Cancer Pharmacology and Chemotherapy Flashcards

Which statement best describes the mechanism of resistance to imatinib in chronic myeloid leukemia (CML)?

Answer: Point mutations in the BCR-ABL kinase domain, particularly T315I

The T315I gatekeeper mutation in BCR-ABL is the most common and problematic resistance mutation, conferring resistance to first- and second-generation TKIs.

A patient receiving cisplatin-based chemotherapy develops severe nausea and vomiting despite standard antiemetics. Which agent targets substance P/NK-1 receptors and is most appropriate to add?

Answer: Aprepitant

Aprepitant is a neurokinin-1 (NK-1) receptor antagonist that blocks substance P binding, effective for delayed emesis associated with highly emetogenic chemotherapy.

Which of the following describes the pharmacodynamic rationale for using leucovorin (folinic acid) in combination with 5-fluorouracil (5-FU)?

Answer: Leucovorin stabilizes the ternary complex of 5-FU with thymidylate synthase, enhancing inhibition

Leucovorin provides reduced folate that stabilizes the ternary complex between FdUMP (5-FU metabolite) and thymidylate synthase, enhancing its cytotoxic effect.

An oncology nurse practitioner is reviewing a patient on enzalutamide for metastatic castration-resistant prostate cancer. Which CNS toxicity requires patient counseling?

Answer: Seizures, which occur in approximately 1% of patients

Enzalutamide has seizurogenic potential, occurring in ~1% of patients, and patients should be counseled to avoid driving and activities requiring alertness if seizures occur.

A patient is receiving pemetrexed for mesothelioma. Which supplementation is required to reduce hematologic and GI toxicity?

Answer: Folic acid and vitamin B12 supplementation

Folic acid (daily, starting 7 days before) and vitamin B12 (IM, every 9 weeks) supplementation are required to reduce pemetrexed-related hematologic and GI toxicities.

Which of the following correctly describes the mechanism of action of CDK4/6 inhibitors such as palbociclib in hormone receptor-positive breast cancer?

Answer: Inhibit cyclin-dependent kinases 4 and 6, preventing Rb phosphorylation and halting cell cycle at G1/S checkpoint

Palbociclib inhibits CDK4/6, keeping Rb in its hypophosphorylated active state, which sequesters E2F transcription factors and blocks G1-to-S phase progression.

A patient on CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone) presents with constipation, abdominal distension, and absent bowel sounds. Which agent is most likely responsible?

Answer: Vincristine causing autonomic neuropathy and paralytic ileus

Vincristine's neurotoxicity includes autonomic dysfunction, which can manifest as paralytic ileus requiring dose reduction or schedule adjustment.