Expression patterns and prognostic relevance of subtype-specific transcription factors in surgically resected small-cell lung cancer: an international multicenter study.

The tissue distribution and prognostic relevance of subtype-specific proteins (ASCL1, NEUROD1, POU2F3, YAP1) present an evolving area of research in small-cell lung cancer (SCLC). The expression of subtype-specific transcription factors and P53 and RB1 proteins were measured by immunohistochemistry (IHC) in 386 surgically resected SCLC samples. Correlations between subtype-specific proteins and in vitro efficacy of various therapeutic agents were investigated by proteomics and cell viability assays in 26 human SCLC cell lines. Besides SCLC-A (ASCL1-dominant), SCLC-AN (combined ASCL1/NEUROD1), SCLC-N (NEUROD1-dominant), and SCLC-P (POU2F3-dominant), IHC and cluster analyses identified a quadruple-negative SCLC subtype (SCLC-QN). No unique YAP1-subtype was found. The highest overall survival rates were associated with non-neuroendocrine subtypes (SCLC-P and SCLC-QN) and the lowest with neuroendocrine subtypes (SCLC-A, SCLC-N, SCLC-AN). In univariate analyses, high ASCL1 expression was associated with poor prognosis and high POU2F3 expression with good prognosis. Notably, high ASCL1 expression influenced survival outcomes independently of other variables in a multivariate model. High POU2F3 and YAP1 protein abundances correlated with sensitivity and resistance to standard-of-care chemotherapeutics, respectively. Specific correlation patterns were also found between the efficacy of targeted agents and subtype-specific protein abundances. In conclusion, we investigated the clinicopathological relevance of SCLC molecular subtypes in a large cohort of surgically resected specimens. Differential IHC expression of ASCL1, NEUROD1, and POU2F3 defines SCLC subtypes. No YAP1-subtype can be distinguished by IHC. High POU2F3 expression is associated with improved survival in a univariate analysis, whereas elevated ASCL1 expression is an independent negative prognosticator. Proteomic and cell viability assays of human SCLC cell lines revealed distinct vulnerability profiles defined by transcription regulators. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Potential Association of Cytochrome P450 Copy Number Alteration in Tumour with Chemotherapy Resistance in Lung Adenocarcinoma Patients.

Resistance to anticancer agents is a major obstacle to efficacious tumour therapy and responsible for high cancer-related mortality rates. Some resistance mechanisms are associated with pharmacokinetic variability in anticancer drug exposure due to genetic polymorphisms of drug-metabolizing cytochrome P450 (CYP) enzymes, whereas variations in tumoural metabolism as a consequence of CYP copy number alterations are assumed to contribute to the selection of resistant cells. A high-throughput quantitative polymerase chain reaction (qPCR)-based method was developed for detection of CYP copy number alterations in tumours, and a scoring system improved the identification of inappropriate reference genes that underwent deletion/multiplication in tumours. The copy numbers of both the target (CYP2C8, CYP3A4) and the reference genes (ALB, B2M, BCKDHA, F5, CD36, MPO, TBP, RPPH1) established in primary lung adenocarcinoma by the qPCR-based method were congruent with those determined by next-generation sequencing (for 10 genes, slope = 0.9498, r2 = 0.72). In treatment naïve adenocarcinoma samples, the copy number multiplication of paclitaxel-metabolizing CYP2C8 and/or CYP3A4 was more prevalent in non-responder patients with progressive disease/exit than in responders with complete remission. The high-throughput qPCR-based method can become an alternative approach to next-generation sequencing in routine clinical practice, and identification of altered CYP copy numbers may provide a promising biomarker for therapy-resistant tumours.

Spatially Resolved Proteomic and Transcriptomic Profiling of Anaplastic Lymphoma Kinase-Rearranged Pulmonary Adenocarcinomas Reveals Key Players in Inter- and Intratumoral Heterogeneity.

Pulmonary adenocarcinomas (pADCs) with an ALK rearrangement are a rare cancer subtype, necessitating comprehensive molecular investigations to unravel their heterogeneity and improve therapeutic strategies. In this pilot study, we employed spatial transcriptomic (NanoString GeoMx) and proteomic profiling to investigate seven treatment-naïve pADCs with an ALK rearrangement. On each FFPE tumor slide, 12 smaller and 2-6 larger histopathologically annotated regions were selected for transcriptomic and proteomic analysis, respectively. The correlation between proteomics and transcriptomics was modest (average Pearson's r = 0.43 at the gene level). Intertumoral heterogeneity was more pronounced than intratumoral heterogeneity, and normal adjacent tissue exhibited distinct molecular characteristics. We identified potential markers and dysregulated pathways associated with tumors, with a varying extent of immune infiltration, as well as with mucin and stroma content. Notably, some markers appeared to be specific to the ALK-driven subset of pADCs. Our data showed that within tumors, elements of the extracellular matrix, including FN1, exhibited substantial variability. Additionally, we mapped the co-localization patterns of tumor microenvironment elements. This study represents the first spatially resolved profiling of ALK-driven pADCs at both the gene and protein expression levels. Our findings may contribute to a better understanding of this cancer type prior to treatment with ALK inhibitors.

Proteomic Workflows for High-Quality Quantitative Proteome and Post-Translational Modification Analysis of Clinically Relevant Samples from Formalin-Fixed Paraffin-Embedded Archives.

Well-characterized archival formalin-fixed paraffin-embedded (FFPE) tissues are of much value for prospective biomarker discovery studies, and protocols that offer high throughput and good reproducibility are essential in proteomics. Therefore, we implemented efficient paraffin removal and protein extraction from FFPE tissues followed by an optimized two-enzyme digestion using suspension trapping (S-Trap). The protocol was then combined with TMTpro 16plex labeling and applied to lung adenocarcinoma patient samples. In total, 9585 proteins were identified, and proteins related to the clinical outcome were detected. Because acetylation is known to play a major role in cancer development, a fast on-trap acetylation protocol was developed for studying endogenous lysine acetylation, which allows identification and localization of the lysine acetylation together with quantitative comparison between samples. We demonstrated that FFPE tissues are equivalent to frozen tissues to study the degree of acetylation between patients. In summary, we present a reproducible sample preparation workflow optimized for FFPE tissues that resolves known proteomic-related challenges. We demonstrate compatibility of the S-Trap with isobaric labeling and for the first time, we prove that it is feasible to study endogenous lysine acetylation stoichiometry in FFPE tissues, contributing to better utility of the existing global tissue archives. The MS proteomic data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the data set identifiers PXD020157, PXD021986, and PXD021964.

Prostate-specific membrane antigen expression in the vasculature of primary lung carcinomas associates with faster metastatic dissemination to the brain.

Glioblastomas and brain metastases (BM) of solid tumours are the most common central nervous system neoplasms associated with very unfavourable prognosis. In this study, we report the association of prostate-specific membrane antigen (PSMA) with various clinical parameters in a large cohort of primary and secondary brain tumours. A tissue microarray containing 371 cases of ascending grades of gliomas pertaining to astrocytic origin and samples of 52 cases of primary lung carcinomas with matching BM with follow-up time accounting to 10.4 years was evaluated for PSMA expression using immunohistochemistry. In addition, PSMA expression was studied in BM arising from melanomas and breast carcinomas. Neovascular expression of PSMA was evident alongside with high expression in the proliferating microvasculature of glioblastomas when compared to the tumour cell expression. This result correlated with the results obtained from the in silico (cancer genome databases) analyses. In gliomas, only the vascular expression of PSMA associated with poor overall survival but not the tumour cell expression. In the matched primary lung cancers and their BM (n = 52), vascular PSMA expression in primary tumours associated with significantly accelerated metastatic dissemination to the brain with a tendency towards poor overall survival. Taken together, we report that the vascular expression of PSMA in the primary and secondary brain tumours globally associates with the malignant progression and poor outcome of the patients.

The genomic imprint of cancer therapies helps timing the formation of metastases.

A retrospective determination of the time of metastasis formation is essential for a better understanding of the evolution of oligometastatic cancer. This study was based on the hypothesis that genomic alterations induced by cancer therapies could be used to determine the temporal order of the treatment and the formation of metastases. We analysed the whole genome sequence of a primary tumour sample and three metastatic sites derived from autopsy samples from a young never-smoker lung adenocarcinoma patient with an activating EGFR mutation. Mutation detection methods were refined to accurately detect and distinguish clonal and subclonal mutations. In comparison to a panel of samples from untreated smoker or never-smoker patients, we showed that the mutagenic effect of cisplatin treatment could be specifically detected from the base substitution mutations. Metastases that arose before or after chemotherapeutic treatment could be distinguished based on the allele frequency of cisplatin-induced dinucleotide mutations. In addition, genomic rearrangements and late amplification of the EGFR gene likely induced by afatinib treatment following the acquisition of a T790M gefitinib resistance mutation provided further evidence to tie the time of metastasis formation to treatment history. The established analysis pipeline for the detection of treatment-derived mutations allows the drawing of tumour evolutionary paths based on genomic data, showing that metastases may be seeded well before they become detectable by clinical imaging.

JAK-STAT inhibition impairs K-RAS-driven lung adenocarcinoma progression.

Oncogenic K-RAS has been difficult to target and currently there is no K-RAS-based targeted therapy available for patients suffering from K-RAS-driven lung adenocarcinoma (AC). Alternatively, targeting K-RAS-downstream effectors, K-RAS-cooperating signaling pathways or cancer hallmarks, such as tumor-promoting inflammation, has been shown to be a promising therapeutic strategy. Since the JAK-STAT pathway is considered to be a central player in inflammation-mediated tumorigenesis, we investigated here the implication of JAK-STAT signaling and the therapeutic potential of JAK1/2 inhibition in K-RAS-driven lung AC. Our data showed that JAK1 and JAK2 are activated in human lung AC and that increased activation of JAK-STAT signaling correlated with disease progression and K-RAS activity in human lung AC. Accordingly, administration of the JAK1/2 selective tyrosine kinase inhibitor ruxolitinib reduced proliferation of tumor cells and effectively reduced tumor progression in immunodeficient and immunocompetent mouse models of K-RAS-driven lung AC. Notably, JAK1/2 inhibition led to the establishment of an antitumorigenic tumor microenvironment, characterized by decreased levels of tumor-promoting chemokines and cytokines and reduced numbers of infiltrating myeloid derived suppressor cells, thereby impairing tumor growth. Taken together, we identified JAK1/2 inhibition as promising therapy for K-RAS-driven lung AC.

Tumor necrosis correlates with PD-L1 and PD-1 expression in lung adenocarcinoma.

Background: Predictive biomarkers for immunotherapy in lung cancer are intensively investigated; however, correlations between PD-L1/PD-1 expressions and clinical features or histopathological tumor characteristics determined on hematoxylin and eosin stained sections have not extensively been studied. Material and methods: We determined PD-L1 expression of tumor cells (TC) and immune cells (IC), and PD-1 expression of IC by immunohistochemistry in 268 lung adenocarcinoma (LADC) patients, and correlated the data with smoking, COPD, tumor grade, necrosis, lepidic growth pattern, vascular invasion, density of stromal IC, and EGFR/KRAS status of the tumors. Results: There was a positive correlation between PD-L1 expression of TC and IC, as well as PD-L1 and PD-1 expression of IC. Tumor necrosis was associated with higher PD-L1 expression of TC and PD-1 expression of IC. A negative correlation was observed between lepidic growth pattern and PD-L1 expression of TC and PD-L1/PD-1 expression of IC. EGFR mutation seemed to negatively correlate with PD-1 expression of IC, but this tendency could not be verified when applying corrections for multiple comparisons. No significant effect of the KRAS mutation on any of the studied variables could be established. Conclusion: Here we first demonstrate that the presence of necrosis correlates with higher PD-L1 expression of TC and PD-1 expression of IC in LADC. Further studies are required to determine the predictive value of this observation in LADC patients receiving immunotherapy.

Achieving Thoracic Oncology data collection in Europe: a precursor study in 35 Countries.

BACKGROUND: A minority of European countries have participated in international comparisons with high level data on lung cancer. However, the nature and extent of data collection across the continent is simply unknown, and without accurate data collection it is not possible to compare practice and set benchmarks to which lung cancer services can aspire. METHODS: Using an established network of lung cancer specialists in 37 European countries, a survey was distributed in December 2014. The results relate to current practice in each country at the time, early 2015. The results were compiled and then verified with co-authors over the following months. RESULTS: Thirty-five completed surveys were received which describe a range of current practice for lung cancer data collection. Thirty countries have data collection at the national level, but this is not so in Albania, Bosnia-Herzegovina, Italy, Spain and Switzerland. Data collection varied from paper records with no survival analysis, to well-established electronic databases with links to census data and survival analyses. CONCLUSION: Using a network of committed clinicians, we have gathered validated comparative data reporting an observed difference in data collection mechanisms across Europe. We have identified the need to develop a well-designed dataset, whilst acknowledging what is feasible within each country, and aspiring to collect high quality data for clinical research.

[Molecular diagnostics of ALK-positive lung cancer]. / Az ALK-pozitív tüdõrák korszerû diagnosztikája.

ALK translocation is the 3rd most frequent genetic aberration in lung adenocarcinoma, and several inhibitors are now clinically available in first and second line settings. Accordingly, molecular diagnostics of ALK-positive lung cancer is very important and can be done with the rational combination of several methods. All international recommendations suggest that, except for cytological samples, screening technology for ALK-positive tumors is immunohistochemistry using a validated test. It is highly recommended that in case of ALK protein positive samples gene translocation must be confirmed by fluorescent in situ hybridization (FISH). In case of cytological samples FISH technique must be used as ALK diagnostics. In equivocal cases the genetic alteration of ALK can be confirmed by alternative molecular techniques such as next generation sequencing or RNAbased PCR methods. Upon administration of ALK inhibitors, acquired resistance is frequent which is mostly due to ALK amplification and/or mutation. It is evident that the diagnostics of these secondary ALK gene alterations must be done from recurrent tumors or circulating nucleic acids.

Significance of Primary Tumor Location and Histology for Brain Metastasis Development and Peritumoral Brain Edema in Lung Cancer.

BACKGROUND: Brain metastasis of lung cancer adversely affects overall survival (OS) and quality of life, while peritumoral brain edema is responsible for life-threatening complications. METHODS: We retrospectively analyzed the clinicopathological and cerebral radiological data of 575 consecutive lung cancer patients with brain metastases. RESULTS: In adenocarcinoma and squamous cell carcinoma, peritumoral brain edema was more pronounced than in small-cell lung cancer (p < 0.001 and p < 0.001, respectively). There was a positive correlation between the size of metastasis and the thickness of peritumoral brain edema (p < 0.001). It was thicker in supratentorial tumors (p = 0.019), in younger patients (≤50 years) (p = 0.042), and in females (p = 0.016). The time to development of brain metastasis was shorter in central than in peripheral lung cancer (5.3 vs. 9.0 months, p = 0.035). Early brain metastasis was characteristic for adenocarcinomas. A total of 135 patients had brain only metastases (N0 disease) characterized by peripheral lung cancer predominance (p < 0.001) and a longer time to development of brain metastasis (9.2 vs. 4.4 months, p < 0.001). OS was longer in the brain only subgroup than in patients with N1-3 diseases (p < 0.001). CONCLUSIONS: The clinicopathological characteristics of lung cancer are related to the development and radiographic features of brain metastases. Our results might be helpful in selecting patients who might benefit from prophylactic cranial irradiation.

[Self defense instead of offense - Immunotherapy in lung cancer]. / Támadás helyett önvédelem - Immunterápia tüdõrákban.

Lung cancer is the leading cause of cancer death worldwide and also in Hungary, therefore new therapeutic strategies are of great importance. Among immunotherapeutic approaches immune checkpoint inhibition appears to be the most promising. Recent studies have shown efficacy of immunotherapy, especially in squamous cell lung cancer, which is a big step forward in the treatment of this histological subtype. Unlike in the molecularly targeted therapies, the patient selection method has not yet been developed, although some studies indicate the predictive value of tumor cell PD-L1 immunopositivity, especially in lung adenocarcinoma. Introduction of immunotherapy carries challenge for clinicians regarding the radiological assessment of therapeutic efficiency as well as the management of side effects of new profile. The favorable results of recent studies, however, provide hope in this malignancy still presenting a major therapeutic challenge.

[Excerpts from the collaborative lung cancer research program of Semmelweis University, the National Institute of Oncology and Korányi Institute of TB and Pulmonology (2010-2015)]. / Szemelvények a Semmelweis Egyetem, az Országos Onkológiai Intézet és az Országos Korányi Tbc és Pulmonológiai Intézet együttmûködésén alapuló tüdõrák-kutatási programból.

Lung cancer places a significant socio-economic burden on the Hungarian population. This overview summarizes the findings of collaborative translational lung cancer research efforts of three Hungarian flagship academic institutions, the Semmelweis University, the National Institute of Oncology and the National Koranyi Institute of TB and Pulmonology. With regards to the molecular factors regulating tumor angiogenesis, we identified the prognostic significance of apelin and erythropoietin receptor (EPOR) expression in non-small cell lung cancer (NSCLC). Furthermore, the impact of KRAS mutation subtypes and ERCC1 (excision repair cross-complementation group 1) expression on the response to platinum-based chemotherapy have been studied. We also described the epidemiology and predictive power of rare EGFR (epidermal growth factor receptor) mutations in a large Hungarian patient cohort. Lastly, the expression of molecular factors associated with NSCLC progression was studied specifically in brain metastatic matched cases series. These preclinical and clinical studies provide clinically relevant information that hopefully will contribute to the improvement of lung cancer patient care.

[Gefitinib treatment in lung cancer -- rebiopsy, retreatment, remission]. / Rebiopszia és ismételt gefitinibkezeléssel elért remisszió tüdorákban.

The authors present a case of a 81-year-old non-smoker woman who was diagnosed with extended, bilateral bronchial adenocarcinoma in 2008. Two years later the tumor showed marked progression. EGFR sensitizing mutation (exon 19 deletion) was detected and gefitinib treatment was started in March 2010. After 12 months of spectacular and complete remission and 8 months of slow progression docetaxel therapy was applied and yielded partial remission. When progression redeveloped rebiopsy was performed and revealed EGFR exon 19 deletion again. Gefitinib retreatment was introduced in February 2013 and resulted in partial remission with excellent clinical status. In March, 2014 the patient is still on gefitinib treatment without any signs or symptoms of lung cancer but with very slow radiological progression. The authors overview the most important theoretical and practical questions regarding rebiopsy and retreatment in lung cancer with EGFR-TKI therapy.

Are tumor-associated carbohydrates the missing link between the gut microbiome and response to immune checkpoint inhibitor treatment in cancer?

Immune checkpoint inhibitor therapy has dramatically improved survival in a significant subset of patients with several solid tumor types. Increasing the number of patients benefitting from this form of therapy is an important translational research goal. Correlations between the composition of the gut microbiome and response to immune checkpoint inhibitor therapy raised the possibility that direct modulation of the gut microbiome may significantly improve the clinical benefit of this treatment. Several lines of observations suggest that tumor-associated carbohydrates, including those recognized as blood group-related glycolipid antigens, such as the Forssman antigen, may be some of the key factors behind this clinical correlation. Such antigens are expressed in human cancer, humans often produce antibodies against those, and they can induce antibody directed cellular cytotoxicity. Importantly, these antibodies are often induced by antigens present in microbes of the gut. If identified, these antibodies could be boosted by appropriate vaccination techniques and thus enhance anti-tumor immunity with minimal side effects.

Applied models and molecular characteristics of small cell lung cancer.

Small cell lung cancer (SCLC) is a highly aggressive type of cancer frequently diagnosed with metastatic spread, rendering it surgically unresectable for the majority of patients. Although initial responses to platinum-based therapies are often observed, SCLC invariably relapses within months, frequently developing drug-resistance ultimately contributing to short overall survival rates. Recently, SCLC research aimed to elucidate the dynamic changes in the genetic and epigenetic landscape. These have revealed distinct subtypes of SCLC, each characterized by unique molecular signatures. The recent understanding of the molecular heterogeneity of SCLC has opened up potential avenues for precision medicine, enabling the development of targeted therapeutic strategies. In this review, we delve into the applied models and computational approaches that have been instrumental in the identification of promising drug candidates. We also explore the emerging molecular diagnostic tools that hold the potential to transform clinical practice and patient care.

Decreasing incidence and mortality of lung cancer in Hungary between 2011 and 2021 revealed by robust estimates reconciling multiple data sources.

Objective: Hungary has repeatedly been shown to have the highest cancer-related mortality and incidence in Europe. Despite lung cancer being the most abundant malignant diagnosis in Hungary, numerous concerns have been raised recently regarding the bias inherent to reported incidence estimates. Re-analysis of reimbursement claims has been suggested previously by our group as an alternative approach, offering revised figures of lung cancer incidence between 2011 and 2016. Leveraging on this methodology, we aimed at updating Hungarian lung cancer incidence estimates with an additional 5 years (2017-2021), including years affected by the COVID-19 pandemic. Additionally, we also attempted to improve the robustness of estimates by taking additional characteristics of the patient pathway into account. Methods: Lung cancer patients between 2011 and 2021 were identified based on reimbursement-associated ICD-10 codes, histology codes and time patterns. Multiple query architectures were tested for sensitivity and compared to official estimates of the Hungarian National Cancer Registry (HNCR). Epidemiological trends were estimated by Poisson-regression, corrected for age and sex. Results: A total of 89,948 lung cancer patients diagnosed in Hungary between 2011 and 2021 have been identified by our study. In 2019 alone, 7,887 patients were diagnosed according to our optimized query. ESP2013 standardized rate was estimated between 92.5/100,000 (2011) and 78.4/100,000 (2019). In 2019, standardized incidence was 106.8/100,000 for men and 59.7/100,000 for women. Up until the COVID-19 pandemic, lung cancer incidence was decreasing by 3.18% (2.1%-4.3%) yearly in men, while there was no significant decrease in women. Young age groups (40-49 and 50-59) featured the largest improvement, but women aged 60-79 are at an increasing risk for developing lung cancer. The COVID-19 pandemic resulted in a statistically significant decrease in lung cancer incidence, especially in the 50-59 age group (both sexes). Conclusion: Our results show that using an optimized approach, re-analysis of reimbursement claims yields robust estimates of lung cancer incidence. According to this approach, the incidence rate of male lung cancer is declining in Hungary, in concordance with the trend observed for lung cancer mortality. Among women aged 60-79, the incidence of lung cancer has risen, requiring more attention in the near future.

[Analysis of drug therapy of lung cancer in Hungary]. / A tüdorák hazai gyógyszeres kezelésének elemzése.

Hungary is a world leader in lung cancer deaths, so it is particularly important that patients could have access to modern treatments. The aim of our analysis was to find how drug treatments are used in Hungary and how they are compatible with international practice. The in-patient and prescription database of the National Health Insurance Fund for three years (2008-2010) was used to study the frequency of certain chemotherapy protocols, the duration of therapies, and the changes in the individual protocols and drugs used for lung cancer treatment (ICD: C33H0-C34) during the reviewed period. We did not differentiate between neoadjuvant and adjuvant treatment and therapy after progression. During the study period 12326 lung cancer patients received first-line chemotherapy, one third of those (n=3791) received second-line, and one third of those (n=1174) third-line treatment. The average treatment duration was between 3 and 4 months. The first-line treatment of NSCLC mainly consisted of platinum treatment in combination with third generation cytotoxic agents. A downward trend of gemcitabine, still the most common combination compound, was observed, in parallel with the increased use of paclitaxel, and as a consequence carboplatin replaced cisplatin. Among new agents the use of pemetrexed and bevacizumab has increased. Pemetrexed appeared mainly in second-line treatment, while erlotinib also in second, but mostly in third line. The first-line treatment of SCLC consisted of a platinum-etoposide combination, and in second-line setting topotecan was the most commonly used drug. According to our results the chemotherapeutic combinations and sequencing are in accordance with international and national recommendations. Further detailed analysis of the available data may help to obtain more accurate picture of the efficacy of lung cancer treatments as well.

KRASG12C mutant lung adenocarcinoma: unique biology, novel therapies and new challenges.

KRAS mutant lung cancer is the most prevalent molecular subclass of adenocarcinoma (LUAD), which is a heterogenous group depending on the mutation-type which affects not only the function of the oncogene but affects the biological behavior of the cancer as well. Furthermore, KRAS mutation affects radiation sensitivity but leads also to bevacizumab and bisphosphonate resistance as well. It was highly significant that allele specific irreversible inhibitors have been developed for the smoking associated G12C mutant KRAS (sotorasib and adagrasib). Based on trial data both sotorasib and adagrasib obtained conditional approval by FDA for the treatment of previously treated advanced LUAD. Similar to other target therapies, clinical administration of KRASG12C inhibitors (sotorasib and adagrasib) resulted in acquired resistance due to various genetic changes not only in KRAS but in other oncogenes as well. Recent clinical studies are aiming to increase the efficacy of G12C inhibitors by novel combination strategies.

BRAF RNA is prognostic and widely expressed in lung adenocarcinoma.

Background: BRAF is a critical member of proliferation pathways in cancer, and a mutation is present in only 2-4% of lung adenocarcinomas (LADC). There is no data available on the expression pattern of BRAF RNA that might result in enhanced signalling and drug resistance. Methods: LADC tissue samples (n=64) were fixed and processed into paraffin blocks. Tissue microarrays (TMA) were constructed, and RNAScope® in situ hybridization (ISH) assay was performed for wild-type (WT) BRAF RNA. Apart from pathological assessment of tumor samples (grade, necrosis, vascular involvement and peritumoral infiltration), anti-programmed death ligand 1 (PD-L1) and anti-programmed death 1 (PD-1) immunohistochemistry and validation in public databases [The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA)] were carried out. Results: WT BRAF RNA is expressed in LADC, with no significant expressional difference between early-stage (I-II) and advanced-stage (III-IV) patients (P=0.317). Never smokers exhibited significantly increased BRAF expression (compared to current and ex-smokers, P<0.01) and tumor necrosis correlated significantly with BRAF expression (P=0.014). PD-L1 expression was assessed on tumor cells and immune cells, PD-1 expression was evaluated on immune cells. There was no significant difference in BRAF RNA expression between tumor cell PD-L1-high vs. low patients (P=0.124), but it was decreased in immune cell PD-L1-high patients (P=0.03). Kaplan-Meier survival analysis showed that high BRAF expression was associated with significantly decreased OS (P<0.01) and was an independent negative prognostic factor according to multivariate Cox hazard regression (P=0.024). TCGA validation cohort confirmed our findings regarding OS in early-stage patients (P=0.034). Conclusions: We found an increased expression of BRAF RNA in all stages in LADC. High BRAF expression was associated with tumor necrosis, distinct immune checkpoint biology and outcomes. We recommend further evaluating the potential of targeting overexpressed BRAF pathways in LADC.