Antibody pharmacokinetics and pharmacodynamics

Emerging trends and therapeutic applications of monoclonal antibodies

Monoclonal antibodies (mAbs) are being used to prevent, detect, and treat a broad spectrum of malignancies and infectious and autoimmune diseases. Over the past few years, the market for mAbs has grown exponentially. They have become a significant part of many pharmaceutical product lines, and more than 250 therapeutic mAbs are undergoing clinical trials. Ever since the advent of hybridoma technology, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some of the benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies, which are affordable versions of therapeutic antibodies. Along with biosimilars, innovations in antibody engineering have helped to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. In the future, mAbs generated by applying next-generation sequencing (NGS) are expected to become a powerful tool in clinical therapeutics. This article describes the methods of mAb production, pre-clinical and clinical development of mAbs, approved indications targeted by mAbs, and novel developments in the field of mAb research.

The development process of 'fit-for-purpose' imaging biomarkers to characterize the tumor microenvironment

Immune-based treatment approaches are successfully used for the treatment of patients with cancer. While such therapies can be highly effective, many patients fail to benefit. To provide optimal therapy choices and to predict treatment responses, reliable biomarkers for the assessment of immune features in patients with cancer are of significant importance. Biomarkers (BM) that enable a comprehensive and repeatable assessment of the tumor microenvironment (TME), the lymphoid system, and the dynamics induced by drug treatment can fill this gap. Medical imaging, notably positron emission tomography (PET) and magnetic resonance imaging (MRI), providing whole-body imaging BMs, might deliver such BMs. However, those imaging BMs must be well characterized as being 'fit for purpose' for the intended use. This review provides an overview of the key steps involved in the development of 'fit-for-purpose' imaging BMs applicable in drug development, with a specific focus on pharmacodynamic biomarkers for assessing the TME and its modulation by immunotherapy. The importance of the qualification of imaging BMs according to their context of use (COU) as defined by the Food and Drug Administration (FDA) and National Institutes of Health Biomarkers, EndpointS, and other Tools (BEST) glossary is highlighted. We elaborate on how an imaging BM qualification for a specific COU can be achieved.

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.

Effects of Chemical Fixatives on Kinetic Measurements of Biomolecular Interaction on Cell Membrane

Understanding the interaction between ligands and membrane proteins is important for drug design and optimization. Although investigation using live cells is desirable, it is not feasible in some circumstances and cell fixation is performed to reduce cell motion and degradation. This study compared the effects of five fixatives, i.e., formaldehyde vapor (FV), paraformaldehyde (PFA), acetone, methanol, and ethanol, on kinetic measurements via the LigandTracer method. We found that all five fixatives exerted insignificant effects on lectin-glycan interaction. However, antibody-receptor interaction is markedly perturbed by coagulant fixatives. The acetone fixation changed the binding of the anti-human epidermal growth factor receptor 2 (HER2) antibody to HER2 on the cell membrane from a 1:2 to a 1:1 binding model, while methanol and ethanol abolished the antibody binding possibly by removal of the HER2 receptors on the cell membrane. The capability of binding was retained when methanol fixation was performed at lower temperatures, albeit with a binding model of 1:1 instead. Moreover, whereas cell morphology does not exert a substantial impact on lectin-glycan interaction, it can indeed modify the binding model of antibody-receptor interaction. Our results provided insights into the selection of fixatives for cell-based kinetic studies.

Non-specific irreversible 89Zr-mAb uptake in tumours: evidence from biopsy-proven target-negative tumours using 89Zr-immuno-PET

BACKGROUND

Distribution of mAbs into tumour tissue may occur via different processes contributing differently to the 89Zr-mAb uptake on PET. Target-specific binding in tumours is of main interest; however, non-specific irreversible uptake may also be present, which influences quantification. The aim was to investigate the presence of non-specific irreversible uptake in tumour tissue using Patlak linearization on 89Zr-immuno-PET data of biopsy-proven target-negative tumours. Data of two studies, including target status obtained from biopsies, were retrospectively analysed, and Patlak linearization provided the net rate of irreversible uptake (Ki).

RESULTS

Two tumours were classified as CD20-negative and two as CD20-positive. Four tumours were classified as CEA-negative and nine as CEA-positive. Ki values of CD20-negative (0.43 µL/g/h and 0.92 µL/g/h) and CEA-negative tumours (mdn = 1.97 µL/g/h, interquartile range (IQR) = 1.50-2.39) were higher than zero. Median Ki values of target-negative tumours were lower than CD20-positive (1.87 µL/g/h and 1.90 µL/g/h) and CEA-positive tumours (mdn = 2.77 µL/g/h, IQR = 2.11-3.65).

CONCLUSION

Biopsy-proven target-negative tumours showed irreversible uptake of 89Zr-mAbs measured in vivo using 89Zr-immuno-PET data, which suggests the presence of non-specific irreversible uptake in tumours. Consequently, for 89Zr-immuno-PET, even if the target is absent, a tumour-to-plasma ratio always increases over time.

A trispecific antibody induces potent tumor-directed T-cell activation and antitumor activity by CD3/CD28 co-engagement

Aim: A novel CD19xCD3xCD28 trispecific antibody with a tandem single-chain variable fragments (scFv) structure was developed for the treatment of B-cell malignancies. Methods: The trispecific antibody in inducing tumor-directed T-cell activation and cytotoxicity was evaluated in vitro and in vivo and compared with its bispecific counterpart BiTE-CD19xCD3 lacking a CD28-targeting domain. Results: The trispecific antibody with a co-stimulatory domain exhibited augmented T-cell activation and memory T-cell differentiation capability and it induced faster tumor cell lysis than the bispecific antibody. RNAseq analysis revealed that the trispecific antibody modulates CD3/TCR complex-derived signal and upregulates antiapoptotic factors to influence the survival of T cells. Conclusion: By CD3/CD28 co-engagement, the trispecific antibody demonstrated its advantages in T-cell immunity and potential use as a more powerful and long-lasting T-cell engager.

Serum immunoglobulin or albumin binding single-domain antibodies that enable tailored half-life extension of biologics in multiple animal species

Single-domain antibody fragments (sdAbs) can be isolated from heavy-chain-only antibodies that occur in camelids or the heavy chain of conventional antibodies, that also occur in camelids. Therapeutic application of sdAbs is often complicated by their low serum half-life. Fusion to sdAb that bind to long-lived serum proteins albumin or IgG can prolong serum half-life of fusion partners. Such studies mostly focused on human application. For half-life prolongation in multiple animal species novel species cross-reacting sdAb are needed. We here describe the isolation from immunized llamas of sdAbs G6 and G13 that bound IgG of 9-10 species analysed, including horse, dog, cat, and swine, as well as sdAb A12 that bound horse, dog, swine and cat albumin. A12 bound albumin with 13 to 271 nM affinity dependent on the species. G13 affinity was difficult to determine by biolayer interferometry due to low and heterogeneous signals. G13 and G6 compete for the same binding domain on Fab fragments. Furthermore, they both lack the hallmark residues typical of camelid sdAbs derived from heavy-chain antibodies and had sequence characteristics typical of human sdAbs with high solubility and stability. This suggests they are derived from conventional llama antibodies. They most likely bind IgG through pairing with VL domains at the VH-VL interface rather than a paratope involving complementarity determining regions. None of the isolated sdAb interfered with FcRn binding to albumin or IgG, and thus do not prevent endosomal albumin/IgG-sdAb complex recycling. Fusions of albumin-binding sdAb A12 to several tetanus neurotoxin (TeNT) binding sdAbs prolonged the terminal serum half-life in piglets to about 4 days, comparable to authentic swine albumin. However, G13 conferred a much lower half-life of 0.84 days. Similarly, in horse, G13 prolonged half-life to only 1.2 days whereas A12 fused to two TeNT binding domains (T6T16A12) had a half-life of 21 days. The high half-life of T6T16A12, which earlier proved to be a highly potent TeNT antitoxin, further supports its therapeutic value. Furthermore, we have identified several additional sdAbs that enable tailored half-life extension of biologicals in multiple animal species.

Molecular surface descriptors to predict antibody developability: sensitivity to parameters, structure models, and conformational sampling

In silico assessment of antibody developability during early lead candidate selection and optimization is of paramount importance, offering a rapid and material-free screening approach. However, the predictive power and reproducibility of such methods depend heavily on the selection of molecular descriptors, model parameters, accuracy of predicted structure models, and conformational sampling techniques. Here, we present a set of molecular surface descriptors specifically designed for predicting antibody developability. We assess the performance of these descriptors by benchmarking their correlations with an extensive array of experimentally determined biophysical properties, including viscosity, aggregation, hydrophobic interaction chromatography, human pharmacokinetic clearance, heparin retention time, and polyspecificity. Further, we investigate the sensitivity of these surface descriptors to methodological nuances, such as the choice of interior dielectric constant, hydrophobicity scales, structure prediction methods, and the impact of conformational sampling. Notably, we observe systematic shifts in the distribution of surface descriptors depending on the structure prediction method used, driving weak correlations of surface descriptors across structure models. Averaging the descriptor values over conformational distributions from molecular dynamics mitigates the systematic shifts and improves the consistency across different structure prediction methods, albeit with inconsistent improvements in correlations with biophysical data. Based on our benchmarking analysis, we propose six in silico developability risk flags and assess their effectiveness in predicting potential developability issues for a set of case study molecules.

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.

A Critical Analysis of the FDA's Omics-Driven Pharmacodynamic Biomarkers to Establish Biosimilarity

Demonstrating biosimilarity entails comprehensive analytical assessment, clinical pharmacology profiling, and efficacy testing in patients for at least one medical indication, as required by the U.S. Biologics Price Competition and Innovation Act (BPCIA). The efficacy testing can be waived if the drug has known pharmacodynamic (PD) markers, leaving most therapeutic proteins out of this concession. To overcome this, the FDA suggests that biosimilar developers discover PD biomarkers using omics technologies such as proteomics, glycomics, transcriptomics, genomics, epigenomics, and metabolomics. This approach is redundant since the mode-action-action biomarkers of approved therapeutic proteins are already available, as compiled in this paper for the first time. Other potential biomarkers are receptor binding and pharmacokinetic profiling, which can be made more relevant to ensure biosimilarity without requiring biosimilar developers to conduct extensive research, for which they are rarely qualified.

Substantial heterogeneity of inflammatory cytokine production and its inhibition by a triple cocktail of toll-like receptor blockers in early sepsis

Introduction

Early sepsis is a life-threatening immune dysregulation believed to feature a "cytokine storm" due to activation of pattern recognition receptors by pathogen and danger associated molecular patterns. However, treatments with single toll-like receptor (TLR) blockers have shown no clinical benefit. We speculated that sepsis patients at the time of diagnosis are heterogeneous in relation to their cytokine production and its potential inhibition by a triple cocktail of TLR blockers. Accordingly, we analyzed inflammatory cytokine production in whole blood assays from early sepsis patients and determined the effects of triple TLR-blockade.

Methods

Whole blood of 51 intensive care patients sampled within 24h of meeting Sepsis-3 criteria was incubated for 6h without or with specific TLR2, 4, and 7/8 stimuli or suspensions of heat-killed S. aureus or E. coli bacteria as pan-TLR challenges, and also with a combination of monoclonal antibodies against TLR2 and 4 and chloroquine (endosomal TLR inhibition), subsequent to dose optimization. Concentrations of tumor necrosis factor (TNF), Interleukin(IL)-6, IL-8, IL-10, IL-1α and IL-1β were measured (multiplex ELISA) before and after incubation. Samples from 11 sex and age-matched healthy volunteers served as controls and for dose-finding studies.

Results

Only a fraction of sepsis patient samples revealed ongoing cytokine production ex vivo despite sampling within 24 h of first meeting Sepsis-3 criteria. In dose finding studies, inhibition of TLR2, 4 and endosomal TLRs reliably suppressed cytokine production to specific TLR agonists and added bacteria. However, inflammatory cytokine production ex vivo was only suppressed in the high cytokine producing samples but not in the majority. The suppressive response to TLR-blockade correlated both with intraassay inflammatory cytokine production (r=0.29-0.68; p<0.0001-0.04) and cytokine baseline concentrations (r=0.55; p<0.0001).

Discussion

Upon meeting Sepsis-3 criteria for less than 24 h, a mere quarter of patient samples exhibits a strong inflammatory phenotype, as characterized by increased baseline inflammatory cytokine concentrations and a stark TLR-dependent increase upon further ex vivo incubation. Thus, early sepsis patient cohorts as defined by Sepsis-3 criteria are very heterogeneous in regard to inflammation. Accordingly, proper ex vivo assays may be useful in septic individuals before embarking on immunomodulatory treatments.

Mirikizumab Pharmacokinetics in Patients with Moderately to Severely Active Ulcerative Colitis: Results from Phase III LUCENT Studies

BACKGROUND AND OBJECTIVE

Mirikizumab is a humanized anti-interleukin-23-p19 monoclonal antibody being developed for ulcerative colitis and Crohn's disease. This analysis characterized mirikizumab pharmacokinetics using phase II and III trial data from patients with moderately to severely active ulcerative colitis.

METHODS

Serum pharmacokinetic data in patients receiving mirikizumab 50-1000 mg intravenously every 4 weeks as induction treatment and mirikizumab 200 mg subcutaneously every 4 or 12 weeks as maintenance treatment across three trials (N = 1362) were analyzed using non-linear mixed-effects modeling. Covariate effects on mirikizumab exposure were evaluated using simulation-based estimations.

RESULTS

Mirikizumab pharmacokinetics was best described by a linear two-compartment model with first-order absorption. Clearance, volume of distribution for central and peripheral compartments, and half-life were estimated at approximately 0.022 L/h (linear), 3.11 L and 1.69 L, and 9.5 days, respectively. Statistically significant effects of body weight and serum albumin levels on clearance, body weight on central and peripheral volumes of distribution, and body mass index on bioavailability were observed but effects were small relative to random inter-individual variability (% coefficient of variation: 18-64%). The subcutaneous bioavailability of mirikizumab was 48%.

CONCLUSIONS

Mirikizumab displayed pharmacokinetic characteristics typical of a monoclonal antibody where clearance increased with body weight and decreased with the albumin level, and bioavailability decreased with body mass index. These effects were small relative to random variability, indicating that a dose adjustment for patient factors is not required.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02589665 (28 October, 2015), NCT03518086 (8 May, 2018), NCT03524092 (14 May, 2018).

Tackling TNF-α in autoinflammatory disorders and autoimmune diseases: From conventional to cutting edge in biologics and RNA- based nanomedicines

Autoinflammatory disorders and autoimmune diseases result from abnormal deviations of innate and adaptive immunity that heterogeneously affect organs and clinical phenotypes. Despite having etiologic and phenotypic differences, these two conditions share the onset of an aberrant inflammatory process. Targeting the main drivers controlling inflammation is useful to treat both autoimmune and autoinflammatory syndromes. TNF-α is a major player in the inflammatory immune response, and anti-TNF-α antibodies have been a revolutionary treatment in many autoimmune disorders. However, production difficulties and high development costs hinder their implementation, and accessibility to their use is still limited. Innovative strategies aimed at overcoming the limitations associated with anti-TNF-α antibodies are being explored, including RNA-based therapies. Here we summarize the central role of TNF-α in immune disorders and how anti-TNF-based immunotherapies changed the therapeutic landscape, albeit with important limitations related to side effects, tolerance, and resistance to therapies. We then outline how nanotechnology has provided the final momentum for the use of nucleic acids in the treatment of autoimmune and autoinflammatory diseases, with a focus on inflammatory bowel diseases (IBDs). The example of IBDs allows the evaluation and discussion of the nucleic acids-based treatments that have been developed, to identify the role that innovative approaches possess in view of the treatment of autoinflammatory disorders and autoimmune diseases.

Dosimetry of a Novel 111Indium-Labeled Anti-P-Cadherin Monoclonal Antibody (FF-21101) in Non-Human Primates

P-cadherin is associated with a wide range of tumor types, making it an attractive therapeutic target. FF-21101 is a human-mouse chimeric monoclonal antibody (mAb) directed against human P-cadherin, which has been radioconjugated with indium-111 (111In) utilizing a DOTA chelator. We investigated the biodistribution of FF-21101(111In) in cynomolgus macaques and extrapolated the results to estimate internal radiation doses of 111In- and yttrium-90 (90Y)-FF-21101 for targeted radioimmunotherapy in humans. Whole-body planar and SPECT imaging were performed at 0, 2, 24, 48, 72, 96, and 120 h post-injection, using a dual-head gamma camera. Volumes of interest of identifiable source organs of radioactivity were defined on aligned reference CT and serial SPECT images. Organs with the highest estimated dose values (mSv/MBq) for FF-21101(111In) were the lungs (0.840), spleen (0.816), liver (0.751), kidneys (0.629), and heart wall (0.451); and for FF-21101(90Y) dose values were: lungs (10.49), spleen (8.21), kidneys (5.92), liver (5.46), and heart wall (2.61). FF-21101(111In) exhibits favorable biodistribution in cynomolgus macaques and estimated human dosimetric characteristics. Data obtained in this study were used to support the filing of an investigational new drug application with the FDA for a Phase I clinical trial.

Degradation of extracellular and membrane proteins in targeted therapy: Status quo and quo vadis

Targeted protein degradation (TPD) strategies, such as proteolysis-targeting chimeras (PROTACs) only work for intracellular protein degradation because they involve the intracellular protein degradation machinery. Several new technologies have emerged in recent years for TPD of extracellular and membrane proteins. Even though some progress has been demonstrated in the extracellular and membrane protein degradation field, the application of these technologies is still in its infancy. In this review, we survey the therapeutic potential of existing technologies by summarizing and reviewing discoveries and hurdles in extracellular and membrane protein-of-interest (POI) degradation.

Therapeutic drug monitoring of immune checkpoint inhibitors: based on their pharmacokinetic properties and biomarkers

As a new means of oncology treatment, immune checkpoint inhibitors (ICIs) can improve survival rates in patients with resistant or refractory tumors. However, there are obvious inter-individual differences in the unsatisfactory response rate, drug resistance rate and the occurrence of immune-related adverse events (irAE). These questions have sparked interest in researchers looking for a way to screen sensitive populations and predict efficacy and safety. Therapeutic drug monitoring (TDM) is a way to ensure the safety and effectiveness of medication by measuring the concentration of drugs in body fluids and adjusting the medication regimen. It has the potential to be an adjunctive means of predicting the safety and efficacy of ICIs treatment. In this review, the author outlined the pharmacokinetic (PK) characteristics of ICIs in patients. The feasibility and limitations of TDM of ICIs were discussed by summarizing the relationships between the pharmacokinetic parameters and the efficacy, toxicity and biomarkers.

Mechanism-based pharmacokinetic and pharmacodynamic modeling for bispecific antibodies: challenges and opportunities

INTRODUCTION

Unlike conventional antibodies, bispecific antibodies (bsAbs) are engineered antibody- or antibody fragment-based molecules that can simultaneously recognize two different epitopes or antigens. Over the past decade, there has been an explosion of bsAbs being developed across therapeutic areas. Development of bsAbs presents unique challenges and mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) modeling has served as a powerful tool to optimize their development and realize their clinical utility.

AREAS COVERED

In this review, the guiding principles and case examples of how fit-for-purpose, mechanism-based PK/PD models have been applied to answer questions commonly encountered in bsAb development are presented. Such models characterize the key pharmacological elements of bsAbs, and they can be utilized for model-informed drug development. We also include the discussion of challenges, knowledge gaps and future direction for such models.

EXPERT OPINION

Mechanistic PK/PD modeling is a powerful tool to support the development of bsAbs. These models can be extrapolated to predict treatment outcomes based on mechanisms of action (MoA) and clinical observations to form positive learn-and-confirm cycles during drug development, due to their abilities to differentiate system- and drug-specific parameters. Meanwhile, the models should keep being adapted according to novel drug design and MoA, providing continuous opportunities for model-informed drug development.

Successful regression of newly formed corneal neovascularization by subconjunctival injection of bevacizumab in patients with chemical burns

Purpose

To investigate the effect and timing of subconjunctival bevacizumab injection on inhibiting corneal neovascularization (CorNV) in patients after chemical burns.

Methods

Patients with CorNV secondary to chemical burns were involved. Two subconjunctival injections of bevacizumab (2.5 mg/0.1 mL per involved quadrant) with an interval of 4 weeks were administered, and followed up a year. The area occupied by neovascular vessels (NA), accumulative neovascular length (NL), mean neovascular diameter (ND), best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were evaluated. Complication was also recorded.

Results

Eleven patients with CorNV were involved. Eight patients had a history of surgery (four had amniotic grafts, one had keratoplasty, and three had amniotic grafts and keratoplasty). Decreasing in NA, NL, and ND were statistically significant at each time point compared to the baseline (p < 0.01). CorNV that developed within 1 month was considerably regressed, and vessels with fibrovascular membranes were found to be narrower and shorter than pretreatment. BCVA improved in five patients (from one to five lines), remained unchanged in five patients, and decreased in one patient compared to pretreatment.

Conclusion

Subconjunctival bevacizumab injection has a particular potential for the regression of CorNV, especially newly formed within 1 month in patients after chemical burns.

Snake Antivenoms-Toward Better Understanding of the Administration Route

Envenomations induced by animal bites and stings constitute a significant public health burden. Even though a standardized protocol does not exist, parenterally administered polyclonal antivenoms remain the mainstay in snakebite therapy. There is a prevailing opinion that their application by the i.m. route has poor efficacy and that i.v. administration should preferentially be chosen in order to achieve better accomplishment of the antivenom therapeutic activity. Recently, it has been demonstrated that neutralization not only in the systemic circulation but also in the lymphatic system might be of great importance for the clinical outcome since it represents another relevant body compartment through which the absorption of the venom components occurs. In this review, the present-day and summarized knowledge of the laboratory and clinical findings on the i.v. and i.m. routes of antivenom administration is provided, with a special emphasis on the contribution of the lymphatic system to the process of venom elimination. Until now, antivenom-mediated neutralization has not yet been discussed in the context of the synergistic action of both blood and lymph. A current viewpoint might help to improve the comprehension of the venom/antivenom pharmacokinetics and the optimal approach for drug application. There is a great need for additional dependable, practical, well-designed studies, as well as more practice-related experience reports. As a result, opportunities for resolving long-standing disputes over choosing one therapeutic principle over another might be created, improving the safety and effectiveness of snakebite management.

Assessment of the influence of Fc-γ receptor polymorphisms on biologics' pharmacokinetics in Tunisian rheumatoid arthritis patients

AIMS

This study aims to determine whether a modification in Fc-γ receptors' (FcgRs) affinity to Fc portion, caused by single nucleotide polymorphisms such as rs1801274-R131H FcgRIIa, rs396991-F158V FcgRIIIa and NA1/NA2-FcgRIIIb, might impact clearance of therapeutic monoclonal antibodies and thus serum drug levels and the development of anti-drug antibodies.

METHODS

A cross sectional, multicentral and noninterventional study was conducted in Tunisian RA patients treated with rituximab (RTX), etanercept (ETA), infliximab (IFX) and adalimumab (ADL). Serum drug level (SDL) of the different biologics and ADA against them were measured. All patients were genotyped for the 3 FcgR single nucleotide polymorphisms.

RESULTS

A total of 81 patients were included: 47 were under tumour necrosis factor inhibitors (18 ETA, 13 ADL and 16 IFX), and 34 were under RTX. Regardless of the type of biotherapy, SDL was in therapeutic range, in 35 patients (43.2%), of whom only 1 was treated with RTX. Fourteen patients (22.2%) developed ADA, but none of the patients treated with ETA had detectable ADA levels. There was no association between SDL positivity and FcgR polymorphisms. However, the high affinity FcgR2A 131 H/H receptor was statistically more prevalent in patients with detectable ADA treated with ADL, IFX and RTX (P = .018). The same result was obtained in the monoclonal antibody tumour necrosis factor inhibitor subgroup (n = 29, P = .022) as well as in patients treated only with IFX (n = 16, P = .029).

CONCLUSION

Our work supports the hypothesis of an impact of FcgR single nucleotide polymorphisms on biologics' immunogenicity, particularly FcgR R131H polymorphism, but further studies with larger cohorts need to be undertaken to confirm these results.

Validation of simplified uptake measures against dynamic Patlak Ki for quantification of lesional 89Zr-Immuno-PET antibody uptake

PURPOSE

Positron emission tomography imaging of zirconium-89-labelled monoclonal antibodies (89Zr-Immuno-PET) allows for visualisation and quantification of antibody uptake in tumours in vivo. Patlak linearization provides distribution volume (VT) and nett influx rate (Ki) values, representing reversible and irreversible uptake, respectively. Standardised uptake value (SUV) and tumour-to-plasma/tumour-to-blood ratio (TPR/TBR) are often used, but their validity depends on the comparability of plasma kinetics and clearances. This study assesses the validity of SUV, TPR and TBR against Patlak Ki for quantifying irreversible 89Zr-Immuno-PET uptake in tumours.

METHODS

Ten patients received 37 MBq 10 mg 89Zr-anti-EGFR with 500 mg/m2 unlabelled mAbs. Five patients received two doses of 37 MBq 89Zr-anti-HER3: 8-24 mg for the first administration and 24 mg-30 mg/kg for the second. Seven tumours from four patients showed 89Zr-anti-EGFR uptake, and 18 tumours from five patients showed 89Zr-anti-HER3 uptake. SUVpeak, TPRpeak and TBRpeak values were obtained from one to six days p.i. Patlak linearization was applied to tumour time activity curves and plasma samples to obtain Ki.

RESULTS

For 89Zr-anti-EGFR, there was a small variability along the linear regression line between SUV (- 0.51-0.57), TPR (- 0.06‒0.11) and TBR (- 0.13‒0.16) on day 6 versus Ki. Similar doses of 89Zr-anti-HER3 showed similar variability for SUV (- 1.3‒1.0), TPR (- 1.1‒0.53) and TBR (- 1.5‒0.72) on day 5 versus Ki. However, for the second administration of 89Zr-anti-HER3 with a large variability in administered mass doses, SUV showed a larger variability (- 1.4‒2.3) along the regression line with Ki, which improved when using TPR (- 0.38-0.32) or TBR (- 0.56‒0.46).

CONCLUSION

SUV, TPR and TBR at late time points were valid for quantifying irreversible lesional 89Zr-Immuno-PET uptake when constant mass doses were administered. However, for variable mass doses, only TPR and TBR provided reliable values for irreversible uptake, but not SUV, because SUV does not take patient and mass dose-specific plasma clearance into account.

Radiolabelled Extracellular Vesicles as Imaging Modalities for Precise Targeted Drug Delivery

Extracellular vesicles (ECVs) have been abandoned as bio-inspired drug delivery systems (DDS) in the biomedical field. ECVs have a natural ability to cross over extracellular and intracellular barriers, making them superior to manufactured nanoparticles. Additionally, they have the ability to move beneficial biomolecules among far-flung bodily cells. These advantages and the accomplishment of favorable in vivo results convincingly show the value of ECVs in medication delivery. The usage of ECVs is constantly being improved, as it might be difficult to develop a consistent biochemical strategy that is in line with their useful clinical therapeutic uses. Extracellular vesicles (ECVs) have the potential to enhance the therapy of diseases. Imaging technologies, particularly radiolabelled imaging, have been exploited for non-invasive tracking to better understand their in vivo activity.

Influence of Genetics on the Response to Omalizumab in Patients with Severe Uncontrolled Asthma with an Allergic Phenotype

Omalizumab is a monoclonal antibody indicated for the treatment of severe uncontrolled asthma with an allergic phenotype. Its effectiveness could be influenced by clinical variables and single nucleotide polymorphisms (SNPs) in one or more of the genes involved in the mechanism of action and process of response to omalizumab, and these could be used as predictive biomarkers of response. We conducted an observational retrospective cohort study that included patients with severe uncontrolled allergic asthma treated with omalizumab in a tertiary hospital. Satisfactory response after 12 months of treatment was defined as (1) Reduction ≥ 50% of exacerbations or no exacerbations, (2) Improvement of lung function ≥ 10% FEV1, and (3) Reduction ≥ 50% of OCS courses or no OCS. Polymorphisms in the FCER1A (rs2251746, rs2427837), FCER1B (rs1441586, rs573790, rs1054485, rs569108), C3 (rs2230199), FCGR2A (rs1801274), FCGR2B (rs3219018, rs1050501), FCGR3A (rs10127939, rs396991), IL1RL1 (rs1420101, rs17026974, rs1921622), and GATA2 (rs4857855) genes were analyzed by real-time polymerase chain reaction (PCR) using TaqMan probes. A total of 110 patients under treatment with omalizumab were recruited. After 12 months of treatment, the variables associated with a reduction in exacerbations were the absence of polyposis (odds ratio [OR] = 4.22; 95% confidence interval [CI] = 0.95-19.63), IL1RL1 rs17026974-AG (OR = 19.07; 95% CI = 1.27-547), and IL1RL1 rs17026974-GG (OR = 16.76; 95% CI = 1.22-438.76). Reduction in oral corticosteroids (OCS) was associated with age of starting omalizumab treatment (OR = 0.95; 95% CI = 0.91-0.99) and blood eosinophil levels > 300 cells/µL (OR = 2.93; 95% CI = 1.01-9.29). Improved lung function showed a relationship to the absence of chronic obstructive pulmonary disease (COPD) (OR = 12.16; 95% CI = 2.45-79.49), FCGR2B rs3219018-C (OR = 8.6; 95% CI = 1.12-117.15), GATA2 rs4857855-T (OR = 15.98; 95% CI = 1.52-519.57) and FCGR2A rs1801274-G (OR = 13.75; 95% CI = 2.14-142.68; AG vs. AA and OR = 7.46; 95% CI = 0.94-89.12; GG vs. AA). Meeting one response criterion was related to FCER1A rs2251746-TT (OR = 24; 95% CI = 0.77-804.57), meeting two to age of asthma diagnosis (OR = 0.93; 95% CI = 0.88-0.99), and meeting all three to body mass index (BMI) < 25 (OR = 14.23; 95% CI = 3.31-100.77) and C3 rs2230199-C (OR = 3; 95% CI = 1.01-9.92). The results of this study show the possible influence of the polymorphisms studied on the response to omalizumab and the clinical benefit that could be obtained by defining predictive biomarkers of treatment response.

Antibody-mediated protection against symptomatic COVID-19 can be achieved at low serum neutralizing titers

Multiple studies of vaccinated and convalescent cohorts have demonstrated that serum neutralizing antibody (nAb) titers correlate with protection against coronavirus disease 2019 (COVID-19). However, the induction of multiple layers of immunity after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure has complicated the establishment of nAbs as a mechanistic correlate of protection (CoP) and hindered the definition of a protective nAb threshold. Here, we show that a half-life-extended monoclonal antibody (adintrevimab) provides about 50% protection against symptomatic COVID-19 in SARS-CoV-2-naïve adults at serum nAb titers on the order of 1:30. Vaccine modeling results support a similar 50% protective nAb threshold, suggesting that low titers of serum nAbs protect in both passive antibody prophylaxis and vaccination settings. Extrapolation of adintrevimab pharmacokinetic data suggests that protection against susceptible variants could be maintained for about 3 years. The results provide a benchmark for the selection of next-generation vaccine candidates and support the use of broad, long-acting monoclonal antibodies as alternatives or supplements to vaccination in high-risk populations.

Pharmacokinetics of antibodies during pregnancy: General pharmacokinetics and pregnancy related physiological changes (Part 1)

Pharmacokinetics (PK) studies are important to determine a safe and effective dose of both small and large molecule drugs. Intrinsic factors such as pregnancy can substantially alter the PK of a drug. Several PK studies have been published for small molecules administered during pregnancy, but such investigations are scarce for macromolecules including monoclonal and polyclonal antibodies. In this part 1 of 2 reviews, we first provide a general description of macromolecule drugs, the PK differences with small molecules, and current knowledge on their absorption, distribution, metabolism and elimination in non-pregnant subjects. We then review in detail the physiological changes during pregnancy. While some of the physiologic adaptions of pregnancy, for example increased plasma volume and cardiac output, are expected to impact PK of antibody therapeutics, the effects of others, such as increased GFR and altered immune responses are not fully understood. We conclude that further investigations are needed to fully elucidate how pregnancy can impact PK properties of macromolecules.

“Click-to-Clear”: A Strategy to Minimize Radioactivity from the Blood Pool Utilizing Staudinger Ligation

The availability of several bioorthogonal reactions that can proceed selectively and efficiently under physiologically relevant conditions has garnered the interest of biochemists and organic chemists alike. Bioorthogonal cleavage reactions represent the latest innovation in click chemistry. Here, we employed the Staudinger ligation reaction to release radioactivity from immunoconjugates, improving target-to-background ratios. In this proof-of-concept study, model systems, including the anti-HER2 antibody trastuzumab, radioisotope I-131, and a newly synthesized bifunctional phosphine, were used. Staudinger ligation occurred when biocompatible N-glycosyl azides reacted with this radiolabeled immunoconjugate, leading to cleavage of the radioactive label from the molecule. We demonstrated this click cleavage in vitro and in vivo. Biodistribution studies in tumor models showed that radioactivity was eliminated from the bloodstream, thereby improving tumor-to-blood ratios. SPECT imaging revealed that tumors could be visualized with enhanced clarity. Our simple approach represents a novel application of bioorthogonal click chemistry in the development of antibody-based theranostics.

Development of an inhaled anti-TSLP therapy for asthma

Thymic stromal lymphopoietin (TSLP), an epithelial cell-derived cytokine, acts as a key mediator in airway inflammation and modulates the function of multiple cell types, including dendritic cells and group 2 innate lymphoid cells. TSLP plays a role in asthma pathogenesis as an upstream cytokine, and data suggest that TSLP blockade with the anti-TSLP monoclonal antibody, tezepelumab, could be efficacious in a broad asthma population. Currently approved asthma biologic therapies target allergic or eosinophilic disease and require phenotyping; therefore, an unmet need exists for a therapy that can address Type 2 (T2)-high and T2-low inflammation in asthma. All currently approved biologic treatments are delivered intravenously or subcutaneously; an inhaled therapy route that allows direct targeting of the lung with reduced systemic impact may offer advantages. Currently in development, ecleralimab (CSJ117) represents the first inhaled anti-TSLP antibody fragment that binds soluble TSLP and prevents TSLP receptor activation, thereby inhibiting further inflammatory signalling cascades. This anti-TSLP antibody fragment is being developed for patients with severe uncontrolled asthma despite standard of care inhaled therapy. A Phase IIa proof of concept study, using allergen bronchoprovocation as a model for asthma exacerbations, found that ecleralimab was well-tolerated and reduced allergen-induced bronchoconstriction in adult patients with mild asthma. These results suggest ecleralimab may be a promising, new therapeutic class for asthma treatment.

Mechanisms of ADC Toxicity and Strategies to Increase ADC Tolerability

Anti-cancer antibody-drug conjugates (ADCs) aim to expand the therapeutic index of traditional chemotherapy by employing the targeting specificity of monoclonal antibodies (mAbs) to increase the efficiency of the delivery of potent cytotoxic agents to malignant cells. In the past three years, the number of ADCs approved by the Food and Drug Administration (FDA) has tripled. Although several ADCs have demonstrated sufficient efficacy and safety to warrant FDA approval, the clinical use of all ADCs leads to substantial toxicity in treated patients, and many ADCs have failed during clinical development due to their unacceptable toxicity profiles. Analysis of the clinical data has demonstrated that dose-limiting toxicities (DLTs) are often shared by different ADCs that deliver the same cytotoxic payload, independent of the antigen that is targeted and/or the type of cancer that is treated. DLTs are commonly associated with cells and tissues that do not express the targeted antigen (i.e., off-target toxicity), and often limit ADC dosage to levels below those required for optimal anti-cancer effects. In this manuscript, we review the fundamental mechanisms contributing to ADC toxicity, we summarize common ADC treatment-related adverse events, and we discuss several approaches to mitigating ADC toxicity.

A pH-dependent anti-CD47 antibody that selectively targets solid tumors and improves therapeutic efficacy and safety

BACKGROUND

The antiphagocytic molecule CD47 is overexpressed in a wide variety of cancer cells, and antibodies targeting CD47 for cancer therapies are currently under intensive investigation. However, owing to the ubiquitous expression of CD47 on healthy cells, anti-CD47 therapies often achieve only weak therapeutic benefits and can induce severe side effects. Here, we report the generation of a pH-dependent anti-CD47 antibody (BC31M4) which selectively binds to tumors under the acidic solid tumor microenvironment.

METHODS

BC31M4 was generated using antibody phage display and a pH-dependent selection strategy. The pH-dependent binding and blocking activities of BC31M4 were verified using in vitro assays, and the structural basis of the pH-dependent binding property was characterized. BC31M4's antitumor effect was confirmed by both phagocytosis assays and studies in xenograft models. The tumor selectivity, mechanism of action, PK properties, side effects, and therapeutic efficacy were further evaluated in humanized (hCD47 and its receptor hSIRPα) immunocompetent syngeneic mouse models.

RESULTS

The crystal structure reveals that two histidines locate within the CDRs of the light chain directly contribute to the pH-dependent binding of BC31M4. BC31M4 promotes macrophage phagocytosis of tumor cells more potently at acidic-pH than at physiological-pH. Our hCD47/hSIRPα humanized syngeneic mouse model results demonstrated that BC31M4 selectively accumulates in tumors but not in normal tissues. BC31M4 causes minimal side effects and exhibits superior PK properties as compared to the other examined anti-CD47 antibodies. When combined with adoptive T cell transfer, BC31M4 efficiently promotes adaptive immune responses against tumors and also induces immune memory. Moreover, we show that BC31M4's antitumor effects rely on an Fc that mediates strong effector functions.

CONCLUSIONS

Our study illustrates that the development of a tumor-selective, pH-dependent anti-CD47 antibody safely confers strong therapeutic effects against solid tumors, thus providing a promising therapeutic strategy to overcome the challenges of anti-CD47 therapy.

Utility of in silico prediction of target suppression for antibodies against soluble targets: static versus dynamic models

PURPOSE

Antibodies that bind soluble targets such as cytokines belong to an important class of immunotherapies. Target levels can significantly accumulate after antibody administration due to formation of antibody-target complex, accompanied with suppression in free target which is often difficult to measure. Being a surrogate for pharmacodynamic activity, free target suppression is often predicted using in silico tools. The objective of this work is to illustrate the utility of modelling and to compare static versus dynamic models in the prediction of free target suppression.

METHODS

Using binding principles, we have derived a static equation to predict free target suppression at steady state (FTSS). This equation operates with five input parameters and accounts for target accumulation over time. Its predictivity was compared to a dynamic model and to other existing metrics in literature via simulations and assumptions were illustrated.

RESULTS

We demonstrated the utility of in silico tools in prediction of free target suppression using static and dynamic models and clarified the assumptions in key input parameters and their limitations. Predicted values using the FTSS equation correlate very well with those from the dynamic model at level > 20% target suppression, relevant for antagonistic antibodies.

CONCLUSION

In silico tools are needed to predict target suppression by antibody drugs. Static or dynamic models can be used dependant on the scope, available data and undertaken assumptions. These tools can be used to guide discovery and development of antibodies and has the potential to reduce clinical failure.

Mechanisms of unusual response to lipid-lowering therapy: PCSK9 inhibition

The efficacy of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition has broadened lipid-lowering therapy thus providing decreased risk in atherosclerotic cardiovascular disease. Unfortunately, the widespread use of PCSK9 inhibitors (PCSK9i), ie, monoclonal antibodies, has led to the findings of unusual responsiveness, ie, a phenomenon defined as an LDL-C reduction of <30% vs the average LDL-C reduction efficacy of 50-60%. This unusual responsiveness to PCSK9i is attributable to several factors, ie, lack of adherence, impaired absorption, poor distribution or early elimination as well as abnormal effects of PCSK9i in the presence of anti-antibodies or mutations in PCSK9 and LDLR. Unexpectedly increased lipoprotein (Lp)(a) also appear to contribute to the unusual responsiveness scenario. Identification of these responses and mechanisms underlying them are essential for effective management of LDL-C and cardiovascular risk. In this review, we describe plausible reasons underlying this phenomenon supported by findings of clinical trials. We also elaborate on the need for education and regular follow-up to improve adherence. Collectively, the review provides a summary of the past, present, and future of mechanisms and countermeasures revolving around unusual responses to PCSK9i therapy.

Half-Life Extension and Biodistribution Modulation of Biotherapeutics via Red Blood Cell Hitch-Hiking with Novel Anti-Band 3 Single-Domain Antibodies

Small therapeutic proteins are receiving increased interest as therapeutic drugs; however, their clinical success has been limited due to their rapid elimination. Here, we report a half-life extension strategy via strategy via red blood cell red blood cell (RBC) hitch-hiking. This manuscript details the development and characterization of novel anti-RBC single-domain antibodies (sdAbs), their genetic fusion to therapeutic antibody fragments (TAF) as bispecific fusion constructs, and their influence on TAF pharmacokinetics and biodistribution. Several sdAbs specific to the band 3 antigen were generated via phage-display technology. Binding affinity to RBCs was assessed via flow cytometry. Affinity maturation via random mutagenesis was carried out to improve the binding affinity of the sdAbs. Bi-specific constructs were generated by fusing the anti-RBC sdAbs with anti-tissue necrosis factor alpha (TNF-α) TAF via the use of a glycine-serine flexible linker, and assessments for binding were performed via enzyme-linked immunosorbent assay and flow cytometry. Pharmacokinetics of anti-RBC sdAbs and fusion constructs were evaluated following intravenous bolus dosing in mice at a 1 mg/kg dose. Two RBC-binding sdAbs, RB12 and RE8, were developed. These two clones showed high binding affinity to human RBC with an estimated K_D of 17.7 nM and 23.6 nM and low binding affinity to mouse RBC with an estimated K_D of 335 nM and 528 nM for RB12 and RE8, respectively. Two derivative sdAbs, RMA1, and RMC1, with higher affinities against mouse RBC, were generated via affinity maturation (K_D of 66.9 nM and 30.3 nM, respectively). Pharmacokinetic investigations in mice demonstrated prolonged circulation half-life of an anti-RBC-TNF-α bispecific construct (75 h) compared to a non-RBC binding control (1.3 h). In summary, the developed anti-RBC sdAbs and fusion constructs have demonstrated high affinity in vitro, and sufficient half-life extension in vivo.

Half-Life Extension and Biodistribution Modulation of Biotherapeutics via Red Blood Cell Hitch-Hiking with Novel Anti-Band 3 Single-Domain Antibodies

Small therapeutic proteins are receiving increased interest as therapeutic drugs; however, their clinical success has been limited due to their rapid elimination. Here, we report a half-life extension strategy via strategy via red blood cell red blood cell (RBC) hitch-hiking. This manuscript details the development and characterization of novel anti-RBC single-domain antibodies (sdAbs), their genetic fusion to therapeutic antibody fragments (TAF) as bispecific fusion constructs, and their influence on TAF pharmacokinetics and biodistribution. Several sdAbs specific to the band 3 antigen were generated via phage-display technology. Binding affinity to RBCs was assessed via flow cytometry. Affinity maturation via random mutagenesis was carried out to improve the binding affinity of the sdAbs. Bi-specific constructs were generated by fusing the anti-RBC sdAbs with anti-tissue necrosis factor alpha (TNF-α) TAF via the use of a glycine-serine flexible linker, and assessments for binding were performed via enzyme-linked immunosorbent assay and flow cytometry. Pharmacokinetics of anti-RBC sdAbs and fusion constructs were evaluated following intravenous bolus dosing in mice at a 1 mg/kg dose. Two RBC-binding sdAbs, RB12 and RE8, were developed. These two clones showed high binding affinity to human RBC with an estimated K_D of 17.7 nM and 23.6 nM and low binding affinity to mouse RBC with an estimated K_D of 335 nM and 528 nM for RB12 and RE8, respectively. Two derivative sdAbs, RMA1, and RMC1, with higher affinities against mouse RBC, were generated via affinity maturation (K_D of 66.9 nM and 30.3 nM, respectively). Pharmacokinetic investigations in mice demonstrated prolonged circulation half-life of an anti-RBC-TNF-α bispecific construct (75 h) compared to a non-RBC binding control (1.3 h). In summary, the developed anti-RBC sdAbs and fusion constructs have demonstrated high affinity in vitro, and sufficient half-life extension in vivo.

Antibody-oligonucleotide conjugate achieves CNS delivery in animal models for spinal muscular atrophy

Antisense oligonucleotides (ASOs) have emerged as one of the most innovative new genetic drug modalities. However, their high molecular weight limits their bioavailability for otherwise-treatable neurological disorders. We investigated conjugation of ASOs to an antibody against the murine transferrin receptor, 8D3130, and evaluated it via systemic administration in mouse models of the neurodegenerative disease spinal muscular atrophy (SMA). SMA, like several other neurological and neuromuscular diseases, is treatable with single-stranded ASOs that modulate splicing of the survival motor neuron 2 (SMN2) gene. Administration of 8D3130-ASO conjugate resulted in elevated levels of bioavailability to the brain. Additionally, 8D3130-ASO yielded therapeutic levels of SMN2 splicing in the central nervous system of adult human SMN2-transgenic (hSMN2-transgenic) mice, which resulted in extended survival of a severely affected SMA mouse model. Systemic delivery of nucleic acid therapies with brain-targeting antibodies offers powerful translational potential for future treatments of neuromuscular and neurodegenerative diseases.

A Zika virus-specific IgM elicited in pregnancy exhibits ultrapotent neutralization

Congenital Zika virus (ZIKV) infection results in neurodevelopmental deficits in up to 14% of infants born to ZIKV-infected mothers. Neutralizing antibodies are a critical component of protective immunity. Here, we demonstrate that plasma IgM contributes to ZIKV immunity in pregnancy, mediating neutralization up to 3 months post-symptoms. From a ZIKV-infected pregnant woman, we isolated a pentameric ZIKV-specific IgM (DH1017.IgM) that exhibited ultrapotent ZIKV neutralization dependent on the IgM isotype. DH1017.IgM targets an envelope dimer epitope within domain II. The epitope arrangement on the virion is compatible with concurrent engagement of all ten antigen-binding sites of DH1017.IgM, a solution not available to IgG. DH1017.IgM protected mice against viremia upon lethal ZIKV challenge more efficiently than when expressed as an IgG. Our findings identify a role for antibodies of the IgM isotype in protection against ZIKV and posit DH1017.IgM as a safe and effective candidate immunotherapeutic, particularly during pregnancy.

Immunotherapies for the Treatment of Drug Addiction

Substance use disorders (SUD) are a serious public health concern globally. Existing treatment platforms suffer from a lack of effectiveness. The development of immunotherapies against these substances of abuse for both prophylactic and therapeutic use has gained tremendous importance as an alternative and/or supplementary to existing therapies. Significant development has been made in this area over the last few decades. Herein, we highlight the vaccine and other biologics development strategies, preclinical, clinical updates along with challenges and future directions. Articles were searched in PubMed, ClinicalTrial.gov, and google electronic databases relevant to development, preclinical, clinical trials of nicotine, cocaine, methamphetamine, and opioid vaccines. Various new emerging vaccine development strategies for SUD were also identified through this search and discussed. A good number of vaccine candidates demonstrated promising results in preclinical and clinical phases and support the concept of developing a vaccine for SUD. However, there have been no ultimate success as yet, and there remain some challenges with a massive push to take more candidates to clinical trials for further evaluation to break the bottleneck.

Review of the Existing Translational Pharmacokinetics Modeling Approaches Specific to Monoclonal Antibodies (mAbs) to Support the First-In-Human (FIH) Dose Selection

The interest in therapeutic monoclonal antibodies (mAbs) has continuously growing in several diseases. However, their pharmacokinetics (PK) is complex due to their target-mediated drug disposition (TMDD) profiles which can induce a non-linear PK. This point is particularly challenging during the pre-clinical and translational development of a new mAb. This article reviews and describes the existing PK modeling approaches used to translate the mAbs PK from animal to human for intravenous (IV) and subcutaneous (SC) administration routes. Several approaches are presented, from the most empirical models to full physiologically based pharmacokinetic (PBPK) models, with a focus on the population PK methods (compartmental and minimal PBPK models). They include the translational approaches for the linear part of the PK and the TMDD mechanism of mAbs. The objective of this article is to provide an up-to-date overview and future perspectives of the translational PK approaches for mAbs during a model-informed drug development (MIDD), since the field of PK modeling has gained recently significant interest for guiding mAbs drug development.

Antibody-mediated protection against symptomatic COVID-19 can be achieved at low serum neutralizing titers

Multiple studies of vaccinated and convalescent cohorts have demonstrated that serum neutralizing antibody (nAb) titers correlate with protection against COVID-19. However, the induction of multiple layers of immunity following SARS-CoV-2 exposure has complicated the establishment of nAbs as a mechanistic correlate of protection (CoP) and hindered the definition of a protective nAb threshold. Here, we show that a half-life extended monoclonal antibody (adintrevimab) provides approximately 50% protection against symptomatic COVID-19 in SARS-CoV-2-naive adults at low serum nAb titers on the order of 1:30. Vaccine modeling supports a similar 50% protective nAb threshold, suggesting low levels of serum nAb can protect in both monoclonal and polyclonal settings. Extrapolation of adintrevimab pharmacokinetic data suggests that protection against susceptible variants could be maintained for approximately 3 years. The results provide a benchmark for the selection of next-generation vaccine candidates and support the use of broad, long-acting monoclonal antibodies as an alternative or supplement to vaccination in high-risk populations.

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.

Monoclonal Antibody Engineering and Design to Modulate FcRn Activities: A Comprehensive Review

Understanding the biological mechanisms underlying the pH-dependent nature of FcRn binding, as well as the various factors influencing the affinity to FcRn, was concurrent with the arrival of the first recombinant IgG monoclonal antibodies (mAbs) and IgG Fc-fusion proteins in clinical practice. IgG Fc–FcRn became a central subject of interest for the development of these drugs for the comfort of patients and good clinical responses. In this review, we describe (i) mAb mutations close to and outside the FcRn binding site, increasing the affinity for FcRn at acidic pH and leading to enhanced mAb half-life and biodistribution, and (ii) mAb mutations increasing the affinity for FcRn at acidic and neutral pH, blocking FcRn binding and resulting, in vivo, in endogenous IgG degradation. Mutations modifying FcRn binding are discussed in association with pH-dependent modulation of antigen binding and (iii) anti-FcRn mAbs, two of the latest innovations in anti-FcRn mAbs leading to endogenous IgG depletion. We discuss the pharmacological effects, the biological consequences, and advantages of targeting IgG–FcRn interactions and their application in human therapeutics.

Quantification of pharmacokinetic profiles of a recombinant canine PD-1 fusion protein by validated sandwich ELISA method

Tumors are becoming a serious threat to the quality of life of human and dogs. Studies have shown that tumors have caused more than half of the deaths in older dogs. Similar to human, dogs will develop various and highly heterogeneous tumors, but there are currently no viable therapies for them. In human, immunotherapy has been used widely and considered as an effective treatment for tumors by immune checkpoint targets, which are also expressed on canine tumors, suggesting that immunotherapy may be a potential treatment for canine tumors. In this work, we developed a sandwich ELISA method to detect the concentration of recombinant canine PD-1 fusion protein in canine serum and investigated pharmacokinetics in canines after intravenous infusion administration. After being validated, the ELISA method showed an excellent linear relationship in 25.00–3,200.00 ng/ml in serum, and the R² was more than 0.99 with four-parameter fitting. The precision and accuracy of intra-assay and inter-assay at the five different concentrations met the requirements of quantitative analysis. At the same time, no hook effect was observed at the concentration above ULOQ, and the stability was good under different predicted conditions with accuracy > 80%. The pharmacokinetic study in dogs has shown that the recombinant canine PD-1 fusion protein exhibited a typical biphasic PK profile after intravenous infusion administration, and the linear pharmacokinetic properties were observed between 1.00 and 12.00 mg/kg. Meanwhile, the T_1/2 after intravenous infusion administration with non-compartmental analysis was about 5.79 days.

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.

Comparative Efficacy and Rapidity of Action for Infliximab vs Ustekinumab in Biologic Naïve Crohn's Disease

BACKGROUND & AIMS

Comparative effectiveness has become increasingly important to help position therapies for inflammatory bowel disease. We compared the efficacy and rapidity of onset of action of infliximab vs ustekinumab induction therapy for moderate to severe biologic-naïve Crohn's disease (CD) using patient-level data from randomized controlled trials.

METHODS

This was a post hoc analysis of 2 large CD clinical trial programs that included data on 420 biologic-naïve CD patients. Differences in proportions of patients achieving week 6 clinical remission, clinical response, and normalization of calprotectin were compared. Multivariate logistic regression was used to adjust for confounders. Sensitivity analysis was conducted using propensity scores to create a cohort of matched participants with similar distribution of baseline covariates.

RESULTS

At week 6, a comparable number of patients achieved clinical remission with infliximab compared with patients treated with ustekinumab (44.9% vs 37.9%; adjusted odds ratio [aOR], 1.22; 95% CI, 0.79-1.89). Similarly, at week 6 the clinical response rates were not significantly different (58.4% infliximab vs 54.9% ustekinumab; aOR, 1.25; 95% CI, 0.82-1.90). No significant difference was observed between treatment groups for achieving a week 6 fecal calprotectin level less than 250 mcg/L in those with increased values at baseline (42.3% infliximab vs 34.7% ustekinumab; aOR, 1.34; 95% CI, 0.79-2.28). Similar results were seen for all analyses performed within the propensity matched cohort.

CONCLUSIONS

Based on this post hoc analysis, infliximab and ustekinumab appear to have similar efficacy and speed of onset in patients with CD who are biologic-naïve.

Bispecific Antibodies in Cancer Immunotherapy: A Novel Response to an Old Question

Immunotherapy has redefined the treatment of cancer patients and it is constantly generating new advances and approaches. Among the multiple options of immunotherapy, bispecific antibodies (bsAbs) represent a novel thoughtful approach. These drugs integrate the action of the immune system in a strategy to redirect the activation of innate and adaptive immunity toward specific antigens and specific tumor locations. Here we discussed some basic aspects of the design and function of bsAbs, their main challenges and the state-of-the-art of these molecules in the treatment of hematological and solid malignancies and future perspectives.

Mathematical Models to Characterize the Absorption, Distribution, Metabolism, and Excretion of Protein Therapeutics

Therapeutic proteins (TPs) have ranked among the most important and fastest-growing classes of drugs in the clinic, yet the development of successful TPs is often limited by unsatisfactory efficacy. Understanding pharmacokinetic (PK) characteristics of TPs is key to achieving sufficient and prolonged exposure at the site of action, which is a prerequisite for eliciting desired pharmacological effects. PK modeling represents a powerful tool to investigate factors governing in vivo disposition of TPs. In this mini-review, we discuss many state-of-the-art models that recapitulate critical processes in each of the absorption, distribution, metabolism/catabolism, and excretion pathways of TPs, which can be integrated into the physiologically-based pharmacokinetic framework. Additionally, we provide our perspectives on current opportunities and challenges for evolving the PK models to accelerate the discovery and development of safe and efficacious TPs. SIGNIFICANCE STATEMENT: This minireview provides an overview of mechanistic pharmacokinetic (PK) models developed to characterize absorption, distribution, metabolism, and elimination (ADME) properties of therapeutic proteins (TPs), which can support model-informed discovery and development of TPs. As the next-generation of TPs with diverse physicochemical properties and mechanism-of-action are being developed rapidly, there is an urgent need to better understand the determinants for the ADME of TPs and evolve existing platform PK models to facilitate successful bench-to-bedside translation of these promising drug molecules.

Camelid Single-Domain Antibodies: Promises and Challenges as Lifesaving Treatments

Since the discovery of camelid heavy-chain antibodies in 1993, there has been tremendous excitement for these antibody domains (VHHs/sdAbs/nanobodies) as research tools, diagnostics, and therapeutics. Commercially, several patents were granted to pioneering research groups in Belgium and the Netherlands between 1996–2001. Ablynx was established in 2001 with the aim of exploring the therapeutic applications and development of nanobody drugs. Extensive efforts over two decades at Ablynx led to the first approved nanobody drug, caplacizumab (Cablivi) by the EMA and FDA (2018–2019) for the treatment of rare blood clotting disorders in adults with acquired thrombotic thrombocytopenic purpura (TPP). The relatively long development time between camelid sdAb discovery and their entry into the market reflects the novelty of the approach, together with intellectual property restrictions and freedom-to-operate issues. The approval of the first sdAb drug, together with the expiration of key patents, may open a new horizon for the emergence of camelid sdAbs as mainstream biotherapeutics in the years to come. It remains to be seen if nanobody-based drugs will be cheaper than traditional antibodies. In this review, I provide critical perspectives on camelid sdAbs and present the promises and challenges to their widespread adoption as diagnostic and therapeutic agents.

Recent Advances in Translational Pharmacokinetics and Pharmacodynamics Prediction of Therapeutic Antibodies Using Modeling and Simulation

Therapeutic monoclonal antibodies (mAbs) have been a promising therapeutic approach for several diseases and a wide variety of mAbs are being evaluated in clinical trials. To accelerate clinical development and improve the probability of success, pharmacokinetics and pharmacodynamics (PKPD) in humans must be predicted before clinical trials can begin. Traditionally, empirical-approach-based PKPD prediction has been applied for a long time. Recently, modeling and simulation (M&S) methods have also become valuable for quantitatively predicting PKPD in humans. Although several models (e.g., the compartment model, Michaelis–Menten model, target-mediated drug disposition model, and physiologically based pharmacokinetic model) have been established and used to predict the PKPD of mAbs in humans, more complex mechanistic models, such as the quantitative systemics pharmacology model, have been recently developed. This review summarizes the recent advances and future direction of M&S-based approaches to the quantitative prediction of human PKPD for mAbs.