Malignant pleural effusion cell block samples had a diagnostic performance for ALK detection in advanced NSCLC that was comparable to that of tumour tissue samples. MPE cell block samples might be valid alternative samples for ALK detection when tissue is not available. Ventana IHC could be the most suitable method for ALK detection in MPE cell block samples.
Background: Detection of programmed cell death ligand-1 (PD-L1) by immunohistochemistry (IHC) has been commonly used to predict the efficacy of treatment with PD-1/PD-L1 inhibitors. However, there is limited literature regarding the reliability of PD-L1 testing using malignant pleural effusion (MPE) cell blocks. Here, we assess PD-L1 expression in sections from MPE cell blocks and evaluate the value of IHC double staining in the interpretation of PD-L1 expression. Methods: In all, 124 paired formalin-fixed tissues from advanced NSCLC patients, including MPE cell blocks and matched histology samples, were included. PD-L1 expression was assessed using the SP263 assay, and the tumor proportion score (TPS) and the staining intensity were evaluated. PD-L1 staining results were also compared between IHC double and single staining techniques. Results: PD-L1 expression was concordant in most paired cases (86/101, 85.1%) among three TPS cutoffs (<1%, 1-49% and ≥ 50%), with a kappa value of 0.774. Moreover, a significant difference in PD-L1 expression between MPE cell blocks and biopsy samples was observed (p = 0.005). For the 15 discordant pairs, 13 MPE cell block samples showed increased expression of PD-L1. Compared with the standard IHC single PD-L1 assay, double staining with anti-TTF-1 and anti-PD-L1 revealed a negative effect on PD-L1 expression testing and resulted in weaker staining intensity and a lower TPS (p = 0.000). Conclusions: MPE cell block samples are good candidates for PD-L1 expression detection in advanced NSCLC patients. The mechanism and clinical significance of the higher PD-L1 expression rate in MPE cell blocks compared with small biopsy samples remain to be evaluated prospectively.
To compare a panel of selected biomarkers between gastric primary cancer and the paired Krukenberg tumor, a total of 21 cases of metastatic tumors originating from stomach and the paired gastric primary cancers were collected. The expressions of a panel of selected biomarkers were tested by IHC. FISH was used to determine the status of HER2/neu in cases scored IHC 2+. The differences of the expressions of the biomarkers were evaluated between metastatic tumors and the paired gastric primary cancers. Bcl-2 was negative in all the cases. The HER2/neu expression was consistent between the gastric primary cancers and the paired metastatic tumors in 17 patients. In the other 4 cases, the HER2/neu expression was negative in gastric primary cancers but positive in the matched metastatic tumors. The concordance rate of c-MET, p53, and Ki-67 expression was 71.4%, 81.0%, and 76.2%, respectively. In conclusion, the expression of Bcl-2 is negative in all gastric primary tumors and the paired metastatic cancers. There is major concordance of the expression of HER2/neu, c-MET, p53, and Ki-67 between gastric primary cancers and the paired metastatic tumors, which suggests that the status of these biomarkers remain stable during the metastatic process.
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