Correlation of Histologic Subtypes and Molecular Alterations in Pulmonary Adenocarcinoma: Therapeutic and Prognostic Implications

Atypical Histopathological Aspects of Common Types of Lung Cancer-Our Experience and Literature Review

Lung cancer is among the most common oncological diseases regarding incidence and mortality, with most of these having epithelial origins. Pathological reporting of these tumors is conducted according to the 5th edition of the World Health Organisation (WHO) classification of thoracic tumours. This study aims to draw the pathologist's attention to four rare, atypical microscopic aspects that some of the most common types of lung malignancies reveal upon standard evaluation (hematoxylin-eosin stain) that make histopathological diagnosis challenging: acantholytic, pseudoangiosarcomatous, signet ring cell, and clear cell features. Each of these aspects was exemplified by a case diagnosed in the pathology department of the "Marius Nasta" Institute. Furthermore, we analyzed the classification dynamics of different WHO editions and used PubMed to review articles written in English and published in the last eleven years on this subject. Pathologists should be familiar with these unusual aspects to avoid misdiagnoses and to ensure the correct classification of tumors, which is extremely important because these tumor phenotypes have been associated with specific molecular alterations and a worse clinical evolution. There is a need to clarify the histogenesis and associated genetic mutations, given the fact that the rarity of these tumor phenotypes makes their study difficult. Some authors consider these to be overlapping entities; however, we do not encourage this, as they may exhibit different prognoses and various molecular alterations with important therapeutic implications. The signet ring cell feature was associated with ALK rearrangement in lung adenocarcinoma; thus, these patients can benefit from tailored therapy with ALK-tyrosine kinase inhibitors (ALK-TKI). Recent studies associated clear cell morphology with FGFR3-TACC3 fusion, suggesting that patients with this diagnosis may be potentially eligible for FGFR inhibitors. We described, for the first time, the pseudoangiosarcomatous pattern in a case of lung adenocarcinoma; to our knowledge this aspect has only been described until now in the context of squamous cell carcinomas.

The value of prognostic and predictive parameters in early-stage lung adenocarcinomas: A comparison between biopsies and resections

INTRODUCTION

Since lung adenocarcinoma (LUAD) biopsies are usually small, it is questionable if their prognostic and predictive information is comparable to what is offered by large resection specimens. This study compares LUAD biopsies and resection specimens for their ability to provide prognostic and predictive parameters.

METHODS

We selected 187 biopsy specimens with stage I and II LUAD. In 123 cases, subsequent resection specimens were also available. All specimens were evaluated for growth pattern, nuclear grade, fibrosis, inflammation, and genomic alterations. Findings were compared using non-parametric testing for categorical variables. Model performance was assessed using the area under the curve for both biopsies and resection specimens, and overall (OS) and disease-free survival (DFS) was calculated.

RESULTS

The overall growth pattern concordance between biopsies and resections was 73.9%. The dominant growth pattern correlated with OS and DFS in resected adenocarcinomas and for high-grade growth pattern in biopsies. Multivariate analysis of biopsy specimens revealed that T2-tumors, N1-status, KRAS mutations and a lack of other driver mutations were associated with poorer survival. Model performance using clinical, histological and genetic data from biopsy specimens for predicting OS and DSF demonstrated an AUC of 0.72 and 0.69, respectively.

CONCLUSIONS

Our data demonstrated the prognostic relevance of a high-grade growth pattern in biopsy specimens of LUAD. Combining clinical, histological and genetic information in one model demonstrated a suboptimal performance for DFS prediction and good performance for OS prediction. However, for daily practice, more robust (bio)markers are required to predict prognosis and stratify patients for therapy and follow-up.

Proposal of a revised International Association for the Study of Lung Cancer grading system in pulmonary non-mucinous adenocarcinoma: The importance of the lepidic proportion

OBJECTIVES

We aimed to measure the validity of the International Association for the Study of Lung Cancer (IASLC) grading system in Korean patients and propose a modification for an increase of its predictability, especially in grade 2 patients.

MATERIALS AND METHODS

From 2012 to 2017, histopathologic characteristics of 1358 patients with invasive pulmonary adenocarcinoma (stage I-III) from two institutions were retrospectively reviewed and re-classified according to the IASLC grading system. Considering the amount of the lepidic proportion, the validity of the revised model (Lepidic-10), derived from the training cohort (hospital A), was measured using the validation cohort (hospital B). Its predictability was compared to that of the IASLC system.

RESULTS

Of the 1358 patients, 259 had a recurrence, and 189 died during follow-up. The Harrell's concordance index and area under the curve of the IASLC system were 0.685 and 0.699 for recurrence-free survival (RFS) and 0.669 and 0.679 for death, respectively. From the training cohort, the IASLC grade 2 patients were divided into grades 2a and 2b (Lepidic-10 model) with a 10 % lepidic pattern. This new model further distinguished patients in both institutions that had better performance than the IASLC grading (Hospital A, p < 0.001 for RFS and death; Hospital B, p = 0.0215 for RFS, p = 0.0429 for death).

CONCLUSION

The IASLC grading system was easily applicable; its clinical use in predicting the prognosis of Korean patients with pulmonary adenocarcinoma was validated. Furthermore, the introduction of the lepidic proportion as an additional criterion to differentiate grade 2 patients improved its predictability.

Mucoepidermoid carcinoma (MEC) and adenosquamous carcinoma (ASC), the same or different entities?

Mucoepidermoid carcinoma (MEC) and adenosquamous carcinoma (ASC) have overlapping histopathological appearances and sites of occurrence, which may cause diagnostic difficulty impacting subsequent treatment. We conducted a systematic review of the scientific literature to determine whether molecular alterations were sufficiently different in MEC and ASC to aid in classifying the two entities. We searched Medline, Embase and Web of Science for studies reporting molecular determinations of ASC and/or MEC and screened retrieved records for eligibility. Two independent researchers reviewed included studies, assessed methodological quality and extracted data. Of 8623 identified records, 128 articles were included for analysis: 5 which compared the two tumors in the same investigation using the same methods and 123 which examined the tumors separately. All articles, except one were case series of moderate to poor methodological quality. The 5 publications examining both tumors showed that 52/88 (59%) MEC and 0% of 110 ASC had rearrangement of the MAML2 gene as detected by FISH and/or RT-PCR, but did not investigate other genes. In the entire series MEC had MAML2 gene rearrangement in 1337/2009 (66.6%) of tumors studied. The articles examining tumors separately found that MEC had mutations in EGFR (11/329 cases, 3.3%), KRAS (11/266, 4.1%) and ERBB2 (9/126, 7.1%) compared with ASC that had mutations in EGFR (660/1705, 38.7%), KRAS (143/625, 22.9%) and ERBB2 (6/196, 3.1%). The highest level of recurrent mutations was in pancreatic ASC where (108/126, 85.7%) reported mutations in KRAS. The EGFR mutations in ASC were similar in number and kind to those in lung adenocarcinoma. By standards of systematic review methodology and despite the large number of retrieved studies, we did not find adequate evidence for a distinctive molecular profile of either MEC or ASC that could definitively aid in its classification, especially in histologically difficult cases that are negative for MAML2 rearrangement. The case series included in this review indicate the relevance of MAML2 rearrangement to support the diagnosis of MEC, findings that should be confirmed by additional research with adequate study design.

Characteristics and Prognostic Nomogram for Primary Lung Lepidic Adenocarcinoma

Background. Lepidic adenocarcinoma (LPA) is an infrequent subtype of invasive pulmonary adenocarcinoma (ADC). However, the clinicopathological features and prognostic factors of LPA have not been elucidated. Methods. Data from the Surveillance, Epidemiology, and End Results (SEER) database of 4191 LPA patients were retrospectively analyzed and compared with non-LPA pulmonary ADC to explore the clinicopathological and prognosis features of LPA. Univariate and multivariate Cox proportional hazard models were performed to identify independent survival predictors for further nomogram development. The nomograms were validated using the concordance index, receiver operating characteristic curves, and calibration plots, as well as decision curve analysis, in both the training and validation cohorts. Results. Compared with non-LPA pulmonary ADC patients, those with LPA exhibited unique clinicopathological features, including more elderly and female patients, smaller tumor size, less pleural invasion, and lower histological grade and stage. Multivariate analyses showed that age, sex, race, tumor location, primary tumor size, pleural invasion, histological grade, stage, primary tumor surgery, and chemotherapy were independently associated with overall survival (OS) and cancer-specific survival (CSS) in patients with LPA. The nomograms showed good accuracy compared with the actual observed results and demonstrated improved prognostic capacity compared with the TNM stage. Conclusions. LPA is more frequently diagnosed in older people and women. LPA was inclined to be smaller in tumor size and lower in tumor grade and staging, which may indicate a favorable prognosis. The constructed nomograms accurately predict the long-term survival of LPA patients.

Quantitative CT imaging analysis to predict pathology features in patients with a congenital pulmonary airway malformation

BACKGROUND

Risk for infection and potential malignant degeneration are the most common arguments for resecting asymptomatic Congenital Pulmonary Airway Malformations (CPAM). We aimed to investigate if CT- imaging characteristics can be used to predict histopathological features, by using an objective quantitative CT scoring method.

METHODS

Archival CPAM tissue samples were histologically re-assessed and patients who had a pre-operative volumetric CT-scan were included. Lung disease was quantified using the newly-developed congenital lung abnormality quantification(CLAQ) scoring method and obtained percentages were used to predict histopathological signs of inflammation and presence of mucinous proliferation (MP). Because MP is presumed a precursor for mucinous adenocarcinoma in situ (AIS) this method was also used to compare CT-scans of patients with AIS to those with only CPAM.

RESULTS

Thirty-three CPAM patients were included of which 13(39%) had histological signs of inflammation and 8(24%) had a MP. Patients with inflammation had a significantly smaller lesion (14% vs 38%) while those with MP had more extensive disease (54%vs17%). Patients with AIS had a significantly smaller lesion compared to CPAM patients (5%vs29%). Significant predictors for inflammation were smaller lesion size and percentage hypodensity within lesions while a larger lesion size and percentage parenchymal hyperdensity (solid lung tissue components) were predictors for MP as well as AIS.

CONCLUSIONS

Smaller CPAM lesions may be more susceptible to inflammation while larger lesions may be associated with the presence of MP. Parenchymal hyperdensity is found as a predictor for MP as well as AIS and should therefore elicit more extensive gross sampling.

LEVEL OF EVIDENCE

Level III.

FARP1, ARHGEF39, and TIAM2 are essential receptor tyrosine kinase effectors for Rac1-dependent cell motility in human lung adenocarcinoma

Despite the undisputable role of the small GTPase Rac1 in the regulation of actin cytoskeleton reorganization, the Rac guanine-nucleotide exchange factors (Rac-GEFs) involved in Rac1-mediated motility and invasion in human lung adenocarcinoma cells remain largely unknown. Here, we identify FARP1, ARHGEF39, and TIAM2 as essential Rac-GEFs responsible for Rac1-mediated lung cancer cell migration upon EGFR and c-Met activation. Noteworthily, these Rac-GEFs operate in a non-redundant manner by controlling distinctive aspects of ruffle dynamics formation. Mechanistic analysis reveals a leading role of the AXL-Gab1-PI3K axis in conferring pro-motility traits downstream of EGFR. Along with the positive association between the overexpression of Rac-GEFs and poor lung adenocarcinoma patient survival, we show that FARP1 and ARHGEF39 are upregulated in EpCam⁺ cells sorted from primary human lung adenocarcinomas. Overall, our study reveals fundamental insights into the complex intricacies underlying Rac-GEF-mediated cancer cell motility signaling, hence underscoring promising targets for metastatic lung cancer therapy.

Comprehensive analysis of spread through air spaces in lung adenocarcinoma and squamous cell carcinoma using the 8th edition AJCC/UICC staging system

BACKGROUND

This study aimed to comprehensively investigate the effect of spread through air spaces (STAS) on clinicopathologic features, molecular characteristics, immunohistochemical expression, and prognosis in lung adenocarcinomas (ADC) and squamous cell carcinomas (SQCC) based on the 8th edition AJCC/UICC staging system.

METHODS

In total, 303 ADC and 121 SQCC cases were assessed retrospectively. Immunohistochemical staining was performed for E-cadherin, vimentin, Ki67, survivin, Bcl-2, and Bim. Correlations between STAS and other parameters were analyzed statistically.

RESULTS

STAS was observed in 183 (60.4%) ADC and 39 (32.2%) SQCC cases. In ADC, the presence of STAS was associated with wild-type EGFR, ALK and ROS1 rearrangements, low E-cadherin expression, and high vimentin and Ki67 expression. In SQCC, STAS was associated with low E-cadherin expression and high vimentin and survivin expression. Based on univariate analysis, STAS was associated with significantly shorter disease-free survival (DFS) and overall survival (OS) in ADC. In SQCC, STAS tended to be associated with shorter OS. By multivariate analysis, STAS was an independent poor prognostic factor in ADC for DFS but not OS. Stratified analysis showed that STAS was correlated with shorter DFS for stage I, II, IA, IB, and IIA ADC based on univariate analysis and was an independent risk factor for DFS in stage I ADC cases based on multivariate analysis.

CONCLUSIONS

Our findings revealed that STAS is an independent negative prognostic factor for stage I ADC using the new 8th edition AJCC/UICC staging system. Stage I patients with STAS should be followed up more closely and might need different treatment strategies.

Cribriform growth pattern in lung adenocarcinoma: More aggressive and poorer prognosis than acinar growth pattern

The predictive value of prognosis based on the histopathological subtype is a critical criterion in the new classification of lung adenocarcinoma published in 2011 by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) (IASLC/ATS/ERS). In this new classification, the differences of histopathology and prognosis are two considerable parameters to classify the subtypes of lung adenocarcinoma. Cribriform growth pattern is regarded as a variant of acinar growth pattern in lung adenocarcinoma, however, more and more studies pointed out that cribriform growth pattern is associated with more aggressive histopathological structures, higher proportion of recurrence rates, and shorter postoperative survival than acinar growth pattern. These features are similar to solid or micropapillary predominant adenocarcinoma. In this review, we summarized the clinicopathological features, prognosis, and genetic variations of cribriform growth pattern of lung adenocarcinoma, and provided a novel insight into the diagnosis and treatment of cribriform lung adenocarcinoma.

Early KRAS oncogenic driver mutations in nonmucinous tissue of congenital pulmonary airway malformations as an indicator of potential malignant behavior

The potential for malignant degeneration is the most common reason for some practitioners to resect asymptomatic congenital pulmonary airway malformations (CPAMs). We aimed to investigate the potential of various immunohistochemical (IHC) and genomic biomarkers to predict the presence of mucinous proliferations (MPs) in CPAM. Archival CPAM tissue samples were re-assessed and underwent IHC analysis using a panel of differentiating markers (TTF1/CDX2/CC10/MUC2/MUC5AC/p16/p53/DICER1). In each sample, intensity of IHC staining was assessed separately in normal lung tissue, CPAM, and MP tissue, using a semiquantitative approach. Likewise, next-generation targeted sequencing of known adult lung driver mutations, including KRAS/BRAF/EGFR/ERBB2, was performed in all samples with MP and in control samples of CPAM tissue without MP. We analyzed samples of 25 CPAM type 1 and 25 CPAM type 2 and found MPs in 11 samples. They were all characterized by strong MUC5AC expression, and all carried a KRAS mutation in the MP and adjacent nonmucinous CPAM tissue, whereas the surrounding normal lung tissue was negative. By contrast, in less than half (5 out of 12) control samples lacking MP, the CPAM tissue also carried a KRAS mutation. KRAS mutations in nonmucinous CPAM tissue may identify lesions with a potential for malignant degeneration and may guide histopathological assessment and patient follow-up.

Association of histologic subtypes with genetic alteration and PD-L1 expression in pulmonary adenocarcinoma

Genetic alteration and programmed death-ligand 1 (PD-L1) expression have been revealed to be associated with various subtypes of pulmonary adenocarcinoma (ADC). The present study aimed to explore the association between histological subtypes and genetic alterations and PD-L1 expression. A total of 375 cases of pulmonary ADC were included. Genetic alterations were determined using next generation sequencing (NGS) in 136 cases. PD-L1 expression was detected by immunohistochemistry (based on clone 22C3) in the remaining 239 cases. Mutations in the epidermal growth factor receptor gene (EGFR) were detected in 76 (55.8%) cases associated with the papillary subtype (P=0.038). Mutations in the Kirsten rat sarcoma viral oncogene homolog gene (KRAS) were present in 46 (33.8%) cases associated with the lepidic subtype (P<0.001) and mucinous ADC (P=0.037). PD-L1 expression was identified in 63 (26.4%) cases associated with the solid subtype (P<0.001). In conclusion, the present study demonstrated that EGFR and KRAS mutations, alongside PD-L1 protein expression are significantly associated with specific subtypes of pulmonary ADC. These results should aid our ability to accurately select appropriate areas of the heterogeneous tumor for molecular testing methods and to predict patient outcomes and prognosis.

Cytological, histological, and molecular characteristics of pure invasive micropapillary carcinoma of pancreas: A case report

INTRODUCTION

Pure invasive micropapillary carcinoma (IMPC) is a rare histologic subtype of pancreatic cancer which has a high propensity for lymph node metastasis and poor prognosis.

PATIENT CONCERNS

An 81-year-old woman was admitted to our institution with a 3-month history of back pain. Computed tomography of the abdomen and pelvis confirmed the presence of a low-density mass in the tail of the pancreas.

DIAGNOSIS

Endoscopic ultrasound-guided fine needle aspiration cytology (FNAC) from the pancreatic mass showed small tumor cell clusters with three-dimensional aggregates and morula-like structures. The tumor was diagnosed as adenocarcinoma with micropapillary features.

INTERVENTIONS

The patient underwent radical antegrade modular pancreatosplenectomy and regional lymph node dissection. Histological examination showed small clusters of tumor cells that were closely adhered to one another. The cells were located in empty stromal spaces mimicking lymphovascular channels. All tumor cells showed reverse polarity, resulting in an "inside-out" pattern. An extensive search was performed, and no typical ductal adenocarcinoma component was found. The tumor measured 1.5 × 1.3 cm and invaded into the peripancreatic fat tissue without adjacent organ invasion. One of the 12 regional lymph nodes showed metastasis. Ion Torrent next-generation sequencing identified missense mutations in KRAS, TP53, and SMAD4 using the Oncomine Comprehensive Panel version 1.

OUTCOMES

Twelve months following surgical resection the patient remained healthy with no evidence of recurrence at clinical follow-up.

LESSONS

This report highlights the diagnostic features and molecular characteristics of pure pancreatic IMPC and the challenges with diagnosis by FNAC. A centralized and collaborative accumulation of additional cases of pure IMPC could further elucidate its pathogenesis.

New Frontiers for Molecular Pathology

Lung cancer remains a serious oncological problem worldwide. The delayed diagnosis and a prevalence of advanced stages in up to 70% of cases at recognition are still observed. Thanks to targeted therapies and immunotherapy a significant progress in achieving prolonged survival in some lung cancer patients is reported. A precise histopathological diagnosis, especially the recognition of adenocarcinoma, and a progress in the methods of clinical staging underlie the proper qualification of patients for a tailored therapy. The deep molecular characteristics of lung cancer in liquid biopsy, for example blood, bronchoalveolar lavage fluid (BALF), cell suspension from needle aspirates, are currently available. The molecular characteristic has recently been extended with molecular aberrations of BRAF, KRAS, MET, ERBB2, RET, NTRK next to the well-known EGFR mutations and ALK, ROS-1 relocation. The present paper discusses the usefulness of adequate pathological methods and molecular testing for the identification of a broad spectrum of predictive biomarkers for a molecular-directed lung cancer therapy. Immunotherapy with immune checkpoint inhibitors (ICIs) is approved in the first line therapy of advanced non-small-cell lung cancer. To date only PD-L1 expression on tumor cells has been found to be a marker of response to ICIs. The efficacy of ICIs as well as the susceptibility to immune-related adverse events are highly individual, so immune biomarkers are widely investigated. The candidates for predictive factors for ICIs immunotherapy include cancer cell antigenicity, presence of regulatory/suppressory molecules on cancer cells, cancer stem cells or on exosomes, and, on the other hand, an immune status of the patient. Cancers with high immune infiltration in the tumor milieu, referred to as “hot” tumors, seem to ensure a better response to ICIs than the “cold” ones. BALF analysis may replace cancer tissue examination, which is of limited access in advanced stages, for the recognition of the nature of immune response in the tumor environment. Tumor mutational burden (TMB) was shown to correlate with a good response to ICIs, especially when combined with other anticancer therapies. The present paper demonstrates the results of recent studies on lung cancer characteristics which bring us closer to the definition of useful prognostic/predictive factors.

Somatic mutations in kinetochore gene KNSTRN are associated with basal proliferating actinic keratoses and cutaneous squamous cell carcinoma

BACKGROUND

Mutations in kinetochore gene KNSTRN accelerate the development of cutaneous squamous cell carcinoma (SCC) and may correlate with different histological classifications of actinic keratosis (AKs).

OBJECTIVE

To determine KNSTRN gene mutation frequency in healthy skin (HS), actinically damaged skin (ADS), in AKs with different histomorphological gradings and invasive SCCs.

METHODS

All samples were histologically evaluated. AK lesions were additionally classified according to their upwards (AK I-III) and downwards (PRO I-III) directed growth pattern. Mutation analyses of all samples were performed using the Sanger method.

RESULTS

With one exception, all detected mutations in KNSTRN gene showed an alanine-to-glutamate substitution at codon 40 (p.Ala40Glu). p.Ala40Glu mutation was found in 6.9% (2/29) of HS, in 16.1% (5/31) of ADS, in 18.3% (20/109) of AKs and in 30.0% (9/30) of invasive SCCs. Further stratification of AKs using the common AK classification of Röwert-Huber revealed the p.Ala40Glu mutation in 14.7% (5/43), 13.3% (4/30) and 24.4% (11/45) (AK I, II and III). In contrast, the new PRO classification showed a distribution of 3.6% (1/28) in PRO I, 21.7% (13/60) in PRO II and 28.6% (6/21) in PRO III. Mutation frequency in HS showed significant differences compared to AKs classified as PRO III and invasive SCCs (P < 0.05). In contrast, there were no statistically significant differences between HS and AKs when classified according to Röwert-Huber.

CONCLUSIONS

Recurrent somatic mutation p.Ala40Glu in KNSTRN gene is associated with basal proliferating AKs in accordance with invasive SCCs. This supports the impact of basal proliferative pattern in terms of progression.

KRAS-specific Amino Acid Substitutions are Associated With Different Responses to Chemotherapy in Advanced Non-small-cell Lung Cancer

BACKGROUND

Emerging data highlight different clinical behaviors according to KRAS amino acid substitutions (AASs) in patients with non-small-cell lung cancer (NSCLC). We aimed to evaluate whether different KRAS AASs were associated with different responses to chemotherapy.

PATIENTS AND METHODS

We retrospectively reviewed data from 1190 patients with KRAS mutations who underwent first-line platinum-based chemotherapy for stage IV NSCLC. The response to different chemotherapy regimens was evaluated using the Response Evaluation Criteria In Solid Tumors criteria (v 1.1). Overall survival and time to progression (TTP) were secondary endpoints.

RESULTS

Taxane was associated with the best response in the entire cohort (odds ratio, 2.52; 95% confidence interval [CI], 1.82-3.48; P < .001), especially in G12V patients (odds ratio, 2.15; 95% CI, 1.05-4.41; P = .036). Taxane was associated with improved TTP in the entire cohort (hazard ratio [HR], 0.31; 95% CI, 0.26-0.38; P < .001), especially in G13D patients (HR, 0.47; 95% CI, 0.22-1.01; P = .054). Pemetrexed was associated with the worst TTP in the entire cohort, particularly in G12V patients, who had the worst response rates (HR, 0.55; 95% CI, 0.30-0.99; P = .049). No impact on overall survival was observed according to different chemotherapy regimens and AASs.

CONCLUSION

KRAS-specific AAS appears to induce different responses to chemotherapy regimens after first-line platinum-based chemotherapy in advanced NSCLC.

The immunoglobulin-like domain of neuregulins potentiates ErbB3/HER3 activation and cellular proliferation

The neuregulins (NRGs) represent a large family of membrane‐anchored growth factors, whose deregulation may contribute to the pathogenesis of several tumors. In fact, targeting of NRG‐activated pathways has demonstrated clinical benefit. To improve the efficacy of anti‐NRG therapies, it is essential to gain insights into the regions of NRGs that favor their pro‐oncogenic properties. Here, we have addressed the protumorigenic impact of different NRG domains. To do this, deletion mutants affecting different NRG domains were expressed in 293 and MCF7 cells. Of the five forms studied, only the wild‐type and a mutant lacking the Ig‐like domain (NRG^ΔIg) were properly sorted to the plasma membrane. Both forms were released as soluble forms to the culture media. However, the mutant NRG^ΔIg failed to efficiently activate HER2 and HER3 receptors, signaling pathways, and cell proliferation when compared to wild‐type NRG. Treatment with trastuzumab, a humanized antibody used in the breast cancer clinic, inhibited the constitutive activation of HER2, HER3, and downstream signaling in MCF7 cells constitutively expressing wild‐type NRG. In contrast, this treatment had a marginal effect on MCF7‐NRG^ΔIg cells. This study demonstrates that the Ig‐like region of NRGs exerts an important role in their capability to activate ErbB/HER receptors and mitogenic responses. Strategies aimed at targeting NRGs should consider that fact to improve neutralization of the pro‐oncogenic properties of NRGs.

Anaplastic lymphoma kinase (ALK)-expressing Lung Adenocarcinoma with Combined Neuroendocrine Component or Neuroendocrine Transformation: Implications for Neuroendocrine Transformation and Response to ALK-tyrosine Kinase Inhibitors

BACKGROUND

Anaplastic lymphoma kinase tyrosine kinase inhibitors (ALK-TKIs) are usually effective in lung adenocarcinoma patients with anaplastic lymphoma kinase (ALK) rearrangement. However, even after a good response to ALK-TKI therapy, most patients acquire resistance to these agents. Histological transformation is one of several suggested mechanisms of acquired resistance to ALK-TKIs. The clinicopathologic features of four patients with ALK-expressing adenocarcinoma and neuroendocrine features were analyzed.

METHODS

We selected combined neuroendocrine differentiation in pulmonary adenocarcinoma cases with positive ALK immunostaining. Neuroendocrine differentiation was confirmed by CD56 immunohistochemical stain. Additional ALK fluorescence in situ hybridization (FISH) study and epidermal growth factor receptor (EGFR) mutation tests were also performed.

RESULTS

All four cases were positive for ALK immunohistochemistry and no EGFR mutations were detected. Interestingly, the results of ALK FISH assays showed rearrangement in only two cases. Three cases showed combined adenocarcinoma and neuroendocrine component without history of ALK-TKI administration; one of them was treated with crizotinib and experienced partial tumor regression. The remaining case had an adenocarcinoma at initial biopsy and she showed a partial response to crizotinib, and neuroendocrine changes were visible on second biopsy. Then she was treated with ceritinib and achieved a partial response.

CONCLUSION

We suggest that ALK-rearranged adenocarcinoma with combined neuroendocrine component is responsive to ALK-TKIs. Moreover, even after neuroendocrine transformation as a result of resistance to ALK-TKIs, the tumor may have partial response to second generation ALK-TKIs.

Correlation Between Programmed Death Receptor-1 Expression in Tumor-Infiltrating Lymphocytes and Programmed Death Ligand-1 Expression in Non-Small Cell Lung Carcinoma

CONTEXT.—

The interaction between programmed death ligand-1 (PD-L1) and programmed death receptor-1 (PD-1) on activated T cells sends an inhibitory signal that dampens the immune response. Tumors can express PD-L1 and evade the immune system. In advanced non-small cell lung carcinoma, expression of PD-1 in tumor-infiltrating lymphocytes (TILs) correlates with PD-L1 expression in tumor cells (TCs). However, this relationship has not been thoroughly explored in early disease.

OBJECTIVE.—

To investigate the correlation of PD-1 and PD-L1 in non-small cell lung carcinoma tumor samples, with emphasis on stage I disease.

DESIGN.—

Whole tissue sections from non-small cell lung carcinoma tumors were retrospectively evaluated by immunohistochemistry for PD-1 and PD-L1 expression. The scoring was based on the percentage of cells positive for PD-1 in TILs and PD-L1 in TCs and tumor-infiltrating immune cells (ICs).

RESULTS.—

Expression of PD-1 in TILs was observed in 147 of 161 non-small cell lung carcinoma cases (91%). The majority of cases negative for PD-1 also lacked PD-L1 in TCs. The 68 cases with highest PD-1 expression in TILs included 33 (49%) with expression of PD-L1 in TCs and ICs. Strong correlations were observed in patients with elevated PD-1 expression in TILs and PD-L1 in TCs ( P = .01) and ICs ( P = .003). Expression of PD-1 also correlated with increased PD-L1 in TCs and ICs when the 2 were grouped together ( P < .001). Finally, stage I patients with negative PD-1 and PD-L1 expression showed trends toward increased disease-specific survival.

CONCLUSIONS.—

Expression of PD-1 in TILs correlates with PD-L1 expression in both TCs and ICs. Furthermore, negative expression of PD-1 and PD-L1 suggest trends toward disease-specific survival, even in early disease stages.