Chemotherapy: osimertinib and T790M 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.

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Pharmacology · Chemotherapy: osimertinib and T790M resistance

Sample item

A 58-year-old woman with lung adenocarcinoma and an EGFR exon 19 deletion responded to gefitinib for 11 months and then progressed. Repeat biopsy shows a T790M gatekeeper mutation. Which drug is the best next choice?

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

The answer and the reasoning

C. Osimertinib

T790M is the commonest mechanism of acquired resistance to first-generation EGFR inhibitors. Osimertinib is a third-generation irreversible inhibitor active against T790M and sparing wild-type EGFR. Switching to another first-generation drug gives no benefit.

Option by option

  • A. Vemurafenib

    Vemurafenib inhibits mutant BRAF V600E, as in melanoma.

  • B. Erlotinib

    Erlotinib is a first-generation EGFR inhibitor and is also defeated by T790M.

  • C. Osimertinib (correct)

    Correct. Osimertinib inhibits EGFR with the T790M mutation.

  • D. Crizotinib

    Crizotinib targets ALK and ROS1 rearrangements, not EGFR T790M.

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 C, Osimertinib. T790M is the commonest mechanism of acquired resistance to first-generation EGFR inhibitors.

Why is "Vemurafenib" not the answer?

Vemurafenib inhibits mutant BRAF V600E, as in melanoma.

Why is "Erlotinib" not the answer?

Erlotinib is a first-generation EGFR inhibitor and is also defeated by T790M.

Why is "Crizotinib" not the answer?

Crizotinib targets ALK and ROS1 rearrangements, not EGFR T790M.

What concept does this question test?

It tests Chemotherapy: osimertinib and T790M resistance in Pharmacology. Osimertinib is a third-generation irreversible inhibitor active against T790M and sparing wild-type EGFR. Switching to another first-generation drug gives no benefit.

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: osimertinib and T790M 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.