I was given the following as an example for a quiz question but i don't understand the answer. Any help will be most welcome:

Question: Iressa is a Tyrosine Kinase Inhibitor. As a young oncologe, to whome of the patients will you recommand not to take this treatment:

a. Biopsia has shown that the EGF receptor is mutant

b. Biopsia has shown that the RAS protein is mutant

c. Biopsia has shown that the MAP Kinase stays in the nucleuous permanently

d. The treatment can help each of a,b,c, cases.

The right answer should be a. Can someone see why and help here?

I know that tyrosine kinase receptor is the inside part of the EGF receptor (where the two monomeres become a dimer and phosphorelate each other). So, if the EGF receptor is mutant, shuldn't it help inhibiting it's continuation inside the cell and thus prevent to many EGF cascades?


  • $\begingroup$ Have they given more information how the receptor is mutant? $\endgroup$ – Chris Jun 11 '18 at 7:35
  • $\begingroup$ The right answer should be A? Patients with EGFR-positive lung cancer who are also positive for mutant K-Ras don't respond to erlotinib, a common EGFR-TKI (example). This is directly because the bulk of Ras mutations are activating, which would naturally subvert the need for EGFR-RTK signaling to begin with. Thus, for mutant Ras patients I wouldn't recommend TKIs. $\endgroup$ – CKM Jun 11 '18 at 14:16

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