RD-1i OSNA the new generation of sentinel lymph node analysis in breast cancer www.sysmex-europe.com
RD-1i OSNA the new generation of sentinel lymph node analysis in breast cancer Sentinel node biopsy has rapidly emerged as the surgical procedure of choice for early stage, clinically node-negative breast cancer patients. Conventional intra-operative analysis of the sentinel lymph node (SLN) has, until now, been performed by frozen section or touch imprint with a rapid H&E (haematoxylin and eosin) staining. The sensitivity of these histopathological methods is low because only a small proportion of the lymph node tissue can be investigated in an intra-operative setting. As a result, there is a considerable risk of false-negative results which may only be identified by subsequent post-operative examination. OSNA (One Step Nucleic Acid Amplification) is a new and widely established diagnostic approach which, for the first time, enables analysis of the whole lymph node in an intraoperative timeframe. A final, fully informed, clinical decision can be taken with confidence, without the requirement for a second surgical procedure or a confirmatory histopathological analysis.
Clinical validation studies and results The OSNA method has been evaluated in multiple multicentric studies in different countries [1 5]. In all these studies OSNA was compared to an extensive histopathological examination. The lymph nodes were cut with a special cutter device into 4 slices of 1 or 2 mm width. Alternate slices were applied either to the OSNA assay or used for multilevel histology on permanent sections. Sections were taken from 5 levels with skip ribbons of 1, 2 or 25 μm. In summary, 2313 lymph nodes have been analysed and generated the following performance data: Concordance rate 96.5 % Sensitivity 95.6 % Specificity 96.7 % As part of the Japanese study it was demonstrated that the specificity of OSNA in pn patients (144 lymph nodes analysed) was 1 % (Table 1). OSNA n = 144 (++) (+) ( ) macro pathological examination positive micro specificity: 1 % (95 % C.I.:.935 ~.993) Table 1 Analysis of 144 lymph nodes from 6 pn patients gave a specificity of 1 % negative 144 The CK19 mrna copy number of the negative lymph nodes tested in this specificity study was considerably lower than the cut-off value for the OSNA assay. This strongly indicates that the risk of false positive results can be almost excluded (Fig. 4). Number of lymph node 9 8 7 6 5 4 3 2 1 ND 25 25 5 5 75 Results of specificity study 75 1 1 125 Fig. 4 Distribution of CK19 mrna copy number of 144 lymph nodes from 6 pn patients The results of all clinical evaluations show that CK19 mrna is an excellent molecular marker for the detection of lymph node metastases in breast cancer. In conclusion the OSNA assay can be applied as a diagnostic tool for rapid detection of metastases in sentinel node biopsy samples from breast cancer patients. It is fully IVD compliant and fully approved for diagnostic use throughout the EU. 125 15 15 175 175 2 2 225 CK19 mrna (copies/μl) cut-off value 225 25 25 275 275 3 References of publications [1] Tsujimoto M et al. (27): One-Step Nucleic Acid Amplification for Intraoperative Detection of Lymph Node Metastasis in Breast Cancer Patients. Clin Cancer Res 13(16). 487. [2] Visser M et al. (28): Intra-operative rapid diagnostic method based on CK19 mrna expression for the detection of lymph node metastases in breast cancer. Int. J. Cancer. 122.2562. [3] Schem C et al. (29): One Step Nucleic Acid Amplification a molecular method for the detection of lymph node metastases in breast cancer patients; results of the German study group. Virchows Arch. 454.23. [4] Tamaki Y et al. (29): Molecular detection of lymph node metastases in breast cancer patients: Results of a multicenter trial using one-step nucleic acid amplification assay. Clin Can Res. 15 : 2879 84. [5] Snook KL et al. (21): Multicentre evaluation of intraoperative molecular analysis of sentinel lymph nodes in breast carcinoma. Br J Surg, DOI: 1.12/bjs.7347. [6] Frère-Belda MA et al. (212): Diagnostic performance of one-step nucleic acid amplification for intraoperative sentinel node metastasis detection in breast cancer patients. Int J Cancer. 212 May 15 : 13(1) : 2377 86.
Advanced technology OSNA is an automated molecular diagnostic assay using a rapid nucleic acid amplification technology (RT-LAMP*) for the detection of Cytokeratin 19 (CK19) mrna expression. CK19 is an epithelial cell marker and normally not present in lymph node tissue. In a second step the seven most promising candidate markers with high mrna expression in metastasis positive lymph nodes and minimal expression in negative lymph nodes were further evaluated in a larger number of lymph nodes (Fig. 2). The amount of CK19 mrna expression correlates with the size of metastatic foci: The system indicates the extent of the metastatic tumour burden. The basis for the evaluation of the patient result is by comparison to a standard curve with three different calibrators. Marker selection During the development of the OSNA method, Sysmex selected 45 candidate mrna markers from a public human gene expression data base. Selection criteria were a high expression level of mrna in tissues of the mammary gland in combination with minimal or no expression in normal lymph node tissue. The expression ratio of these mrna markers was evaluated using histopathologically positive and negative lymph nodes (Fig. 1 a+b). Test of 45 potential marker genes As a result CK19 mrna was identified as the most appropriate marker, showing high expression levels in metastatic lymph nodes and low expression levels in non-metastatic lymph nodes, thereby offering the potential for high sensitivity and the capability to discriminate metastatic from non-metastatic lymph nodes. + + + + + + + CK19 FOXA1 SPDEF CEA MGB1 TACSTD2 MUC1 FOXA1 (forkhead box A1), SPDEF (SAM pointed domain containing ETS transcription factor), CEA (carcinoembryonic antigen), TACSTD2 (tumor associated calcium signal transducer 2), MGB1 (mammaglobin1), MUC1 (mucin1) Fig. 2 Expression of mrna markers in histopathologically positive and negative lymph nodes Fig. 1a Ratio of mrna expressions between histopathologically positive and negative lymph nodes Fig. 1b Expression of each mrna marker in histopathologically positive lymph nodes * RT-LAMP = Reverse transcriptase loop-mediated isothermal amplification; licensed under the agreement with Eiken Chemical CO., LTD
RT-LAMP technology The innovative amplification technology RT-LAMP is a rapid isothermal procedure offering several advantages in comparison to conventional PCR methods. The amplification reaction takes place within 16 min and no prior RNA purification is necessary. Conditions for sample preparation and the special primer design are tailored to ensure high specificity and to avoid false positive results. The process is monitored in real-time in the RD-1i automated amplification and detection system. Results are available in about 3 45 minutes depending on the number of SLN analysed (Fig. 3). Six different primers are used in RT-LAMP specifically designed to avoid the amplification of CK19 pseudogenes or their transcripts, and furthermore to speed up the reaction of the assay. LAMP Primer Undesired amplification of genomic DNA is avoided by precipitation of DNA at low ph (3.5) during sample preparation and the isothermal reaction temperature at 65 C. Fig. 3 Real-time monitoring of the reaction All reagents are ready for use. 5 B1 B2 3 Target RNA Blue dyes or radioisotope colloids used for the identification of the SLN do not interfere with the OSNA reaction. 3 5 cdna F2 F1 n Isothermal procedure at 65 C n High speed reaction (16 min) n No RNA purification necessary L1 3 5 L2 n No undesired amplification of pseudogenes and genomic DNA F1: Forward Primer 1 F2: Forward Primer 2 B1: Backward Primer 1 B2: Backward Primer 2 L1: Loop Primer 1 L2: Loop Primer 2 or : DNA domain or : complementary domain n High specificity due to 6 primers
Technical specifications Instrument Method Parameter Technology Detection Gene Amplification Detector System RD-1i OSNA (One Step Nucleic Acid Amplification) CK19 mrna RT-LAMP (Reverse transcriptase loop-mediated isothermal amplification) change of transmitted light caused by the precipitation of magnesium pyrophosphate depending on the grade of the reaction Displayed parameters CK19 Q (CK19 Qualitative Result) CK19 (CK19 Risetime) CK19 C (CK19 mrna-concentration) Throughput Tissue range per sample Sample volume Reagents 4 samples per batch 5 6 mg 2 μl homogenising reagent LYNORHAG amplification reagent LYNOAMP BC all reagents are ready for use Data storage Quality control 2 samples positive and negative control 18 data points per file Interfaces host computer connection (RS232, LAN) printer connection (USB) Weight Dimensions (W x H x D) approx. 66 kg 596 x 548 x 622 mm SNCS optional with Sysmex Service Agent and remote access Design and specifications may be subject to change due to further product development. Changes are confirmed by their appearance on a newer document and verification according to its date of issue. Copyright 215 Sysmex Europe GmbH Distributor: Sysmex UK Ltd. Sysmex House, Garamonde Drive, Wymbush, Milton Keynes, MK8 8DF, United Kingdom Phone +44 87 92921 Fax +44 87 929211 info@sysmex.co.uk www.sysmex.co.uk Authorised representative: Sysmex Europe GmbH Bornbarch 1, 22848 Norderstedt, Germany Phone +49 4 52726- Fax +49 4 52726-1 lifescience@sysmex-europe.com www.sysmex-europe.com Manufacturer: Sysmex Corporation 1-5-1 Wakinohama-Kaigandori, Chuo-ku, Kobe 651-73, Japan Phone +81 78 265-5 Fax +81 78 265-524 www.sysmex.co.jp You will find your local Sysmex representative s address under www.sysmex-europe.com/contacts ZE293.EN.C.6/15