Update on HER2 testing
-
Upload
dr-pathmanathan -
Category
Health & Medicine
-
view
2.880 -
download
2
description
Transcript of Update on HER2 testing
UPDATE ON HER-2 TESTING
PathmanathanAdjunct Professor
Monash Medical SchoolManipal Medical School
Senior Consultant Pathologist, SDMC
Introduction • For many years, breast cancer has been
considered as a unique disease and treated as a unique disease based on clinical and pathological parameters
• During the last 20 years, extended knowledge of breast cancer biology, has put some light in our understanding of breast cancer
• High throughput technologies such as expression profiling recently introduce new classifications of IBC
• Some cellular targets, such as HER2, have been identified and drugs have been designed to specifically fight them
HER2 + breast cancer represents a heterogeneous disease targeted by specific drugs and is a hallmark of
strategic treatment
HER receptors
HER2
HER1 HER3 HER4
Cell membrane
5
ErbB-2
HER2/neu Does not need ligands activation occurs through
heterodimerization with another ErbB family member or homidimerization when HER2 is overexpressed.
ErbB-2 is the preferred dimerization partner of the other 3 ErbB family members.
Heterodimers including ErbB-2 exhibit increased stability and prolonged activation HER2 is a poor prognosis factor in breast cancer
Trastuzumab: targeting HER2
Attacks HER2-positive tumours via 5 distinct mechanisms of action1. Activation of antibody-dependent cellular
cytotoxicity (ADCC)2. Prevention of the formation of p95HER2,
a truncated and very active form of HER23. Degradation of HER2 dimers4. Inhibition of cell proliferation by preventing
HER2-activated intracellular signalling5. Inhibition of HER2-regulated angiogenesis
3
Herceptin is an effective drug
For HER2 + positive patients (importance of the quality of testing
In the metastatic setting in combination with taxanes, other CT agents + / -antiaromatase (ER+)
Herceptin action◦ Potentialization of cytotoxic drugs and hormonal
treatment◦ HER2 targeting
HER-2 Positive state shortens survival
Median survival from first diagnosis:
HER2 positive 3 years
HER2 normal 6 - 7 years
Slamon DJ et al. Science 1987;235: 177-182
HER2+ is a heterogeneous disease
Up to 50% of human epidermal growth factor receptor 2 (HER2)-positive breast cancers are also oestrogen receptor (ER) positive
Evidence of crosstalk between HER2 and ER signalling pathways
Simultaneous targeting of both pathways may improve outcomes over monotherapy
Vogel et al 2001;Penault-Llorca et al 2002; Piccart-Gebhart et al 2005
Herceptin® is indicated for HER2-positive breast cancer
HER2 positivity is the criterion to select patients for Herceptin® therapy◦ strong overexpression of the HER2 protein on the
cell surface◦ HER2 gene amplification
HER2TESTING
HER2 PROTEIN OVEREXPRESSION IHC
HER2 GENE AMPLIFICATION
FISH OR CISH
Anti her2 treatment
Breast tumor
FISH or CISH
+ –
IHC
2+ 3+
0 ou 1+
ASCO, CAP Guidelines 2006
Anti her2 treatmentFISH or CISH
– +
Anti her2 treatment
Aneuploidy or ambiguous case
Tester by IHC
2+ or -3+
Anti her2 treatment
Importance of accurate testing Accurate testing is essential to identify those
patients who will benefit from Herceptin®
◦ false-negative assessment:denies patients life-extending treatment
◦ false-positive assessment: patients will not benefit from Herceptin®
Important requirements for the pathology laboratory◦ standardisation and regular validation of testing◦ quality control measures and quality assurance◦ minimum number of cases (>150 per year)◦ detailed documentation
Abnormal 2+ Abnormal 3+Normal 0 Normal 1+
ErbB-2/HER2 in Breast Cancer
Normal Normal Abnormal lowamplification
Abnormal highamplification
METHOD ADVANTAGES DISADVANTAGES
IHC Ab to detect HER2 protein expression on cell membrane
Easy, quick, cheap, most labs can do itMorphology preservedLong storage
Affected by many variablesScoring subjective
FISH Fluorescent DNA probe to detect HER2 gene amplification
Robust , less affected by pre-analytical factorsObjective scoring systemGold standard
CostlySignals fade with timePathologists need special trainingDifficult to assess areas if invasion
CISH Digoxigenin labeled DNA probe to detect HER2 gene amplication
Less affected by pre-analytical factorsQuickUses standard light microscopyStable stainingSimultaneously assess cell morphology
New technologyDifficult to interpretCEP17 not assessed simultaneously
SISH Dinitrophenol-labeled DNA probe to detect HER2 gene amplication
AutomatedSimilar to CISH
As for CISH
Published in 2007 Problem of tumour heterogeneity apparent
at that time Group consensus meeting in 2008 to
discuss this problem◦ Vetted through CAP / American College of Medical
Cytogenetics Resource Committee
ASCO / CAP guidelines
Well documented Represents subclonal diversity Incidence varies from 5 – 30 % Increases subjectivity of HER-2
interpretation by pathologist
Intratumoral heterogeneity
Definition◦ > 5 % but < 50 % of infiltrating tumour cells have
ratio higher than 2.2
HER-2 genetic heterogeneity (GH)
If 20 cells are counted and at least one cell is identified with a HER2/ CEP17 ratio of > 2.2, the specimen has GH
If 60 cells are counted, > 3 cells show a ratio of 2.2 , GH exists
These definitions based on published works, agreed by consensus
Polyploidy 17◦ In about 19.5 % of cases tested with FISH which
show an equivocal result by absolute copy number
◦ About 1.3 % of patients showing equivocal result by HER2/ CEP17 ratio
Polysomy 17 in Breast Cancer
Polysomy, PathVysion™ kit
The >2 green signals (CEP17) and 2 orange signals (HER2 genes) per nucleus indicate polysomy
Polysomy 17 on its own◦ Not associated with HER2 overexpression◦ Not associated with increased levels of HER2
mRNA on RT-PCR◦ Not associated with high grade tumours◦ Not associated with ER negativity◦ Not associated with reduced disease free survival◦ May not benefit from Herceptin therapy
MORE STUDIES NEEDED
Bempt et.al (2008) J Clin Oncol 26: 30, pp 4869- 4874
Tubbs RR, Hicks DG, Cook J, et al. Diagn Mol Pathol. 2007;16:207– 210.
Lewis JT, Ketterling RP, Halling KC, et al. Am J Clin Pathol. 2005;124:273–281.
Fujii H, Marsh C, Cairns P, Sidransky D, Gabrielson E. Cancer Res. 1996;56:1493–1497.
Miller DV, Jenkins RB, Lingle WL, et al. 2004 ASCO Annual Meeting Proceedings. J Clin Oncol. 2004;22(14S):568.
Glockner S, Buurman H, Kleeberger W, Lehmann U, Kreipe H. Lab Invest. 2002;82:1419–1426
References