Cancer Immunology Research

Immune mobilizing monoclonal TCR against cancer (ImmTAC) are cancer therapeutics that activate T cells through recognition of a tumor-associated antigenic MHC/peptide complex. A first-in-class ImmTAC, Tebentafusp, is approved for the treatment of metastatic uveal melanoma. While clinical efficacy is thus established, the cellular mechanisms underpinning ImmTAC action are not fully resolved. Using a recently established experimental strategy to generate suppressed human primary cytotoxic T lymphocytes (CTL), we have investigated an ImmTAC that recognizes a peptide derived from the tumor associated antigen NY-ESO-1 in comparison to direct engagement of a TCR recognizing the same MHC/peptide complex. In response to endogenous antigen presentation, ImmTACs could elicit tumor cell cytolysis by suppressed CTL, but not IFN{gamma} secretion, in a manner dependent on the engager affinity for CD3{varepsilon}. ImmTACs enhanced the efficient execution of subcellular CTL polarization steps required for effective cytolysis and could trigger calcium signaling. These data establish that ImmTACs activate CTL similarly to direct engagement of a TCR by MHC/peptide and are likely to retain this capability under suppressive conditions such as in the tumor microenvironment.

Given the critical role of CD4 T cells in anti-tumor immunity, strategies to harness these cells for cancer immunotherapy are gaining increasing interest. Historically overshadowed by CD8 T cells, cytotoxic CD4 T cells can directly kill MHC class II-expressing tumor cells. However, the defining molecular signature and the mechanisms underlying their cytolytic activity remain poorly understood, particularly in cancer patients. Here, using ex vivo single-cell transcriptomic and spatial analyses of CD4 T cells from paired blood and tumor samples of melanoma patients, we identified Killer Cell Lectin-Like Receptor G1 (KLRG1) as a defining surface marker of cytotoxic CD4 T cells. The CD4+ KLRG1+ T cell subset was notably enriched among circulating cells compared with tumor-infiltrating populations, which were instead enriched in T follicular helper (Tfh) states. Functionally, KLRG1+ CD4 T cells expressed elevated levels of cytotoxic genes and exhibited superior tumor-killing capacity compared with their KLRG1- counterparts. We demonstrated that their cytotoxicity is granulysin-dependent, as confirmed by CRISPR/Cas9-mediated gene deletion. Mechanistically, CD4 T cells spared MHC class II+ cells lacking the KLRG1 ligands CD324 and CD325, such as professional antigen-presenting cells (APCs), indicating that cytotoxicity was selectively directed towards tumor cells while preserving immune cells. Finally, by investigating how the tumor microenvironment may impair CD4 T cell cytotoxicity, we showed that tumor-derived factors, including interleukin-6 (IL-6), are key drivers promoting the transition of cytotoxic CD4 T cells toward a Tfh phenotype. In summary, our findings define KLRG1 as a defining cell surface marker of cytotoxic CD4 T cells in cancer patients, as well as a key regulator that protects MHC class II+ APCs. Moreover, targeting the IL-6 signalling pathway may enhance CD4 T cell anti-tumor cytotoxicity, offering new avenues for cancer immunotherapy.

Abstract/SummaryImmune checkpoint blockade can produce long-lasting responses in patients with metastatic melanoma; notably, combined CTLA-4/PD-1 blockade has been associated with approximately 52% melanoma specific 10-year survival (1). Yet, nearly half of patients experience minimal clinical benefit, and intensified regimens come with substantial risk of severe immune-related toxicity. The precise determinants of immunotherapy response are incompletely defined, reflecting a complex interplay between tumor biology and host immunity. This is especially consequential for patients whose disease progresses on checkpoint blockade, for whom effective salvage options are limited. In a series of patients with NRAS-mutated melanoma refractory to checkpoint inhibitors, we found that intratumoral administration of talimogene laherparepvec (T-VEC) combined with MEK inhibitor binimetinib induced exceptional clinical responses by amplification of pre-existing T cell responses and induction of de novo tumor-reactive immunity.

Adoptive cell therapy (ACT) of tumor-specific T cells can improve survival in a subset of cancer patients. Current ACT approaches may be limited by using highly differentiated T cells which can be inhibited by an immunosuppressive tumor microenvironment (TME). Here, we developed an approach to optimize ACT and used spatial transcriptomics to show how stem-like and effector CD8+ T cells differentially mediate tumor control following vaccination. Spatial transcriptomic profiling of the TME showed that ACT with stem-like T cells followed by intravenous vaccination prevented immune exclusion, increased infiltration of pro-inflammatory macrophages, and reprogrammed tumor cells to upregulate Type I and Type II IFN signaling and apoptotic gene programs. The protective transcriptomic signature of the TME in this ACT model contained overlapping biomarkers with patients who responded to ACT therapy. This approach demonstrates synergy between transferred stem-like T cells and intravenous vaccination to transcriptionally remodel the TME and enhance tumor control.

Interleukin-2 (IL-2) remains an attractive cytokine for enhancing antigen-specific CD8 T cell responses in cancer immunotherapy, but systemic toxicity hinders its broad clinical application. To address this, various IL-2-based therapeutics have been engineered with altered IL-2 receptor bias or targeted delivery to tumors, the tumor microenvironment, or immune cell populations. Ideally, IL-2 signals should be selectively delivered to antigen-specific CD8 T cells, boosting their responses and promoting effector differentiation while sparing non-targeted populations. Immuno-STATTM (Selective Targeting and Alteration of T cells) is a fusion protein platform comprising a bivalent peptide-MHC class I complex and an affinity-attenuated IL-2 mutein that co-stimulates TCR and IL-2 signaling in epitope-specific CD8 T cells. Here, we investigated whether a DbGP33-41-targeted Immuno-STAT enhances DbGP33-specific CD8 T cell responses in a mouse model of chronic lymphocytic choriomeningitis virus (LCMV) infection. Immuno-STAT treatment selectively expanded DbGP33-specific CD8 T cells with an effector-like phenotype. Non-targeted DbGP276-specific CD8 T cells showed little to no expansion in response to DbGP33-41-targeted Immuno-STAT therapy, underscoring the selectivity of this approach. However, minor changes in phenotypic markers, including increased expression of CD25 and CX3CR1, were observed in non-targeted CD8 T cells, likely reflecting bystander IL-2 signaling. Combining Immuno-STAT with PD-1 blockade augmented DbGP33-specific CD8 T cell responses more effectively than PD-1 blockade alone, with minor effects on the non-targeted DbGP276-specific population. These findings inform the clinical development of Immuno-STAT and other IL-2 therapeutics and highlight the value of coordinated TCR and IL-2 stimulation during chronic antigen exposure, alone or in combination with PD-1 blockade. IMPORTANCEInterleukin-2 (IL-2) is a key cytokine for promoting effector differentiation of antigen-specific CD8 T cells and remains an attractive agent in cancer immunotherapy, but systemic toxicity limits its clinical use. This study addresses a central challenge in IL-2-based immunotherapy: delivering IL-2 to cognate antigen-specific CD8 T cells while minimizing activation of non-targeted populations. Using a mouse model of chronic lymphocytic choriomeningitis virus (LCMV) infection, we show that the Immuno-STAT (Selective Targeting and Alteration of T cells) platform selectively expands targeted virus-specific CD8 T cells and enhances their function while limiting effects on non-targeted populations. We also show that combining Immuno-STAT with PD-1 blockade further enhances targeted virus-specific CD8 T cell responses during chronic LCMV infection. These findings provide mechanistic and preclinical support for integrating T cell receptor (TCR) specificity with IL-2 signaling to advance cancer immunotherapy and guide next-generation IL-2 therapeutics for cancer and chronic infection.

Immune checkpoint inhibition (ICI) is clinically active against multiple cancers, including urothelial cancer at the non-muscle invasive, muscle-invasive, and metastatic stages. Despite this, large numbers of patients experience disease progression and relapse after treatment with ICI-containing regimens. Tumor antigen-specific T cells are critical to ICI response, however few studies have evaluated the breadth and magnitude of tumor antigen-specific T cell responses with ICI therapy. In this study, we mapped the tumor antigen immunodominance hierarchy in the BBN963 model of murine basal-like bladder cancer for endogenous tumor neoantigens expressed physiologically. We used a high-throughput matrixed ELISpot assay to detect CD8+ T cell responses to predicted BBN963 tumor antigens derived from multiple mutational genomic sources. We found CD8+ T cell responses were directed against a subset of tumor antigens forming a stable and reproducible immunodominance hierarchy across individual mice. Treatment with anti-PD-1 or anti-CTLA-4 did not substantially reshape this hierarchy or broadly shift dominant responses to previously defined subdominant epitopes. Predicted peptide MHC binding stability and affinity was associated with antigen immunogenicity. Cancer-testis antigens, endogenous retroviral antigens, and SNV-derived tumor antigens that were immunogenic were found across tumor subclones. By diversifying the immunogenic antigen repertoire beyond SNVs, we achieved nearly 100% tumor subclone coverage, suggesting that broader antigen selection could help immunotherapy target more tumor subclones. In conclusion, this study supports the stability of the immunodominance hierarchy under ICI therapy and a role for broadening antigen discovery to multiple expressional sources in immunotherapy design.

CAR-T cell therapy has shown limited efficacy in solid tumors, largely due to T cell dysfunction driven by chronic antigen exposure. To uncover mediators of this dysfunction, we developed an in vivo screening platform using an ovarian xenograft tumor model in which CD28-based CAR-T cells undergo exhaustion leading to tumor escape. Transcriptomic profiling of tumor-infiltrating CAR-T cells at different stages revealed dynamic upregulation of exhaustion-associated genes. We used this data to design a focused CRISPR/Cas9 library and performed an in vivo screen. We identified 14 significantly enriched candidate genes, among which ZC3H12C emerged as the top hit. Single-cell RNA and ATAC-seq confirmed ZC3H12C expression in CAR-T cells undergoing early exhaustion in vivo. ZC3H12C disruption enhanced CAR-T cell persistence and antitumor efficacy while reducing exhaustion, across both CD28- and 4-1BB-based CARs targeting distinct antigens. These results highlight ZC3H12C as a promising target to improve CAR-T therapy in solid tumors.

CD47 is a "dont eat me" signal that suppresses macrophage-mediated phagocytosis. Its upregulation in lung and other cancers facilitates tumour immune escape, making CD47 a promising immunotherapeutic target. Studies have demonstrated anti-tumour efficacy of CD47 blockade in preclinical lung cancer models, but monoclonal antibodies targeting CD47 have had limited efficacy as monotherapy in solid tumour patients to date. This discrepancy may in part reflect the use of human tumour xenografts in mice that do not have fully-functioning immune systems in preclinical efficacy studies. Thus, understanding tumour responses to CD47 inhibition using immune competent lung cancer models is needed to inform strategies to harness its therapeutic potential. Here, we characterized the effects of CD47 knockout (KO) on tumour growth and immune responses in two syngeneic, orthotopic murine lung cancer models, LLC-Luc (LLC) and CMT167 (CMT). As expected, CD47 KO impaired the fitness of LLC and CMT cells in vivo. Mice with CD47-deficient tumours exhibited prolonged survival and increased infiltration of anti-tumour leukocytes. However, although CD47 KO impaired lung tumour growth in syngeneic mice, KO tumours were ultimately lethal. Immunophenotyping revealed an increased prevalence of PD-L1+ cells in CD47-deficient tumours, nominating PD-L1-mediated suppression of tumour immunity as an acquired mechanism of resistance to CD47 blockade. Concordantly, dual inhibition of CD47 and PD-L1 extended the survival of CMT tumour-bearing mice compared to inhibition of either alone. These findings suggest that PD-L1 blockade could be leveraged to overcome resistance and potentiate the efficacy of CD47-targeted immunotherapy in lung cancer.

CAR-T immunotherapy has achieved remarkable efficacy in hematologic malignancies. However, the widespread clinical adoption of autologous CAR-T products remains constrained by high costs, lengthy manufacturing process, and limited accessibility. Universal or off the shelf CAR-T (UCAR-T) cells derived from healthy donors offer a promising alternative, enabling immediate treatment at a lower cost. However, the allogeneic nature of UCAR-T cells triggers immune rejection by the host immune system after infusion, thereby compromising their persistence and therapeutic efficacy. Current strategies to circumvent this rejection focus on disrupting HLA class I expression. Although this modification allows UCAR-T cells to successfully evade T cell mediated elimination, the loss of HLA class I molecules renders them vulnerable to attack by host natural killer (NK) cells. In contrast to previous approaches that attempt to retain certain non-classical HLA molecules (such as HLA-E or HLA-G) to inhibit NK cells, we directly focused on editing the ligands that mediate NK cell rejection. Through transcriptomic and in vitro validation analyses, we found that UL16 binding proteins (ULBP) 2/5/6 were substantially upregulated in UCAR-T cells compared with nontransduced donor T cells. Elevated ULBP expression effectively activates the NKG2D receptor on allogeneic NK cells and leads to killing of UCAR-T cells, thereby impairing UCAR-T function. To test whether abrogating this NK activating signal could improve UCAR-T persistence and antitumor efficacy, we generated ULBP knockout UCAR-T cells using CRISPR-Cas9 editing. Deletion of ULBP2/5/6 significantly reduced NK cell mediated killing in vitro without affecting CAR expression or T cell effector function. Compared with wild type UCAR-T cells, ULBP deficient UCAR-T cells exhibited enhanced tumor killing efficacy in the presence of NK cells. Collectively, our findings identify ULBP upregulation as one of the mechanisms underlying NK cell mediated rejection of HLA deficient UCAR-T cells. Targeted ablation of ULBP molecules provides a novel strategy to confer resistance to host NK cells, thereby improving the therapeutic potential of universal CAR T products.

Defining the genetic and cellular programs that allow solid tumours to evade immune control requires preclinical models that preserve the complexity of the human tumour immune microenvironment. Most available systems capture only part of this biology. Organoid cultures and ex vivo tumour fragments can retain patient-derived tumour architecture and associated immune cells, but immune populations are typically maintained only for short periods. These models also cannot capture antitumour immune responses in the physiological setting of a living organism. Patient-derived xenografts propagated in humanized mice offer a potential path to overcome these limitations by combining patient-derived tumour tissue with a reconstituted human immune system. However, few studies have systematically tested whether these models reproduce the diverse immune cell phenotypes present in the parental tumours from which they are derived. This has limited their use for studying tumour-intrinsic mechanisms that shape immune composition and promote immune evasion. To address this gap, we profiled tumour-infiltrating, splenic, and bone marrow immune cells from ovarian, head and neck, and renal PDX models propagated in CD34+ hematopoietic stem cell (HSC)-derived huNOG-EXL mice expressing human IL-3 and GM-CSF. By comparing tumours grown across distinct HSC donor backgrounds with their matched primary tumour samples, we found that tumour-intrinsic factors are a dominant determinant of immune composition in humanized PDX tumours. Across models, these immune infiltrates generally resembled those of the corresponding parental tumours. These findings support humanized PDX models as a platform for functionally interrogating tumour-intrinsic drivers of immune composition and immune evasion in solid tumours.

Myeloid derived suppressor cells (MDSCs) are key players in the immune-suppressed tumor microenvironment (TME) and significantly contribute to immune checkpoint inhibition (ICI) resistance, making them favorable targets for cancer immunotherapy. Epigenetic reprogramming of MDSCs using histone deacetylase (HDAC) inhibitors shows promise to sensitize the TME to ICIs. However, the molecular mechanism of HDAC inhibition in MDSCs has yet to be elucidated. Murine and human MDSC models treated with Entinostat revealed that the long non-coding RNA Malat1 downregulates pSTAT3 and decreases MDSC-mediated suppression of T cell proliferation. Through HDAC inhibitor screens, we identified HDAC1 as preferentially regulating Malat1 expression, STAT3 activation, and MDSC suppression. We also show that HDAC1 inhibition increases MDSC apoptosis by shifting pro-vs. anti-apoptotic signals and increases G0/G1 cell cycle arrest via decreasing G1-S transition cyclin-CDK complexes. Collectively, our findings provide a multi-pronged mechanism of HDAC inhibition in MDSCs that inform the development of future rational combination therapies. One Sentence SummaryHDAC1 inhibition in MDSCs increases Malat1, decreases pSTAT3, induces apoptosis/cell cycle arrest, and decreases suppression of T cells

Targeting immunosuppressive tumor-associated myeloid populations has emerged as a promising strategy to enhance anti-tumor immunity. The CCL2-CCR2 axis plays a central role in the recruitment of monocytes that differentiate into tumor-associated macrophages (TAMs), yet the therapeutic potential of CCR2 targeting remains limited. Using transgenic CCR2-DTR mice, we show that depletion of CCR2+ monocytes and TAMs reduced tumor growth across multiple models, accompanied by remodeling of the tumor microenvironment (TME). Residual CCR2-independent TAMs exhibited a pro-inflammatory and less immunosuppressive phenotype, and expressed the alternative recruitment receptor CCR3. Concomitantly, CCR2 depletion markedly enhanced anti-tumor immunity by increasing infiltration of activated CD8+ T cells. Splenocytes from tumor-bearing CCR2-DTR mice showed an increased IFN{gamma} response to a cancer-associated antigen. Furthermore, CCR2 depletion synergized with immune checkpoint blockade to enhance tumor control. Despite these effects, compensatory tumor infiltration of neutrophils following CCR2 targeting limited therapeutic benefit. These neutrophils exhibited a terminally differentiated, immunosuppressive phenotype and were associated with increased cancer cell-intrinsic expression of the neutrophil-recruiting chemokines Cxcl2 and Cxcl5. Importantly, combined depletion of CCR2+ cells and neutrophils overcame this resistance mechanism, resulting in reduced tumor growth, prolonged survival, and complete tumor clearance in 25% of the mice. Dual depletion of CCR2+ cells and neutrophils was also associated with a synergistic increase in circulating CD8+ T cells. These findings highlight the dynamic remodeling of the TME upon CCR2 depletion and suggest that combinatorial strategies addressing immunosuppressive neutrophil infiltration may improve the efficacy of CCR2 targeting therapies.

BackgroundTumour-associated macrophages (TAMs) play critical roles within the tumour microenvironment regulating immune evasion and therapeutic response. Previously, we have shown that the combination of Checkpoint kinase 1 inhibitor (CHK1i) with a subclinical dose of hydroxyurea (LDHU) reprograms the tumour immune microenvironment to a pro-inflammatory status. MethodsWe investigated a tumour-restricted Fcgr4 (Cd16.2) expressing macrophage population in multiple murine tumour models and the impact of CHK1i+LDHU on this population, using conventional and imaging flow cytometry as well as single-cell sequencing. ResultsTranscriptional profiling using CITE-seq and single-cell RNA sequencing reveals that Fcgr4 TAMs closely resemble Fcgr4- TAMs but display modest enrichment of interferon-associated and inflammatory gene programs, consistent with a functionally biased state rather than a distinct lineage. Importantly, we show that a highly tumour selective CHK1i+LDHU therapy shifts TAMs toward a more inflammatory phenotype while preserving dominant immunosuppressive features. Depletion of CSF1R macrophages enhanced CD8 T cell activation without influencing tumour growth but significantly augmented therapeutic efficacy of CHK1i+LDHU. ConclusionTogether, these findings define a novel TAM population and establish how targeted therapy reshapes, but does not fully overcome, TAM-mediated immune regulation.

BRAF-targeted therapy (BRAFi/MEKi) and immune checkpoint blockade (anti-PD-1/anti-CTLA-4) have transformed the treatment of BRAF-mutant metastatic melanoma. While most patients who respond to targeted therapy eventually progress, a subset derives durable benefit, and biomarkers to identify this subset would inform optimal treatment selection. In this study, we analyzed pre-treatment tumor samples from a clinically annotated cohort of 155 patients with BRAF-mutant metastatic melanoma treated with first-line BRAFi/MEKi and followed for up to five years. We stratified patients into durable responders (PFS [&ge;] 24 months) and rapid progressors (PFS < 6 months with progression) and found that a global metric of tumor genomic heterogeneity, rather than individual gene alterations, distinguished these groups. Combining genomic heterogeneity with baseline tumor burden (e.g., lactate dehydrogenase (LDH) or radiographic lesion dimensions), we developed a parsimonious model that predicted durable responders with high precision and specificity. Notably, the analogous population of patients treated instead with immunotherapy were not durable responders, suggesting that the selected predictors of durable responders are targeted therapy specific. Spatial profiling of a subset of pre-treatment biopsies (n = 47) demonstrated that high intratumoral, but not peritumoral, CD8+ T-cell infiltration correlated with prolonged survival on BRAF-targeted therapy and served as an independent predictive factor when considered with genomic heterogeneity and features of clinical tumor burden. Together, these findings highlight the distinct baseline intrinsic and extrinsic features underlying durable response to BRAF-targeted therapy and support their potential implication in guiding treatment selection for patients with BRAF-mutant metastatic melanoma. One-Sentence SummaryIntegrated clinical, tumor genomic, and immune microenvironmental features predict durable responses to BRAF-targeted therapy.

Peritoneal metastases (PM) are the leading cause of cancer-related death in gastric cancer (GC) patients with survival typically < 9 months. Here, we demonstrate that TIM3 and its ligands are increased along the GC continuum and associated with poor survival. Integrated omics analyses and functional studies revealed highly enriched TIM3 in CD163+ tumor associated M2 immunosuppressive macrophages significantly promote tumor cell invasion and tumor growth in vivo, while TIM3 depletion in macrophages reduced tumor cell malignant attributes and increased T cell immunity from PBMCs or CD45+ immune cells of malignant ascites in co-culture system. By cytokine and kinase arrays, we discovered that depletion of TIM3 in macrophages reduced the production of notable secretome of cytokines/chemokines from M2 macrophages; and the protumor function of TIM3+ macrophages rely on the p90RSK1/2/CCL20 axis. Finally, we reveal that TIM3 blockage or genetic KO had superior antitumor activity in combination with anti-PD1 immunotherapy and mitomycin C (MMC) chemotherapy. Together, this study uncovers an important role for TIM3 in tumor associated M2 macrophages and underscores the potential of TIM3 blockage in GC patients with PM. Statement of significanceIn this study, we show TIM3 increases along GC continuum, and highly enriched on tumor associated M2 macrophages that fuel tumor growth; and suppress T cell function via p90RSK1/2/CCL20 axis. TIM3 depletion restores T-cell immunity and curbs tumor growth. TIM3 blockade combined with anti-PD1 and mitomycin C provide a novel therapeutic strategy for GC patients with PM.

Irreversible electroporation (IRE) has shown promise for treating pancreatic ductal adenocarcinoma (PDAC), but whether IRE can induce an abscopal effect is not established. We demonstrated that the combination of IRE and anti-PD-1 antibody could trigger robust abscopal effects in preclinical models of metastatic PDAC. Data from multiple in vivo models, RNA-seq, scRNA-seq, and spatial immunofluorescence provide compelling evidence that IRE induced mitochondrial dysfunction and cellular stress, which triggered activation of the cGAS-STING pathway and subsequent systemic antitumor effects. IRE also led to inflammatory response characterized by tumor infiltration of myeloid cells and their polarization toward M1 state, turning immunologically "cold" tumors into "hot" tumors. Moreover, the presence of T cell/B cell clusters in tumors from mice treated with IRE plus PD-1 and the lack of antitumor efficacy in B cell knockout mice bearing orthotopic murine PDAC tumors indicate that B cells play an important role in IRE-mediated systemic antitumor immunity. SignificanceThis study shows that IRE plus a checkpoint inhibitor represents a promising therapeutic strategy for PDAC and supports advancing this treatment toward clinical translation. Our data also support potential combination strategies with immunomodulatory agents that can recruit and reprogram B cells to support T cell activation and cytotoxic effector functions.

Diffuse large B-cell lymphoma (DLBCL) is a common aggressive form of Non-Hodgkin lymphoma. Tetraspanin CD37 is highly expressed on mature B cells and being studied as a therapeutic target for NHL, including DLBCL. DuoHexaBody-CD37 is a biparatopic antibody with an E430G hexamerization-enhancing mutation targeting two non-overlapping CD37 epitopes shown to promote complement-dependent cytotoxicity. However, the impact of DuoHexaBody-CD37 on direct cytotoxic signaling has not yet been studied. Here we demonstrate that DuoHexaBody-CD37 induces direct cytotoxicity in DLBCL-derived tumor cell lines independent of the subtype. DuoHexaBody-CD37 induced significant CD37 clustering and was retained at the cell surface in contrast to rituximab, which was internalized. Unbiased screening identified the modulation of 26 (phospho)proteins upon DuoHexaBodyCD37 treatment of primary B cells or DLBCL cells. Whereas DLBCL cells predominantly upregulated p-SHP1(Y564) upon DuoHexaBody-CD37 treatment, primary B cells showed significantly increased p-AKT(S473) and MAPK signaling which is linked to cell survival. Studies using CD37-mutants identified the N-terminus to be involved in DuoHexaBody-CD37-induced signaling. Finally, DuoHexaBody-CD37 treatment inhibited cytokine pro-survival signaling in DLBCL cells. These findings provide novel insights into the signaling functions of CD37 upon DuoHexaBody-CD37 treatment, and open up opportunities for developing CD37-targeted immunotherapy in combination with small molecule inhibitors to maximize tumor cell death.

T cell lymphomas (TCL) are a heterogeneous collection of malignancies whose origins and pathogenesis are poorly understood and for which few efficacious therapeutic options exist. Here, we conduct single-cell transcriptomic profiling spanning eight TCL entities and describe entity-associated programmes. We predict the cell of origin for these tumours through an integrative analysis of transcriptome and T cell receptor (TCR) maturation states. By identifying tumours with TCR states ranging from the pre-TCR through non-productive and productive TCR alpha and beta chain rearrangements we shed new light on their developmental origins. Furthermore, we apply our drug2cell computational drug target predictions with drug screens using patient-derived cell models, systematically benchmarking the performance of drug2cell and validating compounds and targets. This process identifies SYK inhibitors as a therapeutic opportunity and prioritises TIM3 for immunotherapy based on combined spatial transcriptomics analysis. Overall, our data provide a resource for diagnostics and therapies for tumours of critical unmet need.

An immunosuppressive tumor microenvironment limits therapeutic efficacy and worsens prognosis in melanoma. Beyond T-cell abundance and function, effective tumor control also depends on whether T cells can access malignant cells within the tumor. Although emerging evidence supports that tumor vasculature facilitates immune evasion, the vascular mechanisms that govern intratumoral T-cell positioning remain poorly defined. Using RNA sequencing of endothelial cells isolated from tumor cores versus peripheries in a mouse melanoma model, we identified intercellular adhesion molecule 1 (ICAM-1) as a candidate regulator of T-cell localization. During tumor growth, T cells shifted from a balanced core-margin distribution to marked exclusion from the core, most prominently in T cell-inflamed tumors. This spatial redistribution --less evident in other immune subsets--coincided with high expression of lymphocyte function-associated antigen-1 (LFA-1) on T cells. In parallel, endothelial ICAM-1 became enriched at the tumor periphery, where vascular integrity was compromised, as evidenced by increased vascular leakage and reduced pericyte coverage. Functionally, ICAM-1 blockade restored intratumoral T-cell infiltration, enhanced effector activity, and significantly delayed the growth of immunogenic tumors. Moreover, ICAM-1 inhibition sensitized an immune-refractory tumor to anti-PD-1 checkpoint blockade. Together, these findings identify endothelial ICAM-1 as a vascular determinant of intratumoral T-cell positioning and highlight the ICAM-1/LFA-1 axis as a modifiable checkpoint to reverse T-cell retention at the tumor periphery, thereby enhancing antitumor immunity and immunotherapy efficacy.

High-grade serous ovarian cancer (HGSOC) represents 75% of ovarian cancer cases and 80% of deaths, with most patients relapsing despite initial treatment response. The limited effectiveness of immunotherapies in HGSOC indicates urgent need for novel therapeutic approaches. HGSOC patients produce tumor-binding autoantibodies (TBAs) with high tumor selectivity. Since effective antibody-mediated tumor cell killing requires Fc domain interactions with immune cells, we hypothesized that, although TBAs recognize tumor cells, they might still poorly elicit cell killing responses. Using a systems serology approach, we profiled TBA subclass and biophysical interactions with Fc receptors in HGSOC, comparing them to antiviral antibody responses. TBAs were consistently identified within ascites and serum and were heterogeneous in subclass composition. However, TBAs consistently lacked the capacity to bind Fc{gamma}RIIIa despite abundant interaction with Fc{gamma}RIIa and poorly elicited antibody-dependent cellular cytotoxicity, suggesting their Fc features prevent cell killing responses. Restoring Fc{gamma}RIIIa interaction may be a promising therapeutic approach in HGSOC. HighlightsO_LITBAs in ovarian carcinoma patients consistently lack interaction with Fc{gamma}RIIIa C_LIO_LIAscites- and serum-derived TBAs have heterogeneous subclass composition C_LIO_LISystems analysis shows complex serologic differences between TBAs and antiviral responses C_LIO_LIPatient-expressed TBAs demonstrate little antibody-dependent cellular cytotoxicity C_LI