French multicentric validation ofALKrearrangement diagnostic in 547 lung adenocarcinomas

Abstract

Anaplastic lymphoma kinase (ALK) gene rearrangements in lung adenocarcinoma result in kinase activity targetable by crizotinib. Although fluorescence in situ hybridisation (FISH) is the reference diagnostic technique, immunohistochemistry (IHC) could be useful for pre-screening.Diagnostic yields of ALK IHC, FISH and quantitative reverse transcriptase PCR performed in 14 French pathology/molecular genetics platforms were compared. 547 lung adenocarcinoma specimens were analysed using 5A4 and D5F3 antibodies, two break-apart FISH probes and TaqMan kits. Clinicopathological data were recorded. 140 tumours were ALK rearranged (FISH with ⩾15% of rearranged cells) and 400 were ALK FISH negative (<15%). FISH was not interpretable for seven cases. ALK patients were young (p=0.003), mostly females (p=0.007) and light/nonsmokers (p<0.0001). 13 cases were IHC negative but FISH ⩾15%, including six cases with FISH between 15% and 20%; eight were IHC positive with FISH between 10% and 14%. Sensitivity and specificity for 5A4 and D5F3 were 87% and 92%, and 89% and 76%, respectively. False-negative IHC, observed in 2.4% of cases, dropped to 1.3% for FISH >20%. Variants were undetected in 36% of ALK tumours.Discordances predominated with FISH ranging from 10% to 20% of rearranged cells and were centre dependent. IHC remains a reliable pre-screening method for ALK rearrangement detection. @ERSpublications IHC is useful in pre-screening for ALK rearrangement, with FISH for confirmation of diagnosis

Custom Gene Capture and Next-Generation Sequencing to Resolve Discordant ALK Status by FISH and IHC in Lung Adenocarcinoma

“…22 Three of our 4 FISH+/IHC− cases also fell in this range (15–18%), in keeping with the results in that study. A recent study showed that approximately 6% of ALK FISH cases belong to a borderline group for which ALK FISH evaluation has of limited reliability possibly due to sampling effects.…”

“…As mentioned earlier, the positive ALK FISH results in these 3 cases were borderline (15–18%), which might explain the discordances as observed in the recent French study. 22,23 ALK FISH in the remaining 1 FISH+/IHC− case showed break apart probes in 27% of tumor cell nuclei; this case showed BIRC6->EML4 and AAK->ALK fusions by both NGS of DNA and RNAseq. In our previous study 21 , we found EML4–ALK fusion by RT-PCR followed by sequencing in this case using FFPE.…”

A comparison of ALK gene rearrangement and ALK protein expression in primary lung carcinoma and matched metastasis

“…Therefore, technical errors cannot be excluded reliably as the main reason for the discordant cases, particularly in FISH‐positive cases with negative IHC results. A similar finding was observed by Lantuejoul et al ., who reported that discordant ALK status between FISH and IHC occurred predominantly in cases with a percentage of positive tumour cells ranging between 10% and 20%.…”

The prognostic value of serum CA 19-9 for patients with advanced lung adenocarcinoma

“…We tested CA 19-9 expression, immunohistochemically (IHC), using the 116-NS-19-9 antibody (Covance Inc., Princeton, USA). We applied the expression score, which was described previously [26–28]. Percentages of CA 19-9 + tumor cells (proportion score) was scored as 0: none (0 %); 1: 1–10 %; 2: 11–30 %; 3: 31–50 %; 4: 51–70 %; and 5: 71–100 % of each tumor sample.…”