ALK Protein Analysis by IHC Staining after Recent Regulatory Changes: A Comparison of Two Widely Used Approaches, Revision of the Literature, and a New Testing Algorithm

Abstract

Our results confirm the difficulty in managing an IHC test without amplification in the absence of confirmatory FISH analysis, as well as the possibility of performing a direct diagnosis in approximately 90% of patients by the VENTANA ALK (D5F3) CDx Assay. On the basis of the recent regulatory changes, the data that have emerged from the literature, and the results of the present study, a new algorithm for ALK assessment in non-small cell lung cancer has been devised.

New Approaches for Successful Identification of Several Gene Fusion Oncogenes in Paraffin-Embedded Tissue Samples from Advanced Non- Small-Cell Lung Cancer Patients

“…One of the FISH-negative and nCounter-positive patients had complete clinical follow-up, being on partial response to crizotinib for more than three years [8]. These results, along with the recent published cases of responses in ALK FISH-negative/IHC-positive patients treated with ALK inhibitors [12,13] questions FISH as the technique of choice for screening and illustrates the clinical importance of identifying ALK gene expression rather than the chromosome alteration itself, which indeed, is one of the advantages of nCounter-based transcript technology.…”

Anaplastic lymphoma tyrosine kinase oncogene in human cancer: gene aberrations, methods of detection and therapeutic potential

“…ALK D5F3 staining results were evaluated using a binary scoring system as positive or negative following the manufacturer's instructions. 63 …”

Tackling ALK in non-small cell lung cancer: the role of novel inhibitors

“…In a recent study (46), the sensitivity and specificity were 43% and 98% for FISH and 100% and 98% for IHC, respectively. Relevant discrepancies between FISH and IHC results have indeed been reported (47)(48)(49). Importantly, patients responding to ALK inhibitors with an ALK IHC-positive but FISHnegative adenocarcinoma have been extensively described (49,50 (Figure 2).…”

“…Relevant discrepancies between FISH and IHC results have indeed been reported (47)(48)(49). Importantly, patients responding to ALK inhibitors with an ALK IHC-positive but FISHnegative adenocarcinoma have been extensively described (49,50 (Figure 2). D5F3 and 5A4 with an appropriate highly sensitive amplification kit are the best clones when using a platform different from Ventana/ Roche, while the Ventana/Roche CDx D5F3 is the most adequate IHC system when a Ventana/Roche platform is available in the own lab (49).…”