Chemotherapy: arsenic trioxide in APL: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Chemotherapy: arsenic trioxide in APL

Sample item

Which drug used in acute promyelocytic leukaemia promotes degradation of the PML-RARA fusion protein and requires ECG monitoring because it prolongs the QT interval?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Arsenic trioxide

Arsenic trioxide binds the PML part of the fusion protein, causing its degradation and promoting differentiation and apoptosis. Like all-trans retinoic acid it can cause differentiation syndrome, and it additionally prolongs QT, so potassium and magnesium must be kept normal and the ECG followed.

Option by option

  • A. Arsenic trioxide (correct)

    Correct. Arsenic trioxide degrades PML-RARA and prolongs the QT interval.

  • B. Vincristine

    Vincristine blocks microtubule assembly and its dose-limiting toxicity is neuropathy.

  • C. Cytarabine

    Cytarabine inhibits DNA polymerase and does not target PML-RARA.

  • D. Methotrexate

    Methotrexate inhibits dihydrofolate reductase and is not used to degrade PML-RARA.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Arsenic trioxide. Arsenic trioxide binds the PML part of the fusion protein, causing its degradation and promoting differentiation and apoptosis.

Why is "Vincristine" not the answer?

Vincristine blocks microtubule assembly and its dose-limiting toxicity is neuropathy.

Why is "Cytarabine" not the answer?

Cytarabine inhibits DNA polymerase and does not target PML-RARA.

Why is "Methotrexate" not the answer?

Methotrexate inhibits dihydrofolate reductase and is not used to degrade PML-RARA.

What concept does this question test?

It tests Chemotherapy: arsenic trioxide in APL in Pharmacology. Like all-trans retinoic acid it can cause differentiation syndrome, and it additionally prolongs QT, so potassium and magnesium must be kept normal and the ECG followed.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Chemotherapy: arsenic trioxide in APL?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.