Cancer Immunology Research

IL6 Induces an IL22+ CD8+ T-cell Subset with Potent Antitumor Function

Abstract CD8+ T cells can be polarized into several different subsets as defined by the cytokines they produce and the transcription factors that govern their differentiation. Here, we identified the polarizing conditions to induce an IL22-producing CD8+ Tc22 subset, which is dependent on IL6 and the aryl hydrocarbon receptor transcription factor. Further characterization showed that this subset was highly cytolytic and expressed a distinct cytokine profile and transcriptome relative to other subsets. In addition, polarized Tc22 were able to control tumor growth as well as, if not better than, the traditional IFNγ-producing Tc1 subset. Tc22s were also found to infiltrate the tumors of human patients with ovarian cancer, comprising up to approximately 30% of expanded CD8+ tumor-infiltrating lymphocytes (TIL). Importantly, IL22 production in these CD8+ TILs correlated with improved recurrence-free survival. Given the antitumor properties of Tc22 cells, it may be prudent to polarize T cells to the Tc22 lineage when using chimeric antigen receptor (CAR)-T or T-cell receptor (TCR) transduction–based immunotherapies.

Identification and Phenotypic Characterization of Neoantigen-Specific Cytotoxic CD4+ T Cells in Endometrial Cancer

Abstract Tumor-reactive CD4+ T cells often accumulate in the tumor microenvironment (TME) in human cancer, but their functions and roles in antitumor responses remain elusive. Here, we investigated the immunopeptidome of HLA class II–positive (HLA-II+) endometrial cancer with an inflamed TME using a proteogenomic approach. We identified HLA-II neoantigens, one of which induced polyclonal CD4+ tumor-infiltrating lymphocyte responses. We then experimentally demonstrated that neoantigen-specific CD4+ tumor-infiltrating lymphocytes lyse target cells in an HLA-II–dependent manner. Single-cell transcriptomic analysis of the TME coupled with T-cell receptor sequencing revealed the presence of CD4+ T-cell clusters characterized by CXCL13 expression. The CXCL13+ clusters contained two subclusters with distinct cytotoxic gene expression patterns. The identified neoantigen-specific CD4+ T cells were found exclusively in one of the CXCL13+ subclusters characterized by granzyme B and CCL5 expression. These results demonstrate the involvement of tumor-reactive CD4+ T cells with cytotoxic function in immune surveillance of endometrial cancer and reveal their transcriptomic signature.

Immune Modulation of Innate and Adaptive Responses Restores Immune Surveillance and Establishes Antitumor Immunologic Memory

Abstract Current immunotherapies have proven effective in strengthening antitumor immune responses, but constant opposing signals from tumor cells and the surrounding microenvironment eventually lead to immune escape. We hypothesized that in situ release of antigens and regulation of both the innate and adaptive arms of the immune system would provide a robust and long-term antitumor effect by creating immunologic memory against tumors. To achieve this, we developed CARG-2020, a genetically modified virus-like vesicle (VLV) that is a self-amplifying RNA with oncolytic capacity and encodes immune regulatory genes. CARG-2020 carries three immune modulators: (i) the pleiotropic antitumor cytokine IL12, in which the subunits (p35 and p40) are tethered together; (ii) the extracellular domain (ECD) of the protumor IL17RA, which serves as a dominant-negative antagonist; and (iii) a shRNA targeting PD-L1. Using a mouse model of ovarian cancer, we demonstrated the oncolytic effect and immune-modulatory capacities of CARG-2020. By enhancing IL12 and blocking IL17 and PD-L1, CARG-2020 successfully reactivated immune surveillance by promoting M1, instead of M2, macrophage differentiation, inhibiting MDSC expansion and establishing a potent CD8+ T cell–mediated antitumoral response. Furthermore, we demonstrated that this therapeutic approach provided tumor-specific and long-term protection against the establishment of new tumors. Our results provide a rationale for the further development of this platform as a therapeutic modality for ovarian cancer patients to enhance antitumor responses and prevent a recurrence.

The SETDB1–TRIM28 Complex Suppresses Antitumor Immunity

Abstract The tumor immune microenvironment is influenced by the epigenetic landscape of the tumor. Here, we have identified the SETDB1–TRIM28 complex as a critical suppressor of antitumor immunity. An epigenetic CRISPR–Cas9 screen of 1,218 chromatin regulators identified TRIM28 as a suppressor of PD-L1 expression. We then revealed that expression of the SETDB1–TRIM28 complex negatively correlated with infiltration of effector CD8+ T cells. Inhibition of SETDB1–TRIM28 simultaneously upregulated PD-L1 and activated the cyclic GMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) innate immune response pathway to increase infiltration of CD8+ T cells. Mechanistically, SETDB1–TRIM28 inhibition led to micronuclei formation in the cytoplasm, which is known to activate the cGAS–STING pathway. Thus, SETDB1–TRIM28 inhibition bridges innate and adaptive immunity. Indeed, SETDB1 knockout enhanced the antitumor effects of immune checkpoint blockade with anti–PD-L1 in a mouse model of ovarian cancer in a cGAS-dependent manner. Our findings establish the SETDB1–TRIM28 complex as a regulator of antitumor immunity and demonstrate that its loss activates cGAS–STING innate immunity to boost the antitumor effects of immune checkpoint blockade.

B7-H3 Suppresses Antitumor Immunity via the CCL2–CCR2–M2 Macrophage Axis and Contributes to Ovarian Cancer Progression

Abstract New approaches beyond PD-1/PD-L1 inhibition are required to target the immunologically diverse tumor microenvironment (TME) in high-grade serous ovarian cancer (HGSOC). In this study, we explored the immunosuppressive effect of B7-H3 (CD276) via the CCL2–CCR2–M2 macrophage axis and its potential as a therapeutic target. Transcriptome analysis revealed that B7-H3 is highly expressed in PD-L1–low, nonimmunoreactive HGSOC tumors, and its expression negatively correlated with an IFNγ signature, which reflects the tumor immune reactivity. In syngeneic mouse models, B7-H3 (Cd276) knockout (KO) in tumor cells, but not in stromal cells, suppressed tumor progression, with a reduced number of M2 macrophages and an increased number of IFNγ+CD8+ T cells. CCL2 expression was downregulated in the B7-H3 KO tumor cell lines. Inhibition of the CCL2–CCR2 axis partly negated the effects of B7-H3 suppression on M2 macrophage migration and differentiation, and tumor progression. In patients with HGSOC, B7-H3 expression positively correlated with CCL2 expression and M2 macrophage abundance, and patients with B7-H3–high tumors had fewer tumoral IFNγ+CD8+ T cells and poorer prognosis than patients with B7-H3–low tumors. Thus, B7-H3 expression in tumor cells contributes to CCL2–CCR2–M2 macrophage axis–mediated immunosuppression and tumor progression. These findings provide new insights into the immunologic TME and could aid the development of new therapeutic approaches against the unfavorable HGSOC phenotype.

Mechanisms Driving Neutrophil-Induced T-cell Immunoparalysis in Ovarian Cancer

Abstract T-cell activation and expansion in the tumor microenvironment (TME) are critical for antitumor immunity. Neutrophils in the TME acquire a complement-dependent T-cell suppressor phenotype that is characterized by inhibition of T-cell proliferation and activation through mechanisms distinct from those of myeloid-derived suppressor cells. In this study, we used ascites fluid supernatants (ASC) from patients with ovarian cancer as an authentic component of the TME to evaluate the effects of ASC on neutrophil function and mechanisms for neutrophil-driven immune suppression. ASC prolonged neutrophil life span, decreased neutrophil density, and induced nuclear hypersegmentation. Mass cytometry analysis showed that ASC induced 15 distinct neutrophil clusters. ASC stimulated complement deposition and signaling in neutrophils, resulting in surface mobilization of granule constituents, including NADPH oxidase. NADPH oxidase activation and phosphatidylserine signaling were required for neutrophil suppressor function, although we did not observe a direct role of extracellular reactive oxygen species in inhibiting T-cell proliferation. Postoperative surgical drainage fluid also induced a complement-dependent neutrophil suppressor phenotype, pointing to this effect as a general response to injury. Like circulating lymphocytes, ASC-activated neutrophils caused complement-dependent suppression of tumor-associated lymphocytes. ASC-activated neutrophils adhered to T cells and caused trogocytosis of T-cell membranes. These injury and signaling cues resulted in T-cell immunoparalysis characterized by impaired NFAT translocation, IL2 production, glucose uptake, mitochondrial function, and mTOR activation. Our results demonstrate that complement-dependent priming of neutrophil effector functions in the TME induces a T-cell nonresponsiveness distinct from established checkpoint pathways and identify targets for immunotherapy. See related Spotlight by Cassatella, p. 725.

KDM5A Inhibits Antitumor Immune Responses Through Downregulation of the Antigen-Presentation Pathway in Ovarian Cancer

Abstract The extent to which effector CD8+ T cells infiltrate into tumors is one of the major predictors of clinical outcome for patients with epithelial ovarian cancer (EOC). Immune cell infiltration into EOC is a complex process that could be affected by the epigenetic makeup of the tumor. Here, we have demonstrated that a lysine 4 histone H3 (H3K4) demethylase, (lysine-specific demethylase 5A; KDM5A) impairs EOC infiltration by immune cells and inhibits antitumor immune responses. Mechanistically, we found that KDM5A silenced genes involved in the antigen processing and presentation pathway. KDM5A inhibition restored the expression of genes involved in the antigen-presentation pathway in vitro and promoted antitumor immune responses mediated by CD8+ T cells in vivo in a syngeneic EOC mouse model. A negative correlation between expression of KDM5A and genes involved in the antigen processing and presentation pathway such as HLA-A and HLA-B was observed in the majority of cancer types. In summary, our results establish KDM5A as a regulator of CD8+ T-cell infiltration of tumors and demonstrate that KDM5A inhibition may provide a novel therapeutic strategy to boost antitumor immune responses.

Myeloid Cells Orchestrate Systemic Immunosuppression, Impairing the Efficacy of Immunotherapy against HPV+ Cancers

Abstract Cancers induced by human papillomaviruses (HPV) should be responsive to immunotherapy by virtue of expressing the immunogenic oncoproteins E6/E7. However, advanced forms of cervical cancer, driven by HPV, are poorly responsive to immune response–enhancing treatments involving therapeutic vaccination against these viral neoantigens. Leveraging a transgenic mouse model of HPV-derived cancers, K14HPV16/H2b, we demonstrated that a potent nanoparticle-based E7 vaccine, but not a conventional “liquid” vaccine, induced E7 tumor antigen–specific CD8+ T cells in cervical tumor–bearing mice. Vaccination alone or in combination with anti-PD-1/anti-CTLA4 did not elicit tumor regression nor increase CD8+ T cells in the tumor microenvironment (TME), suggesting the presence of immune-suppressive barriers. Patients with cervical cancer have poor dendritic cell functions, have weak cytotoxic lymphocyte responses, and demonstrate an accumulation of myeloid cells in the periphery. Here, we illustrated that myeloid cells in K14HPV16/H2b mice possess potent immunosuppressive activity toward antigen-presenting cells and CD8+ T cells, dampening antitumor immunity. These immune-inhibitory effects inhibited synergistic effects of combining our oncoprotein vaccine with immune checkpoint–blocking antibodies. Our data highlighted a link between HPV-induced cancers, systemic amplification of myeloid cells, and the detrimental effects of myeloid cells on CD8+ T-cell activation and recruitment into the TME. These results established immunosuppressive myeloid cells in lymphoid organs as an HPV+ cancer–induced means of circumventing tumor immunity that will require targeted abrogation to enable the induction of efficacious antitumor immune responses.

Expansion of Candidate HPV-Specific T Cells in the Tumor Microenvironment during Chemoradiotherapy Is Prognostic in HPV16+ Cancers

Abstract Human papillomavirus (HPV) infection causes 600,000 new cancers worldwide each year. HPV-related cancers express the oncogenic proteins E6 and E7, which could serve as tumor-specific antigens. It is not known whether immunity to E6 and E7 evolves during chemoradiotherapy or affects survival. Using T cells from 2 HPV16+ patients, we conducted functional T-cell assays to identify candidate HPV-specific T cells and common T-cell receptor motifs, which we then analyzed across 86 patients with HPV-related cancers. The HPV-specific clones and E7-related T-cell receptor motifs expanded in the tumor microenvironment over the course of treatment, whereas non–HPV-specific T cells did not. In HPV16+ patients, improved recurrence-free survival was associated with HPV-responsive T-cell expansion during chemoradiotherapy.

Targeting LxCxE Cleft Pocket of Retinoblastoma Protein in Immunosuppressive Macrophages Inhibits Ovarian Cancer Progression

Abstract Ovarian cancer remains a major health threat with limited treatment options available. It is characterized by an immunosuppressive tumor microenvironment (TME) maintained by tumor-associated macrophages (TAM), hindering antitumor responses and immunotherapy efficacy. In this study, we showed that targeting retinoblastoma protein (Rb) by disruption of its LxCxE cleft pocket caused preferential cell death in Rbhigh M2-polarized or M2-like Rbhigh immunosuppressive TAMs by induction of endoplasmic reticulum stress, p53, and mitochondria-related cell death pathways. A reduction of protumor immunosuppressive macrophages from TME in vivo resulted in enhanced T-cell infiltration and T-cell antitumor response and inhibited cancer progression. We demonstrated increased Rb expression in TAMs in women with ovarian cancer, which was associated with poorer prognosis. Ex vivo, we showed analogous cell death induction by therapeutic Rb targeting in TAMs in post-surgery ascites from patients with ovarian cancer. Overall, our data identify the therapeutic targeting of the Rb LxCxE cleft pocket as a promising approach for ovarian cancer treatment through depletion of immunosuppressive Rbhigh TAMs and re-shaping of the TME immune landscape.

Adaptive NK Cells Exhibit Tumor-Specific Immune Memory and Cytotoxicity in Ovarian Cancer

Abstract Adaptive NK (aNK) cells have emerged as a subset of NK cells with memory-like properties and specific cytotoxicity, offering promising therapeutic potential in cancer immunotherapy. In this study, we explored the role of aNK cells in high-grade serous ovarian cancer, focusing on their ability to establish tumor-specific immune memory and effectively target autologous tumors. Through a combination of in silico, in vitro, and ex vivo approaches, we demonstrated that aNK cells, in contrast to conventional NK cells, exhibit recall responses, specific cytotoxicity, and preferential infiltration into the tumor microenvironment. Our data revealed that aNK cells interact with dendritic cells within the tumor microenvironment via the HLA-E/NKG2C axis and CXCR2 signaling, contributing to their memory formation and tumor-targeting capabilities. These findings suggest that aNK cells could serve as potent agents in NK cell–based immunotherapies, particularly in solid tumors such as high-grade serous ovarian cancer, in which they resist immunosuppressive signals and maintain robust antitumor activity. This study provides new insights into the adaptive-like properties of aNK cells, underscoring their potential for advancing cancer immunotherapy strategies.

Targeting Cancer-Associated Glycosylation for Adoptive T-cell Therapy of Solid Tumors

Abstract Chimeric antigen receptor (CAR) T-cell therapy has improved outcomes for patients with chemotherapy-resistant B-cell malignancies. However, CAR T-cell treatment of patients with solid cancers has been more difficult, in part because of the heterogeneous expression of tumor-specific cell surface antigens. In this study, we describe the generation of a fully human CAR targeting altered glycosylation in secretory epithelial cancers. The expression of the target antigen—the truncated, sialylated O-glycan Sialyl-Thomsen-nouveau (STn) antigen—was studied with a highly STn-specific antibody across various different tumor tissues. Strong expression was found in a high proportion of gastrointestinal cancers, including pancreatic cancers, and in gynecologic cancers, in particular ovarian and endometrial tumors. T cells expressing anti-STn CAR were tested in vitro and in vivo. Anti-STn CAR T cells showed activity in mouse models, as well as in assays with primary ovarian cancer samples. No considerable toxicity was observed in mouse models although some intraluminal expression of STn was found in gastrointestinal mouse tissue. Taken together, this fully human anti-STn CAR construct shows promising activity in preclinical tumor models, supporting its further evaluation in early clinical trials.

TLR5 Signaling Causes Dendritic Cell Dysfunction and Orchestrates Failure of Immune Checkpoint Therapy against Ovarian Cancer

Abstract Ovarian cancer accounts for more deaths than any other cancer of the female reproductive system. Patients who have ovarian tumors infiltrated with high frequencies of T cells are associated with a greater survival probability. However, therapies to revitalize tumor-associated T cells, such as PD-L1/PD-1 or CTLA4 blockade, are ineffective for the treatment of ovarian cancer. In this study, we demonstrate that for ovarian cancer, Toll-like receptor 5 (TLR5) signaling, for which the only known ligand is bacterial flagellin, governed failure of PD-L1 and CTLA4 blockade. Mechanistically, chronic TLR5 signaling on CD11c+ cells in vivo and in vitro impaired the differentiation of functional IL-12–producing XCR1+CD103+ conventional type 1 dendritic cells, biasing CD11c+ precursor cells toward myeloid subsets expressing high levels of PD-L1. This culminated in impaired activation of CD8+ T cells, reducing CD8+ T-cell function and ability to persist within the ovarian tumor microenvironment. Expansion of XCR1+CD103+ conventional type 1 dendritic cells in situ using Flt3L-Ig in combination with PD-L1 blockade achieved significant survival benefit in TLR5 knockout mice bearing ovarian tumors, whereas no benefit was observed in the presence of TLR5 signaling. Thus, we have identified a host-intrinsic mechanism leading to the failure of PD-L1 blockade for ovarian cancer, demonstrating that chronic TLR5 signaling on CD11c+ cells is a barrier limiting the efficacy of checkpoint therapy.

A Phase I Trial of Trebananib, an Angiopoietin 1 and 2 Neutralizing Peptibody, Combined with Pembrolizumab in Patients with Advanced Ovarian and Colorectal Cancer

Abstract Ovarian cancers and microsatellite stable (MSS) colorectal cancers are insensitive to anti–programmed cell death 1 (PD-1) immunotherapy, and new immunotherapeutic approaches are needed. Preclinical data suggest a relationship between immunotherapy resistance and elevated angiopoietin 2 levels. We performed a phase I dose escalation study of pembrolizumab and the angiopoietin 1/2 inhibitor trebananib (NCT03239145). This multicenter trial enrolled patients with metastatic ovarian cancer or MSS colorectal cancer. Trebananib was administered intravenously weekly for 12 weeks with 200 mg intravenous pembrolizumab every 3 weeks. The toxicity profile of this combination was manageable, and the protocol-defined highest dose level (trebananib 30 mg/kg weekly plus pembrolizumab 200 mg every 3 weeks) was declared the maximum tolerated dose. The objective response rate for all patients was 7.3% (90% confidence interval, 2.5%–15.9%). Three patients with MSS colorectal cancer had durable responses for ≥3 years. One responding patient’s colorectal cancer harbored a POLE mutation. The other two responding patients had left-sided colorectal cancers, with no baseline liver metastases, and genomic analysis revealed that they both had KRAS wild-type, ERBB2-amplified tumors. After development of acquired resistance, biopsy of one patient’s KRAS wild-type ERBB2-amplified tumor showed a substantial decline in tumor-associated T cells and an increase in immunosuppressive intratumoral macrophages. Future studies are needed to carefully assess whether clinicogenomic features, such as lack of liver metastases, ERBB2 amplification, and left-sided tumors, can predict increased sensitivity to PD-1 immunotherapy combinations.

The Spatial Structure of the Tumor Immune Microenvironment Can Explain and Predict Patient Response in High-Grade Serous Carcinoma

Abstract Ovarian cancer is the deadliest gynecologic malignancy, and therapeutic options and mortality rates over the last three decades have largely not changed. Recent studies indicate that the composition of the tumor immune microenvironment (TIME) influences patient outcomes. To improve spatial understanding of the TIME, we performed multiplexed ion beam imaging on 83 human high-grade serous carcinoma tumor samples, identifying approximately 160,000 cells across 23 cell types. From the 77 of these samples that met inclusion criteria, we generated composition features based on cell type proportions, spatial features based on the distances between cell types, and spatial network features representing cell interactions and cell clustering patterns, which we linked to traditional clinical and IHC variables and patient overall survival (OS) and progression-free survival (PFS) outcomes. Among these features, we found several significant univariate correlations, including B-cell contact with M1 macrophages (OS HR = 0.696; P = 0.011; PFS HR = 0.734; P = 0.039). We then used high-dimensional random forest models to evaluate out-of-sample predictive performance for OS and PFS outcomes and to derive relative feature importance scores for each feature. The top model for predicting low or high PFS used TIME composition and spatial features and achieved an average AUC score of 0.71. The results demonstrate the importance of spatial structure in understanding how the TIME contributes to treatment outcomes. Furthermore, the present study provides a generalizable roadmap for spatial analyses of the TIME in ovarian cancer research.

TIME for Endometrial Cancer: Advancements and Challenges in Therapeutic Targets for the Endometrial Cancer Tumor Immune Microenvironment

Abstract Endometrial cancer is the sixth most common cancer in women worldwide and the fourth most common cancer in women in the United States. In the United States, its incidence and mortality rates have continued to increase since the late 1990s. Endometrial cancer comprises most uterine corpus carcinomas and represents a heterogeneous group of cancers varying in pathology, histology, molecular biology, immunogenicity, and prognosis. Recently, the advancement of molecular classification and subsequent clinical trials have led to new FDA approvals for the use of immune checkpoint inhibitors in endometrial cancer. However, recurrent and advanced-stage endometrial cancer continues to demonstrate high morbidity and mortality, denoting an unmet need for innovative immunotherapeutic strategies. This review explores current concepts in the endometrial cancer tumor immune microenvironment, comparing antigenicity, immunosurveillance, and immunoregulation among molecular and histologic subtypes and providing insight into which subtypes may be particularly responsive to immunotherapy. Novel immunotherapeutic strategies targeting cancer antigens, emerging immune checkpoints, immunomodulatory cytokines, and tumor-infiltrating immune cells are described, and corresponding clinical trials are presented. Integrated approaches such as immunogenic modulation, which enhances tumor susceptibility to immune attack, and immune subset conditioning, which modifies suppressive immune components within the tumor immune microenvironment, are presented as promising avenues to render “cold” tumors responsive. Together, the immunotherapies reviewed here offer potential strategies for treating patients with advanced or refractory endometrial cancer.

Spatiotemporal Immune Landscape and Long-term Immune Memory in POLE-Mutant Endometrial Cancer at the Single-Cell Level

Abstract Polymerase epsilon–mutant (POLE-mut) endometrial cancers are characterized by a near 100% disease-specific survival rate, even when treated with surgery alone. This survival, combined with the ultramutated genome and high level of neoantigens in these tumors, indicates a substantial degree of immune control in preventing disease spread and recurrence. Although these features are intriguing, the analysis of immune infiltration in POLE-mut endometrial cancers has predominantly been confined to IHC studies. In this study, we used single-cell RNA and T-cell receptor sequencing to characterize the immune landscape of POLE-mut endometrial cancers. Moreover, we analyzed patient blood samples taken 2 to 8 years after curative treatment to assess the formation of long-term immune memory in circulation. We identified specialized tumor-infiltrating myeloid subsets at different stages of maturation, an array of lymphocytes ranging from immature to cytotoxic, and adaptive NK cells, as well as tumor-reactive exhausted and effector T cells, all contributing to a highly inflammatory antitumor response. Our analysis of blood samples taken years after curative treatment uncovered the presence of tumor-reactive T-cell clones that matched the primary tumor. This indicates the formation of systemic long-term memory immune responses in POLE-mut endometrial cancer survivors. Our study highlights the distinctive immunogenicity of POLE-mut endometrial cancer and identifies key features associated with persistent antitumor immunity that may contribute to prolonged, relapse-free survival.

Ex Vivo Immuno-Oncology Platform Reveals Spatial T-cell Infiltration Patterns Linked to ATR Inhibition Responses in High-Grade Serous Ovarian Cancer

Abstract Identifying new therapeutic approaches in high-grade serous ovarian cancer (HGSC) requires the development of more accurate preclinical models that replicate the patient-specific tumor and its microenvironment. To address this, we established immunocompetent patient-derived cultures (iPDC) for HGSC, cultured on a physiologically relevant human omentum gel matrix. We developed a high-throughput platform that combines drug testing, histologic analysis, genomic profiling, single-cell studies, and spatial biomarker discovery. Our results from 47 tumors showed that iPDCs recapitulated the tumor genomic and histologic characteristics while also retaining the intratumoral immune cells. The iPDC treatment responses correlated significantly with the patients’ clinical treatment responses. Using iPDCs and single-cell RNA sequencing, we identified potentially effective therapeutic options for patients with recurrent HGSC linked to distinct tumor cell states and mechanisms of resistance. High-throughput drug response profiling with single-cell imaging identified ataxia telangiectasia and Rad3-related inhibitor (ATRi) combined with an immunotherapy targeting autotaxin as a promising new combination treatment for HGSC. Using hyperplexed imaging and spatial analysis, we discovered that ATRi responses were associated with significant increases in both intra- and peritumoral T-cell infiltration, particularly in PD-1+ CD8+ T cells. Additionally, the ATRi-induced reactivation of CD8+ T cells was linked to spatial interactions with replication stress–positive tumor cells. Thus, our iPDC platform presents a representative high-throughput ex vivo model to advance precision oncology in HGSC, uncovering the ATRi-immunotherapy combination as a potentially effective therapeutic option for clinical translation.

Prognostic Integrated Image-Based Immune and Molecular Profiling in Early-Stage Endometrial Cancer

Abstract Optimum risk stratification in early-stage endometrial cancer combines clinicopathologic factors and the molecular endometrial cancer classification defined by The Cancer Genome Atlas (TCGA). It is unclear whether analysis of intratumoral immune infiltrate improves this. We developed a machine-learning, image-based algorithm to quantify density of CD8+ and CD103+ immune cells in tumor epithelium and stroma in 695 stage I endometrioid endometrial cancers from the PORTEC-1 and -2 trials. The relationship between immune cell density and clinicopathologic/molecular factors was analyzed by hierarchical clustering and multiple regression. The prognostic value of immune infiltrate by cell type and location was analyzed by univariable and multivariable Cox regression, incorporating the molecular endometrial cancer classification. Tumor-infiltrating immune cell density varied substantially between cases, and more modestly by immune cell type and location. Clustering revealed three groups with high, intermediate, and low densities, with highly significant variation in the proportion of molecular endometrial cancer subgroups between them. Univariable analysis revealed intraepithelial CD8+ cell density as the strongest predictor of endometrial cancer recurrence; multivariable analysis confirmed this was independent of pathologic factors and molecular subgroup. Exploratory analysis suggested this association was not uniform across molecular subgroups, but greatest in tumors with mutant p53 and absent in DNA mismatch repair–deficient cancers. Thus, this work identified that quantification of intraepithelial CD8+ cells improved upon the prognostic utility of the molecular endometrial cancer classification in early-stage endometrial cancer.

Targeting of Tumoral NAC1 Mitigates Myeloid-Derived Suppressor Cell–Mediated Immunosuppression and Potentiates Anti–PD-1 Therapy in Ovarian Cancer

Abstract Epithelial ovarian cancer is the most common type of ovarian cancer with a low rate of response to immunotherapy such as immune checkpoint blockade therapy. In this study, we report that nucleus accumbens–associated protein 1 (NAC1), a putative driver of epithelial ovarian cancer, has a critical role in immune evasion. We showed in murine ovarian cancer models that depleting or inhibiting tumoral NAC1 reduced the recruitment and immunosuppressive function of myeloid-derived suppressor cells (MDSC) in the tumor microenvironment, led to significant increases of cytotoxic tumor-infiltrating CD8+ T cells, and promoted antitumor immunity and suppressed tumor progression. We further showed that tumoral NAC1 directly enhanced the transcription of CXCL16 by binding to CXCR6, thereby promoting MDSC recruitment to the tumor. Moreover, lipid C20:1T produced by NAC1-expressing tumor cells fueled oxidative metabolism of MDSCs and promoted their immune-suppressive function. We also showed that NIC3, a small-molecule inhibitor of NAC1, was able to sensitize mice bearing NAC1-expressing ovarian tumors to anti–PD-1 therapy. Our study reveals a critical role for NAC1 in controlling tumor infiltration of MDSCs and in modulating the efficacy of immune checkpoint blockade therapy. Thus, targeting of NAC1 may be exploited to sensitize ovarian cancer to immunotherapy.

Tertiary Lymphoid Structures Are Associated with Enhanced Macrophage Activation and Immune Checkpoint Expression and Predict Outcome in Cervical Cancer

Abstract Cervical tumors are usually treated using surgery, chemotherapy, and radiotherapy and would benefit from immunotherapies. However, the immune microenvironment in cervical cancer remains poorly described. Tertiary lymphoid structures (TLS) were recently described as markers for better immunotherapy response and overall better prognosis in patients with cancer. We evaluated the cervical tumor immune microenvironment, specifically focusing on TLS, using combined high-throughput phenotyping, soluble factor concentration dosage in the tumor microenvironment, and spatial interaction analyses. We found that TLS presence was associated with a more inflammatory soluble microenvironment, with the presence of B cells as well as more activated macrophages and dendritic cells (DC). Furthermore, this myeloid cell activation was associated with the expression of immune checkpoints, such as PD-L1 and CD40, and the proximity of activated conventional type 2 DCs to CD8+ T cells, indicating better immune interactions and tumor control. Finally, we associated TLS presence, greater B-cell density, and activated DC density with improved progression-free survival, substantiating TLS presence as a potential prognostic marker. Our results provide evidence that TLS presence denotes cell activation and immunotherapy target expression.

Reverse Translation Identifies the Synergistic Role of Immune Checkpoint Blockade and IL15 to Enhance Immunotherapy of Ovarian Cancer

Abstract Immune checkpoint blockade (ICB) has changed the standard of care for many patients with cancer, yet no ICB is approved for ovarian cancer. We hypothesized that maintenance therapy with an IL15 “superagonist” (N-803) and ICB in combination could induce potent immune activation in ovarian cancer. Using flow cytometry, cytometry by time of flight analysis, and cytotoxicity assays, we analyzed patient samples from women with advanced epithelial ovarian cancer treated with N-803 for indications of PD-1/PD-L1 upregulation with this treatment. In addition, ICB and N-803 were evaluated in preclinical studies to determine the functional impact of combination therapy on natural killer (NK) cells in vitro and in vivo. We observed that N-803 stimulated initial NK-cell expansion in patient samples; however, proliferation was not sustained beyond 2 weeks despite continued treatment. This result was reverse translated back to the laboratory to determine the functional relevance of this finding. The addition of ICB with an antibody-dependent cellular cytotoxicity IgG1 antibody against PD-L1 (avelumab) or an IgG4 antibody against PD-1 (pembrolizumab) enhanced N-803 induced NK-cell function in vitro. Using models of human ovarian cancer and NK-cell adoptive transfer in mice, we showed enhanced antitumor control with N-803 and ICB, as well as a combination effect that enhanced NK-cell persistence and expansion in vivo. This work suggests that PD-1/PD-L1 blockade combined with IL15 signaling may overcome resistance to cytokine therapy in ovarian cancer.

Downregulation of HLA Class I Expression through HLA-A DNA Methylation Is Associated with Reduced CD8+ T-cell Infiltration in Cervical Cancer

Abstract Human leukocyte antigen class I (HLA-I) is central to tumor immune recognition, but its regulatory mechanisms in cervical cancer remain poorly understood. This study aimed to elucidate the impact of HLA-I regulatory mechanisms on CD8+ T-cell infiltration and identify distinct histotype-specific immune escape strategies across cervical cancer subtypes. Using 98 cervical cancer cases, including squamous cell carcinoma (SCC; n = 53), adenocarcinoma (n = 32), gastric-type adenocarcinoma (GAS; n = 5), small cell carcinoma (Small, n = 4), and mixed histologic types (n = 4), we examined the relationship between CD8+ T-cell infiltration patterns (categorized as infiltrated, excluded, or absent) and HLA-I expression, HLA-A DNA methylation, and HLA-I loss of heterozygosity (LOH). CD8+ T-cell infiltration patterns varied significantly by histologic subtype (P < 0.0001). SCC showed the highest frequency of the infiltrated pattern (73.6%), whereas GAS and Small predominantly displayed an absent pattern. Reduced CD8+ T-cell infiltration correlated with poor survival (P < 0.0001). HLA-I expression mirrored these trends being highest in SCC and lowest in Small and GAS. HLA-A DNA methylation emerged as a key driver of HLA-I downregulation, leading to reduced CD8+ infiltration (P < 0.05). In SCC, both HLA-A methylation and HLA-I LOH contributed to immune evasion; cases lacking these alterations exhibited the highest CD8+ T-cell infiltration levels (P < 0.01). This study identifies distinct HLA-I regulatory mechanisms in cervical cancer, highlighting HLA-A methylation—and particularly HLA-I LOH in SCC—as key drivers of immune evasion. These findings provide a foundation for developing predictive biomarkers and suggest that targeting these specific HLA-I regulatory mechanisms could enhance immunotherapy efficacy.

Bexmarilimab Activates Human Tumor-Associated Macrophages to Support Adaptive Immune Responses in Interferon-Poor Immune Microenvironments

Abstract Immune checkpoint inhibitors (ICI) show substantially greater efficacy in inflamed tumors characterized by preexisting T-cell infiltration and IFN signaling than in noninflamed “cold” tumors, which often remain immunotherapy resistant. The cancer immunotherapy bexmarilimab, which inhibits the scavenger receptor Clever-1 to release macrophage immunosuppression and activate adaptive immunity, has shown treatment benefit in subsets of patients with advanced solid malignancies. However, the mechanisms that determine bexmarilimab therapy outcome in individual patients are unknown. Here we characterized bexmarilimab response in ovarian cancer ascites macrophages ex vivo using single-cell RNA sequencing and demonstrated increased IFN signaling and CXCL10 secretion following bexmarilimab treatment. We further showed that bexmarilimab was most efficacious in macrophages with low baseline IFN signaling, as chronic IFNγ priming abolished bexmarilimab-induced TNFα release. These results highlight an approach to target immunologically cold tumors and to increase the likelihood of their subsequent response to ICIs.

Paclitaxel Induces Immunogenic Cell Death in Ovarian Cancer via TLR4/IKK2/SNARE-Dependent Exocytosis

Abstract Emerging evidence shows that the efficacy of chemotherapeutic drugs is reliant on their capability to induce immunogenic cell death (ICD), thus transforming dying tumor cells into antitumor vaccines. We wanted to uncover potential therapeutic strategies that target ovarian cancer by having a better understanding of the standard-of-care chemotherapy treatment. Here, we showed in ovarian cancer that paclitaxel induced ICD-associated damage-associated molecular patterns (DAMP, such as CALR exposure, ATP secretion, and HMGB1 release) in vitro and elicited significant antitumor responses in tumor vaccination assays in vivo. Paclitaxel-induced TLR4 signaling was essential to the release of DAMPs, which led to the activation of NF-κB–mediated CCL2 transcription and IkappaB kinase 2–mediated SNARE-dependent vesicle exocytosis, thus exposing CALR on the cell surface. Paclitaxel induced endoplasmic reticulum stress, which triggered protein kinase R–like ER kinase activation and eukaryotic translation initiation factor 2α phosphorylation independent of TLR4. Paclitaxel chemotherapy induced T-cell infiltration in ovarian tumors of the responsive patients; CALR expression in primary ovarian tumors also correlated with patients' survival and patient response to chemotherapy. These findings suggest that the effectiveness of paclitaxel relied upon the activation of antitumor immunity through ICD via TLR4 and highlighted the importance of CALR expression in cancer cells as an indicator of response to paclitaxel chemotherapy in ovarian cancer.

The Tumor Microenvironment of Clear-Cell Ovarian Cancer

Abstract Some patients with advanced clear-cell ovarian cancer (CCOC) respond to immunotherapy; however, little is known about the tumor microenvironment (TME) of this relatively rare disease. Here, we describe a comprehensive quantitative and topographical analysis of biopsies from 45 patients, 9 with Federation Internationale des Gynaecologistes et Obstetristes (FIGO) stage I/II (early CCOC) and 36 with FIGO stage III/IV (advanced CCOC). We investigated 14 immune cell phenotype markers, PD-1 and ligands, and collagen structure and texture. We interrogated a microarray data set from a second cohort of 29 patients and compared the TMEs of ARID1A-wildtype (ARID1Awt) versus ARID1A-mutant (ARID1Amut) disease. We found significant variations in immune cell frequency and phenotype, checkpoint expression, and collagen matrix between the malignant cell area (MCA), leading edge (LE), and stroma. The MCA had the largest population of CD138+ plasma cells, the LE had more CD20+ B cells and T cells, whereas the stroma had more mast cells and αSMA+ fibroblasts. PD-L2 was expressed predominantly on malignant cells and was the dominant PD-1 ligand. Compared with early CCOC, advanced-stage disease had significantly more fibroblasts and a more complex collagen matrix, with microarray analysis indicating “TGFβ remodeling of the extracellular matrix” as the most significantly enriched pathway. Data showed significant differences in immune cell populations, collagen matrix, and cytokine expression between ARID1Awt and ARID1Amut CCOC, which may reflect different paths of tumorigenesis and the relationship to endometriosis. Increased infiltration of CD8+ T cells within the MCA and CD4+ T cells at the LE and stroma significantly associated with decreased overall survival.

Proteogenomics Uncovers a Vast Repertoire of Shared Tumor-Specific Antigens in Ovarian Cancer

Abstract High-grade serous ovarian cancer (HGSC), the principal cause of death from gynecologic malignancies in the world, has not significantly benefited from advances in cancer immunotherapy. Although HGSC infiltration by lymphocytes correlates with superior survival, the nature of antigens that can elicit anti-HGSC immune responses is unknown. The goal of this study was to establish the global landscape of HGSC tumor-specific antigens (TSA) using a mass spectrometry pipeline that interrogated all reading frames of all genomic regions. In 23 HGSC tumors, we identified 103 TSAs. Classic TSA discovery approaches focusing only on mutated exonic sequences would have uncovered only three of these TSAs. Other mutated TSAs resulted from out-of-frame exonic translation (n = 2) or from noncoding sequences (n = 7). One group of TSAs (n = 91) derived from aberrantly expressed unmutated genomic sequences, which were not expressed in normal tissues. These aberrantly expressed TSAs (aeTSA) originated primarily from nonexonic sequences, in particular intronic (29%) and intergenic (22%) sequences. Their expression was regulated at the transcriptional level by variations in gene copy number and DNA methylation. Although mutated TSAs were unique to individual tumors, aeTSAs were shared by a large proportion of HGSCs. Taking into account the frequency of aeTSA expression and HLA allele frequencies, we calculated that, in Caucasians, the median number of aeTSAs per tumor would be five. We conclude that, in view of their number and the fact that they are shared by many tumors, aeTSAs may be the most attractive targets for HGSC immunotherapy.

Lactic Acidosis Together with GM-CSF and M-CSF Induces Human Macrophages toward an Inflammatory Protumor Phenotype

Abstract In established tumors, tumor-associated macrophages (TAM) orchestrate nonresolving cancer-related inflammation and produce mediators favoring tumor growth, metastasis, and angiogenesis. However, the factors conferring inflammatory and protumor properties on human macrophages remain largely unknown. Most solid tumors have high lactate content. We therefore analyzed the impact of lactate on human monocyte differentiation. We report that prolonged lactic acidosis induces the differentiation of monocytes into macrophages with a phenotype including protumor and inflammatory characteristics. These cells produce tumor growth factors, inflammatory cytokines, and chemokines as well as low amounts of IL10. These effects of lactate require its metabolism and are associated with hypoxia-inducible factor-1α stabilization. The expression of some lactate-induced genes is dependent on autocrine M-CSF consumption. Finally, TAMs with protumor and inflammatory characteristics (VEGFhigh CXCL8+ IL1β+) are found in solid ovarian tumors. These results show that tumor-derived lactate links the protumor features of TAMs with their inflammatory properties. Treatments that reduce tumor glycolysis or tumor-associated acidosis may help combat cancer.