Fluorescence In Situ Hybridization and Immunohistochemistry as Diagnostic Methods for ALK Positive Non-Small Cell Lung Cancer Patients

Background

Anaplastic Lymphoma Kinase (ALK) positivity represents a novel molecular target in a subset of Non-Small Cell Lung Cancers (NSCLC). We explore Fluorescence in situ Hybridization (FISH) and Immunohistochemistry (IHC) as diagnostic methods for ALK positive patients and to describe its prevalence and outcomes in a population of NSCLC patients.

Methods

NSCLC patients previously screened for Epidermal Growth Factor Receptor (EGFR) at our institution were selected. ALK positive patients were identified by FISH and the value of IHC (D5F3) was explored.

Results

ninety-nine patients were identified. Median age was 61.5 years (range 35–83), all were caucasians, eighty percent were adenocarcinomas, fifty-one percent were male and thirty-eight percent were current smokers. Seven (7.1%) patients were ALK positive by FISH, thirteen (13.1%) were EGFR mutant, and 65 (65.6%) were negative/Wild Type (WT) for both ALK and EGFR. ALK positivity and EGFR mutations were mutually exclusive. ALK positive patients tend to be younger than EGFR mutated or wt patients. ALK positive patients were predominantly never smokers (71.4%) and adenocarcinoma (71.4%). ALK positive and EGFR mutant patients have a better outcome than negative/WT. All patients with ALK FISH negative tumours were negative for ALK IHC. Out of 6 patients positive for ALK FISH with more tissue available, 5 were positive for ALK IHC and 1 negative.

Conclusions

ALK positive patients represent 7.1% of a population of selected NSCLC. ALK positive patients have different clinical features and a better outcome than EGFR WT and ALK negative patients. IHC is a promising method for detecting ALK positive NSCLC patients.     

Analysis of Driver Mutations in Female Non-Smoker Asian Patients with Pulmonary Adenocarcinoma

Previous studies have revealed that EGFR mutation and/or EML4?CALK gene fusion rate was higher in the non-smoker Asian females with pulmonary adenocarcinoma. The aim of this study is to determine the distribution of known oncogenic driver mutations in the female non-smoker Asian patients with pulmonary adenocarcinoma. 104 consecutively resected lung adenocarcinomas from 396 non-smoker females (less than 100 cigarettes in a lifetime) at a single institution (Tongji University, Shanghai, China) were analyzed for mutations in EGFR, EML4?ALK, KRAS, HER2, BRAF, and PIK3CA. 73 (70.2?%) tumors harbored EGFR mutations; among these, 28 were deletions in exon 19, 44 were L858R missense changes, and eight were T790M mutations. 10 (9.6?%) harbored EML4?ALK fusions, two harbored KRAS mutations, two harbored BRAF mutations, and two harbored PI3K mutations. A majority of the mutations were mutually exclusive, except two with EGFR mutation and BRAF mutation, one with EML4?ALK fusions and PI3K mutation. Thus, 82.7?% (86 of 104; 95?% CI, 75.4?C90.0?%) of lung adenocarcinomas from non-smoker females were found to harbor the well-known oncogenic mutations in five genes. Lung cancer in non-smoking Asian females is a distinct entity, with majority of this subgroup being developed by the oncogenic mutations. The prospective mutation examination in this population will be helpful for devising a targeted therapy for a majority of the patients.     

The Impact of Genomic Prof ling for Novel Cancer Therapy–Recent Progress in Non-Small Cell Lung Cancer

There is high expectation for significant improvements in cancer patient care after completion of the human genome project in 2003.Through pains-taking analyses of genomic profiles in cancer patients,a number of targetable gene alterations have been discovered,with some leading to novel therapies,such as activating mutations of EGFR,BRAF and ALK gene fusions.As a result,clinical management of cancer through targeted therapy has finally become a reality for a subset of cancers,such as lung adenocarcinomas and melanomas.In this review,we summarize how gene mutation discovery leads to new treatment strategies using non-small cell lung cancer(NSCLC)as an example.We also discuss possible future implications of cancer genome analyses.     

Chronic Obstructive Pulmonary Disease-Related Non-Small-Cell Lung Cancer Exhibits a Low Prevalence of EGFR and ALK Driver Mutations

Lung cancer and chronic obstructive pulmonary disease (COPD) are two major lung diseases. Epidermal growth factor receptor (EGFR) mutations, v‐Ki‐ras2 Kirsten rat sarcoma (KRAS) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements represent driver mutations that are frequently assessed on initial evaluation of non-small-cell lung cancer (NSCLC). The present study focused on the expression of driver mutations in NSCLC patients presenting with COPD and further evaluated the association between NSCLC and COPD. Data from 501 consecutive patients with histologically proven recurrent or metastatic NSCLC were analyzed retrospectively. The patients underwent spirometry and genotyping of EGFR, ALK, and KRAS in tissue samples. Patient characteristics and expression of driver mutations were compared between the COPD and non-COPD groups.Among 350 patients with spirometric results, 106 (30.3%) were diagnosed with COPD, 108 (30.9%) had EGFR mutations, 31 (8.9%) had KRAS mutations, and 34 (9.7%) showed ALK rearrangements. COPD was independently associated with lower prevalences of EGFR mutations (95% confidence interval [CI], 0.254–0.931, p = 0.029) and ALK rearrangements (95% CI, 0.065–0.600, p = 0.004). The proportions of EGFR mutations and ALK rearrangements decreased as the severity of airflow obstruction increased (p = 0.001). In never smokers, the prevalence of EGFR mutations was significantly lower in the COPD group than in the non-COPD group (12.7% vs. 49.0%, p = 0.002). COPD-related NSCLC patients exhibited low prevalences of EGFR mutations and ALK rearrangements compared with the non-COPD group. Further studies are required regarding the molecular mechanisms underlying lung cancer associated with COPD.     

High-content analysis of cancer genome DNA alterations

New technologies as well as concerted brute-force approaches have increased the content (number of genes) that can be characterized for genomic DNA alterations. Recent advances include the detection of activating point mutations in key kinase genes (BRAF, EGFR, and PIK3CA) in multiple cancer types: preliminary insight into the entire repertoire of genes that can be mutated in cancer; the discovery of new oncogenes by high-resolution profiling of DNA copy number alterations; and the bioinformatic-driven discovery of oncogenic gene fusions. High-content promoter methylation detection systems have been used to discover additional methylated genes and have provided evidence for a stem cell origin for certain tumors. Some of these advances have had significant impact on the development and clinical testing of new therapeutics.     

EML4-ALK 融合基因在非小细胞肺癌中的研究进展

肺癌是发病率和死亡率最高的恶性肿瘤,分子靶向治疗以其特异性高、副反应轻的特点正日益受到关注。近年来临床研究发现EML4-ALK融合基因是除EGFR突变及KRAS突变之外的另-个重要的酪氨酸激酶抑制剂的作用靶点,该融合基因在年轻、不吸烟或少吸烟、腺癌、无EGFR和KRAS突变的非小细胞肺癌患者中发生率较高,且该融合基因阳性者对酪氨酸激酶抑制剂耐药,对于ALK抑制剂(如克唑替尼)则有良好的治疗反应,关于该药的临床试验表明:总有效率达57%(46例确定为部分缓解,1例确定为完全缓解),估计6个月无进展生存概率为72%,常见的副反应是1、2级胃肠道反应。该基因及该药的发现为非小细胞肺癌患者带来了希望。     

Ras Effector Mutant Expression Suggest a Negative Regulator Inhibits Lung Tumor Formation

Lung cancer is currently the most deadly malignancy in industrialized countries and accounts for 18% of all cancer-related deaths worldwide. Over 70% of patients with non-small cell lung cancer (NSCLC) are diagnosed at a late stage, with a 5-year survival below 10%. KRAS and the EGFR are frequently mutated in NSCLC and while targeted therapies for patients with EGFR mutations exist, oncogenic KRAS is thus far not druggable. KRAS activates multiple signalling pathways, including the PI3K/Akt pathway, the Raf-Mek-Erk pathway and the RalGDS/Ral pathway. Lung-specific expression of BrafV600E, the most prevalent BRAF mutation found in human tumors, results in Raf-Mek-Erk pathway activation and in the formation of benign adenomas that undergo widespread senescence in a Cre-activated Braf mouse model (Braf^CA). However, oncogenic KRAS expression in mice induces adenocarcinomas, suggesting additional KRAS-activated pathways cooperate with sustained RAF-MEK-ERK signalling to bypass the oncogene-induced senescence proliferation arrest.To determine which KRAS effectors were responsible for tumor progression, we created four effector domain mutants (S35, G37, E38 and C40) in G12V-activated KRAS and expressed these alone or with BrafV600E in mouse lungs… The S35 and E38 mutants bind to Raf proteins but not PI3K or RalGDS; the G37 mutant binds to RalGDS and not Raf or PI3K and the C40 mutant is specific to PI3K. We designed lentiviral vectors to code for Cre recombinase along with KRAS mutants (V12, V12/S35, V12/G37, V12/E38 or V12/C40) or EGFP as a negative control.. These lentiviruses were used to infect Braf^CA and wild-type mice. Surprisingly there was a significant decrease in tumor number and penetrance with each KRAS effector domain mutant relative to controls, suggesting that KRAS directly activates effectors with tumor suppressive functions.     

非小细胞肺癌分子靶向药物治疗的研究进展

非小细胞肺癌(NSCLC)为最常见的肺癌病理类型,约占肺癌总数的 85%。大多数肺癌患者在确诊时已属晚期,失去手术机会, 保守治疗成为其重要治疗手段,但晚期肺癌患者的预后仍不理想。近年来,分子靶向治疗在肿瘤治疗领域取得重要进展,亦有研究显示 其在 NSCLC 的临床实践中发挥显著疗效。除表皮生长因子受体(EGFR)和间变淋巴瘤激酶(ALK)等主要基因突变之外,血管内皮生 长因子(VEGF)、ROS1、c-MET、RET、K-RAS、BRAF 也是目前 NSCLC 分子靶向治疗的相关靶点。综述 NSCLC 分子靶向药物治疗 的研究进展,旨在为该疾病的治疗提供参考。     

PD-L1 and Tumor Infiltrating Lymphocytes as Prognostic Markers in Resected NSCLC

IntroductionImmune checkpoint inhibition has shifted treatment paradigms in non-small cell lung cancer (NSCLC). Conflicting results have been reported regarding the immune infiltrate and programmed death-ligand 1 (PD-L1) as a prognostic marker. We correlated the immune infiltrate and PD-L1 expression with clinicopathologic characteristics in a cohort of resected NSCLC.MethodsA tissue microarray was constructed using triplicate cores from consecutive resected NSCLC. Immunohistochemistry was performed for CD8, FOXP3 and PD-L1. Strong PD-L1 expression was predefined as greater than 50% tumor cell positivity. Matched nodal samples were assessed for concordance of PD-L1 expression.ResultsOf 522 patients, 346 were node-negative (N0), 72 N1 and 109 N2; 265 were adenocarcinomas (AC), 182 squamous cell cancers (SCC) and 75 other. Strong PD-L1 expression was found in 24% cases. In the overall cohort, PD-L1 expression was not associated with survival. In patients with N2 disease, strong PD-L1 expression was associated with significantly improved disease-free (DFS) and overall survival (OS) in multivariate analysis (HR 0.49, 95%CI 0.36–0.94, p = 0.031; HR 0.46, 95%CI 0.26–0.80, p = 0.006). In this resected cohort only 5% harboured EGFR mutations, whereas 19% harboured KRAS and 23% other. KRAS mutated tumors were more likely to highly express PD-L1 compared to EGFR (22% vs 3%). A stromal CD8 infiltrate was associated with significantly improved DFS in SCC (HR 0.70, 95%CI 0.50–0.97, p = 0.034), but not AC, whereas FOXP3 was not prognostic. Matched nodal specimens (N = 53) were highly concordant for PD-L1 expression (89%).ConclusionPD-L1 expression was not prognostic in the overall cohort. PD-L1 expression in primary tumor and matched nodal specimens were highly concordant. The observed survival benefit in N2 disease requires confirmation.     

Trametinib with or without Vemurafenib in BRAF Mutated Non-Small Cell Lung Cancer

V-Raf Murine Sarcoma Viral Oncogene Homolog B (BRAF) mutated lung cancer is relatively aggressive and is resistant to currently available therapies. In a recent phase II study for patients with BRAF-V600E non-small cell lung cancer (NSCLC), BRAF V600E inhibitor demonstrated evidence of activity, but 30% of this selected group progressed while on treatment, suggesting a need for developing alternative strategies. We tested two different options to enhance the efficacy of vemurafenib (BRAF V600E inhibitor) in BRAF mutated NSCLC. The first option was the addition of erlotinib to vemurafenib to see whether the combination provided synergy. The second was to induce MEK inhibition (downstream of RAF) with trametinib (MEK inhibitor). We found that the combination of vemurafenib and erlotinib was not synergistic to the inhibition of p-ERK signaling in BRAF-V600E cells. Vemurafenib caused significant apoptosis, G1 arrest and upregulation of BIM in BRAF-V600 cells. Trametinib was effective as a single agent in BRAF mutated cells, either V600E or non-V600E. Finally, the combination of vemurafenib and trametinib caused a small but significant increase in apoptosis as well as a significant upregulation of BIM when compared to either single agent. Thus, hinting at the possibility of utilizing a combinational approach for the management of this group of patients. Importantly, trametinib alone caused upregulation of p-AKT in BRAF non-V600 mutated cells, while this effect was nullified with the combination. This finding suggests that, the combination of a MEK inhibitor with a BRAF inhibitor will be more efficacious in the clinical setting for patients with BRAF mutated NSCLC.     

The Molecular Detection and Clinical Significance of ALK Rearrangement in Selected Advanced Non-Small Cell Lung Cancer: ALK Expression Provides Insights into ALK Targeted Therapy

Background

This study aimed to elucidate clinical significance of anaplastic lymphoma kinase (ALK) rearrangement in selected advanced non-small cell lung cancer (NSCLC), to compare the application of different ALK detection methods, and especially evaluate a possible association between ALK expression and clinical outcomes in crizotinib-treated patients.

Methods

ALK status was assessed by fluorescent in situ hybridization (FISH), immunohistochemistry (IHC) and quantitative RT-PCR (qRT-PCR) in 173 selected advanced NSCLC patients. Clinicopathologic data, genotype status and survival outcomes were analyzed. Moreover, the association of ALK expression with clinical outcomes was evaluated in ALK FISH-positive crizotinib-treated patients including two patients with concurrent epidermal growth factor receptor (EGFR) mutation.

Results

The positivity detection rate of ALK rearrangement by FISH, IHC and qRT-PCR was 35.5% (59/166), 35.7% (61/171), and 27.9% (34/122), respectively. ALK rearrangement was observed predominantly in young patients, never or light smokers, and adenocarcinomas, especially with signet ring cell features and poor differentiation. Median progression-free survival (PFS) of crizotinib-treated patients was 7.6 months. The overall survival (OS) of these patients was longer compared with that of crizotinib-naive or wild-type cohorts, but there was no significant difference in OS compared with patients with EGFR mutation. ALK expression did not associate with PFS; but, when ALK expression was analyzed as a dichotomous variable, moderate and strong ALK expression had a decreased risk of death (P = 0.026). The two patients with concomitant EGFR and ALK alterations showed difference in ALK expression, response to EGFR and ALK inhibitors, and overall survival.

Conclusions

Selective enrichment according to clinicopathologic features in NSCLC patients could highly improve the positivity detection rate of ALK rearrangement for ALK-targeted therapy. IHC could provide more clues for clinical trial design and therapeutic strategies for ALK-positive NSCLC patients including patients with double genetic aberration of ALK and EGFR.     

Pyrazolone-based anaplastic lymphoma kinase (ALK) inhibitors: control of selectivity by a benzyloxy group

Anaplastic lymphoma kinase (ALK) is transmembrane receptor tyrosine kinase, with oncogenic variants that have been implicated in ALCL, NSCLC and other cancers. Screening of a VEGFR2-biased kinase library resulted in identification of 1 which showed cross-reactivity with ALK. SAR on the indole segment of 1 showed that a subtle structural modification (the ethoxy group of 1 changed to a benzyloxy to generate 5a) enhanced potency (ALK), selectivity for VEGFR2 and IR along with improvement in metabolic stability. From docking studies of ALK versus VEGFR2 kinase, we postulated that the loss of entropy of the VEGFR2 in the bound form with 5a might be the origin of the reduced activity against that protein. Modification of the heterocyclic segment showed that thiazole-bearing pyrazolones preserved enzyme potency, and enhanced inhibition of NPM-ALK autophosphorylation in ALK-positive ALCL cells (Karpas-299). SAR of the benzyloxy group resulted in compounds which demonstrated good cellular potency in Karpas-299 cells. Compound 8 showed best overall profile for the series with broad kinome selectivity and liver micorsome stability. Compound 8 showed reasonable iv PK in rat, but with little oral exposure.     

NK92-CD16 cells are cytotoxic to non-small cell lung cancer cell lines that have acquired resistance to tyrosine kinase inhibitors

BackgroundTreatment with tyrosine kinase inhibitors (TKIs) has improved the outcomes for patients with non-small cell lung cancer (NSCLC) harboring targetable driver mutations. However, acquired resistance to TKIs invariably develops within approximately 1 year of treatment by various mechanisms, including gatekeeper mutations, alternative pathway activation and histological transformations. Because immunotherapy is an option for patients with drug-resistant cancers, we generated several TKI-resistant NSCLC cell lines in vitro, and then evaluated the cytotoxicity of NK92-CD16 cells to these resistant cells.Materials and MethodsTKI-resistant NSCLC cells (H3122CR1, H3122LR1, H3122CR1LR1, PC-9GR, PC-9ER, EBC-CR1 and EBC-CR2) were established from NCI-H3122 (EML4-ALK fusion), PC-9 (EGFR exon19 deletion) and EBC-1 (MET amplification) after continuous exposure to crizotinib, ceritinib, gefitinib, erlotinib and capmatinib. Expression of ligands for natural killer (NK) cell receptors and total EGFR were analyzed using flow cytometry. NK cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) using anti-EGFR monoclonal antibody (mAb) cetuximab were measured using NK92-CD16 as effectors and detected using the ⁵¹Chromium-release assay.ResultsWe found that NK92-CD16 cells preferentially killed TKI-resistant NSCLC cells when compared with their parental NSCLC cells. Mechanistically, intracellular adhesion molecule 1 (ICAM-1) was up-regulated in the TKI-resistant NSCLC cells and patients’ tumors, and the ICAM-1 up-regulated cancer cells lines were less susceptible to NK cytotoxicity by blocking ICAM-1. Moreover, NK92-CD16 cell-induced cytotoxicity toward TKI-resistant NSCLC cells was enhanced in the presence of cetuximab, an EGFR-targeting mAb.ConclusionThese data suggest that combinational treatment with NK cell–based immunotherapy and cetuximab may be promising for patients with TKI-resistant NSCLC.     

Molecular Typing of Lung Adenocarcinoma on Cytological Samples Using a Multigene Next Generation Sequencing Panel

Identification of driver mutations in lung adenocarcinoma has led to development of targeted agents that are already approved for clinical use or are in clinical trials. Therefore, the number of biomarkers that will be needed to assess is expected to rapidly increase. This calls for the implementation of methods probing the mutational status of multiple genes for inoperable cases, for which limited cytological or bioptic material is available. Cytology specimens from 38 lung adenocarcinomas were subjected to the simultaneous assessment of 504 mutational hotspots of 22 lung cancer-associated genes using 10 nanograms of DNA and Ion Torrent PGM next-generation sequencing. Thirty-six cases were successfully sequenced (95%). In 24/36 cases (67%) at least one mutated gene was observed, including EGFR, KRAS, PIK3CA, BRAF, TP53, PTEN, MET, SMAD4, FGFR3, STK11, MAP2K1. EGFR and KRAS mutations, respectively found in 6/36 (16%) and 10/36 (28%) cases, were mutually exclusive. Nine samples (25%) showed concurrent alterations in different genes. The next-generation sequencing test used is superior to current standard methodologies, as it interrogates multiple genes and requires limited amounts of DNA. Its applicability to routine cytology samples might allow a significant increase in the fraction of lung cancer patients eligible for personalized therapy.     

Sulforaphane attenuates EGFR signaling in NSCLC cells

Background

EGFR, a receptor tyrosine kinase (RTK), is frequently overexpressed and mutated in non-small cell lung cancer (NSCLC). Tyrosine kinase inhibitors (TKIs) have been widely used in the treatment of many cancers, including NSCLC. However, intrinsic and acquired resistance to TKI remains a common obstacle. One strategy that may help overcome EGFR-TKI resistance is to target EGFR for degradation. As EGFR is a client protein of heat-shock protein 90 (HSP90) and sulforaphane is known to functionally regulate HSP90, we hypothesized that sulforaphane could attenuate EGFR-related signaling and potentially be used to treat NSCLC.

Results

Our study revealed that sulforaphane displayed antitumor activity against NSCLC cells both in vitro and in vivo. The sensitivity of NSCLC cells to sulforaphane appeared to positively correlate with the inhibition of EGFR-related signaling, which was attributed to the increased proteasomal degradation of EGFR. Combined treatment of NSCLC cells with sulforaphane plus another HSP90 inhibitor (17-AAG) enhanced the inhibition of EGFR-related signaling both in vitro and in vivo.

Conclusions

We have shown that sulforaphane is a novel inhibitory modulator of EGFR expression and is effective in inhibiting the tumor growth of EGFR-TKI-resistant NSCLC cells. Our findings suggest that sulforaphane should be further explored for its potential clinical applications against NSCLC.     

Sirt1 protects from K‐Ras‐driven lung carcinogenesis

The NAD⁺‐dependent deacetylase SIRT1 can be oncogenic or tumor suppressive depending on the tissue. Little is known about the role of SIRT1 in non‐small cell lung carcinoma (NSCLC), one of the deadliest cancers, that is frequently associated with mutated K‐RAS. Therefore, we investigated the effect of SIRT1 on K‐RAS‐driven lung carcinogenesis. We report that SIRT1 protein levels are downregulated by oncogenic K‐RAS in a MEK and PI3K‐dependent manner in mouse embryo fibroblasts (MEFs), and in human lung adenocarcinoma cell lines. Furthermore, Sirt1 overexpression in mice delays the appearance of K‐Ras^G12V‐driven lung adenocarcinomas, reducing the number and size of carcinomas at the time of death and extending survival. Consistently, lower levels of SIRT1 are associated with worse prognosis in human NSCLCs. Mechanistically, analysis of mouse Sirt1‐Tg pneumocytes, isolated shortly after K‐Ras^G12V activation, reveals that Sirt1 overexpression alters pathways involved in tumor development: proliferation, apoptosis, or extracellular matrix organization. Our work demonstrates a tumor suppressive role of SIRT1 in the development of K‐RAS‐driven lung adenocarcinomas in mice and humans, suggesting that the SIRT1–K‐RAS axis could be a therapeutic target for NSCLCs.     

Primary Pulmonary Mucoepidermoid Carcinoma: Histopathological and Moleculargenetic Studies of 26 Cases

Introduction

Pulmonary mucoepidermoid carcinoma (PMEC) is an uncommon neoplasm of the lung and the main salivary gland-type lung carcinoma. The aims of this study were to review the clinicopathological and immunohistochemical features of PMEC and characterize the genetic events in PMEC.

Methods

We reviewed the pathology cases in our hospital and found 34 initially diagnosed PMEC cases, 26 of which were confirmed as PMEC after excluding 8 cases of MEC-like pulmonary carcinoma. The clinicopathological characteristics of the 26 PMEC cases and the 8 cases of MEC-like pulmonary carcinoma were retrospectively reviewed. MAML2 rearrangement was detected by fluorescence In Situ Hybridization (FISH). Immunostains of ALK, calponin, collagen IV, CK7, EGFR, HER2, Ki-67, Muc5Ac, p63, p40, and TTF-1 were performed. DNA was extracted from 23 cases of PMEC. Mutation profiling of the EGFR, KRAS, BRAF, ALK, PIK3CA, PDGFRA, and DDR2 genes were carried out using next-generation sequencing (NGS), Sanger sequencing, and quantitative polymerase chain reaction (QPCR) in 9 successfully amplified cases.

Results

Twenty-six cases of PMEC (18 low-grade, 8 high-grade) included 13 men and 13 women aged 12–79 years. Twenty-two cases had a central/endobronchial growth pattern, and 4 cases had a peribronchial growth pattern. Immunohistochemically, CK7, Muc5Ac, p40, and p63 were positive in all cases (26/26);EGFR was positive in 11 cases (11/26); TTF-1, Calponin, HER2 and ALK were negative in all cases (0/26). MAML2 rearrangement was identified in 12 of 18 PMEC cases. No mutations were detected in any of the 7 genes in the 9 cases that qualified for mutation analysis. Twenty-three PMEC patients had follow-up information with a median interval of 32.6 months. Both the 5- and 10-year overall survival rates (OS) were 72.1%, and a high-grade tumor was an adverse prognostic factor in PMEC. There were 8 cases of MEC-like pulmonary carcinoma aged 36–78 years: 2 cases were located in the bronchus, and 6 cases were located in the lung. p63 and TTF-1 were positive in all cases (8/8), p40 was positive in 5 cases (5/8), and ALK was positive in 5 cases (5/8). No cases of MAML2 rearrangement were detected, but there were 5 cases of ALK rearrangement.

Conclusions

PMEC is a primary malignant pulmonary tumor with a relatively good prognosis that is historically characterized by the presence of mucous cells and a lack of keratinization. There are distinct differences between PMEC and MEC-like pulmonary carcinoma in tumor location preference, immunophenotype, and molecular genetics, and the differential diagnosis is critical due to the therapeutic and prognostic considerations.