A clinicopathologic and molecular analysis of five cases of bronchiolar adenoma with rare mutations.

Bronchiolar adenoma (BA) is a rare benign lung tumor that shows proliferation of bland bronchiolar-type epithelium containing a continuous layer of basal cells. This tumor entity has been newly added to the recent World Health Organization (WHO) classification 5th edition. This entity encompasses a spectrum of lesions: the classic ciliated muconodular papillary tumor (CMPT) and the non-classic CMPT. Although BA is reported to have driver mutations including BRAF V600E, EGFR, and KRAS, the molecular profile of BA is still incompletely understood. Five resected BAs at our institutions were analyzed. The BA lesions were subdivided into two groups: three proximal-type BAs and two distal-type BAs. NRAS codon 12/13 mutation and EML4 exon 20-ALK exon 20 fusion were found in two of the three proximal-types. BRAF V600E mutation was found in one of the two distal-types. Two cases coexisted with lung adenocarcinoma, with EGFR exon 19 deletion and KRAS mutation, respectively. No recurrence was observed at a median of 12 months (range 2-84 months) of follow-up. BA has uncommon variants of mutation seen in lung adenocarcinoma. NRAS mutation and ALK fusion partner has not been reported previously. The present cases may reinforce the distinctive biology of BA from lung adenocarcinoma.

Characterization of Peribiliary Gland-Constituting Cells Based on Differential Expression of Trophoblast Cell Surface Protein 2 in Biliary Tract.

Peribiliary glands (PBGs) are accessory glands with mucinous and serous acini in the biliary tree. The PBG is composed of a heterogeneous cell population, such as mucus- and pancreatic enzyme-producing epithelial cells, whereas it constitutes niches for multipotential stem/progenitor cells in the human extrahepatic bile duct (EHBD). By contrast, the nature of PBGs in the mouse EHBD remains unclear. Our aim was to establish a method for isolating and characterizing PBG-constituting cells in the mouse EHBD. We found that trophoblast cell surface protein 2 (Trop2) was expressed in the luminal epithelium of mouse EHBD exclusively, but not in the PBG. On the basis of the differential expression profile of Trop2, lumen-forming biliary epithelial cells (LBECs) and PBG-constituting epithelial cells (PBECs) were separately isolated for further characterization. Gene expression analysis revealed that the isolated mouse PBECs expressed several marker genes related to human PBGs. In the colony formation assay, PBECs showed significantly higher colony formation capacity than LBECs. In the organoid formation assay, PBECs formed cystic organoid with LBEC-like phenotype. Interestingly, PBECs proliferated, accompanied by reexpression of Trop2 in vivo after bile duct ligation. Furthermore, the unique expression profile of Trop2 was conserved in human EHBD. Our findings indicate that Trop2 is a useful marker in investigating the pathophysiological roles and characteristics of mouse and human PBGs in biliary diseases.

Oncostatin M causes liver fibrosis by regulating cooperation between hepatic stellate cells and macrophages in mice.

Fibrosis is an important wound-healing process in injured tissues, but excessive fibrosis is often observed in patients with chronic inflammation. Although oncostatin M (OSM) has been reported to play crucial roles for recovery from acute liver injury by inducing tissue inhibitor of metalloproteinase 1 (Timp1) expression, the role of OSM in chronic liver injury (CLI) is yet to be elucidated. Here, we show that OSM exerts powerful fibrogenic activity by regulating macrophage activation during CLI. Genetic ablation of the OSM gene alleviated fibrosis in a mouse model of chronic hepatitis. Conversely, continuous expression of OSM in a normal mouse liver by hydrodynamic tail vein injection (HTVi) induced severe fibrosis without necrotic damage of hepatocytes, indicating that OSM is involved in the fundamental process of liver fibrosis (LF) after hepatitis. In a primary coculture of hepatic stellate cells (HSCs) and hepatic macrophages (HMs), OSM up-regulated the expression of fibrogenic factors, such as transforming growth factor-ß and platelet-derived growth factor in HMs, while inducing Timp1 expression in HSCs, suggesting the synergistic roles of OSM for collagen deposition in the liver. Fluorescence-activated cell sorting analyses using OSM-HTVi and OSM knockout mice have revealed that bone-marrow-derived monocyte/macrophage are responsive to OSM for profibrotic activation. Furthermore, depletion or blocking of HMs by administration of clodronate liposome or chemokine inhibitor prevented OSM-induced fibrosis. CONCLUSION: OSM plays a crucial role in LF by coordinating the phenotypic change of HMs and HSCs. Our data suggest that OSM is a promising therapeutic target for LF. (Hepatology 2018;67:296-312).

NK cells activated by Interleukin-4 in cooperation with Interleukin-15 exhibit distinctive characteristics.

Natural killer (NK) cells are known to be activated by Th1-type cytokines, such as IL-2, -12, or -18, and they secrete a large amount of IFN-γ that accelerates Th1-type responses. However, the roles of NK cells in Th2-type responses have remained unclear. Because IL-4 acts as an initiator of Th2-type responses, we examined the characteristics of NK cells in mice overexpressing IL-4. In this study, we report that IL-4 overexpression induces distinctive characteristics of NK cells (B220(high)/CD11b(low)/IL-18Rα(low)), which are different from mature conventional NK (cNK) cells (B220(low)/CD11b(high)/IL-18Rα(high)). IL-4 overexpression induces proliferation of tissue-resident macrophages, which contributes to NK cell proliferation via production of IL-15. These IL-4-induced NK cells (IL4-NK cells) produce higher levels of IFN-γ, IL-10, and GM-CSF, and exhibit high cytotoxicity compared with cNK cells. Furthermore, incubation of cNK cells with IL-15 and IL-4 alters their phenotype to that similar to IL4-NK cells. Finally, parasitic infection, which typically causes strong Th2-type responses, induces the development of NK cells with characteristics similar to IL4-NK cells. These IL4-NK-like cells do not develop in IL-4Rα KO mice by parasitic infection. Collectively, these results suggest a novel role of IL-4 in immune responses through the induction of the unique NK cells.

Risk Stratification According to the Prognostic Nutritional Index for Predicting Postoperative Complications After Lung Cancer Surgery.

BACKGROUND: The prognostic nutritional index (PNI), an immune nutritional marker based on serum albumin levels and total lymphocyte count, predicts postoperative complications in various types of malignancies. However, the clinical significance of the PNI for postoperative complications following lung cancer surgery is uncertain. METHODS: Patients with resected non-small cell lung cancer (n = 515) were retrospectively analyzed and the relationship between the preoperative PNI and postoperative complications was evaluated. RESULTS: Multivariate logistic regression analysis revealed that a preoperative low PNI was a significant independent predictor of postoperative complications of Clavien-Dindo Grade ≥ II (odds ratio: 1.06 per unit decrease, 95.0% confidence interval 1.01-1.11). Patients were divided into three groups according to the preoperative PNI: normal (≥ 50; n = 324), mildly low (< 50, ≥ 45; n = 134), and severely low (< 45; n = 57). The incidence of postoperative complications of Grade ≥ II and Grade ≥ III in the normal, mildly low, and severely low PNI groups was 22.2, 39.6, and 42.1% and 7.1, 16.4, and 22.8%, respectively. The incidence of postoperative complications of Grade ≥ II and Grade ≥ III was significantly higher in the mildly low and severely low PNI groups than in the normal PNI group (p < 0.001 and p < 0.001, respectively). The incidence of air leak, pneumonia, and extrapulmonary infection, but not arrhythmia, was significantly higher in the mildly low and severely low PNI groups than in the normal PNI group. CONCLUSIONS: The PNI could be a useful marker to predict the risk of postoperative complications after lung cancer surgery.

Mature resting Ly6C(high) natural killer cells can be reactivated by IL-15.

Mature NK cells are heterogeneous as to their expression levels of cell surface molecules. However, the functional differences and physiological roles of each NK-cell subset are not fully understood. In this study, we report that based on the Ly6C expression levels, mature C57BL/6 murine NK cells can be subdivided into Ly6C(low) and Ly6C(high) subsets. Ly6C(high) NK cells are in an inert state as evidenced by the production of lower levels of IFN-γ and granzyme B, and they exhibit poorer proliferative potential than Ly6C(low) NK cells. In addition, adoptive transfer experiments revealed that Ly6C(high) NK cells are derived from Ly6C(low) NK cells in the steady state. These results strongly suggest that Ly6C(high) NK cells are resting cells in the steady state. However, in vitro, Ly6C(high) NK cells become Ly6C(low) NK cells with strong effector functions upon stimulation with IL-15. Moreover, Ly6C(high) NK cells also revert to Ly6C(low) NK cells in vivo upon injection of the IL-15 inducers polyI:C and CpG. Taken together, these results demonstrate the plasticity of mature NK cells and suggest that Ly6C(high) NK cells are a reservoir of potential NK cells that allow effective and strong response to infections.

Only surgical resection can identify the second primary lung cancer out of the metastasis after gastric cancer surgery.

OBJECTIVE: Solitary pulmonary lesions (SPLs) in patients with a history of malignancy require not only the distinction between benign and malignant, but also that between metastatic and primary lesions. We aim to establish the clinical strategy for the treatment of a solitary pulmonary lesion that is detected during the postoperative surveillance for gastric cancer. METHODS: We retrospectively examined the clinical records of the patients who underwent curative resection for gastric cancer between January 1999 and December 2009. Patients who were diagnosed with solitary pulmonary lesion during the postoperative surveillance underwent pulmonary resection, and were reviewed with regard to their histological diagnosis and prognosis. RESULTS: Out of a total of 1017 patients who underwent gastric resections during this period, 13 patients with solitary pulmonary lesion underwent pulmonary resection. These tumors were shown to be eight primary lung cancers, four metastatic tumors (three from gastric cancer) and one benign nodule. Of the eight patients with primary lung cancer, seven remained alive after pulmonary resection, including one liver metastasis case, and the other died without recurrence. In contrast, the other three patients with metastasis from gastric cancer died with distant metastasis, despite undergoing curative pulmonary resection. One of these three metastatic patients was misdiagnosed as primary lung cancer by transbronchial biopsy before surgery. CONCLUSIONS: Solitary pulmonary lesions detected during postoperative gastric cancer surveillance should undergo surgical resection to distinguish between primary and metastatic disease because of the quite different prognosis of these two entities.

Retention in the Golgi apparatus and expression on the cell surface of Cfr/Esl-1/Glg-1/MG-160 are regulated by two distinct mechanisms.

Cfr (cysteine-rich fibroblast growth factor receptor) is an Fgf (fibroblast growth factor)-binding protein without a tyrosine kinase. We have shown previously that Cfr is involved in Fgf18 signalling via Fgf receptor 3c. However, as Cfr is also known as Glg (Golgi apparatus protein)-1 or MG-160 and occurs in the Golgi apparatus, it remains unknown how the distribution of Cfr is regulated. In the present study, we performed a mutagenic analysis of Cfr to show that two distinct regions contribute to its distribution and stability. First, the C-terminal region retains Cfr in the Golgi apparatus. Secondly, the Cfr repeats in the extracellular juxtamembrane region destabilizes Cfr passed through the Golgi apparatus. This destabilization does not depend on the cleavage and secretion of the extracellular domain of Cfr. Furthermore, we found that Cfr with a GPI (glycosylphosphatidylinositol) anchor was predominantly expressed on the cell surface in Ba/F3 cells and affected Fgf18 signalling in a similar manner to the full-length Cfr, indicating that the interaction of Cfr with Fgfs on the cell surface is important for its function in Fgf signalling. These results suggest that the expression of Cfr in the Golgi apparatus and on the plasma membrane is finely tuned through two distinct mechanisms for exhibiting different functions.

Gastric Myeloid Sarcoma Mimicking a Scirrhous Gastric Cancer.

Myeloid sarcoma (MS) is a relatively rare manifestation of myeloid neoplasms at sites other than the bone marrow. The rarity of gastrointestinal (GI) MS is attributed to certain factors, such as misdetection due to insufficient endoscopic assessments at the initial presentation with acute myeloid leukemia (AML) as well as the difficulty of making a histologic assessment of leukemic involvement of the GI tract. We herein report a case of AML with gastric involvement and discuss the importance of screening examinations and therapies considering the location of MS and the data of cytogenetic and molecular mutation.

TTF-1 and c-MYC-defined Phenotypes of Large Cell Neuroendocrine Carcinoma and Delta-like Protein 3 Expression for Treatment Selection.

The standard treatment regimen has not yet been established for advanced pulmonary large cell neuroendocrine carcinoma (LCNEC) because of its rarity. LCNEC can be subdivided into 2 mutually exclusive molecular subgroups: STK11/KEAP1 and TP53 mutated with high neuroendocrine expression and transcriptional profile of ASCL1high/DLL3high/NOTCHlow (non-small cell lung carcinoma, NSCLC-like) or RB1 and TP53 mutated with reduced neuroendocrine markers and transcriptional pattern of ASCL1low/DLL3low/NOTCHhigh (small cell lung cancer, SCLC-like). Model-based clustering shows that SCLC has subdivided into 2 major proteomic subsets defined by either TTF-1high/c-MYClow or TTF-1low/c-MYChigh, which may correspond to 2 mutually exclusive molecular subgroups: NSCLC-like or SCLC-like, respectively. We herein investigated whether TTF-1 and c-MYC could be applied to LCNEC to identify distinct subsets immunohistochemically and assessed DLL3 expression in these subsets. The protein expression profile may be useful to select patients for potential efficacy of targeted therapies including aurora kinase inhibitors for MYC alterations or anti-DLL3 antibody-drug conjugates. TTF-1 and c-MYC expression was mutually exclusive in 25 of 27 (93%) cases; TTF-1+/c-MYC- in 10, TTF-1-/c-MYC+ in 15, and TTF-1+/c-MYC+ in 2. DLL3 expression was seen in 15 of 27 cases (56%). All 12 TTF-1+ LCNEC cases were positive for DLL3. Three of 15 (20%) TTF-1-/c-MYC+ cases showed DLL3 positivity. LCNEC could be separated into 2 subsets proteomically defined by TTF-1 and c-MYC expression, which may be suitable to guide treatment selection including aurora kinase inhibitors for c-MYC+ cases. TTF-1 positivity can serve as a surrogate marker for DLL3, but caution is necessary as 20% of TTF-1- cases showed DLL3 positivity.

Omental Flap for Bronchopleural Fistula After Pneumonectomy and Aorta Replacement.

Bronchopleural fistula (BPF) is a fatal complication after lung cancer surgery. We report the case of a 56-year-old man treated with omental flap for BPF after pneumonectomy along with descending aorta replacement. He underwent left pneumonectomy with combined resection of the descending aorta, followed by replacement with prosthetic graft after the diagnosis of lung cancer, cT4 N1 M0 stage IIIA. He had BPF postoperatively and underwent an omental flap plombage after unsuccessful repair using the latissimus dorsi muscle. He did not have BPF recurrence or aortic graft infection. An omental flap is a useful option for treating BPF with an intrathoracic prosthetic graft.

Histology and Mechanics of In Vivo Tissue-Engineered Vascular Graft for Children.

PURPOSE: This study sought to evaluate the histologic and mechanical properties of autologous in vivo tissue-engineered vascular grafts (in vivo TEVGs) used for pediatric heart surgery. DESCRIPTION: Molds of in vivo TEVGs made of silicone drain tubes were embedded into subcutaneous spaces in 2 boys during their first operation and were used as patch materials to treat pulmonary artery stenosis during the second operation. The remaining pieces of the patches were evaluated histologically and mechanically. EVALUATION: In vivo TEVGs had very smooth luminal surfaces, and their walls mainly comprised collagen fibers and small numbers of fibroblasts. Mean wall thickness was 200 µm, mean suture retention strength was 2.26 N, and burst pressure was 3057 mm Hg. CONCLUSIONS: Human in vivo TEVGs mainly comprise collagen fibers, and their mechanical properties prove them safe for pulmonary arterioplasty. Therefore, human in vivo TEVGs may be promising alternatives to autologous pericardium for pediatric cardiovascular surgical procedures that often require multistage operations.

Prognostic significance of spread through air spaces in pulmonary metastases from colorectal cancer.

OBJECTIVES: Surgical resection for pulmonary metastases from colorectal cancer could provide long-term survival in selected patients, and it is commonly performed in practice. However, surgical margin relapse sometimes occurs and is a problematic issue to resolve. Spread through air spaces (STAS) is one of the invasion forms in primary lung cancer and is associated with local recurrence and a poor prognosis. The aim of this study was to evaluate the prognostic significance of STAS for pulmonary metastases from colorectal cancer and to assess the predictability of STAS with preoperative clinical information. METHODS: A total of 96 pulmonary metastatic lesions from colorectal cancer in 37 patients who underwent metastasectomy at our institution from January 2008 to December 2013 were retrospectively analyzed. RESULTS: STAS was identified in 41.6 % of the 96 lesions. Surgical margin relapse was found in 8 lesions (8.3 %) from 7 patients (18.9 %). The distance of STAS was identified as an independent risk factor for surgical margin relapse on multivariable analysis (p =  0.033). The patients with STAS showed significantly worse overall survival than those without (5-year overall survival rate: 30.3 % vs. 76.9 %; p =  0.002). On multivariable analysis, patients with STAS had a significantly higher risk of death than those without (p =  0.019). An elevated pre-metastasectomy serum carcinoembryonic antigen level was independently correlated with STAS on multivariable analysis (p =  0.049). CONCLUSION: STAS was related to a poor prognosis and surgical margin relapse in pulmonary metastases from colorectal cancer.

Autoimmune hepatitis during preoperative chemotherapy in a patient with thymoma.

Autoimmune diseases associated with thymoma are well known, with myasthenia gravis being the most common, while autoimmune hepatitis (AIH) is extremely rare. The case of a 63-year-old woman with AIH that developed during preoperative chemotherapy for invasive type B2 thymoma is presented. Liver dysfunction was improved by steroid treatment using oral prednisolone, 30 mg daily, followed by tapering. The patient underwent a macroscopic complete resection including dissemination, and no evidence of recurrence has been seen for 13 months. Although the serum levels of anti-acetylcholine receptor antibody were elevated, no symptoms of myasthenia gravis appeared during the clinical course. This is a rare case of non-myasthenic thymoma complicated with AIH. AIH should be carefully considered in thymoma patients with liver dysfunction, since multidisciplinary treatment is required for invasive thymoma.

Quantitative computed tomography for predicting cardiopulmonary complications after lobectomy for lung cancer in patients with chronic obstructive pulmonary disease.

OBJECTIVES: In lung cancer resection, chronic obstructive pulmonary disease is a risk factor for post-operative complications. Few studies on post-operative complications of lung cancer resection have considered radiographic emphysematous change as an index. Here, we have examined the relationship between the regional ratio of the emphysematous area in pre-operative computed tomography images and cardiopulmonary complications in patients with chronic obstructive pulmonary disease who underwent lung cancer resection. METHODS: We retrospectively evaluated 159 patients with chronic obstructive pulmonary disease who underwent lobectomy for lung cancer at Shizuoka Cancer Center Hospital, Shizuoka, Japan, between 2002 and 2011. Pre-operative factors, including the proportion of the emphysematous area measured by computed tomography as a percentage of the low attenuation area (LAA%), as well as intraoperative factors were analyzed. Cardiopulmonary complications, including pyothorax, pneumonia and atelectasis, acute pulmonary injury, indwelling chest tube, long duration of oxygen supply, and arrhythmia, were evaluated. RESULTS: Cardiopulmonary complications were observed among 61 patients (38%). Univariate analysis revealed that patient age, percentage of forced expiratory volume in 1 s, LAA%, and volume of blood loss were significantly associated with cardiopulmonary complications. Multivariate analysis indicated patient age and LAA% as being significant independent predictors of cardiopulmonary complications. CONCLUSIONS: The regional ratio of the emphysematous area is useful for predicting cardiopulmonary complications in patients with chronic obstructive pulmonary disease who undergo lobectomy for lung cancer. In such patients who are also ≥ 70 years of age and exhibit LAA% ≥ 1.0%, careful intra- and post-operative management is warranted.

Solitary peribronchiolar metaplasia showing a sub-solid nodule on computed tomography.

Recent advances in radiographic imaging and thoracic surgery have facilitated surgery for small lung tumors by eliminating the need for pathological diagnosis. To date, we have experienced two cases of small lung tumors that were surgically resected without pathological diagnosis as malignant. Computed tomography (CT) revealed sub-solid nodules in the peripheral lung. After tumor resection, both tumors were pathologically diagnosed as peribronchiolar metaplasia. To the best of our knowledge, solitary peribronchiolar metaplasia showing a sub-solid nodule on CT imaging has not previously been reported.

Inhibitory effects of parthenolide on antigen-induced microtubule formation and degranulation in mast cells.

Pharmacological modulation of IgE-mediated mast cell activation is important to the development of anti-allergic reagents. In this study, we investigated the effects of parthenolide (PTL) on high-affinity IgE receptor (FcepsilonRI)-induced degranulation in mast cells. PTL dose-dependently inhibited degranulation induced by IgE.antigen stimulation in RBL-2H3 cells and BMMCs. Although PTL is a potent NF-kappaB inhibitor by targeting IkappaB kinase complex, NF-kappaB inhibition by other IkappaB kinase inhibitors did not inhibit degranulation in mast cells. IgE.antigen-induced microtubule formation is well known to be critical for degranulation in mast cells. Immunocytochemical study with anti-alpha-tubulin antibody revealed that PTL significantly inhibited IgE.antigen-induced microtubule formation. However, PTL, as well as nocodazol, had no significant effects on degranulation in the fyn-deficient BMMCs, suggesting that inhibitory effects of PTL in the microtubule formation are fyn dependent. We further demonstrated that in vivo administration of PTL in mice strongly inhibited passive cutaneous anaphylaxis reaction. The present study provides a possibility to develop potent reagents against mast cell activation based on an inhibition of microtubule formation.

Spontaneous Regression of Primary Pulmonary Synovial Sarcoma.

We report a rare case of primary pulmonary synovial sarcoma that underwent spontaneous regression after a transbronchial biopsy. A 38-year-old woman with a well-demarcated solitary mass shadow on chest roentgenogram was referred to us. A transbronchial biopsy was performed, and immunohistochemical results as well as detection of SYT-SSX1 (SYnovial sarcoma Translocation-Synovial Sarcoma X chromosome breakpoint) transcripts resulted in a diagnosis of synovial sarcoma. A right lower lobectomy was performed during video-assisted thoracoscopic surgery. Pathologic examination revealed widespread coagulative necrosis with feeding arterioles occluded by organized thrombi. To our knowledge, this is the first report of a case of spontaneous regression of primary pulmonary synovial sarcoma.

Microthymoma and microscopic thymomas associated with a thymic cyst without solid component.

A 75-year-old asymptomatic man presented with an anterior mediastinal cyst without a solid component on computed tomography. Pathologic examination of the specimens obtained by thoracoscopic resection showed a thymic cyst with a 1.6-mm type A microthymoma in the surrounding thymic tissue. In addition, there were multiple hyperplastic nodules smaller than 1 mm histologically corresponded to microscopic thymomas. The patient underwent completion thymectomy through median sternotomy; thereafter, there was no residual thymic neoplasm detected. This was the first case report of a type A microthymoma. Microthymoma or microscopic thymoma could be present concomitantly with a thymic cyst without a solid component.

Significance of PD-L1 expression in pulmonary metastases from head and neck squamous cell carcinoma.

BACKGROUND: The mechanism by which tumors escape the immune system has been actively investigated and is partly explained by the programmed death-1 (PD-1) and its ligand (PD-L1) pathway. This study is aimed at clarifying the prognostic significance of PD-L1 expression in patients with surgically resected pulmonary metastases of head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS: A retrospective review was conducted of 26 HNSCC patients who underwent complete resection of pulmonary metastases. PD-L1 expression in both the primary and metastatic tumors was evaluated using immunohistochemistry (anti-PD-L1 antibody, clone SP263). High PD-L1 expression was defined as ≥50% of tumor cells with positive staining. Survival and prognostic impacts following pulmonary metastasectomy were analyzed based on the PD-L1 expression level. RESULTS: The patients included 23 men and 3 women, with a median age of 65 years. Six (23%) of the pulmonary metastatic cases showed high PD-L1 expression, while their corresponding primary lesions had low PD-L1 expression. The 5-year overall survival rate after pulmonary metastasectomy was 57.6% in all cases. The 5-year overall survival rates were 72.5% and 16.7% in the low and high PD-L1 groups, respectively (p < 0.001). Multivariate analysis demonstrated that high PD-L1 expression and older age (>65 years) correlated independently with a shorter overall survival (p < 0.001). CONCLUSIONS: High PD-L1 expression in pulmonary metastases could be an independent predictor of poor outcome in HNSCC patients undergoing pulmonary metastasectomy. This is the first report evaluating the prognostic implication of PD-L1 expression in metastatic HNSCC.