Fc Region Of Human IgG1 Research Articles

Belatacept-related cytomegalovirus infection: Advocacy for tailored immunosuppression based on individual assessment of immune fitness

Belatacept, a fusion protein combining CTLA-4 and the Fc region of human IgG1, is increasingly used as a calcineurin inhibitor–sparing regimen in patients with chronic graft dysfunction. Older kidney transplant recipients, particularly from expanded criteria donors, may be switched to belatacept due to poor renal recovery. However, late-onset cytomegalovirus (CMV) reactivation is increasingly reported with this treatment, especially in older patients with graft dysfunction. This suggests a progressive loss of CMV-specific T cell response, potentially driven by T cell exhaustion. Contributing factors include preexisting T cell dysfunction, increased viral antigen exposure, and interference in the PD-L1/PD-1 pathway by belatacept. mTOR inhibitors have shown efficacy in preventing CMV reactivation by reinvigorating CMV-specific T cells. These findings support combining belatacept with mTOR inhibitors in high-risk CMV-seropositive recipients and emphasize the need for personalized immune assessments to guide immunosuppressive strategies.

Multivalent CXCR4-targeting nanobody formats differently affect affinity, receptor clustering, and antagonism

The chemokine receptor CXCR4 is involved in the development and migration of stem and immune cells but is also implicated in tumor progression and metastasis for a variety of cancers. Antagonizing ligand (CXCL12)-induced CXCR4 signaling is, therefore, of therapeutic interest. Currently, there are two small-molecule CXCR4 antagonists on the market for the mobilization of hematopoietic stem cells. Other molecules with improved potencies and safety profiles are being developed for different indications, including cancer. Moreover, multiple antagonistic nanobodies targeting CXCR4 displayed similar or better potencies as compared to the CXCR4-targeting molecule AMD3100 (Plerixafor), which was further enhanced through avid binding of bivalent derivatives. In this study, we aimed to compare the affinities of various multivalent nanobody formats which might be differently impacted by avidity. By fusion to a flexible GS-linker, Fc-region of human IgG1, different C4bp/CLR multimerization domains, or via site-directed conjugation to a trivalent linker scaffold, we generated different types of multivalent nanobodies with varying valencies ranging from bivalent to decavalent. Of these, C-terminal fusion, especially to human Fc, was most advantageous with a 2-log-fold and 3-log-fold increased potency in inhibiting CXCL12-mediated Gαi- or β-arrestin recruitment, respectively. Overall, we describe strategies for generating multivalent and high-potency CXCR4 antagonistic nanobodies able to induce receptor clustering and conclude that fusion to an Fc-tail results in the highest avidity effect irrespective of the hinge linker.

Aluminum hydroxide and immunostimulatory glycolipid adjuvant combination for enhanced COVID-19 subunit vaccine immunogenicity

Protein-based subunit vaccines like RBD-Fc are promising tools to fight COVID-19. RBD-Fc fuses the receptor-binding domain (RBD) of the SARS-CoV-2 virus spike protein with the Fc region of human IgG1, making it more immunogenic than RBD alone. Earlier work showed that combining RBD-Fc with iNKT cell agonists as adjuvants improved neutralizing antibodies but did not sufficiently enhance T cell responses, a limitation RBD-Fc vaccines share with common adjuvants. Here we demonstrate that aluminum hydroxide combined with α-C-GC, a C-glycoside iNKT cell agonist, significantly improved the RBD-Fc vaccine’s induction of RBD-specific T-cell responses. Additionally, aluminum hydroxide with α-GC-CPOEt, a phosphonate diester derivative, synergistically elicited more robust neutralizing antibodies. Remarkably, modifying αGC with phosphate (OPO3H2) or phosphonate (CPO3H2) to potentially enhance aluminum hydroxide interaction did not improve efficacy over unmodified αGC with aluminum hydroxide. These findings underscore the straightforward yet potent potential of this approach in advancing COVID-19 vaccine development and provide insights for iNKT cell-based immunotherapy.

Characterization of plant produced VHH antibodies against cobra venom toxins for antivenom therapy

Cobra (Naja kaouthia) venom contains many toxins including α-neurotoxin (αNTX) and phospholipase A2 (PLA2), which can cause neurodegeneration, respiratory failure, and even death. The traditional antivenom derived from animal serum faces many challenges and limitations. Heavy-chain-only antibodies (HCAb), fusing VHH with human IgG Fc region, offer advantages in tissue penetration, antigen binding, and extended half-life. This research involved the construction and transient expression of two types of VHH-FC which are specific to α-Neurotoxin (VHH-αNTX-FC) and Phospholipase A2 (VHH-PLA2-FC) in Nicotiana benthamiana leaves. The recombinant HCAbs were incubated for up to six days to optimize expression levels followed by purification by affinity chromatography and characterization using LC/Q-TOF mass spectrometry (MS). Purified proteins demonstrated over 92 % sequence coverage and an average mass of around 82 kDa with a high-mannose N-glycan profile. An antigen binding assay showed that the VHH-αNTX-Fc has a greater ability to bind to crude venom than VHH-PLA2-Fc.

Safety and clinical activity of TTI-621 in combination with doxorubicin in patients with unresectable or metastatic high-grade leiomyosarcoma: Results from the low-dose expansion cohort.

11508 Background: TTI-621 is a recombinant fusion protein combining the Fc region of human IgG1 with a fragment of human SIRPα, designed as a decoy receptor for CD47 on tumor cells to interrupt CD47-SIRPα signaling and promote macrophage-mediated phagocytosis of tumor cells as well as activation of NK cells. Preclinical studies suggest TTI-621 may enhance the response to doxorubicin in macrophage-rich tumors that express CD47, such as leiomyosarcoma (LMS). A phase 1/2 dose escalation study with high- and low-dose expansion cohorts evaluating TTI-621 + doxorubicin in patients (pts) with advanced LMS is ongoing (NCT04996004); results from the low-dose expansion cohort are presented. Methods: This open-label study enrolled anthracycline-naïve pts aged ≥18 y with evaluable unresectable or metastatic high-grade LMS and ≤1 prior line of therapy for advanced disease. Pts in the low-dose expansion cohort received TTI-621 0.2 mg/kg on Days 1 and 8 in combination with doxorubicin 75 mg/m2 on Day 1 of 21-day cycles for a maximum 6 cycles, followed by TTI-621 monotherapy on Days 1 and 15 of 28-day cycles until objective disease progression. Primary objectives for the expansion phase were evaluation of safety and investigation of clinical activity via assessment of overall response and clinical benefit rates as defined by RECIST v1.1 criteria. Results: At data cut-off (Oct 3, 2022), 23 pts were evaluable for safety and 20 for clinical response. In the safety population, 39% had received prior treatment for advanced disease. Two pts (9%) experienced Grade ≥3 AE assessed as related to TTI-621 treatment: pancreatitis (n = 1, 4%) and platelet count decreased (n = 1, 4%). Seven pts (30%) experienced Grade ≥3 AE related to the combination of TTI-621 and doxorubicin, including two pts (9%) each with platelet count decreased and white blood cell count decreased and three pts (13%) with neutrophil count decreased. Grade ≥3 doxorubicin-related AEs were more common (n = 17, 74%); most frequent were neutrophil count decreased (n = 8; 35%), white blood cell count decreased (n = 7; 30%), and neutropenia (n = 6; 26%). One pt experienced an infusion-related reaction (Grade 1 chills) assessed as related to TTI-621. No pts attained complete response, but one pt had a complete resolution of all target lesions. Five pts (25%) attained partial response for an overall response rate of 25%; 11 pts (55%) attained stable disease for a disease control rate of 80%. Conclusions: Addition of TTI-621 to doxorubicin showed promising clinical activity and a favorable safety profile among pts with advanced LMS, including those with prolonged exposure to TTI-621 ( > 360 d). Clinical trial information: NCT04996004 .

Abstract CT034: GLIMMER-01: initial results from a phase 1 dose escalation trial of a first-in-class bi-sialidase (E-602) in solid tumors

Abstract Background: Hypersialylation (excessive sialoglycans) on tumor cells has been known to be associated with poorer cancer outcomes for more than 40 years. Sialoglycans are immune suppressive and promote tumor immune evasion by binding to sialoglycan receptors (e.g. Siglecs) expressed on immune cells. However, redundant immune cell expression among Siglecs has posed a challenge for receptor-targeting therapeutic approaches. E-602 is a first-in-class fusion protein of engineered human sialidase (Neu2) and a human IgG1 Fc region. The dimeric sialidase moieties of E-602 circumvent the redundancy of this biology by directly cleaving terminal sialic acid residues from sialoglycans on immune and tumor cells. In preclinical studies, E-602 enhanced immune function by augmenting antigen-specific priming and activation of T cells and restoring function of exhausted-like T cells, and E-602 demonstrated antitumor activity as monotherapy in multiple mouse tumor models. Methods: A Phase 1/2 first-in-human dose escalation study is evaluating the safety, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity of E-602 in patients with advanced cancers. Eligible patients with select advanced solid tumors were treated with E-602 IV once weekly at dose levels between 1 and 30 mg/kg. Circulating immune cells were analyzed for changes in sialylation and immunophenotyping by flow cytometry. Changes in circulating cytokines were measured by immunoassays. Results: As of January 6, 2023, 32 patients were treated with at least one dose of E-602. The most common tumors treated were colorectal (n=18) and pancreatic (n=6). Doses up to 30 mg/kg were tolerated with no dose-limiting toxicities. The most frequent adverse event was infusion-related reactions which were primarily grade 1-2 and clinically manageable. PK was linear across the evaluated dose range with an estimated T1/2 of 9-24 hours. Dose dependent PD observations included (1) desialylation of peripheral CD8+ T, CD4+ T, and NK cells, remaining detectable in some patients at 7 days post-dose; (2) increases in the immune activation marker, CD69, on peripheral CD8+ T, CD4+ T, and NK cells; and (3) increases in the IFNγ-dependent chemokine CXCL10, TNF-α, and MIP1-β. Thus far, response-evaluable patients have had stable or progressive disease. Additional safety, PK, PD, and clinical outcomes for other patients treated as part of backfill at multiple dose levels will be reported at the meeting. Conclusion: E-602 is tolerated at doses up to 30 mg/kg. Consistent with preclinical findings, dose-dependent desialylation and immune system activation were observed. Based on the observed tolerability and PD effects, the Phase 2 portion of the study to evaluate clinical activity of E-602 monotherapy in patients with checkpoint-inhibitor resistant NSCLC and melanoma will proceed. Citation Format: Jason J. Luke, Melissa Johnson, Anthony Tolcher, Christopher T. Chen, Tong Dai, Brendan D. Curti, Anthony El-Khoueiry, Mario Sznol, Brian S. Henick, Christine Horak, Pushpa Jayaraman, Christopher B. Cole, Dawn Wilson, Lizhi Cao, Li Peng, David Feltquate, Deanne Lathers, Manish R. Sharma. GLIMMER-01: initial results from a phase 1 dose escalation trial of a first-in-class bi-sialidase (E-602) in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT034.

Immunogenicity and efficacy of recombinant subunit SARS-CoV-2 vaccine candidate in the Syrian hamster model

SARS-CoV-2 causes devastating impact on the human population and has become a major public health concern. The frequent emergence of SARS-CoV-2 variants of concern urges the development of safe and efficacious vaccine against SARS-CoV-2 variants. We developed a candidate vaccine Baiya SARS-CoV-2 Vax 1, based on SARS-CoV-2 receptor-binding domain (RBD) by fusing with the Fc region of human IgG. The RBD-Fc fusion was produced in Nicotiana benthamiana. Previously, we reported that this plant-produced vaccine is effective in inducing immune response in both mice and non-human primates. Here, the efficacy of our vaccine candidate was tested in Syrian hamster challenge model. Hamsters immunized with two intramuscular doses of Baiya SARS-CoV-2 Vax 1 induced neutralizing antibodies against SARS-CoV-2 and protected from SARS-CoV-2 challenge with reduced viral load in the lungs. These preliminary results demonstrate the ability of plant-produced subunit vaccine Baiya SARS-CoV-2 Vax 1 to provide protection against SARS-CoV-2 infection in hamsters.

Site-Specific Glycan Microheterogeneity Evaluation of Aflibercept Fusion Protein by Glycopeptide-Based LC-MSMS Mapping

The evaluation of the protein glycosylation states of samples of aflibercept obtained from three different regions was conducted by site-specific N-linked glycan microheterogeneity profiling. Glycopeptide-based nano-LC MSMS mapping of tryptic-digested samples of each aflibercept lot provided site-specific information about glycan microheterogeneity on each of the five N-glycosylation sites (two sites in the VEGFR-1 region, two sites in the VEGFR-2 region, and one site in the human IgG Fc region). Next, the glycopeptide-mapping results obtained from the three different aflibercept lots were compared to evaluate the similarity between the samples. Three aflibercept lots showed a high degree of similarity in glycan composition, fucosylation level, sialylation level, and branching, when all five N-glycosylation sites were assessed together as a group. On the other hand, noticeable variations between lots in the glycan types and sialylation levels on the two sites of the VEGFR-2 domain were observed when each of the five N-glycosylation sites were assessed using the glycopeptide-based method. The presence of N-glycolylneuraminic acid (NeuGc) glycans, which may mediate adverse immune reactions in antibody therapeutics, were also detected on the sites of VEGFR1 and VEGFR2 domains, but not on the IgG Fc domain site. These results imply that analyses of the glycosylation profiles of fusion proteins containing multiple N-glycosylation sites, such as aflibercept, being done as a part of quality control for the therapeutics manufacturing process or for biosimilar development, can be done with a more applicable outcome by assessing each site separately.

A recombinant subunit vaccine candidate produced in plants elicits neutralizing antibodies against SARS-CoV-2 variants in macaques.

Since the outbreak of the coronavirus disease (COVID) pandemic in 2019, the development of effective vaccines to combat the infection has been accelerated. With the recent emergence of highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC), there are concerns regarding the immune escape from vaccine-induced immunity. Hence an effective vaccine against VOC with a potent immune response is required. Our previous study confirmed that the two doses of the plant-produced receptor-binding domain (RBD) of SARS-CoV-2 fused with the Fc region of human IgG1, namely Baiya SARS-CoV-2 Vax 1, showed high immunogenicity in mice and monkeys. Here, we aimed to evaluate the immunogenicity of a three-dose intramuscular injection of Baiya SARS-CoV-2 Vax 1 on days 0, 21, and 133 in cynomolgus monkeys. At 14 days after immunization, blood samples were collected to determine RBD-specific antibody titer, neutralizing antibody, and pseudovirus neutralizing antibody titers. Immunized monkeys developed significantly high levels of antigen-specific antibodies against SARS-CoV-2 compared to the control group. Interestingly, the sera collected from immunized monkeys also showed a neutralizing antibody response against the SARS-CoV-2 VOCs; Alpha, Beta, Gamma, Delta, and Omicron. These findings demonstrate that a three-dose regimen of Baiya SARS-CoV-2 Vax 1 vaccine elicits neutralizing immune response against SARS-CoV-2 variants.

Design, construction and in vivo functional assessment of a hinge truncated sFLT01.

Gene therapy for the treatment of ocular neovascularization has reached clinical trial phases. The AAV2-sFLT01 construct was already evaluated in a phase 1 open-label trial administered intravitreally to patients with advanced neovascular age-related macular degeneration. SFLT01 protein functions by binding to VEGF and PlGF molecules and inhibiting their activities simultaneously. It consists of human VEGFR1/Flt-1 (hVEGFR1), a polyglycine linker, and the Fc region of human IgG1. The IgG1 upper hinge region of the sFLT01 molecule makes it vulnerable to radical attacks and prone to causing immune reactions. This study pursued two goals: (i) minimizing the immunogenicity and vulnerability of the molecule by designing a truncated molecule called htsFLT01 (hinge truncated sFLT01) that lacked the IgG1 upper hinge and lacked 2 amino acids from the core hinge region; and (ii) investigating the structural and functional properties of the aforesaid chimeric molecule at different levels (in silico, in vitro, and in vivo). Molecular dynamics simulations and molecular mechanics energies combined with Poisson-Boltzmann and surface area continuum solvation calculations revealed comparable free energy of binding and binding affinity for sFLT01 and htsFLT01 to their cognate ligands. Conditioned media from human retinal pigment epithelial (hRPE) cells that expressed htsFLT01 significantly reduced tube formation in HUVECs. The AAV2-htsFLT01 virus suppressed vascular development in the eyes of newborn mice. The htsFLT01 gene construct is a novel anti-angiogenic tool with promising improvements compared to existing treatments.

A novel probe to assess cytosolic entry of exogenous proteins

Dendritic cells use a specialized pathway called cross-presentation to activate CD8+ T cells by presenting peptides from exogenous protein antigens on major histocompatibility complex class I molecules. Considerable evidence suggests that internalized antigens cross endocytic membranes to access cytosolic proteasomes for processing. The mechanism of protein dislocation represents a major unsolved problem. Here we describe the development of a sensitive reporter substrate, an N-glycosylated variant of Renilla luciferase fused to the Fc region of human IgG1. The luciferase variant is designed to be enzymatically inactive when glycosylated, but active after the asparagine to aspartic acid conversion that occurs upon deglycosylation by the cytosolic enzyme N-glycanase-1. The generation of cytosolic luminescence depends on internalization, deglycosylation, the cytosolic AAA-ATPase VCP/p97, and the cytosolic chaperone HSP90. By incorporating a T cell epitope into the fusion protein, we demonstrate that antigen dislocation into the cytosol is the rate-limiting step in cross-presentation. Currently, we are using this novel probe to determine the efficiency of the cytosolic entry of nanoparticles that co-encapsulate ddRLuc-Fc and mRNA. It will provide us with important information about mRNA delivery by those nanoparticles, potentially leading to a breakthrough in mRNA vaccine development.

TTI-621-03: A phase I/II study of TTI-621 in combination with doxorubicin in patients with unresectable or metastatic high-grade leiomyosarcoma (LMS).

TPS11593 Background: Doxorubicin is a standard of care agent for patients with advanced soft tissue sarcoma, with a response rate of around 15%, progression-free survival of 5-7 months and cumulative cardiac toxicity that limits its use. TTI-621 is a recombinant soluble fusion protein that combines the N-terminal portion of human SIRPα (the binding domain for CD47) with the Fc region of human IgG1, generating a decoy receptor for CD47 on the surface of tumor cells that both over-rides CD47-mediated inhibition of phagocytosis and provides a pro-phagocytic stimulation. Many solid tumors express high levels of CD47 which is associated with poor prognosis, thought to be the result of CD47-mediated inhibition of macrophage phagocytosis and escape of immune-mediated clearance. Interruption of the CD47-SIRPα signaling pathway using monoclonal antibodies to CD47 has shown anti-tumor activity in animal models and in some early clinical trials. The combination of doxorubicin with CD47-targeted antibodies results in enhanced anti-tumor activity and increased macrophage-mediated cell killing in animal models and macrophage-mediated phagocytosis of cancer cell lines in vitro, suggesting that combining TTI-621 with doxorubicin might be more effective than doxorubicin alone in tumor types that express CD47 and have high numbers of macrophages, such as LMS. Thus, a Phase 1/2 study was initiated to evaluate this combination in patients with advanced soft tissue sarcoma, including LMS. Methods: TTI-621-03 is a Phase 1/2, open-label study of TTI-621 in combination with doxorubicin in patients with anthracycline-naïve disease. The Phase 1 dose escalation evaluates doses of TTI-621 (0.2 to 2.0 mg/kg) in combination with doxorubicin at 75 mg/m2 in patients with high-grade soft tissue sarcomas. Expansion cohorts will evaluate TTI-621 (0.2 and 2.0 mg/kg) with doxorubicin in patients with LMS, with pathology confirmed at a central laboratory. The primary goals of this study are evaluation of safety of TTI-621 administered in combination with standard-of-care doxorubicin and to further evaluate clinical activity (ORR, PFS, OS), safety, PK and patient-reported quality of life in the LMS subpopulation. The dose escalation portion of the study has been completed without DLT. Enrollment to the expansion portion of the study is underway. Clinical trial information: NCT04996004.

A single injection of CM1021, a long half-life hepatocyte growth factor mimetic, increases liver mass in mice

Despite years of positive animal data, hepatocyte growth factor (HGF) has never been developed into a useful pharmaceutical, primarily due to its poor pharmacological properties. CM1021 is a fusion protein containing the K1 loop of HGF and the human IgG1 Fc region. The experiments described here demonstrate that CM1021 has the biological properties of HGF and the pharmacological properties of a monoclonal antibody. CM1021 stimulates scattering and branching morphogenesis in MDCK cells and stimulates liver growth in vivo. Unlike HGF, it is available via intraperitoneal injection and has an estimated half-life similar to an antibody.

Addition of an Fc-IgG induces receptor clustering and increases the in vitro efficacy and in vivo anti-tumor properties of the thrombospondin-1 type I repeats (3TSR) in a mouse model of advanced stage ovarian cancer

ObjectivesTumor vasculature is structurally abnormal, with anatomical deformities, reduced pericyte coverage and low tissue perfusion. As a result of this vascular dysfunction, tumors are often hypoxic, which is associated with an aggressive tumor phenotype, and reduced delivery of therapeutic compounds to the tumor. We have previously shown that a peptide containing the thrombospondin-1 type I repeats (3TSR) specifically targets tumor vessels and induces vascular normalization in a mouse model of epithelial ovarian cancer (EOC). However, due to its small size, 3TSR is rapidly cleared from circulation. We now introduce a novel construct with the 3TSR peptide fused to the C-terminus of each of the two heavy chains of the Fc region of human IgG1 (Fc3TSR). We hypothesize that Fc3TSR will have greater anti-tumor activity in vitro and in vivo compared to the native compound. MethodsFc3TSR was evaluated in vitro using proliferation and apoptosis assays to investigate differences in efficacy compared to native 3TSR. In light of the multivalency of Fc3TSR, we also investigate whether it induces greater clustering of its functional receptor, CD36. We also compare the compounds in vivo using an orthotopic, syngeneic mouse model of advanced stage EOC. The impact of the two compounds on changes to tumor vasculature morphology was also investigated. ResultsFc3TSR significantly decreased the viability and proliferative potential of EOC cells and endothelial cells in vitro compared to native 3TSR. High-resolution imaging followed by image correlation spectroscopy demonstrated enhanced clustering of the CD36 receptor in cells treated with Fc3TSR. This was associated with enhanced downstream signaling and greater in vitro and in vivo cellular responses. Fc3TSR induced greater vascular normalization and disease regression compared to native 3TSR in an orthotopic, syngeneic mouse model of advanced stage ovarian cancer. ConclusionThe development of Fc3TSR which is greater in size, stable in circulation and enhances receptor activation compared to 3TSR, facilitates its translational potential as a therapy in the treatment of metastatic advanced stage ovarian cancer.

Updates from Ongoing, First-in-Human Phase 1 Dose Escalation and Expansion Study of TTI-621, a Novel Biologic Targeting CD47, in Patients with Relapsed or Refractory Hematologic Malignancies

Updates from Ongoing, First-in-Human Phase 1 Dose Escalation and Expansion Study of TTI-621, a Novel Biologic Targeting CD47, in Patients with Relapsed or Refractory Hematologic Malignancies

CD69 mediates the protective role of adipose tissue-derived mesenchymal stem cells against Pseudomonas aeruginosa pulmonary infection.

BackgroundOur previous study shows that Adipose tissue‐derived mesenchymal stem cells (ASCs) are a promising strategy for cell‐based therapy against pulmonary infection with Pseudomonas aeruginosa (P. aeruginosa), but the underlying mechanisms remain unclear.MethodscDNA microarray assay was performed to explore the transcriptome of ASCs primed by P. aeruginosa. Small interfering RNA (siRNA) was constructed to select the receptor candidates for P. aeruginosa recognition and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) production in ASCs. The soluble protein chimeras containing the extracellular domain of human CD69 fused to the Fc region of human immunoglobulin IgG1 were used as a probe to validate the recognition of P. aeruginosa. The association between CD69 and extracellular regulated protein kinases 1/2 (ERK1/2) was explored via co‐immunoprecipitation, siRNA, and inhibitor. The murine models of P. aeruginosa pneumonia treated with WT‐ASCs, GM‐CSF −/−‐ASCs Cd69 −/−‐ASCs or Erk1 −/−‐ASCs were used to determine the role of GM‐CSF, CD69, and ERK1 in ASCs against P. aeruginosa infection.ResultsWe showed that C‐type lectin receptor CD69 mediated the protective effects of ASCs partly through GM‐CSF. CD69 could specifically recognize P. aeruginosa and regulate GM‐CSF secretion of ASCs. CD69 regulated the production of GM‐CSF via ERK1 in ASCs after P. aeruginosa infection. Moreover, the Administration of ASCs with deficiency of CD69 or ERK1 completely blocked its protective effects in a murine model of P. aeruginosa pneumonia.ConclusionsCD69 recognizes P. aeruginosa and further facilitates ERK1 activation, which plays a crucial role in ASCs‐based therapy against P. aeruginosa pneumonia. CD69 may be a novel target molecule to improve ASCs‐based therapy against P. aeruginosa infection.

Potent Neutralizing Antibodies Elicited by RBD-Fc-Based COVID-19 Vaccine Candidate Adjuvanted by the Th2-Skewing iNKT Cell Agonist.

The development of a safe and effective COVID-19 vaccine is of paramount importance to terminate the current pandemic. An adjuvant is crucial for improving the efficacy of the subunit COVID19 vaccine. α-Galactosylceramide (αGC) is a classical iNKT cell agonist which causes the rapid production of Th1- and Th2-associated cytokines; we, therefore, expect that the Th1- or Th2-skewing analogues of αGC can better enhance the immunogenicity of the receptor-binding domain in the spike protein of SARS-CoV-2 fused with the Fc region of human IgG (RBD-Fc). Herein, we developed a universal synthetic route to the Th1-biasing (α-C-GC) and Th2-biasing (OCH and C20:2) analogues. Immunization of mice demonstrated that αGC-adjuvanted RBD-Fc elicited a more potent humoral response than that observed with Alum and enabled the sparing of antigens. Remarkably, at a low dose of the RBD-Fc protein (2 μg), the Th2-biasing agonist C20:2 induced a significantly higher titer of the neutralizing antibody than that of Alum.

German S3-Guideline on the treatment of Psoriasis vulgaris, adapted from EuroGuiDerm - Part 2: Treatment monitoring and specific clinical or comorbid situations.

German S3-Guideline on the treatment of Psoriasis vulgaris, adapted from EuroGuiDerm - Part 2: Treatment monitoring and specific clinical or comorbid situations.

TTI-621 (SIRPαFc), an Immune Checkpoint Inhibitor Blocking the CD47 “Do Not Eat” Signal, Induces Objective Responses in Patients with Advanced, Relapsed/Refractory Diffuse Large B-Cell Lymphoma (DLBCL)

BackgroundCD47 is an immune checkpoint that binds to signal regulatory protein alpha (SIRPα) and delivers a “do not eat” signal to suppress macrophage phagocytosis. Tumor cells frequently overexpress CD47 to evade macrophage-mediated destruction. TTI-621 (SIRPαFc) is an immune checkpoint inhibitor consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1 designed to both: 1) block the CD47 “do not eat” signal, and 2) engage macrophage Fcγ receptors with IgG1 Fc to enhance phagocytosis and antitumor activity.MethodsA phase 1, open-label, multicenter study is ongoing to evaluate the activity of weekly IV infusions of TTI-621 in multiple cohorts of adult patients (pts) with relapsed or refractory malignancies. Eligible pts are those who have progressed on standard anticancer therapy (including rituximab for pts with B-cell lymphomas), or those for whom no other approved therapy exists (NCT02663518). This data disclosure comprises all consecutively enrolled pts with diffuse large B-cell lymphoma (DLBCL) who received, at a minimum, 0.2 mg/kg/week TTI-621 monotherapy or 0.1 mg/kg TTI-621 in combination with 375 mg/m2/week rituximab for 8 weeks, after which TTI-621 monotherapy was permitted.ResultsAs of June 1, 2017, 14 evaluable pts with DLBCL (7M/7F, age 42-72 years) have been enrolled and treated: 6 pts received TTI-621 monotherapy and 8 pts received TTI-621 plus rituximab. The number of prior systemic therapies ranged from 2 to 13; 6 pts had received prior autograft. Weekly outpatient treatments have been well tolerated. Mild-to-moderate infusion-related reactions were experienced by 9 pts following the first dose of TTI-621. Transient, dose-dependent decreases in platelets and leukocytes were generally without clinical sequelae. Objective responses were observed for 5/14 pts (36%): 1/6 pts treated with TTI-621 monotherapy and 4/8 pts treated with TTI-621 plus rituximab. Two pts attained complete responses (CR). One CR occurred in a pt treated with TTI-621 monotherapy who remains in continued CR at 20+ weeks. The second CR was in a pt treated with TTI-621 plus rituximab who remains in continued CR at 12+ weeks.ConclusionsWeekly IV dosing employing TTI-621 to block the CD47 “do not eat” signal as monotherapy or in combination with rituximab was well tolerated. Treatment was associated with preliminary and promising anti-tumor activity in pts with advanced DLBCL as evidenced by 2 CRs and 3 PRs among 14 pts. DisclosuresAnsell:Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Merck: Research Funding; Celldex: Research Funding; Seattle Genetics: Research Funding. Flinn:Genentech: Research Funding; Janssen: Research Funding; Janssen: Research Funding; Acerta: Research Funding; AbbVie Company: Research Funding; Seattle Genetics: Research Funding; KITE: Research Funding; Verastem: Research Funding; Curis: Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; Agios: Research Funding; Beigene: Research Funding; Forty Seven: Research Funding; Pfizer: Research Funding; Merck: Research Funding; Pharmacyclics: Research Funding; Incyte: Research Funding; Gilead: Research Funding; Novartis: Research Funding; Constellation: Research Funding; Celgene: Research Funding; Pharmacyclics LLC: Research Funding; Takeda: Research Funding; Portola: Research Funding; Trillium: Research Funding; Calithera: Research Funding. O'Connor:Celgene: Honoraria, Research Funding; Trillium Therapeutics: Research Funding. Advani:Pfizer: Consultancy; Takeda/ Millenium: Research Funding. Percival:FLXbio: Research Funding. Johnson:Trillium Therapeutics: Employment. Catalano:Trillium Therapeutics: Employment; Apotex Inc.: Employment. Irwin:Hoffmann La Roche: Employment, Equity Ownership; Trillium Therapeutics: Employment, Equity Ownership. Petrova:Trillium Therapeutics: Employment, Equity Ownership. Uger:Trillium Therapeutics: Employment, Equity Ownership, Patents & Royalties. Sievers:Trillium Therapeutics: Employment, Equity Ownership. Chen:Genentech: Speakers Bureau; Merck: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding; Pfizer: Consultancy; Pharmacyclics: Consultancy, Research Funding; Affimed: Research Funding.

A Single Direct Intratumoral Injection of TTI-621 (SIRPαFc) Induces Antitumor Activity in Patients with Relapsed/Refractory Mycosis Fungoides and Sézary Syndrome: Preliminary Findings Employing an Immune Checkpoint Inhibitor Blocking the CD47 “Do Not Eat” Signal

BackgroundCD47 is an immune checkpoint that binds to signal regulatory protein alpha (SIRPα) and delivers a “do not eat” signal to suppress macrophage phagocytosis. Tumor cells frequently overexpress CD47 to evade macrophage-mediated destruction. TTI-621 (SIRPαFc) is an immune checkpoint inhibitor consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1 designed to both: 1) block the CD47 “do not eat” signal, and 2) engage macrophage Fcγ receptors with IgG1 Fc to enhance phagocytosis and antitumor activity. It is hypothesized that direct intratumoral injection of TTI-621 may enhance both local and systemic antitumor activity.MethodsA Phase 1, multicenter, open-label study is ongoing to characterize the safety and tolerability of intratumoral injection of TTI-621 (NCT02890368). Eligible patients (pts) are adults with relapsed or refractory mycosis fungoides/Sézary syndrome or percutaneously-accessible solid tumors who have progressed on standard anticancer therapy or for whom no other approved therapy exists. Pts are enrolled in sequential cohorts to receive a single intratumoral injection of TTI-621 at increasing dose levels to characterize safety, pharmacokinetics, pharmacodynamics, and preliminary evidence of antitumor activity. Repeat TTI-621 intratumoral dosing has recently been initiated. Serial, post-injection biopsies are collected to assess the temporal impact of TTI-621 on the tumor microenvironment.ResultsNine pts (6 M/3F, age 57-85 years) have been enrolled as of July 2017. Diagnoses include mycosis fungoides/Sézary syndrome (N=6), melanoma (N=1), leiomyosarcoma (N=1), and squamous cell carcinoma (N=1). A single intratumoral injection of 1 mg, 3 mg, or 10 mg TTI-621 has been well tolerated by all enrolled pts. The most frequently reported adverse events were fatigue in 5 pts, chills in 4 pts, and decreased appetite in 3 pts. All treatment-related AEs were Grade 1 or 2 in severity. No dose limiting toxicity has been observed to date. All 6 pts with mycosis fungoides/Sézary syndrome experienced decreases in tumor size and/or decreased circulating Sézary cells (3 of 3 pts) as determined by a decrease in a peripheral clonal T-cell populationor CD4:CD8 ratio after a single intratumoral injection of TTI-621. Responses ranged from loco-regional to systemic effects. One pt with localized refractory mycosis fungoides on the dorsum of the foot obtained a complete response of the injected lesion that is ongoing after 17+ weeks of follow up. NanoString analysis of peripheral blood and tumor tissue pre- and post-intratumoral injection of TTI-621 indicated alterations in genes associated with activation of the innate immune system and upregulation of IFN-associated genes.ConclusionsThese preliminary Phase 1 data suggest that mycosis fungoides and its leukemic variant, Sézary syndrome, are highly responsive to a single dose of TTI-621 delivered by intratumoral injection. One pt achieved a complete response of the injected lesion and 5 additional pts experienced decreases in tumor size and/or decreased circulating Sézary cells. Intratumoral injections were well tolerated by all pts. Evidence of innate immune activation was documented, consistent with the proposed function of TTI-621 as an innate immune checkpoint inhibitor. DisclosuresQuerfeld:Soligenix: Research Funding; Elorac: Research Funding; Celgene: Honoraria, Research Funding; MiRagen: Honoraria, Research Funding; Actelion: Honoraria, Research Funding; Medivir: Honoraria; Mallinckrodt: Honoraria; Mindera: Consultancy; Kyowa: Research Funding; Trillium Therapeutics: Research Funding; City of Hope: Employment. Thompson:Trillium Therapeutics: Research Funding. Taylor:Blue Print Medicines: Consultancy, Honoraria; Eisai Inc.: Consultancy, Honoraria, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Speakers Bureau; Trillium Therapeutics: Consultancy, Honoraria. Pillai:Trillium Therapeutics: Research Funding. Johnson:Trillium Therapeutics: Employment. Catalano:Trillium Therapeutics: Employment; Apotex Inc.: Employment. Petrova:Trillium Therapeutics: Employment, Equity Ownership. Uger:Trillium Therapeutics: Employment, Equity Ownership, Patents & Royalties. Irwin:Hoffmann La Roche: Employment, Equity Ownership; Trillium Therapeutics: Employment, Equity Ownership. Sievers:Trillium Therapeutics: Employment, Equity Ownership. Akilov:Seattle Genetics: Consultancy; Medivir: Consultancy; Actelion Pharmacuticals: Consultancy, Research Funding; Trillium Therapeutics: Research Funding.