The non-canonical (NC) NF-κB pathway controls peripheral B-cell survival and follicular organization, pointing to a regulatory role during active adaptive immune responses. Here, we show that NC NF-κB activity is selectively attenuated in human germinal center B cells (GCBs), the population required to generate high-affinity antibodies, while remaining elevated in effector B cells. Accordingly, enforced NC NF-κB activation in murine B cells resulted in near-complete loss of GCB and high-affinity antibody production following immunization. These effects were primarily driven by NC NF-κB-induced reshaping of the immune microenvironment: activated B cells secreted IL-10, triggering premature expansion of regulatory T cells, limiting T cell help, and suppressing germinal center responses. Blocking IL-10 signaling was sufficient to normalize the niche and restore GCB. Concurrently, NC NF-κB activation promoted rapid B-cell differentiation into low-affinity antibody-secreting cells. Together, these findings identify NC NF-κB as a tunable rheostat linking B-cell signaling, immune-niche control, and humoral immunity.

ABSTRACT Background Intratumor heterogeneity (ITH), characterized by the coexistence of genetically distinct subclones within a tumor, has been associated with adverse clinical outcomes in various cancers. However, the clinical and biological implications of ITH in diffuse large B‐cell lymphoma (DLBCL) are still incompletely understood. Materials & Methods In this study, we applied a SNP‐array–based approach to assess the clonal complexity in formalin‐fixed, paraffin‐embedded tumor specimens obtained from newly diagnosed patients with advanced‐stage DLBCL (n = 74) by calculating the clonal composition (CC) number. Rseults Patients with Poly‐CC tumors (CC ≥ 1), which accounted for 79.7% of the cases, had a 5‐year event‐free survival rate of 38.9%, compared with 69.1% in those with Mono‐CC tumors (CC = 0) (Log‐rank p = 0.0520). This association reached statistical significance in the activated B‐cell (ABC) subtype (n = 35, Log‐rank p = 0.0450) but not in the germinal center B‐cell (GCB) subtype (n = 30, Log‐rank p = 0.910). Gene set enrichment analysis revealed upregulation of cell cycle–related pathways in Poly‐CC tumors, consistent with the significantly higher Ki‐67 positivity rate than in Mono‐CC tumors, as confirmed by immunohistochemistry (p = 0.00227). Within the ABC subtype, Poly‐CC (Poly‐ABC) tumors exhibited more differentiated transcriptional states and enrichment of IRF4‐associated gene signatures as compared with Mono‐CC (Mono‐ABC) tumors. Conversely, IFN‐γ and IFN‐α response pathways and the IL‐6/JAK‐STAT3 signaling pathway were markedly suppressed in the Poly‐ABC tumors. Furthermore, Poly‐ABC tumors carried a significantly higher number of pathogenic mutations as compared with Mono‐ABC tumors (p = 0.0147). Conclusion These results suggest that clonal complexity captures tumor‐intrinsic features and biological diversity in DLBCL, especially in the ABC subtype, offering novel insights into the disease pathogenesis.

TableS1. Patient characteristics of the CHL study training cohorts. Table S2. Gene list for the targeted sequencing panel and HLGen. Table S3 Patient Demographic and molecular alterations. Table S4. HLGen correlation with Age and EBV in Training and Validation cohort. Table S5. Antibodies used for immunohistochemistry staining. Table S6. Differential gene expression analysis followed by gene ontology analysis in L-428 model. Table S7. Differential gene expression analysis followed by gene ontology analysis in U-HO1 model + IL-3. Table S8 Differential gene expression analysis followed by gene ontology analysis in U-HO1 model + IL-5. Table S9 Gene expression changes across all three experimental models. Table S10. Classification methods for HLGen. Table S11 HLGen Prediction in Training cohort. Table S12 HLGen Prediction in Stanford cohort (Alig and colleagues, Nature 2024). Table S13. Antibodies used for immunohistochemistry staining. Table S14. IMC Clustering Strategy. Table S15. Antibodies used for flow cytometry staining. Table S16. Antibodies used for Western blotting.

Figure S1. Co-occurrence of mutation in CHL. Figure S2. STAT6 copy number gain. Figure S3. Frequent mutations according to key clinical features. Figure S4. Copy number alterations according to EB Virus (EBV) status on HRS cells. Figure S5. Multivariable analyses on thymic mutation. Figure S6. Coding mutation count according to key clinical features in CHL. Figure S7. Impact of molecular profile on survival in CHL. Figure S8. STAT6 mutations in CHL. Figure S9. Impact of molecular profile on survival in elderly CHL. Figure S10. MHC status on HRS cells and their molecular correlates. Figure S11. Molecular Subgroups of CHL. Figure S12. Correlation between molecular subtypes and key clinical features. Figure S13. Molecular subtype and progression free survival (PFS) in Hodgkin lymphoma. Figure S14. Overview of the imaging mass cytometry (IMC) analysis and panel. Figure S15. Spatial tumor-microenvironment correlates with molecular subtype in CHL. Figure S16. Membrane map depicting major immune cell populations in each molecular subgroup. Figure S17. Correlation between molecular subtypes and key features. Figure S18. Evidence of CSF2RB mutant allele expression at the protein level in L-1236 KO model. Figure S19. CSF2RB mutations confer cytokine-dependent gain-of-function signaling in the L-428 model. Figure S20. CSF2RB mutations promote activation of the STAT5 signaling pathway. Figure S21. Co-expression of CSF2RB-WT and E788* mutant enhances downstream cytokine responses. Figure S22. Characterization of extrinsic phenotypes of CSF2RB mutations. Figure S23. Tumor-microenvironment characterization with molecular subtype in CHL. Figure S24. Cohort and study design overview for the HLGen development. Figure S25. Oncoplot of the CHL samples from Stanford ctDNA cohort (n = 293), with clinical annotation according to molecular subtype. Figure S26. Impact of feature list reduction on HLGen classifier performance. Figure S27. Graphical summary of molecular subtypes and their clinical and tumor-microenvironment ecosystem correlates in classic Hodgkin lymphoma. Figure S28. GeoMx analyses on CD30+ HRS cells. Figure S29. Segmentation on Imaging Mass Cytometry. Figure S30. Gating Strategy of regulatory T cell population.

OBJECTIVES:To validate the diagnostic performance of the HScore for Still's disease (SD)-associated macrophage activation syndrome (MAS; SD-MAS) in adults compared with those of the HLH-2004 diagnostic criteria used with modifications (HLH-04) and the 2016 EULAR/ACR/PRINTO classification criteria for systemic juvenile idiopathic arthritis-associated MAS (MAS-2016). METHODS:This multicentre case-control study, conducted at three medical centres in Japan between 2004 and 2023, enrolled patients ≥16 years with active SD and allocated them into SD without MAS and SD-MAS groups by an expert panel. For each patient, we calculated the HScore, HLH-04, MAS-2016, and modified HScore, which excluded haemophagocytosis on bone marrow aspirate. Receiver operating characteristic curve analysis was used to assess the discriminative ability of each criterion. Logistic regression analysis was performed separately for 'model-1' (HScore and HLH-04) and 'model-2' (MAS-2016 and modified HScore). RESULTS:This study included 86 patients with SD, 25 of whom had SD-MAS. The HScore showed the best area under the curve at 0.991 (95% confidence interval [CI]: 0.977-1.000), with a cut-off value of 192 (sensitivity, 96.0%; specificity, 96.7%). The optimal cut-off for the modified HScore was 171 (sensitivity, 92.0%; specificity, 83.6%). Multivariate analysis identified only the HScore in model-1 (odds ratio [OR]: 1.271; 95% CI: 1.006-1.606), whereas both MAS-2016 (OR: 4.249; 95% CI: 1.636-11.041) and modified HScore (OR: 1.066; 95% CI: 1.017-1.118) were identified in model-2. CONCLUSIONS:The HScore and modified HScore could be useful tools for diagnosing SD-MAS in adults with and without bone marrow aspiration, respectively.

T follicular helper (TFH)-derived peripheral T-cell lymphomas (PTCLs) harbor frequent mutations in epigenetic regulators and are sensitive to epigenetic therapies. The histone deacetylase inhibitor tucidinostat demonstrated efficacy in relapsed/refractory PTCL, especially angioimmunoblastic T-cell lymphoma (AITL), in a phase IIb trial; however, the lack of TFH phenotyping has prevented assessment of the predictive value of this phenotype across a broader PTCL spectrum. Therefore, we retrospectively analyzed patients originally diagnosed with AITL or PTCL not otherwise specified (NOS) based on 2008 World Health Organization criteria who participated in the aforementioned trial. TFH phenotype was defined as the expression of ≥ 2 TFH markers. Among the 23 evaluable patients, the TFH group (n = 17) included six with AITL and 11 with PTCL-NOS exhibiting TFH features, and the non-TFH group included six patients with PTCL-NOS. The objective response rate was numerically higher in the TFH group (12/17, 70.6

Chronic kidney disease (CKD) is a significant comorbidity in patients with rheumatoid arthritis (RA). The relative contributions of inflammatory and traditional renal risk factors to CKD progression remain unclear. We retrospectively analyzed 601 RA patients. Renal function and urinary abnormalities were assessed using creatinine-based estimated glomerular filtration rate (eGFR) and urinary albumin. We examined the factors associated with high or very high CKD risk in KDIGO heatmap and progression of CKD stage over five years using two models: logistic regression and Cox proportional hazards models. Furthermore, Propensity score methods were used to assess the association between methotrexate (MTX) use and CKD stage progression. CKD stage progression occurred in 106 patients. Both inflammatory and traditional renal risk factors were associated with high or very high CKD risk. In Cox analyses, age, lower baseline eGFR, anemia, and CRP ≥0.5 mg/dL were associated with CKD stage progression. In patients with baseline eGFR ≥60 mL/min/1.73 m2, CRP ≥0.5 mg/dL was independently associated with progression, whereas proteinuria and albuminuria were more relevant in patients with baseline eGFR <60 mL/min/1.73 m2. After adjusting for confounding variables using propensity score matching, there was no association between MTX use and an increased risk of kidney stage progression. Risk factors for CKD progression in RA may differ according to baseline eGFR. In patients with preserved eGFR, residual inflammation appears to be a relevant factor. In contrast, proteinuria, albuminuria, and anemia are more significant in patients with reduced eGFR.

The tissue architecture of classic Hodgkin lymphoma (cHL) is unique among cancers and is characterized by rare malignant Hodgkin and Reed-Sternberg cells that coevolve with a complex ecosystem of immune cells in the tumor microenvironment (TME). The lack of a comprehensive systems-level interrogation has hindered the description of disease heterogeneity and clinically relevant molecular subtypes. In this study, we employed an integrative, multimodal approach to characterize cHL tumors using malignant cell sequencing, spatial transcriptomics, and imaging mass cytometry. We identified four molecular subtypes (CST, CN913, STB, and CN2P), each characterized by distinct clinical features, mutational patterns, malignant cell gene expression profiles, and spatial architecture involving immune cell populations. Functional modeling of CSF2RB mutations, a characteristic feature of the CST subtype, revealed dysregulated oncogenic signaling and unique TME cross-talk. These findings highlight the significance of multidimensional profiling in elucidating patterns of molecular alterations that drive immune ecosystems and underlie therapeutically exploitable vulnerabilities. SIGNIFICANCE:Our systematic and comprehensive genomic and spatially resolved profiling of Hodgkin lymphoma revealed a paradigmatic link between a genetic disease subtype and TME composition and function. Insights into mutation-driven mechanisms of deregulated cytokine signaling will pave the way for therapeutic interventions that interfere with oncogenic signaling and cellular ecosystems in cancer.

ABSTRACT:Classical Hodgkin lymphoma (CHL) is characterized by a complex tumor microenvironment (TME) that supports disease progression. Although immune cell recruitment by Hodgkin and Reed-Sternberg (HRS) cells is well documented, the role of nonmalignant B cells in relapse remains unclear. Using single-cell RNA sequencing (scRNA-seq) on paired diagnostic and relapsed CHL samples, we identified distinct shifts in B-cell populations, particularly an enrichment of naïve B cells and a reduction of memory B cells in early-relapse CHL compared to late-relapse and newly diagnosed CHL. The enrichment of naïve B cells in early relapse biopsies was confirmed in independent validation cohorts using scRNA-seq and immunohistochemistry. Notably, naïve B cells in early-relapse samples exhibited high expression of LGALS9, an immunosuppressive gene encoding galectin-9, which binds to HAVCR2 (T-cell immunoglobulin and mucin domain-containing protein 3 [TIM-3]) on regulatory T cells (Tregs). Cell-cell interaction analysis revealed the importance of interactions between LGALS9+ naïve B cells and HAVCR2+ Tregs in the early-relapse setting. Spatial analysis by imaging mass cytometry confirmed close proximity of galectin-9-positive naïve B cells with TIM-3+ CD4+ T cells and HRS cells, pointing to their role in shaping an immunosuppressive niche. Our findings highlight a previously unrecognized population of galectin-9-positive naïve B cells with immunoregulatory potential in early-relapse CHL and provide new insights into the spatial and transcriptional architecture of the relapsed TME in CHL.

Abstract Histological examination of follicular lymphoma (FL) biopsies remains the cornerstone for diagnostic grading of FL. Single-cell sequencing approaches, while transcriptomically rich, require tissue dissociation and lose the native spatial context that underpins FL transformation to diffuse large B-cell lymphoma (DLBCL). To investigate the spatial interplay between malignant B-cells and the tumour microenvironment (TME) across disease states, we performed subcellular single-cell spatial transcriptomics and spatial proteomics on 12 paired pre/post-transformation samples and 10 non-transforming FL controls, integrated with matched single-cell whole genome sequencing (scWGS). Our analysis reveals that transformation is accompanied by a shift toward B-cell-predominant stromal and immunosuppressive cellular neighbourhoods, where the magnitude of expansion correlates with time to transformation. Prior to transformation, immunomodulatory Galectin-9 interactions move from the intra-follicular core to the extra-follicular space. Integration with scWGS demonstrates that high copy-number instability in malignant B-cells is associated with reduced supportive T-cell niches and intensified immunoregulatory crosstalk at the transformed state. Collectively, our multi-omic analysis characterizes TME remodeling during FL transformation, contributing to a refined disease evolution model.

Objectives This study aimed to compare 24-month drug retention between standard-dose and reduced-dose Janus kinase inhibitors (JAKi) in rheumatoid arthritis (RA) and to examine whether poor prognostic factor (PPF) burden and renal function modify treatment persistence, with primary inference restricted to patients with preserved renal function, in whom reduced dosing reflects discretionary clinical decision-making. Methods We conducted a multicentre observational study using a Japanese real-world registry of patients with RA who initiated JAKi between 2013 and 2025. Patients were classified according to their initial JAKi dosing strategy. Primary analyses were performed in patients with preserved renal function. Propensity score matching was used to adjust for confounding by indication. Drug retention over 24 months was assessed using Kaplan-Meier analyses and Cox proportional hazards models, with prespecified stratification by PPF burden (0-2 vs 3-4). Supportive analyses were conducted in patients with reduced renal function. Results Among 1135 patients, 24-month drug retention was comparable between standard-dose and reduced-dose JAKi in the matched cohort with preserved renal function. Disease activity improved similarly in both groups, and glucocorticoid use remained low without compensatory escalation. Reduced dosing performed comparably in patients with low PPF burden, whereas standard-dose initiation showed more favourable persistence in patients with multiple PPFs. In patients with reduced renal function, standard dosing was associated with higher drug retention. Conclusions In patients with preserved renal function, reduced-dose JAKi initiation was associated with 24-month treatment persistence comparable with standard dosing. Findings in PPF-stratified analyses and in patients with reduced renal function should be interpreted cautiously and warrant further investigation.

Sarilumab (SAR), an interleukin-6 receptor inhibitor (IL-6Ri), and Janus kinase inhibitors (JAKi) are approved options for rheumatoid arthritis (RA) when methotrexate (MTX) cannot be used. Real-world evidence for MTX-free monotherapy remains limited. We conducted a multicenter retrospective cohort study of RA patients receiving SAR or JAKi as MTX-free monotherapy. To reduce confounding, 1:1 propensity score matching was performed in the overall cohort (n = 252, 126 per group) and separately within treatment-line strata: Phase 2 first-line biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs: 45 per group), Phase 3 second-line b/tsDMARDs (53 per group), and Phase 3 ≥ third-line b/tsDMARDs (47 per group). Outcomes over 12 months included drug retention, change in Clinical Disease Activity Index (CDAI), glucocorticoid (GC) tapering and discontinuation, low disease activity (LDA, CDAI ≤ 10), and safety profiles. Predictors of LDA were evaluated with logistic regression. This multicenter real-world. Across matched strata by prior b/tsDMARDs, retention and CDAI change did not differ significantly between SAR and JAKi through 12 months. When classified by cause, adverse events (AEs)-related discontinuation was higher with JAKi, yielding lower AE-specific retention. Both groups demonstrated GC sparing overtime, with a greater increase in GC discontinuation for SAR than for JAKi in Phase 2. Baseline predictors of achieving LDA at 12 months included higher C-reactive protein (CRP) and platelet count (Plt) in both groups, with additional associations of younger age and lower hemoglobin (Hb) in the SAR. In safety analyses, overall AEs were less frequent with SAR than with JAKi, driven by lower risks of infection including herpes zoster, while other categories were similarly infrequent. SAR and JAKi showed no statistically significant differences in 12-month retention or disease control in MTX-free monotherapy settings. Higher CRP and Plt with lower Hb, particularly in younger patients, identified better response to SAR and support biomarker guided selection between IL-6Ri and JAKi. In Phase 2, GC discontinuation with SAR suggests a practical strategy to reduce AEs while maintaining efficacy. Prospective studies should validate these findings and define actionable thresholds.

OBJECTIVES:Glucocorticoid (GC)- and MTX-sparing strategies are clinically important in RA, yet comparative real-world evidence for sarilumab (SAR) vs Janus kinase inhibitors (JAKi) is limited. Whether treatment effects differ by age at onset-late-onset RA (LORA) vs young-onset RA (YORA)-also remains unclear. This study aimed to compare the effectiveness and safety of SAR and JAKi in patients with LORA and YORA. METHODS:We conducted a multicentre real-world cohort study of adults with RA initiating SAR or a JAKi. Outcomes over 12 months included change from baseline in MTX dose (ΔMTX, mg/week) and GC dose (ΔGC, mg/day), cumulative treatment discontinuation and change in Clinical Disease Activity Index (CDAI). Analyses were performed within LORA and YORA strata, and propensity score matching (PSM) was applied separately in each stratum to balance baseline characteristics. Sensitivity analyses were conducted in the matched cohorts. RESULTS:Both SAR and JAKi were associated with progressive tapering of concomitant MTX and GC during follow-up. SAR was associated with a higher frequency of MTX discontinuation compared with JAKi. In contrast, GC discontinuation and CDAI improvement were broadly similar between treatments across age strata and MTX subgroups. Findings were consistent after PSM and in sensitivity analyses within both LORA and YORA. CONCLUSION:In routine clinical practice, SAR and JAKi support de-escalation of concomitant therapy. SAR may permit earlier MTX withdrawal without loss of disease control, with comparable GC tapering and disease activity improvement in both LORA and YORA.

Background: FLT3 mutations, including internal tandem duplication (ITD) and tyrosine kinase domain (TKD) point mutations, represent common genetic alterations in acute myeloid leukemia (AML), with FLT3-ITD associated with poor prognosis. Although FLT3 tyrosine kinase inhibitors (TKIs), such as quizartinib (Quiz) and gilteritinib, have improved clinical outcomes, secondary TKD mutations, particularly the gatekeeper mutation F691L, confer significant resistance. We previously demonstrated that chlorpromazine (CPZ), an antipsychotic drug, inhibits clathrin-mediated endocytosis and selectively suppresses the growth of cancer cells harboring mutant receptor tyrosine kinases. Methods: In this study, we examined the efficacy of CPZ in overcoming TKI resistance using Ba/F3 cells expressing FLT3-ITD or FLT3-ITD/F692L, the murine analog of F691L. Results: Quiz inhibited proliferation of FLT3-ITD cells but was ineffective against FLT3-ITD/F692L cells. CPZ suppressed growth in both cell types. Co-treatment with CPZ and Quiz exhibited synergistic effects in FLT3-ITD cells, but not in FLT3-ITD/F692L cells. CPZ reduced STAT5 phosphorylation and modulated downstream signaling in FLT3-ITD cells, while only partially affecting STAT5 in FLT3-ITD/F692L cells. Expression of constitutively active STAT5 partially rescued CPZ-induced growth inhibition. Conclusions: These findings suggest that STAT5 suppression is a key mechanism of CPZ’s antileukemic activity and support its potential as a therapeutic strategy for FLT3-ITD-positive AML.

Classic Hodgkin lymphoma (CHL) is unique among most malignancies as the malignant Hodgkin and Reed–Sternberg (HRS) cells (0.1-5%) are vastly outnumbered by a heterogeneous population of reactive, non-neoplastic cells within the tumor-microenvironment (TME). CHL exhibits a bimodal age distribution, with peaks in adolescents and young adults (AYAs) aged 15-39 years and older adults (over 50 years). Although a previous bulk gene expression-based study (Johnston et al., Blood 2022) suggested differences in the TME transcriptional profiles between pediatric CHL and adult CHL, the study did not take into account for key factors such as cellular interactions, specific expression features of HRS cells, or the spatial architecture of the TME. A deeper understanding of the age-related TME ecosystem is essential for advancing our knowledge of the unique pathogenesis of pediatric CHL and for developing biomarker-driven targeted therapies. In this study, we aim to elucidate distinct TME ecosystems in pediatric CHL by applying single-cell and spatial technology. We performed single-nuclei RNA sequencing (snRNA-seq) on formalin-fixed, paraffin-embedded (FFPE) tissue samples from a total of 27 patients, including 11 adult (19-39 years) and 8 pediatric HL patients (10-16 years) with Epstein-Barr virus (EBV)-negative nodular sclerosis HL, as well as 4 adult and 4 pediatric reactive lymph nodes (RLN) serving as normal controls. We merged the expression data from all cells and used the louvain clustering algorithm to identify major cell types and functional cellular subsets and defined each immune cell population based on marker expression. We also performed spatial transcriptomics using the CosMx™ Spatial Molecular Imager with the human 6K discovery panel, applied to tissue microarray (TMA) from 75 pediatric CHL patients (3-18 years) enrolled in the Children's Oncology Group (COG) AHOD0031 trial. We utilized transcriptomic signatures of cell types identified by snRNA-seq to annotate major cell types in CosMx data by a label transfer approach. For each cell type in the TME, we calculated a ‘spatial score’ (Aoki et al., J Clin Oncol 2024), spatial cell enrichment score of a given cell type as the distance to the five nearest neighbor cells, capped at the spatial interaction range (50µm). We analyzed 119,335 cell transcriptomes after quality control filtering in the snRNA-seq data. Unsupervised clustering revealed 20 phenotypically distinct clusters. When comparing age-related distributions of immune cell phenotypes, CD8+ T cells, NK cells, naïve T cells, CD4+ T cells and B cells were significantly more predominant in pediatric CHL compared to adult CHL (p < 0.001). In contrast, myeloid cells including monocytes, macrophages, and dendritic cells, were more enriched in adult CHL than in pediatric CHL (p < 0.001). In particular, we identified a subcluster, myeloid-C2, characterized by high CXCL13and CD68expression, which represent the most distinct population in adult CHL. Among the immune populations enriched in the TME of pediatric CHL, we further investigated the CD8+ T cell subsets, as the role of CD8+ T cells in CHL remains incompletely understood. We first performed differential gene expression analysis between cells from pediatric and adult CHL samples within the CD8+ T cell cluster, identifying CCL5 as the one of the most up-regulated genes in pediatric CHL. We further identified a pediatric HL enriched subcluster, CD8-C2, characterized by high CCL5 and LAG3 expression. The CD8-C2 cluster exhibited high expression of cytotoxicity, IFN response, and exhaustion signatures. Notably, the cell-to-cell communication tool, Cell-Chat, revealed a significant interaction between the CCL5+ (CD8-C2) and CCR4(HRS cells) axis (p<0.001). CCR4+ HRS cells were significantly more enriched in pediatric CHL compared to adult CHL (p < 0.001). To validate these findings, we analyzed CosMx data comprising 557,742 cells. By calculating a spatial score, we confirmed that CCR4+ HRS cells were significantly more proximal to CCL5+ CD8+T (CD8-C2) cells (p=0.02), but not to CCL5- CD8+T cells. Multimodal transcriptional and spatial profiling reveals a distinct TME in pediatric CHL. We identified the interaction of CCR4+ HRS cells with ligand-expressing CCL5+ CD8+ T cells as a prominent crosstalk axis in pediatric CHL, with potential Iimplications for novel therapeutic approaches.

ABSTRACT:Disease-defining signatures in lymphomas, driven by intricate molecular mechanisms, have advanced molecular taxonomies, refined classification, and may guide clinical management; however, the role of these signatures in driving disease hallmarks, including subtype-specific organotropism, remains largely unexplored. Primary mediastinal large B-cell lymphoma (PMBCL) is an exemplary lymphoma characterized by disease manifestations in the thymic niche, unique genetic alterations, and immune escape. Here, we identified interferon regulatory factor 4 (IRF4)-C99R mutations uniquely occurring in PMBCL through mutational meta-analysis of large-scale data sets. By integrating multiomics approaches with genome editing in PMBCL cells, we revealed that IRF4-C99R contributes to a differentiation block phenotype. Specifically, we showed that IRF4-C99R reduces its binding to the interferon-stimulated response element (ISRE) motif within PRDM1, encoding a key transcriptional regulator of B-cell differentiation, resulting in decreased PRDM1 expression. Additionally, IRF4-C99R suppresses Traf2 and Nck-interacting kinase, a key interferon gamma (IFN-γ) pathway regulator, by impairing ISRE motif binding, thereby reducing IFN-γ signaling and increasing thymus and activation-regulated chemokine (TARC) expression, which drives TARC-mediated chemotaxis of T regulatory cells. We also revealed that IRF4-C99R upregulates ephrin type-B receptor 1 (EPHB1) through noncanonical activating protein 1-IRF composite motif binding and showed that overexpression of EPHB1 in an immunocompetent syngeneic lymphoma model influenced organotropism to favor thymic localization, without affecting overall tumor burden. IRF4-C99R mutation-induced phenotypes were validated in primary PMBCL tissues using single-nuclei RNA sequencing, confirming that the molecular mechanisms observed in vitro align with the pathophysiology of PMBCL in patients. Together, these findings demonstrate how a single genetic mutation orchestrates the coordinated regulation of hallmark traits including thymus-specific tropism in PMBCL.

Polatuzumab vedotin plus rituximab, cyclophosphamide, doxorubicin, and prednisone (Pola-R-CHP) was approved in Japan for the treatment of previously untreated diffuse large B-cell lymphoma (DLBCL) in 2022, based on findings of the POLARIX study (NCT03274492). Reports on real-world usage of Pola-R-CHP are lacking. Here we report safety and response rates at end of treatment (EOT) for Pola-R-CHP in Japan from the real-world observational POLASTAR study (jRCT1071220082). Patients (≥ 18 years) with previously untreated DLBCL who were scheduled to receive Pola-R-CHP were enrolled. The primary endpoint was overall survival. As of December 20, 2023, the full analysis set (FAS) included 192 of the initial 199 patients enrolled. Median age was 71.0 years (range 30–91). In the FAS, 99 (51.6%) patients had Grade ≥ 3 adverse events (AEs), 29 (15.1%) had serious AEs, and 15 (7.8%) discontinued polatuzumab vedotin due to AEs. In the efficacy-evaluable population at EOT ( n = 141), the overall response rate was 95.0% [95% confidence interval (CI), 90.1–97.6], and the complete response rate was 87.9% (95% CI, 81.5–92.3). These results are consistent with published data from POLARIX. The POLASTAR study is ongoing; the recruitment target of 500 patients has been reached. Clinical trial registration: Japan Registry of Clinical Trials (jRCT1071220082).

ABSTRACT:No standard of care for older patients with aggressive adult T-cell leukemia/lymphoma (ATL) has been established. We evaluated the efficacy of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) every 2 weeks with mogamulizumab (Moga; Moga-CHOP-14) for older patients with untreated ATL. In this multicenter phase 2 trial, patients aged ≥66 years and those aged 56 to 65 years ineligible for transplantation received 6 cycles of Moga-CHOP-14, followed by 2 cycles of Moga monotherapy. The primary end point was 1-year progression-free survival (PFS). Secondary end points were the complete response (CR) rate, overall response rate (ORR), overall survival (OS), 1-year event-free survival (EFS), and safety. We also investigated the impact of CC chemokine receptor 4 (CCR4) mutation and Moga-associated cutaneous adverse events (cAEs) on PFS and OS. The study protocol was amended to allow the dosing interval to be extended to 21 days at the physician's discretion. Among 48 evaluable patients, the 1-year PFS was 36.2% (90% confidence interval, 24.9-47.6), with a median follow-up of 1.6 years. The 1-year OS and EFS were 66.0% and 29.9%, respectively. CR and ORR were 64.6% and 91.7%. No unexpected toxicities were observed. Of 47 patients who received ≥2 cycles of CHOP, 20 (42.6%) received CHOP-14, among whom 12 (25.5%) completed 6 cycles. CCR4 mutation and Moga-associated cAEs were associated with better OS. This study showed that Moga-CHOP significantly improved PFS, although the optimal interval for CHOP remains undetermined. Moga-CHOP is now considered a preferable first-line treatment for this patient population. This trial was registered at https://jrct.mhlw.go.jp/en-top as #jRCTs041180130.