Fish Analysis for EGFR Abnormalities
The paraffin embedded tissue sample (200 cells) is analysed using FISH and the Vysis EGFR/CEP7 Probe Kit. EGFR abnormalities including increased copy number and amplification have been correlated with the development of many solid tumours, including non-small cell lung cancer (NSCLC) which is the leading cause of cancer death worldwide. NSCLC has a 5-year survival rate of approximately 15%.
Inhibition of EGFR by agents that block its tyrosine kinase domain has been demonstrated to reduce proliferation of lung cancer cells, resulting in suppression of tumour growth. The EGFR copy number is considered to be abnormal when high polysomy or amplification is observed.(1)
*High polysomy positive: >/= 4 EGFR copies in >/= 40% of cells;
EGFR amplification positive: Ratio CEP7:EGFR >/= 2 OR >/= 15 EGFR copies in >/= 10%
of cells OR EGFR gene clusters
1. Hirsch et al., ‘EGFR FISH in NSCLC Patients Treated with Cetuximab+Chemotherapy’, J Clin Oncol, 2008, Vol 26(20): 3351-3357.
Fish Analysis for 2p23 Alk Rearrangement
Paraffin wax embedded tissue (200 cells) is analysed using FISH and the Vysis ALK (Anaplastic Lymphoma Kinase) Break Apart FISH Probe kit designed to detect chromosome 2p23 rearrangements.
Rearrangement of the ALK locus has been implicated in the development of Non-Small Cell Lung Cancer (NSCLC), lymphoma and neuroblastoma.
Fish Analysis Ros1 Rearrangements
The paraffin wax embedded tissue (200 cells) is analysed using FISH and the SureFish ROS1 Break-Apart Probe. This probe detects rearrangements of the ROS1 gene (located at chromosomal region 6q22) but not the translocation partner.
ROS1 encodes for a receptor tyrosine kinase and rearrangements of this gene results in constitutively activated downstream signalling of oncogenic pathways. Rearrangements are not common and are found in 0,6-1,8% of patients with non-small cell lung cancer (NSCLC) (1).
Samples are considered positive if more than 15% of cells showed split 5’ROS1 (Spec. Orange) and 3’ROS1 (Spec. Green) signals (typical rearranged pattern) or isolated 3’ROS1 signals (atypical rearranged pattern).
Gain is defined as a mean copy number greater than 3 fused signals in >40% of nuclei, and amplification as the presence of >15 copies of ROS1 per cell (high polysomy) or clusters, in a minimum of 15% of analyzed cells.
1. Clave S et al. ROS1 Copy number alterations are frequent in non-small cell lung cancer. Oncotarget. 2016:7(7): 8019-8028