Acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, demonstrates efficacy in systemic sclerosis preclinical mouse models

Background Uncontrolled immune response with T cell activation has a key role in the pathogenesis of systemic sclerosis (SSc), a disorder that is characterized by generalized fibrosis affecting particularly the lungs and skin. Costimulatory molecules are key players during immune activation, and recent evidence supports a role of CD28 and ICOS in the development of fibrosis. We herein investigated the efficacy of acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, in two complementary SSc-related mouse models recapitulating skin fibrosis, interstitial lung disease, and pulmonary hypertension. Methods Expression of circulating soluble ICOS and skin-expressed ICOS was investigated in SSc patients. Thereafter, acazicolcept was evaluated in the hypochlorous acid (HOCL)-induced dermal fibrosis mouse model and in the Fra-2 transgenic (Tg) mouse model. In each model, mice received 400 μg of acazicolcept or a molar-matched dose of an Fc control protein twice a week for 6 weeks. After 6 weeks, skin and lung were evaluated. Results ICOS was significantly increased in the sera from SSc patients and in SSc skin biopsies as compared to samples from healthy controls. Similar body weight changes were observed between Fc control and acazicolcept groups in both HOCL and Fra-2 Tg mice suggesting a good tolerance of acazicolcept treatment. In mice challenged with HOCL, acazicolcept induced a significant decrease in dermal thickness, collagen content, myofibroblast number, and inflammatory infiltrates characterized by B cells, T cells, neutrophils, and macrophages. In the Fra-2 Tg mouse model, acazicolcept treatment reduced lung collagen content, fibrillar collagen, histological fibrosis score, and right ventricular systolic pressure (RVSP). A reduction in frequency of CD4+ and T effector memory cells and an increase in the percentage of CD4+ T naïve cells in spleen and lung of acazicolcept-treated Fra-2 Tg mice was observed as compared to Fc control-treated Fra-2 Tg mice. Moreover, acazicolcept reduced CD69 and PD-1 expression on CD4+ T cells from the spleen and the lung. Target engagement by acazicolcept was demonstrated by blockade of CD28 and ICOS detection by flow cytometry in treated mice. Conclusions Our results confirm the importance of costimulatory molecules in inflammatory-driven fibrosis. Our data highlight a key role of ICOS and CD28 in SSc. Using complementary models, we demonstrated that dual ICOS/CD28 blockade by acazicolcept decreased dermal and pulmonary fibrosis and alleviated pulmonary hypertension. These results pave the way for subsequent research on ICOS/CD28-targeted therapies.

AC099850.3 Promotes Cell Proliferation and is One of Five Costimulatory Molecule-Related LncRNAs That Predict Overall Survival of Liver Hepatocellular Carcinoma

Background: Extensive research has revealed that costimulatory molecules play central roles in mounting anti-tumor immune responses and long non‐coding RNA (lncRNA) is an important regulatory factor in the development of various cancers. However, their roles in liver hepatocellular carcinoma (HCC) remain unexplored. In this study, we aimed to explore costimulatory molecule-related lncRNAs in HCC and construct a prognostic signature to predict prognosis and improve clinical outcomes with HCC patients.Methods: The data we used for bioinformatics analysis were downloaded from The Cancer Genome Atlas database. Costimulatory molecules were obtained from the known literature. The R software, SPSS and GraphPad Prism were used for mapping and statistical analysis.Results: A five costimulatory molecule-related lncRNAs based risk model was initially constructed through lasso and Cox regression analysis. Moreover, multivariate regression suggested that the risk score was a significant prognostic risk factor in HCC. Samples in high- and low-risk groups exhibited significantly different in gene set enrichment analysis and immune infiltration analysis. Importantly, we found that the AC099850.3 were significantly related to cell proliferation in HCC according to the colony formation and CCK8 assays.Conclusion: In summary, we first identified and validated a novel costimulatory molecule-related survival model and we found that AC099850.3 is closely associated with clinical stage and could remarkably facilitate cell proliferation in HCC, making it potential to be a novel therapeutic target.

Mutation in Irf8 Gene (Irf8R294C) Impairs Type I IFN-Mediated Antiviral Immune Response by Murine pDCs

Plasmacytoid dendritic cells (pDCs) are the key producers of type I interferons (IFNs), thus playing a central role in initiating antiviral immune response. Besides robust type I IFN production, pDCs also act as antigen presenting cells post immunogenic stimulation. Transcription factor Irf8 is indispensable for the development of both pDC and cDC1 subset. However, the mechanism underlying the differential regulation by IRF8 in cDC1- and pDC-specific genomic architecture of developmental pathways still remains to be fully elucidated. Previous studies indicated that the Irf8R294C mutation specifically abrogates development of cDC1 without affecting that of pDC. In the present study using RNA-seq based approach, we have found that though the point mutation Irf8R294C did not affect pDC development, it led to defective type I IFN production, thus resulting in inefficient antiviral response. This observation unraveled the distinctive roles of IRF8 in these two subpopulations—regulating the development of cDC1 whereas modulating the functionality of pDCs without affecting development. We have reported here that Irf8R294C mutation also caused defect in production of ISGs as well as defective upregulation of costimulatory molecules in pDCs in response to NDV infection (or CpG stimulation). Through in vivo studies, we demonstrated that abrogation of type I IFN production was concomitant with reduced upregulation of costimulatory molecules in pDCs and increased NDV burden in IRF8R294C mice in comparison with wild type, indicating inefficient viral clearance. Further, we have also shown that Irf8R294C mutation abolished the activation of type I IFN promoter by IRF8, justifying the low level of type I IFN production. Taken together, our study signifies that the single point mutation in Irf8, Irf8R294C severely compromised type I IFN-mediated immune response by murine pDCs, thereby causing impairment in antiviral immunity.

CD33 BiTE ® Construct Mediated Immunological Synapse Formation and Downstream Signaling in T Cells Is Dependent on Expression of Costimulatory Molecules on Target Cells

BiTE ® (Bispecific T-cell Engager) constructs represent a novel immunotherapeutic strategy that recruits T cells against cancer cells independent of their TCR specificity. Currently, two CD33xCD3 BiTE ® antibody constructs (AMG 330 & AMG 673) are being investigated in phase I dose escalation trials in patients with relapsed/refractory Acute Myeloid Leukemia (AML) with early evidence of acceptable safety and anti-leukemic activity (Ravandi et al., ASH 2020; Subklewe et al., EHA 2020). So far, details of BiTE ® mediated T-cell engagement and information on parameters contributing to their efficacy need more investigation. Therefore, we aimed to characterize the interplay between target and effector cells to deepen our mechanistic understanding of BiTE ® construct mediated T-cell engagement. Previously, we have created a novel in vitro model system with murine Ba/F3 cells expressing human (hu) CD33 ± huCD80 ± huCD86 ± huPD-L1 to study T-cell proliferation and cytotoxicity induced by AMG 330. Using that system, we showed that expression of T-cell co-signaling receptors on target cells modulate AMG 330 induced T-cell activity (Marcinek et al., ASH 2018, EHA 2019). Here, we hypothesize that expression of costimulatory molecules impacts BiTE ® mediated immune synapse formation and consecutive downstream signaling in BiTE ® construct activated T cells. To study whether AMG 330 can induce synapse formation and TCR triggering we used a previously described reconstituted T-cell system, which consists of non-immune (HEK) cells introduced with genes encoding the TCR and other proteins (e.g. CD45) required for the regulation of TCR phosphorylation (James et al., Nature 2012). HEK-T cells were incubated with huCD33 transduced RajiB cells in presence of fluorescently labeled AMG 330 or a control BiTE® (cBiTE) construct to allow cell conjugation. A spinning disc confocal microscope system was used to image cells. To pinpoint the role of T-cell co-signaling receptors in immune synapse formation we incubated differentBa/F3 cell constructs or primary AML (pAML) cells with healthy donor T cells in the presence of AMG 330 and analyzed intensity of LFA-1 expression within the synapse using an Imaging Flow Cytometer. Furthermore, we determined phosphorylation of ZAP70, AKT and ERK in conjugated T cells after various time points by phosphoflow cytometry. We observed that AMG 330, in contrast to cBiTE®, induced TCR triggering reflected by exclusion of CD45 from the RajiB-T-cell-interface. Simultaneously clustering of CD33 occurred in AMG 330 induced cell-cell-interfaces (Fig. 1A/B). The percentage of conjugates formed with huCD33 + Ba/F3 cells was significantly higher in constructs expressing huCD86, compared to those expressing no costimulatory antigens or additional huPD-L1 (Mean % in huCD33 + Ba/F3: 2.8 vs. huCD33 + CD86 +.Ba/F3: 4.2 [p=0.0031] vs. huCD33 + huCD86 + PD-L1 + Ba/F3: 2.8 [p=0.0018]). This was accompanied by LFA-1 accumulation within the T-cell-Ba/F3 cell synapse (Mean of MFI in huCD33 + CD86 +.Ba/F3: 10,933 > huCD33 + huCD86 + PD-L1 + Ba/F3: 7,749 > huCD33 + Ba/F3: 7,028). For downstream signaling in T cells after engagement with Ba/F3 cell constructs in the presence of AMG 330, we observed that kinase phosphorylation was highest after 10 minutes in CD86 co-expressing Ba/F3 cells (Mean % of phosphorylation in T-cell conjugates with huCD33 + vs huCD33 + huCD86 + vs huCD33 + CD86 +.PD-L1 + Ba/F3: pERK 40.9 vs 54.3 [p=0.0064] vs 51.2 %; pAKT: 69.1 vs 81.5 [p=0.0642] vs 75.1 %; pZAP70: 6.9 vs 12.2 [p<0.0001] vs 7.7 % [p<0.0001]) (Fig. 1C). Finally, we evaluated if these finding could also be observed in pAML samples. For that, we determined LFA-1 expression intensity within AMG 330-induced pAML-T-cell synapses. We used CD33 + pAML samples with either high CD86 and no PD-L1 expression or vice versa. Comparing synapse formation between these samples, LFA-1 intensity was 4.6-fold higher in the CD86 + PD-L1 - sample compared to the CD86 - PD-L1 + pAML. Taken together, our data unravel molecular mechanisms of BiTE® construct induced immune synapse formation, highlighting the role of costimulatory molecules in this process. They support the notion that T cell co-signaling receptors like CD86 and PD-L1 modulate T-cell response in an early event manner. Prospective analyses in clinical trials are needed to validate the relevance of checkpoint molecule expression on target cells as a potential predictive biomarker for response. Figure 1 Figure 1. Disclosures Brauchle: Adivo: Current Employment. Lacher: Roche: Research Funding. Kischel: Amgen GmbH Munich: Current Employment. von Bergwelt: Roche: Honoraria, Research Funding, Speakers Bureau; Miltenyi: Honoraria, Research Funding, Speakers Bureau; Mologen: Honoraria, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Astellas: Honoraria, Research Funding, Speakers Bureau; MSD Sharpe & Dohme: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau. Theurich: Amgen: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Buecklein: Novartis: Consultancy, Other: congress and travel support, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Miltenyi: Research Funding; Kite/Gilead: Consultancy, Honoraria, Other: Congress and travel support, Research Funding; BMS/Celgene: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Subklewe: Janssen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Roche: Research Funding; Novartis: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Klinikum der Universität München: Current Employment; Takeda: Speakers Bureau; MorphoSys: Research Funding; Miltenyi: Research Funding; Gilead: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; BMS/Celgene: Consultancy, Research Funding, Speakers Bureau.

165 Generating enhanced tumor infiltrating lymphocytes through microfluidic cell squeezing

BackgroundTumor Infiltrating Lymphocyte (TIL) therapies have shown significant solid tumor activity in patients, but current TIL compositions require patient lymphodepletion and high dose IL-2 after cell infusion to support clinical activity. Removing this requirement through ex vivo engineering of the TIL product with mRNA could enhance potency, expand the potential patient population, and potentially allow for repeat dosing and concomitant treatment with checkpoint therapies.MethodsTo transiently overexpress both membrane-bound cytokines and costimulatory molecules, we used microfluidic cell squeezing (Cell Squeeze®) to deliver mRNA directly to the cytosol of expanded tumor reactive CD8 human TILs (AGX-148). After mRNA delivery, the TILs were cultured in media with varying levels of exogenous IL-2 and characterized by flow cytometry.ResultsWe demonstrated that multiple mRNA constructs delivered simultaneously by microfluidic cell squeezing to human TILs are highly expressed (>80% of cells) for multiple days while maintaining high viability (>80%) in vitro. Membrane bound cytokines are able to support cell expansion in the absence of exogenous IL-2 at rates comparable to control cells incubated with a high concentration of IL-2 for up to 3 days. Furthermore, we have identified a membrane-bound cytokine that alters the TIL phenotype as quantified by multiple markers, including increased L-selectin (CD62L), which is an indicator of central memory T cells.ConclusionsThrough microfluidic cell squeeze delivery of mRNAs, we have created enhanced TILs with high levels of membrane-bound cytokines and/or costimulatory molecules in vitro. These cells are able to proliferate without exogenous IL-2 and have an improved phenotype.

Costimulatory Molecule Expression Profile as a Biomarker to Predict Prognosis and Chemotherapy Response for Patients With Small-cell Lung Cancer

Background: Small cell lung cancer (SCLC) is the deadliest pathological subtype of lung cancer with few precise treatment options. Owing to the paucity of specimens, progress in identifying prognostic and therapeutic biomarkers for SCLC has been stagnant for decades. Considering the costimulatory molecules are essential elements in modulating anti-tumor immune responses and determining therapeutic response, we decided to conduct a comprehensive analyses of costimulatory molecule expression profile with regard to prognosis and chemotherapy response for SCLCs for the first time. Methods: We systematically explored the molecular characteristics and clinical relevance of costimulatory molecules in SCLC. Using a univariate Cox and LASSO Cox model, we then constructed a molecule-based signature (CMS) based on our examination of 208 cases with SCLC from two different cohorts—including an independent cohort that contained 131 cases with qPCR data, to predict the outcome and chemotherapy response for SCLCs. Relationships between the CMS and adjuvant chemotherapy (ACT) benefits and inflammatory landscape were also evaluated.Results: We found T cell activation was restrained in SCLCs, and costimulatory molecules exhibited widespread abnormal genetic alterations and expression. Then, the CMS containing 7 molecules (ICOSLG, EDA2R, TNFRSF25, CD276, RELT, PDCD1, and TNFSF14) was built with a training cohort of 77 cases, which successfully divided patients into high- or low-risk groups with significantly different prognosis and chemotherapy benefit (both P<0.001). The CMS was well validated in the independent cohort with qPCR data. ROC and C-index analysis confirmed the superior predictive performance of the CMS in comparison with other clinicopathological parameters from different cohorts. Importantly, the CMS was confirmed as a significantly independent prognosticator for clinical outcomes and chemotherapy response in SCLCs through multivariate Cox analysis. Further analysis revealed that low-risk patients were characteristic by an activated immune phenotype with distinct expression of immune checkpoints.Conclusions: We firstly uncovered the expression heterogeneity of costimulatory molecules in SCLC, and successfully constructed a novel predictive CMS. The identified signature contributed to more accurate patient stratification and provided robust prognostic value in estimating survival and the clinical response to chemotherapy, allowing optimization of treatment and prognosis management for patients with SCLC.

Serum levels of inhibitory costimulatory molecules and correlations with levels of innate immune cytokines in patients with pulmonary tuberculosis

Objective To analyze serum levels of inhibitory costimulatory molecules and their correlations with innate immune cytokine levels in patients with pulmonary tuberculosis (PTB). Methods Data for 280 PTB patients and 280 healthy individuals were collected. Serum levels of immune molecules were measured using ELISA. Univariate, multivariate, subgroup, matrix correlation, and receiver operating characteristic curve analyses were performed. Results Host, environment, lifestyle, clinical features, and medical history all influenced PTB. Serum levels of soluble programmed death ligand 1 (sPD-L1), soluble T-cell immunoglobulin- and mucin-domain–containing molecule 3 (sTim-3), soluble galectin-9 (sGal-9), interleukin (IL)-4, and IL-33 were significantly higher in patients with PTB, while levels of IL-12, IL-23, IL-18, and interferon (IFN)-γ were significantly lower. Serum levels of sTim-3 were higher in alcohol users. Levels of sTim-3 were negatively correlated with those of IL-12. Levels of IL-12, IL-23, and IL-18 were positively correlated with those of IFN-γ, while levels of IL-12 were negatively correlated with those of IL-4. The areas under the curve of sPD-L1, sTim-3, sGal-9, IL-12, IL-23, IL-18, IFN-γ, IL-4, and IL-33 for identifying PTB were all >0.77. Conclusions Inhibitory costimulatory molecules may be targets for controlling PTB. Immune molecules may be helpful for diagnosis of PTB.

Absence of CD28-CTLA4-PD-L1 Costimulatory Molecules Reduces Herpes Simplex Virus 1 Reactivation

Costimulatory molecules play an important role in activation of T cell responses, and T cells contribute to HSV-1-induced eye disease in the host. Similar to HSV-1 ICP22, the cellular costimulatory molecules CD28, CTLA4, and PD-L1 also bind to CD80.

Antitumor Activities of Immune Costimulatory Molecules of TNF Superfamily in Colorectal and Lung Cancers

Cancer immunotherapy has emerged as a promising treatment that utilizes the innate or adaptive immunity to generate a robust killing of malignant cells. However, only a limited number of cancer patients showed responsiveness to immunotherapies such as checkpoint inhibitors, suggesting the need for potent alternative strategies. In the present study, we explored the therapeutic potentials of costimulatory molecules including TNF superfamily member 4 (TNFSF4), member 9 (TNFSF9), and member 18 (TNFSF18). In tumor samples from human colorectal and lung cancer patients, expression of these factors positively correlated with lymphocyte infiltration and expression of several immune effector genes. In syngeneic mouse tumor models, overexpression of the TNF superfamily costimulatory factors in murine colorectal or lung cancer cells significantly suppressed tumor progression. Especially, TNFSF9 and 18 showed stronger antitumor effects than TNFSF4. Together, our study demonstrated the great potential of cancer immunotherapy targeting these immune costimulatory molecules.

IFNγ, and to a Lesser Extent TNFα, Provokes a Sustained Endothelial Costimulatory Phenotype

BackgroundVascular endothelial cells (EC) are critical for regulation of local immune responses, through coordination of leukocyte recruitment from the blood and egress into the tissue. Growing evidence supports an additional role for endothelium in activation and costimulation of adaptive immune cells. However, this function remains somewhat controversial, and the full repertoire and durability of an enhanced endothelial costimulatory phenotype has not been wholly defined.MethodsHuman endothelium was stimulated with continuous TNFα or IFNγ for 1-48hr; or primed with TNFα or IFNγ for only 3hr, before withdrawal of stimulus for up to 45hr. Gene expression of cytokines, costimulatory molecules and antigen presentation molecules was measured by Nanostring, and publicly available datasets of EC stimulation with TNFα or IFNγ were leveraged to further corroborate the results. Cell surface protein expression was detected by flow cytometry, and secretion of cytokines was assessed by Luminex and ELISA. Key findings were confirmed in primary human endothelial cells from 4-6 different vascular beds.ResultsTNFα triggered mostly positive immune checkpoint molecule expression on endothelium, including CD40, 4-1BB, and ICOSLG but in the context of only HLA class I and immunoproteasome subunits. IFNγ promoted a more tolerogenic phenotype of high PD-L1 and PD-L2 expression with both HLA class I and class II molecules and antigen processing genes. Both cytokines elicited secretion of IL-15 and BAFF/BLyS, with TNFα stimulated EC additionally producing IL-6, TL1A and IL-1β. Moreover, endothelium primed for a short period (3hr) with TNFα mostly failed to alter the costimulatory phenotype 24-48hr later, with only somewhat augmented expression of HLA class I. In contrast, brief exposure to IFNγ was sufficient to cause late expression of antigen presentation, cytokines and costimulatory molecules. In particular HLA class I, PD-1 ligand and cytokine expression was markedly high on endothelium two days after IFNγ was last present.ConclusionsEndothelia from multiple vascular beds possess a wide range of other immune checkpoint molecules and cytokines that can shape the adaptive immune response. Our results further demonstrate that IFNγ elicits prolonged signaling that persists days after initiation and is sufficient to trigger substantial gene expression changes and immune phenotype in vascular endothelium.