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Pharmacology

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Cancer Chemotherapy

Question
92 out of 100
 

Imatinib mode of action (DNB Dec 2011)



A Competetive inhibitor of bcr abl gene product

B P glycoprotein inhibitor

C P glycoprotein stimulator

D Competitively antagonizes the ATP binding site

Ans. D Competitively antagonizes the ATP binding site

Imatinib has inhibitory activity against ABL and its derivatives V-ABL, BCR-ABL and EVT 6-ABL. Inhibit the proliferation of my­eloid cell lines that express BCR-ABL fusion proteins. Eg: asso­ciated with CML. Also inhibit proliferation of cells dependent on KIT/PDGFR for proliferation. These include mutant KIT associ­ated with GIT tumours. ETV 6 PDGFR fusion associated with chronic myelomonocythic leukemia, FIP1 F1- PDGFR A associ­ated with hypereosinophilic Syndrome.

Users


  1. CML
  2. Chronic Myelomonocytic leukemia
  3. Hyper Eosinophilic syndrome
  4. GIST
  5. Myelo fibrosis
  6. Prostatic carcinoma
  7. Glioblastoma

Adverse effects

Early: Nausea

Delayed: Myalgias, bone marrow suppression, edema, abnor­mal LFTs

  • Treatment with SCH 66336, a farnesyl protein transferase inhibi­tor that has P-glycoprotein inhibitory action, enhanced the thera­peutic efficacy of imatinib mesilate.
  • Cells resistant to imatinib mesilate showed an overexpression of P-gp. it was reported that imatinib mesilate does not cross the blood-brain-barrier, that imatinib mesilate is a substrate of P­gp, and that this efflux transporter is an important determinant of the distribution of imatinib mesilate to the central nervous system
  • This support the notion that imatinib mesilate is a substrate of P­gp. Imatinib's mechanism has action has got nothing to do with P-glycoprotein.

Note: Other TK inhibitors:

Geftinib, Erlotinib - both block intracellular component of EGFR, used in Ca-Iung.

Cancer Chemotherapy Flashcard List

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