Clinical datasets across versatile types of cancer indicate a strong association between B-cell tumor presence and cancer patients' responses and survival following immune checkpoint blockade. Indeed, many clinical observations have identified mature tumor associated tertiary lymphoid structure (TLS) with distinct B cell and T cell zones as a key determinant of patients' responses to immunotherapy. However, differences in clinical associations and B cells functions across tumor contextures necessitate in-depth investigations on context-dependent anti- and pro-tumorigenic roles of B-cell immunity-antibody secretion, antigen presentation, and cytokine production-and its importance for tumor control. Therapeutic strategies that promote B cell infiltration, TLS formation and maturation show promise in re-programing the tumor microenvironment, enhancing anti-tumor immunity, and promoting tumor clearance.

Both regulatory B (Breg) and myeloid cells in tumors and lymph nodes drive immune suppression in pancreatic cancer. Current strategies to counter immune suppression emphasize myeloid cells but overlook Breg cells. We discovered that STING agonist expanded Breg cells depended on PI3Kγ but not PI3Kδ in pancreatic cancer, whereas activating myeloid cells were independent of PI3Kγ. Inhibition of PI3Kγ, but not PI3Kδ, decreased STING-induced IRF3 phosphorylation and Breg cell expansion in pancreatic cancer, while sustaining STING-induced IRF3 phosphorylation to activate myeloid cells. We developed a dual targeting compound and its albumin nanoformulation Nano-273, which stimulated STING to activate myeloid cells and inhibited PI3Kγ to decrease STING-induced Breg cell expansion. Nano-273 delivered the drug to tumors and lymph nodes to overcome myeloid cell- and Breg cell-mediated immune suppression in pancreatic cancer. Nano-273, combined with anti-programmed cell death protein 1, achieved durable efficacy in transgenic KPC mice with pancreatic cancer, offering potential for pancreatic cancer treatment.

ABSTRACT Tumor‐associated immunosuppressive neutrophils, termed polymorphonuclear myeloid‐derived suppressor cells (PMN‐MDSCs), compromise cancer immunotherapy. Emerging evidence indicates that neutrophil fate can be programmed as early as the hematopoietic stem and progenitor cell (HSPC) stage. Reprogramming HSPCs toward antitumor neutrophils offers a promising therapeutic strategy. Here, we demonstrate that an albumin‐bound STING agonist (Nano ZSA‐51D) reprograms HSPCs to generate antitumor neutrophils, enhancing MHC I‐mediated CD8+ T cell immunity and sensitizing tumors to α‐PD1 immunotherapy. Nano ZSA‐51D expands HSPCs and reprograms them toward granulocyte‐monocyte progenitors for neutrophil development. It further converts immature (CD101−) and mature (CD101+) neutrophils into a CD14+ICAM‐1+ subset through STING‐NF‐κB–TNF‐α signaling, enhancing tumor infiltration and antitumor activity. These neutrophils upregulate interferon signaling and MHC I antigen presentation, thereby boosting tumor‐specific CD8+ T cell responses. Notably, both adoptive transfer of Nano ZSA‐51D‐reprogrammed neutrophils and systemic Nano ZSA‐51D treatment synergizes with α‐PD1 therapy to achieve complete remission of colon tumors through neutrophil‐ and CD8+ T cell‐dependent mechanisms, with potent efficacy also validated in otherwise immune‐resistant pancreatic cancer models. Our findings establish a therapeutic strategy to reprogram HSPCs toward antitumor neutrophils, highlighting the potential of targeting early hematopoiesis to rewire neutrophil fate in cancer immunotherapy.

Current neoantigen cancer vaccines activate T cell immunity through dendritic cell/macrophage-mediated antigen presentation. It is unclear whether incorporating B cell-mediated antigen presentation into current neoantigen vaccines could enhance CD4/CD8 T cell immunity to improve their anticancer efficacy. We developed SARS-CoV-2 B cell epitope-guided neoantigen peptide/mRNA cancer nanovaccines (BSARSTNeoAgVax) to improve anticancer efficacy by enhancing tumor-specific CD4/CD8 T cell antitumor immunity through B cell-mediated antigen presentation. BSARSTNeoAgVax cross-linked with B cell receptor, promoted SARS-CoV-2 B cell-mediated antigen presentation to tumor-specific CD4 T cells, increased tumor-specific follicular/nonfollicular CD4 T cells, and enhanced B cell-dependent tumor-specific CD8 T cell immunity. BSARSTNeoAgVax achieved superior efficacy in melanoma, pancreatic, and breast cancer models compared with the current neoantigen vaccines. Our study provides a universal platform, SARS-CoV-2 B epitope-guided neoantigen nanovaccines, to improve anticancer efficacy against various cancer types by enhancing CD4/CD8 T cell antitumor immunity through viral-specific B cell-mediated antigen presentation.

Current neoantigen cancer vaccines primarily rely on dendritic cell- and macrophage-mediated antigen presentation to activate T cell immunity. However, the potential of incorporating B cell-mediated antigen presentation into these vaccines to enhance CD4 and CD8 T cell responses has not been fully explored. We developed BSARSTNeoAgVax, a SARS-CoV-2 B cell epitope-guided neoantigen peptide or mRNA cancer nanovaccine, designed to leverage B cell-mediated antigen presentation. BSARSTNeoAgVax was tested in three mouse cancer models (melanoma, pancreatic cancer, and breast cancer) using two types of T cell tumor neoantigens (peptide or mRNA) and two types of nano delivery systems (I or lipid nanoparticles, LNP). SARS-CoV-2 B cell epitopes were conjugated on the surface of I or LNP to facilitate crosslinking with the B cell receptor (BCR) on SARS-CoV-2-specific B. Immune responses and therapeutic efficacy of BSARSTNeoAgVax were compared with existing neoantigen vaccines. BSARSTNeoAgVax enabled SARS-CoV-2 B cell-mediated antigen presentation to tumor-specific CD4 T cells, significantly enhancing the activation of tumor-specific follicular and non-follicular CD4 T cells. This interaction also promoted B cell-dependent tumor-specific CD8 T cell immunity, resulting in robust antitumor responses. Importantly, the efficacy of BSARSTNeoAgVax was independent of antibody production, as the SARS-CoV-2 B cell epitopes on the vaccine generated anti-SARS-CoV-2 antibodies that lacked anticancer efficacy. In the mouse cancer models, BSARSTNeoAgVax demonstrated superior efficacy, showing improved tumor control and enhanced immune activation compared to current neoantigen vaccines. Our findings establish a universal platform for cancer immunotherapy, utilizing SARS-CoV-2 B epitope-guided neoantigen nanovaccines to enhance CD4 and CD8 T cell antitumor immunity through viral-specific B cell-mediated antigen presentation. This approach holds significant promise for improving the efficacy of neoantigen-based cancer vaccines across diverse tumor types. Chengyi Li, Fang Ke, Shuai Mao, Zera Montemayor, Mohamed Dit Mady Traore, Alejandra Duran Balsa, Mahamadou Djibo, Neha Karekar, Hanning Wen, Wei Gao, Duxin Sun. Enhancing anticancer immunity with SARS-CoV-2 B cell epitope-guided neoantigen nanovaccines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3545.

The clinical application of BCL-2/xL inhibitors for cancer treatment is limited by the on-target thrombocytopenia. Although APG-1252 was designed to mitigate this issue, platelet toxicity at higher doses in clinical trials restricts dose escalation for greater efficacy. We have developed albumin nanocomplexes of APG-1252 (Nano-1252) to reduce platelet toxicity while improving drug efficacy through enhancing drug delivery to lymphoid organs. Nano-1252 forms stable nanoparticles due to the strong binding affinity between APG-1252 and albumin, reducing the platelet toxicity threshold by fourfold by limiting premature drug release and conversion to its active forms in circulation. Furthermore, Nano-1252 exhibited preferential accumulation in lymphoid organs, leading to enhanced anticancer efficacy in Mantle Cell Lymphoma (MCL) and Myeloproliferative Neoplasms (MPNs) mouse models. Our study not only develops a potential formulation to overcome the current translational barrier of APG-1252 but also reveals novel properties of the well-established albumin nanoformulation, thereby expanding its clinical applications.

Neutrophils, the most abundant leukocytes (50-70%) in human circulation, are key players in the innate immune response and increasingly recognized for their multifaceted roles in cancer biology. Beyond their established functions in infection control and inflammation, they have been shown to significantly influence tumor progression through complex interactions within the tumor microenvironment. Neutrophils exhibit remarkable phenotypic heterogeneity and plasticity, which allows them to adopt either tumor-suppressing or tumor-promoting functions. How to program neutrophils in vivo for anti-cancer therapy? We developed a systemically administrated STING agonist formulated within albumin formulation to activate neutrophils for anti-cancer immunotherapy. We synthesized a novel non-nucleotide STING agonist dimer ZSA-51D encapsulated in albumin nanoparticles (nano ZSA-51D), which exhibited a potent STING pathway activation in THP1-BlueTM ISG cells (EC 50 0.44 nM) and mouse myeloid cells (EC 50 < 10 nM). Interestingly, we found the Nano ZSA-51D highly activated CD101-CD14+ and CD101+CD14+ neutrophils in vitro and in vivo, which was STING pathway dependent. The pharmacokinetic studies in mice shown Nano ZSA-51D highly accumulated in bone marrow (BM). Most of the Nano ZSA-51D were absorbed by neutrophils in BM, blood and Tumor, which resulted in high neutrophil activation in vivo. The Nano ZSA-51D plus α-PD1 achieved complete remission in the MC-38 colon cancer and robust anti-cancer effects in pancreatic cancer model. The tumor immune cell infiltration was examined by flow cytometry at 24 h after treatments. We found the neutrophils were highly activated in BM and blood, then the activated (CD101-CD14+ and CD101+CD14+) neutrophils largely infiltrated into tumor after Nano ZSA-51D treatment. The bulk mRNA sequence analysis showed the neutrophils were activated through Toll-like receptor, TNF-α and NF-κB signaling pathway. Surprisingly, the activated CD101-CD14+ and CD101+CD14+ neutrophils enhanced the antigen presentation of exogenous peptide antigen via MHC class I, further promote the proliferation and activation of T cells, which shown robust anti-cancer effects in vivo after rejected the activated neutrophils into tumor. In this study, we developed a novel systemically administered STING agonist formulated within albumin formulation (Nano ZSA-51D) to activate neutrophils for anti-cancer immunotherapy. Nano ZSA-51 plus α-PD1, demonstrated superior anticancer efficacy through activating neutrophil to promote the proliferation and activation of T cells in vivo. Jinsong Tao, Hongyi Zhao, Chengyi Li, Zhongwei Liu, Hanning Wen, Qiuxia Li, Miao He, Bo Wen, Fang Ke, Wei Gao, Duxin Sun. A systemically administrated STING agonist in albumin formulation activated neutrophils for anti-cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 895.

Cancer vaccine has emerged as a promising therapeutic paradigm for cancer therapy. However, the lack of tumor-associated antigens and abundant immunosuppressive factors seriously diminish the efficacy of immunotherapy, resulting in poor clinical benefits. In this report, we engineered a coordinated immunostimulatory nanoplatform, termed MP@PPS NPs, by physically combining reactive oxygen species (ROS)-responsive poly (propylene sulfide) nanoparticles loaded with the photosensitizer pyropheophorbide a (PPa) and stimulator of interferon genes (STING) agonist (MSA-2), to function as an in situ cancer vaccine to amplify immunotherapeutic outcomes. Excellent stability of MP@PPS NPs endowed prolonged drug circulation time and improved tumor accumulation, while their small size boosted deeper drug penetration within tumors. Crucially, upon laser irradiation, the MP@PPS NPs could generate abundant ROS, which induced tumor ablation, triggered immunogenic cell death to initiate an adaptive antitumor immune response and facilitated the local release of MSA-2, thereby promoting innate antitumor immunity through the cGAS-STING pathway. MP@PPS NPs markedly suppressed both primary and distant tumor progression, promoted dendritic cell maturation and increased cytotoxic T lymphocyte infiltration, elicited robust antitumor immunity. Meanwhile, MP@PPS NPs treatment impeded the lung metastatic in conjunction with anti-PD-L1 treatment. This work holds significant promise for the synergistic photodynamic immunotherapy, and offers a crucial inspiration for addressing the problems of insufficient antitumor immunity and ineffective cancer treatments.

Phosphoinositide 3-kinases (PI3Ks) are crucial for cell growth, survival, and metabolism, with dysregulated signaling common in cancer. The PI3K family includes four isoforms—PI3Kα, PI3Kβ, PI3Kδ, and PI3Kγ—each with distinct roles, where pan-PI3K inhibition often results in toxicity due to broad isoform expression. Existing various PI3K isoform inhibitors, despite in vitro specificity, often act as pan-inhibitors at high in vivo clinical effective concentrations (1μ M to 5μ M). We developed a highly selective PI3Kγ inhibitor that retains its specificity even at therapeutic in vivo levels, effectively targeting tumor immunosuppressive environment to inhibit tumor growth, while reducing toxicity associated with pan-PI3K inhibitions. Newly synthesized compounds were screened for PI3K isoform selectivity by kinase binding assays. After oral administration (p.o.), tissue distribution studies compared lead compounds with IPI-549 across various tissues, including tumor, spleen, tumor-draining lymph nodes (TDLNs), plasma and liver. The lead PI3Kγ inhibitors were further evaluated in vivo using MC38 colon cancer model and MMTV-PyMT breast cancer model, in both monotherapy (p.o.) and combination therapy with paclitaxel (PTX) or anti-PD-1 antibody (aPD-1). Immune cell profiling in tumor microenvironment was analyzed by flow cytometry post-treatment. The lead compounds, SH-315 (γ IC50110.4nM, δ IC50>10000nM, β IC50>10000nM, α IC503212nM) and SH-327(γ IC50297.4nM, δ IC50>10000nM, β IC50 >10000nM, α IC502438nM), demonstrated significantly higher selectivity for PI3Kγ compared to IPI-549 (γ IC50 5.5nM, δ IC50 968.8nM, β IC50 1566nM, α IC50 1248nM). Concentrations of SH-315 and SH-327 were higher in target tissues (tumors, spleen, TDLNs), while plasma levels were lower than IPI-549, potentially reducing PI3K inhibitor-related side effects. In MMTV-PyMT model, SH-327 and SH-315 at 20 mg/kg, combined with PTX and aPD-1, led to significantly smaller tumors compared to IPI-549. In MC38 model, SH-315 at 10mg/kg combined with PTX and aPD-1 achieved Complete Response (CR) in 60% mice, where SH-327 at 20mg/kg achieved CR in 75% mice. SH-315 at 10mg/kg decreased CD11b+Ly6C+ myeloid-derived suppressor cells (MDSCs) in MC38 tumor by 24% compared to IPI-549 and increased CD8+ T cells in tumor by 41% than IPI-549, suggesting enhanced immune activation and reduced immunosuppression. The PI3Kγ inhibitors SH-315 and SH-327 demonstrated superior anti-tumor efficacy compared to IPI-549. Treatment with SH-315 and SH-327 reduced immunosuppressive MDSCs and increased cytotoxic CD8+ T cell activity, highlighting their potential to drive anti-tumor responses through targeted immune modulation and supporting their further development for cancer immunotherapy. Hanning Wen, Shuai Mao, Mahamadou Djibo, Chengyi Li, Jinsong Tao, Hongyi Zhao, Qiyan Wang, Weijia Zheng, Bo Wen, Wei Gao, Duxin Sun. Highly selective and oral bioavailable PI3Kγ inhibitor for cancer immunotherapy by targeting myeloid-derived suppressor cells in tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3001.

Tumor-associated immunosuppressive neutrophils, termed myeloid-derived suppressor cells (MDSCs), compromise cancer immunotherapy. They can be pathologically programmed as early the hematopoietic stem and progenitor cell (HSPC) stage by suppressing interferon signaling. Reprogramming HSPCs toward antitumor neutrophils through the stimulator of interferon genes (STING) activation offers a promising therapeutic strategy. Here, we demonstrate that an albumin-STING nanoagonist (Nano ZSA-51D) reprograms HSPCs to generate antitumor neutrophils, enhancing MHC I-mediated CD8⁺ T cell immunity. Nano ZSA-51D activates STING–interferon signaling in HSPCs, promoting their expansion and differentiation toward granulocyte-monocyte progenitors via STING-NF-κB-IL-6 signaling. It further reprograms neutrophils into CD14⁺ICAM-1+ subset through STING-NF-κB–TNF-α signaling, enhancing tumor infiltration. These neutrophils upregulate interferon signaling and MHC I antigen presentation, boosting tumor-specific CD8⁺ T cell responses. Adoptive transfer of Nano ZSA-51D-reprogrammed neutrophils with α-PD1 therapy achieves complete colon tumor remission. Our findings provide a novel strategy to reprogram HSPCs toward antitumor neutrophils and highlight the potential of early interventions at HSPC stage to rewire neutrophil fate for cancer immunotherapy. ### Competing Interest Statement The authors have declared no competing interest.

Current cancer vaccines using T cell epitopes activate antitumor T cell immunity through dendritic cell/macrophage-mediated antigen presentation, but they lack the ability to promote B/CD4 T cell crosstalk, limiting their anticancer efficacy. We developed antigen-clustered nanovaccine (ACNVax) to achieve long-term tumor remission by promoting B/CD4 T cell crosstalk. The topographic features of ACNVax were achieved using an iron nanoparticle core attached with an optimal number of gold nanoparticles, where the clusters of HER2 B/CD4 T cell epitopes were conjugated on the gold surface with an optimal intercluster distance of 5-10 nm. ACNVax effectively trafficked to lymph nodes and cross-linked with BCR, which are essential for stimulating B cell antigen presentation-mediated B/CD4 T cell crosstalk in vitro and in vivo. ACNVax, combined with anti-PD-1, achieved long-term tumor remission (>200 days) with 80% complete response in mice with HER2+ breast cancer. ACNVax not only remodeled the tumor immune microenvironment but also induced a long-term immune memory, as evidenced by complete rejection of tumor rechallenge and a high level of antigen-specific memory B, CD4, and CD8 cells in mice (>200 days). This study provides a cancer vaccine design strategy, using B/CD4 T cell epitopes in an antigen clustered topography, to achieve long-term durable anticancer efficacy through promoting B/CD4 T cell crosstalk.

Abstract Background: Stimulator of interferon genes (STING), a dimeric transmembrane adapter protein, plays a pivotal role in regulating tumor immune microenvironment and has been explored as a therapeutic strategy against tumors. Most STING agonists were tested in clinical trials using intratumoral injection with limited systemic efficacy. Several systemically administered STING agonists have progressed to clinical trials, with their efficacy yet to be determined, while their systemic toxicity may limit their application. Our study aimed to develop a novel systemically administrated non-nucleotide STING agonist formulated within albumin nanoparticles, demonstrating potent antitumor activity and low systemic toxicity. Methods & Results: We synthesized a novel non-nucleotide small molecule STING dimer ZSA-51D. The acid form of ZSA-51D exhibited a high binding affinity (EC 50: 1.3 nM) to human STING. ZSA-51D demonstrated potent STING activation in THP1-BlueTM ISG cells, with an EC50 of 5.1 nM. To enable systemic delivery, ZSA-51D was encapsulated in albumin nanoparticles (nano ZSA-51D) with a particle size of 115 nm. Surprisingly, nano ZSA-51D exhibited a tenfold increase in STING activation (EC50 of 0.44 nM) compared to free ZSA-51D. Furthermore, nano ZSA-51D demonstrated sevenfold greater activation of bone marrow-derived dendritic cells (EC 50 of 3.5 nM), and eightfold enhanced repolarization of bone marrow-derived macrophages (EC 50 of 4.2 nM) from M2 to M1 compared to free ZSA-51D. The in-vivo anticancer efficacy was evaluated on MC-38 and KPC 6620 xenograft in C57BL/6 mice using intravenous administration of ZSA-51D (1 mg/kg) or nano ZSA-51D, in combination with PD-1 antibody (α-PD1, 100 μg) for 5 dose every 3 days. The results revealed that nano ZSA-51D exhibited superior anticancer effects compared to free ZSA-51D. Remarkedly, nano ZSA-51D, in combination with α-PD1, completely eradicated cancer in the MC-38 xenograft model. These cured mice completely rejected the rechallenge with MC38 cells 120 days after the initial tumor inoculation, indicating potent and long-term anticancer immune memory for anticancer activity. In addition, we performed the toxicity evaluation of nano ZSA-51D and free ZSA-51D at the same dose regime as the efficacy study. Nano ZSA-51D shows no hematological and liver toxicity. However, free ZSA-51D has a sever local inflammation after injections, whereas nano ZSA-51D has no local toxicity. Conclusion: In this study, we developed a novel systemically administered non-nucleotide sting agonist formulated within albumin nanoparticles. Nano ZSA-51, in combination with α-PD1, demonstrated superior anticancer efficacy and low toxicity, holding the potential for future clinical trials. The significantly enhanced STING activation and in vivo efficacy of nano ZSA-51D warrant further investigation into its underlying mechanisms. Citation Format: Jinsong Tao, Hongyi Zhao, Zhongwei Liu, Hanning Wen, Chengyi Li, Qiuxia Li, Miao He, Bo Wen, Wei Gao, Duxin Sun. A systemically administered non-nucleotide STING agonist in albumin nanoformulation with potent antitumor activity and low toxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6735.

Abstract Pancreatic cancer is the most lethal form of cancer with a 5-year survival at 11% and lacks treatment options. Immunotherapy, specifically anti-PD-1/PD-L1 antibody, proves ineffective for pancreatic cancer patients due to the immunosuppressive tumor microenvironment (TME). STING agonist has emerged as the most effective immune modulator to regulate immunosuppressive TME to enhance the efficacy of immunotherapy across many different cancer types. However, two challenges hinder the use of STING agonist in pancreatic cancer: (A) STING agonist strongly stimulates induction of B regulatory cells (Bregs) in pancreatic tumor and lymph node, leading to an intrinsic resistance to STING agonist and a severe compromised efficacy. (B) Most STING agonists are used by local intra-tumor injection in clinical trials, which only shrinks the local tumors without inhibiting distal tumors or metastasis, whereas it is also not feasible for intra-tumor injection for pancreatic cancer in clinical trials. In response, we developed a first-in-class dual functional drug (SH-273) to overcome STING resistance by eliminating Bregs in both tumors and lymph nodes for long-term efficacy in pancreatic cancer. SH-273 has dual function to stimulates STING function (EC50 100 nM) and inhibits PI3Kγ (IC50 7 nM) that eliminate Bregs to overcome STING resistance. Interestingly, SH-273 achieved dual function with an opposite mechanism in regulating IRF3 phosphorylation in myeloid cells (increase) vs. in Bregs (decrease). In addition, we developed an albumin nanoparticle of SH-273 (Nano-273) for systemic delivery to enhance drug targeting to tumor and lymph node to activate systemic anticancer immunity. 3D imaging results indicated that albumin nano formulation greatly enhanced drug lymphoid draining and pancreatic tumor penetrating. Nano-273, combined with anti-PD-1, achieved long-term median survival of 200 days in LSL-KrasG12D; LSL-Trp53R172H/+; Pdx1cre/+ (KPC) mice (a substantial 67% increase from 120 days without treatment). The 80-day survival extension is significant as KPC mice mimic human pancreatic cancers with Kras/P53 mutations that are unresponsive to other available therapies. Single cell RNA-sequencing and flow cytometry revealed that Nano-273, combined with anti-PD-1, reduces Bregs by 5 to 7-fold while increasing other B cell subtypes by 4-fold in both pancreatic tumors and lymph nodes, compared to control group or group treated with STING agonist alone. These findings suggest that Nano-273 overcomes STING resistance by eliminating Bregs and induced systemic immunity to achieve long-term anti-tumor efficacy in pancreatic cancer. Citation Format: Chengyi Li, Shuai Mao, Hongyi Zhao, Djibo Mahamadou, Zhongwei Liu, Hanning Wen, Miao He, Meilin Wang, Jinsong Tao, Bo Wen, Trang Hoang, Binyamin Jacobovitz, Fei Wen, Wei Gao, Duxin Sun. Overcoming B regulatory cell induced STING resistance by dual functional albumin nanomedicine to prolong survival of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6534.

The immune suppression in tumors and lymph nodes of pancreatic ductal adenocarcinoma (PDAC), regulated by suppressive myeloid cells and regulatory B (Breg) cells, hinders the effectiveness of immunotherapy. Although STING agonists activate myeloid cells to overcome immune suppression, it expands Breg cells, conferring STING resistance in PDAC. We discovered that blocking PI3Kγ during STING activation abolished IRF3 phosphorylation to eliminate Breg cells, while PI3Kγ inhibition sustained STING-induced IRF3 phosphorylation to preserve STING function in myeloid cells. Therefore, we developed a dual functional compound SH-273 and its albumin nanoformulation Nano-273, which stimulates STING to activate myeloid cells and inhibits PI3Kγ to eliminates Breg cells overcoming STING resistance. Nano-273 achieved systemic antitumor immunity through intravenous administration, which decreases Breg cells and remodels microenvironment in tumors and lymph nodes. Nano-273, combined with anti-PD-1, extended median survival to 200 days in transgenic KPC PDAC mice (KrasG12D-P53R172H-Cre), offering potential for PDAC treatment.

In this study, we integrated machine learning (ML), structure-tissue selectivity-activity-relationship (STAR), and wet lab synthesis/testing to design a gastrointestinal (GI) locally activating JAK inhibitor for ulcerative colitis treatment. The JAK inhibitor achieves site-specific efficacy through high local GI tissue selectivity while minimizing the requirement for JAK isoform specificity to reduce systemic toxicity. We used the ML model (CoGT) to classify whether the designed compounds were inhibitors or noninhibitors. Then we used the regression ML model (MTATFP) to predict their IC50 against related JAK isoforms of predicted JAK inhibitors. The ML model predicted MMT3-72, which was retained in the GI tract, to be a weak JAK1 inhibitor, while MMT3-72-M2, which accumulated in only GI tissues, was predicted to be an inhibitor of JAK1/2 and TYK2. ML docking methods were applied to simulate their docking poses in JAK isoforms. Application of these ML models enabled us to limit our synthetic efforts to MMT3-72 and MMT3-72-M2 for subsequent wet lab testing. The kinase assay confirmed MMT3-72 weakly inhibited JAK1, and MMT3-72-M2 inhibited JAK1/2 and TYK2. We found that MMT3-72 accumulated in the GI lumen, but not in GI tissue or plasma, but released MMT3-72-M2 accumulated in colon tissue with minimal exposure in the plasma. MMT3-72 achieved superior efficacy and reduced p-STAT3 in DSS-induced colitis. Overall, the integration of ML, the structure-tissue selectivity-activity-relationship system, and wet lab synthesis/testing could minimize the effort in the optimization of a JAK inhibitor to treat colitis. This site-specific inhibitor reduces systemic toxicity by minimizing the need for JAK isoform specificity.

Immunomodulators that remodel the tumor immunosuppressive microenvironment have been combined with anti-programmed death 1 (α-PD1) or anti-programmed death ligand 1 (α-PDL1) immunotherapy but have shown limited success in clinical trials. However, therapeutic strategies to modulate the immunosuppressive microenvironment of lymph nodes have been largely overlooked. Here, we designed an albumin nanoparticle, Nano-PI, containing the immunomodulators PI3Kγ inhibitor (IPI-549) and paclitaxel (PTX). We treated two breast cancer mouse models with Nano-PI in combination with α-PD1, which remodeled the tumor microenvironment in both lymph nodes and tumors. This combination achieved long-term tumor remission in mouse models and eliminated lung metastases. PTX combined with IPI-549 enabled the formation of a stable nanoparticle and enhanced the repolarization of M2 to M1 macrophages. Nano-PI not only enhanced the delivery of both immunomodulators to lymph nodes and tumors but also improved the drug accumulation in the macrophages of these two tissues. Immune cell profiling revealed that the combination of Nano-PI with α-PD1 remodeled the immune microenvironment by polarizing M2 to M1 macrophages, increasing CD4+ and CD8+ T cells, B cells, and dendritic cells, decreasing regulatory T cells, and preventing T cell exhaustion. Our data suggest that Nano-PI in combination with α-PD1 modulates the immune microenvironment in both lymph nodes and tumors to achieve long-term remission in mice with metastatic breast cancer, and represents a promising candidate for future clinical trials.

With the increase of global cancer morbidity and mortality, it is of great importance to control the development of cancer. In recent years, plenty of strategies have been developed for tumor diagnosis and therapy. As one of the major approaches, ligand-mediated receptor-introduced drug delivery has been extensively studied over the past decade. Our laboratory mainly engages in the related researches on the combined diagnosis and treatment of tumors, especially glioma. A series of smart biocompatible theranostic systems were designed and constructed, including precise oligomer-based nanoparticles, polymer-coated nitrogen carbon nanodots, multifunctional mesoporous silica graphite nanosheets, magnetic graphene mesoporous silica nanoparticles, etc. Then, based on the design of specific ligand-receptor targeting strategies such as IL-13, Angiopep and I6P7, these systems were applied for tumor-targeted drug delivery, gene therapy, photothermal therapy and tumor imaging. For example, the nuclear localization signal sequence LNP in Lim kinase 2 protein, was used to modify the dendrimer-based nano gene delivery system. With the ability to cross the blood-brain barrier, the translocation efficiency of nanoparticles and anti-glioma effect were improved. And, the new controlled drug delivery system, using graphene as nanocarrier, was prepared with excellent properties, such as pHand NIRresponsive, and controlled drug release, showing chemotherapeutic and photothermal synergistic therapy of glioma. A receptor-mediated cascade-targeting drug delivery system, which constructed by polymer-coated nitrogen-carbon nanodots and a multifunctional peptide (I6P7) with the ability to transport through the blood-brain barrier, target glioma and inhibit the expression of tumor growth factors, were constructed for the imaging-guided combined glioma therapy. Relating work provides new ideas and theoretical basis for cancer theragnosis.

Glioma has been considered to be the most frequent primary tumor within central nervous system (CNS). The complexity of glioma, especially the existence of blood-brain barrier (BBB), makes the survival and prognosis of glioma remain poor even after a standard treatment based on the standard therapy (surgery combined with radiotherapy or chemotherapy). This provides a rationale for the development of some novel therapeutic strategies. Among them, receptor-mediated drug delivery is a specific pattern taking advantage of differential expression of receptors between tumors and normal tissues. The strategy can actively transport drugs such as small molecular drugs, gene medicines, and therapeutic proteins to glioma while minimizing adverse reactions. Besides, adsorptive-mediated, transporter-mediated process, or nasal pathway are also widely studied strategies. This review will summarize recent progresses on glioma targeted drug delivery systems based on several main mechanisms and conclude the challenges and prospects of these glioma targeted systems for future applications.