Journal for ImmunoTherapy of Cancer

Introduction: Tumor-reactive T cell receptors (TCRs) are promising candidates for the manufacturing of safe and effective adoptive TCR-T cell therapies, but their efficient identification remains a major challenge. We previously established an antigen-agnostic TCR-repertoire analysis workflow that prioritizes candidate TCRs based on intratumoral clonal expansion and high tumor-to-non-tumor (T/N) frequency ratios. Here, we investigated whether T/N-selected clonotypes show independent transcriptional and spatial features consistent with tumor association. Methods: Bulk and single-cell TCR repertoire sequencing of paired tumor and adjacent non-tumor tissues was used to identify clonotypes with high T/N ratios across 15 cancer cases, comprising six non-small cell lung cancers, five pancreatic cancers, two breast cancers, and two colorectal cancers. Candidate clonotypes were further characterized by paired single-cell TCR and gene expression profiling and, in two PDAC cases, by Xenium spatial transcriptomics to assess their cellular phenotype, spatial localization, and proximity to malignant cells. Results: High T/N ratios consistently marked T cell clonotypes with features of tumor reactivity across the studied solid tumor entities. The analysis included Cluster-A, a lead T cell cluster comprising highly similar TCRs shared among 14 HLA-A*02:01-positive patients in the present cohort. Cluster-A clonotypes were consistently enriched in tumor relative to matched non-tumor tissue, and previous functional studies demonstrated tumor recognition by Cluster-A members. In a focused analysis of a pancreatic cancer case, Cluster-A CD8 T cells were selectively detected in tumor tissue, preferentially localized near malignant epithelial cells, and displayed an antigen-experienced effector-memory phenotype with prominent expression of granzymes A and K (GZMA/GZMK). Importantly, in another PDAC case that lacked Cluster-A clonotypes, these features extended to independent clonotypes, revealing a continuous tumor-association axis in which increasing T/N ratios were associated with progressively closer localization to malignant cells and increased GZMA/GZMK expression. Thus, repertoire enrichment, spatial tumor proximity, and effector-associated transcriptional states converged across independent tumor-enriched clonotypes. Outlook: These findings support the T/N ratio as a robust primary criterion for identifying candidate tumor-reactive TCRs. Integration of single-cell and spatial transcriptomics provides supporting biological evidence of tumor association and a framework for prioritizing therapeutic TCR candidates when functional validation is limited.

Immunotherapy transformed cancer treatment, yet precise correlates of response remain to be defined. While intratumoral follicular helper like (Tfhl) CD4 T cells and IgG1+ B cells have been associated with improved outcomes to PD-1 blockade for hepatocellular carcinoma (HCC), their mechanisms contributing to response are unclear. To address this question, we developed a murine model of HCC and examined CD8, CD4 and B cell responses. Increasing CD4-help sensitizes mice to PD-1 blockade, in a CD4- and CD8-dependent manner. Tumor-specific CD4 T cells contained Tfhl and Th1 populations, and both Bcl6 and T-bet were required for efficacy. Antigen-specific B cells were essential for CD4-helper expansion, yet secretion of antibodies was not required for long-term survival. Thus, B cells are critical for effective immunotherapy, but secreted antibodies are not.

Background Immune checkpoint inhibitor (ICI) therapies have revolutionized oncology, but identifying patients who benefit remains a challenge, particularly in populations where ICIs are not the standard of care, including microsatellite stable colorectal cancer (MSS CRC) and rare solid cancers. We evaluated real-world performance of the Immune Profile Score (IPS), a validated DNA- and RNA-based molecular signature, in these cohorts. Methods In an exploratory analysis, we analyzed two real-world cohorts: 1) MSS CRC; and 2) MSS, tumor mutational burden-low rare solid cancers treated with off-label ICI. IPS-High and IPS-Low were calculated using a previously validated threshold. Cox proportional hazards models were fit to demonstrate prognostic utility for real-world overall survival (rwOS). In MSS CRC, time-to-next-treatment (TTNT) on prior non-ICI therapy was compared to rwOS on subsequent ICI therapy. Results In MSS CRC (n=46), IPS-High patients (13%) demonstrated clinically meaningful improvement in rwOS versus IPS-Low (Median OS: not reached vs 7.3 months; HR = 0.22, 90% CI 0.04-1.16). While IPS was not associated with TTNT on the preceding non-ICI line (HR = 1.07, 90% CI 0.60-1.91), it was associated with OS in patients receiving later line ICI (HR 0.21, 90% CI 0.04-1.22). In the rare cancers cohort (n=90; 26 unique malignancies), IPS-High (17.8%) was associated with longer OS to ICI therapy (HR = 0.26, 90% CI 0.11-0.61), even when restricted to histologies represented in both IPS groups (HR = 0.18, 90%, CI 0.05-0.62). Conclusions Preliminary evidence suggests that IPS may serve as a generalizable, pan-cancer biomarker capable of stratifying outcomes for ICI treatment in populations traditionally excluded from immunotherapy benefit.

Adoptive T-cell therapy (ACT) has demonstrated marked clinical benefit in hematological malignancies but has limited efficacy against solid tumors. Cancer vaccines can improve ACT, but the mechanisms underlying this combination are poorly understood. Here, we combined ACT with chimpanzee adenovirus ChAdOx1 (ChAd) and modified vaccinia Ankara (MVA) encoding tumor antigens. Whereas PD1 blockade failed to improve ACT, the combination with ChAd/MVA vaccination drove durable regression of established tumors, correlating with expansion of tumor-reactive T cells in lymphoid organs and increased tumor infiltration by T cells. Mechanistically, ChAd priming induced CXCR3 ligands (CXCL10 and CXCL9) in the vaccine-draining lymph node, thereby recruiting transferred T cells to this node independently of cognate antigen. CXCR3 expression on the transferred T cells, but not on host cells, was required for the anti-tumor effect of the combination therapy and favored T-cell accumulation in the vaccine-draining lymph node and the tumor. These findings identify CXCR3 on the transferred T cells as a determinant of ACT plus vaccination synergy and provide a rationale for combining viral-vector vaccines with TCR-T therapies, and for selecting or engineering T cells to retain CXCR3 expression.

Purpose: A minority of patients with bladder cancer derive lasting benefit from immunotherapy, and current biomarkers capture only part of the biology. We evaluated whether tumor-cell MHC class II defines an immune state associated with outcome across disease stages and after PD-1/PD-L1 blockade. Experimental Design: We localized differential MHC-II activity to malignant epithelial cells by single-nucleus and single-cell RNA sequencing and confirmed HLA-DR expression by immunohistochemistry in 122 specimens. Chromatin profiling and IFN-{gamma} stimulation of cell lines and primary tumors supported derivation of an 11-gene tumor-cell program. Associations were tested in 434 patients with non-muscle-invasive disease, 82 receiving neoadjuvant pembrolizumab, and 288 receiving atezolizumab for metastatic disease. Results: Tumor-cell MHC-II was present in approximately one third of bladder cancers, and malignant cells accounted for the differential signal between MHC-II-high and MHC-II-low tumors. The program was inducible by IFN-{gamma} through JAK/STAT signaling. Within luminal non-muscle-invasive disease, MHC-II-low status was associated with progression (HR 3.31, 95% CI 1.37 to 7.99). In PURE-01, the 11-gene program was associated with pathological complete response (52% versus 24%, p = 0.018) and recurrence-free survival (p = 0.0054), retaining an independent association in models including tumor mutational burden and PD-L1. In bladder-primary metastatic disease, program-high status was associated with overall survival in unadjusted analysis (HR 0.62, 95% CI 0.44 to 0.89); the association did not extend to upper tract tumors (interaction p = 0.0018). Conclusions: Tumor-cell MHC-II defines an inducible state associated with outcomes across bladder cancer stages and after checkpoint blockade, supporting prospective evaluation by RNA and immunohistochemistry.

Background: While immunotherapies have transformed outcomes in several adult cancers, more than half of pediatric patients with high-risk neuroblastoma fail to achieve sustained responses, resulting in poor outcomes. Therefore, understanding the phenotypic and spatial organization of immune cells within the neuroblastoma tumor microenvironment is essential to identify mechanisms driving immunotherapy failure. Methods: To identify spatial determinants of the neuroblastoma immune landscape that may contribute to treatment failure, we dissected immunoregulatory mechanisms at single-cell and protein levels in neuroblastoma samples from 28 patients, using imaging mass cytometry (IMC, n=14) and high-dimensional spectral flow cytometry (n=18). Results: We characterized four distinct cellular neighborhoods, ranging from tumor-dominant to stromal and immune niches. Macrophages were broadly distributed across these niches. In contrast, T and B cells were largely confined to immune niches, forming immature tertiary lymphoid structure-like aggregates within the tumor and stromal cores. T cells displayed a CD69+ tissue-resident memory phenotype, with an overall reduced cytotoxic profile (in CD8+ T cells) and increased expression of inhibitory receptors (predominantly in CD4+ T cells), indicative of dysfunctional features. Intriguingly, T cell functional states differed between spatial niches, with a TCF7+/Ki-67+ self-renewing profile within immune niches, and increased granzyme B expression in CD8+ T cells in tumor cores. Interaction analysis pinpointed CD163+ macrophages as the dominant immunosuppressive interaction partner of T cells, particularly within the tumor edge and immune cores. Analysis of inhibitory ligand-receptor interactions identified the TIGIT/PVR/Nectin-2 axis as the main engaged axis between CD163+ macrophages and T cells. Nectin-2 expression on macrophages was particularly high within immune cores, and elevated in macrophages with direct T cell contact, suggesting a high probability of in situ engagement. Consistent with this immunosuppressive role, both CD163 and Nectin-2 expression on macrophages correlated with poor patient survival, substantiating the clinical relevance of inhibitory macrophage-T cell interactions. Conclusions: This study reveals T cell-excluded tumor niches and targetable inhibitory interactions between CD163+ macrophages and T cells. These insights provide a rationale for combinatorial immunotherapeutic strategies that both enhance T cell infiltration into tumor-rich areas and disrupt inhibitory signaling to improve immunotherapy efficacy in neuroblastoma.

The immunosuppressive tumor microenvironment (TME) poses formidable challenges for cancer immunotherapies. Among the complex TME landscape, the cytokine TGF-{beta}1 is an attractive soluble target for reinvigoration of anti-tumor immunity due to its pivotal function in immune cell suppression, extracellular matrix remodeling, and epithelial-to-mesenchymal transition (EMT) promotion, while immune checkpoint receptors exemplified by PD-1 and CD24 are promising surface targets. Though adaptive immune checkpoint inhibition is well established in clinical practice, TGF-{beta} blockade or innate immune checkpoint blockade is yet to be harnessed for tumor treatment. Here, leveraging CD24 overexpression on multiple tumor tissues and its unique recycling kinetics, we designed an innate Immune Checkpoint TArgeting Chimera (ICTAC) G01, a bifunctional CD24 antibody-TGF-{beta}1 receptor fusion protein that disrupts TGF-{beta}1 signaling by TGF-{beta}1 degradation instead of simple blockade and simultaneously inhibits the "don't eat me" CD24 signaling. We demonstrated that G01 effectively suppressed TGF-{beta}1-Smad signaling, reversed the EMT, and attenuated fibrotic collagen deposition. Additionally, it antagonized CD24 signaling to unleash robust antibody-dependent effector activity, further reprogramming the immunologically cold TME toward inflammatory phenotype. By selectively targeting malignant cells while sparing CD24-expressing B cells, G01 demonstrated a favorable safety profile. Notably, in patient-derived tumor fragments (PDTFs), G01 also inflamed the TME, underscoring its translational potential. Together, these results establish ICTAC as an effective strategy for tumor-specific receptor-mediated extracellular protein depletion, which supports its application for reversing TGF-{beta}1; and innate immune checkpoint-mediated tumor immunosuppression by concurrent targeting of both surface and soluble tumor-promoting factors.

Glioblastomas (GBMs) are uniformly fatal brain tumors resistant to immunotherapy, yet the mechanisms driving immune dysfunction remain poorly understood. Here we identify a tissue-specific mechanism of dendritic cell (DC) dysfunction contributing to GBM immune evasion. We demonstrate that while systemic immunity depends on type 1 conventional DCs (cDC1s), GBMs preferentially accumulate cDC2s with impaired antigen-presenting capacity. Further, microglia-derived GAS6 and PROS1 signaling through the AXL receptor on DCs suppresses DC activation and, critically, migration to tumor-draining lymph nodes. Pharmacologic AXL inhibition enhances DC migration and consequently anti-tumor immunity. Importantly, radiation therapy activates cDC1-mediated endogenous immune responses, which synergizes with mRNA vaccination to promote complete and durable immune-mediated tumor regression. These findings establish DC-mediated immunity as a therapeutic target in brain tumors and reveal a synergistic mechanism for combining radiation with personalized cancer vaccines.

Paediatric diffuse midline glioma (DMG) remains refractory to immunotherapy despite T-cell infiltration, indicating that local mechanisms actively suppress anti-tumour immunity. Using complementary genetic and orthotopic mouse models, we performed lineage-resolved profiling of the DMG immune microenvironment, resolving myeloid ontogeny and microglial states by distinguishing resident microglia from infiltrating bone marrow-derived macrophages. We identified microglia as the predominant tumour-associated myeloid population and discovered selective expansion of CD11c positive; microglia exhibiting enriched antigen-presentation and immune-regulatory transcriptional programs. Tumour-infiltrating CD4+; and CD8+; T cells exhibited chronic activation and exhaustion, while ligand receptor analysis predicted inhibitory microglia T cell communication. Pharmacological CSF1R inhibition depleted CD11c positive; microglia, attenuated antigen-presentation and immune-regulatory programs, and shifted tumour-infiltrating T cells toward a less exhausted phenotype. Together, these findings identify a previously unrecognised CD11 positive; microglia T-cell axis that establishes immune dysfunction in DMG and provide a rationale for combining myeloid- and T cell-targeted immunotherapies.

Glioma is a fatal tumor of the central nervous system (CNS) with limited therapeutic options. While immune checkpoint inhibitors (ICI) are gaining traction as a novel alternative treatment for human gliomas (HG), clinical trials have yielded mixed results. A proposed major barrier to ICI therapy in cancer is epithelial-mesenchymal plasticity (EMP)-driven intratumoral immunosuppression. However, studying this mechanism is difficult in ex vivo and murine models, which fail to adequately replicate cancer cell-immune cell interactions. Formalin-fixed, paraffin-embedded (FFPE) patient-derived canine glioma (CG) samples represent an attractive alternative approach. Although mechanistic perturbation is unachievable in archival FFPE tissues, CG is notoriously 'cold' immunologically and is actively being investigated as a comparative model of HG. Moreover, the immune microenvironment in CG advantageously develops under exposure to environmental conditions directly shared with humans. Yet, it remains unknown whether CGs harbor heterogeneous niches combining varied plastic phenotypes and immunosuppressive populations. Defining the immune landscape of CG in relation to EMP is therefore critical to determining its potential as a comparative model for immunotherapy response in HG. By combining standard histology, immunohistochemistry, and tissue microarray-based spatial transcriptomics, we analyzed 30 low-grade (LGr) and high-grade (HGr) FFPE CG cases (n=10 cases/subtype): astrocytomas (4xLGr, 6xHGr), oligodendrogliomas (1xLGr, 9xHGr), and undefined gliomas (3LxGr, 7xHGr). All CG subtypes harbored heterogeneous immunosuppressive niches associated with varied EMP phenotypes. Astrocytomas exhibited a more-mesenchymal identity correlated with recruitment of tumor-associated macrophages (TAMs). Oligodendrogliomas displayed a strong stem-like signature and uniquely upregulated a FOXP3/LAG3/SNAI1 triad, positioned directly at the interface of immunosuppression and EMP. Across all CG subtypes, a more-mesenchymal phenotype co-occurred with TAMs, and intratumoral T-cell dysfunction and exhaustion. We conclude that CG replicates the EMP-immunosuppression heterogeneity seen in humans. Importantly, our results emphasize the existence of subtype-specific mechanisms of EMP and immune evasion, underscoring the major relevance of subtyping for translational applications.

Although MSI-H/dMMR colorectal cancers and the rarer subset with pathogenic POLE exonuclease domain mutations can benefit from immune checkpoint blockade, MSS colorectal cancer remains largely refractory, raising the question of whether other DNA damage response defects may also confer sensitivity to immunotherapy. Here, we performed a systematic in vivo screen of recurrently altered DNA damage response (DDR) genes to determine whether distinct repair defects modulate response to PD-1 blockade in MSS colorectal cancer. Using a genome-edited murine model in immunocompetent mice, we found that DDR perturbations produced heterogeneous outcomes, indicating that the immunologic consequences of DNA repair deficiency may be pathway-specific. Loss of Brca1, Brca2, Atm, and Fanca enhanced response to anti-PD-1 therapy, whereas Atr and Msh6 deficiency were associated with poor benefit. Brca1/2-deficient tumors showed the strongest regressions, supporting a link between core homologous recombination deficiency and increased immune sensitivity. In an independent cohort of colorectal cancer patients treated with ICB from the MSK-IMPACT Clinical Sequencing Cohort, BRCA1 alterations were associated with improved survival status, while FANCA alterations showed a similar trend. Because ATM is therapeutically targetable, we evaluated pharmacologic ATM inhibition in MSS colorectal cancer. Sustained ATM inhibition induced immune-related transcriptional programs in vitro and, when administered as a pre-treatment in vivo, enhanced the antitumor activity of PD-1 blockade. Together, these findings suggest that selected DDR alterations may represent candidate biomarkers of immunotherapy sensitivity, while ATM inhibition may provide a rational combination strategy to enhance PD-1 blockade in MSS colorectal cancer.

Background: Immune checkpoint inhibitors (ICI) are efficacious in many solid tumors, but response in glioma is restricted to a small subgroup. The determinants of response and resistance to ICI remain poorly understood. Methods: Here we exploit a syngeneic hypermutated high-grade glioma model with dichotomous response to combined PD-1 and CTLA-4 inhibition to unravel determinants of tumor-infiltrating T-cells driving response. Tumor-infiltrating T-cells from ICI-responsive and non-responsive tumors were analyzed by single-cell RNA and T-cell receptor sequencing and tumor-reactive T-cell receptor clonotypes were functionally validated to characterize their transcriptional phenotypes. We verify our findings in IDH1 wildtype glioblastoma patients treated with neoadjuvant pembrolizumab. Results: ICI response was associated with intratumoral clonal expansion of tumor-reactive cytotoxic T-cells and increased infiltration of CXCR6+ CD4+ tissue resident memory T-cells (Trm). CD4 stem-like memory T-cells in responding tumors demonstrated elevated interferon responses, following trajectories toward clonally expanded Trm, versus trajectories toward exhaustion in non-responsive tumors. In responsive tumors, CD4+ Trm interacted with infiltrating CXCR3+ tumor-reactive and clonally expanded, yet transcriptionally versatile cytotoxic T-cells. Probing the post neoadjuvant ICI high-grade glioma patient tissue dataset, we confirmed increased CXCR6 expression in CD4+ T cells and the association of CD4+ Trm with prolonged overall survival. Conclusion: These findings identify CD4 tissue-resident memory T-cells as determinants of ICI response in IDH1 wildtype high-grade glioma and warrant their further investigation to improve immunotherapy outcomes.

Purpose: Existing prognostic models for brain metastases from lung cancer rely on clinical variables and do not capture the biological heterogeneity of host or tumor factors underlying survival outcomes. We evaluated whether MRI-derived radiomic biomarkers improve prognostic stratification beyond clinical variables. We also investigated their biological correlates using matched histopathology. Experimental Design: This retrospective study included 103 patients with brain metastases from lung cancer and matched pre-operative MRI and histopathology. Radiomic features from T1-weighted contrast-enhanced and T2-weighted fluid-attenuated inversion recovery sequences were combined with clinical variables to train Cox proportional hazards, random survival forest, and DeepSurv models for overall survival (OS), CNS progression, and leptomeningeal (LM) progression. Risk groups from an imaging-only model were compared for clinical and histopathologic differences. Results: Imaging features improved prognostic performance beyond clinical variables across all modeling frameworks, with the combined clinical-imaging DeepSurv model achieving the highest concordance index for OS (0.728). Risk groups from the best-performing model for each endpoint differed significantly in OS (median 26.7 vs. 9.1 months, p < 0.001) and LM progression (p = 0.003), but not in CNS progression. Imaging-only risk groups did not differ significantly in any clinical variable, but high-risk patients were less likely to have tumor-infiltrating lymphocytes (46% vs. 77%, p = 0.010) and PD-L1 expression [&ge;] 50% (10% vs. 32%, p = 0.049). Conclusions: MRI radiomic biomarkers provide prognostic information beyond established clinical variables in lung cancer brain metastases and correspond to features of the tumor immune microenvironment, supporting their potential to refine risk stratification.

Introduction: Perioperative systemic therapy improves outcomes in gastroesophageal adenocarcinoma, but many patients do not receive postoperative treatment. We examined whether host characteristics and perioperative inflammatory and albumin changes provided information about adjuvant initiation beyond tumour pathology, and whether initiation was associated with survival and disease control. Method: This retrospective cohort included patients undergoing curative-intent resection for gastroesophageal adenocarcinoma at the McGill University Health Centre between 2006 and 2025. Sequential logistic models evaluated pathological characteristics, pre-treatment host variables and perioperative changes in CBC-derived neutrophil-to-lymphocyte ratio (cNLR) and albumin. Postoperative measurements preceded adjuvant initiation. Nested comparisons used matched complete cases. Day-90 landmark and time-varying Cox models assessed associations between adjuvant initiation and survival. Results: Among 243 patients, 78 (32.1%) did not initiate adjuvant therapy. Adding host variables improved apparent discrimination for initiation beyond pathology (AUC 0.672 to 0.763; P=0.002). Greater perioperative cNLR increase was associated with lower odds of initiation (adjusted OR 0.67 per unit increase in {Delta}log2; cNLR, 95% CI 0.47-0.95), whereas more favourable albumin change was associated with higher odds (OR 1.07 per g/L, 95% CI 1.01-1.13). Neither marker retained a clear independent association when modelled together. Adjuvant initiation by day 90 was associated with longer overall survival (adjusted HR 0.53, 95% CI 0.36-0.78) and disease-free survival (HR 0.57, 95% CI 0.39-0.84), with similar time-varying findings. Conclusion: Host inflammatory and albumin changes added information about adjuvant initiation beyond tumour pathology, and initiation was associated with longer survival. Prospective evaluation should determine whether host-directed perioperative strategies can improve postoperative treatment delivery.

Tumor-associated macrophages (TAMs) contribute to tumor immune evasion and therapeutic resistance. However, the epigenetic and transcriptional regulators that control TAM function remain largely unidentified. Here we investigated the role of the SWI/SNF chromatin remodeling complex in TAMs and whether disruption of SWI/SNF function in TAMs could improve immunotherapy. Pharmacologic inhibition of SWI/SNF ATPase activity improved the efficacy of checkpoint blockade immunotherapy, slowing tumor growth and reprogramming transcription broadly in tumor cells, tumor-infiltrating lymphocytes, and TAMs. To define the role of SWI/SNF in TAMs specifically, we genetically deleted the SWI/SNF subunit Arid1a in myeloid cells and found this was sufficient to suppress tumor progression and enhance checkpoint blockade response. Epigenomic and single cell analyses indicated that SWI/SNF inhibition and ARID1A deletion in TAMs reduced accessibility at enhancers of genes associated with poor prognosis, such as Spp1, and increased accessibility at promoters of interferon-stimulated genes (ISGs). CD86 was elevated on ARID1A-deficient TAMs and the enhanced immunotherapy response required CD86 costimulation and CD8+ T cells. These findings establish ARID1A-dependent chromatin remodeling as a determinant of TAM gene expression programs and show that disruption of myeloid SWI/SNF function improves checkpoint blockade immunotherapy via TAM reprogramming.

The immunomodulatory effects of chemotherapy (chemoimmunomodulation; CIM) are clinically consequential and heterogeneous, yet no systematic framework exists for classifying the immunomodulatory trajectory a tumor follows in response to treatment (CIM trajectory). Here, we present the CIM Induction Classifier (CIMIC), an unsupervised clustering pipeline leveraging delta gene expression across 3,189 CIM-related genes to classify specimens chemoimmunomodulatory trajectory. Applied to two pre- and post-chemotherapy breast cancer (BC) datasets (NKI/SMC, N = 36; NEO, N = 19) and nine epirubicin-perturbed triple-negative BC (TNBC) cell lines, CIMIC identified two divergent CIM trajectories: a functional CIM (Fun-CIM) trajectory, broadly conserved across tumors and cell lines and characterized by induction of inflammatory cell death, antigen presentation, viral mimicry, and adaptive immune activation programs, and a dysfunctional CIM (Dys-CIM) trajectory, characterized by induction of proteostatic and metabolic stress-adaptation programs, reduced immune cell abundances and cytotoxic activity, and enrichment of aggressive BC subtypes. Using survival and longitudinal transcriptomic data in NKI/SMC (N = 20), treatment-induced increases in Fun-CIM-associated genes and ssGSEA scores were associated with reduced recurrence, whereas Dys-CIM-associated genes and scores were associated with increased recurrence. In multivariable analyses within independent chemotherapy-treated BC cohorts (METABRIC, N = 412; SCAN-B, N = 2,462), higher baseline Fun-CIM ssGSEA scores were associated with better outcomes, whereas higher baseline Dys-CIM ssGSEA scores were associated with worse outcomes. These findings establish CIM as a dynamic, trajectory-level process and position CIMIC as a framework for defining CIM trajectories and supporting future efforts to identify predictors, mechanisms, and therapeutic strategies that maximize beneficial CIM.

The current treatment regimen for neuroblastoma involves immunotherapy, including a monoclonal antibody that recognizes disialoganglioside (GD2), expressed at high levels on neuroblastoma. GD2 is not present on most normal tissues except for nerves. Thus, anti-GD2 antibody treatment causes substantial, dose-limiting neuropathic pain. B7-H3 is overexpressed on multiple tumor types, including neuroblastoma, and is largely absent on nerves and other normal tissues. We designed a bispecific antibody (bsAb) that requires simultaneous binding of these two tumor antigens to achieve tight binding of tumor cells. Our preclinical research shows that, compared with a monospecific anti-GD2 antibody, the GD2xB7-H3 bsAb has improved tumor specificity, comparable antitumor efficacy, and reduced nerve binding and pain-associated toxicity. Since this bsAb does not bind to nerves, it may permit more tolerable and sustained treatment schedules than are currently feasible with monospecific anti-GD2 antibodies. In addition, its enhanced tumor specificity may support future development as a targeted delivery platform for antibody-drug conjugates or other payload-based therapies, potentially improving both efficacy and quality of life for patients with neuroblastoma.

Whether human tumor-specific CD4 T cells can drive antitumor immunity in cancers lacking tumor-cell MHC class II expression has not been established. In MHC class II-negative melanoma and breast cancer, CD4 T cells with a transcriptional signature of tumor specificity correlated with myeloid and CD8 T cell activation. Using a patient-derived NY-ESO-specific, HLA-DP04-restricted TCR, we tested whether human CD4 T cells could control tumors through indirect antigen presentation. In vitro, CD4 T cells inhibited HLA-DP-negative melanoma growth through recognition of tumor-derived antigen on antigen presenting cells (APC). In humanized mice, CD4 T cell transfer induced regression of HLA-DP-negative tumors, and control required HLA-matched human APCs. CD4 T cell transfer induced endogenous CD8 T cell proliferation and myeloid activation that mirrored immune programs correlated with the presence of these cells in patients. These findings establish that human tumor-specific CD4 T cells coordinate antitumor immunity through APC without direct tumor recognition, supporting their therapeutic relevance in MHC class II-negative cancers.

Medulloblastoma is the leading type of malignant brain tumor in children. Despite recent advances in T cell-based immunotherapy, the low mutational burden of medulloblastoma poses a considerable challenge to the discovery of mutation-derived neoantigens. Previous studies of medulloblastoma have investigated tumor-associated antigens and neoantigens derived from aberrant splice junctions. The landscape of non-canonical HLA class I-bound peptides (ncHLAp) remains poorly defined. To broaden the repertoire of targetable antigens in medulloblastoma, we mapped the ncHLAp landscape across the four major molecular subgroups of medulloblastoma (Group 3, Group 4, WNT, and SHH) by integrating immunopeptidomic and transcriptomic analyses. Candidates were further filtered against normal-tissue immunopeptidomic and ribosome profiling datasets to identify cancer-restricted ncHLAp (CR ncHLAp). A total of 2,298 ncHLAp were identified across 21 human medulloblastoma samples, of which 598 were CR ncHLAp. These CR ncHLAp were primarily derived from non-canonical translational sources, including retained introns, out-of-frame open reading frames, and long non-coding RNAs. Some CR ncHLAp were shared across medulloblastoma samples and detected in other cancer types. More than 70% of the CR ncHLAp were predicted to bind at least one patient-matched HLA allotype, and approximately 87% were predicted to have immunogenic potential. Collectively, this study defines a previously undercharacterized component, CR ncHLAp, of the medulloblastoma HLA-I ligandome and suggests that CR ncHLAp may serve as promising candidate targets for T-cell-based immunotherapy in medulloblastoma.

Background Colorectal cancer (CRC) remains a leading cause of cancer-related mortality, and emerging T cell engager (TCE) immunotherapies require predictive preclinical models that capture patient-specific tumour biology and tumour-immune interactions. Although patient-derived organoid (PDO)-immune co-culture systems show promise for evaluating immunotherapy responses, many rely on matrix-embedded cultures that limit scalability and reproducibility. We therefore developed and validated a low-matrix organoid-T cell co-culture platform for functional assessment of TCE activity in patient-derived CRC models. Methods Patient-derived CRC organoids representing diverse molecular and genetic backgrounds were co-cultured with activated allogeneic CD3+ T cells in a suspension low-matrix format. Matrix concentration, medium composition, T cell activation status, and assay duration were optimized. Tumour killing, T cells activation, cytokine secretion, apoptosis, and motility were assessed using flow cytometry, live-cell imaging, cytokine profiling, and immunofluorescence. The platform was evaluated using EGFR- and HER2-targeting bispecific T cell engagers across 21 CRC organoid models and multiple healthy donor-derived T cell populations. Results Optimization identified 1% matrix and a 1:1 organoid: T cell medium that preserved organoid integrity while maintaining T cell viability, activation, and motility. The final workflow enabled reproducible co-culture of 5-day mature organoids with 7-day activated T cells for 72 hours. EGFR-targeting TCEs induced tumour killing, T cell activation, and IFN-{gamma} secretion across donor-organoid combinations. Screening of 21 CRC organoid models revealed substantial inter-patient heterogeneity, with 12 models maintaining [&ge;]50% baseline viability and supporting functional TCE evaluation. EGFR- and HER2-targeting TCEs produced potent dose-dependent cytotoxicity, with IC50 values ranging from 0.0188 to 54.77 nM across responsive models and up to 75%-85% tumour killing in the most sensitive organoids. These responses were accompanied by increased effector cytokine secretion. Real-time imaging confirmed dynamic T cell engagement and apoptosis-driven organoid destruction following TCE treatment. Conclusions We establish a robust, scalable, human-relevant low-matrix organoid-T cell co-culture platform for functional screening of T cell engagers in patient-derived CRC models. By enabling integrated assessment of tumour killing, immune activation, cytokine responses, and tumour-immune interactions while preserving inter-patient heterogeneity, this system provides a translational framework for immunotherapy development. The platform may support candidate prioritisation, biomarker discovery, patient stratification, and preclinical evaluation of immune-engaging therapeutics.