ROS1 status in non-small-cell lung cancer (NSCLC) is determine using a validated ROS1 IHC test as a first screening method. Patient samples that show ROS1 IHC overexpression in the tumour cells are subsequently subjected to ROS1 FISH analysis for confirmation of a positive ROS1 status.
ROS1 IHC testing is performed using the Cell Signalling Technology anti-ROS1 (D4D6) Rabbit monoclonal primary antibody used in combination with the OptiView DAB IHC Detection kit and OptiView Amplification Kit as a fully automated immunohistochemistry assay on the Ventana BenchMark Ultra automated slide stainer.
ROS1 FISH testing is performed using the Vysis 6q22 ROS1 Break apart FISH probe (Abbott, RUO).
Acceptable specimens for the assay are formalin (10% buffered or Zinc formalin)-fixed (6-48 hours), paraffin-embedded NSCLC tissue specimens. Sectioned slides must be analysed within 3 months after sectioning date.
One representative paraffin block is preferred. Alternatively, 5 unstained freshly sectioned tissue sections are accepted (1 slide of 4 or 5 µm thickness for H&E staining, a minimum of 2 slides of 4-5 µm thickness for ROS1 IHC testing and a minimum of 2 slides of 3 µm thickness for ROS1 FISH testing).
Maintain and ship specimens at ambient temperature.
Fixatives other than buffered formalin, prolonged fixation time, or exposure to severe heat or chemicals may give rise to inadequate results.
Five to seven business days for slides and paraffin blocks respectively. If confirmation by FISH is required: additional 5 to 7 business days.