Transcript ToGA BO18255 Investigator Meeting

Epidemiologia, anatomia patologica
e storia naturale del tumore
gastrico
Beppe Viale – IEO & UNIMI
HER2-positive gastric cancer
HER2-positive gastric cancer
HER2 status & clinico-pathological
correlates
HER2 testing:
gastric cancer versus breast cancer
Tumour heterogeneity is more
common in gastric cancer
Signet ring type
No amplification
Intestinal (gland forming) type
High amplification
Intra-tumoral & intra-glandular
heterogeneity
Heterogeneous gene amplification
Tumore misto
Tumore misto
Heterogeneous gene amplification
Heterogeneous gene amplification
Gastric Biopsies (6 recommended)
Tumour cells with incomplete
(basolateral) membrane staining
ToGA trial design
Phase III, randomised, open-label, international, multicentre study
Capecitabinec or
5-FU + cisplatin
(n=290)
3807 patients screeneda
810 HER2 positive
HER2-positive
advanced GC
(n=584b)
R
Capecitabinec or
5-FU + cisplatin
+ trastuzumab
(n=294)
aScreening
algorithm different from that used in breast cancer;
patients randomised, 10 patients never received treatment; cChosen at investigator’s
discretion
b594
Overall survival by HER2 status
N
Median OS
(months)
HR
95% CI
584
11.1 vs 13.8
0.74
0.60, 0.91
IHC 0 / FISH+
61
7.2 vs 10.6
0.92
0.48, 1.76
IHC 1+ / FISH+
70
10.2 vs 8.7
1.24
0.70, 2.20
IHC 2+ / FISH+
159
10.8 vs 12.3
0.75
0.51, 1.11
IHC 3+ / FISH+
256
12.3 vs 17.9
0.58
0.41, 0.81
IHC 3+ / FISH–
15
17.7 vs 17.5
0.83
0.20, 3.38
IHC 0 or 1+ / FISH+
131
8.7 vs 10.0
1.07
0.70, 1.62
IHC 2+ / FISH+ or IHC 3+
446
11.8 vs 16.0
0.65
0.51, 0.83
Subgroup
All
Pre-planned analysis
Exploratory analysis
0.2
Favours T
0.4
0.6
1
Risk ratio
2
3
4 5
Favours no T
Interaction of treatment effect with HER2 result in exploratory analysis, p=0.0368
van Cutsem E, et al. J Clin Oncol 2009; 27:Abstract 4509.
Suggested HER2 testing algorithm
in GC/GEJ cancer
Patient tumour sample
IHC
0
+1
+3
+2
retest
FISH/SISH*
–
*cut off for FISH, SISH = HER2:CEP17 ratio ≥2
+
Eligible for trastuzumab
Overall survival by HER2 status
N
Median OS
(months)
HR
95% CI
584
11.1 vs 13.8
0.74
0.60, 0.91
IHC 0 / FISH+
61
7.2 vs 10.6
0.92
0.48, 1.76
IHC 1+ / FISH+
70
10.2 vs 8.7
1.24
0.70, 2.20
IHC 2+ / FISH+
159
10.8 vs 12.3
0.75
0.51, 1.11
IHC 3+ / FISH+
256
12.3 vs 17.9
0.58
0.41, 0.81
IHC 3+ / FISH–
15
17.7 vs 17.5
0.83
0.20, 3.38
IHC 0 or 1+ / FISH+
131
8.7 vs 10.0
1.07
0.70, 1.62
IHC 2+ / FISH+ or IHC 3+
446
11.8 vs 16.0
0.65
0.51, 0.83
Subgroup
All
Pre-planned analysis
Exploratory analysis
0.2
Favours T
0.4
0.6
1
Risk ratio
2
3
4 5
Favours no T
Interaction of treatment effect with HER2 result in exploratory analysis, p=0.0368
van Cutsem E, et al. J Clin Oncol 2009; 27:Abstract 4509.
HER2 testing in gastric cancer:
best practice
HER2 testing in gastric cancer


All stomach or GE junction tumour samples should be
accurately tested for HER2 status
HER2 status should be assessed routinely by primary
IHC1


Samples with an equivocal IHC 2+ score should be
retested using ISH to confirm HER2 positivity


Patients whose tumours score IHC 3+ are eligible for
trastuzumab
Patients whose tumours score IHC 2+/FISH+ are eligible for
trastuzumab
HER2 testing should be performed by laboratories with
demonstrated proficiency
1. Hofmann M, et al. Histopathology 2008; 52:797–805.
Tissue collection
Unresectable gastric or GE junction cancer

Surgical specimens or biopsy samples are
acceptable for HER2 testing
Initial tissue processing


Transport tissue to laboratory promptly
(within 20–30 min)
Specimen is inked, cut and fixed in the
laboratory
Tissue fixation



Poor tissue fixation is the most common source of error in
HER2 testing
Place tissue in fixative as soon as possible (within 20 min)
Duration of fixation



Surgically excised samples: 6–48 h (but at least 1 h/1 mm tissue)
Biopsy samples: no longer than 24 h (but at least 1 h/1 mm tissue)
Type of fixative




10% neutral-buffered formalin is preferred
Fresh formalin (replace formalin regularly)
Other fixatives must be validated to obtain reliable results
IHC and ISH testing can be hampered by the use of
non-formalin fixatives
IHC/ISH testing
The following assays can be utilised, provided that the modified
IHC scoring system according to Hofmann et al 20081 is strictly
adhered to:
Immunohistochemistry


HercepTest™ (Dako)
CONFIRM™ anti-HER2/neu (4B5,
Ventana)
In-situ hybridisation


HER2 FISH pharmDx™ (Dako)
INFORM™ HER2 SISH (Ventana)
Paraffin embedding



Tissue samples are dehydrated in an ethanol/
xylene series and embedded in paraffin
Prolonged incubation in molten paraffin should be
avoided as high temperatures may degrade epitope
Paraffin-embedded samples can be stored
indefinitely prior to sectioning


Use fresh paraffin
Minimum size of paraffin block should be 1 cm2 to enable
proper sectioning
Sectioning and dewaxing
Sectioning




Ideally, sections should be cut from the tissue block
immediately prior to HER2 testing
Sections must be cut from a representative area of
the tumour
Thickness of tissue sections can affect interpretation
of results; ensure sections are cut to 2–4 μm
Sections are mounted on slides and dried for 12–24
h at room temperature or 1 h at 60°C
Dewaxing

Ensure complete removal of paraffin; residual
paraffin will cause false-negative assays and
increase non-specific staining
IHC scoring criteria for gastric
cancer
IHC negative (0)
No staining or membrane staining in <10% of cells
IHC negative (1+)
Faint/barely perceptible membrane staining in
>10% of cells; cells only stained in part of membrane
IHC equivocal (2+)
• Weak to moderate complete, basolateral or lateral
membrane staining in >10% of cells
• Cohesive IHC2+ clones irrespective of size (>5 cells)
IHC positive (3+)
Images courtesy of
TARGOS
• Strong complete, basolateral or lateral membrane staining
in >10% of cells in resection specimens or
• Cohesive IHC 3+ clones irrespective of size
in biopsy samples (>5 cells)
Staining intensity &
optical illusion
IHC: sample exclusion criteria
HER2 IHC stained biopsy/surgical
specimen
Edge crushing
artefacts
Within
tumour
tissue
Exclude poorly
preserved tumour
tissue
Exclude non-specific
staining
Cytoplasmic, nuclear, only basal or
luminal portion
Within nontumour tissue
Intestinal metaplasia,
regenerative changes
(near ulcerations)
Conclusions



Trastuzumab is a novel therapeutic option for
patients with HER2-positive
advanced/metastatic gastric cancer
The accurate identification of candidate
patients to HER2-targeted therapy is a novel
task for pathologists
A reliable IHC (+ ISH) assay for HER2
overexpression should be granted to all
patients with advanced/metastastic gastric
cancer