Journal for ImmunoTherapy of Cancer

The accepted paradigm for both cellular and antitumor immunity relies upon tumor cell kill by CD8+ T cells recognizing cognate antigens presented in the context of target cell major histocompatibility complex class I (MHC I) molecules. Likewise, a classically described mechanism of tumor immune escape is tumor MHC-I downregulation. Here, we report that CD8+T cells maintain the capacity to kill tumor cells that are entirely devoid of MHC-I expression. This capacity proves to be dependent on interactions between T cell NKG2D and tumor NKG2D ligands (NKG2DL). Necessarily, tumor cell kill in these instances is antigen-independent, although prior T cell antigen-specific activation is required and can be furnished by myeloid cells or even neighboring MHC-replete tumors cells. These mechanisms are active in vivo in mice, as well as in vitro in human tumor systems, and are obviated by NKG2D knockout or blockade. Tumor cell killing following T cell NKG2D engagement is Fas-independent and appears to involve granzyme. These studies potentially obviate the long-advanced notion that downregulation of MHC-I is a viable means of tumor immune escape, and instead identify the NKG2D/NKG2DL axis as a novel therapeutic target for enhancing T cell-dependent anti-tumor immunity against MHC loss variants.

Invariant natural killer T cells (NKTs) have intrinsic anti-tumor properties that make them promising candidates for chimeric antigen receptor (CAR)-based immunotherapies. Transgenic cytokine expression has been shown to enhance the potency of cellular immunotherapies, and we hypothesized that co-expressing IL-18 alone or with IL-15 would boost CAR-NKT therapeutic potential. To test this hypothesis, we generated retroviral constructs expressing IL-15 and/or IL-18 with the inducible caspase 9 (iC9) safety switch and co-transduced them with a GD2-specific CAR into human NKTs. Co-expression of IL-18 or IL-15/IL-18 increased GD2.CAR-NKT in vitro cytotoxicity, proliferation, and cytokine secretion compared to IL-15 alone. In a metastatic neuroblastoma model, GD2.CAR-NKTs expressing constructs with IL-18 controlled tumor growth better than cells expressing IL-15 only, but mice in the IL-15/IL-18 group developed severe toxicities not observed in the IL-18-only group. Mechanistically, we found that IL-18 drives a distinct transcriptional profile from IL-15 in CAR-NKTs marked by lower expression of exhaustion gene signatures and enrichment of metabolism-related processes. Finally, targeted metabolomics revealed that IL-18 induces broad metabolic reprogramming in CAR-NKTs including enhancement of oxidative phosphorylation, glycolysis, glutaminolysis and purine metabolism. These results support the use of IL-18 in developing the next generation of cytokine-armed CAR-NKT cancer immunotherapy.

Immune cell-based immunotherapy has emerged as a promising strategy for both hematologic malignancies and solid tumors. The adaptive properties of T and B cells, namely, antigen specificity and long-term immune memory, form the foundation of approaches such as chimeric antigen receptor (CAR) T-cell therapy and tumor vaccines. In contrast, natural killer (NK) cells, traditionally classified as innate lymphocytes, have been appreciated primarily for their immediate cytotoxicity against tumor cells, but not for long-term memory-like responses. Recent evidence has revealed a subset of NK cells defined as adaptive NK cells (aNK) capable of developing adaptive features, particularly in response to cytomegalovirus (CMV) primarily, and more recently, to ovarian tumor-derived antigens. However, whether tumor-derived peptides can specifically induce NK cell memory, and the corresponding interaction patterns, remains largely unexplored. In this study, we employed a proteogenomic approach combining RNA sequencing (RNA-seq) with HLA-E immunoprecipitation to identify both canonical and non-canonical peptides presented by primary ovarian tumor cells. Among four tumor-derived neo-antigenic peptides, the 9-mer peptide APAPAPAPL demonstrated the strongest binding affinity to HLA-E and engagement with the NK receptors NKG2C/A. Functional in vitro assays confirmed that this peptide could induce memory-like NK cell responses, including antigen-specific recall activity and enhanced tumor cytotoxicity. Furthermore, structural modeling using AutoDock Vina and Rosetta Dock illustrated that peptides with similar binding capacity shared conserved interaction patterns and docking orientations. Together, this systemic study highlights a novel mechanism for inducing NK cell memory through tumor-derived neoantigens. It also paves the way for the development of NK cell-targeted cancer vaccines, representing a new direction in tumor immunotherapy beyond conventional T cell-centered strategies.

T cell bispecific antibodies (TCBs) have demonstrated promising results in patients with solid tumors. However, the underlying immunological and molecular mechanisms influencing these clinical outcomes require in depth evaluation. T cell exhaustion, a state induced by prolonged antigen exposure, is known to undermine T cell-based immunotherapies, though its specific impact on TCB efficacy remains unclear. In this study, we assessed the effectiveness of TCBs on tumor-specific T cells, focusing on their functional status. Utilizing a fully immunocompetent mouse model with a solid tumor expressing an immunogenic antigen, we showed that tumor-specific T cells acquire an exhausted phenotype and fail to expand under TCB treatment. By employing both mouse and human tumor-specific T cells in vitro, our study established that chronically stimulated tumor-specific T cells show impaired response to TCB treatment. The comparison of TCB efficacy in T cell-inflamed tumors with immunogenic antigens versus non-inflamed tumors with low antigen presence in mice revealed TCB success in solid tumors is more reliant on T cell functional fitness than on their abundance before treatment. The data also indicate that solid tumors with elevated levels of both, intratumoral regulatory T cells, and T cells expressing co-inhibitory receptors, show diminished responses to TCB therapy, aligning with similar observations described in hematological cancers. These findings highlight the critical role of T cell exhaustion due to chronic antigen exposure and illustrate that exhausted tumor-specific T cells are likely not the driver population redirected by TCBs for tumor elimination. Our research highlights the importance of maintaining T cell fitness and preventing T cell exhaustion to improve TCB therapy outcomes. This may help better identify patient populations with solid tumors that could benefit from TCB treatments most in clinical settings.

BackgroundMutation-derived neoantigens, typically identified in primary tumors, are emerging therapeutic targets for personalized cancer vaccines and adoptive T-cell therapies. However, clinical efficacy of neoantigen-directed therapies in patients with metastatic disease remains limited, partly due to inter-site genetic heterogeneity. We investigated whether ubiquitous neoantigens-derived from mutations shared across all tumor sites-could provide more effective, durable targets, particularly in patients undergoing resection of metastatic lesions. MethodsWhole-exome and RNA sequencing were performed on 14 tumor samples (primary and 13 synchronous nodal metastases) from a treatment-naive patient with pancreatic neuroendocrine tumor (PNET). Ubiquitous mutations were identified bioinformatically, and their immunogenicity assessed using in-vitro stimulation of autologous peripheral blood mononuclear cells followed by IFN-{gamma} ELISpot assay. Neoantigen-specific T-cell clonotypes were further identified by HLA-tetramer staining and single-cell RNA/TCR sequencing. Neoantigen-reactive clonotypes identified in peripheral blood were tracked across multiple metastatic sites using bulk TCR{beta} repertoire sequencing. ResultsAmong 1,195 non-synonymous mutations detected, eight were shared across all 14 tumor sites. Of these, one encoded a neoantigen that elicited a reproducible IFN-{gamma} ELISpot response in peripheral blood, confirming its immunogenicity. Further, we identified the corresponding neoantigen-reactive TCR clonotypes in blood. Comparison with bulk TCR{beta} repertoires from eight metastatic sites showed that these clonotypes were present in every site analyzed, with evidence of local clonal expansion. ConclusionThis study provides direct evidence that a single ubiquitous mutation-derived neoantigen can generate systemic T-cell responses and clonotype expansion across multiple metastatic sites in a TMB-low, TIL-low tumor. Our findings support incorporating mutation-sharing status across metastases as a key criterion for neoantigen selection in cancer vaccines and adoptive T-cell therapies. This approach could inform the design of neoantigen-directed immunotherapies in metastatic PNET and potentially other metastatic solid tumors. What is already known on this topicNeoantigen-directed therapies, such as personalized cancer vaccines or adoptive T-cell transfer, can induce anti-tumor responses but have shown limited success in metastatic disease. One major barrier is genetic heterogeneity between tumor sites, suggesting that targeting ubiquitous mutations-those shared across all tumor sites-may improve the efficacy of such therapies. What this study addsIn one patient with metastatic pancreatic neuroendocrine tumor involving 13 lymph nodes, we identified eight ubiquitous mutations, one of which generated a detectable neoantigen-specific T-cell response in blood. The corresponding T-cell clonotypes were found across all metastatic sites analyzed and showed evidence of clonal expansion, providing direct evidence of systemic and local recognition of a shared neoantigen in a TMB-low/TIL-low cancer. How this study might affect research, practice or policyThese findings support incorporating mutation sharing across metastases as a key criterion in neoantigen selection for cancer vaccines and adoptive T-cell therapies. This strategy could enhance the relevance and durability of neoantigen- directed approaches in patients with metastatic disease.

ContextImmune checkpoint inhibitors (ICIs) have revolutionized cancer treatment but are associated with immune-related adverse events (irAEs), including pituitary dysfunction. Combination immunotherapy with PD-1 and CTLA-4 inhibitors increases the risk of pituitary irAEs compared to PD-1 monotherapy; however, their detailed clinical characteristics remain unclear. ObjectiveTo clarify the clinical features of pituitary irAEs induced by combination immunotherapy. MethodsIn this retrospective cohort study, we compared patients treated with combination therapy of nivolumab and ipilimumab (Nivo/Ipi) to those receiving nivolumab monotherapy (Nivo). We analyzed clinical data including presenting symptoms, laboratory findings, pituitary MRI results, and coexisting irAEs. ResultsPituitary irAEs were more frequent in the Nivo/Ipi group (17.4%) than in the Nivo group (2.7%) and developed earlier (median onset: 63 vs. 153 days, respectively). All 15 patients in the Nivo group presented with isolated ACTH deficiency (IAD), whereas the Nivo/Ipi group included 8 cases of IAD and 8 cases of combined pituitary hormone deficiency (CPHD). In the Nivo/Ipi group, CPHD occurred significantly earlier than IAD (median onset: 40 vs. 84 days) and was associated with a higher incidence of headache and pituitary swelling on MRI. Furthermore, 75% of patients with CPHD also experienced non-endocrine irAEs. Two CPHD patients experienced worsening of symptoms and pituitary dysfunction following re-administration of Nivo/Ipi. ConclusionPituitary irAEs are more frequent and develop earlier in patients receiving Nivo/Ipi. CPHD and IAD, induced by this combination immunotherapy, exhibit distinct clinical courses. Recognizing these differences is crucial for the optimal management of pituitary irAEs during combination immunotherapy.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer, with limited therapeutic options and extremely high mortality rates. While immune checkpoint blockade (ICB) therapy is effective in many types of human cancers, responses in PDAC patients remain poor, partly due to the weak immunogenicity of PDAC tumors. We hypothesized that a whole-cell PDAC vaccine could improve anti-tumor responses if optimized to expose a more stimulatory repertoire of tumor antigens. To test this, we used murine Panc02 pancreatic cancer cells to screen several stress-inducing treatments (UV, hypoxia, heat shock, and hydrogen peroxide [H2O2]), among which low-dose oxidative stress (0.05% H2O2 for 2h) was identified as the optimal inducer of immunogenic cell death (including increased surface calreticulin, ERp57 exposure, HMGB1 release and MHC class I expression). We then prepared a whole-cell vaccine of fixed H2O2-treated Panc02 cells, which induced robust tumor-specific immunity in C57BL/6 mice bearing syngeneic Panc02 tumors. Vaccine-treated mice displayed a significant increase in tumor-reactive IFN{gamma}+ T cells, as well as extensive tumor infiltration by CD4 + and CD8 + T cells and NCR1+ NK cells. When used prophylactically, the vaccine significantly delayed tumor growth and extended survival, whereas therapeutic application markedly slowed tumor progression. Importantly, combining the whole-cell Panc02 vaccine with anti-PD-1 therapy induced complete tumor regression in a subset of animals. Together, these data demonstrate that controlled oxidative stress can convert autologous tumor cells into an effective whole-cell vaccine without the need for genetic modification or prior neoantigen identification, offering a scalable strategy for personalized immunotherapy in PDAC. STATEMENT OF SIGNIFICANCEThis study demonstrated that oxidative stress-induced immunogenic cell death reprograms pancreatic tumor cells to induce danger signaling and enhance antigen presentation, thereby promoting immune infiltration and sensitizing tumors to PD-1 blockade.

Immune checkpoint inhibitors can elicit deep and durable immune responses although most cancer patients fail to experience long-term remission. There is consensus that tumor hypoxia coordinates a multitude of underlying resistance mechanisms that contribute to treatment failure. Here we show that the clinical-stage hypoxia-activated prodrug tarloxotinib lowers tumor hypoxia 8-fold in the EGFR-dependent MB49 syngeneic tumor model, attracting a effector CD8+ T cell infiltrate into an oxygen enriched tumor microenvironment, leading to potentiation of checkpoint inhibitor activity. Various methodologies, including CD8+ T cell depletion and exogenous T cell priming confirmed that tarloxotinib has a positive impact on the function of activated CD8+ T cells. Whilst anti-PD-L1, anti-PD-1 and anti-CTLA-4 treatments all benefited from the remodeled tumor microenvironment, anti-PD-L1 was most responsive to tarloxotinib coadministration, providing a 100% complete response rate and >360% improvement in tumor growth delay (day 19; p<0.0001). This robust interaction was associated with MB49 tumor enrichment of CD8+ T cell infiltrate from 8% to 43% of the total CD45+ population. To further understand these promising observations, comparative RNA transcript analysis of 770 cancer/immune related genes in naive and tarloxotinib treated tumors highlighted the strong induction of gene clusters related to co-stimulatory signaling, cytokine/chemokine signaling, interferon signaling, immune cell adhesion/migration, antigen presentation and the lymphoid/myeloid compartments. Serum protein analysis confirmed upregulation of a mixture of cytokines/chemokines, including IL-6, IL-12p40, IFN{gamma}, G-CSF and MIP-1{beta}, amongst others. The source of this broad immunogenic response was identified as toll-like receptor 9 (TLR9) dependent, with the positive interaction between anti-PD-L1 and tarloxotinib blocked in MyD88 or TLR9 knockout mice. Further, the observed therapeutic interaction was still evident in MC38 and EG7.OVA syngeneic tumor models, both refractory to tarloxotinib by virtue of EGFR-signal independence. Consistent with the clinical experience of minimal systemic toxicities related to EGFR inhibition (e.g. diarrhea), mouse body weight loss was minimal across all in vivo studies and histopathology screening for evidence of lung fibrosis proved negative. Tarloxotinib therefore represents a systemically administered small molecule with an established clinical safety profile that is capable of activating TLR9 signaling within tumors whilst remodeling the microenvironment to facilitate efficacy of checkpoint blockade. What is already known on this topicSolid tumor resistance to immune checkpoint inhibitors (ICI) is orchestrated through a diverse collection of hypoxia-driven mechanisms. In preclinical models modifying the tumor microenvironment (TME) to lessen hypoxia typically improves responses to ICI. What this study addsTarloxotinib is a hypoxia-activated prodrug (HAP) of an irreversible EGFR/HER2 TKI that profoundly remodels the TME, both eliminating tumor hypoxia and elevating cytokine/chemokine production via a TLR9 dependent effect. Together, this results in a marked tumor influx of activated CD8+ T cells (and other TILs), that results in major improvements in the efficacy of ICIs, particularly anti-PD-L1. How this study might affect research, practice or policyTarloxotinib is the first example of a tumor-targeted small molecule TLR9 stimulant that restores ICI sensitivity in a range of syngeneic tumor models. Phase I/II data has demonstrated that tarloxotinib is well tolerated, with few EGFR-dependent (on-target) side-effects, reflecting minimization of normal tissue exposure with the tumor-targeted HAP approach. Importantly, it also optimizes tumor selective exposure, offering a compelling clinical rationale for evaluation of this combination in cancer patients experiencing ICI relapse or resistance.

Reproducing a physiologically relevant tumor microenvironment in vitro is essential for developing effective immunotherapeutic treatments. By integrating the use of combinatorial receptor blockade and organoid models we provide a deep functional understanding of CD155 and CD112 receptors in solid tumors and their impact on cellular immunotherapy and infiltration. CD226 showed plasticity in response to the environment, being able to switch between CD155 and CD112 depending on the ligand availability. In addition, CD226 drove NK cell infiltration into tumor tissues via CD155 and CD112 ligation, with CD226-CD112 interaction specifically promoting migration from the periphery to the core. Downregulation of CD155 and TIGIT induced by the tumor microenvironment and previous drug exposure reduced the long-term efficacy of TIGIT blockade. Taken together, our findings point towards using CD112R blockade in primary tumors to simultaneously enhance NK cell killing activity and promote infiltration into the tumor core via CD226 and CD112 interaction. ONE SENTENCE SUMMARYTumors shape the hierarchy of CD155-CD112 receptors, reducing TIGIT blockade efficacy, while CD226 drives NK infiltration and shows binding plasticity

BackgroundDurable treatments that benefit a wide pool of patients remain elusive for Non-small cell lung cancer (NSCLC). The success of immunotherapy in a subset of NSCLC patients highlights the potential contribution of immune response to anti-tumor immunity while underscoring a need for broadly applicable therapeutic strategies. HDAC inhibitors are a promising class of drugs whose immunomodulatory properties are now being appreciated. In the present study, we evaluated the effects of the HDAC6 inhibitor, ACY241 on lung tumor immune compartment with the goal of understanding the scope of its immunomodulatory properties and its therapeutic potential in combination with Oxaliplatin. MethodsLung adenocarcinoma-bearing mice were treated with ACY241 or vehicle after which the proportions and phenotype of tumor-associated T cells and macrophages were evaluated by comprehensive flow cytometric analysis. Bulk RNA-sequencing was also conducted on both cellular subsets to interrogate the transcriptomic changes associated with ACY241 treatment relative to vehicle controls. In vivo drug efficacy study was performed by administration of ACY241 and/or Oxaliplatin and assessing tumor growth and survival of tumor-bearing mice. Ex vivo functional studies was performed to assess tumor-associated T cell effector function as it correlates with measured outcomes. ResultsWe demonstrate that ACY241 promotes increased presence of T and NK cells in the lung tumors of treated mice. The tumor-associated T cells under ACY241 treatment displayed enhanced activation, proliferation, and effector profile. In addition, tumor-associated macrophages exhibited increased expression of MHC and co-stimulatory molecules while expression of inhibitory ligands were reduced. RNA-sequencing of both tumor-associated T cells and macrophages revealed significant genomic changes in both subsets that is consistent with ACY241-mediated enhancement of immune priming. These broad immunomodulatory properties of ACY241 were associated with significantly enhanced tumor-associated T cell effector functionality, robust anti-tumor response, and significantly prolonged survival of NSCLC-bearing mice when combined with the chemotherapy drug Oxaliplatin. ConclusionCollectively, our studies highlight the broad immunomodulatory effect of ACY241 as a promising HDAC6 inhibitor which coupled with Oxaliplatin promotes robust therapeutic outcomes in a pre-clinical model of NSCLC, providing compelling rationale for the clinical testing of this novel combinatorial regimen in NSCLC.

PurposeTo evaluate safety and immunogenicity of intramuscularly delivered personalized neoantigen synthetic long peptide (SLP) vaccines in patients with advanced solid tumors. Patients and MethodsIn this Phase I trial, 12 patients with advanced melanoma (n=9) or renal cell carcinoma (n=3) who could no longer access further standard treatments received intramuscular neoantigen SLP vaccines with poly-ICLC. Each vaccine contained [~]20 predicted neoantigen peptides. Adverse events were monitored throughout vaccination and follow-up. Immune profiling was performed at baseline and predefined post-vaccination time points. ResultsIntramuscular neoantigen vaccination was well tolerated, with only grade 1-2 local pain or fever and no immune-mediated toxicities. All participants developed de novo T-cell responses, detectable within one week. On average, 46% of peptides per patient were immunogenic, inducing both CD8 and CD4 neoantigen-specific responses. Patients previously treated with immune checkpoint inhibitors (ICIs) had higher baseline immunity but achieved comparable post-vaccination responses to ICI-naive patients. IFN-{gamma}-dominant CD8 and TNF--dominant CD4 responses were observed, along with increased effector memory differentiation. Two patients with higher CD8 TEMRA proportions were the longest survivors. Tumor biopsies revealed enhanced CD8 infiltration, and epitope spreading occurred in one of two evaluable cases. Analysis of 239 peptides showed greater immunogenicity for dual MHC I/II-binding, cysteine-containing, and in-frame indel- or low-VAF-derived mutations, while proline substitutions reduced responses. ConclusionsIntramuscular neoantigen SLP vaccination with poly-ICLC is safe and induces rapid, mutation-specific T-cell immunity with robust CD8 effector responses. These findings support intramuscular administration as a promising strategy for peptide-based cancer vaccines. Translational relevancePersonalized neoantigen vaccines offer a promising strategy to enhance tumor-specific immunity, but most prior studies using intradermal or subcutaneous delivery have shown limited induction of cytotoxic CD8 T cells. This study demonstrates that intramuscular administration of personalized neoantigen synthetic long peptide vaccines with poly-ICLC is safe, feasible, and capable of eliciting rapid, mutation-specific CD4 and CD8 T-cell responses in patients with advanced melanoma and renal cell carcinoma. Vaccine-induced immunity was dominated by IFN-{gamma}-producing cells and accompanied by a shift toward effector memory phenotypes. In selected cases, post-treatment tumor biopsies revealed increased CD8 infiltration. These findings support intramuscular delivery as a practical and effective platform for neoantigen-based cancer vaccine.

Antibody-drug conjugates (ADCs) have emerged as a transformative class of cancer therapeutics with important challenges still to be addressed. Combination of ADC with immunotherapy is a promising strategy but mechanisms and effective application remain to be determined. We evaluated ADC combinations with T cell engagers (TCEs) and checkpoint inhibitors (CPI). ADC-TCE combinations produced robust antitumor activity independent of antigen and payload and persisted despite ADC-related T cell loss. Efficacy was dominated by a direct effect of ADC on tumor cells. ADCs induced autophagy that upregulated TNF receptors (TNFRs) and mannose-6-phosphate receptors (M6PR). When ADCs were combined with TCEs TNF released by T cells was primarily responsible for potent antitumor effect of combination. In contrast, M6PR was dispensable for ADC-TCE activity but critical for combinations with CPI expanded antigen-specific T cells via enhanced granzyme B uptake. These data reveal a unifying, target- and payload-agnostic mechanism enabling rational ADC-immunotherapy combinations. SignificanceThis is first evidence that ADC-induced tumor cell autophagy via up-regulation of TNFR and M6PR could be responsible for potent antitumor effect of combination of ADC with TCE. TCEs exploit a TNF-TNFR axis, whereas antigen-specific T cells leverage granzyme B-M6PR uptake. This mechanistic framework explains broad ADC-TCE synergy and guides rational selection of ADC-immunotherapy combinations beyond checkpoint blockade.

Brain tumors and metastases have a poor prognosis due to the unique characteristics of the central nervous system (CNS) and tumor immune microenvironment (TIME). CNS tumors exhibit limited infiltration and activation of dendritic cells (DCs) in tumor tissue and tumor-draining lymph nodes (TdLN), which regulate immune responses influenced by factors in the TIME. The immune response in the brain is significantly different from the rest of the body, and although DC subtypes have been identified in mice and humans with brain tumors or metastases, little is known how they affect the response to immunotherapy. We investigated the immunoregulatory function of cervical DCs (DC-c) compared to peripheral DCs (DC-p) in TdLN. Our analysis revealed that DC-c have unique phenotypes and promoted regulatory T cell expansion and poorly cytotoxic CD8 T cells compared to DC-p. Furthermore, we identified OX40 as a modulator of immunoregulatory DC-c function, and Batf3 knockout confirmed the essential role of DC-c in mounting an immune response to brain tumors. Additionally, the expression of markers associated with mature regulatory DCs (mregDC) in TdLN was associated with immune regulation in the CNS and the response to OX40. Our findings highlight that immunotherapy interventions can modulate DC-cs immunoregulatory function, offering an innovative approach for optimized immunotherapy against CNS malignancies.

Pancreatic ductal adenocarcinoma (PDAC) remains a lethal malignancy with limited therapeutic options, underscoring the need for innovative treatments. Chimeric antigen receptor (CAR) therapy has transformed hematologic malignancies but faces key challenges in solid tumors, particularly on-target/off-tumor toxicity and antigen heterogeneity. Adapter CAR (AdCAR) platforms offer enhanced control by decoupling antigen recognition from CAR activation, enabling controllable, reversible, and multi-antigen targeting. Recent studies suggest AdCARs can function as an AND-gate using combinations of adapter molecules at controlled surface densities. This defines activation thresholds, termed the Surface Activation Matrix, that restricts full activation to tumor cells overexpressing the target antigen combination, thereby reducing off-tumor toxicity. In this study, we evaluated its applicability to PDAC using adapters targeting CD318, TSPAN8 and CD66c. We systematically evaluated single and combinatorial adapter dosing in co-culture assays with AsPC1 cells, in a donor-dependent manner. Low concentrations of individual adapters were non-cytotoxic, whereas combining them at identical sub-threshold doses restored potent tumor killing, demonstrating that AdCAR activation depends on cumulative adapter density rather than total amount. However, the activation threshold required for AND-gate cytotoxicity varied between donors, highlighting the need for patient-specific titration to achieve selective tumor killing. These findings validate that AdCAR T cell activity in PDAC can be finely tuned through adapter concentration and combinatorial targeting, enabling selective tumor recognition while minimizing on-target/off-tumor toxicity. This flexible, safety-oriented strategy supports targeting heterogeneous PDAC tumors, though donor-dependent variability remains a critical consideration for clinical implementation.

BackgroundBoosting the performance of chimeric antigen receptor T (CAR-T) cell therapy in solid tumors may provide a substantial advantage for cancer patients. Recognizing the vital role of the nuclear factor of activated T cells (NFAT) in T cell function, we hypothesized that the strategic regulation of NFAT activity by targeting c-Jun N-terminal Kinases (JNK) can bolster the tumor-eradicating potential of CAR-T cells. MethodsWe developed a lentivirally encoded short-hairpin RNA (shRNA) for stable knockdown of JNK in CAR-T cells. CAR-T cells targeting human epidermal growth factor receptor 2 (HER2) were produced from human peripheral blood. Functionality was tested in vitro and in two xenograft models of human ovarian cancer. ResultsJNK knockdown in CAR-T cells suppressed antigen-induced stimulation and helper T cell cytokine production, while enhancing anti-tumor cytotoxicity in vitro and in ovarian cancer xenograft experiments. Mechanistically, JNK knockdown led to elevated levels of granzyme B expression which could be recapitulated through overexpression of NFATc1, suggesting an NFATc1 dependent mechanism of action. ConclusionsJNK signaling is a significant regulator of CAR-T cell cytotoxicity, offering a potential strategy to directly enhance CAR-T effectiveness in human cancer therapies.

BackgroundThe triple-negative breast cancer (TNBC) microenvironment (TME) undergoes progressive reprogramming, transitioning from an early immune-active state to a late immune-suppressed state. While tumor cell plasticity has been extensively studied, the molecular plasticity of T cells in vivo remains poorly defined. ObjectivesTo characterize transcriptional changes in T cells during TNBC progression and identify stage-specific shifts in T cell function, polarization, and antigen-presenting cell (APC)-T cell interactions. ResultsTranscriptional analysis of T cells from BALB/c mice bearing 4T1 tumors at 1, 3, and 6 weeks revealed a decline in T cell-associated genes from 194 at 1 week to 156 at 6 weeks, with a significant late-stage loss of TCR diversity and contraction of natural killer T (NKT)- and {gamma}{delta} T cell-related transcripts. Cytokine and transcription factor dynamics reflected temporal T cell polarization: early (1 week) IL-12/{beta}-STAT4 signaling supports CD4+ type 1 T helper cell (Th1) and type 1 CD8+ cytotoxic T cell (Tc1) responses; intermediate (3 weeks) IL-21 and BCL6 expression suggest transient CD8+ cytotoxic follicular T cell (Tfc) skewing; and late (6 weeks) AhR and IL-1{beta} induction reflect interleukin 17/22 producing CD8+ T cell (Tc17/Tc22) transition. Pro-inflammatory cytokines and chemokines increased over time, while immunosuppressive mediators (e.g., IL-10) declined significantly. Antigen-presenting cell (APC)-T cell crosstalk deteriorated at 6 weeks, characterized by a reduction in the expression of co-stimulatory and APC genes. Despite an early dominance of M1-like macrophage signals (e.g., IL-12/{beta}), persistent expression of arginase 1 (ARG1) and other M2-associated genes indicated a stable tolerogenic niche. ConclusionsTNBC progression is characterized by progressive T cell functional decline, narrowing of TCR diversity, impaired APC-T cell interactions, and sustained macrophage-driven immunosuppression. These temporally coordinated immune shifts suggest tumor-driven adaptation toward immune evasion and identify potential windows for stage-specific immunotherapeutic intervention.

Tumor clearance by T cells is impaired by insufficient tumor antigen recognition, insufficient tumor infiltration, and the immunosuppressive tumor microenvironment (TME). Although targeted T cell therapy circumvents failures in tumor antigen recognition, suppression by the TME and failure to infiltrate the tumor can hinder tumor clearance. Checkpoint inhibitors (CPI) promise to reverse T cell suppression and can be combined with bispecific antibody armed T cell (BATs) therapy to improve clinical outcomes. We hypothesize that adoptively transferred T cell function may be improved by the addition of CPI if the inhibitory pathway is functionally active. This study develops a kinetic-dynamic model of killing of hormone receptor-positive (HR+) breast cancer cells mediated by BATs using single-cell transcriptomic and temporal protein data to identify T cell phenotypes and quantify inhibitory receptor expression. LAG3, PD-1, and TIGIT were identified as inhibitory receptors expressed by cytotoxic effector CD8 BATs upon exposure to HR+ breast cancer cell lines. These data were combined with real-time tumor cytotoxicity data in a multivariate statistical analysis framework to predict the relevant contributions of T cells expressing each receptor to tumor reduction. A mechanistic kinetic-dynamic mathematical model was developed and parametrized using protein expression and cytotoxicity data for in silico validation of the findings of the multivariate statistical analysis. The model corroborated the predictions of the multivariate statistical analysis which identified LAG3+ BATs as the primary effectors, while TIGIT expression dampened cytotoxic function. These results inform CPI selection for BATs combination therapy and provide a framework to maximize BATs anti-tumor function. What is already known on this topicBispecific antibody armed T cell (BATs) therapies are adoptive T cell therapies that can effectively reroute T cell cytotoxicity toward cancerous cells, but lack consistent and durable anti-tumor responses. Checkpoint proteins expressed on the surface of activated T cells dampen immune responses and can be overstimulated in solid tumors to hamper tumor clearance by T cells. Checkpoint inhibitor drugs can improve T cell anti-tumor response by blocking checkpoint protein signaling but are only effective if the targeted checkpoint protein is expressed on the T cell and activated in the tumor microenvironment, highlighting an opportunity to enhance BAT efficacy by combining treatment with synergistic CPI. What this study addsThis study characterizes dynamic, time-resolved patterns in checkpoint protein expression by breast cancer-targeting adoptive T cells and predicts the significance of high-prevalence checkpoint proteins on T cell function. It also demonstrates the use of multivariate statistic and mathematical modeling toward rational design of targets and timing strategies for synergistic combination therapies. How this study might affect research, practice, or policyThe output of this study provides justification for therapeutic strategies combining adoptive T cell therapies with checkpoint inhibitor drugs targeting TIGIT and LAG3 as a means of improving patient responses in HER2-/HR+ breast cancers.

Natural killer (NK) cells are key components of the immune response to viral infections and cancer. Their functions are controlled by activating and inhibitory killer-cell immunoglobulin-like receptors (KIR) which have MHC class I ligands. KIR2DS2 is an activating KIR, that binds conserved viral peptides in the context of HLA-C and has been associated with protective responses to both cancer and viral infections. We sought to investigate whether NK cells can be specifically activated in a peptide:MHC dependent manner to generate functional immune responses as a potential immunotherapeutic strategy. We developed a peptide-based KIR targeting DNA vaccine. Immunizing KIR-Tg mice with the vaccine construct generated in vivo peptide-specific activation of KIR2DS2-positive NK cells leading to canonical and cross-reactive peptide specific immune responses in vitro, and also in vivo inhibition of tumor growth. Using immunopeptidomics we identified that the nuclear export protein XPO1, which has been associated with a poor prognosis in many different human cancers, furnishes an HLA-C restricted cancer-associated peptide ligand for KIR2DS2-positive NK cells. We thus define a novel strategy to activate KIR in a peptide-specific manner and identify a rationale for its use in cancer immunotherapy. Significance statementNatural killer (NK) cells are known to have important roles in determining the outcomes of viral infections and cancer. The killer cell immunoglobulin-like receptors (KIR), and in particular the activating receptor KIR2DS2, have been associated with the outcome of a number of different human cancers. Specific activation of NK cells through KIR2DS2 is challenging because it shares high (>98%) sequence homology with related inhibitory KIR. We have used a peptide:MHC targeting strategy to activate NK cells through KIR2DS2 and identified a novel cancer-associated ligand for this receptor. The work provides a proof-of-concept for targeting NK cells through activating KIR as a cancer immunotherapy strategy.

Immune checkpoint therapy has produced remarkable improvements in the outcome for certain cancers. To broaden the clinical impact of checkpoint targeting, we devised a strategy that couples targeting of the cytokine-inducible SH2-containing (CIS) protein, a key negative regulator of interleukin (IL)-15 signaling, with chimeric antigen receptor (CAR) engineering of natural killer (NK) cells. This combined strategy boosted NK cell effector function through enhancing the Akt/mTORC1 axis and c-MYC signaling, resulting in increased aerobic glycolysis. When tested in a lymphoma mouse model, this combined approach improved NK cell anti-tumor activity more than either alteration alone, eradicating lymphoma xenografts without signs of any measurable toxicity. We conclude that combining CIS checkpoint deletion with CAR engineering promotes the metabolic fitness of NK cells in an otherwise suppressive tumor microenvironment. This approach, together with the prolonged survival afforded by CAR modification, represents a promising milestone in the development of the next generation of NK cells for cancer immunotherapy.

Natural killer (NK) cells have emerged as promising effectors in cancer immunotherapy due to their ability to recognize and eliminate tumor cells. To investigate the immunological memory and tumor reactivity of adaptive (a)NK cells in the context of desmoplastic tumors, we used human ovarian cancer as a model. Through in vitro culture systems resembling dendritic cell (DC)-mediated T cell activation, we demonstrated that aNK cells exhibit antigen-specific cytotoxic responses and memory generation towards ovarian tumor antigens. Furthermore, mature DCs presenting tumor-associated antigens induced the expansion of aNK cells, suggesting antigen-specific proliferation. Single-cell transcriptomics revealed a distinct genetic signature of aNK cells in tumor samples, characterized by a cytotoxic phenotype and interactions with myeloid cells, particularly DCs. The spatial analysis confirmed the intratumoral presence of aNK cells, with higher abundance in the tumor nest compared to conventional (c)NK cells. Functional assays demonstrated the cytotoxicity of expanded aNK cells against autologous ovarian tumors, accompanied by an activated receptor profile. Importantly, aNK cells displayed antigen-specific memory responses towards primary tumors, maintaining specificity over time. Blockade of NKG2C and HLA-E influenced aNK cell recall responses, indicating their roles in the adaptive NK cell immune memory. Additionally, CXCR2 was essential for efficient aNK cell migration toward tumors. These findings shed light on the therapeutic potential of aNK cells in ovarian cancer immunotherapy, highlighting their ability to develop immunological memory and effectively eradicate tumor cells.