Non-small cell lung carcinomas with CTNNB1 (beta-catenin) mutations: A clinicopathological study of 26 cases

EGFR status assessment using reflex testing targeted next-generation sequencing for resected non-squamous non-small cell lung cancer

EGFR status assessment is mandatory for adjuvant decision-making of resected stage IB-IIIA non-squamous non-small cell lung cancer (NS-NSCLC). It is questionable whether single-gene RT-PCR versus next-generation sequencing (NGS) should be used for this evaluation. Moreover, co-occurring mutations have an impact on tumor behavior and may influence future therapeutic decision-making. We aimed to describe the clinico-pathological and molecular features, as well as the prognostic factors of resected EGFR-mutant NS-NSCLC evaluated with reflex NGS and RT-PCR, so as to compare the results of the two methods. We retrospectively included and collected data from patients with resected EGFR-mutant NS-NSCLC diagnosed in our institution between 2005 and 2024. Additional cases from another center were included. Tumors were analyzed using targeted NGS and RT-PCR. A total of 153 patients were selected. The median follow-up after surgery was 22 months. The positive percent agreement of RT-PCR compared to NGS for the detection of an EGFR mutation was 88%. Common single EGFR mutations (L858R/del19) were observed in 117/153 (77%) cases; 22/153 (14%) and 14/153 (9%) cases had uncommon single and compound EGFR mutations, respectively. 63/153 (41%) patients had a co-occurring mutation, including a TP53 mutation in 43/63 (68%) co-mutated patients. EGFR/TP53-mutant tumors were associated with positive PD-L1 expression compared to EGFR-mutant/TP53-wild-type tumors (62% vs 39%; p = 0.006). Shorter median event-free survival (EFS) in patients with an EGFR exon 18 mutation and those with TP53 exon 7 co-mutation was recorded. The EGFR status should be systematically evaluated using targeted NGS reflex testing for resected NS-NSCLC since future therapeutic decision-making could soon consider integrating the presence of co-occurring mutations.

Genomic profiling of NSCLC tumors with the TruSight oncology 500 assay provides broad coverage of clinically actionable genomic alterations and detection of known and novel associations between genomic alterations, TMB, and PD-L1

Introduction

Matching patients to an effective targeted therapy or immunotherapy is a challenge for advanced and metastatic non-small cell lung cancer (NSCLC), especially when relying on assays that test one marker at a time. Unlike traditional single marker tests, comprehensive genomic profiling (CGP) can simultaneously assess NSCLC tumors for hundreds of genomic biomarkers and markers for immunotherapy response, leading to quicker and more precise matches to therapeutics.

Methods

In this study, we performed CGP on 7,606 patients with advanced or metastatic NSCLC using the Illumina TruSight Oncology 500 (TSO 500) CGP assay to show its coverage and utility in detecting known and novel features of NSCLC.

Results

Testing revealed distinct genomic profiles of lung adenocarcinoma and squamous cell carcinomas and detected variants with a current targeted therapy or clinical trial in >72% of patient tumors. Known associations between genomic alterations and immunotherapy markers were observed including significantly lower TMB levels in tumors with therapy-associated alterations and significantly higher PD-L1 levels in tumors with ALK, MET, BRAF, or ROS1 driver mutations. Co-occurrence analysis followed by network analysis with gene module detection revealed known and novel co-occurrences between genomic alterations. Further, certain modules of genes with co-occurring genomic alterations had dose-dependent relationships with histology and increasing or decreasing levels of PD-L1 and TMB, suggesting a complex relationship between PD-L1, TMB, and genomic alterations in these gene modules.

Discussion

This study is the largest clinical study to date utilizing the TSO 500. It provides an opportunity to further characterize the landscape of NSCLC using this newer technology and show its clinical utility in detecting known and novel facets of NSCLC to inform treatment decision-making.

Clinical and molecular characteristics associated with high PD-L1 expression in EGFR-mutated lung adenocarcinoma

OBJECTIVE

Recent evidence suggests that elevated levels of PD-L1 expression may be linked to early resistance to TKI and reduced survival in NSCLC with EGFR mutations. This study aimed to characterize the clinical and molecular features of EGFR-mutated lung adenocarcinomas and determine the prognostic significance associated with high PD-L1 expression.

MATERIALS AND METHODS

We conducted a retrospective chart review of 103 consecutive patients with advanced EGFR-mutated NSCLC, who received treatment between 01/01/2016 and 30/12/2020, at our institution.

RESULTS

Among the tumors, 17% (n = 18) exhibited high PD-L1 expression (≥50% tumor proportion score), which was associated with a lower prevalence of common EGFR mutations (56% vs. 82%, p = 0.03) and a higher frequency of complex EGFR mutations (28% vs. 7%, p = 0.02). Univariate analysis did not reveal any significant differences in first-line response, progression-free survival, or overall survival between the PD-L1 ≥50% and <50% groups. However, multivariate analysis demonstrated that PD-L1 ≥50% was independently associated with shorter survival (HR = 2.57; 95%CI[1.20-5.55]; p = 0.02), along with male gender (HR = 2.77; 95%CI[1.54-4.19]; p<0.005), presence of liver metastases (HR = 5.80; 95%CI[2.86-11.75]; p<0.005) or brain metastases (HR = 1.99; 95%CI[1.13-3.52]; p = 0.02), and poor general condition at diagnosis (ECOG 3 and 4) (HR = 10.69; 95% CI[4.42-25.85]; p<0.005). Additionally, a trend towards a higher frequency of de novo resistance was observed in the PD-L1 >50% group (7% vs. 17%, p = 0.19).

CONCLUSION

High PD-L1 expression was more commonly found in lung adenocarcinomas with uncommon and complex EGFR mutations. Furthermore, high PD-L1 expression independently predicted poor survival. These findings warrant validation through prospective studies.

Successful treatment of a non-small-cell lung cancer patient harboring HIP1-ALK (H28:A20) and CTNNB1 p.S45del with alectinib

This is the first case report of a non-small-cell lung cancer (NSCLC) patient harboring HIP1-ALK (H28:A20) and CTNNB1 p.S45del treated with first-line alectinib. Approximately 5% of NSCLC patients are reported to have anaplastic lymphoma kinase (ALK) rearrangements, and among these EML4-ALK is the most frequent fusion variant. However, in recent years the use of next-generation sequencing (NGS) in clinical laboratories has become increasingly widespread, identifying a lot of new ALK fusion partners as well as a large quantity of co-occurring genomic alterations. Unfortunately, the growing number of genomic alterations detected by NGS does not always correspond to adequate knowledge of their clinical significance, often resulting in an empiric treatment of patients harboring uncommon mutations.

Molecular Analysis of Renal/Adrenal Angiosarcomas Reveals High Frequency of Recurrent Genetic Alterations

Angiosarcomas of the kidney and adrenal gland are rare, highly aggressive vascular neoplasms. Their genomic profile has not been systematically studied to date. We report the clinicopathologic and molecular features of six angiosarcomas centered in the kidney/adrenal gland. All patients were male adults, ranging from 58 to 77 years of age. Tumor sizes ranged from 2.5 to 22.5 cm. Half of the cases demonstrated hot spot mutations in the KDR gene, while one-third demonstrated mutations in the PIK3CA gene; both of these gene alterations being previously described, preferentially in breast angiosarcomas. In addition, two cases each demonstrated BRIP1 gene amplification, CTNNB1 and ETV6 mutations, which have not been previously reported in angiosarcoma. Notably, molecular studies were critical in establishing the correct diagnoses in three cases: one was an epithelioid angiosarcoma originally misdiagnosed as metastatic adenocarcinoma to the adrenal gland, the second was a vasoformative angiosarcoma that mimicked hemangioma, and the third was a collision tumor between a high-grade angiosarcoma and a chromophobe renal cell carcinoma which was originally diagnosed as a sarcomatoid renal cell carcinoma. In summary, angiosarcomas of the kidney and adrenal gland have a high frequency of recurrent genetic alterations, some of them being shared with other angiosarcoma subtypes, while other appear to be novel. In particular, activating hot spot KDR and PIK3CA mutations represent potential therapeutic targets for these highly aggressive cancers.

Genomic Landscape of NSCLC in the Republic of Ireland

Introduction

The identification of genomic "targets" through next-generation sequencing (NGS) of patient's NSCLC tumors has resulted in a rapid expansion of targeted treatment options for selected patients. This retrospective study aims to identify the proportion of patients with advanced NSCLC in the Republic of Ireland whose tumors harbor actionable genomic alterations through broad NGS panel testing.

Methods

Institutional review board approval was obtained before study initiation. Patients with NSCLC whose tumors underwent genomic testing through the largest available NGS panel at a nationally funded Cancer Molecular Diagnostics laboratory (St. James's Hospital) between June 2017 and June 2022 were identified. Patient demographics and tumor-related data were collected by retrospective review from all cancer centers in Ireland, referring to the Cancer Molecular Diagnostics laboratory. A total of 203 (9%) tumor samples were excluded due to insufficient neoplastic cell content. Genomic data were collected through retrospective search of Ion Reporter software. The spectrum and proportion of patients with oncogenic driver mutations were evaluated using descriptive statistics (SPSS version 29.0).

Results

In total, 2052 patients were identified. Patients were referred from 23 different hospital sites and all four geographic regions (Leinster = 1091, 53%; Munster = 763, 37.2%; Connacht = 191, 9.3%; Ulster = 7, 0.3%). Median age was 69 (range: 26-94) years; 53% were male. The most common tumor histologic subtype was adenocarcinoma (77%, n = 1577). An actionable genomic alteration was identified in 1099 cases (53%), the most common of which was KRAS (n = 657, 32%). Less frequently, NSCLC tumors harbored the following: MET exon 14 skipping (n = 53, 2.6%), MET amplification (n = 26, 1.3%), EGFR (n = 181, 8.8%), HER2 (n = 35, 1.7%), and BRAF (n = 72, 3.5%) mutations. Fusions were detected in 76 patients (3.7%) including ALK (n = 44, 58%), RET (n = 11, 14.5%), ROS1 (n = 16, 21%), and FGFR3 (n = 5, 6.6%), whereas no NTRK fusion was identified. Co-alterations were detected in 114 patients (5.6%), the most common of which was KRAS/PIK3CA (n = 19, 17%), EGFR/PIK3CA (n = 10, 8.5%), and KRAS/IDH1 (n = 9, 8%). Other co-alterations of interest identified included KRAS G12A/ROS1 fusion (n = 1) and KRAS G12C/BRAF G469A (n = 2).

Conclusions

This is the first retrospective study to comprehensively characterize the genomic landscape of NSCLC in Ireland, using the broadest available NGS panel. Actionable alterations were identified in 53.4% of the patients, and KRAS was the most common oncogenic driver alteration. Our study revealed a lower prevalence of patients whose tumor harbors ALK, ROS1, and RET fusions, compared with similar data sets.

An oncogenic CTNNB1 mutation is predictive of post-operative recurrence-free survival in an EGFR-mutant lung adenocarcinoma

The Wnt/β-catenin pathway is known to be frequently dysregulated in various human malignancies. Alterations in the genes encoding the components of Wnt/β-catenin pathway have also been described in lung adenocarcinoma. Notably however, the clinical impacts of Wnt/β-catenin pathway alterations in lung adenocarcinoma have not been fully evaluated to date. We here investigated the prognostic implications of single gene variations in 174 cases of surgically resected lung adenocarcinoma tested using targeted next-generation sequencing. Screening of the prognostic impact of single gene alterations identified an association between CTNNB1 mutation and poor recurrence-free survival in EGFR-mutant LUADs. Based on these results, the entire cohort was stratified into three groups in accordance with the mutational status of Wnt/β-catenin pathway genes (i.e. oncogenic CTNNB1 mutation [CTNNB1-ONC], other Wnt/β-catenin pathway gene mutations [Wnt/β-catenin-OTHER], and wild type for Wnt/β-catenin pathway genes [Wnt/β-catenin-WT]). The clinicopathologic characteristics and survival outcomes of these groups were then compared. Oncogenic CTNNB1 and other Wnt/β-catenin pathway gene mutations were identified in 10 (5.7%) and 14 cases (8.0%), respectively. The CTNNB1-ONC group cases displayed histopathologic features of conventional non-mucinous adenocarcinoma with no significant differences from those of the other groups. Using β-catenin immunohistochemistry, we found that the CTNNB1-ONC group displayed aberrant nuclear staining more frequently, but only in 60% of the samples. The LUADs harboring a CTNNB1-ONC exhibited significantly poorer RFS outcomes than the other groups, regardless of the β-catenin IHC status. This was a pronounced finding in the EGFR-mutant LUADs only in subgroup analysis, which was then confirmed by multivariate analysis. Nevertheless, no significant OS differences between these Wnt/β-catenin groups were evident. Hence, oncogenic CTNNB1 mutations may be found in about 6% of lung adenocarcinomas and may predict post-operative recurrence in EGFR-mutant LUADs. Aberrant nuclear β-catenin staining on IHC appears to be insufficient as a surrogate marker of an oncogenic CTNNB1 mutation.

The significance of co-mutations in EGFR-mutated non-small cell lung cancer: Optimizing the efficacy of targeted therapies?

Non-small cell lung cancer (NSCLC) is the most common cause of cancer death worldwide. In non-squamous NSCLC, the identification of oncogenic drivers and the development of target-specific molecules led to remarkable progress in therapeutic strategies and overall survival over the last decade. Nevertheless, responses are limited by systematically acquired mechanisms of resistance early on after starting a targeted therapy. Moreover, mounting evidence has demonstrated that each oncogenic-driven cluster is actually heterogeneous in terms of molecular features, clinical behaviour, and sensitivity to targeted therapy. In this review, we aimed to examine the prognostic and predictive significance of oncogene-driven co-mutations, focusing mainly on EGFR and TP53. A narrative review was performed by searching MEDLINE databases for English articles published over the last decade (from January 2012 until November 2022). The bibliographies of key references were manually reviewed to select those eligible for the topic. The genetic landscape of EGFR-mutated NSCLC is more complicated than what is known so far. In particular, the occurrence of TP53 co-mutations stratify patients carrying EGFR mutations in terms of treatment response. The study provides a deeper understanding of the mechanisms underlying the variability of the genetic landscape of EGFR-mutated NSCLC and summarizes notably the clinical importance of TP53 co-mutations for an open avenue to more properly addressing the clinical decision-making in the near future.

A New Wave of Targeting 'Undruggable' Wnt Signaling for Cancer Therapy: Challenges and Opportunities

Aberrant Wnt signaling activation is frequently observed in many cancers. The mutation acquisition of Wnt signaling leads to tumorigenesis, whereas the inhibition of Wnt signaling robustly suppresses tumor development in various in vivo models. Based on the excellent preclinical effect of targeting Wnt signaling, over the past 40 years, numerous Wnt-targeted therapies have been investigated for cancer treatment. However, Wnt signaling-targeting drugs are still not clinically available. A major obstacle to Wnt targeting is the concomitant side effects during treatment due to the pleiotropic role of Wnt signaling in development, tissue homeostasis, and stem cells. Additionally, the complexity of the Wnt signaling cascades across different cancer contexts hinders the development of optimized targeted therapies. Although the therapeutic targeting of Wnt signaling remains challenging, alternative strategies have been continuously developed alongside technological advances. In this review, we give an overview of current Wnt targeting strategies and discuss recent promising trials that have the potential to be clinically realized based on their mechanism of action. Furthermore, we highlight new waves of Wnt targeting that combine recently developed technologies such as PROTAC/molecular glue, antibody-drug conjugates (ADC), and anti-sense oligonucleotides (ASO), which may provide us with new opportunities to target 'undruggable' Wnt signaling.

Papillary thyroid carcinoma with desmoid-type fibromatosis: the clinicopathological features with characteristic imaging and molecular correlation requiring comprehensive treatment

The pathogenesis and treatment of papillary thyroid cancer with desmoid-type fibromatosis (PTC-DTF), a rare subtype of papillary thyroid carcinoma characterized by a mixed epithelial-mesenchymal structure, are still ill-defined. Previous reports on PTC-DTF have had limited follow-up and recurrence has been rarely reported. To better understand this condition, we conducted a thorough analysis of five cases of PTC-DTF from our institute, including clinical and pathological examinations, imaging, immunohistochemistry, and molecular analysis. We also reviewed relevant literature. The mean age of the patients was 51.8 years, with three women and two men included in the group. Ultrasound often showed a hypoechogenic and well-defined nodule in the thyroid gland, except for one individual who had distant lung metastases detected by PET-CT. The nodules ranged in width from 0.5 to 5.0 cm and were excised in each case. Following surgery, ¹³¹I therapy was used in two cases. The overall number of PTC-DTF cases has risen from the previously reported 55 to 60, with females being the most commonly affected and ranging in age from 19 to 82. Most masses underwent a thyroidectomy, and approximately half of the patients had lymph node metastases. Histologically, PTC-DTFs were composed of a predominant stromal component (65% - 90%) and an intervening epithelial component. These spindle cells were arranged in parallel with abundant cytoplasm and vacuole-like nucleus but there wasn't evident atypia. The carcinoma cells were positively stained for CK and TTF-1 by immunohistochemistry, whereas mesenchymal cells were positive for SMA and displayed nuclear immunoreactivity for β-catenin. BRAF, NRAS, and CTNNB1 mutations were identified in the epithelial and mesenchymal components through molecular testing, respectively. Perhaps because the mesenchyme harbors aberrant nuclear β-catenin expression, PTC-DTF is more aggressive and prone to invasion and distant recurrence, as shown by our case 2, which is the first case to be reported thus far. PTC-DTF is typically treated with surgery, but clinicians may occasionally consider more holistic treatment plans that involve radioactive iodine and endocrine therapy.

Non-small cell lung cancer with EGFR (L858R and E709X) and CNNB1 mutations responded to afatinib

Lung cancer with complex epidermal growth factor receptor (EGFR) and CTNNB1 comutations is rare, and the efficacy of tyrosine kinase inhibitors (TKIs) is generally poor. Here, we encountered a lung cancer patient with complex EGFR (L858R and E709X) and CTNNB1 comutations who successfully responded to afatinib. A 78-year-old woman visited our hospital with a cough and bloody sputum that had worsened over the past year. She had multiple mass shadows in both lungs and nodular shadows in the bronchi. The patient was diagnosed with lung adenocarcinoma cT4N3M1c stage IVB. A genetic analysis of the primary tumor using the Oncomine Dx target test multi-CDx system revealed positivity for EGFR (L858R and E709X) and CTNNB1 mutations. The expression of programmed death ligand 1 (22C3 clones) in tumor cells was negative by immunostaining. The patient was treated with afatinib as first-line therapy and achieved clinical improvement and a partial response and is continuing treatment 1 year later. Case reports of lung cancer patients with EGFR/CTNNB1 comutations are rare, and TKIs are not considered to be effective. We herein present the first case report of lung cancer with the co-occurrence of uncommon and complex EGFR (L858R and E709X) and CTNNB1 mutations that was successfully treated with afatinib.

Molecular charcterization of lung adenocarcinoma combining whole exome sequencing, copy number analysis and gene expression profiling

INTRODUCTION

Lung cancer is the leading cause of cancer mortality worldwide; lung adenocarcinoma (LUAD) corresponds to about 40% of lung cancers. LUAD is a genetically heterogeneous disease and the definition of this heterogeneity is of fundamental importance for prognosis and treatment.

AREAS COVERED

Based on primary literature, this review provides an updated analysis of multiomics studies based on the study of mutation profiling, copy number alterations and gene expression allowing for definition of molecular subgroups, prognostic factors based on molecular biomarkers, and identification of therapeutic targets. The authors sum up by providing the reader with their expert opinion on the potentialities of multiomics analysis of LUADs.

EXPERT OPINION

A detailed and comprehensive study of the co-occurring genetic abnormalities characterizing different LUAD subsets represents a fundamental tool for a better understanding of the disease heterogeneity and for the identification of subgroups of patients responding or resistant to targeted treatments and for the discovery of new therapeutic targets. It is expected that a comprehensive characterization of LUADs may provide a fundamental contribution to improve the survival of LUAD patients.

Emerging Molecular Dependencies of Mutant EGFR-Driven Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) mutations are the molecular driver of a subset of non-small cell lung cancers (NSCLC); tumors that harbor these mutations are often dependent on sustained oncogene signaling for survival, a concept known as “oncogene addiction”. Inhibiting EGFR with tyrosine kinase inhibitors has improved clinical outcomes for patients; however, successive generations of inhibitors have failed to prevent the eventual emergence of resistance to targeted agents. Although these tumors have a well-established dependency on EGFR signaling, there remain questions about the underlying genetic mechanisms necessary for EGFR-driven oncogenesis and the factors that allow tumor cells to escape EGFR dependence. In this review, we highlight the latest findings on mutant EGFR dependencies, co-operative drivers, and molecular mechanisms that underlie sensitivity to EGFR inhibitors. Additionally, we offer perspective on how these discoveries may inform novel combination therapies tailored to EGFR mutant NSCLC.

The 2021 WHO Classification of Lung Tumors: Impact of advances since 2015

The 2021 World Health Organisation (WHO) Classification of Thoracic Tumours was published earlier this year, with classification of lung tumors being one of the chapters. The principles remain those of using morphology first, supported by immunohistochemistry and then molecular techniques. In 2015, there was particular emphasis on using immunohistochemistry to make classification more accurate. In 2021, there is greater emphasis throughout the book on advances in molecular pathology across all tumor types. Major features within this edition are 1) broader emphasis on genetic testing than in the 2015 WHO Classification, 2) a chapter entirely dedicated to the classification of small diagnostic samples, 3) continued recommendation to document percentages of histological patterns in invasive non-mucinous adenocarcinomas, with utilization of these features to apply a formal grading system, as well as using only invasive size for T-factor size determination in part lepidic non-mucinous lung adenocarcinomas as recommended by the 8^th Edition TNM Classification, 4) recognition of spread through airspaces (STAS) as a histological feature with prognostic significance, 5) moving lymphoepithelial carcinoma to squamous cell carcinomas, 6) update on evolving concepts in lung neuroendocrine neoplasm classification, 7) recognition of bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT) as a new entity within the adenoma subgroup, 8) recognition of thoracic SMARCA4-deficient undifferentiated tumor, and 9) inclusion of essential and desirable diagnostic criteria for each tumor.

CIRP promotes the progression of non-small cell lung cancer through activation of Wnt/β-catenin signaling via CTNNB1

BACKGROUND

Cold-inducible RNA binding protein (CIRP) is a newly discovered proto-oncogene. In this study, we investigated the role of CIRP in the progression of non-small cell lung cancer (NSCLC) using patient tissue samples, cultured cell lines and animal lung cancer models.

METHODS

Tissue arrays, IHC and HE staining, immunoblotting, and qRT-PCR were used to detect the indicated gene expression; plasmid and siRNA transfections as well as viral infection were used to manipulate gene expression; cell proliferation assay, cell cycle analysis, cell migration and invasion analysis, soft agar colony formation assay, tail intravenous injection and subcutaneous inoculation of animal models were performed to study the role of CIRP in NSCLC cells; Gene expression microarray was used to select the underlying pathways; and RNA immunoprecipitation assay, biotin pull-down assay, immunopurification assay, mRNA decay analyses and luciferase reporter assay were performed to elucidate the mechanisms. The log-rank (Mantel-Cox) test, independent sample T-test, nonparametric Mann-Whitney test, Spearman rank test and two-tailed independent sample T-test were used accordingly in our study.

RESULTS

Our data showed that CIRP was highly expressed in NSCLC tissue, and its level was negatively correlated with the prognosis of NSCLC patients. By manipulating CIRP expression in A549, H460, H1299, and H1650 cell lines, we demonstrated that CIRP overexpression promoted the transition of G1/G0 phase to S phase and the formation of an enhanced malignant phenotype of NSCLC, reflected by increased proliferation, enhanced invasion/metastasis and greater tumorigenic capabilities both in vitro and in vivo. Transcriptome sequencing further demonstrated that CIRP acted on the cell cycle, DNA replication and Wnt signaling pathway to exert its pro-oncogenic action. Mechanistically, CIRP directly bound to the 3'- and 5'-UTRs of CTNNB1 mRNA, leading to enhanced stability and translation of CTNNB1 mRNA and promoting IRES-mediated protein synthesis, respectively. Eventually, the increased CTNNB1 protein levels mediated excessive activation of the Wnt/β-catenin signaling pathway and its downstream targets C-myc, COX-2, CCND1, MMP7, VEGFA and CD44.

CONCLUSION

Our results support CIRP as a candidate oncogene in NSCLC and a potential target for NSCLC therapy.

Single-cell analyses reveal diverse mechanisms of resistance to EGFR tyrosine kinase inhibitors in lung cancer

Tumor heterogeneity underlies resistance to tyrosine kinase inhibitors (TKI) in lung cancers harboring epidermal growth factor receptor (EGFR) mutations. Previous evidence suggested that subsets of preexisting resistant cells are selected by EGFR-TKI treatment, or alternatively, that diverse acquired resistance mechanisms emerge from drug-tolerant persister (DTP) cells. Many studies have used bulk tumor specimens or subcloned resistant cell lines to identify resistance mechanism. However, intratumoral heterogeneity can result in divergent responses to therapies, requiring additional approaches to reveal the complete spectrum of resistance mechanisms. Using EGFR-TKI-resistant cell models and clinical specimens, we performed single-cell RNA-seq and single-cell ATAC-seq analyses to define the transcriptional and epigenetic landscape of parental cells, DTPs, and tumor cells in a fully resistant state. In addition to AURKA, VIM, and AXL, which are all known to induce EGFR-TKI resistance, CD74 was identified as a novel gene that plays a critical role in the drug-tolerant state. In vitro and in vivo experiments demonstrated that CD74 upregulation confers resistance to the EGFR-TKI osimertinib and blocks apoptosis, enabling tumor regrowth. Overall, this study provides new insight into the mechanisms underlying resistance to EGFR-TKIs.

Long-term Outcomes of Oral Vinorelbine in Advanced, Progressive Desmoid Fibromatosis and Influence of CTNNB1 Mutational Status

PURPOSE

Desmoid-type fibromatosis (DF) are locally aggressive neoplasms, with a need for effective systemic treatment in case of progression to avoid the short- and long-term complications of local treatments.

EXPERIMENTAL DESIGN

We retrospectively analyzed the outcomes of adult patients with DF treated with oral vinorelbine (90 mg once weekly) at Gustave Roussy Cancer Institute (Villejuif, Paris, France). Only patients with documented progressive disease according to RECIST v1.1 for more than 3 months (±2 weeks) before treatment initiation were included.

RESULTS

From 2009 to 2019, 90 out of 438 patients with DF were eligible for this analysis. Vinorelbine was given alone in 56 patients (62%), or concomitantly with endocrine therapy in 34 patients, for a median duration of 6.7 months. A partial response was observed in 29% and stable disease in another 57%. With a median follow-up of 52.4 months, the median time to treatment failure (TTF) was not reached. Progression-free rates at 6 and 12 months were 88.7% and 77.5%, respectively. Concomitant endocrine therapy was associated with longer TTF in women [HR, 2.16; 95% confidence interval (CI), 1.06-4.37; P = 0.03). Among 64 patients with documented CTNNB1 mutational status, p.S45F or p.S45P mutations were associated with longer TTF compared with p.T41A or wild-type tumors (HR, 2.78; 95% CI, 1.23-6.27; P = 0.04). Toxicity profile was favorable, without grade 3-4 toxicity, except for one grade 3 neutropenia.

CONCLUSIONS

Oral vinorelbine is an effective, affordable, and well-tolerated regimen in patients with advanced, progressive DF. Prolonged activity was observed in patients with tumors harboring CTNNB1 p.S45F or p.S45P mutations.