Mutation profile and programmed death ligand 1 status of patients with non-small cell lung cancer diagnosed with "adenocarcinoma" and "non-small cell carcinoma favor adenocarcinoma"

BACKGROUND

The terminology for lung cancer diagnosis in small biopsies was adopted in the 2015 World Health Organization classification. If non-small cell lung cancer (NSCLC) has no clear adenocarcinoma (AD) or squamous cell carcinoma morphology, the tumor is further classified based on mucin or immunohistochemical staining as NSCLC favor AD (NFAD), NSCLC favor squamous cell carcinoma, or NSCLC not otherwise specified. Since this new term was defined, the difference between AD and NFAD has not yet been fully explored. This study aimed to examine the differences in clinical background, gene alteration frequency, and programmed death ligand 1 (PD-L1) expression.

METHODS

We included patients diagnosed with AD or NFAD with small samples, and who underwent testing with the Oncomine Dx target test between August 2019 and April 2023 in Kanagawa Cancer Center.

RESULTS

This study comprised 268 patients. A total of 96 patients underwent surgery after AD or NFAD diagnosis. The clinical stage was more advanced and pathological N0 was lower in NFAD than in AD. The pathology of the surgical specimens revealed that solid predominant AD was significantly more common in NFAD than in AD (p < 0.001). In both AD and NFAD, EGFR mutation was the most frequent gene alteration, followed by KRAS mutation. The frequency of EGFR mutations was significantly higher in AD than in NFAD. PD-L1 expression was significantly higher in NFAD than in AD (p < 0.001).

CONCLUSION

This study shows a clear difference between AD and NFAD in terms of cancer progression, pathological features of the main tumor, genetic characteristics, and PD-L1 expression.

Morphological, immune and genetic features in biopsy sample associated with the efficacy of pembrolizumab in patients with non-squamous non-small cell lung cancer

INTRODUCTION

The usefulness of the histopathology of biopsy samples for predicting the efficacy of immunotherapy in non-squamous, non-small cell lung cancer (NSq NSCLC) patients remains unclear.

METHODS

We retrospectively investigated the associations between the histopathological features in biopsy samples and survival outcomes in advanced NSq NSCLC patients receiving pembrolizumab. NSq NSCLC was classified histopathologically as morphological adenocarcinoma or non-small cell carcinoma (NSCC: absence of definitive features of either adenocarcinoma or a squamous morphology). We investigated the association between the tumor morphological features and immune/genetic features by examining the tumor PD-L1 expression and tumor mutation burden (TMB).

RESULTS

Among 33 advanced NSq NSCLC patients with tumor PD-L1 scores ≥ 50% receiving pembrolizumab as first-line therapy, a biopsy diagnosis of NSCC was associated with a significantly longer progression-free survival [median 16.8 vs. 2.3 months; hazard ratio (HR) 0.26; 95% CI 0.10-0.62, P = 0.01] and overall survival (median NR vs. 10.1 months; HR 0.35; 0.12-0.97, P = 0.04) as compared to that of morphological adenocarcinoma. In an analysis of 367 biopsy samples, the NSCC group showed a higher percentage of samples with PD-L1 scores ≥ 50% than the morphological adenocarcinoma group (35% vs. 10%). The NSCC group (n = 8) also showed a significantly higher TMB than the morphological adenocarcinoma group (n = 7) (median 236 vs. 25 mutations/whole exome, P = 0.01).

CONCLUSION

Absence of definitive morphological features in a biopsy sample could be a useful predictor of the efficacy of pembrolizumab in NSq NSCLC patients with tumor PD-L1 scores ≥ 50%, as these tumors are likely to show high tumor PD-L1 expression and high TMB.

Validity of using immunohistochemistry to predict treatment outcome in patients with non-small cell lung cancer not otherwise specified

PURPOSE

Histology samples are important for the appropriate administration of tumor type-specific cytotoxic and molecular-targeted therapies for the treatment of non-small cell lung cancer (NSCLC). When biopsy samples lack a definite morphology, a diagnosis can be selected from three subtypes based on immunohistochemistry (IHC) results, as follows: favor adenocarcinoma (ADC), favor squamous cell carcinoma (SQC), or not otherwise specified (NOS)-null. In terms of patient outcome, however, the validity of IHC-based classifications remains unknown.

METHODS

A large series of 152 patients with advanced NSCLC whose diagnoses had been made based on morphological findings and who had been homogeneously treated were enrolled. We used IHC staining (TTF-1, SP-A, p40, and CK5/6) to examine tumor samples and refined the diagnoses. We then analyzed the pathological subgroups according to the IHC staining results.

RESULTS

IHC profiling resulted in 50% of the cases being classified as favor ADC, 31% being classified as favor SQC, and 19% being classified as NOS-null groups. Compared with the favor ADC and favor SQC groups, the NOS-null group had a significantly poorer outcome. Pemetrexed-containing platinum regimens produced a response rate similar to that of other platinum doublet regimens in the favor ADC group (44% vs. 46%), whereas it produced a poorer response in the favor SQC group (0% vs. 52%) and the NOS-null group (0% vs. 24%). The favor ADC group tended to have a higher percentage of EGFR positivity and ALK positivity than the favor SQC group (25% vs. 11% and 7% vs. 0%, respectively).

CONCLUSIONS

These findings support the use of immunohistological subtyping of NSCLC biopsy specimens to select patient-appropriate treatments.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.

[Large cell carcinoma, lymphoepithelioma-like carcinoma, NUT carcinoma]

The diagnosis of large cell carcinoma can only be made on a sampled resected tumor and should not be applied to biopsies or cytology. In the 2015 WHO classification, the definition of large cell carcinoma is restricted to carcinomas both lacking morphological signs of glandular, squamous or neuroendocrine differentiation and exhibiting a null or unclear phenotype (TTF1-/p40 ou p63 ou CK5/6+ focally). These carcinomas have an adenocarcinoma molecular profile because they harbor a significant number of KRAS and BRAF mutations, a profile that is more similar to adenocarcinoma than squamous cell carcinoma. They also have a worse prognosis than the other types of non-small cell lung carcinoma. Many large cell carcinomas previously classified on morphological data alone are now reclassified in the adenocarcinoma and squamous cell carcinoma types, including immunohistochemical features. The other large cell carcinoma subtypes from the 2004 WHO classification, i.e. large cell neuroendocrine carcinoma and basaloid carcinoma, are grouped respectively with the other neuroendocrine tumors and squamous cell carcinomas. Clear cell and rhabdoid features are now considered as cytological variants that can occur in any histopathological subtype and not as distinct subtypes. Lymphoepithelioma-like carcinoma is moved to the group of other and unclassified carcinomas as NUT carcinoma.

Impact of non-small-cell lung cancer-not otherwise specified immunophenotyping on treatment outcome

INTRODUCTION

The vast majority of non-small-cell lung cancers (NSCLCs) presents as advanced disease, and histological diagnosis is widely based on small samples. The differential activity and toxicity profile of new cytotoxic and molecular-targeted therapies according to histotypes requires a precise subtyping of NSCLC. Immunohistochemistry (IHC) contributes to define the most probable histotype; however, the real impact of IHC characterization of NSCLC-not otherwise specified (NOS) in terms of outcome is not well established.

METHODS

A large series of 224 advanced "nonsquamous" NSCLC diagnosed on small biopsy or cytological samples and homogeneously treated was retrospectively selected, all having adequate follow-up data available. Reviewed diagnoses resulted into two groups: adenocarcinoma (ADC) and NSCLC-NOS. The latter was further characterized by IHC (TTF-1, Napsin-A, p40, and Desmocollin-3) -identify a possible, most probable differentiation lineage.

RESULTS

Sixty-seven percentage of cases were classified as ADC based on morphological examination only ("morphological ADC") and 33% as NSCLC-NOS. IHC profiling of NSCLC-NOS identified 43.2% of cases with an ADC immunophenotype ("NSCLC favor ADC"), 10.8% with a phenotype favoring squamous lineage, and 46% lacking differentiation features. Survival curves confirmed no difference in terms of outcome between the morphological ADC and the NSCLC favor ADC groups, while a significantly poorer outcome was found in the "null" group in terms of best response, progression-free survival or overall survival (OS).

CONCLUSION

Tumors with an IHC profile ADC-like had an OS comparable with that of morphological ADCs. These findings support the use of IHC to optimize lung cancer histological typing and therapy.

Large cell carcinoma of the lung: a tumor in search of an author. A clinically oriented critical reappraisal

Large cell carcinoma (LCC) is a merely descriptive term indicating a subtype of lung cancer with no specific features of small-cell lung cancer (SCLC), adenocarcinoma (ADC) or squamous cell carcinoma (SQC). This diagnosis is allowed on surgical specimens only, whereas its counterpart in biopsy/cytology samples is non-small-cell lung carcinoma (NSCLC), not otherwise specified (NOS). Although these two terms do not fulfill the same concept, they can be interchangeable synonyms at the clinical level, reflecting, in different ways, the inability to define a specific subtype. Immunohistochemistry (IHC), next generation sequencing (NGS) analysis and, historically, electron microscopy have been unveiling diverse cell differentiation lineages in LCC, resulting in LCC-favor ADC, LCC-favor SQC and LCC-favor large-cell neuroendocrine carcinoma (LCNEC), the latter hopefully to be included into the neuroendocrine tumor (NET) group in the future. Paradoxically, however, the interpretation issues of LCC/NSCLC-NOS are not diminishing, but even increasing albeight an accurate diagnosis is oncologically required and crucial. Also, rare LCC/NSCLC-NOS cases exhibiting null/unclear phenotype, are difficult to classify, and this terminology could be maintained for the sake of classification (basically these tumors are serendipitous ADC, as also confirmed by the lack of p40). In this review article, seven relevant issues to LCC have been addressed by using a question-answer methodology, with final key points discussing major interpretation issues. In conclusion, most LCC/NSCLC-NOS may be eventually re-classified and addressed by exploiting IHC and/or molecular testing to satisfy the criteria of precision medicine (the right drug, to the right patient, at the right time).