Purpose PD-1 inhibitors are established agents in the management of non-small cell lung cancer (NSCLC); however, only a subset of patients derives clinical benefit. To determine the activity of PD-1/PD-L1 inhibitors within clinically-relevant molecular subgroups, we retrospectively evaluated response patterns among EGFR-mutant, ALK-positive, and EGFR wild-type/ALK-negative patients. Experimental Design We identified 58 patients treated with PD-1/PD-L1 inhibitors. Objective response rates (ORRs) were assessed using RECIST v1.1. PD-L1 expression and CD8+ tumor infiltrating lymphocytes (TILs) were evaluated by immunohistochemistry. Results Objective responses were observed in 1/28 (3.6%) EGFR-mutant or ALK-positive patients versus 7/30 (23.3%) EGFR wild-type and ALK-negative/unknown patients (P = 0.053). The ORR among never- or light- (≤10 pack years) smokers was 4.2% versus 20.6% among heavy smokers (P = 0.123). In an independent cohort of advanced, EGFR-mutant (N=68) and ALK-positive (N=27) patients, PD-L1 expression was observed in 24%/16%/11% and 63%/47%/26% of pre-tyrosine kinase inhibitor (TKI) biopsies using cutoffs of ≥1%, ≥5% and ≥50% tumor cell staining, respectively. Among EGFR-mutant patients with paired, pre- and post-TKI resistant biopsies (N=57), PD-L1 expression levels changed after resistance in 16 (28%) patients. Concurrent PD-L1 expression (≥5%) and high levels of CD8+ TILs (grade ≥2) were observed in only 1 pre-treatment (2.1%) and 5 resistant (11.6%) EGFR-mutant specimens, and was not observed in any ALK-positive, pre- or post-TKI specimens. Conclusion NSCLCs harboring EGFR mutations or ALK rearrangements are associated with low ORRs to PD-1/PD-L1 inhibitors. Low rates of concurrent PD-L1 expression and CD8+ TILs within the tumor microenvironment may underlie these clinical observations.

Progress in understanding, diagnosis, and treatment of coronary artery disease (CAD) has been hindered by our inability to observe cells and extracellular components associated with human coronary atherosclerosis in situ. The current standards for microstructural investigation, histology and electron microscopy, are destructive and prone to artifacts. The highest resolution intracoronary imaging modality, optical coherence tomography (OCT), has a resolution of ~10μm, which is too coarse for visualizing most cells. Here we report a new form of OCT, termed μOCT that has an order of magnitude improved resolution. We show that μOCT images of cadaver coronary arteries provide clear pictures of cellular and subcellular features associated with atherogenesis, thrombosis, and response to interventional therapy. These results suggest that μOCT can complement existing diagnostic techniques for investigating atherosclerotic specimens today and may in the future become a useful tool for cellular and subcellular characterization of the human coronary wall in vivo.

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BackgroundOnly prototypes 5 years ago, high-speed, automated whole slide imaging (WSI) systems (also called digital slide systems, virtual microscopes or wide field imagers) are becoming increasingly capable and robust. Modern devices can capture a slide in 5 minutes at spatial sampling periods of less than 0.5 micron/pixel. The capacity to rapidly digitize large numbers of slides should eventually have a profound, positive impact on pathology. It is important, however, that pathologists validate these systems during development, not only to identify their limitations but to guide their evolution.MethodsThree pathologists fully signed out 25 cases representing 31 parts. The laboratory information system was used to simulate real-world sign-out conditions including entering a full diagnostic field and comment (when appropriate) and ordering special stains and recuts. For each case, discrepancies between diagnoses were documented by committee and a "consensus" report was formed and then compared with the microscope-based, sign-out report from the clinical archive.ResultsIn 17 of 25 cases there were no discrepancies between the individual study pathologist reports. In 8 of the remaining cases, there were 12 discrepancies, including 3 in which image quality could be at least partially implicated. When the WSI consensus diagnoses were compared with the original sign-out diagnoses, no significant discrepancies were found. Full text of the pathologist reports, the WSI consensus diagnoses, and the original sign-out diagnoses are available as an attachment to this publication.ConclusionThe results indicated that the image information contained in current whole slide images is sufficient for pathologists to make reliable diagnostic decisions and compose complex diagnostic reports. This is a very positive result; however, this does not mean that WSI is as good as a microscope. Virtually every slide had focal areas in which image quality (focus and dynamic range) was less than perfect. In some cases, there was evidence of over-compression and regions made "soft" by less than perfect focus. We expect systems will continue to get better, image quality and speed will continue to improve, but that further validation studies will be needed to guide development of this promising technology.

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Tumor islands -large collections of tumor cells isolated within alveolar spaces -can be seen in lung adenocarcinomas. Recently we observed by 3D reconstruction that these structures were connected with each other and with the main tumor in different tissue planes, raising the possibility of tumor islands being a means of invasion. However, the clinical and prognostic significance of tumor islands remain unknown. In this study, we compared clinicopathological and molecular characteristics and prognosis of Stage I-II lung adenocarcinomas with tumor islands (n=58) and those without (n=203). Lung adenocarcinomas with tumor islands were more likely to occur in smokers, exhibit higher nuclear grade and a solid or micropapillary pattern of growth, and harbor KRAS mutations. In contrast, lung adenocarcinomas without tumor islands were more likely to present as minimally invasive adenocarcinoma, show a lepidic pattern of growth, and harbor EGFR mutations. Although there was no difference in stage, the prognosis of lung adenocarcinomas with tumor islands was significantly worse than those without. The five-year recurrence-free survival for patients with tumor islands and those without was 44.6% and 74.4%, respectively (log-rank p = 0.010). The survival difference remained significant (p < 0.020) by multivariate analysis, and the presence of tumor islands was associated with almost two-fold increase in the risk of recurrence. Even in the Stage IA cohort, more than half of the patients with tumor islands experienced recurrence within 5 years. Thus, aggressive surveillance and/or further intervention may be indicated for patients whose tumors exhibit tumor islands.

Chromosomal rearrangements leading to constitutive activation of anaplastic lymphoma receptor tyrosine kinase (ALK) define a category of lung adenocarcinomas that may be amenable to targeted therapy with the ALK inhibitor crizotinib. Defining distinctive features of ALK-rearranged (ALK þ ) lung adenocarcinomas may help identify cases that merit molecular testing. However, data describing the morphologic features of ALK þ lung adenocarcinomas are conflicting and are primarily based on analysis of resected primary lung tumors. It is unclear whether the findings from prior studies are applicable to metastatic lung tumors or to small biopsy/ cytology specimens. To address these issues, we examined resection, excision, small biopsy, and cytology cell block specimens from 104 ALK þ and 215 ALKÀ lung adenocarcinomas from primary and metastatic sites. All cases were evaluated for ALK rearrangements by fluorescence in situ hybridization. The predominant histologic subtypes and distinctive cytomorphologic features were assessed in each case. Primary ALK þ lung adenocarcinomas showed a significant association with solid, micropapillary, and papillary-predominant histologic patterns and tumor cells with a signet ring or hepatoid cytomorphology. Among metastatic lung tumors and small biopsy/cytology specimens, the only distinguishing morphologic feature of ALK þ tumors was the presence of signet ring cells. Based on these results, we developed a morphology-based scoring system for predicting ALK rearrangements in lung adenocarcinomas. The scoring system predicted ALK rearrangements in a new cohort of 78 lung adenocarcinomas (29 ALK þ and 49 ALKÀ) with a sensitivity of 88% and a specificity of 45%. In conclusion, ALK þ lung adenocarcinomas have distinctive morphologic features, with signet ring cells showing a significant association with ALK rearrangements irrespective of tumor site (primary vs metastatic) or specimen type. However, morphologic screening alone will not detect a minority of ALK þ lung adenocarcinomas, and the routine use of ancillary studies may be warranted to identify all patients who may benefit from crizotinib treatment.