MYC Drives Progression of Small Cell Lung Cancer to a Variant Neuroendocrine Subtype with Vulnerability to Aurora Kinase Inhibition

Myc family proteins: Molecular drivers of tumorigenesis and resistance in neuroendocrine tumors

Neuroendocrine cancers are a diverse and poorly understood collection of malignancies derived from neuroendocrine cells throughout the body. These cancers uniquely exhibit properties of both the nervous and endocrine systems. Only a limited number of genetic driver mutations have been identified in neuroendocrine cancers, however the mechanisms of how these genetic aberrations alter tumor biology remain elusive. Recent studies have implicated the MYC family of transcription factors as important oncogenic factors in neuroendocrine tumors. We take a systematic approach to understand the roles of the MYC family (c-MYC, n-MYC, l-MYC) in the tumorigenesis of neuroendocrine cancers of the lung, GI tract, pancreas, kidney, prostate, pediatric neuroblastoma, and adrenal glands. Reflecting the complexity of neuroendocrine cancers, we highlight the roles of the MYC family in deregulating the cell cycle and transcriptional networks, invoking cellular plasticity, affecting proliferation capacity, aiding in chromatin remodeling, angiogenesis, metabolic changes, and resistance mechanisms. Depicting the diversity of neuroendocrine cancers, we suggest new approaches in understanding the underlying tumorigenic processes of neuroendocrine cancers from the perspective of MYC.

Differential susceptibility and role for senescence in CART cells based on costimulatory domains

Despite the success of chimeric antigen receptor T (CART) cell therapy in hematological malignancies, durable remissions remain low. Here, we report CART senescence as a potential resistance mechanism in 41BB-costimulated CART cell therapy. To mimic cancer relapse, we utilized an in vitro model with repeated CART cell activation cycles followed by rest periods. Using CD19-targeted CART cells with costimulation via 4-1BB-CD3ζ (BBζ) or CD28-CD3ζ (28ζ), we showed that CART cells undergo functional, phenotypical, and transcriptomic changes of senescence, which is more prominent in BBζ. We then utilized two additional independent strategies to induce senescence through MYC activation and irradiation. Induction of senescence impaired BBζ activity but improved 28ζ activity in preclinical studies. These findings were supported by analyses of independent patient data sets; senescence signatures in CART cell products were associated with non-response to BBζ but with improved clinical outcomes in 28ζ treatment. In summary, our study identifies senescence as a potential mechanism of failure predominantly in 41BB-costimulated CART cells.

The expression and prognosis for Aurora kinases in human non-small cell lung cancer

BACKGROUND

Aurora kinases (AURKs), members of the serine/threonine kinases gene family, have been implicated in various human cancers, including lung cancer. However, the expression and clinical significance of AURKA, AURKB, and AURKC in non-small cell lung cancer (NSCLC) remain unclear.

METHODS

Comprehensive bioinformatics analyses were conducted using databases such as The Cancer Genome Atlas (TCGA), Gene Expression Profiling Interactive Analysis (GEPIA), and Kaplan-Meier Plotter. Immunohistochemistry (IHC) was performed on tissue microarrays (TMAs) from 29 ‌lung adenocarcinoma (LUAD) patients. AURKA/B knockdown and overexpression cell models were successfully established in LUAD cells. The proliferative capacity of the stable cells was assessed using colony formation assays and CCK-8 assays.

RESULTS

AURKA and AURKB were upregulated in lung cancer tissues compared to normal, while AURKC was downregulated. High expression of AURKA and AURKB was associated with advanced tumor stage and poor survival outcomes in LUAD patients. AURKA and AURKB expression levels correlated with immune cell infiltration and immune checkpoint genes, suggesting potential roles in immunotherapy. In vitro experiments have demonstrated that AURKA and AURKB played crucial roles in promoting proliferation of LUAD cells.

CONCLUSION

This study highlights the prognostic value of AURKA and AURKB in NSCLC, particularly LUAD, and identifies them as potential therapeutic targets or prognostic biomarkers.

Challenges of small cell lung cancer heterogeneity and phenotypic plasticity

Small cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy with ~7% 5-year overall survival reflecting early metastasis and rapid acquired chemoresistance. Immunotherapy briefly extends overall survival in ~15% cases, yet predictive biomarkers are lacking. Targeted therapies are beginning to show promise, with a recently approved delta-like ligand 3 (DLL3)-targeted therapy impacting the treatment landscape. The increased availability of patient-faithful models, accumulating human tumour biobanks and numerous comprehensive molecular profiling studies have collectively facilitated the mapping and understanding of substantial intertumoural and intratumoural heterogeneity. Beyond the almost ubiquitous loss of wild-type p53 and RB1, SCLC is characterized by heterogeneously mis-regulated expression of MYC family members, yes-associated protein 1 (YAP1), NOTCH pathway signalling, anti-apoptotic BCL2 and epigenetic regulators. Molecular subtypes are based on the neurogenic transcription factors achaete-scute homologue 1 (ASCL1) and neurogenic differentiation factor 1 (NEUROD1), the rarer non-neuroendocrine transcription factor POU class 2 homeobox 3 (POU2F3), and immune- and inflammation-related signatures. Furthermore, SCLC shows phenotypic plasticity, including neuroendocrine-to-non-neuroendocrine transition driven by NOTCH signalling, which is associated with disease progression, chemoresistance and immune modulation and, in mouse models, with metastasis. Although these features pose substantial challenges, understanding the molecular vulnerabilities of transcription factor subtypes, the functional relevance of plasticity and cell cooperation offer opportunities for personalized therapies informed by liquid and tissue biomarkers.

Phase separation of RXRγ drives tumor chemoresistance and represents a therapeutic target for small-cell lung cancer

Small-cell lung cancer (SCLC) is the most lethal type of lung cancer, characterized by rapid evolution from chemosensitivity to chemoresistance and limited treatment options. However, the mechanisms underlying this evolution remain poorly understood. Here, we show that Retinoid X receptor γ (RXRγ) is uniquely overexpressed in chemo-resistant SCLC tumors, and that RXRγ serves as an essential factor driving chemoresistance in SCLC. RXRγ forms phase-separated droplets with LSD1 in the nucleus, which enhances RXRγ-mediated gene transcription activity and reprograms gene expression, promoting tumor stemness and metastasis, and eventually driving SCLC chemoresistance. In turn, RXRγ antagonist disrupts RXRγ-LSD1 interaction, reducing their binding to the target gene locus, markedly suppressing the expression of the RXRγ target gene network. Finally, RXRγ antagonists strongly suppress tumor growth and metastasis and restore SCLC vulnerability to chemotherapy in multiple preclinical SCLC models, resulting in a substantial extension of survival in mouse models. Thus, these results establish RXRγ as a key player in SCLC by phase separation and as a potential therapeutic target for this deadly disease.

Molecular subtyping dictates therapeutic response to anti-PD-L1 immunotherapy in ES-SCLC

Anti-PD-L1 immunotherapy is recommended as standard of care for patients with extensive stage small cell lung cancer (ES-SCLC); however, there are no reliable biomarkers guiding patient selection and the survival benefit of PD-L1 inhibitors in the overall population is limited. In this study, we retrospectively analyzed a total number of 61 cases of ES-SCLC who underwent anti-PD-L1 immunotherapy. Patient demographic characteristics and laboratory findings were processed for univariate and multivariate analysis. Subgrouping of SCLC was performed on IHC platform using antibodies against ASCL1, NEUROD1 and POU2F3. The tumor microenvironment (TME) of ES-SCLC was evaluated by CD8 + T cell infiltration, granzyme B production and PD-L1 expression. We found limited efficacy of defined variable factors conferring therapeutic outcomes of anti-PD-L1 immunotherapy in patients with ES-SCLC. Intriguingly, there was a profound difference in TME and response to anti-PD-L1 immunotherapy when classifying SCLC into A/N/P/I subgroups. Although accounted for a small proportion of SCLC, the SCLC-P and SCLC-I subtypes manifested as T cell-enriched "hot" tumor and elicited more favorable response to immunotherapy, whereas the SCLC-A and SCLC-N subgroups were T cell-absent "cold" tumor. There was also a significant difference in progression free survival and overall survival across these subsets. Moreover, we found the SCLC-P and SCLC-I tumors revealed features of low neuroendocrine (NE) differentiation and showed clinicopathologic features overlapping with the SCLC non-NE lineage. These findings may aid clinicians to select ES-SCLC patients who were more likely to gain higher response rate and longer survival to anti-PD-L1 immunotherapy. Revisiting SCLC according to A/N/P/I subtyping and NE/non-NE differentiation is a reliable approach to guide therapeutic strategy in patients with ES-SCLC.

Dopamine D2 receptor agonists abrogate neuroendocrine tumour angiogenesis to inhibit chemotherapy-refractory small cell lung cancer progression

Small cell lung cancer (SCLC) is difficult to treat due to its aggressiveness, early metastasis, and rapid development of resistance to chemotherapeutic agents. Here, we show that treatment with a dopamine D2 receptor (D2R) agonist reduces tumour angiogenesis in multiple in vivo xenograft models of human SCLC, thereby reducing SCLC progression. An FDA-approved D2R agonist, cabergoline, also sensitized chemotherapy-resistant SCLC tumours to cisplatin and etoposide in patient-derived xenograft models of acquired chemoresistance in mice. Ex vivo, D2R agonist treatment decreased tumour angiogenesis through increased apoptosis of tumour-associated endothelial cells, creating a less favourable tumour microenvironment that limited cancer cell proliferation. In paired SCLC patient-derived specimens, D2R was expressed by tumour-associated endothelial cells obtained before treatment, but D2R was downregulated in SCLC tumours that had acquired chemoresistance. D2R agonist treatment of chemotherapy-resistant specimens restored expression of D2R. Activation of dopamine signalling is thus a new strategy for inhibiting angiogenesis in SCLC and potentially for combatting chemotherapy-refractory SCLC progression.

Molecular heterogeneity of small cell lung cancer and new therapeutic possibilities: a narrative review of the literature

Background and Objective

Small cell lung cancer (SCLC) is an aggressive disease commonly occurring in individuals with a history of heavy smoking. Despite recent approvals of chemotherapy and immunotherapy in the first-line treatment of extensive-stage SCLC, it maintains a poor prognosis. Moreover, only a small percentage of patients benefits from the addition of immunotherapy to platinum-based chemotherapy. The lack of significant progress in therapeutic options unrevealed the urgent need for a deeper understanding of tumor biology and easy-to-use predictive biomarkers, aiming to better tailor the treatment strategy. The aim of this review is to summarize recent evidence about the biology, molecular heterogeneity, as well as tumor microenvironment (TME) of SCLC and their forefront therapeutic implications.

Methods

A literature search was conducted using PubMed, focusing on articles published in English from 1981 to October 2024. Studies on SCLC biology and subclassification were selected for further analysis and integrated in the current narrative review.

Key Content and Findings

SCLC entity implies four distinct molecular subtypes based on transcription factors expression, specifically achaete-scute homolog 1 (ASCL1), neurogenic differentiation 1 (NEUROD1), POU class 2 homeobox 3 (POU2F3), and yes-associated protein 1 (YAP1), reflecting the tumor heterogeneity in terms of gene expression, transcriptional profiles, immune infiltration, and treatment sensitivity. Recently, a new subgroup, "SCLC-I", has been proposed to replace the YAP1 subtype, showing higher responsiveness to immunotherapy. The TME, implying immune cell infiltration and their interactions with cancer cells, plays a crucial role in determining SCLC's sensitivity to immunotherapy.

Conclusions

Advances in SCLC molecular characterization and the development of targeted therapies against specific molecular pathways might improve patients' clinical outcome, supporting a more personalized approach to this complex disease.

mTOR-mediated p62/SQSTM1 stabilization confers a robust survival mechanism for ovarian cancer

Over 50 % of patients with high-grade serous carcinoma (HGSC) are homologous recombination proficient, making them refractory to platinum-based drugs and poly (ADP-ribose) polymerase (PARP) inhibitors. These patients often develop progressive resistance within 6 months after primary treatment and tend to die early, thus new therapies are urgently needed. In this study, we comprehensively investigated this tumor type by leveraging a combination of machine learning analysis of a large published dataset and newly developed genetically engineered HGSC organoid models from murine fallopian tubes. Aberrant activation of RAS/PI3K signaling was a signature of poor prognosis in BRCA1/2 wild-type ovarian cancer, and mTOR-induced elevated p62 expression was a robust marker of chemotherapy-induced mTOR-p62-NRF2 signal activation. mTOR inhibition with everolimus decreased p62 and enhanced sensitivity to conventional chemotherapy, indicating that p62 serves as an important biomarker for therapeutic intervention. Combination therapy with conventional chemotherapy and mTOR inhibitors is a promising therapeutic strategy for refractory HGSC, with p62 as a biomarker.

In vivo functional screens reveal KEAP1 loss as a driver of chemoresistance in small cell lung cancer

Exquisitely chemosensitive initially, small cell lung cancer (SCLC) exhibits dismal outcomes owing to rapid transition to chemoresistance. Elucidating the genetic underpinnings has been challenging owing to limitations with cellular models. As SCLC patient-derived xenograft (PDX) models mimic therapeutic responses, we perform genetic screens in chemosensitive PDX models to identify drivers of chemoresistance. cDNA overexpression screens identify MYC, MYCN, and MYCL, while CRISPR deletion screens identify KEAP1 loss as driving chemoresistance. Deletion of KEAP1 switched a chemosensitive SCLC PDX model to become chemoresistant and resulted in sensitivity to inhibition of glutamine metabolism. Data from the IMpower133 clinical trial revealed ~6% of patients with extensive-stage SCLC exhibit KEAP1 genetic alterations, with activation of a KEAP1/NRF2 transcriptional signature associated with reduced survival upon chemotherapy treatment. While roles for KEAP1/NRF2 have been unappreciated in SCLC, our genetic screens revealed KEAP1 loss as a driver of chemoresistance, while patient genomic analyses demonstrate clinical importance.

Molecular Subtypes and Targeted Therapeutic Strategies in Small Cell Lung Cancer: Advances, Challenges, and Future Perspectives

Small cell lung cancer (SCLC) is a highly aggressive malignancy characterized by rapid progression, early metastasis, and high recurrence rates. Historically considered a homogeneous disease, recent multi-omic studies have revealed distinct molecular subtypes driven by lineage-defining transcription factors, including ASCL1, NEUROD1, POU2F3, and YAP1, as well as an inflamed subtype (SCLC-I). These subtypes exhibit unique therapeutic vulnerabilities, thereby paving the way for precision medicine and targeted therapies. Despite recent advances in molecular classification, tumor heterogeneity, plasticity, and therapy resistance continue to hinder clinical success in treating SCLC patients. To this end, novel therapeutic strategies are being explored, including BCL2 inhibitors, DLL3-targeting agents, Aurora kinase inhibitors, PARP inhibitors, and epigenetic modulators. Additionally, immune checkpoint inhibitors (ICIs) show promise, particularly in immune-enriched subtypes of SCLC patients. Hence, a deeper understanding of SCLC subtype characteristics, evolution, and the regulatory mechanisms of subtype-specific transcription factors is crucial for rationally optimizing precision therapy. This knowledge not only facilitates the identification of subtype-specific therapeutic targets, but also provides a foundation for overcoming resistance and developing personalized combination treatment strategies. In the future, the integration of multi-omic data, dynamic molecular monitoring, and precision medicine approaches are expected to further advance the clinical translation of SCLC subtype-specific therapies, ultimately improving patient survival and outcomes.

Clinical Impact of POU2F3 Expression in Surgically Resected Pulmonary High-Grade Neuroendocrine Carcinoma

OBJECTIVE

 High-grade neuroendocrine carcinoma (HGNEC) with dominant POU2F3 expression exhibits non-neuroendocrine features. However, clinical data regarding this subset of pulmonary HGNECs are scarce, and its clinical characteristics remain unclear.

METHODS

 Clinicopathological data from 109 patients who underwent surgery for HGNEC were collected and analyzed based on transcription factor expression. Patients were divided into a POU2F3-dominant group (HGNEC-P) and a non-dominant group (HGNEC-non-P) according to immunohistochemical analysis. The clinicopathological characteristics of the two groups were compared, and univariate and multivariate analyses were conducted to identify prognostic factors.

RESULTS

 The HGNEC-P group comprised 26 patients, while the HGNEC-non-P group comprised 83 patients. The HGNEC-P group showed significantly lower expression of carcinoembryonic antigen (CEA) (p < 0.001) and a lower rate of vascular invasion (p = 0.021) compared to the HGNEC-non-P group. In addition, the HGNEC-P group exhibited a unique tumor marker profile, with lower serum CEA and higher serum cytokeratin antigen (CYFRA) levels (p < 0.001 and p = 0.046, respectively). Complete resection was achieved in all HGNEC-P cases, whereas only 75.9% of HGNEC-non-P cases achieved complete resection. Multivariate analysis identified POU2F3 expression as an independent prognostic factor for recurrence-free survival (RFS) and disease-specific survival (DSS) (p = 0.037 and p = 0.038, respectively). In patients with pathological Stage I disease, the HGNEC-P group showed significantly better RFS (p = 0.010).

CONCLUSIONS

 POU2F3-dominant HGNEC is associated with distinct clinicopathological features and favorable prognosis, particularly in early-stage disease. These findings may support the identification of this subset and inform the development of more effective treatment strategies.

Comparative profiling of surgically resected primary tumors and their lymph node metastases in small-cell lung cancer

BACKGROUND

Profiling studies in small-cell lung cancer (SCLC) have mainly focused on primary tumors, omitting the potential molecular changes that might occur during lymphatic metastasis formation. Here, we assessed the molecular discordance between primary SCLCs and corresponding lymph node (LN) metastases in the light of subtype distribution and expression of clinically relevant proteins.

METHODS

Comparative profiling of 32 surgically resected primary SCLCs and their LN metastases was achieved by RNA expression analysis and immunohistochemistry (IHC). In addition to subtype markers (ASCL1, NEUROD1, POU2F3, and YAP1), the expression of nine cancer-specific proteins was evaluated.

RESULTS

The selected clinically relevant molecules showed no significant differences in their RNA expression profile when assessing the primary tumors and their corresponding LN metastases. Nevertheless, IHC analyses revealed significantly higher DLL3 expression in the primary tumors than in the LN metastases (P = 0.008). In contrast, NEUROD1 expression was significantly lower in the primary tumors (versus LN metastases, P < 0.001). No statistically significant difference was found by IHC analysis in the case of other clinically relevant proteins. Concerning SCLC molecular subtypes, a change in subtype distribution was detected in 21 cases. Phenotype switching from neuroendocrine (NE) subtypes toward non-NE lesions and from non-NE landscape toward NE subtypes were both detected.

CONCLUSIONS

Although the molecular landscape of SCLC LN metastases largely resembles that of the tumor of origin, key differences exist in terms of DLL3 and NEUROD1 expression, and in subtype distribution. These diagnostic pitfalls should be considered when establishing the tumors' molecular profile for future clinical trials solely based on LN biopsies.

Current and future therapies for small cell lung carcinoma

Small cell lung cancer (SCLC) is an aggressive malignancy characterized by rapid proliferation and high metastatic potential. It is characterized by universal inactivation of and RB1, overexpression of the MYC family and dysregulation of multiple oncogenic signaling pathways. Among different patients, SCLCs are similar at the genetic level but exhibit significant heterogeneity at the molecular level. The classification of SCLC has evolved from a simple neuroendocrine (NE)/non-neuroendocrine (non-NE) classification system to a transcription factor-based molecular subtype system; lineage plasticity adds further complexity and poses challenges for therapeutic development. While SCLC is initially sensitive to platinum-based chemotherapy, resistance develops rapidly, leading to a dismal prognosis. Various antibodies, including PD-1/PD-L1 inhibitors and antibody‒drug conjugates, have been introduced into clinical practice or are being evaluated in clinical trials. However, their therapeutic benefits for SCLC patients remain limited. This review summarizes SCLC carcinogenic mechanisms, tumor heterogeneity, and the immune microenvironment of SCLC, with a focus on recent advances in metastasis and resistance mechanisms. Additionally, the corresponding clinical progress in tackling these challenges is discussed.

Multiple Kinase Small Molecule Inhibitor Tinengotinib (TT-00420) Alone or With Chemotherapy Inhibit the Growth of SCLC

There is an urgent need to develop new targeted treatment agents for small cell lung cancer (SCLC). Tinengotinib (TT-00420) is a novel, multi-targeted, and spectrally selective small-molecule kinase inhibitor that has shown significant inhibitory effects on certain solid tumors in preclinical studies. However, its role and mechanism of action in SCLC remain unclear. In this study, we demonstrated that tinengotinib effectively inhibited SCLC cell proliferation, especially highly expressing NeuroD1 (SCLC-N), in the SCLC cell line-derived xenograft (CDX) model and the malignant pleural effusion cell model of patients with SCLC. When combined with etoposide/cisplatin, it synergistically inhibited SCLC growth. Tinengotinib regulates proliferation, apoptosis, migration, cell cycle and angiogenesis in SCLC cells. Mechanistic studies revealed that c-Myc expression may be a key factor influencing the effect of tinengotinib in SCLC-N. This study provides reliable preclinical data and a new direction for tinengotinib as a promising therapy for SCLC, either alone or in combination with chemotherapy.

Advances in adoptive cell therapies in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive tumor characterized by early metastasis and resistance to treatment, making it a prime target for therapeutic investigation. The current standard of care for frontline treatment involves a combination of chemotherapeutic agents and immune checkpoint inhibitors (ICIs), though durability of response remains limited. The genetic heterogeneity of SCLC also complicates the development of new therapeutic options. Adoptive cell therapies show promise by targeting specific mutations in order to increase efficacy and minimize toxicity. There has been significant investigation in three therapeutic classes for application towards SCLC: antibody drug conjugates (ADCs), bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR)-T cell therapies. This review summarizes the recent advances and challenges in the development of adoptive cell therapies. Genetic targets such as delta-like ligand 3 (DLL3), trophoblast cell surface antigen 2 (Trop2), B7-H3 (CD276), gangliosides disialoganglioside GD2 (GD2) and ganglioside GM2 (GM2) have been found to be expressed in SCLC, which makes them prime targets for therapy development. While investigated therapies such as rovalpituzumab tesirine (Rova-T) have failed, several insights from these trials have led to the development of compelling new agents such as sacituzumab govitecan (SG), ifinatamab deruxtecan (I-DXd), tarlatamab, and DLL3-targeted CAR-T cells. Advancing development of molecular testing and improving targeted approaches remain integral to pushing forward the progress of adoptive cell therapies in SCLC.

Intercellular signaling reinforces single-cell level phenotypic transitions and facilitates robust re-equilibrium of heterogeneous cancer cell populations

Background

Cancer cells within tumors exhibit a wide range of phenotypic states driven by non-genetic mechanisms in addition to extensively studied genetic alterations. Conversions among cancer cell states can result in intratumoral heterogeneity which contributes to metastasis and development of drug resistance. However, mechanisms underlying the initiation and/or maintenance of such phenotypic plasticity are poorly understood. In particular, the role of intercellular communications in phenotypic plasticity remains elusive.

Methods

In this study, we employ a multiscale inference-based approach using single-cell RNA sequencing (scRNA-seq) data to explore how intercellular interactions influence phenotypic dynamics of cancer cells, particularly cancers undergoing epithelial-mesenchymal transition. In addition, we use mathematical models based on our data-driven findings to interrogate the roles of intercellular communications at the cell populations from the viewpoint of dynamical systems.

Results

Our inference approach reveals that signaling interactions between cancerous cells in small cell lung cancer (SCLC) result in the reinforcement of the phenotypic transition in single cells and the maintenance of population-level intratumoral heterogeneity. Additionally, we find a recurring signaling pattern across multiple types of cancer in which the mesenchymal-like subtypes utilize signals from other subtypes to support its new phenotype, further promoting the intratumoral heterogeneity. Our models show that inter-subtype communication both accelerates the development of heterogeneous tumor populations and confers robustness to their steady state phenotypic compositions.

Conclusions

Our work highlights the critical role of intercellular signaling in sustaining intratumoral heterogeneity, and our approach of computational analysis of scRNA-seq data can infer inter- and intra-cellular signaling networks in a holistic manner.

Tuft cells transdifferentiate to neural-like progenitor cells in the progression of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is partly initiated through the transdifferentiation of acinar cells to metaplasia, which progresses to neoplasia and cancer. Tuft cells (TCs) are chemosensory cells not found in the normal pancreas but arise in cancer precursor lesions and diminish during progression to carcinoma. These metaplastic TCs (mTCs) suppress tumor progression through communication with the tumor microenvironment, but their fate during progression is unknown. To determine the fate of mTCs during PDA progression, we created a dual recombinase lineage trace model, wherein a pancreas-specific FlpO was used to induce tumorigenesis, while a tuft-cell specific Pou2f3CreERT/+ driver was used to induce expression of a tdTomato reporter. We found that mTCs in carcinoma transdifferentiate into neural-like progenitor cells (NRPs), a cell type associated with poor survival in patients. Using conditional knockout and overexpression systems, we found that Myc activity in mTCs is necessary and sufficient to induce this tuft-to-neuroendocrine transition (TNT).

Identification of methionine metabolism related prognostic model and tumor suppressive functions of BHMT in hepatocellular carcinoma

Given the resistance to conventional treatments and limitations of immune checkpoint blockade therapy in hepatocellular carcinoma (HCC), it is imperative to explore novel prognostic models and biomarkers. The dependence of cancer cell on exogenous methionine, known as Hoffman effect, is a hallmark of HCC, with numerous studies reporting a strong correlation between methionine metabolism and tumor development. Betaine-homocysteine S-methyltransferase (BHMT), a critical component of methionine metabolism pathway, has polymorphisms linking to poor prognosis in multiple cancers. Nevertheless, there is little literature regarding the relationship between methionine metabolism and incidence, mortality of HCC, as well as the function of BHMT in HCC progression. In this study, by analyzing multiple datasets, we constructed a methionine metabolism-related prognostic model and thoroughly investigated the influence of BHMT on the prognosis of HCC. Bioinformatics analysis revealed a marked decrease in BHMT expression in HCC, which was linked to adverse clinical outcomes. CIBERSORT results suggest that BHMT promotes infiltration of M1 macrophages. Our results suggest its potential as an ideal prognostic biomarker for anti PD-L1 immunotherapy. In summary, this study innovatively provides first methionine metabolism-related prognostic model and unveils the tumor suppressive function of BHMT in HCC, providing potential mechanism by which BHMT exert its function.

Lethal co-expression intolerance underlies the mutually exclusive expression of ASCL1 and NEUROD1 in SCLC cells

Small cell lung cancer (SCLC) subtypes, defined by the expression of lineage-specific transcription factors (TFs), are thought to be mutually exclusive, with intra-tumoral heterogeneities. This study investigated the mechanism underlying this phenomenon with the aim of identifying a novel vulnerability of SCLC. We profiled the expression status of ASCL1, NEUROD1, POU2F3, and YAP1 in 151 surgically obtained human SCLC samples. On subtyping, a high degree of mutual exclusivity was observed between ASCL1 and NEUROD1 expression at the cell, but not tissue, level. Inducible co-expression models of all combinations of ASCL1, NEUROD1, POU2F3, YAP1, and ATOH1 using SCLC cell lines showed that some expression combinations, such as ASCL1 and NEUROD1, exhibited mutual repression and caused growth inhibition and apoptosis. Gene expression and ATAC-seq analyses of the ASCL1 and NEUROD1 co-expression models revealed that co-expression of ASCL1 in NEUROD1-driven cells, and of NEUROD1 in ASCL1-driven cells, both (although more efficiently by the former) reprogrammed the cell lineage to favor the ectopically expressed factor, with rewiring of chromatin accessibility. Mechanistically, co-expressed NEUROD1 in ASCL1-driven SCLC cells caused apoptosis by downregulating BCL2, likely in a MYC-independent manner. In conclusion, lethal co-expression intolerance underlies the mutual exclusivity between these pioneer TFs, ASCL1 and NEUROD1, in an SCLC cell. Further investigation is warranted to enable therapeutic targeting of this vulnerability.

Targeting FOXP1 phase separation in small cell lung cancer mechanisms of chemotherapy resistance

Our study elucidates the role of FOXP1 in chemoresistance in small cell lung cancer(SCLC). FOXP1 enhances chemoresistance by regulating SP8 expression through its super-enhancer (SP8-SE), with SP8 mediating resistance via the homologous recombination repair (HRR) pathway. We also discovered that FOXP1 forms punctate nuclear structures indicative of liquid-liquid phase separation, crucial for its transcriptional regulation. Targeting the FOXP1-SP8-HR axis with BRD4 and PARP inhibitors showed synergistic effects in reducing tumor growth in vitro and in patient-derived xenograft models. These findings identify FOXP1 as a critical mediator and marker of chemoresistance in SCLC, providing a foundation for developing targeted therapies to overcome this resistance.

KLF4 promotes a KRT13+ hillock-like state in squamous lung cancer

Lung squamous cell carcinoma (LUSC) is basal-like subtype of lung cancer with limited treatment options. While prior studies have identified tumor-propagating cell states in squamous tumors, the broader landscape of intra-tumoral heterogeneity within LUSC remains poorly understood. Here, we employ Sox2-driven mouse models, organoid cultures, and single-cell transcriptomic analyses to uncover previously unrecognized levels of cell fate diversity within LUSC. Specifically, we identify a KRT13+ hillock-like population of slower-dividing tumor cells characterized by immunomodulatory gene expression signatures. The tumor hillock-like state is conserved across multiple animal models and is present in the majority of human LUSCs as well as head and neck and esophageal squamous tumors. Our findings shed light on the cellular origins of lung hillock-like states: normal club cells give rise to tumors with luminal hillock-like populations, while basal-like tumor-propagating cells transition into basal hillock-like states, resembling homeostatic cellular responses to lung injury. Mechanistically, we identify KLF4 as a key transcriptional regulator of the hillock-like state, both necessary and sufficient to induce KRT13 expression. Together, these results provide new molecular insights into cell fate plasticity that underlies intra-tumoral heterogeneity in LUSC, offering potential avenues for new therapeutic strategies.

Partial transformation from non-small cell lung cancer to small cell lung cancer: a case report and literatures review

A fraction of lung adenocarcinoma patients with gene mutations who receive targeted therapy would experience acquired resistance and undergo small cell lung cancer (SCLC) transformation. The mechanisms behind the transformation of tumor pathological types and the treatment strategies are not fully clear. There have been case reports of the transformation from adenocarcinoma to SCLC, but the partial transformation from adenocarcinoma to SCLC has not been reported. We reported a case of a patient with partial transformation from lung adenocarcinoma to SCLC for the first time. The patient was diagnosed as lung adenocarcinoma with epidermal growth factor receptor (EGFR) 19 exon mutation and Tumor protein p53 (TP53) mutation. She received Epithelial growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) treatment. However, the tumor progression occurred and the lung aspiration pathology revealed a transformation from non-small cell lung cancer (NSCLC) to SCLC. The treatment regimen was changed to cisplatin and etoposide (EP) chemotherapy, resulting in a 2-month PFS. It was worth mentioning that adenocarcinoma cells were found in the patient's emerging pericardial effusion, suggesting the co-existence of both adenocarcinoma and SCLC components. This is the first report of partial transformation from NSCLC to SCLC in the context of definitive pathology. It highlights that when no more pathological biopsy is feasible, we should be alert to the partial transformation and adopt the appropriate treatment.

Sympathetic Neurons Promote Small Cell Lung Cancer through the β2-Adrenergic Receptor

SIGNIFICANCE

SCLC is highly aggressive, with limited effective treatment options. We show that ablating sympathetic nerves or inhibiting the ADRB2 receptor slows SCLC progression and prolongs survival in mice. Additionally, ADRB2 inhibition reduces the growth of human SCLC organoids and xenografts by disrupting PKA signaling, identifying a new therapeutic target.

Intrinsic electrical activity drives small-cell lung cancer progression

Elevated or ectopic expression of neuronal receptors promotes tumour progression in many cancer types1,2; neuroendocrine (NE) transformation of adenocarcinomas has also been associated with increased aggressiveness3. Whether the defining neuronal feature, namely electrical excitability, exists in cancer cells and impacts cancer progression remains mostly unexplored. Small-cell lung cancer (SCLC) is an archetypal example of a highly aggressive NE cancer and comprises two major distinct subpopulations: NE cells and non-NE cells4,5. Here we show that NE cells, but not non-NE cells, are excitable, and their action potential firing directly promotes SCLC malignancy. However, the resultant high ATP demand leads to an unusual dependency on oxidative phosphorylation in NE cells. This finding contrasts with the properties of most cancer cells reported in the literature, which are non-excitable and rely heavily on aerobic glycolysis. Additionally, we found that non-NE cells metabolically support NE cells, a process akin to the astrocyte-neuron metabolite shuttle6. Finally, we observed drastic changes in the innervation landscape during SCLC progression, which coincided with increased intratumoural heterogeneity and elevated neuronal features in SCLC cells, suggesting an induction of a tumour-autonomous vicious cycle, driven by cancer cell-intrinsic electrical activity, which confers long-term tumorigenic capability and metastatic potential.

Genomic alterations and transcriptional phenotypes in circulating free DNA and matched metastatic tumor

BACKGROUND

Profiling circulating cell-free DNA (cfDNA) has become a fundamental practice in cancer medicine, but the effectiveness of cfDNA at elucidating tumor-derived molecular features has not been systematically compared to standard single-lesion tumor biopsies in prospective cohorts of patients. The use of plasma instead of tissue to guide therapy is particularly attractive for patients with small cell lung cancer (SCLC), due to the aggressive clinical course of this cancer, which makes obtaining tumor biopsies exceedingly challenging.

METHODS

In this study, we analyzed a prospective cohort of 49 plasma samples obtained before, during, and after treatment from 20 patients with recurrent SCLC. We conducted cfDNA low-pass whole genome sequencing (0.1X coverage), comparing it with time-point matched tumor characterized using whole-exome (130X) and transcriptome sequencing.

RESULTS

A direct comparison of cfDNA and tumor biopsy revealed that cfDNA not only mirrors the mutation and copy number landscape of the corresponding tumor but also identifies clinically relevant resistance mechanisms and cancer driver alterations not detected in matched tumor biopsies. Longitudinal cfDNA analysis reliably tracks tumor response, progression, and clonal evolution. Sequencing coverage of plasma DNA fragments around transcription start sites showed distinct treatment-related changes and captured the expression of key transcription factors such as NEUROD1 and REST in the corresponding SCLC tumors. This allowed for the prediction of SCLC neuroendocrine phenotypes and treatment responses.

CONCLUSIONS

cfDNA captures a comprehensive view of tumor heterogeneity and evolution. These findings have significant implications for the non-invasive stratification of SCLC, a disease currently treated as a single entity.

Genomic Profiling of Extensive Stage Small-Cell Lung Cancer Patients Identifies Molecular Factors Associated with Survival

Objective

Extensive stage Small-Cell Lung Cancer (ES-SCLC) is the most lethal lung cancer, and the addition of immunotherapy conferred a slight survival benefit for patients. Extensive molecular profiling of patients treated with chemotherapy (CT) or chemotherapy plus immunotherapy (CT+IO) would be able to identify molecular factors associated with patients' survival.

Material and Methods

In this retrospective study, 99 ES-SCLC patients were considered. Of the 79 includible patients, 42 received CT (median age 71 y/o, I-IIIQ: 65-76), and 37 received CT+IO (median age 71 y/o, I-IIIQ 66-75). The FoundationOne CDx assay was performed on patients' tumor tissues.

Results

The most mutated genes were TP53 (99%), RB1 (78%), PTEN (23%) and MLL2 (20%), with no significant differences between the treatment groups. As a continuous variable, Tumor Mutation Burden (TMB) had an effect on patients' progression-free survival (PFS) by type of treatment (HR 1.81 (95%, CI: 0.99-3.31) and HR 0.84 (95%, CI: 0.56-1.26) for patients treated with CT and CT+IO, respectively). TMB was also computed and dichotomized using two different cut-offs: considering cut-offs of 10 mut/Mb and >16 mut/Mb, 45 patients (57%) and 68 patients (86.1%) had a low TMB, respectively. A high TMB (cut-off 10 mut/Mb) predicted worse PFS in patients treated with CT (p=0.046); even though not statistically significant, a high TMB (cut-off 16 mut/Mb) predicted a better survival in patients treated with CT+IO. Moreover, at univariate analysis, MLL2 mutations were associated with better prognosis in the overall case series (HRPFS = 0.51, 95% CI: 0.28-0.94), and overall survival (HROS = 0.52, 95% CI: 0.28-0.97).

Conclusion

In ES-SCLC, TMB is associated with worse survival in patients treated with CT alone, and with better survival in patients treated with CT+IO, whether considered as a continuous or a dichotomized variable, at different cut-offs. Alterations in epigenetic factors are also associated to better patient prognosis.

Deep analysis of the trials and major challenges in the first-line treatment for patients with extensive-stage small cell lung cancer

The median overall survival (OS) is approximately 10 months when chemotherapy alone is the first-line treatment for extensive-stage small cell lung cancer (ES-SCLC). The approval of the two PD-L1 inhibitors, atezolizumab and durvalumab, marked the beginning of the immunotherapy era for ES-SCLC. Serplulimab, as the first PD-1 inhibitor to achieve success in the first-line treatment of ES-SCLC, has not only demonstrated significant improvements in patient survival outcomes but also ushered in a new era for PD-1 inhibitors in the treatment of ES-SCLC. Recently, antiangiogenic agents with chemo-immunotherapy have achieved breakthroughs in first-line ES-SCLC treatment. Improving the clinical benefits of individualized treatment for patients with ES-SCLC remains challenging. Challenges include identifying biomarkers for targeted therapy, exploring new treatments, developing new medicines, and classifying SCLC molecular subtypes. This review provides an in-depth analysis of research on first-line ES-SCLC treatment. Additionally, it discusses advances in ES-SCLC treatment.

Identification of a Potent and Selective CDK9 Degrader as a Targeted Therapeutic Option for the Treatment of Small-Cell Lung Cancer

Small-cell lung cancer (SCLC) represents a significant public health challenge due to its increasing incidence and high mortality. Most SCLC patients are diagnosed at advanced stages, and there are limited effective targeted therapies available. In this study, a potent and selective CDK9 degrader, C3, was developed through PROTAC modification of the CDK9 inhibitor, AT-7519. C3 effectively induced apoptosis in various SCLC cell lines at low nanomolar concentrations and demonstrated favorable in vivo tolerance and adequate oral bioavailability. Notably, PROTAC C3 significantly reduced the proliferation of primary tumor samples from patients in mini-PDX models. Our findings indicate that the targeted degradation of CDK9 could become a viable strategy for treating SCLC, highlighting its potential therapeutic value. Additionally, this research offers a general structural optimization and evaluation strategy to improve the degradative selectivity, metabolic stability, and oral availability of PROTAC molecules.

Heterogeneity of molecular subtyping and therapy-related marker expression in primary tumors and paired lymph node metastases of small cell lung cancer

The classification of molecular subtypes and the identification of targetable molecules have been proposed for small cell lung cancer (SCLC) patients. Our aim was to investigate whether the expression of these markers evaluated using lymph node (LN) metastases represents that of primary tumors. We enrolled 46 surgically resected SCLC patients' primary tumors and paired mediastinal LN metastases. The protein expression of subtype-defining markers (ASCL1, NEUROD1, POU2F3, and YAP1) and therapeutic markers (DLL3, MYC, PD-L1, and MHC I) was examined by immunohistochemistry and was correlated with clinicopathological parameters and prognoses. In primary and metastatic tumors, the expression of these markers was 78.3% and 87.0%, 50.0% and 63.0%, 13.0% and 6.5%, 17.4% and 15.2%, 84.8% and 87.0%, 17.4% and 6.5%, 50.0% and 34.8%, and 60.9% and 37.0%, respectively. Positive tumor PD-L1 expression was less present in LN metastases (p = 0.015), and the same was true for MHC I expression (p = 0.036). NEUROD1 and DLL3 expression levels in metastatic tumors were stronger (p < 0.001 and p = 0.002, respectively); conversely, POU2F3, MYC, PD-L1, and MHC I expression levels were weaker (p = 0.018, p = 0.019, p = 0.001, and p < 0.001, respectively). In 15 (32.6%) patients, we observed a change in the molecular subtyping pattern, and a higher number of neuroendocrine (NE)-high phenotype patients were diagnosed when using the LN specimens (91.3% vs. 84.8%). TNM stage and postoperative chemotherapy were independent prognostic factors in surgically resected SCLC patients, and no prognostic differences were found among molecular subtypes. This study highlights the discordance of subtype-specific proteins and therapeutic markers between SCLC primary tumors and LN metastases. Additionally, our findings have therapeutic and prognostic implications and warrant further clinical investigation.

The analysis of molecular classification of pulmonary neuroendocrine tumors and relationship between YAP1 and efficacy

A novel molecular classification for small cell lung cancer (SCLC) has been established utilizing the transcription factors achaete-scute homologue 1 (ASCL1), neurogenic differentiation factor 1 (NeuroD1), POU class 2 homeobox 3 (POU2F3), and yes-associated protein 1 (YAP1). This classification was predicated on the transcription factors. Conversely, there is a paucity of information regarding the distribution of these markers in other subtypes of pulmonary neuroendocrine tumors (PNET). Clinical and survival data for PNET patients were gathered from January 2008 to December 2020. Immunohistochemical analysis was employed to evaluate the expression. The relationship between YAP1 expression and outcomes in patients with pulmonary large cell neuroendocrine carcinoma (LCNEC) was examined. Data from low-grade PNET patients who had previously undergone immunotherapy were retrospectively gathered and analyzed. The ASCL1 positive rate was markedly elevated in SCLC (7.1% vs. 60%; P < 0.001) and LCNEC patients (7.1% vs. 38.5%; P = 0.034) compared to PC patients. The YAP1-positive rate was elevated in LCNEC compared to SCLC (43.6% vs. 20%, P = 0.028) and pulmonary carcinoid (PC) patients (43.6% vs. 21.4%; P = 0.021). The DLL3-positive rate in SCLC patients was greater than in SCLC and PC patients (37.1% vs. 23.1% vs. 0%; P = 0.028, P = 0.021). A significant level of tumor heterogeneity was noted, with SCLC and LCNEC patients exhibiting markedly higher heterogeneity than PC patients (65.7% vs. 56.3% vs. 21.4%; P = 0.005, P = 0.025). In patients with LCNEC, YAP1 positivity exhibited no correlation with PD-L1 expression (17.1% vs. 45.7%, P = 0.518). Tumor heterogeneity was also noted in transformed SCLC, with no significant differences in the expression levels of transcription factors between transformed and traditional SCLC. In 13 LCNEC patients with a history of ICI application, YAP1 exhibited no significant effect on PFS (P = 0.331) or OS (P = 0.17) in the subgroup analysis of LCNEC patients. Among the 14 patients with low-grade PNET who underwent immunotherapy, the disease control rate was 85.7%. Patients with high-grade PNET have high levels of expression of ASCL1 and DLL3, whereas patients with LCNEC have high levels of expression of YAP1. With regard to the transcription factor level, it was found that patients with SCLC and LCNEC had a much higher degree of tumor heterogeneity than those with PC. In patients with LCNEC who were receiving monotherapy of ICIs or chemotherapy in combination with ICIs, the expression of YAP1 did not appear to have any clear impact on the prognosis. This is due to the limited sample size of the study, which requires additional investigation. When compared to the expression of TFs in regular SCLC, the expression of TFs in converted SCLC is comparable.

Breathing new insights into the role of mutant p53 in lung cancer

The tumour suppressor gene p53 is one of the most frequently mutated genes in lung cancer and these defects are associated with poor prognosis, albeit some debate exists in the lung cancer field. Despite extensive research, the exact mechanisms by which mutant p53 proteins promote the development and sustained expansion of cancer remain unclear. This review will discuss the cellular responses controlled by p53 that contribute to tumour suppression, p53 mutant lung cancer mouse models and characterisation of p53 mutant lung cancer. Furthermore, we discuss potential approaches of targeting mutant p53 for the treatment of lung cancer.

KSR1 mediates small-cell lung carcinoma tumor initiation and cisplatin resistance

Small-cell lung cancer (SCLC) has a dismal five-year survival rate of less than 7%, with limited advances in first line treatment over the past four decades. Tumor-initiating cells (TICs) contribute to resistance and relapse, a major impediment to SCLC treatment. Here, we identify Kinase Suppressor of Ras 1 (KSR1), a molecular scaffold for the Raf/MEK/ERK signaling cascade, as a critical regulator of SCLC TIC formation and tumor initiation in vivo . We further show that KSR1 mediates cisplatin resistance in SCLC. While 50-70% of control cells show resistance after 6-week exposure to cisplatin, CRISPR/Cas9-mediated KSR1 knockout prevents resistance in >90% of SCLC cells in ASCL1, NeuroD1, and POU2F3 subtypes. KSR1 KO significantly enhances the ability of cisplatin to decrease SCLC TICs via in vitro extreme limiting dilution analysis (ELDA), indicating that KSR1 disruption enhances the cisplatin toxicity of cells responsible for therapeutic resistance and tumor initiation. The ability of KSR1 disruption to prevent cisplatin resistant in H82 tumor xenograft formation supports this conclusion. Previous studies indicate that ERK activation inhibits SCLC tumor growth and development. We observe a minimal effect of pharmacological ERK inhibition on cisplatin resistance and no impact on TIC formation via in vitro ELDA. However, mutational analysis of the KSR1 DEF domain, which mediates interaction with ERK, suggests that ERK interaction with KSR1 is essential for KSR1-driven cisplatin resistance. These findings reveal KSR1 as a key regulatory protein in SCLC biology and a potential therapeutic target across multiple SCLC subtypes.

Statement of Implication

Genetic manipulation of the molecular scaffold KSR1 in small-cell lung cancer cells reveals its contribution to cisplatin resistance and tumor initiation.

Polo-like Kinase 1 Inhibitors Demonstrate In Vitro and In Vivo Efficacy in Preclinical Models of Small Cell Lung Cancer

Objective: To investigate the preclinical efficacy and identify predictive biomarkers of polo-like kinase 1 (PLK1) inhibitors in small cell lung cancer (SCLC) models. Methods: We tested the cytotoxicity of selective PLK1 inhibitors (rigosertib, volasertib, and onvansertib) in a panel of SCLC cell lines. We confirmed the therapeutic efficacy of subcutaneous xenografts of representative cell lines and in four patient-derived xenograft models generated from patients with platinum-sensitive and platinum-resistant SCLC. We employed an integrated analysis of genomic and transcriptomic sequencing data to identify potential biomarkers of the activity and mechanisms of resistance in laboratory-derived resistance models. Results: Volasertib, rigosertib, and onvansertib showed strong in vitro cytotoxicity at nanomolar concentrations in human SCLC cell lines. Rigosertib, volasertib, and onvansertib showed equivalent efficacy to that of standard care agents (irinotecan and cisplatin) in vivo with significant growth inhibition superior to cisplatin in PDX models of platinum-sensitive and platinum-resistant SCLC. There was an association between YAP1 expression and disruptive or inactivation TP53 gene mutations, with greater efficacy of PLK1 inhibitors. Comparison of lab-derived onvansertib-resistant H526 cells to parental cells revealed differential gene expression with upregulation of NAP1L3, CYP7B1, AKAP7, and FOXG1 and downregulation of RPS4Y1, KDM5D, USP9Y, and EIF1AY highlighting the potential mechanisms of resistance in the clinical setting. Conclusions: We established the efficacy of PLK1 inhibitors in vitro and in vivo using PDX models of platinum-sensitive and resistant relapsed SCLC. An ongoing phase II trial is currently testing the efficacy of onvansertib in patients with SCLC (NCT05450965).

Nuclear factor I/B: Duality in action in cancer pathophysiology

The nuclear factor I (NFI) family of transcription factors plays a decisive role in organ development and maturation. Their deregulation has been linked with various diseases, most notably cancer. NFIB stands apart from the other NFI family members given its unique ability to drive both tumor suppressive and oncogenic programs. Thus, the ultimate impact of deregulated NFIB signaling is cancer-specific and strongly influenced by an intricate network of upstream regulators and downstream effectors. Deciphering the events that drive NFIB's paradoxical roles within these networks will enable us to not only understand how this critical transcription factor enacts its dual roles but also drive innovations to help us effectively target NFIB in different cancers. Here, we provide an in-depth review of NFIB. Starting with its defining role in the development of various organs, most notably the central nervous system, we highlight critical signaling pathways and the impact of deregulation on neoplastic transformation, contrasting it with the effect of silencing alone. We then provide examples of its dual roles in various cancers, identifying specific signaling networks associated with oncogenesis versus tumor suppression. We incorporate an example of a cancer type, osteosarcoma, wherein NFIB enacts its dual functions and explore which pathways influence each function. In this manner, we suggest plausible mechanisms for its role-switching from cancers sharing common triggering events in the setting of NFIB deregulation. We also review how NFIB enhances aggressiveness by driving metastasis, stemness, and chemoresistance. We conclude with a discussion on efficacious ways to target NFIB and pose some unanswered questions that may further help solidify our understanding of NFIB and facilitate clinical translation of NFIB targeting.

Concurrent RB1 and P53 pathway disruption predisposes to the development of a primitive neuronal component in high-grade gliomas depending on MYC-driven EBF3 transcription

The foremost feature of glioblastoma (GBM), the most frequent malignant brain tumours in adults, is a remarkable degree of intra- and inter-tumour heterogeneity reflecting the coexistence within the tumour bulk of different cell populations displaying distinctive genetic and transcriptomic profiles. GBM with primitive neuronal component (PNC), recently identified by DNA methylation-based classification as a peculiar GBM subtype (GBM-PNC), is a poorly recognized and aggressive GBM variant characterised by nodules containing cells with primitive neuronal differentiation along with conventional GBM areas. In addition, the presence of a PNC component has been also reported in IDH-mutant high-grade gliomas (HGGs), and to a lesser extent to other HGGs, suggesting that regardless from being IDH-mutant or IDH-wildtype, peculiar genetic and/or epigenetic events may contribute to the phenotypic skewing with the emergence of the PNC phenotype. However, a clear hypothesis on the mechanisms responsible for this phenotypic skewing is still lacking. We assumed that the biphasic nature of these entities represents a unique model to investigate the relationships between genetic alterations and their phenotypic manifestations. In this study we show that in HGGs with PNC features both components are highly enriched in genetic alterations directly causing cell cycle deregulation (RB inactivation or CDK4 amplification) and p53 pathway inactivation (TP53 mutations or MDM2/4 amplification). However, the PNC component displays further upregulation of transcriptional pathways associated with proliferative activity, including overexpression of MYC target genes. Notably, the PNC phenotype relies on the expression of EBF3, an early neurogenic transcription factor, which is directly controlled by MYC transcription factors in accessible chromatin sites. Overall our findings indicate that the concomitant presence of genetic alterations, impinging on both cell cycle and p53 pathway control, strongly predisposes GBM to develop a concomitant poorly differentiated primitive phenotype depending on MYC-driven EBF3 transcription in a subset of glioma stem-like progenitor cells.

Recent Advances in the Clinical Translation of Small-Cell Lung Cancer Therapeutics

Small-cell lung cancer (SCLC) is a recalcitrant form of cancer, representing 15% of lung cancer cases globally. SCLC is classified within the range of neuroendocrine pulmonary neoplasms, exhibiting shared morphologic, ultrastructural, immunohistochemical, and molecular genomic features. It is marked by rapid proliferation, a propensity for early metastasis, and an overall poor prognosis. The current conventional therapies involve platinum-etoposide-based chemotherapy in combination with immunotherapy. Nonetheless, the rapid emergence of therapeutic resistance continues to pose substantial difficulties. The genomic profiling of SCLC uncovers significant chromosomal rearrangements along with a considerable mutation burden, typically involving the functional inactivation of the tumor suppressor genes TP53 and RB1. Identifying biomarkers and evaluating new treatments is crucial for enhancing outcomes in patients with SCLC. Targeted therapies such as topoisomerase inhibitors, DLL3 inhibitors, HDAC inhibitors, PARP inhibitors, Chk1 inhibitors, etc., have introduced new therapeutic options for future applications. In this current review, we will attempt to outline the key molecular pathways that play a role in the development and progression of SCLC, together with a comprehensive overview of the most recent advancements in the development of novel targeted treatment strategies, as well as some ongoing clinical trials against SCLC, with the goal of improving patient outcomes.

Autophagic flux modulates tumor heterogeneity and lineage plasticity in SCLC

Introduction

Small cell lung cancer (SCLC) is characterized by significant heterogeneity and plasticity, contributing to its aggressive progression and therapy resistance. Autophagy, a conserved cellular process, is implicated in many cancers, but its role in SCLC remains unclear.

Methods

Using a genetically engineered mouse model (Rb1fl/fl ; Trp53fl/fl ; GFP-LC3-RFP-LC3△G), we tracked autophagic flux in vivo to investigate its effects on SCLC biology. Additional in vitro experiments were conducted to modulate autophagic flux in NE and non-NE SCLC cell lines.

Results

Tumor subpopulations with high autophagic flux displayed increased proliferation, enhanced metastatic potential, and neuroendocrine (NE) characteristics. Conversely, low-autophagic flux subpopulations exhibited immune-related signals and non-NE traits. In vitro, increasing autophagy induced NE features in non-NE cell lines, while autophagy inhibition in NE cell lines promoted non-NE characteristics.

Discussion

This study provides a novel model for investigating autophagy in vivo and underscores its critical role in driving SCLC heterogeneity and plasticity, offering potential therapeutic insights.

Pulmonary neuroendocrine neoplasms: the molecular landscape, therapeutic challenges, and diagnosis and management strategies

Lung neuroendocrine neoplasms are a group of diverse, heterogeneous tumours that range from well-differentiated, low-grade neuroendocrine tumours-such as typical and atypical carcinoids-to high-grade, poorly differentiated aggressive malignancies, such as large-cell neuroendocrine carcinoma (LCNEC) and small-cell lung cancer (SCLC). While the incidence of SCLC has decreased, the worldwide incidence of other pulmonary neuroendocrine neoplasms has been increasing over the past decades. In addition to the standard histopathological classification of lung neuroendocrine neoplasms, the introduction of molecular and sequencing techniques has led to new advances in understanding the biology of these diseases and might influence future classifications and staging that can subsequently improve management guidelines in the adjuvant or metastatic settings. Due to the rarity of neuroendocrine neoplasms, there is a paucity of prospective studies that focus on the lungs, especially in rare, well-differentiated carcinoids and LCNECs. In contrast with the success of targeted therapies in non-small-cell lung cancer (NSCLC), high-grade neuroendocrine carcinomas of the lung often only have a few specific targetable gene alterations. Optimal therapy for LCNECs is not well defined and treatment recommendations are based on extrapolating guidelines for the management of patients with SCLC and NSCLC. This Review explores the epidemiology, diagnosis, and staging of lung neuroendocrine neoplasms to date. In addition, we focus on the evolving molecular landscape and biomarkers, ranging from tumour phenotypes to functional imaging studies and novel molecular biomarkers. We outline the various clinical outcomes, challenges, the treatment landscape, ongoing clinical trials, and future directions.

Comparison of molecular subtype composition between independent sets of primary and brain metastatic small cell lung carcinoma and matched samples

INTRODUCTION

Recent advances in the subclassification of small cell lung carcinomas (SCLCs) may help to overcome the unmet need for targeted therapies and improve survival. However, limited information is available on how the expression of the subtype markers changes during tumour progression. Our study aimed to compare the expression of these markers in primary and brain metastatic SCLCs.

MATERIALS AND METHODS

Immunohistochemical analysis of the subtype markers was performed on 120 SCLCs (including 10 matched samples) and SCLC xenografts.

RESULTS

Compared to primary SCLCs, there was a significant increase in the proportion of mixed subtypes in brain metastases, with a rate of ASCL1high/NeuroD1high and ASCL1high/NeuroD1high/YAP1high subtypes increasing to 48 % and 18 %, respectively. The subtype of the paired samples matched in only one-third of the cases. Although we did not observe a significant change after chemotherapy, a continuous decrease in ASCL1 expression coupled with an increase in the NeuroD1 expression was detected in the xenografts in a long-term experiment.

DISCUSSION

Our results indicate that the expression of subtype markers frequently changes during disease progression, and subtype analysis of the primary SCLC may not provide accurate information about the characteristics of the recurrent or metastatic tumour. Therefore, repeated sampling and subtyping may be necessary for subtype-specific targeted therapy.

Lurbinectedin sensitizes PD-L1 blockade therapy by activating STING-IFN signaling in small-cell lung cancer

Lurbinectedin is an approved second-line treatment for small-cell lung cancer (SCLC). SCLC clinical trials combining lurbinectedin with PD-L1 blockade are currently ongoing. However, the immunomodulatory effects of lurbinectedin remain largely unknown. In this study, we demonstrate that lurbinectedin treatment activates the STING pathway, which increases interferon (IFN) signaling, pro-inflammatory chemokines, and major histocompatibility complex class I (MHC-I) in SCLC models. Lurbinectedin treatment augments the anti-tumor immune response of PD-L1 blockade with significant tumor regression in first-line and maintenance settings in SCLC mouse models. In vivo, lurbinectedin treatment increases CD8+ T cells and M1 macrophages and decreases immunosuppressive M2 macrophages. STING and CD8 depletion reverses the anti-tumor response. Interestingly, our study shows that lurbinectedin treatment upregulates MHC-I/II genes and CD8 in SCLC clinical samples. We provide mechanistic insights into the effect of lurbinectedin on STING-mediated multimodal immune activation and demonstrate that lurbinectedin treatment represents a promising therapeutic strategy to potentiate the efficacy of immunotherapy in SCLC.

Nomogram for predicting post-progression-free survival in patients with recurrent pancreatic ductal adenocarcinoma after radical surgery: a retrospective analysis

BACKGROUND

Radical resection is the only curative method for patients with pancreatic adenocarcinoma (PDAC). However, nearly 85% of PDAC patients suffer from local or distant recurrence within 5 years after curative resection. The progression of recurrent lesions accelerates the mortality rate in PDAC patients. However, the influence of clinicopathological factors on post-progression-free survival (PPFS), defined as the period from tumor recurrence to the timing of the progression of recurrent lesions, has rarely been discussed. The present study aimed to explore the independent prognostic factors for PPFS and construct a nomogram for PPFS prediction.

MATERIALS AND METHODS

The 200 recurrent PDAC patients were divided into training and validation groups by leave-one-out cross-validation. The patients' clinicopathological characteristics were compared through a chi-square test. Meanwhile, these factors were enrolled in the univariate and multivariate COX regression to find the independent prognostic factors of PPFS. Moreover, the Kaplan-Meier survival analysis based on the independent prognostic factors was performed. Finally, we constructed a nomogram model for PPFS prediction, followed by an effectiveness examination.

RESULTS

PDAC patients who received multi-agent chemotherapy after surgery showed a longer PPFS than the single-agent chemotherapy group. PDAC patients who received multi-agent chemotherapy after recurrence showed a similar PPFS compared to the single-agent chemotherapy group. Local recurrence with distant metastases, early recurrence, lympho-vascular invasion, higher T stage, and higher N stage predicted shorter PPFS in recurrent PDAC patients. Finally, a nomogram to indicate the progression of recurrent lesions was constructed.

CONCLUSION

Multi-agent chemotherapy is recommended for PDAC patients after surgery. Meanwhile, single-agent chemotherapy also deserves consideration after tumor recurrence. Moreover, the nomogram could be used in PPFS prediction.

A STAT3-STING-IFN axis controls the metastatic spread of small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor characterized by a high metastatic potential with an overall survival rate of ~5%. The transcription factor signal transducer and activator of transcription 3 (STAT3) is overexpressed by >50% of tumors, including SCLC, but its role in SCLC development and metastasis is unclear. Here, we show that, while STAT3 deletion restricts primary tumor growth, it paradoxically enhances metastatic spread by promoting immune evasion. This occurs because STAT3 is crucial for maintaining the immune sensor stimulator of interferon (IFN) genes (STING). Without STAT3, the cyclic adenosine monophosphate-guanosine monophosphate synthase-STING pathway is inactive, resulting in decreased type I IFN secretion and an IFN gene signature. Importantly, restoration of IFN signaling through re-expression of endogenous STING, enforced expression of IFN response factor 7 or administration of recombinant type I IFN re-established antitumor immunity, inhibiting metastatic SCLC in vivo. These data show the potential of augmenting the innate immune response to block metastatic SCLC.

Small cell lung cancer with liver metastases: from underlying mechanisms to treatment strategies

Small cell lung cancer (SCLC) represents an aggressive neuroendocrine (NE) tumor within the pulmonary region, characterized by very poor prognoses. Druggable targets for SCLC remain limited, thereby constraining treatment options available to patients. Immuno-chemotherapy has emerged as a pivotal therapeutic strategy for extensive-stage SCLC (ES-SCLC), yet it fails to confer significant efficacy in cases involving liver metastases (LMs) originating from SCLC. Therefore, our attention is directed towards the challenging subset of SCLC patients with LMs. Disease progression of LM-SCLC patients is affected by various factors in the tumor microenvironment (TME), including immune cells, blood vessels, inflammatory mediators, metabolites, and NE substances. Beyond standard immuno-chemotherapy, ongoing efforts to manage LMs in SCLC encompass anti-angiogenic therapy, radiotherapy, microwave ablation (MWA) / radiofrequency ablation (RFA), trans-arterial chemoembolization (TACE), and systemic therapies in conjunction with local interventions. Prospective experimental and clinical investigations into SCLC should prioritize precise and individualized approaches to enhance the prognosis across distinct patient cohorts.

Basal cell of origin resolves neuroendocrine-tuft lineage plasticity in cancer

Neuroendocrine and tuft cells are rare, chemosensory epithelial lineages defined by expression of ASCL1 and POU2F3 transcription factors, respectively1,2. Neuroendocrine cancers, including small cell lung cancer (SCLC), frequently display tuft-like subsets, a feature linked to poor patient outcomes3-13. The mechanisms driving neuroendocrine-tuft tumour heterogeneity, and the origins of tuft-like cancers are unknown. Using multiple genetically-engineered animal models of SCLC, we demonstrate that a basal cell of origin (but not the accepted neuroendocrine origin) generates neuroendocrine-tuft-like tumours that highly recapitulate human SCLC. Single-cell clonal analyses of basal-derived SCLC further uncovers unexpected transcriptional states and lineage trajectories underlying neuroendocrine-tuft plasticity. Uniquely in basal cells, introduction of genetic alterations enriched in human tuft-like SCLC, including high MYC, PTEN loss, and ASCL1 suppression, cooperate to promote tuft-like tumours. Transcriptomics of 944 human SCLCs reveal a basal-like subset and a tuft-ionocyte-like state that altogether demonstrate remarkable conservation between cancer states and normal basal cell injury response mechanisms14-18. Together, these data suggest that the basal cell is a plausible origin for SCLC and other neuroendocrine-tuft cancers that can explain neuroendocrine-tuft heterogeneity-offering new insights for targeting lineage plasticity.

Neuroendocrine Differentiation in Prostate Cancer Requires ASCL1

Most patients with prostate adenocarcinoma develop resistance to therapies targeting the androgen receptor (AR). Consequently, a portion of these patients develop AR-independent neuroendocrine (NE) prostate cancer (NEPC), a rapidly progressing cancer with limited therapies and poor survival outcomes. Current research to understand the progression to NEPC suggests a model of lineage plasticity whereby AR-dependent luminal-like tumors progress toward an AR-independent NEPC state. Genetic analysis of human NEPC identified frequent loss of RB1 and TP53, and the loss of both genes in experimental models mediates the transition to a NE lineage. Transcriptomics studies have shown that lineage transcription factors ASCL1 and NEUROD1 are present in NEPC. In this study, we modeled the progression of prostate adenocarcinoma to NEPC by establishing prostate organoids and subsequently generating subcutaneous allograft tumors from genetically engineered mouse models harboring Cre-induced loss of Rb1 and Trp53 with Myc overexpression (RPM). These tumors were heterogeneous and displayed adenocarcinoma, squamous, and NE features. ASCL1 and NEUROD1 were expressed within NE-defined regions, with ASCL1 being predominant. Genetic loss of Ascl1 in this model did not decrease tumor incidence, growth, or metastasis; however, there was a notable decrease in NE identity and an increase in basal-like identity. This study provides an in vivo model to study progression to NEPC and establishes the requirement for ASCL1 in driving NE differentiation in prostate cancer. Significance: Modeling lineage transitions in prostate cancer and testing dependencies of lineage transcription factors have therapeutic implications, given the emergence of treatment-resistant, aggressive forms of neuroendocrine prostate cancer. See related commentary by McQuillen and Brady, p. 3499.

The neuroendocrine transition in prostate cancer is dynamic and dependent on ASCL1

Lineage plasticity is a hallmark of cancer progression that impacts therapy outcomes, yet the mechanisms mediating this process remain unclear. Here, we introduce a versatile in vivo platform to interrogate neuroendocrine lineage transformation throughout prostate cancer progression. Transplanted mouse prostate organoids with human-relevant driver mutations (Rb1-/-; Trp53-/-; cMyc+ or Pten-/-; Trp53-/-; cMyc+) develop adenocarcinomas, but only those with Rb1 deletion advance to aggressive, ASCL1+ neuroendocrine prostate cancer (NEPC) resistant to androgen receptor signaling inhibitors. Notably, this transition requires an in vivo microenvironment not replicated by conventional organoid culture. Using multiplexed immunofluorescence and spatial transcriptomics, we reveal that ASCL1+ cells arise from KRT8+ luminal cells, progressing into transcriptionally heterogeneous ASCL1+;KRT8- NEPC. Ascl1 loss in established NEPC causes transient regression followed by recurrence, but its deletion before transplantation abrogates lineage plasticity, resulting in castration-sensitive adenocarcinomas. This dynamic model highlights the importance of therapy timing and offers a platform to identify additional lineage plasticity drivers.

Mechanisms governing lineage plasticity and metabolic reprogramming in cancer

Dynamic alterations in cellular phenotypes during cancer progression are attributed to a phenomenon known as 'lineage plasticity'. This process is associated with therapeutic resistance and involves concurrent shifts in metabolic states that facilitate adaptation to various stressors inherent in malignant growth. Certain metabolites also serve as synthetic reservoirs for chromatin modification, thus linking metabolic states with epigenetic regulation. There remains a critical need to understand the mechanisms that converge on lineage plasticity and metabolic reprogramming to prevent the emergence of lethal disease. This review attempts to offer an overview of our current understanding of the interplay between metabolic reprogramming and lineage plasticity in the context of cancer, highlighting the intersecting drivers of cancer hallmarks, with an emphasis on solid tumors.

FORMATION OF MALIGNANT, METASTATIC SMALL CELL LUNG CANCERS THROUGH OVERPRODUCTION OF cMYC PROTEIN IN TP53 AND RB1 DEPLETED PULMONARY NEUROENDOCRINE CELLS DERIVED FROM HUMAN EMBRYONIC STEM CELLS

We recently described our initial efforts to develop a model for small cell lung cancer (SCLC) derived from human embryonic stem cells (hESCs) that were differentiated to form pulmonary neuroendocrine cells (PNECs), a putative cell of origin for neuroendocrine-positive SCLC. Although reduced expression of the tumor suppressor genes TP53 and RB1 allowed the induced PNECs to form subcutaneous growths in immune-deficient mice, the tumors did not display the aggressive characteristics of SCLC seen in human patients. Here we report that the additional, doxycycline-regulated expression of a transgene encoding wild-type or mutant cMYC protein promotes rapid growth, invasion, and metastasis of these hESC-derived cells after injection into the renal capsule. Similar to others, we find that the addition of cMYC encourages the formation of the SCLC-N subtype, marked by high levels of NEUROD1 RNA. Using paired primary and metastatic samples for RNA sequencing, we observe that the subtype of SCLC does not change upon metastatic spread and that production of NEUROD1 is maintained. We also describe histological features of these malignant, SCLC-like tumors derived from hESCs and discuss potential uses of this model in efforts to control and better understand this recalcitrant neoplasm.