Citations

Abstract Description Immunotherapy combinations can improve patient outcomes, yet the interactions within the tumor microenvironment (TME) that drive therapeutic synergy are poorly understood. Tumor establishment drives monocyte recruitment and differentiation into tumor-associated macrophages (TAMs), which have essential roles in coordinating immune responses and are thus attractive targets for therapeutic modulation. In a murine model of combination anti-PD-1 and anti-PD-L1 checkpoint blockade, tumor control was associated with increased infiltration of CD8+ T cells and M1-like repolarization of TAMs. Live-cell imaging of the tumor microenvironment revealed stable contacts between tumor-infiltrating CD8+ T cells and TAMs, in which the extent of the contact interfaces increased with combination immunotherapy. Treatment with anti-PD-L1 was able to increase macrophage expression of pro-inflammatory factors and phagocytic activity, suggesting a role for TAMs to reactivate CD8+ T cells in the TME. However, co-treatment with anti-PD-1 was ultimately necessary for tumor control, indicating the need for combination targeting of the TME. Funding Sources Mayo Clinic David and Margaret Grohne Cancer Immunotherapy Pilot Award Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description The PD-L1/PD-1 receptor pathway allows cancer cells to evade immune surveillance, yet only a small percentage of patients benefit from PD-1/PD-L1 inhibitors. This limited efficacy is likely due to gaps in our understanding of PD-1/PD-L1 biology, particularly the lesser-known intracellular roles of PD-L1 compared to its extracellular interactions. Our research found that intracellular PD-L1 functions as an RNA-binding protein, interacting with NBS1 and BRCA1 mRNAs to protect them from degradation, thereby increasing cellular resistance to DNA damage. Given that current PD-1/PD-L1 inhibitors have little effect on intracellular PD-L1, we aimed to develop new drugs targeting this pathway. We created a novel PD-L1 antibody that disrupts the binding of PD-L1 to CMTM6, promoting PD-L1 degradation via the lysosome instead of blocking the PD-1/PD-L1 interaction. This mechanism enables the antibody to inhibit intracellular PD-L1 functions, something conventional immunotherapies cannot achieve. In vivo studies demonstrated that our antibody significantly sensitized tumors to radiation and chemotherapy in patient-derived xenograft models. In a humanized immune-competent triple-negative breast cancer PDX model, it outperformed existing PD-L1 inhibitors, suggesting it enhances anti-tumor immunity through PD-L1 degradation. This novel antibody offers a promising dual approach by targeting both intracellular and extracellular PD-L1, providing a compelling new strategy for cancer therapy. Funding Sources This work was supported in part by the American Society for Radiation Oncology, the National Cancer Institute of the National Institutes of Health under Award Number CA203561, P50CA116201, K12 HD065987, HALT Cancer at X, NCI R21 CA197878 (HD), R01-AI095239 and NIAID R01 AI095239. Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description The efficacy of ICI and T cell-based therapies is dependent on sufficient killing of tumor cells by T cells. Thus, it’s critical for effector T cells to maintain their function and overcome metabolic stress within the tumor microenvironment. Our previous work in human resilient CD8+ T cells identified malic enzyme 1 (ME1) as a key enzyme that augments effector CD8+ T cells’ metabolic and functional fitness via increased ATP production and curbed ROS production. To further study ME1’s role in promoting CD8+ T cell resilience in vivo, we produced CD8-specific ME1 conditional knockout and transgenic (ME1 Tg) mouse models. In MC38, ME1 was upregulated in CD8+ T cells in TILs compared to those in spleen and ME1 loss in CD8+ T cells abrogated tumor responses to ICI. In ME1 Tg mice, MC38 had reduced tumor growth, while B16F10 tumors were sensitized to ICI. We observed lower ROS and increased lipid content in CD8+ T cells in the TILs of ME1 Tg mice, underscoring ME1’s role in activating alternative metabolic pathways to fuel mitochondrial respiration while keeping ROS in check. The association of ME1 with 6PGD, a key enzyme in the pentose phosphate pathway (PPP), implies its regulation of redox homeostasis in CD8+ T cells. Importantly, ME1 overexpression in TILs dramatically improved the efficacy of TIL therapy in treatment of established tumors. Overall, ME1 upholds T cell resilience in tumor tissues and provides a new therapeutic target to improve the efficacy of TIL therapy. Funding Sources This work was supported by the Mayo Clinic Center for Biomedical Discovery (to H.D.); the Mayo Clinic Cancer Center’s David F. and Margaret T. Grohne Cancer Immunology and Immunotherapy program (to H.D.); R01 AI095239 (to H.D.), R01 CA200551 (to H.D. and S.S.P.), and R01 CA256927 (to H.D.). Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Background Immune checkpoint therapies targeting programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) have been met with limited clinical responses in the treatment of patients of varying cancer types. Current US Food and Drug Administration (FDA)-approved therapies function to prevent PD-1 binding to PD-L1, thereby preventing T-cell suppression. However, these therapies fail to prevent PD-L1 intrinsic signaling and recycling, which can render these treatments ineffective. Moreover, most research primarily focuses on how these antibodies affect tumor cells and their interactions with T cells. Myeloid cells, which also express PD-L1 and influence T-cell responses, are integral to the efficacy of these therapies. However, strategies that can target these cells to boost antitumor responses have not been effective. Methods Our group has developed a new anti-PD-L1 antibody (H1A), which disrupts PD-L1 recycling and redirects it towards degradation. Due to the loss of available PD-L1 protein, H1A effectively prevents PD-L1 intrinsic signaling. Using in vivo humanized PD-1/PD-L1 mouse tumor models, we evaluated the therapeutic efficacy of H1A against current FDA-approved PD-L1 blocking antibodies. Using human-derived immune cell in vitro assays, we pinpoint the biological consequences of H1A-induced PD-L1 degradation in myeloid cells. Results H1A demonstrated improved tumor control and established immunological memory responses in vivo in the treatment of tumors with moderate immunogenicity that are less responsive to current immunotherapies. This was supported by enhanced activation of myeloid cells (major histocompatibility complex (MHC)-II and CD80) and frequencies of effector T-cell populations found intratumorally. Human myeloid cells treated with H1A were also observed to have increased activation (MHC-II and CD80) and cytokine secretion. Similar to our in vivo findings, human peripheral blood lymphocyte cultures demonstrated increased frequencies of effector T-cell populations and greater tumor cell killing. Conclusions This work highlights the importance of targeting PD-L1 recycling and intrinsic signaling, specifically in myeloid cells, to boost antitumor responses. Our studies suggest that H1A can provide a solution to the lack of responses seen with current therapeutics, while also revealing previously unknown intrinsic functions of PD-L1 in myeloid cells.

Abstract The effectiveness of T cell–based immunotherapy depends on durable T-cell responses that can efficiently eliminate tumor cells. NKG7 was discovered three decades ago as a protein associated with lytic granules. However, only studies published over the past 5 years have contributed substantially to our understanding of NKG7 in T-cell biology. NKG7 has been recognized as an important T-cell functional marker in responses to immune checkpoint inhibitor therapy and in the prognosis of certain cancers. Besides its role in the generation, trafficking, and release of lytic granules, which is critical for efficient T-cell cytotoxicity against tumor cells, NKG7 has been identified as a key negative regulator of mTORC1 activity. By restraining mTORC1 activity, NKG7 promotes T-cell longevity and memory generation after infection. Importantly, NKG7 upregulation has demonstrated therapeutic potential in preclinical T-cell therapy for cancer. Collectively, NKG7 is emerging as a promising biomarker and therapeutic addition to T cell–based immunotherapies.

Aims Schistosomiasis remains endemic in various parts of the world, and insights into pathogen immunobiology are mainly based on experimental models, while studies on human tissues are limited. Methods We explored the role of immune checkpoint pathway by evaluating the immunohistochemical expression of programmed death-ligand 1 (PD-L1) in a retrospective cohort of patients with bilharzial cystitis. Inflammation severity by conventional histology and staining intensity by immunohistochemistry were assigned three-tier scores (0/1+/2+), and a cut-off for staining percentage was set at 5%. Results 38 biopsies from 31 patients were considered adequate for evaluation, and positive staining was detected in 80.6% of patients (34 biopsies). High expressors (22.6%) showed strong positive membranous staining (score 2+) with high staining density (more than 5% of inflammatory cells). Low expressors (58.1%) showed mild/moderate staining (score 1+) predominantly in less than 5% of the cells (91.6%) or expressed restricted cytoplasmic staining (6/31). All high expressors showed severe inflammation (score 2+) (p<0.001), and viable ova were only observed in these cases. Calcified ova were associated with mild/moderate inflammation or absent/minimal inflammation, correlating with low expressors or non-expressors (19.4%), respectively. Conclusion Schistosomal granuloma exhibits upregulated PD-L1 expression proportional to inflammation severity and pathogen viability, highlighting a critical immune checkpoint engagement in disease pathology.

Abstract Extracellular vesicles (EV) are phospholipid‐encapsulated nanoparticles secreted by cells into their surrounding environment. EVs can transfer a variety of biomolecules that mediate intercellular communication and play a key role in physiological and pathological processes. Therefore, EVs are emerging as new biomarkers for diseases, therapeutic targets, and drug delivery vehicles. The isolation and detection of EVs requires time‐consuming and labor‐intensive processes, first to extract EVs from biological and physiological fluids and then to detect EV‐associated molecules with high sensitivity. The methodologies and instruments commonly used for EV analysis are not widely accessible outside of dedicated research laboratories, creating practical barriers for the study of EV‐associated molecules in biology research and clinical applications. To bridge this gap, we developed a proof‐of‐concept digital microfluidic device that can automatedly extract EVs from 20 µL of culture and human plasma samples within 25 min and detect EV‐bound proteins (e.g PD‐L1) on‐chip using an electrochemical sensor. This work serves as a framework for the development of streamlined EV analysis in both research and diagnostics.

Abstract The roles of nucleoplasm-residing nucleoporins (NUP) in solid tumors, including prostate cancer, remain unknown. In this study, we reveal the clinical significance and mechanistic role of the off-pore NUP, soluble POM121 (sPOM121), as a crucial transcriptional regulator that enhances the aggressiveness of metastatic prostate cancer. Using orthogonal methodologies in human samples, sPOM121 was identified as the predominantly expressed nucleoplasmic NUP in prostate cancer. Unbiased proteomic and epigenomic studies demonstrate that sPOM121, through its C-terminus, interacts with the chromatin remodeler SMARCA5 at gene promoter sites and localizes at nuclear condensates, reprogramming gene expression. Indeed, sPOM121 regulates a distinct oncogenic gene network, including β-catenin, leading to prostate cancer progression and immune evasion. Importantly, targeting the sPOM121/β-catenin axis in patient-derived preclinical and syngeneic mouse models halts prostate cancer aggressiveness and enhances antitumor immunity. Taken together, these findings reveal previously unknown actionable reprogramming functions of off-pore NUPs in solid tumors. Significance: This study uncovers how oncogenic signaling programs are transcriptionally heightened by the NUP sPOM121 in metastatic prostate cancer. Localization of sPOM121 at active transcriptional nuclear condensates propels disease progression and immune evasion, offering novel anticancer therapeutic opportunities.