Jennie Bell
CMGS/ACC Spring meeting
14th April 2010
 Cancer
cells acquire the capacity for autonomous
and dysregulated proliferation
• Uncontrolled production of growth factors
• Enhanced expression of growth factor receptors
↳Proliferation of cancer cells
↳Induction of angiogenesis
↳Metastasis
Lung cancer cell
EGFR
KRAS
C-KIT
EGFR is a transmembrane
receptor belonging to a
family of 4 related proteins
 The majority of human
epithelial cancers are marked
by activation of growth
factors and receptors of the
epidermal growth factor
receptor family





KRAS is a gene in the EGFR
signaling pathway
Activating mutations impair
GTPase activity resulting in
constitutive activation
Up to 30% of all human
tumours contain a KRAS
mutation
Most commonly observed in
lung, colon and pancreatic
cancer and haematopoietic
neoplasm
http://www.kras-info.com/
 c-KIT
is a proto-oncogene and a
transmembrane receptor
 Ligand binding activates
intracellular tyrosine kinase
domain
 PDGFRa is homologous to KIT
and functions in a parallel
pathway.
 Both genes can be mutated in
GIST Gastrointestinal stromal tumours.
 EGFR
was the first growth factor receptor proposed
as a target for cancer therapy.
 Development
of EGFR antagonists for treatment of
metastatic epithelial cancers:
• Non-small-cell lung cancer (NSCLC)
• Squamous cell carcinoma of head and neck
• Colorectal cancer
• Pancreatic cancer
EGFR inhibitors approved
for cancer treatment:
Erlotinib
Gefitinib
Cetuximab
Panitumumab
 Gefitinib, a
small molecule tyrosine kinase inhibitor,
is a targeted therapy for the treatment of patients
with non-small cell lung cancer
 The
drug binds to the EGFR TK domain with high
specificity and affinity resulting in highly effective
inhibition of the aberrant signalling pathways.
 Imatinib
is a synthetic tyrosine kinase inhibitor
(Glivec, Novartis Pharmaceuticals UK) successfully used in
the treatment of CML
 Imatinib
can block the activated receptor tyrosine
kinase activity of c-kit
 Targeted
therapeutic approach in GIST.
 Not
all patients respond in the same way to drug
treatment
 The presence or absence of a mutation can influence
response
 The presence of different somatic mutations within
each gene can affect the action of the drug at the
cellular level

Clinical trials have shown that patients with certain EGFR
mutations derive significant benefit from gefitinib treatment
while patients without these mutations gain more benefit from
standard chemotherapy

Mutations are found in four exons of the EGFR gene (exons
18 to 21).

Deletions in exon 19 and a point mutation in exon 21
(L858R) account for around 90% of all activating mutations
 As
Gefitinib has been shown to benefit patients with
particular somatic sequence changes
 Essential
to identify specific sequence changes in
individual patients
 Match
sequence variants with specific patient
treatment
 GIST
patients with a somatic mutation generally
have a higher response to treatment than those that
do not.

Exon 11 most commonly mutated in (67% of cases)
• Mutations in exon 11 generally respond to treatment with Imatinib better than mutations
in other exons.

Exon 9 mutations are less common (17% of cases)
• Exon 9 mutations have a lower response rate to Imatinib therapy vs exon 11 mutations
(but a better response rate to Imatinib than c-kit "wild-type" GIST)
 There
has been a recent paradigm shift in cancer
patient treatment
Broad-spectrum cytotoxic therapy
 The
molecular targeted treatment
presence of a sequence variant within one of
these genes (EGFR, c-Kit, KRAS) can determine a
patient’s treatment.
A
patient presents with lung cancer
 A biopsy is taken
 A diagnosis of NSCLC should be confirmed by a
Consultant Histopathologist
 Subsequent molecular analysis of the tumour sample
is required
 Identifying patients with an EGFR mutation is a critical
part of the patient care pathway
 Appropriate treatment discussion with patient
Brendan O’Sullivan/Frances Hughes
BMS, UHB
Jennie Bell/Dr Fiona Macdonald
Consultant Clinical Scientists, BWH
http://www.egfr-info.com/EGFR-exon
Dr Philippe Tanière
Consultant Histopathologist
UHB
West Midlands Regional Genetics
BWH
Department of Cellular Pathology
UHB
 Partnership
established in 2002
 Department
of Cellular Pathology, University
Hospital Birmingham and West Midlands Regional
Genetics Laboratory
 Tumour
studies in colon cancer (MSI and IHC in
Lynch syndrome/HNPCC)
 KIT
and PDGFRa analysis for GIST
• Sequencing exons 9, 11, 13, 17 c-kit and exons 10, 12, 14, 18 PDGFRa
 KRAS
analysis for lung and colon cancer
• Pyrosequencing exon 2 KRAS
 EGFR
for lung cancer
• Analysis of exons 18 to 21 (RQ-PCR, sequencing)
 All
molecular work is performed within the
Regional Genetics Laboratory
A
basic report is issued giving details of any
sequence variants identified (or not)
 The
results are integrated into an overall patient
summary by Consultant Histopathologist
160
152
140
122
No. of Reports
120
100
80
64
60
38
40
20
0
2007
2008
2009
2010*
Year
* Samples reported 1st Jan to 31st March 2010
250
219
194
No. of Reports
200
150
100
50
0
Validation
0
2008
2009
Year
2010*
* Samples reported 1st Jan to 31st March 2010
 Service
validation complete
 Problem with availability of DxS kit
 Currently using direct sequencing
 Reports will be issued from 1st April 2010
 BRAF
analysis in colorectal cancer
• Pyrosequencing based assay
 BRAF
and KIT in melanoma
• KIT mutated in non-skin melanomas
• BRAF mutated in sun exposed areas
 MGMT
methylation in gliomas and endocrine tumours
• predictive to alkylant based chemotherapy
 ERCC1
expression
• RNA based test on paraffin sections
• Predictive marker to response to platinum based chemotherapy (lung, pancreas, stomach
and colon)
 Management
of results for patients referred with cancer is
co-ordinated by Consultant Histopathologist
 Equipment
and molecular expertise is provided by the
Genetics Service
 Molecular
testing is performed to accredited standards
 More
drug targets
 Improved
drug treatments
 Further
expansion of molecular pathology services is
anticipated
 Supported
by strong cross-discipline collaboration
 Molecular
Laboratory Staff
 Dr Fiona Macdonald
 Brendan
O’Sullivan
 Frances Hughes
 Dr Philippe Tanière
jenny.bell@bwhct.nhs.uk
phillipe.taniere@uhb.nhs.uk