Costimulatory Pathway Research Articles

OX40 agonism enhances PD-L1 checkpoint blockade by shifting the cytotoxic T cell differentiation spectrum

Immune checkpoint therapy (ICT) has the power to eradicate cancer, but the mechanisms that determine effective therapy-induced immune responses are not fully understood. Here, using high-dimensional single-cell profiling, we interrogate whether the landscape of Tcell states in the peripheral blood predict responses to combinatorial targeting of the OX40 costimulatory and PD-1 inhibitory pathways. Single-cell RNA sequencing and mass cytometry expose systemic and dynamic activation states of therapy-responsive CD4+ and CD8+ Tcells in tumor-bearing mice with expression of distinct natural killer (NK) cell receptors, granzymes, and chemokines/chemokine receptors. Moreover, similar NK cell receptor-expressing CD8+ Tcells are also detected in the blood of immunotherapy-responsive cancer patients. Targeting the NK cell and chemokine receptors in tumor-bearing mice shows the functional importance of these receptors for therapy-induced anti-tumor immunity. These findings provide a better understanding of ICT and highlight the use and targeting of dynamic biomarkers on Tcells to improve cancer immunotherapy.

Tumor Cell Nanovaccines Based on Genetically Engineered Antibody-Anchored Membrane.

Despite the promise in whole-tumor cell vaccines, a key challenge is to overcome the lack of costimulatory signals. Here, agonistic-antibody-boosted tumor cell nanovaccines are reported by genetically engineered antibody-anchored membrane (AAM) technology, capable of effectively activating costimulatory pathways. Specifically, the AAM can be stably constructed following genetic engineering of tumor cell membranes with anti-CD40 single chain variable fragment (scFv), an agonistic antibody to induce costimulatory signals. The nanovaccines are versatilely designed and obtained based on the anti-CD40 scFv-anchored membrane and nanotechnology. Following vaccination, the anti-CD40 scFv-anchored membrane nanovaccine (Nano-AAM/CD40) significantly facilitates dendritic cell maturation in CD40-humanized transgenic mice and subsequent adaptive immune responses. Compared to membrane-based nanovaccines alone, the enhanced antitumor efficacy in both "hot" and "cold" tumor models of the Nano-AAM/CD40 demonstrates the importance of agonistic antibodies in development of tumor-cell-based vaccines. To expand the design of nanovaccines, further incorporation of cell lysates into the Nano-AAM/CD40 to conceptually construct tumor cell-like nanovaccines results in boosted immune responses and improved antitumor efficacy against malignant tumors inoculated into CD40-humanized transgenic mice. Overall, this genetically engineered AAM technology provides a versatile design of nanovaccines by incorporation of tumor-cell-based components and agonistic antibodies of costimulatory immune checkpoints.

Renin-angiotensin-aldosterone system function in the pig-to-baboon kidney xenotransplantation model

After pig-to-baboon kidney transplantation, episodes of hypovolemia and hypotension from an unexplained mechanism have been reported. This study evaluated the renin-angiotensin-aldosterone system post–kidney xenotransplantation. Kidneys from genetically-engineered pigs were transplanted into 5 immunosuppressed baboons after the excision of the native kidneys. Immunosuppressive therapy was based on the blockade of the CD40/CD154 costimulation pathway. Plasma renin, angiotensinogen (AGT), angiotensin II (Ang II), aldosterone levels, and urine osmolality and electrolytes were measured in healthy pigs, healthy nonimmunosuppressed baboons, and immunosuppressed baboons with life-supporting pig kidney grafts. After pig kidney transplantation, plasma renin and Ang II levels were not significantly different, although Ang II trended lower, even though plasma AGT and potassium were increased. Plasma aldosterone levels were unchanged. Urine osmolality and sodium concentration were decreased. Even in the presence of increasing AGT and potassium levels, lower plasma Ang II concentrations may be because of reduced, albeit not absent, the reactivity of pig renin to cleave baboon AGT, suggesting an impaired response of the renin-angiotensin-aldosterone system to hypovolemic and hypotensive episodes. The maintenance of aldosterone may be protective. The reduced urine osmolality and sodium concentration reflect the decreased ability of the pig kidney to concentrate urine. These considerations should not prohibit successful clinical pig kidney xenotransplantation.

CRC-403: A Phase 1/2 Study of bbT369, a Dual CD79a and CD20 Targeting CAR T Cell Drug Product with a Gene Edit, in Relapsed and/or Refractory B Cell Non-Hodgkin's Lymphoma (NHL)

BACKGROUND: Currently approved CD19 directed CAR T cell therapies have improved outcomes for non-Hodgkin lymphoma (NHL) patients, however only 30-40% of patients treated at 2nd relapse or later obtain long term remission after this treatment (Neelapu et al. 2017; Schuster et al. 2019). A next generation autologous CAR T cell, bbT369, has been devised specifically to address and overcome hypothesized mechanisms of CD19 CAR T cell treatment failure including loss/downregulation of target antigen, loss of co-stimulation pathways on tumor cells, exhaustion of CAR T cells, and CAR T cell dysfunction due to an immunosuppressive microenvironment (Shah and Fry 2019). bbT369 is a dual targeting (CD79a/CD20) CAR T cell that uses an OR gated design (encounter with either antigen activates the CAR T cell) to limit antigen escape. The construct contains split costimulatory domains (CD28 and 41BB) to enhance T cell activation and a gene edit knocking-out CBLB function intended to enhance potency and reduce T cell exhaustion. Studies have demonstrated CD79a and CD20 may be ideal targets in B cell lymphoma, with high tissue restricted expression. In Daudi cell and mouse models, bbT369 outperformed CD19 directed CAR T cells demonstrating increased IL-2 secretion and longer durations of tumor control (Certo et al, 2022). METHODS: CRC-403 (NCT05169489) is a non-randomized, open label, multi-site Phase 1/2 study enrolling relapsed and/or refractory B Cell Non-Hodgkin's Lymphoma (NHL), including diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal (thymic) large B cell lymphoma (PMBCL), follicular lymphoma (FL) 3b, and DLBCL transformed from FL (tFL). Patients must have relapsed after ASCT or after at least 2 prior lines of therapy, including an anti-CD20 monoclonal antibody and an anthracycline containing chemotherapy regimen. Patients with tFL must be relapsed after receipt of ASCT or at least 2 prior therapies after documentation of transformation. In addition to patients naïve to CAR T cell therapy, patients with prior exposure to non-investigational CD19 CAR T cell therapy are eligible for enrollment if they did not experience disease progression within 6 weeks of initial CAR T cell infusion. Approximately 50 patients will be enrolled during the dose escalation phase to ensure a maximum of 36 subjects will be treated with bbT369. The primary endpoint of the phase 1 portion of this study is incidence of safety events, including adverse event, adverse events of special interest and dose limiting toxicities. Secondary endpoints include investigator assessed overall response rate including complete response rate, time to response, time to complete response and time to next therapy for B-NHL. Exploratory endpoints include OS, DOR, PFS, bbT369 expansion kinetics including expansion and persistence, immunophenotype in peripheral blood and tumor biopsy tissue with the objective of correlating findings with clinical response. The starting dose of bbT369 is 50x106 CAR+ T cells and a BOIN design is being used for dose escalation/de-escalation decisions during the study. Upon establishment of the RP2D, the phase 2 portion will begin enrollment.

Identification of cuproptosis-related lncRNAs for prognosis and immunotherapy in glioma.

Glioma is a highly invasive primary brain tumour, making it challenging to accurately predict prognosis for glioma patients. Cuproptosis is a recently discovered cell death attracting significant attention in the tumour field. Whether cuproptosis-related genes have prognostic predictive value has not been clarified. In this study, uni-/multi-variate Cox and Lasso regression analyses were applied to construct a risk model based on cuproptosis-related lncRNAs using TCGA and CGGA cohorts. A nomogram was constructed to quantify individual risk, including clinical and genic characteristics and risk. GO and KEGG analyses were used to define functional enrichment of DEGs. Tumour mutation burden (TMB) and immune checkpoint analyses were performed to evaluate potential responses to ICI therapy. Ten prognostic lncRNAs were obtained from Cox regression. Based on the median risk score, patients were divided into high- and low-risk groups. Either for grade 2-3 or for grade 4, glioma patients with high-risk exhibited significant poorer prognoses. The risk was an independent risk factor associated with overall survival. The high-risk group was functionally associated with immune responses and cancer-related pathways. The high-risk group was associated with higher TMB scores. The expression levels of many immune checkpoints in the high-risk group were significantly higher than those in the low-risk group. Differentiated immune pathways were primarily enriched in the IFN response, immune checkpoint and T-cell co-stimulation pathways. In conclusion, we established a risk model based on cuproptosis-related lncRNAs showing excellent prognostic prediction ability but also indicating the immuno-microenvironment status of glioma.

Elaborating on anti CTLA-4 mechanisms of action using an agent-based modeling approach

Anti CTLA-4 therapy is aimed at blocking the Cytotoxic T-lymphocyte antigen-4 (CTLA-4), a key cancer immunity cycle checkpoint. The mechanism of action of CTLA-4 may be described as a dynamic competition for the B7 ligand which, subsequently, interferes with the CD28-B7 costimulatory pathway. Anti CTLA-4 blockade enhances the process of cognate T cell activation and leads to a broadening of the T cell repertoire. In the present work, we used an agent-based modeling (ABM) platform of T cell immune response development, to explore hypothetical modes of anti CTLA-4 action. The model features a selected number of activated T cell clones, calculated based on combined random and chemotactically-driven encounters with antigen-presenting dendritic cells (DCs) and a distribution of individual T cell affinities to the antigen of interest. The proposed model can be used as a quantitative tool to explore various hypotheses on T cell immunity regulation and validate these against experimental data. A comprehensive ABM model analysis of immune response dynamic simulations revealed several putative anti CTLA-4 mechanisms of action, including: (i) an increase in the probability of primary activation of lymphocytes; (ii) T cell activation enhancement via a prolongation of short contacts with dendritic cells; and (iii) an increase in the maximum level of activation signal (or saturation), accumulated through a series of short contacts with DCs. The modeling work further demonstrates that it is only when considering jointly these various modes of anti CTLA-4 effects on the T cell immune response dynamics that a biologically meaningful increase in both the production of activated cells and the expansion of the T cell repertoire is observed. These model-based results are overall consistent with the collective biological knowledge on the functional role of CTLA-4. Furthermore, the ABM presented here may allow to interrogate various mechanistic scenarios underlying adverse events mediated by anti CTLA-4 pharmacologic therapies.

Antibody based conditioning for allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapeutic option for many patients with hematological malignancies and nonmalignant hematopoietic disorders. To achieve stable engraftment of donor hematopoietic stem cells (HSCs), recipient HSC deletion is needed to create space for incoming donor HSCs and donor HSCs must escape immune rejection by the recipient. Conventional allo-HSCT requires high dose of irradiation and/or chemotherapy to produce sufficient host stem cell and immune system ablation to permit donor HSC engraftment. However, these procedures also result in nonspecific tissue injury that can cause short- and long-term adverse effects as well as incite and amplify graft-versus-host-disease (GVHD). The delivery of targeted radiotherapy to hematopoietic tissues with the use of a radioimmunoconjugate (ROIC) as a part of transplant preparative regimen has shown clinical benefits. ROIC clinical data provide evidence for decreased relapse without increased transplant-related mortality by delivering higher targeted radiation to sites of malignancy than when given in a nontargeted fashion. An alternative approach to allo-HSCT has been developed and tested in preclinical mouse models in which nonmyeloablative preconditioning with low dose of the alkylating agent (busulfan) or lower systemic dose of irradiation combined with co-stimulatory pathway blockade (CTLA4-Ig, anti-CD40L monoclonal antibody) and/or immunosuppressive drugs have been used. Under these conditions, mixed chimerism and transplantation tolerance to fully MHC mismatched donor marrow was observed. Recently, several novel proof-of-concept antibody-mediated preconditioning methods have been developed that can selectively target hematopoietic stem and immune cells with minimal overall toxicity. Antibody-drug-conjugate (ADC) combined with reduced intensity conditioning or high dose ADC as single dose monotherapy have shown promise for allo-HSCT in preclinical models. The purpose of the current review is to discuss the literature exploring antibody-based conditioning that includes native antibody, radiolabeled antibody conjugates, and ADC for allo-HSCT.

New immunosuppressive agents in transplantation

Immunosuppressive agents have enabled the development of allogenic transplantation during the last 40 years, allowing considerable improvement in graft survival. However, several issues remain such as the nephrotoxicity of calcineurin inhibitors, the cornerstone of immunosuppressive regimens and/or the higher risk of opportunistic infections and cancers. Most immunosuppressive agents target T cell activation and may not be efficient enough to prevent allo-immunization in the long term. Finally, antibody mediated rejection due to donor specific antibodies strongly affects allograft survival.Many drugs have been tested in the last decades, but very few have come to clinical use. The most recent one is CTLA4-Ig (belatacept), a costimulation blockade molecule that targets the second signal of T cell activation and is associated with a better long term kidney function than calcineurin inhibitors, despite an increased risk of acute cellular rejection.The research of new maintenance long-term immunosuppressive agents focuses on costimulation blockade. Agents inhibiting CD40-CD40 ligand interaction may enable a good control of both T cells and B cells responses. Anti-CD28 antibodies may promote regulatory T cells. Agents targeting this costimulation pathways are currently evaluated in clinical trials.Immunosuppressive agents for ABMR treatment are scarce since anti-CD20 agent rituximab and proteasome inhibitor bortezomib have failed to demonstrate an interest in ABMR. New drugs focusing on antibodies removal (imlifidase), B cell and plasmablasts (anti-IL-6/IL-6R, anti-CD38…) and complement inhibition are in the pipeline, with the challenge of their evaluation in such a heterogeneous pathology.

ICOS is upregulated on T cells following radiation and agonism combined with radiation results in enhanced tumor control

Multiple preclinical studies have shown improved outcomes when radiation therapy is combined with immune modulating antibodies. However, to date, many of these promising results have failed to translate to successful clinical studies. This led us to explore additional checkpoint and co-stimulatory pathways that may be regulated by radiation therapy. Here, we demonstrate that radiation increases the expression of inducible T cell co-stimulator (ICOS) on both CD4 and CD8 T cells in the blood following treatment. Moreover, when we combined a novel ICOS agonist antibody with radiation we observed durable cures across multiple tumor models and mouse strains. Depletion studies revealed that CD8 T cells were ultimately required for treatment efficacy, but CD4 T cells and NK cells also partially contributed to tumor control. Phenotypic analysis showed that the combination therapy diminished the increased infiltration of regulatory T cells into the tumor that typically occurs following radiation alone. Finally, we demonstrate in a poorly immunogenic pancreatic tumor model which is resistant to combined radiation and anti-PD1 checkpoint blockade that the addition of this novel ICOS agonist antibody to the treatment regimen results in tumor control. These findings identify ICOS as part of a T cell pathway that is modulated by radiation and targeting this pathway with a novel ICOS antibody results in durable tumor control in preclinical models.

Membrane anchored IL-18 linked to constitutively active TLR4 and CD40 improves human T cell antitumor capacities for adoptive cell therapy

BackgroundAdoptive transfer of tumor-infiltrating lymphocytes (TILs) or blood T cells genetically redirected by an antitumor TCR or CAR induces a strong antitumor response in a proportion of patients with cancer;...

412.10: Blocking of the CD40-CD154 Pathway Inhibits Macrophage Infiltration and Reduces Fibrosis After Renal Transplantation

Introduction: Renal transplantation improves the life expectancy and quality of life of end-stage renal patients. Due to the development of immunosuppressive drugs, the results of short-term renal transplantation have improved significantly, but the long-term survival rate of renal transplantation has hardly changed in the past few decades. Interstitial fibrosis is an important cause of graft loss in chronic allograft renal injury. CD40-CD154 costimulatory pathway block can inhibit T cell activation and prolong the survival of allografts in a variety of transplantation models. In this study, we found that the single use of MR1 (CD154 antibody) can significantly reduce the fibrosis of transplanted kidney. Method: The kidney of BALB/c mice was transplanted into C57BL6/J recipient by orthotopic transplantation. The contralateral kidney of the recipient was removed 1-3 days after transplantation. The MR1 treatment group was intraperitoneally injected with 500ug of MR1 antibody on the day of operation, and the control group was given normal saline at the same time. After 30 days, serum was collected to measure the blood creatinine. The kidney was obtained after cardiac perfusion. PAS staining was used to detect renal injury. The number of T lymphocytes and macrophages and the expression of a-SMA in the transplanted kidney were analyzed by flow cytometry. Sirius red and gomori trichrome staining were used to detect fibrosis. The colocalization of macrophages and a-SMA was detected by multiple immunofluorescence. Results: It was found that serum creatinine from MR1 treatment group was significantly lower than control group. Compared with control group, MR1 treated mice also showed milder renal histological lesions that the loss of brush border of proximal tubules, tubular necrosis, tubular atrophy, protein casting and cell infiltration at the cortical medullary junction were much lower. Sirius red and gomori trichrome staining showed that MR1 treatment group significantly reduced the fibrosis of transplanted kidney. RT-PCR showed that the expressions of collagen deposition related proteins such as ColI and FN mRNA were up-regulated in the control group. Further immunohistochemistry analysis showed that the number of infiltrated macrophages in the MR1 treatment group decreased significantly compared to control group. Through flow cytometry analysis, it was found that the number of macrophages secreting a-SMA in control group were significantly higher than those in MR1 treatment group. The FACS results showed that 92.7%± 2.8% of the infiltrating macrophages were M2 type, and they were all derived from the recipients. Immunofluorescence experiment also confirmed this result. Conclusion: MR1 significantly reduced the fibrosis in kidney graft which may due to less infiltration of M2 macrophages and less a-SMA+ macrophages. National key research and development program 2019YFA0110703. Natural Science Foundation of Hunan Province, China (Grant No.:2021JJ31018).

337.10: Monotherapy With TNX-1500, a Fc-Modified Anti-CD154mAb, Prolongs Cardiac Allograft Survival in Cynomolgus Monkeys

Purpose: Blockade of the CD40/CD154 T cell costimulation pathway is a promising approach to replace conventional clinical immunosuppressive therapy. TNX-1500 (TNX)* is a novel humanized anti-CD154 mAb that contains the hu5c8 Fab region and an Fc region engineered to modulate FcγR2 binding to reduce the risk of thromboembolic events seen with hu5c8 IgG1 in previous clinical trials. Its efficacy was evaluated in cynomolgus monkey heterotopic heart allograft recipients. Methods: Cynomolgus monkey heterotopic cardiac allograft recipients were treated with TNX 30mg/kg iv 2x weekly for 2 weeks, then either a ‘standard-dose’ regimen of 20mg/kg weekly from days 21-180 (sTNX, n=5) or a reduced-dose TNX maintenance regimen (10 mg/kg weekly x6, then 20mg/kg monthly; loTNX), with (loTNX+MMF, n=4) or without mycophenolate mofetil (MMF) at 200mg/d po (loTNX, n=4). In 3 sTNX animals therapy was discontinued on day 175. Results were compared to historical data with hu5c8 monotherapy dosed as for loTNX (n=5). Biopsies or explanted hearts were evaluated at three protocol-defined time-points (d45, d90, d180), at earlier explant. Results: sTNX (MST >232d, range 116-305) significantly prolonged cardiac allograft survival relative to hu5c8 alone (MST 133d; p=0.016), loTNX (MST 99d; p=0.014), or loTNX+MMF (MST 88d; p=0.011). All grafts treated with loTNX () or with loTNX+MMF () exhibited acute rejection histologically within 90 days, and 7 of 8 grafts failed before day 180. One sTNX graft rejected at 116d in association with bacterial infection; one graft was electively explanted at 181d; and three grafts survived for 57, 90, and 130 days after discontinuing TNX-1500. Neither sustained thrombocytopenia nor micro- or macro-vascular thrombosis were observed. At 90 days, loTNX+MMF had a significantly higher median ISHLT score (2.0) than sTNX grafts (0.2; p=0.016); loTNX+MMF also had a significantly higher median CAV score (1.8) at d90 than either loTNX (0.2; p=0.022) or sTNX (0.3; p=0.026). At subsequent graft explant or end-of-study biopsy (180d), loTNX+MMF had a higher median CAV score (2.4) than loTNX (0.4; p=0.002) or sTNX (0.8; p=0.002). sTNX suppressed the rise in Teff/Tregs ratio at the final time-point (180d or <180d if graft failure) more effectively than loTNX+MMF (3.5 ± 0.9 vs 9.5 ± 6.1, p=0.031). sTNX (5/5) but not loTNX (1/4) or loTNX+MMF (2/4) consistently prevented anti-donor antibody elaboration. Conclusions: Blockade of CD154 with sTNX monotherapy was not associated with thrombotic events, well tolerated, and consistently prevented pathogenic alloimmunity in this stringent preclinical model. Lower TNX maintenance dosing, with or without MMF, was less effective. *TNX-1500 is a pre-IND molecule and not approved for any clinical indication. NIH grant P01 HL158504. Tonix Pharmaceuticals. RC is supported by the Benjamin Research Fellowship from the German Research Foundation.

Rapamycin-encapsulated costimulatory ICOS/CD40L-bispecific nanoparticles restrict pathogenic helper T-B-cell interactions while in situ suppressing mTOR for lupus treatment

Excessive CD4+ T helper (Th)–B-cell interactions and loss of Treg homeostasis are crucial to the pathogenesis of systemic lupus erythematosus (SLE). Targeting the SLE-specific upregulated costimulatory molecules ICOS or CD40L on Th can block Th–B reciprocal activation, but single costimulatory molecular blockade exhibited unsatisfactory therapeutic efficacy due to pathway redundancy. As ICOS and CD40L nonredundantly and cooperatively promote Th–B-cell reciprocal activation, simultaneously blocking ICOS and CD40L may achieve a synergistic effect. Moreover, inhibition of overactivated mTOR signaling by rapamycin (RAP) can promote Treg expansion while restraining autoreactive T-B-cell activation, which can work as an adjuvant to pair with costimulation blockade to restore immune homeostasis. However, systemic administration of multiple immune modulators is hindered by limited drug enrichment at the target site and increased systemic toxicity. Here, we rationally designed RAP-encapsulated ICOS/CD40L bispecific nanoparticles (NPs) to achieve multitarget therapy in a disease-specific manner. Through ex vivo cocultures of Th and B cells from SLE mice or patients and in vivo SLE mouse models, we demonstrated that RAP-encapsulated ICOS/CD40L bispecific NPs selectively target SLE Th cells and potently inhibit Th–B-cell reciprocal activation by targeting dual costimulatory pathways. In addition, the sustained release of RAP benefits from the precise targeting ability of bispecific NPs to further inhibit in situ Th–B cells while promote bystander Treg cells, which help to significantly alleviate SLE progression in both inducible and spontaneous lupus models with no obvious toxicity.

Inorganic nanosheets facilitate humoral immunity against medical implant infections by modulating immune co-stimulatory pathways

Strategies to manipulate immune cell co-inhibitory or co-activating signals have revolutionized immunotherapy. However, certain immunologically cold diseases, such as bacterial biofilm infections of medical implants are hard to target due to the complexity of the immune co-stimulatory pathways involved. Here we show that two-dimensional manganese chalcogenophosphates MnPSe3 (MPS) nanosheets modified with polyvinylpyrrolidone (PVP) are capable of triggering a strong anti-bacterial biofilm humoral immunity in a mouse model of surgical implant infection via modulating antigen presentation and costimulatory molecule expression in the infectious microenvironment (IME). Mechanistically, the PVP-modified MPS (MPS-PVP) damages the structure of the biofilm which results in antigen exposure by generating reactive oxidative species, while changing the balance of immune-inhibitory (IL4I1 and CD206) and co-activator signals (CD40, CD80 and CD69). This leads to amplified APC priming and antigen presentation, resulting in biofilm-specific humoral immune and memory responses. In our work, we demonstrate that pre-surgical neoadjuvant immunotherapy utilizing MPS-PVP successfully mitigates residual and recurrent infections following removal of the infected implants. This study thus offers an alternative to replace antibiotics against hard-to-treat biofilm infections.

Pig heart and lung xenotransplantation: Present status.

The recent pig heart transplant in a patient at the University of Maryland Medical Center has stimulated renewed interest in the xenotransplantation of organs from genetically engineered pigs. The barriers to the use of pigs as sources of organs have largely been overcome by 2 approaches - (1) the deletion of expression of the three known pig carbohydrate xenoantigens against which humans have preformed antibodies, and (2) the transgenic introduction of human 'protective' proteins, such as complement-regulatory proteins. These gene modifications, coupled with immunosuppressive therapy based on blockade of the CD40/CD154 costimulation pathway, have resulted in survival of baboons with life-supporting pig heart grafts for almost 9 months. The initial clinical success at the University of Maryland reinforces encouraging preclinical results. It suggests that pig hearts are likely to provide an effective bridge to an allotransplant, but their utility for destination therapy remains uncertain. Because of additional complex immunobiological problems, the same approach has been less successful in preclinical lung xenograft transplantation, where survival is still measured in days or weeks. The first formal clinical trials of pig heart transplantation may include patients who do not have access to an allotransplant, those with contraindications for mechanical circulatory support, those in need of retransplantation or with a high level of panel-reactive antibodies. Infants with complex congenital heart disease, should also be considered.

Dual Costimulatory and Coinhibitory Targeting with a Hybrid Fusion Protein as an Immunomodulatory Therapy in Lupus Nephritis Mice Models.

Systemic lupus erythematosus is a complex autoimmune disorder mostly mediated by B-cells in which costimulatory signals are involved. This immune dysregulation can cause tissue damage and inflammation of the kidney, resulting in lupus nephritis and chronic renal failure. Given the previous experience reported with CTLA4-Ig as well as recent understanding of the PD-1 pathway in this setting, our group was encouraged to evaluate, in the NZBWF1 model, a human fusion recombinant protein (Hybri) with two domains: CTLA4, blocking the CD28—CD80 costimulatory pathway, and PD-L2, exacerbating the PD-1–PD-L2 coinhibitory pathway. After achieving good results in this model, we decided to validate the therapeutic effect of Hybri in the more severe MRL/lpr model of lupus nephritis. The intraperitoneal administration of Hybri prevented the progression of proteinuria and anti-dsDNA antibodies to levels like those of cyclophosphamide and reduced the histological score, infiltration of B-cells, T-cells, and macrophages and immune deposition in both lupus-prone models. Additionally, Hybri treatment produced changes in both inflammatory-related circulating cytokines and kidney gene expression. To summarize, both in vivo studies revealed that the Hybri effect on costimulatory-coinhibitory pathways may effectively mitigate lupus nephritis, with potential for use as a maintenance therapy.

019 Investigating OX40L and its role in mediating cutaneous and systemic autoimmune disease

Systemic lupus erythematosus (SLE) is a devastating systemic inflammatory disease, with prominent female bias. Recent literature suggests the OX40/OX40L costimulatory pathway may play an important role in development of SLE. GWAS have identified TNFSF4 (OX40L) as an SLE susceptibility locus. OX40L stimulation of T cells through the OX40 receptor has been shown to promote a T follicular helper (Tfh) phenotype, and Ox40l knockout has been demonstrated to ameliorate the SLE phenotype in transgenic and induced lupus mouse models.

The Multi-Kinase Inhibitor Lucitanib Enhances the Antitumor Activity of Coinhibitory and Costimulatory Immune Pathway Modulators in Syngeneic Models.

Lucitanib is a multi-tyrosine kinase inhibitor whose targets are associated with angiogenesis and other key cancer and immune pathways. Its antiangiogenic properties are understood, but lucitanib's immunomodulatory activity is heretofore unknown. Lucitanib exhibited such activity in vivo, increasing CD3 + , CD8 + , and CD4 + T cells and decreasing dendritic cells and monocyte-derived suppressor cells in mouse spleens. Depletion of CD8 + T cells from syngeneic MC38 colon tumor-bearing mice reduced the antitumor efficacy of lucitanib and revealed a CD8 + T-cell-dependent component of lucitanib's activity. The combination of lucitanib and costimulatory immune pathway agonists targeting 4-1BB, glucocorticoid-induced TNFR (GITR), inducible T-cell co-stimulator (ICOS), or OX40 exhibited enhanced antitumor activity compared with each single agent in immunocompetent tumor models. Lucitanib combined with blockade of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or programmed cell death protein-1 (PD-1) coinhibitory immune pathways also showed enhanced antitumor activity over the single agents in multiple models. In CT26 tumors, lucitanib, alone or combined with anti-PD-1, reduced CD31 + vessels and depleted F4/80 + macrophages. Combination treatment also increased the number of intratumoral T cells. Gene expression in pathways associated with immune activity was upregulated by lucitanib in MC38 tumors and further potentiated by combination with anti-PD-1. Accordingly, lucitanib, alone or combined with anti-PD-1, increased intratumoral CD8 + T-cell abundance. Lucitanib's antitumor and pharmacodynamic activity, alone or combined with anti-PD-1, was not recapitulated by specific vascular endothelial growth factor receptor-2 (VEGFR2) inhibition. These data indicate that lucitanib can modulate vascular and immune components of the tumor microenvironment and cooperate with immunotherapy to enhance antitumor efficacy. They support the clinical development of lucitanib combined with immune pathway modulators to treat cancer.

Kidney xenotransplantation in a brain-dead donor: Glass half-full or half-empty?

Kidney xenotransplantation in a brain-dead donor: Glass half-full or half-empty?

Lentivirus-mediated PD-L1 overexpression in bone marrow-derived dendritic cells induces immune tolerance in a rat keratoplasty model

PurposeThe side effects of immune suppressants on immune rejection have become increasingly apparent after keratoplasty. To find out new alternative immunotherapy strategies, we studied the role of programmed death-1 (PD-1) and its ligand (PD-L1) co-stimulatory pathway in inducing immune tolerance of rat keratoplasty. MethodsThe PD-L1 protein was constitutively overexpressed via lentiviral transduction in bone marrow-derived dendritic cells (BMDCs) from rats, then infused via the tail vein into rats before undergoing keratoplasty. Western blot analysis of PD-L1 protein confirmed the effectiveness of lentivirus-mediated. The phenotype of immature BMDC was confirmed by flow cytometry analysis with CD80, CD86, CD11c and MHC-II antibodies. To investigate the mechanism of the immune tolerance induced by BMDCs transfusion, PD-L1, IFN-γ and IL-17 in serum and cell culture supernatant were assessed by ELISA and qPCR. ResultsAfter LPS stimulation, immature dendritic cells with over-expression of PD-L1 still showed high expression of PD-L1(p < 0.001), and low expression of IL-17 and IFN-γ (p < 0.001), which reduced neovascularization (p < 0.05), and prolonged the survival after corneal implants. ConclusionImmature DC cells with overexpression of PD-L1 have low ability to activate T cells，which is a potential treatment for avoiding graft rejection by promoting natural immunosuppression. This cellular treatment is expected to reduce the use of immune suppressants and the occurrence of side effects.