Activation of CD8+ T Cells in Chronic Obstructive Pulmonary Disease Lung

Rationale: Despite the importance of inflammation in chronic obstructive pulmonary disease (COPD), the immune cell landscape in the lung tissue of patients with mild-moderate disease has not been well characterized at the single-cell and molecular level. Objectives: To define the immune cell landscape in lung tissue from patients with mild-moderate COPD at single-cell resolution. Methods: We performed single-cell transcriptomic, proteomic, and T-cell receptor repertoire analyses on lung tissue from patients with mild-moderate COPD (n = 5, Global Initiative for Chronic Obstructive Lung Disease I or II), emphysema without airflow obstruction (n = 5), end-stage COPD (n = 2), control (n = 6), or donors (n = 4). We validated in an independent patient cohort (N = 929) and integrated with the Hhip+/- murine model of COPD. Measurements and Main Results: Mild-moderate COPD lungs have increased abundance of two CD8+ T cell subpopulations: cytotoxic KLRG1+TIGIT+CX3CR1+ TEMRA (T effector memory CD45RA+) cells, and DNAM-1+CCR5+ T resident memory (TRM) cells. These CD8+ T cells interact with myeloid and alveolar type II cells via IFNG and have hyperexpanded T-cell receptor clonotypes. In an independent cohort, the CD8+KLRG1+ TEMRA cells are increased in mild-moderate COPD lung compared with control or end-stage COPD lung. Human CD8+KLRG1+ TEMRA cells are similar to CD8+ T cells driving inflammation in an aging-related murine model of COPD. Conclusions: CD8+ TEMRA cells are increased in mild-moderate COPD lung and may contribute to inflammation that precedes severe disease. Further study of these CD8+ T cells may have therapeutic implications for preventing severe COPD.

Lymphangioleiomyomatosis: circulating levels of FGF23 and pulmonary diffusion

OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare, destructive disease of the lungs with a limited number of determinants of disease activity, which are a critical need for clinical trials. FGF23 has been implicated in several chronic pulmonary diseases. We aimed to determine the association between serum FGF23 levels and pulmonary function in a cohort of patients with LAM.

METHODS

This was a descriptive single-center study in which subjects with LAM and controls with unreported lung disease were recruited. Serum FGF23 levels were measured in all subjects. Clinical data, including pulmonary function testing, were retrospectively obtained from electronic medical records of LAM subjects. Associations between FGF23 levels and clinical features of LAM were explored via nonparametric hypothesis testing.

RESULTS

The sample comprised 37 subjects with LAM and 16 controls. FGF23 levels were higher in the LAM group than in the control group. In the LAM group, FGF23 levels above the optimal cutoff point distinguished 33% of the subjects who had nondiagnostic VEGF-D levels. Lower FGF23 levels were associated with impaired DLCO (p = 0.04), particularly for those with isolated diffusion impairment with no other spirometric abnormalities (p = 0.04).

CONCLUSIONS

Our results suggest that FGF23 is associated with pulmonary diffusion abnormalities in LAM patients and elicit novel mechanisms of LAM pathogenesis. FGF23 alone or in combination with other molecules needs to be validated as a biomarker of LAM activity in future clinical research.

Activation of Tumor-Cell STING Primes NK-Cell Therapy

Activation of the stimulator of interferon genes (STING) pathway promotes antitumor immunity but STING agonists have yet to achieve clinical success. Increased understanding of the mechanism of action of STING agonists in human tumors is key to developing therapeutic combinations that activate effective innate antitumor immunity. Here, we report that malignant pleural mesothelioma cells robustly express STING and are responsive to STING agonist treatment ex vivo. Using dynamic single-cell RNA sequencing of explants treated with a STING agonist, we observed CXCR3 chemokine activation primarily in tumor cells and cancer-associated fibroblasts, as well as T-cell cytotoxicity. In contrast, primary natural killer (NK) cells resisted STING agonist-induced cytotoxicity. STING agonists enhanced migration and killing of NK cells and mesothelin-targeted chimeric antigen receptor (CAR)-NK cells, improving therapeutic activity in patient-derived organotypic tumor spheroids. These studies reveal the fundamental importance of using human tumor samples to assess innate and cellular immune therapies. By functionally profiling mesothelioma tumor explants with elevated STING expression in tumor cells, we uncovered distinct consequences of STING agonist treatment in humans that support testing combining STING agonists with NK and CAR-NK cell therapies.

Cross-tissue, single-cell stromal atlas identifies shared pathological fibroblast phenotypes in four chronic inflammatory diseases

BACKGROUND

Pro-inflammatory fibroblasts are critical for pathogenesis in rheumatoid arthritis, inflammatory bowel disease, interstitial lung disease, and Sjögren's syndrome and represent a novel therapeutic target for chronic inflammatory disease. However, the heterogeneity of fibroblast phenotypes, exacerbated by the lack of a common cross-tissue taxonomy, has limited our understanding of which pathways are shared by multiple diseases.

METHODS

We profiled fibroblasts derived from inflamed and non-inflamed synovium, intestine, lungs, and salivary glands from affected individuals with single-cell RNA sequencing. We integrated all fibroblasts into a multi-tissue atlas to characterize shared and tissue-specific phenotypes.

FINDINGS

Two shared clusters, CXCL10+CCL19+ immune-interacting and SPARC+COL3A1+ vascular-interacting fibroblasts, were expanded in all inflamed tissues and mapped to dermal analogs in a public atopic dermatitis atlas. We confirmed these human pro-inflammatory fibroblasts in animal models of lung, joint, and intestinal inflammation.

CONCLUSIONS

This work represents a thorough investigation into fibroblasts across organ systems, individual donors, and disease states that reveals shared pathogenic activation states across four chronic inflammatory diseases.

FUNDING

Grant from F. Hoffmann-La Roche (Roche) AG.

Diagnostic criteria and evolving molecular characterization of pulmonary neuroendocrine carcinomas

Neuroendocrine carcinomas of the lung are currently classified into two categories: small cell lung carcinoma and large cell neuroendocrine carcinoma. Diagnostic criteria for small cell- and large cell neuroendocrine carcinoma are based solely on tumor morphology; however, overlap in histologic and immunophenotypic features between the two types of carcinoma can potentially make their classification challenging. Accurate diagnosis of pulmonary neuroendocrine carcinomas is paramount for patient management, as clinical course and treatment differ between small cell and large cell neuroendocrine carcinoma. Molecular-genetic, transcriptomic, and proteomic data published over the past decade suggest that small cell and large cell neuroendocrine carcinomas are not homogeneous categories but rather comprise multiple groups of distinctive malignancies. Nuances in the susceptibility of small cell lung carcinoma subtypes to different chemotherapeutic regimens and the discovery of targetable mutations in large cell neuroendocrine carcinoma suggest that classification and treatment of neuroendocrine carcinomas may be informed by ancillary molecular and protein expression testing going forward. This review summarizes current diagnostic criteria, prognostic and predictive correlates of classification, and evidence of previously unrecognized subtypes of small cell and large cell neuroendocrine carcinoma.

Abstract 4168: Tumor cell stimulator of interferon genes (STING) activation primes NK cell therapy in mesothelioma

Background: Activation of the anti-viral STING pathway promotes antitumor immunity but STING agonists have yet to achieve clinical success. Understanding their mechanism of action in human tumors is key to developing STING-based therapies and combinations. Higher tumor STING expression correlates with better response to treatment and multiple cancers have been shown to silence STING and the downstream interferon response to avoid immune detection, demonstrating an important role for tumor cell STING in antitumor immunity. Recent mouse studies have explored the complex interplay of STING activation in the tumor immune microenvironment (TIME), identifying unexpected T-cell toxicity and novel effector mechanisms including NK cells. Yet how STING agonists impact the human TIME has not been carefully examined and could inform development of novel therapeutic combinations. Here we address this question using human tumors cultured ex vivo to maintain the TIME, dissecting STING agonist response in malignant pleural mesothelioma (MPM), an inflamed cancer with high STING expression.

Methods: We performed STING immunohistochemistry on 300 thoracic tumor specimens, followed by functional ex vivo studies of STING agonist response in human mesothelioma explants, measuring cell death and cytokine production. Dynamic single cell RNA sequencing was performed after treatment with a STING agonist. Primary human T-cells and NK cells were used to study STING agonist toxicity in the context of STING cycling and patient derived organotypic tumor spheroids (PDOTS) were treated for six days with STING agonists +/- NK and anti-mesothelin chimeric antigen receptor (CAR)-NK cell therapies.

Results: Amongst thoracic cancers, MPM robustly expressed tumor cell STING and was responsive to STING agonist treatment ex vivo. We observed tumor cell death >20%, p<0.05 in 12/35 MPM PDOTS after STING agonist treatment. Cell death was prevented by CD8 neutralizing antibody co-treatment. Dynamic single-cell RNA sequencing of MPM explants treated with a STING agonist unveiled CXCR3 chemokine activation primarily in tumor cells and cancer associated fibroblasts, coupled with an interferon stimulated gene program. However, STING agonism was also toxic to T-cells. In contrast, primary NK cells manifested rapid STING turnover and resisted STING agonist-induced toxicity. STING agonists enhanced NK and especially anti-mesothelin CAR-NK cell migration and killing, improving therapeutic activity in MPM PDOTS.

Conclusions: MPM, an inflamed cancer type with marginal response to immune checkpoint blockade, demonstrated high tumor cell STING expression and response to STING agonists in combination with NK cell therapies ex vivo. These studies reveal the fundamental importance of using human tumor samples to assess innate and cellular immune therapies, identifying STING agonism as an effective strategy to prime NK cell therapy.

Citation Format: Erik H. Knelson, Elena Ivanova, Mubin Tarannum, Marco Campisi, Patrick H. Lizotte, Matthew A. Booker, Brittany Meisenheimer, Minyue Chen, Nathaniel Spicer, Bonje Obua, Ha V. Vo, Thomas P. Albertson, Marina Vivero, Michael Y. Tolstorukov, Rizwan Romee, Cloud P. Paweletz, Raphael Bueno, David A. Barbie. Tumor cell stimulator of interferon genes (STING) activation primes NK cell therapy in mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4168.

Plasticity in the Absence of NOTCH Uncovers a RUNX2-Dependent Pathway in Small Cell Lung Cancer

Neuroendocrine to nonneuroendocrine plasticity supports small cell lung cancer (SCLC) tumorigenesis and promotes immunogenicity. Approximately 20% to 25% of SCLCs harbor loss-of-function (LOF) NOTCH mutations. Previous studies demonstrated that NOTCH functions as a SCLC tumor suppressor, but can also drive nonneuroendocrine plasticity to support SCLC growth. Given the dual functionality of NOTCH, it is not understood why SCLCs select for LOF NOTCH mutations and how these mutations affect SCLC tumorigenesis. In a CRISPR-based genetically engineered mouse model of SCLC, genetic loss of Notch1 or Notch2 modestly accelerated SCLC tumorigenesis. Interestingly, Notch-mutant SCLCs still formed nonneuroendocrine subpopulations, and these Notch-independent, nonneuroendocrine subpopulations were driven by Runx2-mediated regulation of Rest. Notch2-mutant nonneuroendocrine cells highly express innate immune signaling genes including stimulator of interferon genes (STING) and were sensitive to STING agonists. This work identifies a Notch-independent mechanism to promote nonneuroendocrine plasticity and suggests that therapeutic approaches to activate STING could be selectively beneficial for SCLCs with NOTCH2 mutations. SIGNIFICANCE: A genetically engineered mouse model of NOTCH-mutant SCLC reveals that nonneuroendocrine plasticity persists in the absence of NOTCH, driven by a RUNX2-REST-dependent pathway and innate immune signaling.

INSM1 expression in a subset of thoracic malignancies and small round cell tumors: rare potential pitfalls for small cell carcinoma

INSM1 is a diagnostic marker for neuroendocrine tumors originating in multiple anatomic sites. In the lung, INSM1 shows 76-97% sensitivity for neuroendocrine tumors overall. Our aim was to characterize INSM1 as a diagnostic marker for small cell carcinoma in the context of its epithelial, lymphoid, and mesenchymal morphologic mimics. Immunohistochemistry was performed on 231 tumors, including lung neuroendocrine tumors, nonneuroendocrine carcinomas of the thoracic cavity, diffuse large B-cell lymphomas, and small round cell sarcomas, using an anti-INSM1 mouse monoclonal antibody. Extent (0-100%) and intensity (1-3+) of nuclear INSM1 staining was multiplied in each case to calculate an H-score. Demographic and clinical information was obtained from the medical record. INSM1 had an overall sensitivity and specificity of 81.5% and 82.7% for small cell carcinoma, respectively, using a threshold established with a receiver operating characteristic curve. 40/48 (82.7%) small cell carcinomas were positive for INSM1, including 19/24 (79%) small cell carcinomas that were negative for chromogranin and synaptophysin. 5/5 carcinoids and 21/28 (75%) large cell neuroendocrine carcinomas showed INSM1 expression. Among nonneuroendocrine tumors, 7/38 (18%) lung adenocarcinomas, 2/17 (12%) lung squamous cell carcinomas, 4/10 (40%) thymic carcinomas, 4/12 (33%) adenoid cystic carcinomas, 1/19 (5%) diffuse large B-cell lymphomas, 4/11 (36%) alveolar rhabdomyosarcomas, and 4/23 (17%) Ewing sarcomas were positive for INSM1. No synovial sarcomas or desmoplastic small round cell tumors were positive. Weak, focal INSM1 expression alone is insufficient as a diagnostic marker for small cell carcinoma, but is sensitive and specific, easy to interpret in small biopsies, and makes a valuable addition to a diagnostic panel.

Anti-PD-1 Immunotherapy-Induced Flare of a Known Underlying Relapsing Vasculitis Mimicking Recurrent Cancer

Safe use of immune checkpoint blockade in patients with cancer and autoimmune disorders requires a better understanding of the pathophysiology of immunologic activation. We describe the immune correlates of reactivation of granulomatosis with polyangiitis (GPA)-an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis-in a patient with metastatic urothelial carcinoma treated with pembrolizumab. After PD-1 blockade, an inflammatory pulmonary nodule demonstrated a granulomatous, CD4+ T-cell infiltrate, correlating with increased CD4+ and CD8+ naïve memory cells in the peripheral blood without changes in other immune checkpoint receptors. Placed within the context of the existing literature on GPA and disease control, our findings suggest a key role for PD-1 in GPA self-tolerance and that selective strategies for immunotherapy may be needed in patients with certain autoimmune disorders. We further summarize the current literature regarding reactivation of autoimmune disorders in patients undergoing immune checkpoint blockade, as well as potential immunosuppressive strategies to minimize the risks of further vasculitic reactivation upon rechallenge with anti-PD-1 blockade. KEY POINTS: Nonspecific imaging findings in patients with cancer and rheumatological disorders may require biopsy to distinguish underlying pathology.Patients with rheumatologic disorders have increased risk of reactivation with PD-(L)1 immune checkpoint blockade, requiring assessment of disease status before starting treatment.Further study is needed to evaluate the efficacy of treatment regimens in preventing and controlling disease reactivation.

Incidental nonneoplastic parenchymal findings in patients undergoing lung resection for mass lesions

The prevalence of incidental nonneoplastic lung disease in patients undergoing resection for mass lesions is unknown. We determined the prevalence and characteristics of parenchymal findings in patients with lung nodules, aiming to increase awareness of findings that could potentially impact patient management. A total of 397 patients with benign or malignant mass lesions with available presurgical chest computed tomography scans resected between January 2001 and July 2015 were included. Retrospective histologic assessment of parenchymal abnormalities in at least 1 section of grossly normal lung was performed for each case by 2 pulmonary pathologists and correlated with original pathology reports, clinical history, and radiologic findings. A total of 233 women and 164 men underwent resections for carcinomas (78%) or benign nodules (22%). One hundred one (25%) patients showed parenchymal abnormalities, including 14 patients with multiple findings. The most common abnormal findings were fibrotic interstitial changes (10%), including usual interstitial pneumonia (1%), followed by granulomatous processes (8%). Other findings included aspiration (4%), intravascular thrombi (2%), Langerhans cell histiocytosis (1.5%), constrictive bronchiolitis (1%), atypical lymphoid infiltrates (1%), and amyloidosis (0.5%). Abnormalities were more likely to have been documented in the original pathology report by pulmonary pathologists (68%) than by general pathologists (15%) (P < .0001). Cases with histologic parenchymal abnormalities were more likely to show radiologic interstitial lung abnormalities than those without (16% versus 5%; P = .001). Evaluation of background lung parenchyma may yield valuable and unanticipated information in patients undergoing surgical resections for lung masses that may correlate with radiographic interstitial lung abnormalities and influence clinical management.

Updates in Effusion Cytology

Effusion cytology plays multiple roles in the management of benign and malignant disease, from primary diagnosis to tissue allocation for ancillary diagnostic studies and biomarker testing of therapeutic targets. This article summarizes recent advances in pleural effusion cytology, with a focus on the practical application of immunohistochemical markers, cytogenetic techniques, flow cytometry, and molecular techniques for the diagnosis and management of primary and secondary neoplasms of the pleura.

Molecular Testing of Nodules with a Suspicious or Malignant Cytologic Diagnosis in the Setting of Non-Invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP)

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is an indolent thyroid tumor characterized by frequent RAS mutations and an absence of the BRAF V600E mutation commonly seen in classical papillary thyroid carcinoma (cPTC). The ability to differentiate potential NIFTP/follicular variant of papillary thyroid carcinoma (FVPTC) from cPTC at the time of fine-needle aspiration (FNA) can facilitate conservative management of NIFTP. The aim of the current study was to investigate how molecular testing may add to cytologic assessment in the pre-operative differentiation of potential NIFTP/FVPTC and cPTC. We had previously evaluated cytologists' ability to prospectively distinguish potential NIFTP/FVPTC from cPTC in a cohort of 56 consecutive FNAs diagnosed as malignant or suspicious for malignancy. We utilized this cohort to perform molecular analysis. Detected molecular abnormalities were stratified into two groups: (1) those supporting malignancy and (2) those supporting a diagnosis of potential NIFTP/FVPTC. The cytologists' characterization of cases and the detected molecular alterations were correlated with the final histologic diagnoses. Molecular testing was performed in 52 (93%) of the 56 cases. For the 37 cases cytologists favored to be cPTC, 31 (84%) had a molecular result that supported malignancy (28 BRAF V600E mutations, 2 NTRK1 fusions, 1 AGK-BRAF fusion). For the 8 cases that were favored to be NIFTP/FVPTC by cytologists, 7 (88%) had a molecular result that supported conservative management (1 NRAS mutation, 6 wild-type result). Seven cases were designated as cytomorphologically indeterminate for NIFTP/FVPTC or cPTC, of which 6 (86%) had a molecular result that would have aided in the pre-operative assessment of potential NIFTP/FVPTC or cPTC/malignancy. These included 3 BRAF V600E mutations in nodules that were cPTC on resection, an HRAS mutation, and a wild-type result in the 2 nodules that were NIFTP, and a TERT promoter mutation along with an NRAS mutation in a poorly differentiated thyroid carcinoma. For nodules with an FNA diagnosis of suspicious for malignancy or malignant, cytologists can differentiate most cases of potential NIFTP/FVPTC from cPTC. However, molecular testing may be valuable for a subset of cases, especially those that are indeterminate for potential NIFTP/FVPTC versus cPTC based on cytologic features alone.

Cytologic-histologic correlation of programmed death-ligand 1 immunohistochemistry in lung carcinomas

BACKGROUND

Programmed cell death protein 1 inhibitors increasingly are being used to treat patients with advanced lung carcinomas. Programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) in tumor cells (TCs) and tumor-infiltrating immune cells (ICs) is used to select patients for programmed cell death protein 1 inhibition, but few studies have evaluated PD-L1 IHC in cytology specimens. The objective of the current study was to compare PD-L1 IHC in cytology cell blocks and matched surgical specimens.

METHODS

A total of 56 cytology specimens obtained between 2013 and 2016 with matching surgical specimens were stained with anti-PD-L1. Membranous positivity was scored as a percentage of the TCs and ICs by 2 pathologists. Results were compared between cytology and surgical specimens, and interobserver concordance was assessed.

RESULTS

The average PD-L1 positivity rate was 28% in TCs and 5% in ICs in surgical specimens (standard deviations of 37% and 7%, respectively), and 21% in TCs and 8% in ICs in cytology specimens (standard deviations of 33% and 15%, respectively). Interobserver concordance was high for TCs in surgical and cytology specimens (intraclass correlation coefficients of 0.96 and 0.96, respectively), and was moderate for ICs in surgical and cytology specimens (intraclass correlation coefficients of 0.47 and 0.67, respectively). There was moderate to high correlation between PD-L1 positivity in TCs between surgical and cytology specimens (Spearman correlation coefficient [Spearman r], 0.69), particularly among fine-needle aspiration specimens (Spearman r, 0.78), but not between PD-L1 positivity in ICs in surgical and cytology specimens (Spearman r, 0.14), including among fine-needle aspiration specimens (Spearman r, 0.23).

CONCLUSIONS

Tumor PD-L1 IHC positivity in cytology specimens appears to correlate strongly with results obtained from matching surgical specimens. PD-L1 IHC in ICs within cytology specimens does not reflect results in matched surgical specimens and should not be used in clinical decision making. Cancer Cytopathol 2018;126:253-63. © 2018 American Cancer Society.

Immunohistochemistry of Pulmonary Biomarkers: A Perspective From Members of the Pulmonary Pathology Society

The use of immunohistochemistry for the determination of pulmonary carcinoma biomarkers is a well-established and powerful technique. Immunohistochemisty is readily available in pathology laboratories, is relatively easy to perform and assess, can provide clinically meaningful results very quickly, and is relatively inexpensive. Pulmonary predictive biomarkers provide results essential for timely and accurate therapeutic decision making; for patients with metastatic non-small cell lung cancer, predictive immunohistochemistry includes ALK and programmed death ligand-1 (PD-L1) (ROS1, EGFR in Europe) testing. Handling along proper methodologic lines is needed to ensure patients receive the most accurate and representative test outcomes.

Rapid On-Site Evaluation of Endobronchial Ultrasound–Guided Transbronchial Needle Aspirations for the Diagnosis of Lung Cancer: A Perspective From Members of the Pulmonary Pathology Society

Context.—

Endobronchial ultrasound–guided transbronchial needle aspiration (EBUS-TBNA) has emerged as a very useful tool in the field of diagnostic respiratory cytology. Rapid on-site evaluation (ROSE) of EBUS-TBNA not only has the potential to improve diagnostic yield of the procedure but also to triage samples for predictive molecular testing to guide personalized treatments for lung cancer.

Objective.—

To provide an overview of the current status of the literature regarding ROSE of EBUS-TBNA in the diagnosis of lung cancer.

Data Sources.—

An electronic literature search in PubMed and Google databases was performed using the following key words: cytology, lung cancer, on-site evaluation, rapid on-site evaluation, and ROSE EBUS-TBNA. Only articles published in English were included in this review.

Conclusions.—

Rapid on-site evaluation can ensure that the targeted lesion is being sampled and can enable appropriate specimen triage. If available, it should be used with EBUS-TBNA in the diagnosis of lung cancer because it can minimize repeat procedures for additional desired testing (ie, molecular studies). Some studies have shown that ROSE does not adversely affect the number of aspirations, total procedure time of EBUS-TBNA, or the rate of postprocedure complications; it is also helpful in providing a preliminary diagnosis that can reduce the number of additional invasive procedures, such as mediastinoscopy. As EBUS technology continues to evolve, our knowledge of the role of ROSE in EBUS-TBNA for the diagnosis of lung cancer will also continue to grow and evolve.

Molecular testing of different cytologic preparations in patients with advanced lung adenocarcinoma: which yields the best results?

INTRODUCTION

This study constitutes the first systematic comparison of molecular results between different cytology preparations in patients with lung adenocarcinoma undergoing testing for EGFR, KRAS, and BRAF mutations.

MATERIALS AND METHODS

115 archival cytology preparations (direct smears, ThinPrep preparations [TP], and cell blocks [CB]) from lung adenocarcinomas with known EGFR, KRAS, or BRAF mutations were tested and compared with clinical testing results. Results were compared between preparations and analyzed in relation to tumor purity and tumor cell content.

RESULTS

82 (77%) of 106 informative cases were concordant with clinical testing results. There was no significant difference in the concordance rate between CB, TP, air-dried smears, or alcohol-fixed smears (P = 0.3803), nor between preparations with <25%, 25% to 50%, or >50% tumor purity (P = 0.1147). Concordance rates were lower in preparations with ≤100 tumor cells (P = 0.0002).

CONCLUSIONS

Smears, TP, and CB are all valid substrates for molecular testing. Although tumor purity did not significantly affect results, low tumor content showed poorer performance. Recording tumor purity and content is recommended.

Diagnosis of Acute Cellular Rejection and Antibody-Mediated Rejection on Lung Transplant Biopsies: A Perspective From Members of the Pulmonary Pathology Society

Context.—

The diagnosis and grading of acute cellular and antibody-mediated rejection (AMR) in lung allograft biopsies is important because rejection can lead to acute graft dysfunction and/or failure and may contribute to chronic graft failure. While acute cellular rejection is well defined histologically, no reproducible specific features of AMR are currently identified. Therefore, a combination of clinical features, serology, histopathology, and immunologic findings is suggested for the diagnosis of AMR.

Objective.—

To describe the perspective of members of the Pulmonary Pathology Society (PPS) on the workup of lung allograft transbronchial biopsy and the diagnosis of acute cellular rejection and AMR in lung transplant.

Data Sources.—

Reports by the International Society for Heart and Lung Transplantation (ISHLT), experience of members of PPS who routinely review lung allograft biopsies, and search of literature database (PubMed).

Conclusions.—

Acute cellular rejection should be assessed and graded according to the 2007 working formulation of the ISHLT. As currently no specific features are known for AMR in lung allografts, the triple test (clinical allograft dysfunction, donor-specific antibodies, pathologic findings) should be used for its diagnosis. C4d staining might be performed when morphologic, clinical, and/or serologic features suggestive of AMR are identified.

Preoperative Cytologic Diagnosis of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: A Prospective Analysis

BACKGROUND

The term noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has been proposed to replace noninvasive follicular variant of papillary thyroid carcinoma (FVPTC) in recognition of the indolent behavior of this tumor. The ability to differentiate NIFTP from classical papillary thyroid carcinoma (cPTC) by fine-needle aspiration (FNA) would facilitate conservative management for NIFTP. The aim of this study was to determine if NIFTP can be distinguished prospectively from cPTC.

METHODS

From June 2015 to January 2016, thyroid FNAs with a diagnosis of "malignant" or "suspicious for malignancy" were prospectively scored for features associated with NIFTP/FVPTC (microfollicular architecture) or cPTC (papillae, psammomatous calcifications, sheet-like architecture, and nuclear pseudoinclusions) and categorized as NIFTP/FVPTC, cPTC, or indeterminate. Results were correlated with subsequent histologic diagnoses.

RESULTS

The study included 52 patients with 56 resected nodules with a cytologic diagnosis of "malignant" (43/56) or "suspicious for malignancy" (13/56). Forty-nine patients (94%) underwent initial total thyroidectomy. Histopathologic diagnoses included 42 cPTC, 8 NIFTP, 3 invasive FVPTC, 2 follicular adenomas, and 1 poorly differentiated carcinoma. Excluding 7 indeterminate cases, 89% (8/9) of nodules classified as NIFTP/FVPTC on FNA demonstrated follicular-patterned lesions on histology (5 NIFTP, 1 invasive FVPTC, 2 follicular adenomas). Cytopathologists prospectively identified cPTC in 95% (38/40) of cases.

CONCLUSIONS

In thyroid FNAs with cytologic features concerning for PTC, NIFTP/FVPTC can be distinguished from cPTC in most cases by assessing a limited number of features. Therefore, it is both feasible and appropriate to attempt to separate NIFTP/FVPTC from cPTC on FNA to promote appropriate clinical management.

Liquid Biopsy in Lung Cancer: A Perspective From Members of the Pulmonary Pathology Society

Liquid biopsy has received extensive media coverage and has been called the holy grail of cancer detection. Attempts at circulating tumor cell and genetic material capture have been progressing for several years, and recent financially and technically feasible improvements of cell capture devices, plasma isolation techniques, and highly sensitive polymerase chain reaction- and sequencing-based methods have advanced the possibility of liquid biopsy of solid tumors. Although practical use of circulating RNA-based testing has been hindered by the need to fractionate blood to enrich for RNAs, the detection of circulating tumor cells has profited from advances in cell capture technology. In fact, the US Food and Drug Administration has approved one circulating tumor cell selection platform, the CellSearch System. Although the use of liquid biopsy in a patient population with a genomically defined solid tumor may potentially be clinically useful, it currently does not supersede conventional pretreatment tissue diagnosis of lung cancer. Liquid biopsy has not been validated for lung cancer diagnosis, and its lower sensitivity could lead to significant diagnostic delay if liquid biopsy were to be used in lieu of tissue biopsy. Ultimately, notwithstanding the enthusiasm encompassing liquid biopsy, its clinical utility remains unproven.

Biomarker Testing in Lung Carcinoma Cytology Specimens: A Perspective From Members of the Pulmonary Pathology Society

The advent of targeted therapy in lung cancer has heralded a paradigm shift in the practice of cytopathology with the need for accurately subtyping lung carcinoma, as well as providing adequate material for molecular studies, to help guide clinical and therapeutic decisions. The variety and versatility of cytologic-specimen preparations offer significant advantages to molecular testing; however, they frequently remain underused. Therefore, evaluating the utility and adequacy of cytologic specimens is critical, not only from a lung cancer diagnosis standpoint but also for the myriad ancillary studies that are necessary to provide appropriate clinical management. A large fraction of lung cancers are diagnosed by aspiration or exfoliative cytology specimens, and thus, optimizing strategies to triage and best use the tissue for diagnosis and biomarker studies forms a critical component of lung cancer management. This review focuses on the opportunities and challenges of using cytologic specimens for molecular diagnosis of lung cancer and the role of cytopathology in the molecular era.

KRAS and NKX2-1 Mutations in Invasive Mucinous Adenocarcinoma of the Lung

INTRODUCTION

Mucinous differentiation is observed in a subset of lung adenocarcinomas with unique clinical and pathological features, but the biology of these neoplasms is poorly understood.

METHODS

We apply targeted next-generation sequencing to characterize the mutational profiles of 21 invasive mucinous adenocarcinomas, mixed mucinous/nonmucinous adenocarcinomas, and adenocarcinomas with mucinous features of the lung and validate key findings on 954 additional lung adenocarcinomas from our institution and 514 lung adenocarcinomas from The Cancer Genome Atlas.

RESULTS

Sequencing identifies pathogenic mutations in the oncogenes Kirsten rat sarcoma viral oncogene homolog (KRAS), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), erb-b2 receptor tyrosine kinase 2 (ERBB2), and anaplastic lymphoma receptor tyrosine kinase (ALK) and recurrent mutations in tumor protein p53 (TP53), serine/threonine kinase 11 (STK11), NK2 homeobox 1 (NKX2-1), and SET domain containing 2 (SETD2). In the combined discovery and validation cohorts, we identify nine neoplasms with distinct molecular and pathological features. All are invasive mucinous adenocarcinomas or mixed mucinous/nonmucinous adenocarcinomas with mutations of KRAS and frameshift or nonsense mutations of NKX2-1. Immunohistochemical analysis shows that these neoplasms are associated with altered differentiation states, including loss of expression of the pulmonary marker thyroid transcription factor 1 (also called Nkx2.1) and expression of gastrointestinal markers.

CONCLUSIONS

These findings describe recurrent NKX2-1 mutations in invasive mucinous adenocarcinomas of the lung and support NKX2-1 as a lineage-specific tumor suppressor gene in lung carcinogenesis.

Risk stratification of follicular variant of papillary thyroid carcinoma

BACKGROUND

Recent studies have described an encapsulated and an infiltrative form of follicular variant of papillary thyroid carcinoma (FVPTC). While encapsulated tumors have been reported to have virtually no metastatic potential or recurrence risk if angioinvasion and capsular penetration are absent, infiltrative tumors have been found to have a significant metastatic potential and a risk of recurrence. In our experience, a substantial number of FVPTCs are neither fully encapsulated nor infiltrative, but instead are partially-encapsulated (PE) or well-circumscribed (WC). Thus, the aim of this study was to investigate the metastatic potential and recurrence risk of PE/WC FVPTCs in comparison with that of encapsulated and infiltrative tumors.

METHODS

We studied 77 FVPTCs resected between 2000 and 2002 and characterized the tumors as encapsulated, PE/WC, or infiltrative. Histologic assessment was then correlated with lymph node status and clinical outcome.

RESULTS

In our cohort, 27 (35%) tumors were encapsulated, 35 (45%) were PE/WC, and 15 (19%) were infiltrative. Lymph node status was similar between PE/WC and encapsulated tumors, but was significantly different between encapsulated and infiltrative groups (p<0.001), and PE/WC and infiltrative groups (p<0.001). Lymph node metastases were absent in all 15 cases of encapsulated tumors and all 9 cases of PE/WC tumors with sampled lymph nodes, but were present in 7 of 9 (78%) cases of infiltrative tumors with sampled lymph nodes. For patients with available clinical follow-up (66 cases, 86%), the median follow-up time was 111 months. No patients with encapsulated tumors recurred, one (3%) patient with a PE/WC tumor had recurrent/residual disease, and two (15%) patients with infiltrative tumors had recurrent/residual disease. The one patient with a PE/WC tumor who had recurrent/residual disease had a tumor bed recurrence 7 years after initial resection. Significantly, this was the only patient in the PE/WC group that had a positive resection margin.

CONCLUSIONS

Our results demonstrate that PE/WC FVPTCs have a very low metastatic potential/recurrence risk, indicating that they should be distinguished from more aggressive infiltrative FVPTCs.

Overexpression of CRABPI in suprabasal keratinocytes enhances the proliferation of epidermal basal keratinocytes in mouse skin topically treated with all-trans retinoic acid

We investigated whether ectopic expression of CRABPI, a cellular retinoic acid binding protein, influenced the actions of all-trans retinoic acid (ATRA) in transgenic (TG) mice. We targeted CRABPI to the basal vs. suprabasal layers of mouse epidermis by using the keratin 14 (K14) and keratin 10 (K10) promoters, respectively. Greater CRABPI protein levels were detected in the epidermis of adult transgenic(+) mice than in transgenic(-) mice for both transgenes. In adult mouse skin CRABPI overexpression in the basal or suprabasal keratinocytes did not cause morphological abnormalities, but did result in decreased CRABPII mRNA levels. Ectopically overexpressed CRABPI in suprabasal keratinocytes, but not in basal keratinocytes, enhanced the thickening of the epidermis induced by topical ATRA treatments (10 microM, 400 microl for 4 days) by 1.59+/-0.2-fold (p<0.05). ATRA treatment (10 microM) resulted in a 59.9+/-9.8% increase (p<0.05) in the BrdU labeling index in K10/FLAG-CRABPI TG(+) mice vs. TG(-) mice. Retinoid topical treatments reduced p27 and CYP26A1 mRNA levels in TG(+) and TG(-) mouse skin in K14 and K10/FLAG-CRABPI transgenic mice. As epidermal basal keratinocyte proliferation is stimulated by paracrine growth factors secreted by ATRA activated suprabasal keratinocytes, our results indicate that CRABPI overexpression in suprabasal keratinocytes enhances the physiological functions of ATRA.