Molecular Pathology - EGFR and ALK in Lung Cancer Flashcards
1
Q
Indications for EGFR mutation analysis in lung cancer
A
- Late stage/ metastatic disease requiring drug therapy
- Choice of treatment: EGFR- targeted or conventional chemotherapy
2
Q
Purpose of microdissection of tumour biopsy?
A
- Obtain tumor cell
- Ensure high percentage of tumor DNA
- More easily detect mutations
- Reduce noise from WT signals
3
Q
How to test for EGFR mutation?
Positive and negative control?
A
PCR with primers to target exon 18.19.20.21
Gel electrophoresis to ensure PCR product quality
Sequencing for exons
Positive = DNA template with wild type EGFR Negative = distilled water, DEPC
4
Q
Interpret PCR result on gel electrophoresis
- Multiple amplification band with smear from sample
- PCR bands do not align with positive control
- Negative control well has a clear band
A
- Multiple amplification band with smear from sample
» contamination with other DNA - PCR bands do not align with positive control
» EGFR not present in sample - Negative control well has a smear band
» contamination with DNA in reagents used
5
Q
Which exon is associated with TKI resistance in EGFR +ve lung cancer
A
21
6
Q
Exon 19 deletion + T790M mutation of EGFR
Treatment?
A
T970M = known resistant mutation to TKI
Use alternative drugs
7
Q
ALK analysis:
- Breakapart FISH +ve
- IHC +ve
Interpret
A
Break-apart ALK = ALK translocation
IHC +ve = high expression
Indication for ALK tyrosine kinase inhibitor
