Fc Fusion Research Articles

A first-in-human, randomized study of the safety, pharmacokinetics and pharmacodynamics of povetacicept, an enhanced dual BAFF/APRIL antagonist, in healthy adults.

Therapeutic agents targeting the tumor necrosis factor (TNF) superfamily cytokines B-cell activating factor (BAFF, BLyS) and/or A PRoliferation Inducing Ligand (APRIL) have demonstrated clinical effectiveness in multiple autoimmune diseases, such as systemic lupus erythematosus, lupus nephritis, and immunoglobulin A nephropathy (IgAN). However, their clinical utility can often be limited by incomplete and/or prolonged times to clinical response and inconvenient dosing regimens, which may be improved by more potent dual inhibition of both cytokines. Povetacicept (ALPN-303; TACI vTD-Fc) is a crystallizable fragment (Fc) fusion protein of an engineered transmembrane activator and CAML interactor (TACI) domain which mediates more potent inhibitory activity than wild-type TACI-Fc or BAFF- or APRIL-specific antibodies and demonstrates superior pharmacokinetic and pharmacodynamic activity in multiple preclinical disease models. In this first-in-human study in healthy adults, povetacicept was well-tolerated as single ascending doses of up to 960 mg administered intravenously or subcutaneously. Dose-dependent pharmacokinetics were observed. Coverage of BAFF and APRIL was observed for 2-3 weeks and ≥4 weeks after doses of 80 mg and ≥240 mg, respectively. Maximal pharmacodynamic effects were observed at dose levels ≥80 mg for a single dose, associated with on-target reductions in antibody-secreting cells as well as in all circulating immunoglobulin isotypes, including the IgAN disease-related biomarker galactose-deficient-immunoglobulin A1 (Gd-IgA1), and were superior to results reported for wild-type TACI-Fc. These data strongly support further development of povetacicept for the treatment of B-cell-mediated automimmune diseases.

Superior Prophylactic Effectiveness of a Recombinant FVIIIFc Over Standard Half-Life FVIII in Hemophilia A: A-SURE Study.

The 24-month, prospective, non-interventional, European multicenter A-SURE study evaluated the real-world effectiveness of prophylaxis using an extended half-life recombinant factor VIII (FVIII) Fc fusion protein, efmoroctocog alfa (hereinafter rFVIIIFc), compared with prophylaxis using standard half-life (SHL) FVIII products in patients with hemophilia A. Primary endpoints were annualized bleeding rate (ABR), annualized injection frequency, and annualized factor consumption. A comparative study design unique for an observational hemophilia study was implemented to reduce potential confounding in effectiveness estimates, wherein each patient prescribed rFVIIIFc was matched with one receiving SHL FVIII. Propensity scores were used for adjustment in statistical analyses. Outcomes for all primary endpoints were significantly better in the rFVIIIFc group (n = 184) compared with the SHL FVIII group (n = 170): mean ABR 1.5 versus 2.3 (difference of -0.8; p = 0.0147); mean annualized injection frequency 114.4 versus 169.2 (difference of -54.8; p < 0.0001); and mean annualized factor consumption 243 024.2 versus 288 718.6 International Units (difference of 45 694.5; p = 0.0003). rFVIIIFc was well tolerated, with no inhibitor development. rFVIIIFc has superior prophylactic effectiveness versus SHL FVIII, providing higher bleed protection with fewer injections and lower factor consumption.

PBPK modeling of recombinant factor IX Fc fusion protein (rFIXFc) and rFIX to characterize the binding to type 4 collagen in the extravascular space.

Patients with severe and sometimes moderate hemophilia B are prophylactically treated with factor IX concentrates to prevent bleeding. For some time now, various extended terminal half-life (EHL) recombinant factor IX concentrates are available allowing less frequent administration during prophylaxis in comparison to standard half-life recombinant FIX (rFIX). Especially, recombinant FIX-Fc fusion protein (rFIXFc; Alprolix®) exhibits a rapid distribution phase, potentially due to binding to type IV collagen (Col4) in the extravascular space. Studies suggest that the presence of extravascular rFIXFc is protective against bleeding as without measurable FIX activity in plasma, and no extra bleeding seems to occur. The physiologically based pharmacokinetic (PBPK) model for rFIXFc which we describe in this study, is able to accurately predict the observed concentration-time profiles of rFIXFc in plasma and is able to quantify the binding of rFIXFc to Col4 in the extravascular space after an intravenous dose of 50 IU/kg rFIXFc in a male population. Our model predicts that the total AUC of rFIXFc bound to Col4 in the extravascular space is approximately 19 times higher compared to the AUC of rFIXFc in plasma. This suggests that rFIXFc present in the extravascular compartment may play an important role in achieving hemostasis after rFIXFc administration. Further studies on extravascular distribution of rFIXFc and the distribution profile of other EHL-FIX concentrates are needed to evaluate the predictions of our PBPK model and to investigate its clinical relevance.

50617 Activated Regulatory T Cells with a Highly Immunosuppressive Phenotype are Expanded by XmAb564, a Novel Potency-Optimized IL-2 Fc Fusion Protein

50617 Activated Regulatory T Cells with a Highly Immunosuppressive Phenotype are Expanded by XmAb564, a Novel Potency-Optimized IL-2 Fc Fusion Protein

A Novel Tetravalent CD95/Fas Fusion Protein With Superior CD95L/FasL Antagonism.

Inhibition of CD95/Fas activation is currently under clinical investigation as a therapy for glioblastoma multiforme and preclinical studies suggest that disruption of the CD95-CD95L interaction could also be a strategy to treat inflammatory and neurodegenerative disorders. Besides neutralizing anti-CD95L/FasL antibodies, mainly CD95ed-Fc, a dimeric Fc fusion protein of the extracellular domain of CD95 (CD95ed), is used to prevent CD95 activation. In view of the fact that full CD95 activation requires CD95L-induced CD95 trimerization and clustering of the resulting liganded CD95 trimers, we investigated whether fusion proteins of the extracellular domain of CD95 with a higher valency than CD95ed-Fc have an improved CD95L-neutralization capacity. We evaluated an IgG1(N297A)-based tetravalent CD95ed fusion protein which was obtained by replacing the variable domains of IgG1(N297A) with CD95ed (CD95ed-IgG1(N297A)) and a hexavalent variant obtained by fusion of CD95ed with a TNC-Fc(DANA) scaffold (CD95ed-TNC-Fc(DANA)) promoting hexamerization. The established N297A and DANA mutations were used to minimize FcγR binding of the constructs under maintenance of neonatal Fc receptor (FcRn) binding. Size exclusion high-performance liquid chromatography indicated effective assembly of CD95ed-IgG1(N297A). More important, CD95ed-IgG1(N297A) was much more efficient than CD95ed-Fc in protecting cells from cell death induction by human and murine CD95L. Surprisingly, despite its hexavalent structure, CD95ed-TNC-Fc(DANA) displayed an at best minor improvement of the capacity to neutralize CD95L suggesting that besides valency, other factors, such as spatial organization and agility of the CD95ed domains, play also a role in neutralization of CD95L trimers by CD95ed fusion proteins. More studies are now required to evaluate the superior CD95L-neutralizing capacity of CD95ed-IgG1(N297A) in vivo.

Physiologically based pharmacokinetic models for systemic disposition of protein therapeutics in rabbits.

Physiologically based pharmacokinetic (PBPK) modelling is an important tool to predict drug disposition in the body. Rabbits play a pivotal role as a highly valued small animal model, particularly in the field of ocular therapeutics, where they serve as a crucial link between preclinical research and clinical applications. In this context, we have developed PBPK models designed specifically for rabbits, with a focus on accurately predicting the pharmacokinetic profiles of protein therapeutics following intravenous administration. Our goal was to comprehend the influence of key physiological factors on systemic disposition of antibodies and their functional derivatives. For the development of the systemic PBPK models, rabbit physiological factors such as gene expression, body weight, neonatal fragment crystallizable receptor (FcRn) binding, target binding, target concentrations, and target turnover rate were meticulously considered. Additionally, key protein parameters, encompassing hydrodynamic radius, binding kinetic constants (KD, koff), internal degradation of the protein-target complex, and renal clearance, were represented in the models. Our final rabbit models demonstrated a robust correlation between predicted and observed serum concentration-time profiles after single intravenous administration in rabbits, covering IgG, Fab, F(ab)2, Fc, and Fc fusion proteins from various publications. These pharmacokinetic simulations offer a promising platform for translating preclinical findings to clinical settings. The presented rabbit intravenous PBPK models lay an important foundation for more specific applications of protein therapeutics in ocular drug development.

Transplacental delivery of factor IX Fc-fusion protein ameliorates bleeding phenotype of newborn hemophilia B mice

Hemophilia B is an inherited hemorrhagic disorder characterized by a deficiency of blood coagulation factor IX (FIX) that results in abnormal blood coagulation. The blood coagulation is already evident in hemophiliacs at the fetal stage, and thus intracranial hemorrhage and other bleeding complications can occur at birth, leading to sequelae. Therefore, it is important to develop effective treatments for hemophiliacs in utero. In this study, in order to transplacentally deliver FIX from pregnant mice to their fetuses, an improved adenovirus (Ad) vector expressing human FIX fused with the IgG Fc domain (FIX Fc fusion protein), which plays a crucial role in neonatal Fc receptor (FcRn)-mediated transcytosis across the placenta, was intravenously administered to E13.5 pregnant mice. Significant levels of FIX Fc fusion protein were detected in 0-day-old newborn mice whose mothers were administered an Ad vector expressing FIX Fc fusion protein. Wild-type FIX overexpressed in the pregnant mice was not delivered to the fetuses. Plasma FIX levels in the newborn mice were relatively well correlated with those in their mothers, although transplacental delivery efficiencies of FIX Fc fusion protein were slightly reduced when the FIX Fc fusion protein was highly expressed in the mother mice. Plasma FIX levels in the newborn mice were about 3.6–6.4% of those in their mothers, Transplacental delivery of FIX Fc fusion protein to their fetuses successfully improved the blood clotting ability in the newborn mice.

Pigment Epithelium-Derived Factor Binding to VEGFR-1 (Flt-1) Increases the Survival of Retinal Neurons.

The purpose of this study was to examine possible involvement of vascular endothelial growth factor (VEGF) receptor (VEGFR)-1/Flt-1 in pigment epithelium-derived factor (PEDF)-promoted survival of retinal neurons. Survival of growth factor-deprived retinal ganglion cells (RGCs) and R28 cells and activation of ERK-1/-2 MAP kinases were assessed in the presence of PEDF, placental growth factor (PlGF), and VEGF using cell cultures, viability assays and quantitation of ERK-1/-2 phosphorylation. VEGFR-1/Flt-1 expression was determined using quantitative PCR (qPCR) and Western blotting. VEGFR-1/Flt-1 was knocked down in R28 cells by small interfering RNA (siRNA). Binding of a PEDF-IgG Fc fusion protein (PEDF-Fc) to retinal neurons, immobilized VEGFR-1/Flt-1 and VEGFR-1/Flt-1-derived peptides was studied using binding assays and peptide scanning. PEDF in combination with PlGF stimulated increased cell survival and ERK-1/-2 MAP kinase activation compared to effects of either factor alone. VEGFR-1/Flt-1 expression in RGCs and R28 cells was significantly upregulated by hypoxia, VEGF, and PEDF. VEGFR-1/Flt-1 ligands (VEGF and PlGF) or soluble VEGFR-1 (sflt-1) competed with PEDF-Fc for binding to R28 cells. Depleting R28 cells of VEGFR-1/Flt-1 resulted in reduced PEDF-Fc binding when comparing VEGFR-1/Flt-1 siRNA- and control siRNA-treated cells. PEDF-Fc interacted with immobilized sflt-1, which was specifically blocked by VEGF and PlGF. PEDF-Fc binding sites were mapped to VEGFR-1/Flt-1 extracellular domains D3 and D4. Peptides corresponding to D3 and D4 specifically inhibited PEDF-Fc binding to R28 cells. These peptides and sflt-1 significantly inhibited PEDF-promoted survival of R28 cells. These results suggest that PEDF can target VEGFR-1/Flt-1 and this interaction plays a significant role in PEDF-mediated neuroprotection in the retina.

IOS-1002, a Stabilized HLA-B57 Open Format, Exerts Potent Anti-Tumor Activity.

HLA-B27 and HLA-B57 are associated with autoimmunity and long-term viral control and protection against HIV and HCV infection; however, their role in cancer immunity remains unknown. HLA class I molecules interact with innate checkpoint receptors of the LILRA, LILRB and KIR families present in diverse sets of immune cells. Here, we demonstrate that an open format (peptide free conformation) and expression- and stability-optimized HLA-B57-B2m-IgG4_Fc fusion protein (IOS-1002) binds to human leukocyte immunoglobulin-like receptor B1 and B2 (LILRB1 and LILRB2) and to killer immunoglobulin-like receptor 3DL1 (KIR3DL1). In addition, we show that the IgG4 Fc backbone is required for engagement to Fcγ receptors and potent activation of macrophage phagocytosis. IOS-1002 blocks the immunosuppressive ITIM and SHP1/2 phosphatase signaling cascade, reduces the expression of immunosuppressive M2-like polarization markers of macrophages and differentiation of monocytes to myeloid-derived suppressor cells, enhances tumor cell phagocytosis in vitro and potentiates activation of T and NK cells. Lastly, IOS-1002 demonstrates efficacy in an ex vivo patient-derived tumor sample tumoroid model. IOS-1002 is a first-in-class multi-target and multi-functional human-derived HLA molecule that activates anti-tumor immunity and is currently under clinical evaluation.

Phase I studies of davoceticept (ALPN-202), a PD-L1-dependent CD28 co-stimulator and dual PD-L1/CTLA-4 inhibitor, as monotherapy and in combination with pembrolizumab in advanced solid tumors (NEON-1 and NEON-2)

BackgroundDavoceticept (ALPN-202) is an Fc fusion of a CD80 variant immunoglobulin domain designed to mediate programmed death-ligand 1 (PD-L1)-dependent CD28 co-stimulation while inhibiting the PD-L1 and cytotoxic T-lymphocyte-associated antigen 4...

The process using a synthetic library that generates multiple diverse human single domain antibodies.

Single domain antibodies (sdAbs) possess unique characteristics that make them highly effective for developing complex therapeutics. Our process uses a fully synthetic phage display library to generate single domain antibodies that can bind to disease relevant antigen conformations. A human IGHV3 family scaffold makes up the phage display libraries, and these VHO libraries are applied to diverse phage biopannings against target antigens. After NGS processing, unique VHOs undergo automated cloning into expression constructs followed by transfections and purifications. Binding assays were used to determine VHO binding behaviors to the target proteins. Additional VHO interactions are measured against endogenous targets on cells by way of flow cytometry, cell internalization, and activation assays. We show that a fully synthetic phage display library can generate VHOs that bind to disease relevant antigen conformations. The diverse biopanning methods and processing of next-generation sequencing generated many VHO paratopes. These different VHO sequences can be expressed as Fc fusion proteins. Various screening assays resulted in VHOs representing different epitopes or activities. During the hit evaluation, we demonstrate how screening can identify distinct VHO activities that have been used to generate differentiated drug molecules in various bispecific and multispecific antibody formats. We demonstrate how screening can identify distinct VHO activities that have been used to generate differentiated drug molecules in various bispecific and multispecific antibody formats.

Pre-Clinical Studies of a Novel Bispecific Fusion Protein Targeting C3b and VEGF in Neovascular and Nonexudative AMD Models.

KNP-301 is a bi-specific fragment crystallizable region (Fc) fusion protein, which inhibits both C3b and vascular endothelial growth factor (VEGF) simultaneously for patients with late-stage age-related macular degeneration (AMD). The present study evaluated in vitro potency, in vivo efficacy, intravitreal pharmacokinetics (IVT PK), and injectability of KNP-301. C3b and VEGF binding of KNP-301 were assessed by surface plasmon resonance (SPR) and enzyme-linked immunosorbent assay (ELISA), and cellular bioassays. A laser-induced choroidal neovascularization (CNV) model and a sodium iodate-induced nonexudative AMD model were used to test the in vivo efficacy of mouse surrogate of KNP-301. Utilizing fluorescein angiography (FA) and spectral-domain optical coherence tomography (SD-OCT) scans, the reduction in disease lesions were analyzed in a CNV mouse model. In the nonexudative AMD mouse model, outer nuclear layer (ONL) was assessed by immunofluorescence staining. Lastly, intravitreal pharmacokinetic study was conducted with New Zealand white rabbits via IVT administration of KNP-301 and injectability of KNP-301 was examined by a viscosity test at high concentrations. KNP-301 bound C3b selectively, which resulted in a blockade of the alternative pathway, not the classical pathway. KNP-301 also acted as a VEGF trap, impeding VEGF-mediate signaling. Our dual-blockade strategy was effective in both neovascular and nonexudative AMD models. Moreover, KNP-301 had an advantage of potentially less frequent dosing due to the long half-life in the intravitreal chamber. Our viscosity assessment confirmed that KNP-301 meets the criteria of the IVT injection. Unlike current therapies, KNP-301 is expected to cover patients with late-stage AMD of both neovascular and nonexudative AMD, and its long-term PK profile at the intravitreal chamber would allow convenience in the dosing interval of patients.

Pharmacokinetics, pharmacodynamics, and safety of GS-3583, a FLT3 agonist Fc fusion protein, from single-ascending-dose phase I study in healthy participants.

Conventional dendritic cells subtype 1 (cDC1) play a vital role in the priming and expansion of tumor-specific CD8+ T cells and their recruitment to tumor microenvironment. However, cDC1s are often underrepresented in the microenvironment. Systemic administration of Fms-like tyrosine kinase 3 ligand, a hematopoietic growth factor that binds to FLT3 on myeloid and lymphoid progenitor cells, leads to cDC1 expansion in the periphery and recruitment into the microenvironment. FLT3 pathway stimulation using GS-3583, a novel FLT3 agonistic Fc fusion protein, has the potential to promote T-cell mediated antitumor activity. This was a first-in-human, placebo-controlled study of GS-3583 in healthy participants to evaluate the safety, pharmacokinetics (PK), and pharmacodynamic (PD) of escalating single doses (75-2000 μg) of GS-3583. Each dose cohort enrolled 8-12 healthy participants who received GS-3583 or placebo as single IV infusion at 3:1 ratio. As part of the PD evaluation, the changes in the number of cDC1 cells were investigated. GS-3583 was well-tolerated in healthy participants up to the highest evaluated dose (2000 μg). There have been no serious or grade III or higher adverse events. PK analysis suggested a dose-dependent increase in GS-3583 exposure with target-mediated disposition characteristics at low doses. PD analysis shows that administration of GS-3583 resulted in transient, dose-dependent increases in cDC1 cells that returned to baseline within 3 weeks of drug administration. The pharmacokinetics and pharmacodynamics of GS-3583 following single dosing were characterized in this study which enabled subsequent phase Ib assessments in patients with advanced solid tumors.

Long-term clinical outcomes of prophylaxis with an rFVIIIFc or rFIXFc in adults aged ≥50 years with hemophilia A or B

Advances in therapies for hemophilia have led to an increased life expectancy for people with hemophilia. Limited data exist on the aging population of people with hemophilia who face additional challenges of age-related comorbidities. Efmoroctocog alfa (a recombinant factor VIII Fc fusion protein [herein referred to as rFVIIIFc]) and eftrenonacog alfa (a recombinant factor IX Fc fusion protein [rFIXFc]) are extended half-life factor replacements for hemophilia A and B, respectively, with demonstrated long-term safety and efficacy. The objective of this post hoc analysis was to describe long-term outcomes in participants 50+ years of age treated with rFVIIIFc or rFIXFc in pivotal Phase 3 trials and their extension studies: A-LONG (NCT01181128; n=21) and ASPIRE (NCT01454739; n=20 [95%]); B-LONG (NCT01027364; n=26) and B-YOND (NCT01425723; n=16 [62%]). Approximately half of participants (48%) with hemophilia A and 62% of participants with hemophilia B had a comorbidity at baseline. More than half of the participants were taking 1+ concomitant medication at baseline, with arthropathy and joint pain reported as the most common indications. Prophylaxis with rFVIIIFc or rFIXFc in individuals 50+ years of age with hemophilia A or B, respectively, resulted in low annualized bleed rates and improvements in joint health. Positive impacts on health-related quality of life were observed in individuals on either rFVIIIFc or rFIXFc prophylaxis. The results for the older subgroups were consistent with the overall study populations, demonstrating that prophylaxis with rFVIIIFc or rFIXFc provides long-term clinical benefits irrespective of age and presence of target joints in patients with severe hemophilia.

Comparison of the Immunogenicity of the LZ901 Vaccine and HZ/su Vaccine in a Mouse Model.

Herpes zoster (HZ) is an infectious disease caused by the reactivation of varicella zoster virus (VZV), with 68% of cases occurring in adults over 50 years of age. HZ/su (Shingrix®) was approved by the Food and Drug Administration in 2017 for the prevention of HZ in individuals ≥ 50 years of age and showed very good protection from HZ. However, due to the use of the adjuvant AS01B, adverse reactions caused by Shingrix are a concern. Aluminum hydroxide is the most commonly used adjuvant and is widely used in a variety of vaccines. We developed a recombinant zoster vaccine (code: LZ901) consisting of a tetramer of VZV glycoprotein E (gE) and a human Fc fusion protein expressed in CHO cells, an immune complex-like molecule that can be adsorbed with an aluminum hydroxide adjuvant. We compared the immunogenicity of LZ901 with that of HZ/su in BALB/c mice. The results showed that LZ901 induced levels of gE-specific IgG antibodies comparable to those induced by HZ/su, and the results of FAMA titers further demonstrated their similar neutralizing antibody abilities. Most importantly, LZ901 induced higher levels of cell-mediated immunity (CMI) (which plays a decisive role in the efficacy of zoster vaccines) than HZ/su in BALB/c mice. The numbers of cytokine-producing T cells in LZ901-vaccinated mice were significantly greater than those in v-vaccinated mice, and the proportions of CD4+ and CD8+ T cells producing at least two types of cytokines in LZ901-vaccinated mice were significantly greater than those in HZ/su-vaccinated mice.

Combining CD38 antibody with CD47 blockade is a promising strategy for treating hematologic malignancies expressing CD38.

CD38 and CD47 are expressed in many hematologic malignancies, including multiple myeloma (MM), B-cell non-Hodgkin lymphoma (NHL), B-cell acute lymphoblastic leukemia (ALL), and B-cell chronic lymphocytic leukemia (CLL). Here, we evaluated the antitumor activities of CD38/CD47 bispecific antibodies (BsAbs). Five suitable anti-CD38 antibodies for co-targeting CD47 and CD38 BsAb were developed using a 2 + 2 "mAb-trap" platform. The activity characteristics of the CD38/CD47 BsAbs were evaluated using in vitro and in vivo systems. Using hybridoma screening technology, we obtained nine suitable anti-CD38 antibodies. All anti-CD38 antibodies bind to CD38+ tumor cells and kill tumor cells via antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Five anti-CD38 antibodies (4A8, 12C10, 26B4, 35G5, and 65A7) were selected for designing CD38/CD47 BsAbs (IMM5605) using a "mAb-trap" platform. BsAbs had higher affinity and binding activity to the CD38 target than those to the CD47 target, decreasing the potential on-target potential and off-tumor effects. The CD38/CD47 BsAbs did not bind to RBCs and did not induce RBC agglutination; thus, BsAbs had much lower blood toxicity. The CD38/CD47 BsAbs had a greater ability to block the CD47/SIRPα signal in CD38+/CD47+ tumor cells than IMM01 (SIRPα Fc fusion protein). Through Fc domain engineering, CD38/CD47 BsAbs were shown to kill tumors more effectively by inducing ADCC and ADCP. IMM5605-26B4 had the strongest inhibitory effect on cellular CD38 enzymatic activity. IMM5605-12C10 had the strongest ability to directly induce the apoptosis of tumor cells. The anti-CD38 antibody 26B4 combined with the SIRPα-Fc fusion proteins showed strong antitumor effects, which were better than any of the mono-therapeutic agents used alone in the NCI-H929 cell xenograft model. The CD38/CD47 BsAbs exhibited strong antitumor effects; specifically, IMM5605-12C10 efficiently eradicated all established tumors in all mice. A panel of BsAbs targeting CD38 and CD47 developed based on the "mAb-tarp" platform showed potent tumor-killing ability in vitro and in vivo. As BsAbs had lower affinity for binding to CD47, higher affinity for binding to CD38, no affinity for binding to RBCs, and did not induce RBC agglutination, we concluded that CD38/CD47 BsAbs are safe and have a satisfactory tolerability profile.

A phase 1/1b, first-in-human, multi-part study of DF6215, an engineered IL-2Rα-active agonist, to investigate the safety, tolerability, pharmacokinetics, and biological and clinical activity in patients with advanced solid tumors.

TPS2704 Background: IL-2 is a pleiotropic cytokine that stimulates strong anti-tumor responses by promoting expansion and activation of cytotoxic tumor-infiltrating immune cells including CD8 + T cells and NK cells (1). Aldesleukin is an approved rhIL-2; however, it has clinical limitations due to short half-life, requirement for 5 days of hospitalization per cycle, and high toxicity [eg, cytokine-related toxicity, capillary leak syndrome (CLS)] that limits its use [aldesleukin USPI]. DF6215 is a modified monovalent human IL-2 that binds to the IL2R. Preclinically, DF6215 administration results in sustained and modulated IL-2 pharmacology, leading to protracted pharmacodynamic (PD) effects and enhanced anti-tumor activity without observation of CLS in murine and primate toxicology studies. In response to the limitations of previous IL-2 therapeutics, DF6215 was designed as an IL-2Rα-active agonist with increased IL-2Rβγ stimulation to improve the benefit-to-risk ratio of historic IL-2 drugs. An additional design element is a prolonged elimination half-life due to Fc fusion, allowing for less frequent dosing. Methods: This is a first-in-human, open-label, multipart, Phase 1/1b clinical trial to characterize the initial safety, tolerability, pharmacokinetics, and preliminary efficacy of DF6215 in patients with advanced solid tumors. The Phase 1 dose escalation (DE) starting dose is 10 ug/kg IV every 2 weeks (up to 42 subjects expected to be enrolled), and the Safety/PK/PD will be explored at doses already characterized as safe in dose escalation and potentially efficacious (max of 40 subjects). Phase 1b includes an efficacy expansion (EE) cohort in subjects with advanced melanoma who have received prior anti-PD-1 agents and, if the tumor harbors a BRAF-activating mutation, a BRAF inhibitor. Key inclusion criteria include ≥ 18 years of age; ECOG PS of 0 or 1; adequate organ function, and locally advanced or metastatic solid tumors for which standard therapy options have been exhausted; and availability of baseline tumor biopsy. Primary objectives include determination of the MTD of DF6215 in DE and demonstration of clinical activity of DF6215 in the EE. Secondary objectives include assessment of safety and tolerability, pharmacokinetics, and immunogenicity of DF6215. This study plans to enroll up to 102 subjects across ~30 global centers in the US, European, and the Asia/Pacific regions, and is currently open to enrollment. 1. Arenas-Ramirez N, et al. 2015. Trends Immunol. Clinical trial information: NCT06108479 .

The promising feeder-free allogenic NK cell therapy: Clinical outcomes of GIC-102 monotherapy (GIC-102101) and synergistic potential with GI-101 (CD80-IgG4 Fc-IL2v) in advanced solid tumors and hematologic malignancies.

e14526 Background: The allogeneic Natural Killer (NK) cell therapy derived from healthy donors may overcome the short lifespan and dysfunctional anti-tumor activity of current autologous approach. This limitation often restricts treatment efficacy and necessitating high dosages and frequent infusions. GIC-102, non-engineered / feeder-free, highly potent allogeneic NK cell derived from healthy donors, is a promising alternative. Here, we present the clinical outcomes from the Phase 1 study of GIC-102, along with nonclinical evidence demonstrating outstanding pharmacokinetics (PK) and pharmacodynamics (PD) when used in combination with a novel bi-specific Fc fusion protein, GI-101 (CD80-IgG4 Fc-IL2v/NCT04977453/KEYNOTE-B59). Methods: GIC-102101, a first-in-human study, evaluated GIC-102 monotherapy at doses of 1x109 QW and 3x109 QW in patients with advanced solid tumors or hematologic malignancies. A lympho-conditioning strategy using cyclophosphamide (300 mg/m2) and fludarabine (30 mg/m2) was implemented every two cycles before GIC-102 treatment. The study employed a conventional 3+3 dose escalation scheme. The primary endpoint was to determine the safety and tolerability of GIC-102, with tumor response assessed as secondary endpoints. Additionally, the PK/PD profile of GIC-102 in combination with GI-101 was evaluated in a mouse model. Results: As of December 31, 2023, six patients have been treated with GIC-102 monotherapy including two patients with Non-Hodgkin lymphoma (NHL), and four patients with metastatic colorectal cancer (CRC). The median number of prior treatments for patients with CRC and NHL was 4 and 6, respectively. No dose limiting toxicities (DLTs) were observed and maximum tolerated dose was not reached. Treatment-related adverse events (TRAEs) occurred in 5 patients (83%), with the majority being associated with the lympho-conditioning procedure; hyponatremia, neutropenia, lymphopenia and anemia. The best overall response was complete response (CR) in 1/6 patient (NHL) and stable disease (SD) in 4/6 patients (3 CRC, 1 NHL). Treatment for 1 CR (NHL) and 2 SD (CRC) is ongoing (for NHL, 215+ days/for CRC, 160+ days and 153+ days). The in-vivo study of GIC-102 in combination with GI-101 showed significantly enhanced anti-tumor activity and in-vivo NK cell proliferation lasting up to 4 weeks. Conclusions: The GIC-102, feeder-free allogeneic NK cell, was well tolerated without DLTs and demonstrated early promise in efficacy in patients for advanced solid tumors and hematologic malignancy. Further clinical investigation of GIC-102 in combination with GI-101, bi-specific Fc fusion protein, is currently ongoing. Clinical trial information: NCT05880043 .

#1342 Updated results from the RUBY-3 study of povetacicept, an enhanced dual BAFF/APRIL antagonist, in autoantibody-associated glomerulonephritis

Abstract Background and Aims Inhibition of BAFF and/or APRIL has shown promise in IgA nephropathy (IgAN), systemic lupus erythematosus (SLE), lupus nephritis (LN), and primary membranous nephropathy (pMN), and has the potential to exert a disease-modifying effect. Povetacicept (ALPN-303) is an Fc fusion protein of a variant TACI domain engineered for more potent dual BAFF/APRIL inhibition than wild-type TACI or anti-BAFF or anti-APRIL antibodies. In a previous report, povetacicept 80 mg every 4 weeks was initially well tolerated and demonstrated promising, clinically meaningful reductions in urine protein to creatinine ratio (UPCR) and Gd-IgA1 in participants with IgAN (Tumlin J, et al. Poster TH-PO1125 presented at ASN 2023). Updated data are reported here. Method RUBY-3 is an open-label, multiple ascending dose, phase 1b/2a study of povetacicept 80 or 240 mg administered subcutaneously once every 4 weeks. Eligible participants are aged ≥18 years with biopsy-confirmed IgAN, LN, or pMN and on maximally tolerated ACE inhibitor/ARB therapy, with well-controlled blood pressure, and disease-specific immunosuppressive therapy where applicable. The primary objective is safety; secondary objectives include pharmacokinetics, pharmacodynamics, immunogenicity, biomarkers, and efficacy. Results As of 1 Dec 2023, 12 participants with IgAN have enrolled and received povetacicept 80 mg, with 7 (58%) having received ≥24 weeks of treatment. Povetacicept continues to be well tolerated, with the majority of treatment-emergent adverse events being of low grade. There have been no incidences of severe hypogammaglobulinemia (IgG &amp;lt;3 g/L) or severe infections. Povetacicept 80 mg was associated with a UPCR reduction of 52.6% at 24 weeks (n = 7). Reductions in Gd-IgA1, stable renal function, and pharmacodynamically expected decreases in immunoglobulin levels were also observed. Additional results from the 80 mg cohort with longer duration of follow-up, as well as initial results from the 240 mg dosing cohort, are planned to be presented. Conclusion Povetacicept remains well tolerated with multiple dosing and continues to demonstrate very promising activity in IgAN, strongly supporting further study in IgAN as well as other glomerulonephritis and autoantibody-associated diseases.

Development of nanoparticle vaccines utilizing designed Fc-binding homo-oligomers and RBD-Fc of SARS-CoV-2

The Fc-fused receptor binding domain (RBD-Fc) vaccine for SARS-CoV-2 has garnered significant attention for its capacity to provide effective and specific immune protection. However, its immunogenicity is limited, highlighting the need for improvement in clinical application. Nanoparticle delivery has been shown to be an effective method for enhancing antigen immunogenicity. In this study, we developed bivalent nanoparticle recombinant protein vaccines by assembling the RBD-Fc of SARS-CoV-2 and Fc-binding homo-oligomers o42.1 and i52.3 into octahedral and icosahedral nanoparticles. The formation of RBD-Fc nanoparticles was confirmed through structural characterization and cell binding experiments. Compared to RBD-Fc dimers, the nanoparticle vaccines induced more potent neutralizing antibodies (nAb) and stronger cellular immune responses. Therefore, using bivalent nanoparticle vaccines based on RBD-Fc presents a promising vaccination strategy against SARS-CoV-2 and offers a universal approach for enhancing the immunogenicity of Fc fusion protein vaccines.