ALK-Rearranged Lung Cancer in Chinese: A Comprehensive Assessment of Clinicopathology, IHC, FISH and RT-PCR

Abstract

Approximately 3–7% of non-small cell lung cancers harbor an anaplastic lymphoma kinase (ALK) gene fusion, constituting a new molecular subtype of lung cancer that responds to crizotinib, an ALK inhibitor. Although previous studies have evaluated ALK-rearranged lung cancers, the comprehensive analysis of lung cancer in Chinese has not well assessed. Herein, we identified 44 cases of ALK-rearranged samples by fluorescent in-situ hybridization (FISH), immunohistochemistry (IHC), and reverse transcription polymerase chain reaction (RT-PCR) in a large number of surgically resected lung cancers. All 44 ALK-rearranged lung cancers were adenocarcinomas, with 2 cases having additional focal squamous components. The goal was to analyse the clinicopathological features of ALK-rearranged lung adenocarcinomas. Our data showed that a cribriform structure, prominent extracellular mucus and any type of mucous cell pattern may be either sensitive or specific to predict an ALK rearrangement. We used FISH as the standard detection method. We compared the ALK rearrangement accuracy of FISH, RT-PCR and IHC. RT-PCR could define both the ALK fusion partner and the fusion variant, but seemed unable to detect all translocations involving the ALK gene. It is noteworthy that IHC using the D5F3 antibody (Cell Signaling Technology) showed higher sensitivity and specificity than the ALK1 antibody (Dako). Therefore, we conclude that IHC remains a cost-effective and efficient technique for diagnosing ALK rearrangements and that D5F3 can be the optimal screening antibody in clinical practice.

MET overexpression and amplification define a distinct molecular subgroup for targeted therapies in gastric cancer

“…For MET analysis, tumors with a MET/ CEP7 ratio of C2, the presence of tight gene clusters, or C15 copies of the gene in C10 % tumor cells were considered to show amplification, as previously reported [24,29]. When samples displayed more than 15 % breakapart signals or isolated red signals in 50 tumor cells, ROS1 or ALK rearrangements were scored as positive [30,31].…”

ALK-rearrangements and testing methods in non-small cell lung cancer: a review

“…Although ALK fusion proteins can coexist with other lung cancer driver mutations, these molecular double-hits are rare [8,102-015]. This observation is not surprising as small interfering RNA silencing of the EML4-Alk fusion in cell lines inhibits cell growth more than 50%, indicating that the EML4-ALK fusion, by itself, is sufficient as a malignancy driver mutation [72].…”

“…In 2011 FDA approved the Abbot Vysis ALK Break Apart FISH Probe Kit for molecular diagnostic testing [110,111]. For the Vysis ALK procedure unstained tissue hybridized overnight with the ALK probe and is evaluated by fluorescence microscopy [102,110,112,113]. An ALK translocation is present when the ALK probe shows separated red and green fluorophores, or has loss of the green signal, in 15% or more of the cells examined.…”

Anaplastic lymphoma kinase: Role in cancer and therapy perspective

“…The amplicons can be sequenced to identify the specific fusion variants. [63][64][65] The RT-PCR method is targeted to one partner gene per run; it is limited to the primer sequence located on the partner gene and ALK gene. Quantitative RT-PCR can detect mRNA amount differences, which are appropriate to test overexpression of fusion and non-fusion ALK.…”