Chemotherapy: P-glycoprotein multidrug resistance: 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.

Try it

Pharmacology · Chemotherapy: P-glycoprotein multidrug resistance

Sample item

A lymphoma that responded to doxorubicin relapses and is now resistant to doxorubicin, vincristine and paclitaxel, drugs with different structures and targets. Which mechanism best explains this pattern?

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

The answer and the reasoning

A. Overexpression of the P-glycoprotein efflux pump

Multidrug resistance occurs when the MDR1 gene product P-glycoprotein pumps natural-product drugs such as anthracyclines, vinca alkaloids, taxanes and etoposide out of the cell. Cross-resistance to structurally unrelated drugs is the clue. Antimetabolite resistance usually involves target-enzyme changes.

Option by option

  • A. Overexpression of the P-glycoprotein efflux pump (correct)

    Correct. P-glycoprotein effluxes anthracyclines, vinca alkaloids and taxanes together.

  • B. Increased expression of thymidylate synthase

    Increased thymidylate synthase causes resistance to fluorouracil.

  • C. Higher activity of the DNA repair enzyme MGMT

    Higher MGMT activity causes resistance to alkylating agents such as temozolomide and nitrosoureas.

  • D. Amplification of the dihydrofolate reductase gene

    DHFR amplification causes resistance to methotrexate and not to this group of drugs.

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.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Overexpression of the P-glycoprotein efflux pump. Multidrug resistance occurs when the MDR1 gene product P-glycoprotein pumps natural-product drugs such as anthracyclines, vinca alkaloids, taxanes and etoposide out of the cell.

Why is "Increased expression of thymidylate synthase" not the answer?

Increased thymidylate synthase causes resistance to fluorouracil.

Why is "Higher activity of the DNA repair enzyme MGMT" not the answer?

Higher MGMT activity causes resistance to alkylating agents such as temozolomide and nitrosoureas.

Why is "Amplification of the dihydrofolate reductase gene" not the answer?

DHFR amplification causes resistance to methotrexate and not to this group of drugs.

What concept does this question test?

It tests Chemotherapy: P-glycoprotein multidrug resistance in Pharmacology. Cross-resistance to structurally unrelated drugs is the clue. Antimetabolite resistance usually involves target-enzyme changes.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: P-glycoprotein multidrug resistance?

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.