Colorectal cancer (CRC) exhibits substantial molecular heterogeneity, yet detailed single-cell transcriptomic data from Japanese patients remain limited. Here, we performed single-cell RNA sequencing (scRNA-seq) on tumor tissues and adjacent normal tissues from four Japanese CRC patients to characterize malignant cell populations. We identified a common cancer-associated cell cluster observed across all four cases, characterized by high expression of the long noncoding RNA KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1). Further analysis revealed a marked decrease in Ras Association Domain Family Member 6 (RASSF6) expression within this cluster, despite clinical datasets reporting that elevated RASSF6 expression correlates with poor overall survival in Western cohorts. Reanalysis of publicly available bulk RNA-seq data from independent East Asian cohorts confirmed that RASSF6 expression was consistently reduced in tumor tissues compared with adjacent normal colon tissues, while KCNQ1OT1 expression showed no apparent differences across cohorts. Collectively, our single-cell analysis delineates a recurrent cancer-associated transcriptional state observed within this cohort and highlights distinct gene expression features that may be underappreciated by bulk or population-averaged analyses, underscoring the value of single-cell profiling for refining molecular interpretations of CRC.

Mitochondria are not merely energy-producing organelles but also regulate metabolism, apoptosis, and inflammation. Recent studies have reported that mitochondria can be transferred between cells, and accumulating evidence suggests that this phenomenon is functionally relevant in the tumor context. Mitochondrial transfer is mediated by multiple routes such as tunneling nanotubes and extracellular vesicles. These pathways are regulated by Miro1/2, connexin 43, ICAM-1, VCAM-1, and intracellular reactive oxygen species. Within the tumor microenvironment, mitochondrial transfer from surrounding cells to tumor cells may serve as a mechanism by which tumor cells adapt to hostile metabolic conditions and evade therapeutic pressure. Furthermore, mitochondrial transfer from tumor cells to T cells in the tumor microenvironment reportedly impairs antitumor immunity. Based on these findings, novel therapeutic strategies targeting mitochondrial transfer are under investigation. Future challenges include the development of specific and safe methods to manipulate mitochondrial transfer invivo. Understanding mitochondrial transfer and its regulation may offer new avenues to overcome resistance and improve cancer outcomes.

ABSTRACTWe investigated immunologic biomarkers that predict outcomes of patients with previously treated metastatic non‐small cell lung cancer who were enrolled in the J‐TAIL study, a prospective, observational study of atezolizumab monotherapy. Of 262 patients participating in the J‐TAIL exploratory study, peripheral blood mononuclear cells were obtained from 51 patients and analyzed by T‐cell fractionation analysis using Helios mass cytometry and serum proteomics analysis. Following treatment with atezolizumab, an increase in programmed cell death‐1 (PD‐1)‐expressing CD8 and CD4 T‐cell populations was observed. A more pronounced increase in PD‐1 expression was seen in T cells from patients whose progression‐free survival (PFS) was 100 days or longer compared with those with shorter PFS. The proximity extension assay, which is highly sensitive multiplex analysis technology that combines antibody‐based affinity assays with next‐generation sequencing, showed a significant increase in FOXO1, possibly in response to precursor‐exhausted T‐cell population activation. Immune‐related adverse events were associated with a high percentage of PD‐1‐positive cells on effector memory CD8 T cells, which was thought to be accompanied by extremely high CD8 T‐cell activation. Further analysis distinguished poor prognosis populations with significant differences in CD62Lhigh Th7R and CXCR3+ component of Th7R (CXCR3+ Th7R) within the population with PFS < 50 days. Patients with low Th7R or CXCR3+ Th7R percentages prior to atezolizumab treatment had significantly poorer overall survival. These findings provide valuable insights regarding T‐cell kinetics and biomarkers in atezolizumab therapy and may offer promising directions for future research.Trial Registration: UMIN Clinical Trials Registry: UMIN000033133 and UMIN000035567; ClinicalTrials.gov: NCT03645330

Tumor mutational burden (TMB) is a key biomarker for predicting the response to immune checkpoint inhibitors (ICIs). However, its predictive accuracy in real-world clinical practice, particularly in Asian populations, remains inadequately evaluated. We addressed this issue by analyzing real-world data from 63,952 patients registered in the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) database, which integrates genomic and clinical information from Japanese patients with various advanced solid tumors. We assessed the therapeutic efficacy of pembrolizumab in 1899 patients who underwent one of three comprehensive genomic profiling tests: FoundationOne CDx, the OncoGuide NCC Oncopanel System, or the GenMine TOP Cancer Genome Profiling System. Based on the reported TMB values, patients were classified as TMB-high (≥ 10 mutations per megabase) or TMB-low (< 10 mutations per megabase). The objective response rate (ORR) among 946 TMB-high patients exceeded 30% and was significantly higher than that observed in 953 TMB-low patients (16.8%, p < 0.001). Notably, patients with borderline TMB values (10 to less than 13 mutations per megabase) exhibited relatively modest responses (20.8%). The ORR improved when hotspot mutations were excluded from the TMB calculation, suggesting that this adjustment enhances the predictive accuracy of TMB. These findings support the clinical utility of TMB as a biomarker for predicting ICI response in routine oncology practice. In particular, excluding hotspot mutations from TMB calculations may improve response prediction in patients whose TMB values are near the threshold.

Esophageal squamous cell carcinoma (ESCC) remains a leading cause of cancer-related mortality, with early detection being challenging. Although endoscopic screening can aid in diagnosis, its invasiveness and cost limit widespread compliance. To address this, we developed and validated a non-invasive diagnostic panel based on urinary exosomal microRNAs (miRNAs) for early ESCC detection. Urine samples were prospectively collected from ESCC patients and healthy controls across five institutions, and exosomal miRNA profiles were obtained using small RNA sequencing. A diagnostic panel was constructed using machine learning with recursive feature elimination in a proof-of-concept (POC) cohort comprising 99 ESCC and 93 control samples, and its performance was evaluated by five-fold cross-validation. This panel was subsequently tested in a blinded validation cohort of 50 ESCC and 61 control samples. In the POC cohort, the multi-miRNA panel achieved an area under the curve (AUC) of 0.90. In the validation cohort, the AUC was 0.85 (95% CI: 0.77-0.92), with 84% sensitivity and 66% specificity. The panel showed high sensitivity across disease stages-100% for Stage 0, 91% for Stage I, and 73% for Stages II-IV-and its performance was not significantly affected by sex, body mass index, alcohol use, or smoking. Furthermore, in early-stage cases, the diagnostic score significantly declined after treatment (p = 0.026). These findings suggest that the urinary exosomal miRNA panel may offer a practical screening approach for the early detection of ESCC.

RETRACTION: YaoQ., TuC., LuD., ZouY., LiuH., and ZhangS., “Clinicopathological Significance of the MicroRNA‐146a/WASP‐Family Verprolin‐Homologous Protein‐2 Axis in Gastric Cancer,” Cancer Science108, no. 7 (2017): 1285–1292, 10.1111/cas.13254.28387985The above article, published online on 07 April 2017 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor‐in‐Chief, Masanori Hatakeyama; the Japanese Cancer Association; and John Wiley & Sons Australia, Ltd. The retraction has been agreed upon following concerns about the reliability of data and images raised by a third party. An investigation also identified duplication of images between Figures 2b and 2c. The authors did not respond to invitations to comment on these concerns nor provide supporting data to support the findings. The editors therefore consider the results and conclusions of this article unreliable. The authors did not respond to our notice of retraction.

Antibody-drug conjugates (ADCs) are emerging as a promising class of targeted cancer therapy. Trastuzumab deruxtecan (T-DXd), a human epidermal growth factor receptor 2 (HER2)-directed ADC, has demonstrated clinical efficacy in HER2-positive gastric and breast cancers, as well as in HER2-mutant non-small cell lung cancer. However, the development of acquired resistance limits their long-term efficacy. To elucidate the resistance mechanism, we established T-DXd-resistant cell lines derived from HER2-amplified gastric xenografts (N87 acquired resistance [AR]) and leptomeningeal carcinomatosis (Calu-3 AR) lung cancer cells. N87 AR cells exhibited cross-resistance to T-DXd, payload DXd, and topoisomerase I inhibitor SN-38 despite preserved HER2 expression and intact drug internalization. As payload resistance-related molecules, ATP-binding cassette (ABC) transporter ABCG2 and ABCB1 were markedly upregulated in N87 AR and Calu-3 cells, respectively. Inhibition of ABCG2 and ABCB1 in N87 AR and Calu-3 cells, respectively, through siRNA-mediated knockdown restored T-DXd sensitivity in both models. As a strategy to overcome resistance, pharmacological inhibitors of ABCG2 and ABCB1 restored the T-DXd sensitivity of N87 AR and Calu-3 cells, respectively. Moreover, BB-1701, a novel HER2-ADC containing eribulin as a payload, to which N87 AR cells are sensitive, exhibited antitumor effects in N87 AR cells invitro and invivo. These findings indicate that ABC transporter-mediated drug efflux is an important mechanism underlying T-DXd resistance in HER2-positive gastric and lung cancer models. Furthermore, our study suggests that both targeting drug efflux pathways and utilizing alternative payloads may be effective strategies for overcoming T-DXd resistance in HER2-positive gastric and lung cancers.

Advanced hepatic fibrosis is a major risk factor for cirrhosis and hepatocellular carcinoma (HCC), and it is required to identify a key mediator involved in intratumoral fibrosis and HCC development. Transcriptomic analysis of 372 HCC samples using publicly available datasets revealed that SPP1 was significantly upregulated in fibrotic HCC tissues and associated with unfavorable outcomes. Immunohistochemical analysis of 103 HCC tissues and single-cell RNA sequencing (scRNA-seq) analysis of 228,564 live cells identified SPP1 overexpression in HCC cells, which strongly correlated with intratumoral fibrosis. In xenograft models, HCC cells with SPP1 overexpression (SPP1-OE) exhibited enhanced fibrosis and tumor growth. Coculture assay demonstrated that SPP1-OE cells stimulated hepatic stellate cells (HSCs), and gene set enrichment analysis and differential gene expression analysis elucidated the activation of the Hedgehog signaling pathway and upregulation of GLI1 in HSCs. Cell-cell interaction prediction analysis using scRNA-seq data suggested that SPP1-CD44 signaling transduction might contribute to HSC activation. Pharmacological inhibition of GLI1 with the SMO inhibitor vismodegib suppressed HSC activation invitro and reduced fibrosis and tumor growth invivo. These findings indicate that SPP1 promotes intratumoral fibrosis and HCC progression through the SPP1-CD44-GLI1 axis, highlighting its potential as a prognostic biomarker and therapeutic target. Inhibition of SPP1-CD44-Hedgehog signaling may provide a promising strategy to mitigate fibrosis and improve HCC patient outcomes.