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PubMed2026

Efficacy of S-1 Monotherapy for Salivary Duct Carcinoma With MYC Amplification.

BACKGROUND/AIM: Salivary duct carcinoma (SDC) is a rare, highly aggressive subtype of salivary gland carcinoma, commonly characterized by overexpression of erb-b2 receptor tyrosine kinase 2 [ERBB2, commonly known as human epidermal growth factor receptor 2 (HER2)] and androgen receptor positivity. Anti-HER2 therapy, platinum-based chemotherapy, and androgen-deprivation therapy (ADT) are commonly provided as standard systemic treatments for advanced SDC; however, effective therapeutic options after failure of these treatments remain limited. The clinical efficacy of S-1 monotherapy in SDC and its predictive biomarkers are not well established. Herein, we present a case in which S-1 monotherapy showed efficacy in a case of SDC after resistance to anti-HER2 therapy, platinum-based chemotherapy, and ADT. CASE REPORT: The patient was a 70-year-old man diagnosed with HER2-positive and androgen receptor-positive SDC of the submandibular gland, who presented with multiple lung metastases. He initially received trastuzumab plus docetaxel as first-line therapy, followed by platinum-based chemotherapy and ADT, but experienced disease progression after each treatment. Comprehensive genomic profiling revealed amplifications of ERBB2 and MYC proto-oncogene bHLH transcription factor (MYC). S-1 monotherapy was started as a late-line therapy. Computed tomography scans 2 months later showed shrinkage of lung and liver metastases, with disease control maintained for more than 5 months. CONCLUSION: S-1 monotherapy may represent a treatment option for patients with advanced SDC refractory to anti-HER2 therapy, platinum-based chemotherapy, and ADT, particularly in cases harboring MYC amplification.

Humans↗

PubMed2025

Molecular features influencing clinical outcome of advanced HER2-positive gastric cancer receiving trastuzumab plus chemotherapy.

BACKGROUND: Less than half of the human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) patients respond to trastuzumab plus chemotherapy, and the outcomes are unsatisfactory. Understanding the underlying mechanisms remains crucial for identifying patients who are more likely to benefit from treatment. PATIENTS AND METHODS: We performed targeted DNA sequencing on paired pre-treatment and progressive tumour tissues from 22 HER2-positive advanced GC patients undergoing first-line treatment with trastuzumab and chemotherapy. Clinicopathological and genomic characteristics were assessed for the correlation with clinical outcomes. RESULTS: A performance status (PS) of 0-1 was associated with improved progression-free survival (PFS) and overall survival (OS) than a PS of 2. Poorly differentiated tumours exhibited shorter PFS than moderate or moderate-poor ones. Pre-treatment amplification of MYC or TOP2A gene was association with increased PFS, and suggested a potential benefit for OS. Patients with higher tumour mutation burden (TMB) experienced significantly worse PFS, while higher chromosome instability (CIN) appeared to be correlated with longer PFS. Compared to non-responders, responders had a higher CIN but similar TMB and intratumoural heterogeneity (ITH). PS and MYC amplification emerged as independent factors related to PFS according to multivariate survival analysis. Additionally, after treatment, TMB significantly increased in non-responders, while CIN significantly decreased in responders. CONCLUSIONS: Pre-treatment MYC amplification and PS were independently associated with clinical outcomes in HER2-positive advanced GC patients treated with first-line trastuzumab plus chemotherapy. Dynamic post-treatment changes in TMB and CIS provide valuable insights into the relationship between therapeutic response and distinct evolutionary trajectories.

Humans↗

PubMed2025

Targeting the MYC oncogene with a selective bi-steric mTORC1 inhibitor elicits tumor regression in MYC-driven cancers.

The MYC oncogene is causally involved in the pathogenesis of most human cancers. The mTORC1 complex regulates MYC translation through 4EBP1 and S6K. However, agents that selectively target mTORC1 (without affecting mTORC2) have so far failed to reactivate 4EBP1 and, thus, cannot effectively suppress MYC in vivo. In contrast, nonselective inhibitors that block both mTOR complexes can activate 4EBP1, but often lack tolerability and induce immunosuppression. Here, we introduce bi-steric mTORC1-selective inhibitors, including the clinical candidate RMC-5552, which potently reactivate 4EBP1 and decrease MYC protein expression levels. Consequently, suppression of MYC signaling occurs, resulting in tumor growth inhibition through both direct effects on tumor cells and immune activation. RMC-5552 exhibits anti-tumor activity in human patient-derived xenografts models harboring genomic MYC amplifications and reduces MYC protein levels in vivo. Furthermore, bi-steric mTORC1-selective inhibitors enhance the efficacy of immune checkpoint blockade, leading to tumor regression.

Mechanistic Target of Rapamycin Complex 1↗

PubMed2026

[Aggressive B-cell lymphomas with MYC gene cluster amplification: a clinicopathological analysis of eight cases].

Objective: To investigate the clinicopathological characteristics, molecular genetics, treatments and prognosis of aggressive B-cell lymphomas (ABCL) with MYC gene cluster amplification. Methods: Eight cases of ABCL with MYC gene cluster amplification were collected, including 6 cases from the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and 2 consultation cases from outside hospitals. The histomorphology, immunohistochemical profiles, and molecular genetic characteristics were analyzed. Clinical follow-up and literature review were also conducted. Results: Among the eight patients, six were male and two were female, with an age 71.5 (61.7, 74.2) years. All six in-house patients presented with abdominal pain at onset, without B symptoms. Most cases were classified as Ann Arbor stage Ⅲ-Ⅳ. Extranodal involvement occurred in 5 of the 6 in-house cases, primarily affecting the gastrointestinal tract (4/5). All initial bone marrow biopsies showed no evidence of lymphoma. One patient had a history of immunosuppression following renal transplantation. Two cases exhibited diffuse large B-cell lymphoma (DLBCL) morphology. The other six showed high-grade features, while three of them showed Burkitt lymphoma-like morphology. Except for one case of blastoid variant mantle cell lymphoma, the remaining six cases (6/7) displayed a germinal center B-cell phenotype. None of the in-house cases harbored bcl-2 or bcl-6 rearrangements as shown by fluorescence in situ hybridization. 11q alterations were identified in all but one consultation case, including gain/loss type in five cases and 11q gain in two. 11q telomere loss of heterozygosity by chromosomal microarray analysis was not detected in one of the two cases with 11q gain that was subject to the test. The duration of follow-up ranged from 5.9 to 55.5 months, with 5 patients alive at the end of the study. Conclusions: ABCL with MYC gene cluster amplification often presents high-grade morphology and gastrointestinal involvement, which strongly suggests the alteration of 11q. It seems to have a favorable prognosis.

Humans↗

PubMed2025

MYC and p53 Alterations Cooperate through VEGF Signaling to Repress Cytotoxic T-cell and Immunotherapy Responses in Prostate Cancer.

UNLABELLED: Patients with castration-resistant prostate cancer (CRPC) are generally unresponsive to tumor-targeted treatments and immunotherapies. Genetic alterations acquired during the evolution of CRPC may affect antitumor immunity and immunotherapy responses, which could inform personalized therapeutic strategies. Using our innovative electroporation-based mouse models, we generated distinct genetic subtypes of CRPC found in patients and uncovered unique immune microenvironments. Specifically, mouse and human prostate tumors with MYC amplification and p53 disruption had weak cytotoxic lymphocyte infiltration and an overall dismal prognosis. MYC and p53 cooperated to induce tumor-intrinsic secretion of VEGF, which signaled through VEGFR2 expressed on CD8+ T cells to directly inhibit T-cell migration and effector functions. Targeting VEGF-VEGFR2 signaling in vivo remodeled the immunosuppressive prostate tumor microenvironment, leading to CD8+ T-cell-mediated primary tumor and metastasis growth suppression and significantly increased overall survival in MYC- and p53-altered CRPC. VEGFR2 blockade also led to the induction of PD-L1 in tumors and produced antitumor efficacy in combination with PD-L1 immune checkpoint blockade in multiple preclinical CRPC mouse models. Thus, these results identify a genetic mechanism of immunosuppression through VEGF signaling in prostate cancer that can be targeted to reactivate immune and immunotherapy responses in an aggressive subtype of CRPC. SIGNIFICANCE: VEGFR2 blockade inhibits VEGF-mediated T-cell suppression and potentiates the effects of PD-L1 immune checkpoint blockade to treat castration-resistant prostate cancer driven by MYC and p53 alterations.

Male↗

PubMed2026

MondoA mediates transcriptional coordination between the MYC network and the integrated stress response in pancreatic cancer.

MYC amplification contributes to poor survival and outcome in pancreatic ductal adenocarcinoma (PDAC). Here we show that in PDAC cell lines with amplified MYC, MondoA is required for viability, facilitating proliferation while suppressing apoptosis in vitro and in vivo. Transcriptional and genomic profiling demonstrates that loss of MondoA leads to altered expression of direct MondoA targets as well as MYC target genes and is accompanied by shifts in genomic occupancy of MYC, MNT, and the MondoA paralog ChREBP. This altered genomic binding by MYC network members is associated with transcriptional perturbation of multiple metabolic and stress pathways, as well as global changes in N6-methyladenosine modification (m6A) of messenger RNA (mRNA). MondoA inhibition disrupts coordination between MYC network members and the Integrated Stress Response (ISR), resulting in decreased translation of ATF4 mRNA, discordant gene regulation of shared targets of MYC and ATF4 and, ultimately, apoptosis. Reestablishing ATF4 protein expression rescues the diminished viability due to loss of MondoA expression or activity, providing direct evidence of a link between deregulated MYC and the transcriptional machinery of the ISR. Last, we find that small-molecule inhibition of MondoA is lethal in a subset of PDAC cell lines, including patient-derived organoids, suggesting that the ability to target MYC via chemical inhibition of MondoA transcriptional activity may have broad efficacy.

Humans↗

PubMed2025

MondoA mediates transcriptional coordination between the MYC network and the integrated stress response in pancreatic ductal adenocarcinoma.

MYC amplification contributes to poor survival and outcome in pancreatic ductal adenocarcinoma (PDAC). Here we show that in PDAC cell lines with amplified MYC, MondoA is required for viability, facilitating proliferation while suppressing apoptosis in vitro and in vivo. Transcriptional and genomic profiling demonstrates that loss of MondoA leads to altered expression of direct MondoA targets as well as MYC target genes and is accompanied by shifts in genomic occupancy of MYC, MNT, and the MondoA paralog ChREBP. This altered genomic binding by MYC network members is associated with transcriptional perturbation of multiple metabolic and stress pathways, as well as global changes in N6-methyladenosine modification (m6A) of mRNA. MondoA inhibition disrupts coordination between MYC network members and the Integrated Stress Response (ISR), resulting in decreased translation of ATF4 mRNA, discordant gene regulation of shared targets of MYC and ATF4 and, ultimately, apoptosis. Re-establishing ATF4 protein expression rescues the diminished viability due to loss of MondoA expression or activity, providing direct evidence of a link between deregulated MYC and the transcriptional machinery of the ISR. Lastly, we find that small-molecule inhibition of MondoA is lethal in a subset of PDAC cell lines, including patient-derived organoids, suggesting that the ability to target MYC via chemical inhibition of MondoA transcriptional activity may have broad efficacy.

Cell Biology↗

PubMed2026

Pleomorphic Liposarcoma: Comprehensive Genomic Analysis of 39 Cases With Comparison to Other Genomically Complex Sarcomas.

Pleomorphic liposarcoma (PLPS) is an aggressive high-grade sarcoma that often shows diverse morphological features and can mimic high-grade undifferentiated pleomorphic sarcoma (UPS)/spindle cell sarcoma or myxofibrosarcoma (MFS), especially when pleomorphic lipoblasts are sparse. The molecular profile of PLPS is distinct from well differentiated/dedifferentiated liposarcoma and myxoid liposarcoma. In this study, we investigate 39 cases of PLPS by comprehensive genomic profiling, occurring in 32 patients with available molecular data. Cases were reviewed and morphologic parameters-lipoblastic component, UPS-like, and MFS-like areas were estimated. The genomic findings were collected and compared to UPS and MFS groups studied using the same platform. The cohort included 15 females and 17 males, with a median age of 56.5 (range, 34-78). The lower extremity (n = 17) was the most common site involved, followed by upper extremity (n = 5) and pelvis (n = 5). UPS-like and MFS-like patterns were the most common morphologic variants, ranging from 15% to 95% and 20% to 90%, respectively. TP53 (87%) and RB1 (51%) mutations and copy number alterations were the most common alterations seen, followed by ATRX (36%). Compared to UPS and MFS, TP53 and RB1 gene alterations were significantly more common in PLPS. Conversely, CDKN2A/B deletions were infrequent in PLPS. Survival analysis showed that MYC amplification was associated with significantly shorter overall survival in PLPS. Among histologic variants, CYSLTR2 alterations were found to be highest in cases with predominantly pleomorphic lipoblasts; additionally, strong correlations were found between gene alteration frequencies of MFS and MFS-like PLPS, and between UPS and UPS-like PLPS. RB1 allele-specific copy number analysis showed loss of heterozygosity in 82% of cases. Our cohort of PLPS showed a complex molecular landscape with distinct genetic alterations, histologic correlations, and clinical outcomes, highlighting its unique position among genomically complex sarcomas and providing insights that may inform future diagnostic and therapeutic approaches.

Humans↗

PubMed2026

Clinical outcomes and genomic features of uncommon EGFR exon 19 deletion subtypes in osimertinib-treated non-small cell lung cancer.

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 19 deletion subtypes may be associated with differential survival outcomes following EGFR-tyrosine kinase inhibitor treatment. However, evidence remains scarce, particularly regarding osimertinib, and the underlying biological mechanisms are poorly understood. We aimed to compare survival outcomes among EGFR exon 19 deletion subtypes in patients with non-small cell lung cancer (NSCLC) treated with osimertinib. METHODS: In this multicenter retrospective study, patients with NSCLC were stratified according to exon 19 deletion subtypes. Whole-exome sequencing data from the American Association for Cancer Research Genomics Evidence Neoplasia Information Exchange registry and Memorial Sloan Kettering Clinicogenomic Harmonized Oncologic Real-World Dataset were analyzed to investigate co-occurring genomic alterations. RESULTS: Overall, 111 patients with advanced EGFR exon 19 deletion-positive NSCLC were analyzed and 86.5% received osimertinib as first-line therapy. Patients with non-E746_A750del (n = 25) had shorter progression-free survival (PFS) than those with E746_A750del (n = 86) (median: 14.3 vs. 20.6 months; p < 0.05). Among non-E746_A750del subtypes, L747_A750delinsP (n = 4) had a particularly poor prognosis, with significantly worse survival than those with E746_A750del (median PFS: 3.5 vs. 20.6 months; p < 0.001, and median overall survival: 11.8 vs. 48.5 months; p < 0.001). In public database analyses, non-E746_A750del had a higher rate of RBM10 co-mutations, whereas L747_A750delinsP was characterized by frequent CDKN2A/B homozygous deletions and MYC amplifications. CONCLUSIONS: Non-E746_A750del was associated with poorer outcomes, with L747_A750delinsP potentially being a high-risk subtype. Differences in co-occurring genomic alterations may contribute to the prognostic heterogeneity among exon 19 deletion subtypes.

Humans↗

PubMed2026

Intraductal Papillary Squamous Neoplasm (IPSN) of the Pancreas: Histological and Molecular Characterization of a Novel and Distinct Intraductal Cancer Precursor.

We report 6 intraductal papillary squamous neoplasms (IPSNs) of the pancreas, a rare but distinctive tumor whose biological features remain largely unknown. Five cases were investigated using an integrated approach combining histomorphological evaluation, immunohistochemistry, and multiregional molecular profiling through whole-exome DNA sequencing and whole-transcriptome RNA sequencing. Only targeted DNA sequencing was available on a sixth recently diagnosed case. Histologically, the intraductal lesions were characterized by large, confluent papillae with fibrovascular cores lined by multilayered epithelial cells with diffuse squamous differentiation. All cases harbored a concomitant invasive carcinoma. The associated invasive carcinomas consistently included a pancreatic tubular/ductal adenocarcinoma; in 5 cases, a poorly differentiated squamous cell carcinoma was also present, the proportion/features of which met the diagnostic criteria of adenosquamous carcinoma in 2 of them. Genomic analyses revealed that IPSNs and their matched invasive carcinomas shared the majority of somatic alterations, supporting a shared clonal origin for the 2 components. Activating KRAS mutations and biallelic inactivation of CDKN2A were detected in all cases. Recurrent mutations involved members of the SWI/SNF chromatin-remodeling complex and KMT2D. Additionally, FGFR1 and MYC amplifications were identified in 2 distinct cases (1 case each). Molecular alterations restricted to the invasive component involved mediators of the transforming growth factor-β signaling pathway. Transcriptomic profiling demonstrated a basal-like expression pattern in all IPSNs and squamous cell carcinomas, although in 2 cases, the matched pancreatic tubular/ductal adenocarcinoma shifted toward a classical transcriptomic subtype. In conclusion, through integrated histological assessment and multiregional molecular sequencing, we demonstrate that IPSN represents a bona fide precursor of invasive pancreatic cancer, a new addition to the intraductal neoplasms category. This study challenges the current paradigm that pancreatic squamous epithelium plays no role in the initiation of pancreatic carcinogenesis, providing the first evidence of its involvement in early tumorigenic processes and yielding immediate implications for pancreatic tumor classification and biological understanding.

Humans↗

PubMed2026

Marked response to dabrafenib plus trametinib in a patient with BRAF V600E-mutant pancreatic hepatoid carcinoma: a case report and systematic analysis of 57 cases.

BACKGROUND: Pancreatic hepatoid carcinoma (PHC) is an extremely rare pancreatic malignancy characterized pathologically by hepatocellular-like differentiation. Some patients may present with elevated serum alpha-fetoprotein (AFP). Owing to the limited number of reported cases, the clinical features, molecular characteristics, and systemic treatment strategies for PHC remain poorly defined. BRAF V600E is an actionable alteration with established therapeutic value in several solid tumors; however, its clinical significance in PHC remains unclear. CASE PRESENTATION: We report the case of a 64-year-old man with advanced PHC who presented with painless jaundice, dark urine, and recent weight loss. Laboratory tests showed marked cholestatic liver injury and significantly elevated AFP. Imaging revealed a pancreatic head-neck mass with portal vein tumor thrombus and regional lymph node metastases, corresponding to cT4N1M1, stage IV disease. Percutaneous transhepatic biliary drainage was first performed to relieve obstructive jaundice. Biopsy of the pancreatic lesion showed poorly differentiated carcinoma. Based on hepatoid morphology, immunophenotype, elevated serum AFP, imaging findings, and exclusion of primary hepatocellular carcinoma, the patient was diagnosed with PHC. Comprehensive genomic profiling identified a BRAF V600E mutation with a variant allele frequency of 31.89%, together with MDM2 and MYC amplification. The molecular profile was characterized by microsatellite stability, low tumor mutational burden, MGMT promoter methylation, and low PD-L1 expression. After two cycles of pembrolizumab-based first-line therapy combined with paclitaxel, S-1, and lenvatinib, AFP continued to increase and imaging showed rapid tumor enlargement, consistent with immune checkpoint inhibitor-related hyperprogressive disease. The treatment was then switched to dabrafenib plus trametinib. AFP declined rapidly and returned to the normal range within approximately two months. Imaging showed marked regression of the pancreatic primary lesion, disappearance of the portal vein tumor thrombus and metastatic lymph nodes, and conversion of peripheral blood minimal residual disease to negative. The best response was partial response. After approximately six months of targeted therapy, occult disease progression emerged. Subsequent addition of cetuximab, replacement of the MEK inhibitor, and dose escalation of targeted therapy did not restore sustained systemic disease control, although local disease remained manageable with subsequent treatment adjustments. Proton radiotherapy was then delivered to the residual pancreatic lesion, followed by CyberKnife radiotherapy for a newly detected 2.3-cm metastasis in the caudate lobe of the liver. As of April 2026, the patient's AFP level remained close to normal at 14 ng/mL, local lesions were well controlled, peripheral blood minimal residual disease had turned positive, and the patient remained in a stable tumor-bearing state. SYSTEMATIC ANALYSIS: We further summarized 57 previously reported cases of PHC. The median age was 54 years, and 66.7% of patients were male. Tumors occurred at different pancreatic sites, including the pancreatic head in 21 cases, body in 8 cases, tail in 13 cases, and multifocal lesions in 15 cases. More than half of the patients had metastatic disease at initial diagnosis. The immunophenotype of PHC was highly heterogeneous. Regarding treatment, 47 patients underwent surgery, 20 received chemotherapy, and 6 received targeted therapy. The 1-year and 3-year overall survival rates were 70.7% and 43.1%, respectively, indicating an overall poor prognosis. CONCLUSION: This case suggests that BRAF V600E may represent a clinically actionable driver alteration in PHC. Dabrafenib plus trametinib induced a rapid and deep response in this patient with advanced BRAF V600E-mutant PHC. Microsatellite stability, low tumor mutational burden, low PD-L1 expression, and MDM2 amplification may be associated with limited benefit from immunotherapy and a risk of hyperprogression. After resistance to targeted therapy, local radiotherapy may serve as an important strategy for controlling oligoresidual and oligometastatic lesions. Together with the literature review, this case supports early comprehensive molecular profiling and individualized multidisciplinary management for advanced PHC.

BRAF V600E↗

PubMed2026

The Genomic Landscape of MYC-, MYCL-, and MYCN-Amplified Solid Tumors.

PURPOSE: MYC, MYCN, and MYCL amplifications are recurrent oncogenic events across solid tumors. Currently, no standardized selection biomarker is available to identify patients with MYC-dependent tumors. EXPERIMENTAL DESIGN: We analyzed copy-number alterations of MYC family genes and their features in more than 68,000 tumor-normal paired samples from pediatric and adult patients sequenced with MSK-IMPACT (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) and annotated with FACETS (Fraction and Allele-Specific Copy Number Estimates from Tumor Sequencing). The relationship between amplification features and MYC mRNA expression levels were evaluated in more than 10,000 samples from The Cancer Genome Atlas (TCGA). RESULTS: Across MSK Cancer Center samples, MYC amplifications were most common, found in 2,949 samples compared with 310 in MYCL and 217 in MYCN. Although MYCN and MYCL amplifications were predominantly focal (<10 Mb, 79% and 93%, respectively), MYC amplifications were frequently broader (>10 Mb, 62%). Although most tumor types showed similar features between broad and focal amplifications of MYC, in select cancer types, we identified differing co-occurrence and mutual exclusivity patterns with other disease-specific drivers. Furthermore, although MYC-amplified TCGA samples showed higher mRNA expression than wild-type ones, the focality of MYC amplification was seen to have limited influence on expression levels. CONCLUSIONS: Our results suggest that MYC dependency likely depends on many factors, including, but not limited to, total copy number of the detected amplification, lineage-specific factors, concomitant presence or absence of additional oncogenic alterations, and in some cases amplification focality.

Humans↗

PubMed2026

Genomic and transcriptomic features of relapsed small cell lung cancer.

BACKGROUND: Relapsed small cell lung cancer is characterized by treatment resistance and poor outcomes. Genomic and transcriptomic alterations in relapsed SCLC have not been characterized well. We comprehensively profiled relapsed SCLC samples along with patient-matched treatment-naive samples, when available, using whole-exome (WES), whole-genome (WGS), and RNA-sequencing (RNA-seq) to describe the molecular landscape of relapsed SCLC. Our goal is to identify potential novel pathways for additional functional validation and eventually novel therapeutic options. METHODS: We analyzed 54 relapsed and 27 treatment-naive SCLC samples using WES (with 26 patient-matched paired samples). A subset of the samples was also analyzed by WGS (n=28) and RNA-seq (n=31). Differences in mutational signatures, gene expression, structural variants, splicing, and neoantigen profiles at diagnosis and relapse were investigated. RESULTS: Relapsed SCLC samples demonstrated mutation signatures characteristic of platinum and APOBEC mutagenesis. Furthermore, these samples were characterized by MYC, MYCL and MYCN amplifications. Both treatment-naive and relapsed SCLC samples showed high prevalence of mutation-associated neoantigens (median= 86 in treatment-naive and 90 in relapsed SCLC; p=0.8) and TP53 was the most frequently altered gene to result in a neoantigen (48% of analyzed samples). Potential mechanisms of immune evasion, including amplification of CD24, overexpression of IDO1, increased M2 macrophage presence, and upregulation of HLA-E were also observed in relapse samples. Differences in alternative splicing patterns were observed between treatment-naive and relapsed small cell samples. Retained intron events were significantly enriched in treatment-naive samples and affected genes involved in DNA repair, metabolism, and WNT and MYC pathways. CONCLUSIONS: This study highlights the genomic and transcriptomic features of relapsed SCLC. These samples were characterized by genomic instability, WNT and MYC dysregulation, and splicing aberrations. Additional studies targeting the splicing machinery, WNT signaling, and immune evasion pathways could identify novel therapeutic vulnerabilities in SCLC.

Journal Article↗

PubMed2026

Identification and characterization of ectopic chromosomal amplifications in acute myeloid leukemia cell limes using high-throughput chromosome conformation capture screening.

Despite advanced molecular diagnostics, improving outcomes for refractory acute myeloid leukemia (AML) remains challenging. Although many cancer-related genes are identified, their molecular mechanisms are not fully elucidated. Amplification is a mechanism of cancer-associated gene activation, and ectopic gene amplification may have particularly high pathological significance. However, research on ectopically amplified cancer-associated genes in leukemia remains limited. Here, we evaluated the usefulness of high-throughput chromosomal conformation capture (Hi-C) as a screening method for ectopic gene amplification and assessed whether ectopic amplification of cancer-associated genes may represent a general phenomenon in AML. We screened the U-937 and NB-4 cell lines using in situ Hi-C. Regions appearing as "high-intensity bands" in Hi-C contact maps were identified and validated using fluorescence in situ hybridization (FISH). Additionally, copy number variation analysis was performed using whole-genome sequencing (WGS) to extract cancer-associated genes with ectopic amplification. In the U-937, three genomic regions showing "high-intensity bands" were identified and confirmed as ectopic amplifications-including PDCD1LG2 (PD-L2), CD274 (PD-L1), and JAK2; that is, four copies were detected by WGS, and amplification signals were observed by FISH. In the NB-4, four such regions were detected, including MYC and KRAS, with expression level of 498 transcripts per million (TPM) and 34 TPM, respectively. Copy number variation analysis further identified multiple cancer-associated genes with ectopic amplification. Overall, these findings demonstrate the presence of ectopic amplification of cancer-associated genes in AML cell lines and support the usefulness of Hi-C as a screening method for detecting such genomic alterations.

Acute myeloid leukemia↗

PubMed2025

Extrachromosomal DNA-Driven Oncogene Dosage Heterogeneity Promotes Rapid Adaptation to Therapy in MYCN-Amplified Cancers.

UNLABELLED: Extrachromosomal DNA (ecDNA) amplification enhances intercellular oncogene dosage variability and accelerates tumor evolution by violating foundational principles of genetic inheritance through its asymmetric mitotic segregation. Spotlighting high-risk neuroblastoma, we demonstrate how ecDNA amplification undermines the clinical efficacy of current therapies in cancers with extrachromosomal MYCN amplification. Integrating theoretical models of oncogene copy number-dependent fitness with single-cell ecDNA quantification and phenotype analyses, we reveal that ecDNA copy-number heterogeneity drives phenotypic diversity and determines treatment sensitivity through mechanisms unattainable by chromosomal oncogene amplification. We demonstrate that ecDNA copy number directly influences cell fate decisions in cancer cell lines, patient-derived xenografts, and primary neuroblastomas, illustrating how extrachromosomal oncogene dosage-driven phenotypic diversity offers a strong evolutionary advantage under therapeutic pressure. Furthermore, we identify senescent cells with reduced ecDNA copy numbers as a source of treatment resistance in neuroblastomas and outline a strategy for their targeted elimination to improve the treatment of MYCN-amplified cancers. SIGNIFICANCE: ecDNA-driven tumor genome evolution provides a major challenge to curative cancer therapies. We demonstrate that ecDNA copy-number dynamics drives treatment resistance by promoting oncogene dosage-dependent phenotypic heterogeneity in MYCN-amplified cancers. Exploiting phenotype-specific vulnerabilities of ecDNA cells, therefore, presents a powerful strategy to overcome treatment resistance. See related commentary by Korsah, p. 1979.

Humans↗

PubMed2025

In Vivo CRISPR Activation Screening Reveals Chromosome 1q Genes VPS72, GBA1, and MRPL9 Drive Hepatocellular Carcinoma.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) frequently undergoes regional chromosomal amplification, resulting in elevated gene expression levels. We aimed to elucidate the role of these poorly understood genetic changes by using CRISPR activation (CRISPRa) screening in mouse livers to identify which genes within these amplified loci are cancer driver genes. METHODS: We used data from The Cancer Genome Atlas to identify that frequently copy number-amplified and up-regulated genes all reside on human chromosomes 1q and 8q. We generated CRISPRa screening transposons that contain oncogenic Myc to drive tumor formation. We conducted CRISPRa screens in vivo in the liver to identify tumor driver genes. We extensively validated the findings in separate mice and performed RNA sequencing analysis to explore mechanisms driving tumorigenesis. RESULTS: We targeted genes that frequently undergo amplification in human HCC using an in vivo CRISPRa screening system in mice, which induced extensive liver tumorigenesis. Human chromosome 1q genes Zbtb7b, Vps72, Gba1, and Mrpl9 emerged as drivers of liver tumorigenesis. In human HCC there is a trend in correlation between levels of MRPL9, VPS72, or GBA1 and poor survival. In validation assays, activation of Vps72, Gba1, or Mrpl9 resulted in extensive liver tumorigenesis and decreased survival in mice. RNA sequencing revealed different mechanisms driving HCC, with Mrpl9 activation altering genes functionally related to mitochondrial function, Vps72 levels altering phospholipid metabolism, and Gba1 activation enhancing endosomal-lysosomal activity, all leading to promotion of cellular proliferation. Analysis of human tumor tissues with high levels of MRPL9, VPS72, or GBA1 revealed congruent results, indicating conserved mechanisms driving HCC. CONCLUSIONS: This study reveals chromosome 1q genes Vps72, Gba1, and Mrpl9 as drivers of HCC. Future efforts to prevent or treat HCC can focus on these new driver genes.

Animals↗

PubMed2026

Driver genomic lesions in MDM2, CDK4, and JUN co-opt targetable super-enhancer networks to impose liposarcomagenic core regulatory circuitry.

INTRODUCTION: Amplification of chromosome 12q13-15 spanning MDM2 and CDK4 genes serves as a molecular diagnostic hallmark of dedifferentiated liposarcoma (DDLPS), an aggressive soft-tissue sarcoma. Epigenetic activation of master transcription factors (RUNX proteins, FOSL2, and MYC) establishes a self-reinforcing oncogenic transcriptional circuitry in DDLPS. Nevertheless, the collaborative interplay between genomic alterations and epigenetic dysregulation in defining DDLPS cell identity remains elusive. OBJECTIVES: This work aimed to elucidate the primary genetic drivers and mechanistic basis of DDLPS-specific core transcriptional regulatory circuitry. METHODS: We performed integrative chromatin profiling analysis of DDLPS clinical specimens and cell lines to map cis-regulatory landscapes. Cistromes of MDM2, JUN, and E2F1 were delineated through chromatin immunoprecipitation sequencing in two DDLPS models. Essential driver functions and transcriptional regulatory effects of key regulators were assessed via various genetic manipulation approaches. Synergistic interactions between BET-targeting agents and MDM2/p53 or CDK4 inhibitors were quantified by cell viability assays. In vivo xenograft assays evaluated the oncogenic potential of key regulators and the therapeutic efficacy of novel strategies. RESULTS: Co-amplification of MDM2, CDK4, and JUN during sarcomagenesis converges with BET protein-dependent chromatin remodeling to fuel feed-forward transcriptional circuits among master transcription factors. Mechanistically, excessively expressed MDM2 stabilizes the core regulatory circuitry by forming chromatin-bound complexes with JUN/FOSL2 at cis-regulatory elements, especially super-enhancers across DDLPS genome. Concurrently, CDK4 maintains expression of E2F1 which further fosters transcriptional output of master transcription factors in DDLPS cells. Leveraging DDLPS-selective overexpression of MDM2 and its E3 ligase activity, targeted degradation of BET proteins by MDM2-recruiting proteolysis targeting chimera selectively disrupted the core regulatory circuitry, suppressing DDLPS growth and exhibiting strong synergy with CDK4 inhibitor. CONCLUSION: DDLPS-associated genomic lesions collaborate with BET-dependent chromatin regulation to establish disease-sustaining transcriptional circuitry. Our findings also provide a mechanistic rationale for harnessing MDM2's E3 ligase activity to therapeutically degrade oncoproteins in MDM2-amplified malignancies.

Core transcriptional regulatory circuitry↗

PubMed2025

Enhancer activation from transposable elements in extrachromosomal DNA.

Extrachromosomal DNA (ecDNA) drives oncogene amplification and intratumoral heterogeneity in aggressive cancers. While transposable element (TE) reactivation is common in cancer, its role on ecDNA remains unexplored. Here, we map the 3D architecture of MYC-amplified ecDNA in colorectal cancer cells and identify 68 ecDNA-interacting elements (EIEs)-genomic loci enriched for TEs that are frequently integrated onto ecDNA. We focus on an L1M4a1#LINE/L1 fragment co-amplified with MYC, which functions only in the ecDNA amplified context. Using CRISPR-CATCH, CRISPR interference, and reporter assays, we confirm its presence on ecDNA, enhancer activity, and essentiality for cancer cell fitness. These findings reveal that repetitive elements can be reactivated and co-opted as functional rather than inactive sequences on ecDNA, potentially driving oncogene expression and tumor evolution. Our study uncovers a mechanism by which ecDNA harnesses repetitive elements to shape cancer phenotypes, with implications for diagnosis and therapy.

Journal Article↗