MET (SP44) IHC Non-Squamous NSCLC

Tissue staining is dependent on the handling and processing of the tissue before staining. Improper fixation, freezing, thawing, washing, drying, heating, sectioning or contamination with other tissues or fluids may produce artifacts or false negative results. Inconsistent results may arise from variations in fixation and embedding methods.

The recommended fixative is 10% NBF. Fix samples in formalin for six to 72 hours. Zinc formalin is also acceptable for fixative time of six to 72 hours. Samples fixed in formalin and zinc formalin for fixation times less than six hours have demonstrated a loss of specific MET immunoreactivity and can lead to a false negative result. Fixatives such as AFA, PREFER fixative, Z-fix, alcohol formalin and 95% ethanol are not acceptable for use with this assay and have demonstrated a significant loss of specific MET immunoreactivity and can lead to a false negative result. When fixative type and/or fixation duration are unknown or outside of the recommended parameters, and a negative test result is obtained, consider including a statement in the pathology report that retesting with a new sample collected and prepared according to the recommended device specifications may be warranted. 

Patient tissue sections should be refrigerated (5ºC ± 3ºC) and stained within 45 days of sectioning from the tissue block. Storage outside of recommended conditions have demonstrated a loss of specific MET immunoreactivity and can lead to a false negative result. This assay has not been validated for use with cytology smears or decalcified specimens.