Antibody biodistribution coefficients: inferring tissue concentrations of monoclonal antibodies based on the plasma concentrations in several preclinical species and human

Development of a Specifically Labeled 89Zr Antibody for the Noninvasive Imaging of Tumors Overexpressing B7-H3

B7-H3 has emerged as a promising target and potential biomarker for diagnosing tumors, evaluating treatment efficacy, and determining patient prognosis. Hu4G4 is a recombinant humanized antibody that selectively targets the extracellular domain of human B7-H3. In this study, we describe the radiolabeling of hu4G4 with the positron emission tomography (PET) emitter radionuclide zirconium 89 (89Zr) and evaluate its potency as an immuno-PET tracer for B7-H3-targeted imaging by comparing it in vitro and in vivo to [89Zr]Zr-DFO-DS-5573a using various models. The radiolabeled compound, [89Zr]Zr-desferrioxamine-hu4G4 ([89Zr]Zr-DFO-hu4G4), demonstrated a high radiochemical purity (RCP) of greater than 99% and a specific activity of 74 MBq/mg following purification. Additionally, it maintained stability in human serum albumin (HSA) and acetate buffer, preserving over 90% of its RCP after 7 days. Three cell lines targeting human B7-H3(U87/CT26-CD276/GL261-CD276) were used. Flow cytometry analysis indicated that the B7-H3-positive cells (U87/CT26-CD276/GL261-CD276) had a higher B7-H3 protein level with no expression in the B7-H3-negative cells (CT26-wt/GL261-wt) (P < 0.001). Moreover, the cellular uptake was 45.71 ± 3.78% for [89Zr]Zr-DFO-hu4G4 in CT26-CD276 cells versus only 0.93 ± 0.47% in CT26-wt cells and 30.26 ± 0.70% when [89Zr]Zr-DFO-hu4G4 in CT26-CD276 cells were blocked with 100× 8H9. The cellular uptake of [89Zr]Zr-DFO-hu4G4 was akin to that observed with [89Zr]Zr-DFO-DS-5573a with no significant differences (45.71 ± 3.78 % vs 47.07 ± 0.86 %) in CT26-CD276 cells. Similarly, the CT26-CD276 mouse model demonstrated markedly low organ uptake and elevated tumor uptake 48 h after [89Zr]Zr-DFO-hu4G4 injection. PET/CT analysis showed that the tumor-to-muscle (T/M) ratios were substantially higher compared to other imaging groups: 27.65 ± 3.17 in CT26-CD276 mice versus 11.68 ± 4.19 in CT26-wt mice (P < 0.001) and 16.40 ± 0.78 when 100× 8H9 was used to block [89Zr]Zr-DFO-hu4G4 in CT26-CD276 mice (P < 0.01) at 48 h post-injection. Additionally, the tracer showed markedly high accumulation in the tumor region (22.57 ± 3.03% ID/g), comparable to the uptake of [89Zr]Zr-DFO-DS-5573a (24.76 ± 5.36% ID/g). A dosimetry estimation study revealed that the effective dose for [89Zr]Zr-DFO-hu4G4 was 2.96 × 10-01 mSv/MBq, which falls within the acceptable range for further research in nuclear medicine. Collectively, these results indicated that [89Zr]Zr-DFO-hu4G4 was successfully fabricated and applied in B7-H3-targeted tumor PET/CT imaging, which showed excellent imaging quality and tumor detection efficacy in tumor-bearing mice. It is a promising imaging agent for identifying tumors that overexpress B7-H3 for future clinical applications.

Inter-regional pharmacokinetics and exposure-response analyses of belimumab in patients with system lupus erythematosus

AIMS

The pharmacokinetics (PK) of belimumab, a human immunoglobulin G1λ (IgG1λ) monoclonal antibody treatment for systemic lupus erythematosus (SLE), have been well reported. Clinical PK data in healthy participants and patients with SLE from Mainland China suggest lower-than-expected belimumab exposure. This study assessed inter-regional differences in belimumab exposure and efficacy via the exposure-response relationship to inform any dose-adjustment requirements.

METHODS

Data from nine interventional belimumab studies in healthy participants and patients with SLE were used to update two-compartment PK models with first-order subcutaneous (SC) absorption, and a logistic regression model characterizing the 52-week SLE Responder Index (SRI) response in adult and paediatric patients with SLE. Covariates of belimumab PK and efficacy were identified using forward selection (P > .05) and backward elimination (P < .01). The models were evaluated using statistical tests and visual predictive checks.

RESULTS

Baseline fat-free mass was the most significant covariate affecting belimumab PK; baseline albumin and IgG concentrations were also PK covariates. After adjusting for covariates, Mainland Chinese patients had significantly higher observed belimumab clearance (28%) and central volume of distribution (20%) than other populations, leading to lower-than-expected exposures. Despite this, following the same dose, they were expected to have almost identical SRI response rates vs. other populations from the exposure-response analysis.

CONCLUSIONS

Belimumab 10 mg kg-1 intravenously every 4 weeks, or 200 mg SC every week, would achieve the maximum treatment effect for North East Asian patients with SLE (including Mainland Chinese) and similar responses to patients from other regions, despite lower reported exposures in Chinese patients.

Nano- and Micro-Platforms in Therapeutic Proteins Delivery for Cancer Therapy: Materials and Strategies

Proteins have emerged as promising therapeutics in oncology due to their great specificity. Many treatment strategies are developed based on protein biologics, such as immunotherapy, starvation therapy, and pro-apoptosis therapy, while some protein biologics have entered the clinics. However, clinical translation is severely impeded by instability, short circulation time, poor transmembrane transportation, and immunogenicity. Micro- and nano-particles-based drug delivery platforms are designed to solve those problems and enhance protein therapeutic efficacy. This review first summarizes the different types of therapeutic proteins in clinical and research stages, highlighting their administration limitations. Next, various types of micro- and nano-particles are described to demonstrate how they can overcome those limitations. The potential of micro- and nano-particles are then explored to enhance the therapeutic efficacy of proteins by combinational therapies. Finally, the challenges and future directions of protein biologics carriers are discussed for optimized protein delivery.

Viral Kinetics Model of SARS-CoV-2 Infection Informs Drug Discovery, Clinical Dose, and Regimen Selection

Quantitative systems pharmacology (QSP) has been an important tool to project safety and efficacy of novel or repurposed therapies for the SARS-CoV-2 virus. Here, we present a QSP modeling framework to predict response to antiviral therapeutics with three mechanisms of action (MoA): cell entry inhibitors, anti-replicatives, and neutralizing biologics. We parameterized three distinct model structures describing virus-host interaction by fitting to published viral kinetics data of untreated COVID-19 patients. The models were used to test theoretical behaviors and map therapeutic design criteria of the different MoAs, identifying the most rapid and robust antiviral activity from neutralizing biologic and anti-replicative MoAs. We found good agreement between model predictions and clinical viral load reduction observed with anti-replicative nirmatrelvir/ritonavir (Paxlovid®) and neutralizing biologics bamlanivimab and casirivimab/imdevimab (REGEN-COV®), building confidence in the modeling framework to inform a dose selection. Finally, the model was applied to predict antiviral response with ensovibep, a novel DARPin therapeutic designed as a neutralizing biologic. We developed a new in silico measure of antiviral activity, area under the curve (AUC) of free spike protein concentration, as a metric with larger dynamic range than viral load reduction. By benchmarking to bamlanivimab predictions, we justified dose levels of 75, 225, and 600 mg ensovibep to be administered intravenously in a Phase 2 clinical investigation. Upon trial completion, we found model predictions to be in good agreement with the observed patient data. These results demonstrate the utility of this modeling framework to guide the development of novel antiviral therapeutics.

Holistic in silico developability assessment of novel classes of small proteins using publicly available sequence-based predictors

The development of novel therapeutic proteins is a lengthy and costly process, with an average attrition rate of 91% (Thomas et al. Clinical Development Success Rates and Contributing Factors 2011-2020, 2021). To increase the probability of success and ensure robust drug supply beyond approval, it is essential to assess the developability profile of new potential drug candidates as early and broadly as possible in development (Jain et al. MAbs, 2023. https://doi.org/10.1016/j.copbio.2011.06.002 ). Predicting these properties in silico is expected to be the next leap in innovation as it would enable significantly reduced development timelines combined with broader screens at lower costs. However, developing predictive algorithms typically requires substantial datasets generated under very defined conditions, a limiting factor especially for new classes of therapeutic proteins that hold immense clinical promise. Here we describe a strategy for assessing the developability of a novel class of small therapeutic Anticalin® proteins using machine learning in conjunction with a knowledge-driven approach. The knowledge-driven approach considers developability attributes such as aggregation propensity, charge variants, immunogenicity, specificity, thermal stability, hydrophobicity, and potential post-translational modifications, to calculate a holistic developability score. Based on sequence-derived descriptors as input parameters we established novel statistical models designed to predict the developability scores for Anticalin proteins. The best models yielded low root mean square errors across the entire dataset and were further validated by removing input data from individual screening campaigns and predicting developability scores for those drug candidates. The adoption of the described workflow will enable significantly streamlined preclinical development of Anticalin drug candidates and could potentially be applied to other therapeutic protein scaffolds.

Preclinical proof of principle for orally delivered Th17 antagonist miniproteins

Interleukin (IL)-23 and IL-17 are well-validated therapeutic targets in autoinflammatory diseases. Antibodies targeting IL-23 and IL-17 have shown clinical efficacy but are limited by high costs, safety risks, lack of sustained efficacy, and poor patient convenience as they require parenteral administration. Here, we present designed miniproteins inhibiting IL-23R and IL-17 with antibody-like, low picomolar affinities at a fraction of the molecular size. The minibinders potently block cell signaling in vitro and are extremely stable, enabling oral administration and low-cost manufacturing. The orally administered IL-23R minibinder shows efficacy better than a clinical anti-IL-23 antibody in mouse colitis and has a favorable pharmacokinetics (PK) and biodistribution profile in rats. This work demonstrates that orally administered de novo-designed minibinders can reach a therapeutic target past the gut epithelial barrier. With high potency, gut stability, and straightforward manufacturability, de novo-designed minibinders are a promising modality for oral biologics.

Dupilumab: Mechanism of action, clinical, and translational science

Allergic disease prevalence has increased globally with the subset of type 2 inflammatory diseases playing a substantial role. Type 2 inflammatory diseases may differ in clinical presentation, but they exhibit shared pathophysiology that is targeted by the unique pharmacology of dupilumab. Dupilumab binds to the interleukin (IL)-4 receptor alpha subunit (IL-4Rα) that blocks IL-4 and IL-13 signaling, two key drivers of type 2 inflammation. Herein, we review the mechanism of action and pharmacology of dupilumab, and the clinical evidence that led to the regulatory approvals of dupilumab for the treatment of numerous type 2 inflammatory diseases: atopic dermatitis, asthma, chronic rhinosinusitis with nasal polyposis, eosinophilic esophagitis, and prurigo nodularis.

JNJ-77242113, a highly potent, selective peptide targeting the IL-23 receptor, provides robust IL-23 pathway inhibition upon oral dosing in rats and humans

The interleukin (IL)-23 pathway is a pathogenic driver in psoriasis, psoriatic arthritis, and inflammatory bowel disease. Currently, no oral therapeutics selectively target this pathway. JNJ-77242113 is a peptide targeting the IL-23 receptor with high affinity (KD: 7.1 pM). In human cells, JNJ-77242113 potently and selectively inhibited proximal IL-23 signaling (IC50: 5.6 pM) without impacting IL-12 signaling. JNJ-77242113 inhibited IL-23-induced interferon (IFN)γ production in NK cells, and in blood from healthy donors and psoriasis patients (IC50: 18.4, 11 and 9 pM, respectively). In a rat trinitrobenzene sulfonic acid-induced colitis model, oral JNJ-77242113 attenuated disease parameters at doses ≥ 0.3 mg/kg/day. Pharmacologic activity beyond the gastrointestinal tract was also demonstrated. In blood from rats receiving oral JNJ-77242113, dose-dependent inhibition of ex vivo IL-23-stimulated IL-17A production was observed. In an IL-23-induced rat skin inflammation model, JNJ-77242113 inhibited IL-23-induced skin thickening and IL-17A, -17F and -22 gene induction. Oral dosing of JNJ-77242113 in healthy human volunteers inhibited ex vivo IL-23-stimulated IFNγ production in whole blood. Thus, JNJ-77242113 provided selective, systemic IL-23 pathway inhibition in preclinical models which translated to pharmacodynamic activity in healthy human volunteers, supporting the potential for JNJ-77242113 as a selective oral therapy for IL-23-driven immune-mediated diseases.

Neutral or Detrimental Effects of TREM2 Agonist Antibodies in Preclinical Models of Alzheimer's Disease and Multiple Sclerosis

Human genetics and preclinical studies have identified key contributions of TREM2 to several neurodegenerative conditions, inspiring efforts to modulate TREM2 therapeutically. Here, we characterize the activities of three TREM2 agonist antibodies in multiple mixed-sex mouse models of Alzheimer's disease (AD) pathology and remyelination. Receptor activation and downstream signaling are explored in vitro, and active dose ranges are determined in vivo based on pharmacodynamic responses from microglia. For mice bearing amyloid-β (Aβ) pathology (PS2APP) or combined Aβ and tau pathology (TauPS2APP), chronic TREM2 agonist antibody treatment had limited impact on microglia engagement with pathology, overall pathology burden, or downstream neuronal damage. For mice with demyelinating injuries triggered acutely with lysolecithin, TREM2 agonist antibodies unexpectedly disrupted injury resolution. Likewise, TREM2 agonist antibodies limited myelin recovery for mice experiencing chronic demyelination from cuprizone. We highlight the contributions of dose timing and frequency across models. These results introduce important considerations for future TREM2-targeting approaches.

Nonclinical and clinical characterization of MAU868, a novel human-derived monoclonal neutralizing antibody targeting BK polyomavirus VP1

Reactivation of BK polyomavirus (BKPyV) can cause significant kidney and bladder disease in immunocompromised patients. There are currently no effective, BKPyV-specific therapies. MAU868 is a novel, human immunoglobulin (Ig) G1 monoclonal antibody that binds the major capsid protein, VP1, of BKPyV with picomolar affinity, neutralizes infection by the 4 major BKPyV genotypes (EC50 ranging from 0.009-0.093 μg/mL; EC90 ranging from 0.102-4.160 μg/mL), and has comparable activity against variants with highly prevalent VP1 polymorphisms. No resistance-associated variants were identified in long-term selection studies, indicating a high in vitro barrier-to-resistance. The high-resolution crystal structure of MAU868 in complex with VP1 pentamer identified 3 key contact residues in VP1 (Y169, R170, and K172). A first-in-human study was conducted to assess the safety, tolerability, and pharmacokinetics of MAU868 following intravenous and subcutaneous administration to healthy adults in a randomized, placebo-controlled, double-blinded, single ascending dose design. MAU868 was safe and well-tolerated. All adverse events were grade 1 and resolved. The pharmacokinetics of MAU868 was typical of a human IgG, with dose-proportional systemic exposure and an elimination half-life ranging between 23 and 30 days. These results demonstrate the potential of MAU868 as a first-in-class therapeutic agent for the treatment or prevention of BKPyV disease.

Nasal tau immunotherapy clears intracellular tau pathology and improves cognitive functions in aged tauopathy mice

Pathological tau aggregates cause cognitive decline in neurodegenerative tauopathies, including Alzheimer's disease (AD). These aggregates are prevalent within intracellular compartments. Current tau immunotherapies have shown limited efficacy in clearing intracellular tau aggregates and improving cognition in clinical trials. In this study, we developed toxic tau conformation-specific monoclonal antibody-2 (TTCM2), which selectively recognized pathological tau aggregates in brain tissues from patients with AD, dementia with Lewy bodies (DLB), and progressive supranuclear palsy (PSP). TTCM2 potently inhibited tau-seeding activity, an essential mechanism underlying tauopathy progression. To effectively target intracellular tau aggregates and ensure rapid delivery to the brain, TTCM2 was loaded in micelles (TTCM2-ms) and administered through the intranasal route. We found that intranasally administered TTCM2-ms efficiently entered the brain in hTau-tauopathy mice, targeting pathological tau in intracellular compartments. Moreover, a single intranasal dose of TTCM2-ms effectively cleared pathological tau, elevated synaptic proteins, and improved cognitive functions in aged tauopathy mice. Mechanistic studies revealed that TTCM2-ms cleared intracellular, synaptic, and seed-competent tau aggregates through tripartite motif-containing 21 (TRIM21), an intracellular antibody receptor and E3 ubiquitin ligase known to facilitate proteasomal degradation of cytosolic antibody-bound proteins. TRIM21 was found to be essential for TTCM2-ms-mediated clearance of tau pathology. Our study collectively provides evidence of the effectiveness of nasal tau immunotherapy in targeting and clearing intracellular tau pathology through TRIM21 and enhancing cognition in aged tauopathy mice. This study could be valuable in designing effective tau immunotherapies for AD and other tauopathies.

Comparison of dose selection based on target engagement versus inhibition of receptor-ligand interaction for checkpoint inhibitors

Immune checkpoint inhibitors block the interaction between a receptor on one cell and its ligand on another cell, thus preventing the transduction of an immunosuppressive signal. While inhibition of the receptor-ligand interaction is key to the pharmacological activity of these drugs, it can be technically challenging to measure these intercellular interactions directly. Instead, target engagement (or receptor occupancy) is commonly measured, but may not always be an accurate predictor of receptor-ligand inhibition, and can be misleading when used to inform clinical dose projections for this class of drugs. In this study, a mathematical model explicitly representing the intercellular receptor-ligand interaction is used to compare dose prediction based on target engagement or receptor-ligand inhibition for two checkpoint inhibitors, atezolizumab and magrolimab. For atezolizumab, there is little difference between target engagement and receptor-ligand inhibition, but for magrolimab, the model predicts that receptor-ligand inhibition is significantly less than target engagement. The key variables explaining the difference between these two drugs are the relative concentrations of the target receptors and their ligands. Drug-target affinity and receptor-ligand affinity can also have divergent effects on target engagement and inhibition. These results suggest that it is important to consider ligand-receptor inhibition in addition to target engagement and demonstrate the impact of using modeling for efficacious dose estimation.

The Basis for Weekly Insulin Therapy: Evolving Evidence With Insulin Icodec and Insulin Efsitora Alfa

Basal insulin continues to be a vital part of therapy for many people with diabetes. First attempts to prolong the duration of insulin formulations were through the development of suspensions that required homogenization prior to injection. These insulins, which required once- or twice-daily injections, introduced wide variations in insulin exposure contributing to unpredictable effects on glycemia. Advances over the last 2 decades have resulted in long-acting, soluble basal insulin analogues with prolonged and less variable pharmacokinetic exposure, improving their efficacy and safety, notably by reducing nocturnal hypoglycemia. However, adherence and persistence with once-daily basal insulin treatment remains low for many reasons including hypoglycemia concerns and treatment burden. A soluble basal insulin with a longer and flatter exposure profile could reduce pharmacodynamic variability, potentially reducing hypoglycemia, have similar efficacy to once-daily basal insulins, simplify dosing regimens, and improve treatment adherence. Insulin icodec (Novo Nordisk) and insulin efsitora alfa (basal insulin Fc [BIF], Eli Lilly and Company) are 2 such insulins designed for once-weekly administration, which have the potential to provide a further advance in basal insulin replacement. Icodec and efsitora phase 2 clinical trials, as well as data from the phase 3 icodec program indicate that once-weekly insulins provide comparable glycemic control to once-daily analogues, with a similar risk of hypoglycemia. This manuscript details the technology used in the development of once-weekly basal insulins. It highlights the clinical rationale and potential benefits of these weekly insulins while also discussing the limitations and challenges these molecules could pose in clinical practice.

Favorable impact of PD1/PD-L1 antagonists on bone remodeling: an exploratory prospective clinical study and ex vivo validation

BACKGROUND

Skeletal morbidity in patients with cancer has a major impact on the quality of life, and preserving bone health while improving outcomes is an important goal of modern antitumor treatment strategies. Despite their widespread use in early disease stages, the effects of immune checkpoint inhibitors (ICIs) on the skeleton are still poorly defined. Here, we initiated a comprehensive investigation of the impact of ICIs on bone health by longitudinal assessment of bone turnover markers in patients with cancer and by validation in a novel bioengineered 3D model of bone remodeling.

METHODS

An exploratory longitudinal study was conducted to assess serum markers of bone resorption (C-terminal telopeptide, CTX) and formation (procollagen type I N-terminal propeptide, PINP, and osteocalcin, OCN) before each ICI application (programmed cell death 1 (PD1) inhibitor or programmed death-ligand 1 (PD-L1) inhibitor) for 6 months or until disease progression in patients with advanced cancer and no evidence of bone metastases. To validate the in vivo results, we evaluated osteoclast (OC) and osteoblast (OB) differentiation on treatment with ICIs. In addition, their effect on bone remodeling was assessed by immunohistochemistry, confocal microscopy, and proteomics analysis in a dynamic 3D bone model.

RESULTS

During the first month of treatment, CTX levels decreased sharply but transiently. In contrast, we observed a delayed increase of serum levels of PINP and OCN after 4 months of therapy. In vitro, ICIs impaired the maturation of preosteoclasts by inhibiting STAT3/NFATc1 signaling but not JNK, ERK, and AKT while lacking any direct effect on osteogenesis. However, using our bioengineered 3D bone model, which enables the simultaneous differentiation of OB and OC precursor cells, we confirmed the uncoupling of the OC/OB activity on exposure to ICIs by demonstrating impaired OC maturation along with increased OB differentiation.

CONCLUSION

Our study indicates that the inhibition of the PD1/PD-L1 signaling axis interferes with bone turnover and may exert a protective effect on bone by indirectly promoting osteogenesis.

Progress in novel delivery technologies to improve efficacy of therapeutic antibodies

Monoclonal antibody-based therapeutics have achieved remarkable success in treating a wide range of human diseases. However, conventional systemic delivery methods have limitations in insufficient target tissue permeability, high costs, repeated administrations, etc. Novel technologies have been developed to address these limitations and further enhance antibody therapy. Local antibody delivery via respiratory tract, gastrointestinal tract, eye and blood-brain barrier have shown promising results in increasing local concentrations and overcoming barriers. Nucleic acid-encoded antibodies expressed from plasmid DNA, viral vectors or mRNA delivery platforms also offer advantages over recombinant proteins such as sustained expression, rapid onset, and lower costs. This review summarizes recent advances in antibody delivery methods and highlights innovative technologies that have potential to expand therapeutic applications of antibodies.

Treatment of highly virulent mammarenavirus infections-status quo and future directions

INTRODUCTION

Mammarenaviruses are negative-sense bisegmented enveloped RNA viruses that are endemic in Africa, the Americas, and Europe. Several are highly virulent, causing acute human diseases associated with high case fatality rates, and are considered to be significant with respect to public health impact or bioterrorism threat.

AREAS COVERED

This review summarizes the status quo of treatment development, starting with drugs that are in advanced stages of evaluation in early clinical trials, followed by promising candidate medical countermeasures emerging from bench analyses and investigational animal research.

EXPERT OPINION

Specific therapeutic treatments for diseases caused by mammarenaviruses remain limited to the off-label use of ribavirin and transfusion of convalescent sera. Progress in identifying novel candidate medical countermeasures against mammarenavirus infection has been slow in part because of the biosafety and biosecurity requirements. However, novel methodologies and tools have enabled increasingly efficient high-throughput molecular screens of regulatory-agency-approved small-molecule drugs and led to the identification of several compounds that could be repurposed for the treatment of infection with several mammarenaviruses. Unfortunately, most of them have not yet been evaluated in vivo. The most promising treatment under development is a monoclonal antibody cocktail that is protective against multiple lineages of the Lassa virus in nonhuman primate disease models.

A phase 1 study in healthy volunteers to investigate the safety, tolerability, and pharmacokinetics of VIR-2482: a monoclonal antibody for the prevention of severe influenza A illness

The objective of this study was to evaluate the safety, tolerability, pharmacokinetics (PK), and immunogenicity of VIR-2482 in healthy adult subjects. A phase 1, first-in-human, randomized, double-blind, placebo-controlled dose-escalation study was conducted. One hundred participants were allocated to four cohorts (60 mg, 300 mg, 1,200 mg, and 1,800 mg). In each cohort, participants were randomized in a 4:1 ratio (active:placebo) to receive either VIR-2482 or volume-matched placebo by gluteal intramuscular injection. Participants remained at the investigative site under observation for 48 h, and adverse events (AEs) were collected for 56 days. PK and immunogenicity were measured up to 52 weeks post-dose. VIR-2482 was well tolerated at all doses studied. The overall incidence of AEs was comparable between VIR-2482 (68.8%) and placebo (85.0%). Nineteen VIR-2482 (23.8%) and six placebo (30.0%) recipients had Grade 1 or 2 AEs that were considered to be related to the study intervention. There were no treatment-related serious AEs. Injection-site reactions (ISRs) were reported in six (7.5%) VIR-2482 recipients, while no such reactions were reported among the placebo recipients. All ISRs were Grade 1, and there was no relationship with the dose. Median VIR-2482 serum elimination half-life ranged from 56.7 to 70.6 days across cohorts. The serum area under the curve and Cmax were dose-proportional. Nasopharyngeal VIR-2482 concentrations were approximately 2%-5% of serum levels and were less than dose-proportional. The incidence of immunogenicity across all cohorts was 1.3%. Overall, the safety, tolerability, and pharmacokinetic profile of VIR-2482 at doses up to 1,800 mg supported its further investigation as a long-acting antibody for the prevention of influenza A illness. This study has been registered at ClinicalTrials.gov under identifier NCT04033406.

Understanding the pharmacokinetic journey of Fc-fusion protein, rhIL-7-hyFc using complementary approach of two analytical methods, accelerator mass spectrometry and ELISA

Antibody-based therapeutics (ABTs), including monoclonal/polyclonal antibodies and fragment crystallizable region (Fc)-fusion proteins, are increasingly used in disease treatment, driving the global market growth. Understanding the pharmacokinetic (PK) properties of ABTs is crucial for their clinical effectiveness. This study investigated the PK profile and tissue distribution of efineptakin alfa, a long-acting recombinant human interleukin-7 (rhIL-7-hyFc), using enzyme-linked immunosorbent assay (ELISA) and accelerator mass spectrometry (AMS). Totally, four rats were injected intramuscularly with 1 mg/kg of rhIL-7-hyFc containing 14C-rhIL-7-hyFc, which was prepared via reductive methylation. Serum total radioactivity (TRA) and serum rhIL-7-hyFc concentrations were quantified using AMS and ELISA, respectively. The TRA concentrations in organs were determined by AMS. Serum TRA peaked at 10 hours with a terminal half-life of 40 hours. The rhIL-7-hyFc exhibited a mean peak concentration at around 17 hours and a rapid elimination with a half-life of 12.3 hours. Peak concentration and area under the curve of TRA were higher than those of rhIL-7-hyFc. Tissue distribution analysis showed an elevated TRA concentrations in lymph nodes, kidneys, and spleen, indicating rhIL-7-hyFc's affinity for these organs. The study also simulated the positions of 14C labeling in rhIL-7-hyFc, identifying specific residues in the fragment of rhIL-7 portion, and provided the explanation of distinct analytes targeted by each method. Combining ELISA and AMS provided advantages by offering sensitivity and specificity for quantification as well as enabling the identification of analyte forms. The integrated use of ELISA and AMS offers valuable insights for the development and optimization of ABT.

Subcutaneous Administration of Monoclonal Antibodies: Pharmacology, Delivery, Immunogenicity, and Learnings From Applications to Clinical Development

Subcutaneous (s.c.) administration of monoclonal antibodies (mAbs) can reduce treatment burden for patients and healthcare systems compared with intravenous (i.v.) infusion through shorter administration times, made possible by convenient, patient-centric devices. A deeper understanding of clinical pharmacology principles related to efficacy and safety of s.c.-administered mAbs over the past decade has streamlined s.c. product development. This review presents learnings from key constituents of the s.c. mAb development pathway, including pharmacology, administration variables, immunogenicity, and delivery devices. Restricted mAb transportation through the hypodermis explains their incomplete absorption at a relatively slow rate (pharmacokinetic (PK)) and may impact mAb-cellular interactions and/or onset and magnitude of physiological responses (pharmacodynamic). Injection volumes, formulation, rate and site of injection, and needle attributes may affect PKs and the occurrence/severity of adverse events like injection-site reactions or pain, with important consequences for treatment adherence. A review of immunogenicity data for numerous compounds reveals that incidence of anti-drug antibodies (ADAs) is generally comparable across i.v. and s.c. routes, and complementary factors including response magnitude (ADA titer), persistence over time, and neutralizing antibody presence are needed to assess clinical impact. Finally, four case studies showcase how s.c. biologics have been clinically developed: (i) by implementation of i.v./s.c. bridging strategies to streamline PD-1/PD-L1 inhibitor development, (ii) through co-development with i.v. presentations for anti-severe acute respiratory syndrome-coronavirus 2 antibodies to support rapid deployment of both formulations, (iii) as the lead route for bispecific T cell engagers (BTCEs) to mitigate BTCE-mediated cytokine release syndrome, and (iv) for pediatric patients in the case of dupilumab.

Advances and challenges in immunoPET methodology

Immuno-positron emission tomography (immunoPET) enables imaging of specific targets that play a role in targeted therapy and immunotherapy, such as antigens on cell membranes, targets in the disease microenvironment, or immune cells. The most common immunoPET applications use a monoclonal antibody labeled with a relatively long-lived positron emitter such as 89Zr (T 1/2 = 78.4 h), but smaller antibody-based constructs labeled with various other positron emitting radionuclides are also being investigated. This molecular imaging technique can thus guide the development of new drugs and may have a pivotal role in selecting patients for a particular therapy. In early phase immunoPET trials, multiple imaging time points are used to examine the time-dependent biodistribution and to determine the optimal imaging time point, which may be several days after tracer injection due to the slow kinetics of larger molecules. Once this has been established, usually only one static scan is performed and semi-quantitative values are reported. However, total PET uptake of a tracer is the sum of specific and nonspecific uptake. In addition, uptake may be affected by other factors such as perfusion, pre-/co-administration of the unlabeled molecule, and the treatment schedule. This article reviews imaging methodologies used in immunoPET studies and is divided into two parts. The first part summarizes the vast majority of clinical immunoPET studies applying semi-quantitative methodologies. The second part focuses on a handful of studies applying pharmacokinetic models and includes preclinical and simulation studies. Finally, the potential and challenges of immunoPET quantification methodologies are discussed within the context of the recent technological advancements provided by long axial field of view PET/CT scanners.

A GIPR antagonist conjugated to GLP-1 analogues promotes weight loss with improved metabolic parameters in preclinical and phase 1 settings

Obesity is a major public health crisis. Multi-specific peptides have emerged as promising therapeutic strategies for clinical weight loss. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are endogenous incretins that regulate weight through their receptors (R). AMG 133 (maridebart cafraglutide) is a bispecific molecule engineered by conjugating a fully human monoclonal anti-human GIPR antagonist antibody to two GLP-1 analogue agonist peptides using amino acid linkers. Here, we confirm the GIPR antagonist and GLP-1R agonist activities in cell-based systems and report the ability of AMG 133 to reduce body weight and improve metabolic markers in male obese mice and cynomolgus monkeys. In a phase 1, randomized, double-blind, placebo-controlled clinical study in participants with obesity ( NCT04478708 ), AMG 133 had an acceptable safety and tolerability profile along with pronounced dose-dependent weight loss. In the multiple ascending dose cohorts, weight loss was maintained for up to 150 days after the last dose. These findings support continued clinical evaluation of AMG 133.

Whole-Body Disposition and Physiologically Based Pharmacokinetic Modeling of Adeno-Associated Viruses and the Transgene Product

To facilitate model-informed drug development (MIDD) of adeno-associated virus (AAV) therapy, here we have developed a physiologically based pharmacokinetic (PBPK) model for AAVs following preclinical investigation in mice. After 2E11 Vg/mouse dose of AAV8 and AAV9 encoding a monoclonal antibody (mAb) gene, whole-body disposition of both the vector and the transgene mAb was evaluated over 3 weeks. At steady-state, the following tissue-to-blood (T/B) concentration ratios were found for AAV8/9: ∼50 for liver; ∼10 for heart and muscle; ∼2 for brain, lung, kidney, adipose, and spleen; ≤1 for bone, skin, and pancreas. T/B values for mAb were compared with the antibody biodistribution coefficients, and five different clusters of organs were identified based on their transgene expression profile. All the biodistribution data were used to develop a novel AAV PBPK model that incorporates: (i) whole-body distribution of the vector; (ii) binding, internalization, and intracellular processing of the vector; (iii) transgene expression and secretion; and (iv) whole-body disposition of the secreted transgene product. The model was able to capture systemic and tissue PK of the vector and the transgene-produced mAb reasonably well. Pathway analysis of the PBPK model suggested that liver, muscle, and heart are the main contributors for the secreted transgene mAb. Unprecedented PK data and the novel PBPK model developed here provide the foundation for quantitative systems pharmacology (QSP) investigations of AAV-mediated gene therapies. The PBPK model can also serve as a quantitative tool for preclinical study design and preclinical-to-clinical translation of AAV-based gene therapies.

Pharmacokinetics of AAV9 Mediated Trastuzumab Expression in Rat Brain Following Systemic and Local Administration

INTRODUCTION

Recombinant adeno-associated viruses(rAAVs) are an attractive tool to ensure long-term expression monoclonal antibody(mAb) in the central nervous system(CNS). It is still unclear whether systemic injection or local CNS administration of AAV9 is more beneficial for the exposure of the expressed mAb in the brain. Hence, we compared the biodistribution and transgene expression following AAV9-Trastuzumab administration through different routes.

METHODS AND RESULT

In-house generated AAV9-Trastuzumab vectors were administered at 5E+11 Vgs/rat through intravenous(IV), intracerebroventricular(ICV), intra-cisterna magna(ICM) and intrastriatal(IST) routes. Vector and trastuzumab blood/plasma concentrations were assessed at different time points up to the terminal time point of 21 days. Different brain regions in addition to the spinal cord, cerebrospinal fluid(CSF) and interstitial fluid(ISF), were also analyzed at the terminal time point. Our results show that vector biodistribution and Trastuzumab expression in the brain could the ranked as follows: IST>ICM>ICV>IV. Rapid clearance of vector was observed after administration via the ICM and ICV routes. The ICV route produced similar expression levels across different brain regions, while the ICM route had better expression in the hindbrain and spinal cord region. The IST route had higher expression in the forebrain region compared to the hindbrain region. A sharp decline in trastuzumab plasma concentration was observed across all routes of administration due to anti-trastuzumab antibody response.

CONCLUSION

In this study we have characterized vector biodistribution and transgene mAb expression after AAV9 vector administration through different routes in rats. IST and ICM represent the best administration routes to deliver antibody genes to the brain.

Quantification of clesrovimab, an investigational, half-life extended, anti-respiratory syncytial virus protein F human monoclonal antibody in the nasal epithelial lining fluid of healthy adults

BACKGROUND

Clesrovimab (MK-1654) is an investigational, half-life extended human monoclonal antibody (mAb) against RSV F glycoprotein in clinical trials as a prophylactic agent against RSV infection for infants.

METHODS

This adult study measured clesrovimab concentrations in the serum and nasal epithelial lining fluid (ELF) to establish the partitioning of the antibody after dosing. Clesrovimab concentrations in the nasal ELF were normalized for sampling dilution using urea concentrations from ELF and serum. Furthermore, in vitro RSV neutralization of human nasal ELF following dosing was also measured to examine the activity of clesrovimab in the nasal compartment.

FINDINGS

mAbs with YTE mutations are reported in literature to partition ∼1-2 % of serum antibodies into nasal mucosa. Nasal: serum ratios of 1:69-1:30 were observed for clesrovimab in two separate adult human trials after urea normalization, translating to 1.4-3.3 % of serum concentrations. The nasal PK and estimates of peripheral volume of distribution correlated with higher extravascular distribution of clesrovimab. These higher concentration of the antibody in the nasal ELF corroborated with the nasal sample's ability to neutralize RSV ex vivo. An overall trend of decreased viral plaque AUC was also noted with increasing availability of clesrovimab in the nasal ELF from a human RSV challenge study.

INTERPRETATION

Along with its extended half-life, the higher penetration of clesrovimab into the nasal epithelial lining fluid and the associated local increase in RSV neutralization activity could offer infants better protection against RSV infection.

Systemically Administered Anti-uPAR Antibody Plasma and Lung ELF Pharmacokinetics Characterized by Minimal Lung PBPK Model

Antibody-based therapeutics have recently gained keen attention for the treatment of pulmonary indications. However, systemically administered antibody exposure in the lungs needs to be better understood and remains a topic of interest. In this study, we evaluated the exposure of two different uPAR (urokinase-type plasminogen activator receptor) targeting full-length monoclonal IgGs in plasma and lung epithelial lining fluid (ELF) of mice after IP and IV administration. Antibody AK17 exhibited linear pharmacokinetics (PK) in plasma and ELF at 3 and 30 mg/kg single IV dose. The average plasma and ELF half-lives for AK17 and AK21 ranged between ~321-411 h and ~230-345 h, respectively, indicating sustained systemic and lung exposure of antibodies. The average ELF to the plasma concentration ratio of antibodies was ~0.01 and ~0.03 with IP and IV dosing, respectively, over 2 weeks post single dose. We simultaneously characterized plasma and ELF PK of antibody in mice by developing a minimal lung PBPK model for antibody. This model reasonably captured the plasma and ELF PK data while estimating three parameters. The model accounts for the convective transport of antibody into the tissues via blood and lymph flow. FcRn-mediated transcytosis was incorporated into the model for antibody distribution across the lung epithelial barrier. This model serves as a platform to predict the pulmonary PK of systemically administered antibodies and to support optimal dose selection for desired exposure in the lungs as the site of action.

Comparison of monoclonal antibody disposition predictions using different physiologically based pharmacokinetic modelling platforms

Physiologically based pharmacokinetic (PBPK) models can be used to leverage physiological and in vitro data to predict monoclonal antibody (mAb) concentrations in serum and tissues. However, it is currently not known how consistent predictions of mAb disposition are across PBPK modelling platforms. In this work PBPK simulations of IgG, adalimumab and infliximab were compared between three platforms (Simcyp, PK-Sim, and GastroPlus). Accuracy of predicted serum and tissue concentrations was assessed using observed data collected from the literature. Physiological and mAb related input parameters were also compared and sensitivity analyses were carried out to evaluate model behavior when input values were altered. Differences in serum kinetics of IgG between platforms were minimal for a dose of 1 mg/kg, but became more noticeable at higher dosages (> 100 mg/kg) and when reference (healthy) physiological input values were altered. Predicted serum concentrations of both adalimumab and infliximab were comparable across platforms, but were noticeably higher than observed values. Tissue concentrations differed remarkably between the platforms, both for total- and interstitial fluid (ISF) concentrations. The accuracy of total tissue concentrations was within a three-fold of observed values for all tissues, except for brain tissue concentrations, which were overpredicted. Predictions of tissue ISF concentrations were less accurate and were best captured by GastroPlus. Overall, these simulations show that the different PBPK platforms generally predict similar mAb serum concentrations, but variable tissue concentrations. Caution is therefore warranted when PBPK models are used to simulate effect site tissue concentrations of mAbs without data to verify the predictions.

Sabatolimab (MBG453) model-informed drug development for dose selection in patients with myelodysplastic syndrome/acute myeloid leukemia and solid tumors

Sabatolimab is a novel immunotherapy with immuno-myeloid activity that targets T-cell immunoglobulin domain and mucin domain-3 (TIM-3) on immune cells and leukemic blasts. It is being evaluated for the treatment of myeloid malignancies in the STIMULUS clinical trial program. The objective of this analysis was to support the sabatolimab dose-regimen selection in hematologic malignancies. A population pharmacokinetic (PopPK) model was fit to patients with solid tumors and hematologic malignancies, which included acute myeloid leukemia, myelodysplastic syndrome (including intermediate-, high-, and very high-risk per Revised International Prognostic Scoring System), and chronic myelomonocytic leukemia. The PopPK model, together with a predictive model of sabatolimab distribution to the bone marrow and binding to TIM-3 was used to predict membrane-bound TIM-3 bone marrow occupancy. In addition, the total soluble TIM-3 (sTIM-3) kinetics and the pharmacokinetic (PK) exposure-response relationship in patients with hematologic malignancies were examined. At intravenous doses above 240 mg Q2w and 800 mg Q4w, we observed linear PK, a plateau in the accumulation of total sTIM-3, and a flat exposure-response relationship for both safety and efficacy. In addition, the model predicted membrane-bound TIM-3 occupancy in the bone marrow was above 95% in over 95% of patients. Therefore, these results support the selection of the 400 mg Q2w and 800 mg Q4w dosing regimens for the STIMULUS clinical trial program.

Effect of Swine Glyco-humanized Polyclonal Neutralizing Antibody on Survival and Respiratory Failure in Patients Hospitalized With Severe COVID-19: A Randomized, Placebo-Controlled Trial

Background

We evaluated the safety and efficacy of XAV-19, an antispike glyco-humanized swine polyclonal neutralizing antibody in patients hospitalized with severe coronavirus disease 2019 (COVID-19).

Methods

This phase 2b clinical trial enrolled adult patients from 34 hospitals in France. Eligible patients had a confirmed diagnosis of severe acute respiratory syndrome coronavirus 2 within 14 days of onset of symptoms that required hospitalization for low-flow oxygen therapy (<6 L/min of oxygen). Patients were randomly assigned to receive a single intravenous infusion of 2 mg/kg of XAV-19 or placebo. The primary end point was the occurrence of death or severe respiratory failure between baseline and day 15.

Results

Between January 12, 2021, and April 16, 2021, 398 patients were enrolled in the study and randomly assigned to XAV-19 or placebo. The modified intention-to-treat population comprised 388 participants who received full perfusion of XAV-19 (199 patients) or placebo (189 patients). The mean (SD) age was 59.8 (12.4) years, 249 (64.2%) individuals were men, and the median time (interquartile range) from symptom onset to enrollment was 9 (7-10) days. There was no statistically significant decrease in the cumulative incidence of death or severe respiratory failure through day 15 in the XAV-19 group vs the placebo group (53/199 [26.6%] vs 48/189 [25.4%]; adjusted risk difference, 0.6%; 95% CI, -6% to 7%; hazard ratio, 1.03; 95% CI, 0.64-1.66; P = .90). In the safety population, adverse events were reported in 75.4% of 199 patients in the XAV-19 group and in 76.3% of 190 patients in the placebo group through D29.

Conclusions

Among patients hospitalized with COVID-19 requiring low-flow oxygen therapy, treatment with a single intravenous dose of XAV-19, compared with placebo, did not show a significant difference in terms of disease progression at day 15.

Analysis of clinical failure of anti-tau and anti-synuclein antibodies in neurodegeneration using a quantitative systems pharmacology model

Misfolded proteins in Alzheimer's disease and Parkinson's disease follow a well-defined connectomics-based spatial progression. Several anti-tau and anti-alpha synuclein (aSyn) antibodies have failed to provide clinical benefit in clinical trials despite substantial target engagement in the experimentally accessible cerebrospinal fluid (CSF). The proposed mechanism of action is reducing neuronal uptake of oligomeric protein from the synaptic cleft. We built a quantitative systems pharmacology (QSP) model to quantitatively simulate intrasynaptic secretion, diffusion and antibody capture in the synaptic cleft, postsynaptic membrane binding and internalization of monomeric and oligomeric tau and aSyn proteins. Integration with a physiologically based pharmacokinetic (PBPK) model allowed us to simulate clinical trials of anti-tau antibodies gosuranemab, tilavonemab, semorinemab, and anti-aSyn antibodies cinpanemab and prasineuzumab. Maximal target engagement for monomeric tau was simulated as 45% (semorinemab) to 99% (gosuranemab) in CSF, 30% to 99% in ISF but only 1% to 3% in the synaptic cleft, leading to a reduction of less than 1% in uptake of oligomeric tau. Simulations for prasineuzumab and cinpanemab suggest target engagement of free monomeric aSyn of only 6-8% in CSF, 4-6% and 1-2% in the ISF and synaptic cleft, while maximal target engagement of aggregated aSyn was predicted to reach 99% and 80% in the synaptic cleft with similar effects on neuronal uptake. The study generates optimal values of selectivity, sensitivity and PK profiles for antibodies. The study identifies a gradient of decreasing target engagement from CSF to the synaptic cleft as a key driver of efficacy, quantitatively identifies various improvements for drug design and emphasizes the need for QSP modelling to support the development of tau and aSyn antibodies.

Radioimmunotherapy Targeting B7-H3 in situ glioma models enhanced antitumor efficacy by Reconstructing the tumor microenvironment

Radionuclide drug conjugates (RDCs) with antibodies serve as a novel approach for the treatment of malignant tumors including glioblastoma. However, RDCs require optimal antibodies to work efficiently. Hu4G4, a novel B7-H3-targeting humanized monoclonal IgG1 antibody, is highly specific for the human B7-H3 protein (a marker of tumor cells, including glioblastoma cells). Herein, we established 131I-labeled hu4G4 (131I-hu4G4) and showed that it specifically bound to B7-H3 with high affinity (Kd = 0.99 ± 0.07 nM) and inhibited the growth of U87 cells in vitro. 131I-hu4G4 displayed potent in situ antitumor activity in a mouse model of glioma based on GL261 Red-Fluc-B7-H3 cells. More importantly, 131I-hu4G4 remodeled the tumor microenvironment and promoted the transformation of glioma from "cold" to "hot" tumors by promoting CD4+ and CD8+ T cell infiltration and the polarization of M2 to M1. Therefore, the antitumor activity observed with 131I-hu4G4, together with its ability to enhance antitumor immune responses, makes it a novel candidate for radioimmunotherapy of glioblastoma.

Development of a New Method to Evaluate the Biodistribution of Antibodies Using Non-Radioactive Metal Labeling and Inductively Coupled Plasma Mass Spectrometry

PURPOSE

The use of radiolabeled compounds is associated with a number of limitations. Therefore, a new method for the radioisotope-free evaluation of antibody distribution using metal labeling and inductively coupled plasma-mass spectrometry (ICP-MS) was developed herein.

METHODS

Indium-labeled monoclonal antibodies were administrated intravenously to tumor-bearing mice and cynomolgus monkeys, and antibody concentrations in plasma and tissues were measured by ICP-MS. The results were compared with those obtained using a ligand binding assay (LBA) and radioisotope-labeled antibody administration. Indium-, terbium-, holmium-, and yttrium-labeled cetuximab were co-administered to one C57BL/6 J mouse for simultaneous PK and tissue distribution evaluations.

RESULTS

The administration of a radioactive or non-radioactive indium-labeled anti-human interleukin-6 receptor (hIL-6R) antibody to tumor-bearing hIL-6R transgenic mice resulted in similar plasma antibody concentration-time profiles by ICP-MS, a ligand binding assay (LBA), and gamma-ray detector. Liver, kidney, brain, spleen, and tumor concentrations of antibodies measured by ICP-MS were similar to those after the administration of radiolabeled anti-hIL-6R antibodies. Following the administration of indium-labeled cetuximab to cynomolgus monkeys, plasma antibody concentrations measured by ICP-MS were similar to those measured by LBA, and antibody concentrations in organs were evaluable by ICP-MS. The PK of all metals were similar to antibody PK evaluated by LBA, and concentrations in each tissue were equivalent among metals.

CONCLUSIONS

The assessment of antibody distribution using ICP-MS is a novel alternative to the traditional radiolabeled approach. It facilitates the assessment of antibody distribution in the early stages of drug discovery and accelerates the assessment of target engagement.

Safety and tolerability study of sotrovimab (VIR-7831) prophylaxis against COVID-19 infection in immunocompromised individuals with impaired SARS-CoV-2 humoral immunity

BACKGROUND

Multiple vaccines have been approved since August 2021 to prevent infection with SARS-CoV-2; however, 20-40% of immunocompromised people fail to develop SARS-CoV-2 spike antibodies after COVID-19 vaccination and remain at high risk of infection and more severe illness than non-immunocompromised hosts. Sotrovimab (VIR-7831) is a monoclonal neutralizing antibody that binds a conserved epitope on the SARS-CoV-2 spike protein. It is neither renally excreted nor metabolized by P450 enzymes and therefore unlikely to interact with concomitant medications (e.g., immunosuppressive medications). In this open-label feasibility study protocol, we will define the optimal dose and dosing interval of sotrovimab as pre-exposure prophylaxis for immunocompromised individuals as well as its safety and tolerability in this population specifically.

METHODS

We will enroll 93 eligible immunocompromised adults with a negative or low-positive (< 50 U/mL) SARS-CoV-2 spike antibody. In phase 1, the first 10 patients will participate in a lead-in pharmacokinetics (PK) cohort study to determine the optimal dosing interval. Phase 2 will expand this population to 50 participants to examine rates of infusion-related reactions (IRR) with a 30-min 500 mg sotrovimab IV infusion. Phase 3 will be an expansion cohort for further assessment of the safety and tolerability of sotrovimab. In phase 4, the first 10 patients receiving 2000 mg IV of sotrovimab on the second sotrovimab infusion day will comprise a lead-in safety cohort that will inform the duration of observation following administration of the drug. The patients will be followed for safety and COVID-19 events for 36 weeks after the second dose.

DISCUSSION

In a previous phase III randomized, placebo-controlled pivotal trial, there were no significant differences in the prevalence of adverse events in patients receiving sotrovimab vs. placebo. Thus, we propose an open-label feasibility study protocol of sotrovimab as pre-exposure prophylaxis for immunocompromised individuals to evaluate its PK in immunocompromised individuals with impaired SARS-CoV-2 humoral immunity and define optimal dosing intervals. We also aim to determine COVID-19 infections over the study period and self-reported quality of life measures throughout the study.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05210101.

Assessment of Epithelial Lining Fluid Partitioning of Systemically Administered Monoclonal Antibodies in Rats

For systemically administered monoclonal antibodies (mAbs) with pharmacological targets in the epithelial lining fluid (ELF), information on the partitioning of mAb between plasma and ELF is instrumental for dose predictions. Bronchoalveolar lavage (BAL) combined with measurements of urea as indicator of sample dilution is often used to estimate ELF concentrations of a drug. However, unbalanced extraction of mAb and urea could potentially lead to a systematic bias in the back-calculated ELF concentration. In the present study 0.5, 1, or 4 mL phosphate-buffered saline was instilled to lungs of rats to obtain lavage samples after systemic dosing of mAb and tool small molecule (n≥4/group). Furthermore, extraction of urea, mAb and the small molecule was assessed by repeatedly lavaging the lung (n = 4). There was no statistically significant difference in the calculated partitioning into ELF between the evaluated instillation volumes. Repeated BAL demonstrated that urea and the small molecule were extracted from other sources than the ELF. In contrast, there was limited to none in-flow of mAb into the lavage fluid. The unbalanced extraction of urea and mAb could theoretically result in underestimated ELF concentrations and the calculated partitioning of 0.17±0.062 might therefore constitute a lower boundary for the true partitioning.

Passive immunization inhibits tau phosphorylation and improves recognition learning and memory in 3xTg-AD mice

Tau pathology is essential in the pathogenesis of Alzheimer's disease (AD) and related tauopathies. Tau immunotherapy aimed at reducing the progression of tau pathology provides a potential therapeutic strategy for treating these diseases. By screening monoclonal antibodies 43D, 63B, 39E10, and 77G7 that recognize epitopes ranging from tau's N-terminus to C-terminus, we found the 77G7, which targets the microtubule-binding domain promoted tau clearance in a dose-dependent manner by entering neuronal cells in vitro. Intra-cerebroventricular injection of 77G7 antibody reduced tau levels in the wild-type FVB mouse brain. Without influencing the levels of detergent-insoluble and aggregated tau, intravenous injection of 77G7 reduced tau hyperphosphorylation in the brain and improved novel object recognition but not spatial learning and memory in 15-18-month-old 3xTg-AD mice. These studies suggest that epitopes recognized by tau antibodies are crucial for the efficacy of immunotherapy. Immunization with antibody 77G7 provides a novel potential opportunity for tau-directed immunotherapy of AD and related tauopathies.

Laboratory safety evaluation of lokivetmab, a canine anti-interleukin-31 monoclonal antibody, in dogs

Lokivetmab (Cytopoint®, Zoetis) is a canine monoclonal antibody that specifically binds and neutralizes interleukin (IL)-31. Lokivetmab is approved for use in dogs for the treatment of atopic dermatitis (AD) and allergic dermatitis. The laboratory safety of lokivetmab was evaluated in 2 studies by adapting the science-based, case-by-case approach used for preclinical and early clinical safety evaluation of human biopharmaceuticals. The main objectives were to demonstrate the safety of lokivetmab in healthy laboratory Beagle dogs by using integrated clinical, morphologic, and functional evaluations. In Study 1, dogs were treated s.c. with saline or lokivetmab at 3.3 mg/kg (1X, label dose) or 10 mg/kg (3X intended dose) for 7 consecutive monthly doses, with terminal pathology and histology assessments. In Study 2, the functional immune response was demonstrated in naïve dogs using the T-cell dependent antibody response (TDAR) test with 2 different dose levels of unadjuvanted keyhole limpet hemocyanin (KLH) as the model immunogen. The primary endpoint was anti-KLH IgG antibody titer, and secondary endpoints were ex vivo IL-2 enzyme-linked immunospot (ELISpot) and peripheral blood mononuclear cell lymphoproliferation assays. Both studies included monitoring general health, periodic veterinary clinical evaluations, serial clinical pathology and toxicokinetics, and monitoring for anti-drug antibodies. In both studies, the health of dogs receiving lokivetmab was similar to controls, with no treatment-related changes uncovered. Extensive pathology evaluations of immune tissues (Study 1) revealed no lokivetmab-related morphologic changes, and in dogs treated at 10 mg/kg lokivetmab, immunization with the model antigen KLH did not impair the functional antibody or T-cell recall responses. There were no immunogenicity-related or hypersensitivity-related responses observed in either study. These studies in healthy laboratory dogs showed that lokivetmab was well-tolerated, did not produce any treatment-related effects, and had no effect on immune system morphology or its functional response. These studies also demonstrated the utility of a science-based case-by-case approach to the safety evaluation of a veterinary biopharmaceutical product.

Anti-α-synuclein c-terminal antibodies block PFF uptake and accumulation of phospho-synuclein in preclinical models of Parkinson's disease

Parkinson's disease (PD), a neurodegenerative disease affecting dopaminergic (DA) neurons, is characterized by decline of motor function and cognition. Dopaminergic cell loss is associated with accumulation of toxic alpha synuclein aggregates. As DA neuron death occurs late in the disease, therapeutics that block the spread of alpha synuclein may offer functional benefit and delay disease progression. To test this hypothesis, we generated antibodies to the C terminal region of synuclein with high nanomolar affinity and characterized them in in vitro and in vivo models of spread. Interestingly, we found that only antibodies with high affinity to the distal most portion of the C-terminus robustly reduced uptake of alpha synuclein preformed fibrils (PFF) and accumulation of phospho (S129) alpha synuclein in cell culture. Additionally, the antibody treatment blocked the spread of phospho (S129) alpha synuclein associated-pathology in a mouse model of synucleinopathy. Blockade of neuronal PFF uptake by different antibodies was more predictive of in vivo activity than their binding potency to monomeric or oligomeric forms of alpha synuclein. These data demonstrate that antibodies directed to the C-terminus of the alpha synuclein have differential effects on target engagement and efficacy. Furthermore, our data provides additional support for the development of alpha synuclein antibodies as a therapeutic strategy for PD patients.

Phase 1 study of safety, pharmacokinetics, and antiviral activity of SARS-CoV-2 neutralizing monoclonal antibody ABBV-47D11 in patients with COVID-19

ABBV-47D11 is a neutralizing monoclonal antibody that targets a mutationally conserved hydrophobic pocket distal to the ACE2 binding site of SARS-CoV-2. This first-in-human safety, pharmacokinetics, and antiviral pharmacodynamic assessment in patients with COVID-19 provide an initial evaluation of this antibody that may allow further development. This multicenter, randomized, double-blind, and placebo-controlled single ascending dose study of ABBV-47D11 (180, 600, or 2400 mg) as an intravenous infusion, was in hospitalized and non-hospitalized (confined) adults with mild to moderate COVID-19. Primary outcomes were grade 3 or higher study drug-related adverse events and infusion-related reactions. Secondary outcomes were pharmacokinetic parameters and concentration-time profiles to Day 29, immunogenicity (anti-drug antibodies), and antiviral activity (change in RT-PCR viral load) from baseline to Days 15 and 29. ABBV-47D11 single doses up to 2400 mg were safe and tolerated and no safety signals were identified. The pharmacokinetics of ABBV-47D11 were linear and showed dose-proportional increases in serum concentrations with ascending doses. The exploratory anti-SARS-CoV-2 activity revealed a reduction of viral load at and above the 600 mg dose of ABBV-47D11 regardless of patient demographics and baseline characteristics, however; because of the high inter-individual variability and small sample size a statistical significance was not reached. There is potential for anti-SARS-CoV-2 activity with ABBV-47D11 doses of 600 mg or higher, which could be evaluated in future clinical trials designed and powered to assess viral load reductions and clinical benefit.

Pharmacokinetic and Pharmacodynamic Effects of Polyclonal Antibodies against SARS-CoV2 in Mice

Despite ongoing vaccination efforts to prevent SARS-CoV-2 infections, treatment tools are still necessary to address the ongoing COVID-19 pandemic. We report here that COVID-HIGIV, a human immunoglobulin product for treatment of COVID-19, provided a significant survival benefit in SARS-CoV-2 infected transgenic mice compared to controls. COVID-HIGIV also has similar pharmacokinetic profiles in healthy and SARS-CoV-2 infected mice over time after intravenous administration, with identical or comparable Tmax, Cmax, AUC0-∞ and Cl. AUC0-last increased and mean residence time, T1/2, and Vd reduced in infected animals compared to healthy animals. These data suggest that COVID-HIGIV may be an effective treatment for SARS-CoV-2 infection when given early after exposure.

A Non-radiometric Approach to Determine Tissue Vascular Blood Volume in Biodistribution Studies

The aim of this research was to develop a reliable non-radiometric method to measure the residual blood in tissue without the need for perfusion or radiometric measurements in biodistribution studies. It was found that the perfusion method not only was ineffective in removing blood from tissue, but also introduced additional variability in the determination of tissue drug exposure and was not reproducible across studies. In addition, the use of hemoglobin as an endogenous protein and biomarker for tissue blood content was studied and it was found that hemoglobin measurement in tissue was not a reliable and effective approach for determination of residual blood level in tissue. To evaluate an alternative method for addressing the tissue blood level in biodistribution studies, animals were dosed with a Residual Blood Determinant Reagent (RBDR) 5 min prior to tissue harvesting. The level of RBDR, an exogenous protein, was measured in whole blood homogenate and in tissue lysate. Based on the level of the RBDR, the vascular blood volume (VBV) in tissue was calculated and then the tissue exposures were corrected based on the blood volumes. The tissue VBVs measured by the RBDR method were comparable with the literature values obtained by radiometric measurements.

A multi-model approach to predict efficacious clinical dose for an anti-TGF-β antibody (GC2008) in the treatment of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heterogeneous group of inherited bone dysplasias characterized by reduced skeletal mass and bone fragility. Although the primary manifestation of the disease involves the skeleton, OI is a generalized connective tissue disorder that requires a multidisciplinary treatment approach. Recent studies indicate that application of a transforming growth factor beta (TGF-β) neutralizing antibody increased bone volume fraction (BVF) and strength in an OI mouse model and improved bone mineral density (BMD) in a small cohort of patients with OI. In this work, we have developed a multitiered quantitative pharmacology approach to predict human efficacious dose of a new anti-TGF-β antibody drug candidate (GC2008). This method aims to translate GC2008 pharmacokinetic/pharmacodynamic (PK/PD) relationship in patients, using a number of appropriate mathematical models and available preclinical and clinical data. Compartmental PK linked with an indirect PD effect model was used to characterize both pre-clinical and clinical PK/PD data and predict a GC2008 dose that would significantly increase BMD or BVF in patients with OI. Furthermore, a physiologically-based pharmacokinetic model incorporating GC2008 and the body's physiological properties was developed and used to predict a GC2008 dose that would decrease the TGF-β level in bone to that of healthy individuals. By using multiple models, we aim to reveal information for different aspects of OI disease that will ultimately lead to a more informed dose projection of GC2008 in humans. The different modeling efforts predicted a similar range of pharmacologically relevant doses in patients with OI providing an informed approach for an early clinical dose setting.

Treatment of Sindbis Virus-Infected Neurons with Antibody to E2 Alters Synthesis of Complete and nsP1-Expressing Defective Viral RNAs

Alphaviruses are positive-sense RNA viruses that are important causes of viral encephalomyelitis. Sindbis virus (SINV), the prototype alphavirus, preferentially infects neurons in mice and is a model system for studying mechanisms of viral clearance from the nervous system. Antibody specific to the SINV E2 glycoprotein plays an important role in SINV clearance, and this effect is reproduced in cultures of infected mature neurons. To determine how anti-E2 antibody affects SINV RNA synthesis, Oxford Nanopore Technologies direct long-read RNA sequencing was used to sequence viral RNAs following antibody treatment of infected neurons. Differentiated AP-7 rat olfactory neuronal cells, an in vitro model for mature neurons, were infected with SINV and treated with anti-E2 antibody. Whole-cell RNA lysates were collected for sequencing of poly(A)-selected RNA 24, 48, and 72 h after infection. Three primary species of viral RNA were produced: genomic, subgenomic, and defective viral genomes (DVGs) encoding the RNA capping protein nsP1. Antibody treatment resulted in overall lower production of SINV RNA, decreased synthesis of subgenomic RNA relative to genomic RNA, and suppressed production of the nsP1 DVG. The nsP1 DVG was packaged into virus particles and could be translated. Because antibody-treated cells released a higher proportion of virions with noncapped genomes and transient transfection to express the nsP1 DVG improved viral RNA capping in antibody-treated cells, we postulate that one mechanism by which antibody inhibits SINV replication in neurons is to suppress DVG synthesis and thus decrease production of infectious virions containing capped genomes. IMPORTANCE Alphaviruses are important causes of viral encephalomyelitis without approved treatments or vaccines. Antibody to the Sindbis virus (SINV) E2 glycoprotein is required for immune-mediated noncytolytic virus clearance from neurons. We used direct RNA nanopore sequencing to evaluate how anti-E2 antibody affects SINV replication at the RNA level. Antibody altered the viral RNAs produced by decreasing the proportion of subgenomic relative to genomic RNA and suppressing production of a previously unrecognized defective viral genome (DVG) encoding nsP1, the viral RNA capping enzyme. Antibody-treated neurons released a lower proportion of SINV particles with capped genomes necessary for translation and infection. Decreased nsP1 DVG production in antibody-treated neurons led to lower expression of nsP1 protein, decreased genome capping efficiency, and release of fewer infectious virus particles. Capping was increased with exogenous expression of the nsP1 DVG. These studies identify a novel alphavirus DVG function and new mechanism for antibody-mediated control of virus replication.

Translational pharmacokinetics of a novel bispecific antibody against Ebola virus (MBS77E) from animal to human by PBPK modeling & simulation

The goal of this study was to construct a PBPK model to accelerate the translation of MBS77E, a humanized bispecific antibody against the Ebola virus. In-depth nonclinical pharmacokinetic studies in rats, monkeys, wild-type mice and transgenic mice were conducted. The pH-dependent affinities (K_D) of MBS77E to recombinant FcRn of different species were determined by surface plasmon resonance analysis. A mechanistic whole-body PBPK model of MBS77E was developed and validated in the assessment of PK profiles and tissue distributions in preclinical models. This PBPK model was finally used to predict human PK behaviors of MBS77E. Simulations from the PBPK model with measured and fitted parameters were able to yield good predictions of the serum and tissue pharmacokinetic parameters of MBS77E within 2-fold errors. The predicted serum concentration in humans was able to maintain a sufficiently high level for more than 14 days after 50 mg/kg i.v. administrating. This achievement unlocks that PBPK modeling is a powerful tool to gain insights into the properties of antibody drugs. It guided experimental efforts to obtain necessary information before entry into humans.

Efficacy of COVID-HIGIV in animal models of SARS-CoV-2 infection

In late 2019 the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus emerged in China and quickly spread into a worldwide pandemic. It has caused millions of hospitalizations and deaths, despite the use of COVID-19 vaccines. Convalescent plasma and monoclonal antibodies emerged as major therapeutic options for treatment of COVID-19. We have developed an anti-SARS-CoV-2 immunoglobulin intravenous (Human) (COVID-HIGIV), a potential improvement from using convalescent plasma. In this report the efficacy of COVID-HIGIV was evaluated in hamster and mouse models of SARS-CoV-2 infection. COVID-HIGIV treatment in both mice and hamsters significantly reduced the viral load in the lungs. Among COVID-HIGIV treated animals, infection-related body weight loss was reduced and the animals regained their baseline body weight faster than the PBS controls. In hamsters, COVID-HIGIV treatment reduced infection-associated lung pathology including lung inflammation, and pneumocyte hypertrophy in the lungs. These results support ongoing trials for outpatient treatment with COVID-HIGIV for safety and efficacy evaluation (NCT04910269, NCT04546581).

Tau antibody 77G7 targeting microtubule binding domain suppresses proteopathic tau to seed tau aggregation

INTRODUCTION

Neurofibrillary tangle (NFT) of hyperphosphorylated tau is a hallmark of Alzheimer's disease (AD) and related tauopathies. Tau lesion starts in the trans-entorhinal cortex, from where it spreads to limbic regions, followed by neocortical areas. The regional distribution of NFTs associates with the progression of AD. Accumulating evidence suggests that proteopathic tau can seed tau aggregation in a prion-like fashion in vitro and in vivo. Inhibition of tau seeding activity could provide a potential therapeutic opportunity to block the propagation of tau pathology in AD and related tauopathies.

AIMS

In the present study, we investigated the role of 77G7, a monoclonal tau antibody to the microtubule-binding repeats, in repressing the seeding activity of proteopathic tau.

RESULTS

We found that 77G7 had a higher affinity toward aggregated pathological tau fractions than un-aggregated tau derived from AD brain. 77G7 inhibited the internalization of tau aggregates by cells, blocked AD O-tau to capture normal tau, and to seed tau aggregation in vitro and in cultured cells. Tau pathology induced by hippocampal injection of AD O-tau in 3xTg-AD mice was suppressed by mixing 77G7 with AD O-tau. Intravenous administration of 77G7 ameliorated site-specific hyperphosphorylation of tau induced by AD O-tau in the hippocampi of Tg/hTau mice.

CONCLUSION

These findings indicate that 77G7 can effectively suppress the seeding activity of AD O-tau and thus could be developed as a potential immunotherapeutic drug to inhibit the propagation of tau pathology in AD and related tauopathies.

Optimal imaging time points considering accuracy and precision of Patlak linearization for 89Zr-immuno-PET: a simulation study

Purpose

Zirconium-89-immuno-positron emission tomography (⁸⁹Zr-immuno-PET) has enabled visualization of zirconium-89 labelled monoclonal antibody (⁸⁹Zr-mAb) uptake in organs and tumors in vivo. Patlak linearization of ⁸⁹Zr-immuno-PET quantification data allows for separation of reversible and irreversible uptake, by combining multiple blood samples and PET images at different days. As one can obtain only a limited number of blood samples and scans per patient, choosing the optimal time points is important. Tissue activity concentration curves were simulated to evaluate the effect of imaging time points on Patlak results, considering different time points, input functions, noise levels and levels of reversible and irreversible uptake.

Methods

Based on ⁸⁹Zr-mAb input functions and reference values for reversible (V_T) and irreversible (K_i) uptake from literature, multiple tissue activity curves were simulated. Three different ⁸⁹Zr-mAb input functions, five time points between 24 and 192 h p.i., noise levels of 5, 10 and 15%, and three reference K_i and V_T values were considered. Simulated K_i and V_T were calculated (Patlak linearization) for a thousand repetitions. Accuracy and precision of Patlak linearization were evaluated by comparing simulated K_i and V_T with reference values.

Results

Simulations showed that K_i is always underestimated. Inclusion of time point 24 h p.i. reduced bias and variability in V_T, and slightly reduced bias and variability in K_i, as compared to combinations of three later time points. After inclusion of 24 h p.i., minimal differences were found in bias and variability between different combinations of later imaging time points, despite different input functions, noise levels and reference values.

Conclusion

Inclusion of a blood sample and PET scan at 24 h p.i. improves accuracy and precision of Patlak results for ⁸⁹Zr-immuno-PET; the exact timing of the two later time points is not critical.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00927-6.

Bispecific antibody-derived molecules to target persistent HIV infection

HIV infection persists despite durable and potent antiviral therapy. To target persistent HIV infection, one major strategy aims to induce HIV provirus expression using latency reversing agents and then eliminate these reservoir cells via immune responses enhanced by treatment with antibody-derived bispecific molecules. The specificities of anti-HIV-1 envelope monoclonal antibodies have been incorporated into bispecific molecules that can recognize infected cells and recruit cytotoxic immune cells to eliminate them. This concept seeks to engineer a unique and potent effector response based on the opportunity to target conserved viral epitopes on infected cells, and recruit broad populations of immune effector cells that are not limited by major histocompatibility complex restrictions or other programmed specificity constraints. This article provides a review of bispecific DART® molecules and other dual-specificity antibody-based molecules that function by co-engaging CD3-expressing T cells or CD16A-expressing NK cells with HIV-1-infected cells.

An anti-CTLA-4 heavy chain-only antibody with enhanced Treg depletion shows excellent preclinical efficacy and safety profile

The value of anti-CTLA-4 antibodies in cancer therapy is well established. However, the broad application of currently available anti-CTLA-4 therapeutic antibodies is hampered by their narrow therapeutic index. It is therefore challenging and attractive to develop the next generation of anti-CTLA-4 therapeutics with improved safety and efficacy. To this end, we generated fully human heavy chain-only antibodies (HCAbs) against CTLA-4. The hIgG1 Fc domain of the top candidate, HCAb 4003-1, was further engineered to enhance its regulatory T (T_reg) cell depletion effect and to decrease its half-life, resulting in HCAb 4003-2. We tested these HCAbs in in vitro and in vivo experiments in comparison with ipilimumab and other anti-CTLA4 antibodies. The results show that human HCAb 4003-2 binds human CTLA-4 with high affinity and potently blocks the binding of B7-1 (CD80) and B7-2 (CD86) to CTLA-4. The results also show efficient tumor penetration. HCAb 4003-2 exhibits enhanced antibody-dependent cellular cytotoxicity function, lower serum exposure, and more potent anti-tumor activity than ipilimumab in murine tumor models, which is partly driven by a substantial depletion of intratumoral T_regs. Importantly, the enhanced efficacy combined with the shorter serum half-life and less systemic drug exposure in vivo potentially provides an improved therapeutic window in cynomolgus monkeys and preliminary clinical applications. With its augmented efficacy via T_reg depletion and improved safety profile, HCAb 4003-2 is a promising candidate for the development of next generation anti-CTLA-4 therapy.

Designing antibodies as therapeutics

Antibody therapeutics are a large and rapidly expanding drug class providing major health benefits. We provide a snapshot of current antibody therapeutics including their formats, common targets, therapeutic areas, and routes of administration. Our focus is on selected emerging directions in antibody design where progress may provide a broad benefit. These topics include enhancing antibodies for cancer, antibody delivery to organs such as the brain, gastrointestinal tract, and lungs, plus antibody developability challenges including immunogenicity risk assessment and mitigation and subcutaneous delivery. Machine learning has the potential, albeit as yet largely unrealized, for a transformative future impact on antibody discovery and engineering.

Optimisation of anti-interleukin-6 therapy: Precision medicine through mathematical modelling

Background

Dysregulated interleukin (IL)-6 production can be characterised by the levels present, the kinetics of its rise and its inappropriate location. Rapid, excessive IL-6 production can exacerbate tissue damage in vital organs. In this situation, therapy with an anti-IL-6 or anti-IL-6 receptor (IL-6R) monoclonal antibody, if inappropriately dosed, may be insufficient to fully block IL-6 signalling and normalise the immune response.

Methods

We analysed inhibition of C-reactive protein (CRP) – a biomarker for IL-6 activity – in patients with COVID-19 or idiopathic multicentric Castleman disease (iMCD) treated with tocilizumab (anti-IL-6R) or siltuximab (anti-IL-6), respectively. We used mathematical modelling to analyse how to optimise anti-IL-6 or anti-IL-6R blockade for the high levels of IL-6 observed in these diseases.

Results

IL-6 signalling was insufficiently inhibited in patients with COVID-19 or iMCD treated with standard doses of anti-IL-6 therapy. Patients whose disease worsened throughout therapy had only partial inhibition of CRP production. Our model demonstrated that, in a scenario representative of iMCD with persistent high IL-6 production not controlled by a single dose of anti-IL-6 therapy, repeated administration more effectively inhibited IL-6 activity. In a situation with rapid, high, dysregulated IL-6 production, such as severe COVID-19 or a cytokine storm, repeated daily administration of an anti-IL-6/anti-IL-6R agent, or alternating daily doses of anti-IL-6 and anti-IL-6R therapies, could neutralise IL-6 activity.

Conclusion

In clinical practice, IL-6 inhibition should be individualised based on pathophysiology to achieve full blockade of CRP production.

Funding

EUSA Pharma funded medical writing assistance and provided access to the phase II clinical data of siltuximab for analysis.

Preclinical Characterization of LY3209590, a Novel Weekly Basal Insulin Fc-fusion Protein

The benefit of once-weekly basal insulin is less frequent dosing, which has the potential to reduce the barrier to injection therapy and impact patient activation, adherence/compliance, quality of life, and outcomes. Basal Insulin Fc (BIF, LY3209590, or insulin efsitora alfa) is a once-weekly basal insulin in clinical testing for type 1 and type 2 diabetes mellitus. BIF is comprised of a novel single-chain variant of insulin fused to a human IgG2 Fc domain using a peptide linker. The in vitro binding affinity of BIF for the human insulin receptor (IR) was two orders of magnitude weaker relative to human insulin. BIF stimulated IR phosphorylation in cells with reduced potency, yet full agonism, and exhibited a significantly faster dephosphorylation kinetic profile than human insulin or AspB10 insulin. BIF stimulated de novo lipogenesis in 3T3-L1 adipocytes and cell proliferation in SAOS-2 and H4IIE cells with {greater than or equal to}70-fold reduction in in vitro potency compared to human insulin. BIF possessed markedly reduced binding to hIGF-1R making definitive measurements unattainable. In vivo pharmacology studies using streptozotocin-treated diabetic rats demonstrated a significant decrease in blood glucose compared to vehicle-treated animals 24h post-injection, persisting through 336h following subcutaneous administration. In streptozotocin-treated rats, BIF reached T_max at 48h and possessed a clearance rate of ~0.85 mL/hr/kg, with a t_1/2 of ~120h following subcutaneous administration. These results demonstrate BIF has an in vitro pharmacological profile similar to native insulin, with significantly reduced potency and an extended time-action profile in vivo that supports QW dosing in humans. Significance Statement BIF is a novel basal insulin Fc-fusion protein designed for once-weekly dosing. In this study we demonstrate that BIF has an in vitro pharmacological profile similar to human insulin, but with weaker potency across assays for IR binding and activity. BIF has a PD and PK profile in STZ-treated rats supportive of weekly dosing in humans.