Target FISH

Background

The level of Minimal Residual Disease (MRD) is an important prognostic factor in hematological malignancies. The detection of MRD at any stage of therapy may have drastic implications, and impact on the clinical management of the disease. New international therapeutic protocols base treatment decisions on the level of MRD.

The need

Morphological analysis of Bone Marrow (BM) can identify residual disease involving more than 5% of BM cells and thus lacks the necessary sensitivity for early detection. In addition, it is often difficult to differentiate a small leukemia blast population from normal hematopoietic blasts. When the malignant disease is associated with a specific chromosomal rearrangement, conventional cytogenetic analysis and FISH are used to identify the MRD population. Both methods have an approximate sensitivity of 10-2, not significantly better than the sensitivity of classical morphological analysis. The quantitative accuracy of FISH depends on the frequency of blast cells and the number of cells scored, improving as more cells are scored. However, scoring a large number of cells is not practical with routine FISH.

BioView’s unique solution 

BioView’s breakthrough approach suggests that, when possible, the FISH test will focus only on cells of interest. Focusing on the correct lineage of cells means the indication will be much more specific, and the sensitivity of the assay will greatly increase.

BioView’s family of products has the unique capability of correlating between two scans of the same slide. The first scan can be performed based on the analysis and classification of cells morphology or immuno-histochemical staining, and the second scan can be performed under Fluorescent illumination for the detection of a specific signal pattern. A multi-mode analysis enables accurate detection of 1 malignant cell in 104 normal cells with very high specificity.

Conclusion

The multiple parameters analysis provides phenotypic and genotypic information on the suspected cell, thereby enhancing the specificity. The hypothesis underlying preliminary studies on combined analyses of morphology and FISH at the level of the single cell is that if the chromosomal abnormality is found in entirely differentiated cells that do not proliferate, there is a reduced risk for relapse. However, if immature, proliferating cells are found to be positive, there is a high probability for relapse.

Cancer Genetics Cytogenetics, 2002, 138, p-64

Background

To date, there are several chromosomal aberrations associated with lower response rate, progression free survival and overall survival in MM. The FISH technology can detect many of the associated abnormalities not detected by conventional cytogenetic analysis, and is therefore strongly recommended for use in MM patients.

The need

FISH determination of the genetic abnormalities in Bone Marrow and peripheral blood cells of MM patients, requires a simple, low cost sorting technique, sensitive enough to detect, often rare, plasma cells, without risk of losing relevant cells.

BioView’s unique solution 

BioView’s T-FISH approach for Multiple Myeloma analysis is to scan the MGG (May-Greenwald) stained samples, originated from peripheral blood of bone marrow, automatically detect plasma cells, and target them for FISH scanning. In doing so, this approach eliminates the need to enrich blood sample for plasma cells.

Target FISH advantages for Multiple Myeloma analysis, are:

• Higher detection rate compared to cytogenetics or routine FISH
• Determination of the lineage of the cells carrying the chromosomal aberration helps define the residual disease
• The assay can be performed in a cancer cytogenetics laboratory with minimal training
• Increased specificity of MRD in MM patients with genetic abnormalities

Conclusion

T-FISH identifies cell lineage involvement in cytogenetic abnormalities, improves detection of low-level or residual MM, and may define the coexistence of hematologic karyotypic changes in individual patients.

Experimental Hematology,  2004, 32, p-254

Cancer Genetics and Cytogenetics,  2005, 158, p- 99

Sex-mismatched and specific chromosomal aberration in BMT

Background

Chimerism testing is used for routine documentation of engraftment and post-transplant follow-up of allogeneic transplant recipients. In sex-mismatched transplants when the recipient and donor are of different gender, the proportion of female and male cells is usually determined by analysis of sex chromosome markers, most often using FISH.

The need

Preforming two separate tests entails a timely and costly procedure.

BioView’s unique solution 

BioView’s solutions enable the combination of morphology and FISH tests into one. First, a sample will be prepared and stained with a stain that is suitable for the detection of blast cells. The images and coordinates of these cells will be automatically recorded. The same slide will then be stained with FISH markers suitable for the detection of the host cells (typically XY/XX in sex-mismatched transplants, or the disease typical chromosomal rearrangements, where the donor and host are of the same gender).

The system will then examine the FISH pattern only in the identified blast cells. A host blast is indicative of relapse.  If, for example,  only 4 blast cells were identified in 5000 cells, but all of them had the disease markers, this would be a clear indication of an upcoming relapse. Studies done in Sheba Medical Center (Tel Aviv, Israel) indicate that relapses can be identified up to two months prior to being diagnosed through conventional methods, without loss of specificity.

Conclusion

The results of a study conducted on 200 patients concluded that the identification of residual recipient cells as blasts predicts imminent relapse, and patients require additional therapy,.when a minute recipient blast population was detected, immune suppression was rapidly withdrawn. Conversely, when residual recipient cells displayed mature hematopoietic morphology, patients were followed by serial testing, and hazardous, unnecessary treatment could be avoided.