The impact of immunohistochemistry on the classification of lung tumors

Unraveling the influence of TTF-1 expression on immunotherapy outcomes in PD-L1-high non-squamous NSCLC: a retrospective multicenter study

Introduction

Several studies explored the association between thyroid transcription factor-1 (TTF-1) and the therapeutic efficacy of immunotherapy. However, the effect of TTF-1 on the therapeutic efficacy of programmed death-1 (PD-1) inhibitor/chemoimmunotherapy in patients with non-squamous non-small cell lung cancer (non-Sq NSCLC) with a programmed death-ligand 1 (PD-L1) tumor proportion score of 50% or more who are highly susceptible to immunotherapy remains unresolved. Therefore, we evaluated whether TTF-1 has a clinical impact on this population.

Methods

Patients with non-Sq NSCLC and high PD-L1 expression who received PD-1 inhibitor monotherapy or chemoimmunotherapy between May 2017 and December 2020 were retrospectively enrolled. Treatment efficacy was compared after adjusting for baseline differences using propensity score matching.

Results

Among the 446 patients with NSCLC with high PD-L1 expression, 266 patients with non-Sq NSCLC were analyzed. No significant differences in therapeutic efficacy were observed between the TTF-1-positive and -negative groups in the overall and propensity score-matched populations. Of chemoimmunotherapy, pemetrexed containing regimen significantly prolonged progression-free survival compared to chemoimmunotherapy without pemetrexed, regardless of TTF-1 expression (TTF1 positive; HR: 0.46 (95% Confidence interval: 0.26-0.81), p<0.01, TTF-1 negative; HR: 0.29 (95% Confidence interval: 0.09-0.93), p=0.02).

Discussion

TTF-1 expression did not affect the efficacy of PD-1 inhibitor monotherapy or chemoimmunotherapy in patients with non-Sq NSCLC with high PD-L1 expression. In this population, pemetrexed-containing chemoimmunotherapy demonstrated superior anti-tumor efficacy, irrespective of TTF-1 expression.

Lack of imbalance between the master regulators TTF1/NKX2-1 and ΔNp63/p40 implies adverse prognosis in non-small cell lung cancer

The transcription factors TTF1/NKX2-1 and ΔNp63/p40 are the counterposed molecular markers associated with the main Non-Small Cell Lung Cancer subtypes: TTF1 for adenocarcinoma, p40 for squamous cell carcinoma. Although they generally display a mutually exclusive expression, some exceptions exist simultaneously lacking or (very rarely) expressing both markers, either pattern being associated to poor prognosis. Hence, we quantitatively analyzed the relationship between their coordinated activity and prognosis. By analyzing the respective downstream transcriptional programs of the two genes, we defined a simple quantitative index summarizing the amount of mutual exclusivity between their activities, called Mean Absolute Activity (MAA). Systematic analysis of the MAA index in a dataset of 1018 NSCLC samples replicated on a validation dataset of 275 showed that the loss of imbalance between TTF-1 and p40 corresponds to a steady, progressive reduction in both overall and recurrence-free survival. Coherently, samples correspondent to more balanced activities were enriched for pathways related to increased malignancy and invasiveness. Importantly, multivariate analysis showed that the prognostic significance of the proposed index MAA is independent of other clinical variables including stage, sex, age and smoke exposure. These results hold irrespectively of tumor morphology across NSCLC subtypes, providing a unifying description of different expression patterns.

Association of thyroid transcription factor-1 with the efficacy of immune-checkpoint inhibitors in patients with advanced lung adenocarcinoma

Background

We aimed to identify the relationship between thyroid transcription factor‐1 (TTF‐1) expression of lung adenocarcinoma and the efficacy of immune‐checkpoint inhibitor (ICI) therapy.

Methods

This retrospective multicenter study comprised patients with advanced lung adenocarcinoma treated with ICI monotherapy. We collected clinical medical records including data on TTF‐1 expression and analyzed the relationship between TTF‐1 expression and programmed death‐ligand 1 tumor proportion score (PD‐L1 TPS), objective response rate (ORR), progression‐free survival (PFS), and overall survival (OS).

Results

In total, 108 patients with lung adenocarcinoma were analyzed. The rate of TPS ≥1% and ≥50% in patients with positive TTF‐1 expression was significantly higher than that in patients with negative TTF‐1 expression (88% vs. 60%, p < 0.001; 65% vs. 24%, p < 0.001). The ORR was significantly higher in TTF‐1 positive patients than in TTF‐1‐negative patients (38% vs. 8%, p = 0.003). Among patients with TPS ≥50% and 1%–49%, the ORR in TTF‐1 positive and negative patients was 48% (26/54) versus 17% (1/6) (p = 0.21), and 32% (6/19) versus 11% (1/9) (p = 0.37), respectively. The ORR for patients with TPS <1% was 0% in both the TTF‐1 negative and positive cases. The median PFS and OS was significantly longer in TTF‐1‐positive patients than in TTF‐1‐negative patients (5.4 vs. 1.6 months, p < 0.001; 18.2 vs. 8.0 months, p = 0.041). Multivariate analysis revealed that TTF‐1‐negative status was an independent unfavorable prognostic factor for PFS.

Conclusion

Patients with TTF‐1‐positive status receiving ICI monotherapy showed better outcomes than those with TTF‐1‐negative lung adenocarcinoma.

Anti-CK7/CK20 Immunohistochemistry Did Not Associate with the Metastatic Site in TTF-1-Negative Lung Cancer

Anti-CK7 and anti-CK20 immunohistochemistry is sometimes used to establish a diagnosis of primary lung cancer. We performed a retrospective study on the value of anti-CK7 and anti-CK20 immunohistochemistry in 359 biopsies of patients with suspected lung carcinoma in order to assess the usefulness of these antibodies in the evaluation of lung tumors in biopsies. Our results showed TTF-1 positivity in 73.3% of patients. EGFR mutations and ALK rearrangements were significantly different between TTF-1 positive and TTF-1 negative tumors (p < 0.001 and p = 0.023, respectively). Our results show a significant difference (p < 0.001) between TTF-1 positive and TTF-1 negative carcinomas with a median survival of 21.97 months (CI95% = 17.48−30.9 months) and 6.52 months (CI95% = 3.34−10.3 months), respectively. In the group of TTF-1 negative patients, anti-CK7 and CK20 immunohistochemistry was performed in 70 patients and showed CK7+/CK20- staining in 61 patients (87.1%), CK7-/CK20- in 4 patients (5.7%), CK7+/CK20+ in 3 patients (4.3%), and CK7-/CK20- in 2 patients (2.8%). No specific or molecular pattern was found in these groups of CK7/CK20 combinations. In total, this work brings arguments concerning the uselessness of anti-CK7/CK20 immunohistochemistry in the case of suspicion of primary lung cancer in biopsies.

Coexpression of ΔNp63/p40 and TTF1 Within Most of the Same Individual Cells Identifies Life-Threatening NSCLC Featuring Squamous and Glandular Biphenotypic Differentiation: Clinicopathologic Correlations

Introduction

Double occurrence of TTF1 and ΔNp63/p40 (henceforth, p40) within the same individual cells is exceedingly rare in lung cancer. Little is known on their biological and clinical implications.

Methods

Two index cases immunoreactive for both p40 and TTF1 and nine tumors selected from The Cancer Genome Atlas (TCGA) according to the mRNA levels of the two relevant genes entered the study.

Results

The two index cases were peripherally located, poorly differentiated, and behaviorally unfavorable carcinomas, which shared widespread p40 and TTF1 decoration within the same individual tumor cells. They also retained SMARCA2 and SMARCA4 expression, while variably stained for p53, cytokeratin 5, and programmed death-ligand 1. A subset of basal cells p40+/TTF1+ could be found in normal distal airways. Biphenotypic glandular and squamous differentiation was unveiled by electron microscopy, along with EGFR, RAD51B, CCND3, or NF1 mutations and IGF1R, MYC, CCND1, or CDK2 copy number variations on next-generation sequencing analysis. The nine tumors from TCGA (0.88% of 1018 tumors) shared the same poor prognosis, clinical presentation, and challenging histology and had activated pathways of enhanced angiogenesis and epithelial-mesenchymal transition. Mutation and copy number variation profiles did not differ from the other TCGA tumors.

Conclusions

Double p40+/TTF1+ lung carcinomas are aggressive and likely underrecognized non-small cell carcinomas, whose origin could reside in double-positive distal airway stem-like basal cells through either de novo-basal-like or differentiating cell mechanisms according to a model of epithelial renewal.

Histopathologic and molecular profiling of lung adenocarcinoma skin metastases reveals specific features

AIMS

Little is known regarding the histopathological and molecular features of lung adenocarcinoma skin metastases. Our study is the largest to comprehensively explore these to date.

METHODS AND RESULTS

We performed a retrospective cohort study analysing 42 lung adenocarcinoma skin metastasis samples obtained from a database of 2659 lung adenocarcinomas collected between 2010 to 2020. EGFR exon 19 deletion was detected in one patient, and KRAS mutations were detected in 12 (33.3%) patients. The PD-L1 tumour proportion score was <1% in 27 patients, ≥1% and <50% in 8 patients, ≥50% in 6 patients, and not assessable in one patient. We showed that the predominant histopathologic subtype is different from that at other metastatic sites (p=0.024). TTF-1 was more often negative in skin metastases compared to other sites (p<0.001). The EGFR mutation rate tended to be lower for skin metastases compared to other sites (p=0.079). Skin metastases were associated with a high rate of PD-L1-negative cases (p=0.022).

CONCLUSION

Our work shows that the skin metastases of lung adenocarcinoma have a specific histopathologic profile.

Morphologic and molecular classification of lung neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) of the lung encompass neuroendocrine tumors (NETs) composed of typical (TC) and atypical (AC) carcinoids and full-fledged carcinomas (NECs) inclusive of large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCLC). NETs and NECs are thought to represent distinct and separate lesions with neither molecular overlap nor common developmental continuum. Two perspectives were addressed regarding the morphologic and molecular classification of lung NENs: (i) a supervised approach by browsing the traditional classification, the relevant gene alterations, and their clinical implications; and (ii) an unsupervised approach, by reappraising neoplasms according to risk factors and natural history of disease to construct an interpretation model relied on biological data. We herein emphasize lights and shadows of the current classification of lung NENs and provide an alternative outlook on these tumors focused on what we currently know about the biological determinants and the natural history of disease.

Clinical implications of lung neuroendocrine neoplasm classification

INTRODUCTION

Neuroendocrine neoplasms of the lung (Lung NENs) encompass NE tumors (NETs), which are in turn split into typical and atypical carcinoids, and NE carcinomas (NECs), which group together small-cell carcinoma and large-cell NE carcinoma. This classification is the current basis for orienting the daily practice of these patients, with diagnostic, prognostic, and predictive inferences.

AREAS COVERED

The clinical implications of lung NEN classification are addressed according to three converging perspectives, which were dissected through an extensive literature overview: (1) how to put intratumor heterogeneity into the context of the current classification; (2) how to contextualize immunohistochemistry markers to improve diagnosis, prognosis, and therapy prediction; and (3) how to use immuno-oncology strategies for life-threatening NECs, which still account for 90% or more of lung NENs.

EXPERT OPINION

We provide practical insights to account for intratumor heterogeneity, practice the choice of immunohistochemistry markers, and emphasize once again the added value of immuno-oncology in the setting of personalized medicine of lung NENs.

Determining factors of endobronchial ultrasound-guided transbronchial needle aspiration specimens for lung cancer subtyping and molecular testing

Objective:

This study is to explore the determining factors for testing epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) fusion after subtyping by immunohistochemistry (IHC) using samples obtained from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

Materials and Methods:

Patients suspected with advanced lung cancer were performed EBUS-TBNA without rapid on-site evaluation(ROSE) from January 2015 to March 2016 in Shanghai Chest Hospital. All samples diagnosed as lung cancer by histopathology underwent IHC to identify subtypes. EGFR mutation and ALK fusion were tested in adenocarcinoma and non-small-cell lung cancer-not otherwise specified (NSCLC-NOS) using remnant tissue samples.

Results:

A total of 453 patients were diagnosed with lung cancer, including 44.15% (200/453) with adenocarcinoma and 11.04% (50/453) with NSCLC-NOS. With the average passes of 3.41 ± 0.68, samples obtained from EBUS-TBNA were adequate for performing EGFR mutation and ALK fusion gene analysis in 80.4% (201/250) of specimens after routine IHC. On univariate analysis, successful molecular testing was associated with passes per lesion (P = 3.80E-05), long-axis diameters (P = 6.00E-06) and short-axis diameters (P = 4.77E-04), and pathology subtypes of lesions (P = 3.00E-03). Multivariate logistic regression revealed that passes per lesion (P = 1.00E-03), long-axis diameters (P = 3.50E-02), and pathology subtypes (P = 8.00E-03) were independent risk factors associated with successful molecular testing.

Conclusions:

With at least three passes of per lesion, EBUS-TBNA is an efficient method to provide adequate samples for testing of EGFR mutation and ALK gene arrangement following routine histopathology and IHC subtyping. Determining factors associated with successful pathology subtyping and molecular testing using samples obtained by EBUS-TBNA are passes of per lesion, long-axis diameter, and pathology subtypes. During the process of EBUS-TBNA, selecting larger lymph nodes and the puncturing at least 3 passes per lesion may result in higher success rate in lung cancer subtyping and molecular testing.

The diagnosis of non-small cell lung cancer in the molecular era

Lung carcinoma is the leading cause of cancer mortality for both genders in the United States and throughout the world. Many of these tumors are being diagnosed with minimally invasive means resulting in small samples. There is a need to extract an increasing amount of therapeutic and prognostic information from progressively smaller samples. Collaboration among clinicians and pathologists is needed to produce a comprehensive final diagnosis in patients with lung cancer. This collaboration facilitates triage of small samples for ancillary studies including molecular testing. What follows represents a review of the current required testing for lung cancer specimens, an example of an algorithm currently employed at the Cleveland Clinic so that all required tests can be performed even on the smallest of specimens and suggestions on how pathologists may approach this new era of "doing more with less".

Lung cancer biopsy: Can diagnosis be changed after immunohistochemistry when the H&E-Based morphology corresponds to a specific tumor subtype?

OBJECTIVES

Advancements in non-small cell lung cancer treatment based on targeted therapies have made the differentiation between adenocarcinoma and squamous cell carcinoma increasingly important. Pathologists are challenged to make the correct diagnosis in small specimens. We studied the accuracy of an immunohistochemical panel in subclassifying non-small cell lung cancer in routine small biopsies and compared the results with the diagnosis from resected lung specimens, autopsy samples or biopsied/resected metastases.

METHODS

In total, 340 lung cancer biopsies were investigated for the expression of CK5, TTF1, p63 and surfactant.

RESULTS

We characterized 166 adenocarcinomas and 124 squamous cell carcinomas. Overall, 85% of cases displayed binary staining (TTF1 positive/p63 negative, and vice versa). The diagnoses of ten cases with a morphology that indicated a specific tumor subtype were changed after immunohistochemistry (IHC). A second specimen was available for 71 patients, and the first diagnosis at biopsy was confirmed in 95% of these cases. Most non-small cell lung cancer cases present a binary immunohistochemical profile in small biopsies, contributing to good diagnostic accuracy with routine markers. In a small proportion of cases, the diagnosis can be changed after IHC even when the morphological aspects indicate one specific tumor subtype.

CONCLUSIONS

We recommend that routine small biopsies of lung cancer without classic morphology should be subjected to a minimum immunohistochemical panel to differentiate adenocarcinoma from squamous cell carcinoma.

Classification of pulmonary neuroendocrine tumors: new insights

Neuroendocrine tumors of the lung (Lu-NETs) embrace a heterogeneous family of neoplasms classified into four histological variants, namely typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Defining criteria on resection specimens include mitotic count in 2 mm2 and the presence or absence of necrosis, alongside a constellation of cytological and histological traits including cell size and shape, nuclear features and overall architecture. Clinically, TC are low-grade malignant tumors, AC intermediate-grade malignant tumors and SCLC/LCNEC high-grade malignant full-blown carcinomas with no significant differences in survival between them. Homologous tumors arise in the thymus that occasionally have some difficulties in differentiating from the lung counterparts when presented with large unresectable or metastatic lesions. Immunohistochemistry (IHC) helps refine NE diagnosis at various anatomical sites, particularly on small-sized tissue material, in which only TC and small cell carcinoma categories can be recognized easily on hematoxylin & eosin stain, while AC and LCNEC can only be suggested on such material. The Ki-67 labeling index effectively separates carcinoids from small cell carcinoma and may prove useful for the clinical management of a metastatic disease to help the therapeutic decision-making process. Although carcinoids and high-grade neuroendocrine carcinomas in the lung and elsewhere make up separate tumor categories on molecular grounds, emerging data supports the concept of secondary high-grade NETs arising in the preexisting carcinoids, whose clinical and biological relevance will have to be placed into the proper context for the optimal management of these patients. In this review, we will discuss the selected, recent literature with a focus on current issues regarding Lu-NET nosology, i.e., classification, derivation and tumor evolution.

PD-L1 expression in pleomorphic, spindle cell and giant cell carcinoma of the lung is related to TTF-1, p40 expression and might indicate a worse prognosis

Lung sarcomatoid carcinoma of the lung is a rare tumor with a poor prognosis. More than 90% of them are pleomorphic, spindle cell and giant cell carcinoma (PSCGCC). This rare subtype of lung cancer is thought to be more resistant to chemotherapy, and a small subset of them seems to exhibit targetable mutations. Immunotherapy against PD1/PDL-1 is a new emerging treatment, and might be of interest in PSGSCC because they frequently express PD-L1. The aim of our work is to evaluate PD1 and PDL-1 expression in a surgical series of lung PSCGCC and their relationship with morphological and immunohistochemical parameters and prognosis. Thirty-six patients who underwent surgical resection of a PSGSCC were included. PD-L1 (E1L3N) expression on tumor cells and PD1 (NAT105) expression by tumor infiltrating lymphocytes (TILs) were performed by immunohistochemistry. Results were compared to immunohistochemistry tests of TTF1, Napsin A, p40 and to molecular study of EGFR, KRAS, BRAF and HER2. Seventy-five % of PSCGCC were considered as positive for PD-L1.PD-L1 expression in PSGSCC is associated with TTF-1 and/or Napsin A expression (47.2%, p = 0.039). Few p40 positive PSCGCC expressed PD-L1 (8.3%, p = 0.013). PD1 expression was not related to TTF-1 and/or Napsin A expression (p = 0.47), p40 expression (p = 0.68) or survival (p = 0.14). PD-L1 or PD1 expression were not related to the age, gender, pT, pN, stage, visceral pleura invasion, histopathological subtype, the presence of giant cell component, the predominance of sarcomatoid component, and the presence of EGFR or BRAF or HER2 or PIK3CA mutation (p>0.05). PD-L1 expression was correlated with a worse overall survival in PSCGCC (p = 0.045). PD-L1 expression is frequent in PSCGCC and might be associated with the expression of adenocarcinoma markers (TTF-1, Napsin A) or the lack of expression of squamous cell carcinoma marker (p40).