strategy to reduce tubular platinum concentrations and prevent nephrotoxicity.

Question 4

Bortezomib (Velcade) treats multiple myeloma primarily through which pharmacodynamic mechanism?

Accepted Answer

Inhibition of the 26S proteasome, preventing degradation of pro-apoptotic proteins and IκB, leading to NF-κB suppression

Answer

Bortezomib is a reversible proteasome inhibitor; blocking protein degradation causes accumulation of pro-apoptotic proteins and IκB (keeping NF-κB inactive), selectively killing myeloma cells.

Question 5

A patient with metastatic colorectal cancer is started on bevacizumab (Avastin). Which mechanism explains its anti-tumor activity?

Accepted Answer

Bevacizumab binds circulating VEGF-A, preventing it from binding to endothelial VEGF receptors and inhibiting tumor angiogenesis

Answer

Bevacizumab is a monoclonal antibody that sequesters circulating VEGF-A, preventing it from binding endothelial receptors and thereby starving tumors of new blood vessel formation.

(OCC) Oncology Chemotherapy Certification Practice Test

(OCC) Oncology Chemotherapy Certification Practice Test

OCC Pharmacology of Chemotherapeutic Agents 4