Technical Notes

CML Quest (IRMA)

(BCR/abl with Imatinib Resistance Mutation Analysis)

Drug resistance develops as a result of point mutations in ATP-binding region (Kinase domain) at position 315 of the Abl gene of Ph Chromosome. This results in:

• Reactivation of signal transduction
• Formation of Hydrogen bond with the drug due to single amino acid substitution in a threonine residue of the Abl kinase domain
• Development of Imatinib resistance as a result of substitution of threonine with isoleucine Point mutations play an important role in governing resistance to imatinib w.r.t amino acids at position 315 and 253 those are critical for efficient imatinib binding. About 60% of CML patients with mutation in the Kinase domain have shown involvement of amino acids at position 255 & 351 at the point of relapse.

RT-PCR & restriction analysis is useful in detection of these mutations.
CML Quest (IRMA) can confirm the imatinib resistance status on patient's blood specimen. The test can stratify patients on the basis of:

• Response to target therapy with higher dosage of imatinib
• Response to combination therapy with IFNa & imatinib
• Complete lack of response to imatinib but may respond to higher molecules such as Dasatinib OR Nilotinib

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Methodology:

Patients DNA would be isolated, purified and subjected to PCR amplification & restriction analysis. An additional amplification directed at GAPDH would be performed as a control for sample DNA quality.