InVivoMAb human IgG1 isotype control

DF6215 is a rationally engineered interleukin-2 (IL-2) Fc-fusion protein developed to overcome efficacy and safety limitations of traditional IL-2 cancer immunotherapy. Unlike non-alpha (non-α) IL-2 variants that eliminate CD25 binding and underperform clinically, DF6215 retains moderate IL-2 receptor α (IL-2Rα) affinity while enhancing IL-2Rβγ signaling and extending the half-life via an engineered immunoglobulin (Ig)G1 Fc domain. This design preferentially expands cytotoxic CD8+ T cells and natural killer cells over regulatory T cells, resulting in favorable effector-to-regulatory cell ratios, enhanced immune activation, and robust tumor regression in mouse models. In poorly immunogenic tumors, DF6215 synergized with PD-1 blockade to achieve durable responses without added toxicity. Cynomolgus monkey studies confirm DF6215's pharmacodynamics and favorable safety profile, with no signs of vascular leak syndrome or cytokine release syndrome. These findings position DF6215 as a differentiated IL-2 capable of modulating the tumor microenvironment and achieving potent anti-tumor immunity with improved tolerability, supporting its advancement into clinical trials for solid tumors.

Ewing sarcoma is a rare and aggressive cancer of the bone and soft tissues primarily affecting children and young adults. Prognosis for patients with metastatic or recurrent disease remains poor despite intensive multimodal therapy, highlighting the need of novel therapeutic approaches. The disialoganglioside GD2 is highly expressed on Ewing sarcoma cells, making this tumor eligible for anti-GD2 immunotherapy with dinutuximab beta. Through in vitro and in vivo approaches, this study demonstrated that dinutuximab beta effectively suppressed tumor growth by 60% (p = 0.0135) and improved survival rate by 68% (p = 0.0006) in a mouse model xenograft. The combination therapy with doxorubicin demonstrated superior efficacy compared to monotherapy, with enhanced tumor suppression (86%; p = 0.0009) and an extension of survival rate (146%; p = 0.000025). This study showed that dinutuximab beta, particularly in combination with standard chemotherapy, offers a promising approach to improve outcomes for high-risk Ewing sarcoma patients, providing a more effective alternative to current treatments.

The pituitary adenylate cyclase-activating polypeptide type I receptor (PAC1R) is a class B G protein-coupled receptor implicated in a variety of physiological and pathological processes, including cancer. While PAC1R has been reported to act as either an oncogene or a tumor suppressor in a context-dependent manner, its role in neuroblastoma remains largely unexplored. In this study, we identify PAC1R as being selectively overexpressed in neuroblastoma and strongly associated with poor patient prognosis, supporting its potential as a prognostic biomarker. Functionally, PAC1R activation by PACAP38 promoted neuroblastoma cell proliferation and migration through distinct G protein signaling pathways. Pharmacological inhibition and CRISPR/Cas9-mediated gene knockout revealed that proliferation is mediated by the Gαs/EPAC/AKT-ERK axis, whereas migration requires cooperative signaling through Gα12/13- and Gαq-dependent activation of the RhoA-ROCK pathway. Comprehensive signaling analyses using TRUPATH and BRET-based biosensors demonstrated broad activation of Gαs, Gαq/11, and Gα13 by PACAP38 and PACAP27, while maxadilan and VIP displayed biased agonism toward Gαs and Gα15. β-Arrestin recruitment assays further showed that PACAP38 exhibits greater potency and efficacy than PACAP27. Among three PAC1R inhibitors tested, AMG-301, a clinical-stage monoclonal antibody, most effectively inhibited PAC1R-mediated G protein activation, calcium mobilization, RhoA signaling, proliferation, and migration. Together, these findings establish PAC1R as a functionally significant and druggable target in neuroblastoma, highlight its context-dependent signaling plasticity, and support the rationale for PAC1R-targeted therapeutic strategies in high-risk neuroblastoma.

The human respiratory syncytial virus (hRSV) is a pathogen of global concern, causing significant morbidity and mortality, mainly in preterm infants. To date, all licenced monoclonal antibodies (mAbs) developed against hRSV have targeted its surface fusion or pre-fusion protein (F-hRSV).

Immune-driven fibrotic skin diseases, including scleroderma/systemic sclerosis (SSc) and chronic graft-versus-host disease (GVHD), cause skin stiffening that has a major impact on patient quality of life and associated patient mortality. Therapies to improve sclerotic skin resulting from these diseases are largely ineffective. We previously showed that epiregulin (EREG), a dendritic cell type 3-derived epidermal growth factor receptor (EGFR) ligand, is elevated in the skin and lungs of patients with SSc and required for the maintenance of skin fibrosis. Here, we developed a fully human anti-EREG neutralizing antibody that has both high affinity and specificity. We found this therapeutic antibody to be functional and safe in vivo using human EREG knockin mice. To understand the antifibrotic mechanism of targeting EREG, we aligned skin single-cell transcriptomic profiles of SSc, morphea (localized scleroderma), and sclerotic GVHD (SclGVHD) with disease biomarkers. EREG expression in the skin was elevated in all 3 fibrotic diseases and is a driver of tenascin C (TNC) production by myofibroblasts. TNC is a proinflammatory extracellular glycoprotein that functions as an endogenous Toll-like receptor 4 (TLR4) ligand, which induces expression of TLR4 target genes CCL2 and interleukin-6. Examination of skin explants from patients with active SclGVHD treated with anti-EREG therapeutic antibody by spatial transcriptomics demonstrated upregulation of matrix degradation by increased MMP and decreased TIMP1 expression. Protein measurements showed reduced secretion of EREG targets TNC, CCL2, and TIMP1 in all patients and type I collagen and FN1 in three-fourths of patients. Thus, sclerotic skin treated with the anti-EREG therapeutic antibody reduced inflammatory and fibrosis biomarkers associated with EGFR and TLR4 signaling.

Polatuzumab vedotin (pola) is a CD79B-targeting antibody-drug conjugate with significant clinical activity in systemic diffuse large B-cell lymphoma. However, the ability of pola to penetrate the blood-brain barrier (BBB) and induce responses in central nervous system (CNS) lymphoma (CNSL) is unknown. Since other antibody-based therapies can partially penetrate the BBB to induce clinical responses in CNSL and other CNS malignancies, we hypothesized that pola would also partially penetrate the BBB, which could support its evaluation in future CNSL clinical trials. To test this hypothesis, we first evaluated the preclinical efficacy of pola in primary and secondary CNSL xenografts, where we observed that pola significantly decreased CNS tumor burden and prolonged survival in mice. To extend these findings, we compiled a clinical case series of 3 patients with CNSL treated with pola-based treatment. Here, on-treatment cerebrospinal fluid (CSF) samples revealed pola CSF drug concentrations exceeding its established 50% inhibitory concentration, with CSF drug levels being 0.56% to 1.31% of those in plasma. Interestingly, 2 of the 3 patients with CNSL achieved a complete response to pola-based treatment. In summary, these data indicate pola is effective against preclinical CNSL models and can partially penetrate the BBB in patients with CNSL, which together provide support for the evaluation of pola-based treatment in future clinical trials of primary and secondary CNSL.

SIRPG, a primate-specific type 1 transmembrane protein in the Signal Regulatory Protein (SIRP) family, is predominantly expressed in T cells. It contains a short cytoplasmic domain, which does not contain any known signaling motif, and its only known ligand is CD47. Several genetic variations in SIRPG, including the V263A (rs6043409) polymorphism, linked to increased type 1 diabetes risk, highlight its potential importance. However, its expression and physiological role remain largely unclear due to its absence in rodents. Here, we demonstrate that SIRPG and GzmB exhibit near mutually exclusive expression in resting peripheral CD8+ T cells. We further show that SIRPG serves as a valuable marker for GzmK-expressing CD8+ T cells in peripheral blood and that its expression in both CD4+ and CD8+ T cells is upregulated by anti-CD3 stimulation, with further enhancement by the TNFα inhibitor adalimumab, but not certolizumab. While SIRPG ablation minimally affects T cell activation and IFNγ/TNFα production, it impairs the expression of mitosis-regulating genes like UBE2C and TOP2A, leading to reduced proliferation, and alters the expression of certain activation-induced surface molecules, including CRTAM. Notably, SIRPG-mediated proliferation and CRTAM expression are cell-autonomous and CD47-independent. Structural and functional analyses reveal that SIRPG-driven proliferation is independent of its extracellular D1 domain, not significantly affected by the V263 variant, but dependent on its cytoplasmic domain. Collectively, our findings offer novel insights into the expression, function, and mechanism of action of SIRPG in T cells.

Immune checkpoint blockade (ICB) therapy, especially in combination regimens, has significantly increased survival of renal cell carcinoma (RCC) patients. However, the ICB-resistant mechanisms remain largely unclear and require further investigation. Here, an immunosuppressive ecosystem in ICB-resistant tumors is identified, featured by preferential infiltration of MARCO+ tumor-associated macrophages (TAMs) and restrained cytotoxicity of CD8+ cytotoxic T lymphocytes (CTLs). The infiltrated MARCO+ TAMs can obstruct the development of CD8+ CTLs by impairing MHC-I-mediated neoantigen cross-presentation. Mechanistically, MARCO up-regulates the expression of SOCS1, which obstructs the kinase activity of JAK1, thereby downregulating MHC-I expression through the inhibition of the JAK1-STAT1-NLRC5 signaling cascade. Further, MARCO blockade significantly facilitates ICB therapy in in vivo models by recovering tumor recognition and priming anti-tumor CD8+ T cell responses. Taken together, these findings highlight MARCO as a highly desirable target in ICB-refractory individuals for immunorecognition reignition and immunotherapy modulation.

Cancer metastasis to sentinel lymph nodes (LNs) is often the first marker of potential disease progression. Although it is recognized that tumor-induced lymphangiogenesis facilitates metastasis into LNs in murine models, tumor-induced alterations in human lymphatic vessels remain obscure. Here we use single-cell RNA sequencing and high-resolution spatial transcriptomics to profile lymphatic endothelial cell (LEC) subsets in paired metastatic and non-metastatic LNs obtained from female patients with treatment-naïve breast cancer. Tumor metastasis decreases immunoregulatory LEC subsets, such as PD-L1+ subcapsular sinus LECs, while inducing an increase in capillary-like CD200+ HEY1+ LECs. Matrix Gla protein (MGP) is the most upregulated gene in metastatic LN LECs, and its expression on LECs is TGF-β and VEGF dependent. Upregulated MGP promotes cancer cell adhesion to LN lymphatics. Thus, breast cancer cell metastasis to LNs remodels LEC subsets in human LNs and escalates MGP expression, potentially facilitating cancer cell dissemination through the lymphatic system.

Immune checkpoint inhibitors (ICI) benefit some cancer patients but de novo resistance remains poorly understood. Analyzing transcriptional data from two clinical trial cohorts, GO30140 and IMbrave150, we find B cell lymphoma 9 (BCL9), a Wnt/β-catenin co-factor, associated with resistance. We develop a BCL9-targeting peptide, hsBCL9Z96, which suppresses tumor growth in combination with anti-PD-L1 ab in preclinical hepatocellular carcinoma (HCC) mouse models. Multi-omics analyses implicate targeting BCL9 inhibits BMP4 secretion and downregulates CD24 on tumor cells, reprogramming macrophages toward a tumor-suppressive phenotype and promoting macrophage phagocytosis. This in turn rejuvenates T cell immunity via enhanced macrophage-mediated antigen presentation. Our data extend our understanding of how tumor-derived Wnt/β-catenin signaling impedes the innate and adaptive immune responses in the tumor microenvironment and provide preliminary evidence that targeting BCL9 is a promising preclinical strategy to mitigate ICI resistance in HCC.

CD16a triggers antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis by natural killer (NK) cells and macrophages in anti-tumor immunity. However, CD16a undergoes cleavage by ADAM17 that dampens its anti-tumor immunity. We here develop a monoclonal antibody (F9H4) that binds to CD16a and inhibits its cleavage. F9H4 retains CD16a on the surface of NK cells and macrophages, without triggering or blocking CD16a. F9H4 also binds to and inhibits shedding of CD16b by neutrophils, and inhibits CD16a/b shedding by leukocytes in tumor samples from lung cancer patients. F9H4 promotes ADCC against lung cancer cells that are opsonized by cetuximab, an epidermal growth factor receptor antibody that engages CD16a. F9H4 synergizes with cetuximab to inhibit human lung adenocarcinoma development in immunodeficient mice reconstituted with human NK cells. F9H4 combining with cetuximab also inhibits murine lung carcinoma growth in Fc gamma receptor-humanized mice, and such effect is mediated by NK cells and macrophages. The efficacy of F9H4+cetuximab in lung cancer models is the proof-of-concept for this new approach that promotes anti-tumor functions of Fc-enabled antibodies.

Durable serological protection is maintained through the persistence of antigen-specific plasma cells (PCs), but key factors regulating the survival of nascent PCs remain unclear. Previously, we reported that bone marrow (BM) PCs partially organize into clusters that are enriched for long-lived PCs, suggesting that clusters are survival niches. Here, we report that acute blockade of a proliferation-inducing ligand (APRIL) and B cell activating factor (BAFF) using transmembrane activator and CAML interactor (TACI)-Fc rapidly disrupts clusters and mobilizes BM PCs. CD138, a surface co-receptor that is abundant on PCs and binds APRIL but not BAFF, regulates PC retention in the BM and adhesion and motility on fibronectin. Cell-intrinsic CD138 levels control competition for survival between nascent CD138low PCs and mature CD138high PCs, and enhanced survival of CD138high PCs correlates with retention in clusters. Collectively, these results indicate that PC clusters are survival niches and that dynamic competition between new and pre-existing PCs regulates the survival of new PCs and the durability of antibody responses.

Regulatory T cells (Tregs) are essential for maintaining immune balance by controlling the activation and expansion of other immune cells. Conventional suppression assays often rely on co-culturing purified cell populations, which limits multiplexed phenotyping and physiological relevance. This protocol describes a high-dimensional, single-cell assay for profiling Treg-mediated suppression within a peripheral blood mononuclear cell (PBMC) system. Tregs are first isolated by cell sorting and then reintroduced into autologous PBMCs at defined ratios. A 52-marker mass cytometry (CyTOF) panel is used to quantify cell division and phenotypic responses across multiple immune subsets. This approach allows for integrated analysis of Treg function with broad compatibility for patient profiling and drug evaluation. Key features • Quantifies Treg-mediated suppression in autologous PBMCs at single-cell resolution. • Enables high-dimensional phenotyping and proliferation tracking across multiple immune subsets using a 52-marker CyTOF panel. • Maintains physiological relevance by assessing suppression in a complex PBMC environment. • Compatible with patient-derived samples and drug perturbation experiments for translational immunology applications.

Gallbladder cancer (GBC) is the most common malignancy in the biliary system and lacks biomarkers for personalized therapy. Here, we reported that hepatic leukemia factor (HLF) was highly expressed in gallbladder cancer stem cells (CSCs) and patients with gemcitabine-resistant GBC. Mechanistic study revealed that interleukin-6 receptor (IL-6R) and transcription factor EB (TFEB) are direct target genes of HLF. The IL-6/IL-6R/signal transducer and activator of transcription 3 axis transactivates HLF expression in GBC, forming a positive feedback loop. Functional studies revealed that HLF promoted gallbladder CSCs' expansion and gemcitabine resistance via TFEB-induced autophagy. In addition, HLF drives TFEB-induced programmed death ligand 1 expression in human tumors and governs tumor immune evasion in a CD8+ T cell-dependent manner. Patient cohorts' analysis suggested that HLF levels in GBCs might determine the distinct responses to chemotherapy and immunotherapy. In conclusion, our findings demonstrated that HLF could act as a driver for gallbladder CSCs' self-renewal and drug resistance and a biomarker for individualized therapy.

Macrophages infiltrate solid tumors and either support survival or induce cancer cell death through phagocytosis or cytotoxicity. To uncover regulators of macrophage cytotoxicity towards cancer cells, we perform two co-culture CRISPR screens using CAR-macrophages targeting different tumor associated antigens. Both identify ATG9A as an important regulator of this cytotoxic activity. In vitro and in vivo, ATG9A depletion in cancer cells sensitizes them to macrophage-mediated killing. Proteomic and lipidomic analyses reveal that ATG9A deficiency impairs the cancer cell response to macrophage-induced plasma membrane damage through defective lysosomal exocytosis, reduced ceramide production, and disrupted caveolar endocytosis. Depleting non-cytotoxic macrophages using CSF1R inhibition while preventing ATG9A-mediated tumor membrane repair enhances the anti-tumor activity of therapeutic antibodies in mice. Thus, macrophage cytotoxicity plays an important role in tumor elimination during antibody or CAR-macrophage treatment, and inhibiting tumor membrane repair via ATG9A, particularly in combination with cytotoxic macrophage enrichment through CSF1R inhibition, improves tumor-targeting macrophage efficacy.

Dengue is a mosquito-borne virus infection affecting half of the world's population for which therapies are lacking. The role of T and NK-cells in protection/immunopathogenesis remains unclear for dengue. We performed a longitudinal phenotypic, functional and transcriptional analyses of T and NK-cells in 124 dengue patients using flow cytometry and single-cell RNA-sequencing. We show that T/NK-cell signatures early in infection discriminate patients who develop severe dengue (SD) from those who do not. These signatures are exacerbated in patients with overweight/obesity compared to healthy weight patients, supporting their increased susceptibility to SD. In SD, CD4+/CD8+ T-cells and NK-cells display increased co-inhibitory receptor expression and decreased cytotoxic potential compared to non-SD. Using transcriptional and proteomics approaches we show decreased type-I Interferon responses in SD, suggesting defective innate immunity may underlie NK/T-cell dysfunction. We propose that dysfunctional T and NK-cell signatures underpin dengue pathogenesis and may represent novel targets for immunomodulatory therapy in dengue.

The N6-methyladenosine (m6A) methylase WTAP has been identified as a proto-oncogene in multiple cancers, including hepatocellular carcinoma (HCC). Interestingly, although WTAP expression does not differ between normal liver and HCC tissues or across different stages of HCC, patients with higher WTAP expression exhibit significantly shorter median survival times (MSTs). Here, we found that WTAP was upregulated in tumor-infiltrating CD8+ T cells, which were more enriched in HCC patients compared to the controls. HCC patients also displayed higher PD1 levels and a greater proportion of exhausted CD8+ T cells (TCF+ PD1+). Moreover, WTAP promoted PD1 expression and suppressed the proliferation and immune activity of CD8+ T cells. In the co-culture system, WTAP-overexpressing CD8+ T cells enhanced the malignancy of HCC cells. Notably, WTAP silencing further augmented the boosting effect of PD1 silencing on CD8+ T cell immune activity and strengthened its inhibitory effect on HCC cell growth. As an m6A "writer", WTAP increased the m6A level of PD1 mRNA, thereby promoting YTHDF1-mediated translation of PD1. Finally, in the HuNSG xenograft tumor model, WTAP knockdown not only alleviated CD8+ T cell exhaustion and inhibited tumor progression but also synergistically enhanced the antitumor efficacy of anti-PD1 therapy. In conclusion, WTAP promoted CD8+ T cell exhaustion and HCC progression by facilitating the m6A modification and translation of PD1 mRNA.

The lack of T cells in tumors is a major hurdle to successful immune checkpoint therapy (ICT). Therefore, therapeutic strategies promoting T cell recruitment into tumors are warranted to improve the treatment efficacy. Here, we report that Fc-optimized anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies are potent remodelers of tumor vasculature that increase tumor-associated high endothelial venules (TA-HEVs), specialized blood vessels supporting lymphocyte entry into tumors. Mechanistically, this effect is dependent on the Fc domain of anti-CTLA-4 antibodies and CD4+ T cells and involves interferon gamma (IFNγ). Unexpectedly, we find that the human anti-CTLA-4 antibody ipilimumab fails to increase TA-HEVs in a humanized mouse model. However, increasing its Fc effector function rescues the modulation of TA-HEVs, promotes CD4+ and CD8+ T cell infiltration into tumors, and sensitizes recalcitrant tumors to programmed cell death protein 1 (PD-1) blockade. Our findings suggest that Fc-optimized anti-CTLA-4 antibodies could be used to reprogram tumor vasculature in poorly immunogenic cold tumors and improve the efficacy of ICT.

Tissue regenerative responses involve complex interactions between resident structural and immune cells. Recent reports indicate that accumulation of senescent cells during injury repair contributes to pathological tissue fibrosis. Using tissue-based spatial transcriptomics and proteomics, we identified upregulation of the immune checkpoint protein, cytotoxic T lymphocyte-associated protein 4 (CTLA4), on CD8+ T cells adjacent to regions of active fibrogenesis in human idiopathic pulmonary fibrosis and in a repetitive bleomycin lung injury murine model of persistent fibrosis. In humanized CTLA4-knockin mice, treatment with ipilimumab, an FDA-approved drug that targets CTLA4, resulted in accelerated lung epithelial regeneration and diminished fibrosis from repetitive bleomycin injury. Ipilimumab treatment resulted in the expansion of Cd3e+ T cells, diminished accumulation of senescent cells, and robust expansion of type 2 alveolar epithelial cells, facultative progenitor cells of the alveolar epithelium. Ex vivo activation of isolated CTLA4-expressing CD8+ cells from mice with established fibrosis resulted in enhanced cytolysis of senescent cells, suggesting that impaired immune-mediated clearance of these cells contributes to persistence of lung fibrosis in this murine model. Our studies support the concept that endogenous immune surveillance of senescent cells may be essential in promoting tissue regenerative responses that facilitate the resolution of fibrosis.

The PD-L1/PD-1 pathway is crucial for immune regulation and has become a target in cancer immunotherapy. However, in order to improve patient selection for immune checkpoint blockade (ICB) therapies, better selection criteria are needed. This study explores how the N-glycosylation of PD-L1 affects its interaction with PD-1 and ICB efficacy, focusing on its four N-linked glycosylation sites: N35, N192, N200, and N219.