Various programed death ligand 1 (PD-L1) immunohistochemistry (IHC) assays have been developed and used in clinical trials in association with different drugs. In order to harmonize and make PD-L1 ...testing in non-small-cell lung cancer (NSCLC) widely available, we conducted a multicenter study comparing PD-L1 standardized assays and laboratory-developed tests (LDTs).
IHC with five anti-PD-L1 monoclonal antibodies (28-8, 22C3, E1L3N, SP142 and SP263) was performed concomitantly on 41 NSCLC surgical specimens in 7 centers using Dako Autostainer Link 48 (3 centers), Leica Bond (2 centers) or Ventana BenchMark Ultra (2 centers) platforms. For each matching platform, 22C3, 28-8 and SP263 assays were performed. For nonmatching platforms and other antibodies, LDTs were developed in each center. A total of 35 stainings were performed for each case across different platforms and antibodies. PD-L1 staining was assessed in tumor cells and immune cells by seven trained thoracic pathologists. For statistical analysis, 1%, 50% and 1%, 5%, 10% expression thresholds were used for tumor cells and immune cells, respectively.
28-8, 22C3 and SP263 assays were highly concordant for tumor cells staining across the five Dako or Ventana platforms. Among 27 LDTs developed in 7 centers on Dako, Ventana and Leica platforms, 14 (51.8%) demonstrated similar concordance when compared with reference assays for tumor cell staining. Clone SP263 achieved the highest concordance rate across all platforms. Lower concordance was observed for immune cells staining when using a four categories scale.
28-8, 22C3 and SP263 assays had close analytical performance for tumor cell staining across seven centers. Some LDTs on Dako, Ventana and Leica platforms achieved similar concordance, but caution is warranted for their validation. These LDTs will be further validated in order to provide recommendations for the use of assays and LDT for PD-L1 testing in NSCLC.
Angiogenesis is a key feature of liver fibrosis. Although sinusoidal remodeling is believed to contribute to fibrogenesis, the impact of sinusoidal angiogenesis on the resolution of liver fibrosis ...remains undefined. Myeloid cells, particularly macrophages, constantly infiltrate the fibrotic liver and can profoundly contribute to remodeling of liver sinusoids. We observe that the development of fibrosis is associated with decreased hepatic vascular endothelial growth factor (VEGF) expression as well as sinusoidal rarefication of the fibrotic scar. In contrast, the resolution of fibrosis is characterized by a rise in hepatic VEGF levels and revascularization of the fibrotic tissue. Genetic ablation of VEGF in myeloid cells or pharmacological inhibition of VEGF receptor 2 signaling prevents this angiogenic response and the resolution of liver fibrosis. We observe increased expression of matrix metalloproteases as well as decreased expression of tissue inhibitor of metalloproteases confined to sinusoidal endothelial cells in response to myeloid cell VEGF. Remarkably, reintroduction of myeloid cell–derived VEGF upon recovery restores collagenolytic acitivity and the resolution of fibrosis. Conclusion: We identify myeloid cell–derived VEGF as a critical regulator of extracellular matrix degradation by liver endothelial cells, thereby unmasking an unanticipated link between angiogenesis and the resolution of fibrosis. (Hepatology 2015;61:2042–2055)
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