Importance Four assays have been registered with the FDA to detect PD-L1 to enrich for patient response to anti-PD-1/PD-L1 therapies. The tests use four separate PD-L1 antibodies on two separate staining platforms and have their own scoring systems which raises questions about their similarity and potential cross-utilization. Objective We compared the performance of four PD-L1 platforms, including two FDA-cleared assays and two laboratory developed tests (LDTs). Design Four serial histology sections from 90 archival NSCLCs were distributed to three sites that performed the following IHCs: 1) 28-8 antibody on Dako Link 48; 2) 22c3 antibody on Dako Link 48; 3) SP142 antibody on Ventana Benchmark; and 4) E1L3N antibody on Leica Bond. Slides were scanned and scored by thirteen pathologists by estimating the percentage of malignant and immune cells expressing PD-L1. Intraclass correlation coefficients (ICC) and paired and mixed effects statistical analyses were performed to compare antibodies and pathologists scoring of tumor and immune cells. Results The SP142 Ventana assay was an outlier with a significantly lower mean score of PD-L1 expression in both tumor and immune cells. Pairwise comparisons showed the 28-8 and E1L3N were not significantly different, but that 22c3 showed a slight but statistically significant reduction in tumor cell labeling. Evaluation of ICC between antibodies to quantify inter-assay variability using the average of thirteen pathologists scores for tumor shows very high concordance between antibodies for tumor cell scoring (0.813) and lower levels of concordance for immune cell scoring (0.277). When examining inter-pathologists variability for any single antibody, the concordance between pathologists’ reads for tumor ranged from ICC of 0.83 to 0.88 for each antibody while the ICC from immune cells for each antibody ranged from 0.17 to 0.23. Conclusions The assay using the SP142 antibody is a clear outlier detecting significantly less tumor cell and immune cell PD-L1 expression. Antibody 22c3 shows slight yet statistically significantly lower staining than either 28-8 or E1L3N, but this significance is only detected when using the average of thirteen pathologist scores. Pathologists show excellent concordance when scoring tumor cells stained with any antibody, but poor concordance for scoring immune cell staining.

We have developed an extracorporeal system for investigating in vitro the biofilm-adherent bacterial microcolonies (BABM) that grow on Tenckhoff catheters (TC), to study peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A modified Robbins’ device, attached to sampling plugs with TC discs and connected to the dialysate via a peristaltic pump, is run for 24 h; scrapings from pairs of TC discs are processed for assessment of viable BABM, one of each pair for culture by routine microbiology techniques and the other for examination by scanning and transmission electron microscopy (EM). No colonization was noted with fresh dialysis solutions and spent dialysates from patients without clinical peritonits; but, when bacterial suspensions were added to aliquots of the same dialysates, BABM were noted on both culture and EM. In a study of 4 patients on CAPD treatment, who had clinically evident peritonitis, routine cultures of spent dialysate were positive in only 2, but BABM were found in cultures and EM preparations of disc scrapings in all 4 cases. We conclude from these preliminary findings that this extracorporeal system is reliable, and well suited for studying the role of BABM in CAPD-associated peritonitis in vitro.

AimsAt the time of analysis, two widely used, drug-specific, tumour-cell programmed death ligand 1 (PD-L1) assays were approved by the US Food and Drug Administration for anti-PD-1 therapies: the Dako PD-L1 immunohistochemistry (IHC) 28-8 pharmDx assay and the Dako PD-L1 IHC 22C3 pharmDx assay. Given that the majority of current PD-L1 testing in US clinical practice is performed at commercial reference laboratories, we aimed to evaluate the concordance of the 28-8 and 22C3 assays in a real-world setting.MethodsMatched PD-L1 IHC 28-8 and 22C3 results from routine assessment were obtained from 1930 patients, including 412 confirmed to have lung cancer, submitted from hospitals in over 38 US states/territories. Biopsies were stained, reviewed and scored by trained/certified pathologists at a single cancer reference laboratory between 2015 and 2017. Rate of concordance between assay findings was assessed by Bland-Altman analysis; overall per cent agreement (OPA), positive per cent agreement and negative per cent agreement; and Cohen’s kappa.ResultsPD-L1 IHC 28-8 and 22C3 displayed strong correlation across all samples and in samples with a confirmed lung cancer diagnosis irrespective of biopsy site. The OPA was 97%–98% for all samples, depending on the expression level defining PD-L1 positivity. In the Bland-Altman analysis, the mean difference in percentage of tumour cells positively stained for PD-L1 between the paired assay findings was –0.80% for all samples and –0.93% in samples with a confirmed lung cancer diagnosis.ConclusionsThese data, in conjunction with recent findings, support the analytical concordance of the PD-L1 IHC 28-8 and 22C3 assays for assessing per cent tumour-cell membrane PD-L1 expression.

The molecular differences between ischemic (IF) and non-ischemic (NIF) heart failure are poorly defined. A better understanding of the molecular differences between these two heart failure etiologies may lead to the development of more effective heart failure therapeutics. In this study extensive proteomic and phosphoproteomic profiles of myocardial tissue from patients diagnosed with IF or NIF were assembled and compared.Proteins extracted from left ventricular sections were proteolyzed and phosphopeptides were enriched using titanium dioxide resin. Gel- and label-free nanoscale capillary liquid chromatography coupled to high resolution accuracy mass tandem mass spectrometry allowed for the quantification of 4,436 peptides (corresponding to 450 proteins) and 823 phosphopeptides (corresponding to 400 proteins) from the unenriched and phospho-enriched fractions, respectively.Protein abundance did not distinguish NIF from IF. In contrast, 37 peptides (corresponding to 26 proteins) exhibited a ≥2-fold alteration in phosphorylation state (p<0.05) when comparing IF and NIF. The degree of protein phosphorylation at these 37 sites was specifically dependent upon the heart failure etiology examined. Proteins exhibiting phosphorylation alterations were grouped into functional categories: transcriptional activation/RNA processing; cytoskeleton structure/function; molecular chaperones; cell adhesion/signaling; apoptosis; and energetic/metabolism.Phosphoproteomic analysis demonstrated profound post-translational differences in proteins that are involved in multiple cellular processes between different heart failure phenotypes. Understanding the roles these phosphorylation alterations play in the development of NIF and IF has the potential to generate etiology-specific heart failure therapeutics, which could be more effective than current therapeutics in addressing the growing concern of heart failure.