HER2 Proven Diagnostic Accuracy Now Available for Gastric Cancer

Transcription

1 PHARMACODIAGNOSTIC HER2 Proven Diagnostic Accuracy Now Available for Gastric Cancer FROM CERTAINTY COMES TRUST

2 Since September 1998, laboratories worldwide have relied on HercepTest, the first test kit developed exclusively for a specific pharmaceutical treatment Dako has more than 40 years of experience providing accurate, consistent and reliable staining results. More than 5 million patients have been tested for HER2 status using HercepTest ; your guarantee of a proven assay. Data from a new clinical trial (ToGA) has shown that HercepTest and HER2 FISH pharmdx Kit accurately identify patients with gastric cancer who may benefit from trastuzumab treatment. These breakthrough results have led to a new indication in gastric cancer for these assays. HER2 and gastric cancer Gastric cancer is the second most common cancer-related death in the world (1). The diagnosis of advanced gastric cancer is associated with poor prognosis with current available therapies (1, 2). Overexpression of HER2 is involved in gastric cancer (3). Testing for HER2 status with immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) methods has established that overexpression of HER2 or amplification of the HER2 gene is observed about as frequently in advanced gastric cancer as in breast cancer, approximately 22% (3). HER2 status has been shown to have important implications for the treatment of gastric cancer (4). The ToGA trial ToGA is a randomized, open-label, multicenter, phase III study where advanced gastric cancer patients were randomized to receive chemotherapy or chemotherapy plus trastuzumab. The results from the ToGA trial clearly indicate that use of trastuzumab in gastric cancer in combination with chemotherapy is an effective treatment which significantly improves overall survival to over 13 months (Figure 1, 2) (4). There is a clear and urgent need for better treatment of gastric cancer. HER2 is overexpressed in approximately 22% of gastric cancers. Setting the standards in HER2 testing: HercepTest continues to be the preferred choice of assay in clinical trials. HercepTest and HER2 FISH pharmdx were exclusively used in the ToGA trial for evaluating the benefit of trastuzumab treatment in HER2-positive gastric cancer patients. This is your guarantee for proven correlation between the test and clinical evidence. 20 OS (months) Probability of survival CT CT + T CT CT+T Time (months) 4. Van Cutsem E, et al. J Clin Oncol 2009; 27: 18s, (suppl; ASCO abstr LBA2409). 0 IHC3+ or FISH+ (n=584) IHC3+ and IHC2+/FISH+ (n=446) 4. Van Cutsem E, et al. J Clin Oncol 2009; 27: 18s, (suppl; ASCO abstr LBA2409). Figure 1: Efficacy results from the ToGA trial showing that the median overall survival was significantly improved with trastuzumab in combination with chemotherapy (CT + T) compared to chemotherapy alone (CT) : 13.5 vs months, respectively (p=0.0048; HR 0.74; 95% CI 0.60, 0.91). Figure 2: Efficacy results from the ToGA trial showing median overall survival (OS) for two different groups of patients after treatment with trastuzumab (T) in addition to chemotherapy (CT) or chemotherapy alone. When the primary analysis was repeated for the high HER2 expressing group, the median OS for the group of patients who had received chemotherapy plus trastuzumab increased to 16.0 months compared to 11.8 months.

3 Trastuzumab HER2 test algorithm for gastric cancer Trastuzumab is associated with a small risk of serious cardiac toxicity (5). It is therefore important to be able to reliably identify patients who would benefit the most from this treatment. The outcome of the ToGA trial has resulted in new test algorithms for HER2 testing in gastric cancer determining the HER2-positive patients who should receive trastuzumab treatment. You may already be familiar with HER2 scoring in breast cancer but there are important differences in the scoring system for gastric cancer. The suggested algorithm specifies that all cases are diagnosed using IHC as the primary method. Those cases that are scored as equivocal 2+ are then subsequently tested using the FISH technique to ensure that appropriate assessment of patients for whom trastuzumab treatment is being considered, is adhered to (Figure 3). Humanized monoclonal antibody that targets the HER2 receptor Proven to be a beneficial treatment in breast cancer with HER2 overexpression Patients with gastric cancer overexpressing HER2 may benefit from trastuzumab therapy Trastuzumab therapy is associated with a small risk of serious cardiac toxicity and reliable HER2 test results are essential for responsible patient care HercepTest and HER2 FISH pharmdx Kit were exclusively used in the ToGA trial. Specimen HER2 IHC 0 Negative 1+ Negative 2+ Equivocal 3+ Positive HER2 FISH Report to Oncologist for Trastuzumab consideration Negative Non-amplified Positive Amplified Figure 3: HER2 test algorithm for gastric cancer.

4 HER2 testing in gastric cancer is different to that of breast cancer Gastric cancer is generally more heterogeneous than breast cancer (6). It is therefore essential to find the representative tissue for scoring. In addition, membranous HER2 staining in gastric cancer is commonly incomplete, which would give a negative score in breast cancer. The incomplete HER2 membrane staining is caused by glandular formations (6). A basolateral staining is a staining without luminal staining (making the membrane appear U shaped). A lateral membrane staining is a staining without luminal and basal staining (making the membrane appear II shaped) (Figure 4). A B Scoring HercepTest in gastric cancer tissue HercepTest scoring and HER2 FISH pharmdx interpretation should only be performed by professionals experienced in interpreting IHC stains and FISH slides respectively. Table 1 describes how surgical and biopsy specimens are scored differently for gastric cancer using IHC. The criterion of at least 10% stained tumor cells is restricted to surgical specimens. For interpretation of biopsies, a cluster of at least five tumor cells is recommended (Table 1). C Figure 4: Gastric cancer. Score 3+. HercepTest stains showing complete (A), basolateral (B) and lateral (C) HER2 membrane staining. Table 1. HercepTest scoring for gastric cancer Score to report HER2 protein overexpression assessment Surgical specimen staining pattern Biopsy specimen staining pattern 0 Negative 1+ Negative 2+ Equivocal 3+ Positive No reactivity or membranous reactivity in < 10% of tumor cell Faint/barely perceptible membranous reactivity in 10% of tumor cells; cells are reactive only in part of their membrane Weak to moderate complete, basolateral or lateral membranous reactivity in 10% of tumor cells Strong complete, basolateral or lateral membranous reactivity in 10% of tumor cells No reactivity or no membranous reactivity in any tumor cell Tumor cell cluster with a faint/barely perceptible membranous reactivity irrespective of percentage of tumor cells stained Tumor cell cluster with a weak to moderate complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained Tumor cell cluster with a strong complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained Guidelines based on Hofmann M, et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopath 2008; 52:

5 Step-by-step evaluation of HercepTest stained gastric cancer specimens Evaluation of the sections stained for HER2 protein should be done at low power magnification first. The majority of positive cases will be obvious at low power magnification. For 2+ cases 10x-20x objective magnification is recommended to verify membrane staining and for 1+ cases 40x objective magnification should be used to verify membrane staining. Figure 5 has been developed as a practical tool in the scoring procedure using the microscope magnification levels as a guidance. HER2 stained biopsy/ surgical specimen Yes Specific HER2 staining No Exclude from scoring HER2 score 0 No No membrane staining (at 40x) No Yes Membrane staining of tumor cells (distinct) Exclude from scoring Intestinal metaplasia Regenerative changes (e.g. near ulceration) Basal staining Luminal staining only Cytoplasmic staining Yes Edge artifacts Membrane staining intensity and pattern of tumor cells Crush artifacts Retraction artifacts Faint/barely perceptible membrane staining (at 40x) Weak to moderate complete, basolateral or lateral membrane staining (at 10x-20x) Strong complete, basolateral or lateral membrane staining (at 2.5x-5x) HER2 score 1+* HER2 score 2+* HER2 score 3+* * Must at least be a cluster of five stained tumor cells for biopsy specimens and at least 10% stained tumor cells for surgical specimens. Figure 5: Step-by step evaluation of HercepTest TM stained gastric cancer specimens.

6 Scoring HER2 gene amplification in gastric cancer The analysis of gene amplification is to a large extent carried out analogous to the HER2 FISH guidelines for breast cancer. For the enumeration of FISH signals in gastric cancer the HER2 (Texas Red) and CEN-17 (FITC) signals (Figure 6A, 6B) should be counted in 20 nuclei in representative tumor areas. Then the HER2/CEN-17 ratio is calculated by dividing the total number of HER2 signals by the total number of CEN-17 signals and the specimen is scored according to Table 3. Dako continues to set the standard for HER2 testing with HercepTest and now also HER2 FISH pharmdx Kit for both breast and gastric cancer. Table 3. Determination of HER2 gene status from HER2/CEN-17 signal ratio Ratio of HER2 /CEN-17 signals HER2 gene status Result < 2 Non-amplified Negative 2 Amplified Positive Results at or near the cut-off ( ) should be interpreted with caution. In those cases, count an additional 40 nuclei and recalculate the ratio. Figure 6A: Non-amplified result HER2/CEN-17 ratio < 2 Gastric cancer adenocarcinoma stained with HER2 FISH pharmdx Kit Figure 6B: Amplified result HER2/CEN-17 ratio 2 Gastric cancer adenocarcinoma stained with HER2 FISH pharmdx Kit

7 Information about HER2 testing HercepTest is a semi-quantitative immunohistochemical (IHC) assay for determination of HER2 protein overexpression in human breast and gastric tissue. HER2 FISH pharmdx TM Kit is a direct fl uorescence in situ hybridization (FISH) assay designed to quantitatively determine HER2 gene amplifi cation in formalinfi xed, paraffi n-embedded (FFPE) breast cancer tissue specimens and FFPE specimens from patients with adenocarinoma of the stomach, including gastro-esophageal junction. HER2 FISH pharmdx TM Kit is indicated in adjunction to HercepTest TM in the assessment of patients for whom trastuzumab treatment is being considered. Security of complete kits HercepTest includes all the reagents required for immunohistochemical staining, including control slides representing different expression levels of the HER2 protein. HER2 FISH pharmdx Kit is a complete system providing all reagents required to perform FISH assays. For both kits, standard validated procedures are also provided and interpretation guidelines are available on demand. HercepTest Kit Components Peroxidase-Blocking Reagent Rabbit Anti-Human HER2 Protein Visualization Reagent Negative Control Reagent DAB Buffered Substrate DAB Chromogen Epitope Retrieval Solution (10x) Wash Buffer (10x) Control Slides User-Fillable Bottles (only included in SK001) Protocol HER2 FISH pharmdx Kit Components Pre-Treatment Solution (20x) Pepsin, Ready-to-Use HER2/CEN-17 Probe Mix Stringent Wash Buffer (20x) Fluorescence Mounting Medium, containing DAPI Wash Buffer (20x) Coverslip Sealant Protocol

8 Dako and HER2 testing Dako s pharmdx is all about personalised medicine. The advantages of using the Dako pharmdx HER2 product range for gastric cancer patient testing include: Standardized assays Optimal diagnostic results Reliable assay performance Proven outcomes The Dako pharmdx kits enables you to make a difference to the assessment of patient treatment and meeting a need that has eluded gastric cancer patients for so long. You can safely rely on the accuracy and quality of HercepTest and HER2 FISH pharmdx Kit for HER2 testing. From certainty comes trust. HER2-related kits HercepTest for Automated Link Platforms (50 test) HercepTest for Dako Autostainer (50 test) HercepTest for Manual Use (35 test) HER2 FISH pharmdx Kit (20 test) Code SK001 K5207 K5204 K5331 References: (1) American Cancer Society. Global Cancer Facts & Figures 2007 ( pdf < ). (2) Ohtsu, A. Chemotherapy for metastatic gastric cancer: past, present and future. J Gastroenterol 2008; 43: (3) Bang Y, Chung H, Xu J, Lordick F, Sawaki A, Lipatov O, et al. Pathological features of advanced gastric cancer (GC): Relationship to human epidermal growth factor receptor 2 (HER2) positivity in the global screening programme of the ToGA trial. J Clin Oncol 2009; 27:15s, (Abstr 4556). (4) Van Cutsem E, Kang Y, Chung H, Shen L, Sawaki A, Lordick F, et al. Efficacy results from the ToGA trial: A phase III study of trastuzumab added to standard chemotherapy (CT) in first line human epidermal growth factor receptor 2 (HER2)-positive advanced gastric cancer (GC). J Clin Oncol 2009; 27:LBA4509. (5) Hayes DF, Picard MH: Heart of darkness: The downside of trastuzumab. J Clin Oncol 2006; 21: (6) Hofmann M, Stoss O, Shi D, Büttner R, van devijer M, Kim W, et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopath 2008; 52: pharmacodiagnostic and pharmdx are registered trademarks of Dako A/S. HercepTest is a registered trademark of Genentech, Inc., subject to licenses held by Dako. Corporate Headquarters Denmark Distributors in more than 60 countries Australia Austria Belgium +32 (0) Brazil Canada China Denmark Finland France Germany Ireland Italy Japan The Netherlands Norway Poland Spain Sweden Switzerland United Kingdom +44 (0) United States of America MAY10