Preclinical Models Used for Immunogenicity Prediction of Therapeutic Proteins

Enhancing cellular immunotherapies in cancer by engineering selective therapeutic resistance

Adoptive cell therapies engineered to express chimeric antigen receptors (CARs) or transgenic T cell receptors (TCRs) to recognize and eliminate cancer cells have emerged as a promising approach for achieving long-term remissions in patients with cancer. To be effective, the engineered cells must persist at therapeutically relevant levels while avoiding off-tumour toxicities, which has been challenging to realize outside of B cell and plasma cell malignancies. This Review discusses concepts to enhance the efficacy, safety and accessibility of cellular immunotherapies by endowing cells with selective resistance to small-molecule drugs or antibody-based therapies to facilitate combination therapies with substances that would otherwise interfere with the functionality of the effector cells. We further explore the utility of engineering healthy haematopoietic stem cells to confer resistance to antigen-directed immunotherapies and small-molecule targeted therapies to expand the therapeutic index of said targeted anticancer agents as well as to facilitate in vivo selection of gene-edited haematopoietic stem cells for non-malignant applications. Lastly, we discuss approaches to evade immune rejection, which may be required in the setting of allogeneic cell therapies. Increasing confidence in the tools and outcomes of genetically modified cell therapy now paves the way for rational combinations that will open new therapeutic horizons.

Biological Functions of Macromolecular Protein Hydrogels in Constructing Osteogenic Microenvironment

Irreversible bone defects resulting from trauma, infection, and degenerative illnesses have emerged as a significant health concern. Structurally and functionally controllable hydrogels made by bone tissue engineering (BTE) have become promising biomaterials. Natural proteins are able to establish connections with autologous proteins through unique biologically active regions. Hydrogels based on proteins can simulate the bone microenvironment and regulate the biological behavior of stem cells in the tissue niche, making them candidates for research related to bone regeneration. This article reviews the biological functions of various natural macromolecular proteins (such as collagen, gelatin, fibrin, and silk fibroin) and highlights their special advantages as hydrogels. Then the latest research trends on cross-linking modified macromolecular protein hydrogels with improved mechanical properties and composite hydrogels loaded with exogenous micromolecular proteins have been discussed. Finally, the applications of protein hydrogels, such as 3D printed hydrogels, microspheres, and injectable hydrogels, were introduced, aiming to provide a reference for the repair of clinical bone defects.

Living in LALA land? Forty years of attenuating Fc effector functions

The Fc region of antibodies is vital for most of their physiological functions, many of which are engaged through binding to a range of Fc receptors. However, these same interactions are not always helpful or wanted when therapeutic antibodies are directed against self-antigens, and can sometimes cause catastrophic adverse reactions. Over the past 40 years, there have been intensive efforts to "silence" unwanted binding to Fc-gamma receptors, resulting in at least 45 different variants which have entered clinical trials. One of the best known is "LALA" (L234A/L235A). However, neither this, nor most of the other variants in clinical use are completely silenced, and in addition, the biophysical properties of many of them are compromised. I review the development of different variants to see what we can learn from their biological properties and use in the clinic. With the rise of powerful new uses of antibody therapy such as bispecific T-cell engagers, antibody-drug conjugates, and checkpoint inhibitors, it is increasingly important to optimize the Fc region as well as the antibody binding site in order to achieve the best combination of safety and efficacy.

Patient-Centric Quality Standards

To ensure the quality, safety and efficacy of medicinal products, it is necessary to develop and execute appropriate manufacturing process and product control strategies. Traditionally, product control strategies have focused on testing known quality attributes with limits derived from levels administered in preclinical and clinical studies with an associated statistical analysis to account for variability. However, not all quality attributes have impact to the patient and those with the potential to impact safety and efficacy may not be significant when dosed at patient-centric levels. Therefore, achieving patient-centricity is understanding patient relevance, which is defined as the level of impact that a quality attribute could have on safety and efficacy within the potential exposure range. A patient-centric quality standard (PCQS) is therefore a set of patient relevant attributes and their associated acceptance ranges to which a drug product should conform within the expected patient exposure range. This manuscript describes historical perspectives details the way to create and leverage a PCQS in a variety of pharmaceutical product modalities.

A mechanistic marker-based screening tool to predict clinical immunogenicity of biologics

BACKGROUND

The efficacy and safety of therapeutic proteins are undermined by immunogenicity driven by anti-drug antibodies. Immunogenicity risk assessment is critically necessary during drug development, but current methods lack predictive power and mechanistic insight into antigen uptake and processing leading to immune response. A key mechanistic step in T-cell-dependent immune responses is the migration of mature dendritic cells to T-cell areas of lymphoid compartments, and this phenomenon is most pronounced in the immune response toward subcutaneously delivered proteins.

METHODS

The migratory potential of monocyte-derived dendritic cells is proposed to be a mechanistic marker for immunogenicity screening. Following exposure to therapeutic protein in vitro, dendritic cells are analyzed for changes in activation markers (CD40 and IL-12) in combination with levels of the chemokine receptor CXCR4 to represent migratory potential. Then a transwell assay captures the intensity of dendritic cell migration in the presence of a gradient of therapeutic protein and chemokine ligands.

RESULTS

Here, we show that an increased ability of the therapeutic protein to induce dendritic cell migration along a gradient of chemokine CCL21 and CXCL12 predicts higher immunogenic potential. Expression of the chemokine receptor CXCR4 on human monocyte-derived dendritic cells, in combination with activation markers CD40 and IL-12, strongly correlates with clinical anti-drug antibody incidence.

CONCLUSIONS

Mechanistic understanding of processes driving immunogenicity led to the development of a predictive tool for immunogenicity risk assessment of therapeutic proteins. These predictive markers could be adapted for immunogenicity screening of other biological modalities.

A humanized minipig model for the toxicological testing of therapeutic recombinant antibodies

The safety of most human recombinant proteins can be evaluated in transgenic mice tolerant to specific human proteins. However, owing to insufficient genetic diversity and to fundamental differences in immune mechanisms, small-animal models of human diseases are often unsuitable for immunogenicity testing and for predicting adverse outcomes in human patients. Most human therapeutic antibodies trigger xenogeneic responses in wild-type animals and thus rapid clearance of the drugs, which makes in vivo toxicological testing of human antibodies challenging. Here we report the generation of Göttingen minipigs carrying a mini-repertoire of human genes for the immunoglobulin heavy chains γ1 and γ4 and the immunoglobulin light chain κ. In line with observations in human patients, the genetically modified minipigs tolerated the clinically non-immunogenic IgG1κ-isotype monoclonal antibodies daratumumab and bevacizumab, and elicited antibodies against the checkpoint inhibitor atezolizumab and the engineered interleukin cergutuzumab amunaleukin. The humanized minipigs can facilitate the safety and efficacy testing of therapeutic antibodies.

Fc-engineered antibodies with immune effector functions completely abolished

Elimination of the binding of immunoglobulin Fc to Fc gamma receptors (FcγR) is highly desirable for the avoidance of unwanted inflammatory responses to therapeutic antibodies and fusion proteins. Many different approaches have been described in the literature but none of them completely eliminates binding to all of the Fcγ receptors. Here we describe a set of novel variants having specific amino acid substitutions in the Fc region at L234 and L235 combined with the substitution G236R. They show no detectable binding to Fcγ receptors or to C1q, are inactive in functional cell-based assays and do not elicit inflammatory cytokine responses. Meanwhile, binding to FcRn, manufacturability, stability and potential for immunogenicity are unaffected. These variants have the potential to improve the safety and efficacy of therapeutic antibodies and Fc fusion proteins.

Managing the Impact of Immunogenicity in an Era of Immunotherapy: From Bench to Bedside

Biotherapeutics have revolutionized our ability to treat life-threatening diseases. Despite clinical success, the use of biotherapeutics has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs). The multifactorial nature of immunogenicity has prevented a standardized approach for assessing this and each of the assessment methods developed so far does not exhibit high enough reliability to be used alone, due to limited predictiveness. This prompted the Roche Pharma Research and Early Development (pRED) Immunogenicity Working Group to establish an internal preclinical immunogenicity toolbox of in vitro/in vivo approaches and accompanying guidelines for a harmonized assessment and management of immunogenicity in early development. In this article, the complex factors influencing immunogenicity and their associated clinical ramifications are discussed to highlight the importance of an end-to-end approach conducted from lead optimization to clinical candidate selection. We then examine the impact of the resulting lead candidate categorization on the design and implementation of a multi-tiered ADA/immunogenicity assay strategy prior to phase I (entry into human) through early clinical development. Ultimately, the Immunogenicity Toolbox ensures that Roche pRED teams are equipped to address immunogenicity in a standardized manner, paving the way for lifesaving products with improved safety and efficacy.

The Peripheral Immune Landscape of Breast Cancer: Clinical Findings and In Vitro Models for Biomarker Discovery

Breast cancer is the deadliest female malignancy worldwide and, while much is known about phenotype and function of infiltrating immune cells, the same attention has not been paid to the peripheral immune compartment of breast cancer patients. To obtain faster, cheaper, and more precise monitoring of patients' status, it is crucial to define and analyze circulating immune profiles. This review compiles and summarizes the disperse knowledge on the peripheral immune profile of breast cancer patients, how it departs from healthy individuals and how it changes with disease progression. We propose this data to be used as a starting point for validation of clinically relevant biomarkers of disease progression and therapy response, which warrants more thorough investigation in patient cohorts of specific breast cancer subtypes. Relevant clinical findings may also be explored experimentally using advanced 3D cellular models of human cancer-immune system interactions, which are under intensive development. We review the latest findings and discuss the strengths and limitations of such models, as well as the future perspectives. Together, the scientific advancement of peripheral biomarker discovery and cancer-immune crosstalk in breast cancer will be instrumental to uncover molecular mechanisms and putative biomarkers and drug targets in an all-human setting.

Therapeutic peptides for the treatment of cystic fibrosis: Challenges and perspectives

Cystic fibrosis (CF) is the most common amongst rare genetic diseases, affecting more than 70.000 people worldwide. CF is characterized by a dysfunctional chloride channel, termed cystic fibrosis conductance regulator (CFTR), which leads to the production of a thick and viscous mucus layer that clogs the lungs of CF patients and traps pathogens, leading to chronic infections and inflammation and, ultimately, lung damage. In recent years, the use of peptides for the treatment of respiratory diseases, including CF, has gained growing interest. Therapeutic peptides for CF include antimicrobial peptides, inhibitors of proteases, and modulators of ion channels, among others. Peptides display unique features that make them appealing candidates for clinical translation, like specificity of action, high efficacy, and low toxicity. Nevertheless, the intrinsic properties of peptides, together with the need of delivering these compounds locally, e.g. by inhalation, raise a number of concerns in the development of peptide therapeutics for CF lung disease. In this review, we discuss the challenges related to the use of peptides for the treatment of CF lung disease through inhalation, which include retention within mucus, proteolysis, immunogenicity and aggregation. Strategies for overcoming major shortcomings of peptide therapeutics will be presented, together with recent developments in peptide design and optimization, including computational analysis and high-throughput screening.

Particle Detection and Characterization for Biopharmaceutical Applications: Current Principles of Established and Alternative Techniques

Detection and characterization of particles in the visible and subvisible size range is critical in many fields of industrial research. Commercial particle analysis systems have proliferated over the last decade. Despite that growth, most systems continue to be based on well-established principles, and only a handful of new approaches have emerged. Identifying the right particle-analysis approach remains a challenge in research and development. The choice depends on each individual application, the sample, and the information the operator needs to obtain. In biopharmaceutical applications, particle analysis decisions must take product safety, product quality, and regulatory requirements into account. Biopharmaceutical process samples and formulations are dynamic, polydisperse, and very susceptible to chemical and physical degradation: improperly handled product can degrade, becoming inactive or in specific cases immunogenic. This article reviews current methods for detecting, analyzing, and characterizing particles in the biopharmaceutical context. The first part of our article represents an overview about current particle detection and characterization principles, which are in part the base of the emerging techniques. It is very important to understand the measuring principle, in order to be adequately able to judge the outcome of the used assay. Typical principles used in all application fields, including particle–light interactions, the Coulter principle, suspended microchannel resonators, sedimentation processes, and further separation principles, are summarized to illustrate their potentials and limitations considering the investigated samples. In the second part, we describe potential technical approaches for biopharmaceutical particle analysis as some promising techniques, such as nanoparticle tracking analysis (NTA), micro flow imaging (MFI), tunable resistive pulse sensing (TRPS), flow cytometry, and the space- and time-resolved extinction profile (STEP^®) technology.

Safety biomarkers for development of vaccines and biologics: Report from the safety biomarkers symposium held on November 28-29, 2017, Marcy l'Etoile, France

Vaccines prevent infectious diseases, but vaccination is not without risk and adverse events are reported although they are more commonly reported for biologicals than for vaccines. Vaccines and biologicals must undergo vigorous assessment before and after licensure to minimise safety concerns. Potential safety concerns should be identified as early as possible during the development for vaccines and biologicals to minimize investment risk. State-of-the art tools and methods to identify safety concerns and biomarkers that are predictive of clinical outcomes are indispensable. For vaccines and adjuvant formulations, systems biology approaches, supported by single-cell microfluidics applied to translational studies between preclinical and clinical studies, could improve reactogenicity and safety predictions. Next-generation animal models for clinical assessment of injection-site reactions with greater relevance for target human population and criteria to define the level of acceptability of local reactogenicity at vaccine injection sites in pre-clinical animal species should be assessed. Advanced in silico machine-learning-based analytics, species-specific cell or tissue expression, receptor occupancy and kinetics and cell-based assays for functional activity are needed to improve pre-clinical safety assessment of biologicals. The in vitro MIMIC® system could be used to compliment preclinical and clinical studies for assessing immune-toxicity, immunogenicity, immuno-inflammatory and mode of action of biologicals and vaccines. Sanofi Pasteur brought together leading experts in this field to review the state-of-the-art at a unique 'Safety Biomarkers Symposium' on 28-29 November 2017. Here we summarise the proceedings of this symposium. This unique scientific meeting confirmed the importance for institutions and industrial organizations to collaborate to develop tools and methods needed for predicting reactogenicity and immune-inflammatory reactions to vaccines and biologicals, and to develop more accuracy, reliability safety biomarkers, to inform decisions on the attrition or advancement of vaccines and biologicals.

Driving CARs with alternative navigation tools - the potential of engineered binding scaffolds

T cells that are genetically engineered to express chimeric antigen receptors (CAR T cells) have shown impressive clinical efficacy against B‐cell malignancies. In contrast to these highly potent CD19‐targeting CAR T cells, many of those directed against other tumor entities and antigens currently suffer from several limitations. For example, it has been demonstrated that many scFvs used as antigen‐binding domains in CARs show some degree of oligomerization, which leads to tonic signaling, T cell exhaustion, and poor performance in vivo. Therefore, in many cases alternatives to scFvs would be beneficial. Fortunately, due to the development of powerful protein engineering technologies, also non‐immunoglobulin‐based scaffolds can be engineered to specifically recognize antigens, thus eliminating the historical dependence on antibody‐based binding domains. Here, we discuss the advantages and disadvantages of such engineered binding scaffolds, in particular with respect to their application in CARs. We review recent studies, collectively showing that there is no functional or biochemical aspect that necessitates the use of scFvs in CARs. Instead, antigen recognition can also be mediated efficiently by engineered binding scaffolds, as well as natural ligands or receptors fused to the CAR backbone. Finally, we critically discuss the risk of immunogenicity and show that the extent of nonhuman amino acid stretches in engineered scaffolds—even in those based on nonhuman proteins—is more similar to humanized scFvs than might be anticipated. Together, we expect that engineered binding scaffolds and natural ligands and receptors will be increasingly used for the design of CAR T cells.

Formation and Glomerular Deposition of Immune Complexes in Mice Administered Human Antibodies: Evaluation of Dose, Frequency, and Biomarkers

Administration of human protein-based drugs to animals often leads to formation of antidrug antibodies (ADAs) that may form circulating immune complexes (CICs) with the dosed protein. Circulating immune complexes can activate and bind complement (cCICs), and if large amount of CICs or cCICs is formed, the clearance mechanism potentially becomes saturated, which can lead to immune complex (IC) deposition and inflammation. To obtain a better understanding of the underlying factors, including the relationship between different dose regimes on IC formation and deposition and identification of possible biomarkers of IC deposition and IC-related pathological changes in kidneys, BALB/c and C57BL/6J mice were administered with human anti-tumor necrosis factor α (aTNFα, adalimumab) or a humanized anti-TNP (aTNP) antibody for 13 weeks. Particularly, ADA, CIC, cCIC formation, IC deposition, and glomerulonephritis were observed in C57BL/6J administered with aTNFα, whereas the immunologic response was minor in BALB/c mice administered with aTNFα and in BALB/c and C57BL/6J mice administered aTNP. Changing dose levels or increasing dosing frequency of aTNFα on top of an already-established CIC and cCIC response did not lead to substantial changes in CIC, cCIC formation, or IC deposition. Finally, no association between the presence of CICs or cCIC in plasma and glomerular IC deposition and/or glomerulonephritis was observed.

Miniproteins as a Powerful Modality in Drug Development

Miniproteins are a diverse group of protein scaffolds characterized by small (1-10 kDa) size, stability, and versatility in drug-like roles. Coming largely from native sources, they have been widely adopted into drug development pipelines. While their structures and capabilities are diverse, the approaches to their utilization share more similarities with each other than with more widely used modalities (e.g., antibodies or small molecules). In this review, we highlight recent advances in miniprotein-based approaches to otherwise poorly addressed clinical needs, including structure-based and functional characterization. We also summarize their unique screening strategies and pharmacology considerations. Through a greater understanding of the unique properties that make them attractive for drug design, miniproteins can be effectively utilized against targets that are intractable by other approaches.

Shifting Paradigms Revisited: Biotechnology and the Pharmaceutical Sciences

In 2003, Crommelin et al. published an article titled: "Shifting paradigms: biopharmaceuticals versus low molecular weight drugs" (https://doi.org/10.1016/S0378-5173(03)00376-4). In the present commentary, 16 years later, we discuss pharmaceutically relevant aspects of the evolution of biologics since then. First, we discuss the increasing repertoire of biologics, in particular, the rapidly growing monoclonal antibody family and the advent of advanced therapy medicinal products. Next, we discuss trends in formulation and characterization as well as summarize our current insights into immunogenicity of biologics. We spend a separate section on new product(ion) paradigms for biologics, such as cell-free production systems, production of advanced therapy medicinal products, and downscaled production approaches. Furthermore, we share our views on issues related to reaching the patient, including routes and techniques of administration, alternative development models for affordable biologics, biosimilars, and handling of biologics. In the concluding section, we outline outstanding issues and make some suggestions for resolving those.

Evaluation of a 3D Human Artificial Lymph Node as Test Model for the Assessment of Immunogenicity of Protein Aggregates

The immunogenicity of protein aggregates has been investigated in numerous studies. Nevertheless, it is still unknown which kind of protein aggregates enhance immunogenicity the most. The ability of the currently used in vitro and in vivo systems regarding their predictability of immunogenicity in humans is often questionable, and results are partially contradictive. In this study, we used a 2D in vitro assay and a complex 3D human artificial lymph node model to predict the immunogenicity of protein aggregates of bevacizumab and adalimumab. The monoclonal antibodies were exposed to different stress conditions such as light, heat, and mechanical stress to trigger the formation of protein aggregates and particles, and samples were analyzed thoroughly. Cells and culture supernatants were harvested and analyzed for dendritic cell marker and cytokines. Our study in the artificial lymph node model revealed that bevacizumab after exposure to heat triggered a TH1- and proinflammatory immune response, whereas no trend of immune responses was seen for adalimumab after exposure to different stress conditions. The human artificial lymph node model represents a new test model for testing the immunogenicity of protein aggregates combining the relevance of a 3D human system with the rather easy handling of an in vitro setup.

Test models for the evaluation of immunogenicity of protein aggregates

Protein aggregates have been discussed for a long time as a potential risk factor for immunogenicity in patients. Meanwhile, many research groups have investigated the immunogenicity of differently produced aggregates using in vitro or in vivo models. Despite all knowledge gained in these studies still little is known about the mechanisms of immunogenicity and the kind of protein aggregates bearing the greatest risk for immunogenicity. The choice of a suitable test model regarding the predictability of immunogenicity of protein aggregates in humans plays a major role and influences results and conclusions substantially. In this review we will provide an overview of the test models recently used for the evaluation of immunogenicity of protein aggregates; we will discuss advantages and drawbacks regarding their usability and predictive power for immunogenicity in humans.

Risk-Based Comparability Assessment for Monoclonal Antibodies During Drug Development: A Clinical Pharmacology Perspective

Due to complexities in the structure, function, and manufacturing process of antibody-based therapeutic proteins, comparability assessment for supporting manufacturing changes can sometimes be a challenging task. Regulatory guidance recommends a hierarchical risk-based approach, starting with Chemistry, Manufacturing, and Controls (CMC) analytical characterizations, followed by non-clinical and/or clinical studies to ensure that any potential changes in quality attributes have no adverse impact on efficacy and safety of the product. This review focuses on the changes in quality attributes which may potentially affect the pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of a monoclonal antibody (mAb) product, and provides general guidelines in designing non-clinical and clinical PK/PD studies to help support comparability assessments. A decision tree for comparability assessment is proposed depending on the nature of the changes in quality attributes, the potential impact of such changes, and the timing of the manufacturing change relative to the development process. Ideally, the optimization of manufacturing process should take place in the early stage of drug development (i.e., preclinical to phase 2a) as more stringent comparability criteria would have to be met if manufacturing changes occur in the late stage of drug development (i.e., phase 2b and after), and consequently, major changes in manufacturing process should be avoided during confirmatory phase 3 studies and post-approval of drug products.

Aggregates of IVIG or Avastin, but not HSA, modify the response to model innate immune response modulating impurities

Therapeutic proteins can induce immune responses that affect their safety and efficacy. Product aggregates and innate immune response modulating impurities (IIRMI) are risk factors of product immunogenicity. In this study, we use Intravenous Immunoglobulin (IVIG), Avastin, and Human Serum Albumin (HSA) to explore whether increased aggregates activate innate immune cells or modify the response to IIRMI. We show that increased aggregates (shaken or stirred) in IVIG and Avastin, but not HSA, induced activation of MAPKs (pp38, pERK and pJNK) and transcription of immune-related genes including IL8, IL6, IL1β, CSF1, CCL2, CCL7, CCL3, CCL24, CXCL2, IRAK1, EGR2, CEBPβ, PPARg and TNFSF15 in human PBMC. The immunomodulatory effect was primarily mediated by FcγR, but not by TLR. Interestingly, increased aggregates in IVIG or Avastin magnified innate immune responses to TLR2/4 agonists, but diminished responses to TLR3/9 agonists. This study shows that IIRMI and aggregates can modify the activity of immune cells potentially modifying the milieu where the products are delivered highlighting the complex interplay of different impurities on product immunogenicity risk. Further, we show that aggregates could modify the sensitivity of PBMC-based assays designed to detect IIRMI. Understanding and managing immunogenicity risk is a critical component of product development and regulation.

Submicron Size Particles of a Murine Monoclonal Antibody Are More Immunogenic Than Soluble Oligomers or Micron Size Particles Upon Subcutaneous Administration in Mice

Protein aggregates are one of the several risk factors for undesired immunogenicity of biopharmaceuticals. However, it remains unclear which features determine whether aggregates will trigger an unwanted immune response. The aim of this study was to determine the effect of aggregates' size on their relative immunogenicity. A monoclonal murine IgG1 was stressed by exposure to low pH and elevated temperature followed by stirring to obtain aggregates widely differing in size. Aggregate fractions enriched in soluble oligomers, submicron size particles and micron size particles were isolated via centrifugation or size-exclusion chromatography and characterized physicochemically. The secondary and tertiary structures of aggregates were altered in a similar way for all the fractions, while no substantial chemical degradation was observed. Development of anti-drug antibodies was measured after subcutaneous administration of each enriched fraction to BALB/c mice. Among all tested fractions, the most immunogenic was the one highly enriched in submicron size particles (∼100-1000 nm). Fractions composed of micron size (>1-100 μm) particles or soluble oligomers (<100 nm) were not immunogenic under the dosing regimen studied in this work. These results show that aggregate size is an important factor for protein immunogenicity.

Enrichment of endogenous fractalkine and anti-inflammatory cells via aptamer-functionalized hydrogels

Early recruitment of non-classical monocytes and their macrophage derivatives is associated with augmented tissue repair and improved integration of biomaterial constructs. A promising therapeutic approach to recruit these subpopulations is by elevating local concentrations of chemoattractants such as fractalkine (FKN, CX3CL1). However, delivering recombinant or purified proteins is not ideal due to their short half-lives, suboptimal efficacy, immunogenic potential, batch variabilities, and cost. Here we report an approach to enrich endogenous FKN, obviating the need for delivery of exogenous proteins. In this study, modified FKN-binding-aptamers are integrated with poly(ethylene glycol) diacrylate to form aptamer-functionalized hydrogels ("aptagels") that localize, dramatically enrich and passively release FKN in vitro for at least one week. Implantation in a mouse model of excisional skin injury demonstrates that aptagels enrich endogenous FKN and stimulate significant local increases in Ly6C^loCX3CR1^hi non-classical monocytes and CD206⁺ M2-like macrophages. The results demonstrate that orchestrators of inflammation can be manipulated without delivery of foreign proteins or cells and FKN-aptamer functionalized biomaterials may be a promising approach to recruit anti-inflammatory subpopulations to sites of injury. Aptagels are readily synthesized, highly customizable and could combine different aptamers to treat complex diseases in which regulation or enrichment of multiple proteins may be therapeutic.

Computational methods in preformulation study for pharmaceutical solid dosage forms of therapeutic proteins

Design and delivery of protein-based biopharmaceuticals needs detailed planning and strict monitoring of intermediate processing steps, storage conditions and container-closure system to ensure a stable, elegant and biopharmaceutically acceptable dosage form. Selection of manufacturing process variables and conditions along with packaging specifications can be achieved through properly designed preformulation study protocol for the formulation. Thermodynamic stability and biological activity of therapeutic proteins depend on folding–unfolding and three-dimensional packing dynamics of amino acid network in the protein molecule. Lack of favourable environment may cause protein aggregation with loss in activity and even fatal immunological reaction. Although lyophilization can enhance the stability of protein-based formulations in the solid state, it can induce protein unfolding leading to thermodynamic instability. Formulation stabilizers such as preservatives can also result in aggregation of therapeutic proteins. Modern instrumental techniques in conjunction with computational tools enable rapid and accurate prediction of amino acid sequence, thermodynamic parameters associated with protein folding and detection of aggregation “hot-spots.” Globular proteins pose a challenge during investigations on their aggregation propensity. Biobetter therapeutic monoclonal antibodies with enhanced stability, solubility and reduced immunogenic potential can be designed through mutation of aggregation-prone zones. The objective of the present review article is to focus on the various analytical methods and computational approaches used in the study of thermodynamic stability and aggregation tendency of therapeutic proteins, with an aim to develop optimal and marketable formulation. Knowledge of protein dynamics through application of computational tools will provide the essential inputs and relevant information for successful and meaningful completion of preformulation studies on solid dosage forms of therapeutic proteins.

Extensive preclinical evaluation of an infliximab biosimilar candidate

Infliximab is therapeutic monoclonal antibody (mAb) against TNF-α employed in the treatment of immunoinflammatory diseases. The development of biosimilar mAbs is a global strategy to increase drug accessibility and reduce therapy-associated costs. Herein we compared key physicochemical characteristics and biological activities produced by infliximab and infliximab-Probiomed in order to identify functionally relevant differences between the mAbs. Binding of infliximab-Probiomed to TNF-α was specific and had kinetics comparable to that of the reference product. Both mAbs had highly similar neutralizing efficacy in HUVEC cell cultures stimulated with TNF-α. In vitro induction of CDC and ADCC were also similar between the evaluated products. In vivo comparability was assessed using a transgenic mouse model of arthritis that expresses human TNF-α in a 13-week multiple-administration study. Infliximab and infliximab-Probiomed showed comparable efficacy, safety, and pharmacokinetic profiles. Our results indicate that infliximab-Probiomed has highly similar activities to infliximab in preclinical models, warranting a clinical evaluation of its biosimilarity.

Unraveling the Effect of Immunogenicity on the PK/PD, Efficacy, and Safety of Therapeutic Proteins

Biologics have emerged as a powerful and diverse class of molecular and cell-based therapies that are capable of replacing enzymes, editing genomes, targeting tumors, and more. As this complex array of tools arises a distinct set of challenges is rarely encountered in the development of small molecule therapies. Biotherapeutics tend to be big, bulky, polar molecules comprised of protein and/or nucleic acids. Compared to their small molecule counterparts, they are fragile, labile, and heterogeneous. Their biodistribution is often limited by hydrophobic barriers which often restrict their administration to either intravenous or subcutaneous entry routes. Additionally, their potential for immunogenicity has proven to be a challenge to developing safe and reliably efficacious drugs. Our discussion will emphasize immunogenicity in the context of therapeutic proteins, a well-known class of biologics. We set out to describe what is known and unknown about the mechanisms underlying the interplay between antigenicity and immune response and their effect on the safety, efficacy, pharmacokinetics, and pharmacodynamics of these therapeutic agents.

Design and engineering of deimmunized biotherapeutics

Therapeutic proteins are powerful next-generation drugs able to effectively treat diverse and devastating diseases, but the development and use of biotherapeutics entails unique challenges and risks. In particular, protein drugs are subject to immune surveillance in the human body, and ensuing antidrug immune responses can cause a wide range of problems including altered pharmacokinetics, loss of efficacy, and even life-threating complications. Here we review recent progress in technologies for engineering deimmunized biotherapeutics, placing particular emphasis on deletion of immunogenic antibody and T cell epitopes via experimentally or computationally guided mutagenesis.

Mouse Models for Assessing Protein Immunogenicity: Lessons and Challenges

The success of clinical and commercial therapeutic proteins is rapidly increasing, but their potential immunogenicity is an ongoing concern. Most of the studies that have been conducted over the past few years to examine the importance of various product-related attributes (in particular several types of aggregates and particles) and treatment regimen (such as dose, dosing schedule, and route of administration) in the development of unwanted immune responses have utilized one of a variety of mouse models. In this review, we discuss the utility and drawbacks of different mouse models that have been used for this purpose. Moreover, we summarize the lessons these models have taught us and some of the challenges they present. Finally, we provide recommendations for future research utilizing mouse models to improve our understanding of critical factors that may contribute to protein immunogenicity.

The Role of Aggregates of Therapeutic Protein Products in Immunogenicity: An Evaluation by Mathematical Modeling

Therapeutic protein products (TPP) have been widely used to treat a variety of human diseases, including cancer, hemophilia, and autoimmune diseases. However, TPP can induce unwanted immune responses that can impact both drug efficacy and patient safety. The presence of aggregates is of particular concern as they have been implicated in inducing both T cell-independent and T cell-dependent immune responses. We used mathematical modeling to evaluate several mechanisms through which aggregates of TPP could contribute to the development of immunogenicity. Modeling interactions between aggregates and B cell receptors demonstrated that aggregates are unlikely to induce T cell-independent immune responses by cross-linking B cell receptors because the amount of signal transducing complex that can form under physiologically relevant conditions is limited. We systematically evaluate the role of aggregates in inducing T cell-dependent immune responses using a recently developed multiscale mechanistic mathematical model. Our analysis indicates that aggregates could contribute to T cell-dependent immune response by inducing high affinity epitopes which may not be present in the nonaggregated TPP and/or by enhancing danger signals to break tolerance. In summary, our computational analysis is suggestive of novel insights into the mechanisms underlying aggregate-induced immunogenicity, which could be used to develop mitigation strategies.

Engineering less immunogenic and antigenic FVIII proteins

The development of neutralizing antibodies against blood coagulation factor VIII (FVIII), referred to clinically as "inhibitors", is the most challenging and deleterious adverse event to occur following intravenous infusions of FVIII to treat hemophilia A. Inhibitors occlude FVIII surfaces that must bind to activated phospholipid membranes, the serine proteinase factor IXa, and other components of the 'intrinsic tenase complex' in order to carry out its important role in accelerating blood coagulation. Inhibitors develop in up to one of every three patients, yet remarkably, a substantial majority of severe hemophilia A patients, who circulate no detectable FVIII antigen or activity, acquire immune tolerance to FVIII during initial infusions or else after intensive FVIII therapy to overcome their inhibitor. The design of less immunogenic FVIII proteins through identification and modification ("de-immunization") of immunodominant T-cell epitopes is an important goal. For patients who develop persistent inhibitors, modification of B-cell epitopes through substitution of surface-exposed amino acid side chains and/or attachment of bulky moieties to interfere with FVIII attachment to antibodies and memory B cells is a promising approach. Both experimental and computational methods are being employed to achieve these goals. Future therapies for hemophilia A, as well as other monogenic deficiency diseases, are likely to involve administration of less immunogenic proteins in conjunction with other novel immunotherapies to promote a regulatory cellular environment promoting durable immune tolerance.

Changes in the amino acid sequence of the recombinant human factor VIIa analog, vatreptacog alfa, are associated with clinical immunogenicity

BACKGROUND

Vatreptacog alfa, a recombinant human factor VIIa (rFVIIa) analog developed to improve the treatment of bleeds in hemophilia patients with inhibitors, differs from native FVIIa by three amino acid substitutions. In a randomized, double-blind, crossover, confirmatory phase III trial (adept(™) 2), 8/72 (11%) hemophilia A or B patients with inhibitors treated for acute bleeds developed anti-drug antibodies (ADAs) to vatreptacog alfa.

OBJECTIVES

To characterize the formation of anti-vatreptacog alfa ADAs in hemophilia patients with inhibitors.

METHODS/PATIENTS

This was a post hoc analysis of adept(™) 2. Immunoglobulin isotype determination, specificity analysis of rFVIIa cross-reactive antibodies, epitope mapping of rFVIIa single mutant analogs and pharmacokinetic (PK) profiling were performed to characterize the ADAs.

RESULTS

Immunoglobulin isotyping indicated that the ADAs were of the immunoglobulin G subtype. In epitope mapping, none of the rFVIIa single mutant analogs (V158D, E296V or M298Q) contained the complete antibody epitope, confirming that the antibodies were specific for vatreptacog alfa. In two patients, for whom PK profiling was performed both before and after the development of ADAs, vatreptacog alfa showed a prolonged elimination phase following ADA development. During the follow-up evaluation, the rFVIIa cross-reactivity disappeared after the last vatreptacog alfa exposure, despite continued exposure to rFVIIa as part of standard care.

CONCLUSIONS

Results from the vatreptacog alfa phase III trial demonstrate that the specific changes made, albeit relatively small, to the FVIIa molecule alter its clinical immunogenicity.

Pharmacokinetic and pharmacodynamic considerations for the next generation protein therapeutics

Increasingly sophisticated protein engineering efforts have been undertaken lately to generate protein therapeutics with desired properties. This has resulted in the discovery of the next generation of protein therapeutics, which include: engineered antibodies, immunoconjugates, bi/multi-specific proteins, antibody mimetic novel scaffolds, and engineered ligands/receptors. These novel protein therapeutics possess unique physicochemical properties and act via a unique mechanism-of-action, which collectively makes their pharmacokinetics (PK) and pharmacodynamics (PD) different than other established biological molecules. Consequently, in order to support the discovery and development of these next generation molecules, it becomes important to understand the determinants controlling their PK/PD. This review discusses the determinants that a PK/PD scientist should consider during the design and development of next generation protein therapeutics. In addition, the role of systems PK/PD models in enabling rational development of the next generation protein therapeutics is emphasized.

Challenges and opportunities for non-antibody scaffold drugs

The first candidates from the promising class of small non-antibody protein scaffolds are now moving into clinical development and practice. Challenges remain, and scaffolds will need to be further tailored toward applications where they provide real advantages over established therapeutics to succeed in a rapidly evolving drug development landscape.

Nonclinical evaluation of CNS-administered TPP1 enzyme replacement in canine CLN2 neuronal ceroid lipofuscinosis

The CLN2 form of neuronal ceroid lipofuscinosis, a type of Batten disease, is a lysosomal storage disorder caused by a deficiency of the enzyme tripeptidyl peptidase-1 (TPP1). Patients exhibit progressive neurodegeneration and loss of motor, cognitive, and visual functions, leading to death by the early teenage years. TPP1-null Dachshunds recapitulate human CLN2 disease. To characterize the safety and pharmacology of recombinant human (rh) TPP1 administration to the cerebrospinal fluid (CSF) as a potential enzyme replacement therapy (ERT) for CLN2 disease, TPP1-null and wild-type (WT) Dachshunds were given repeated intracerebroventricular (ICV) infusions and the pharmacokinetic (PK) profile, central nervous system (CNS) distribution, and safety were evaluated. TPP1-null animals and WT controls received 4 or 16mg of rhTPP1 or artificial cerebrospinal fluid (aCSF) vehicle every other week. Elevated CSF TPP1 concentrations were observed for 2-3 days after the first ICV infusion and were approximately 1000-fold higher than plasma levels at the same time points. Anti-rhTPP1 antibodies were detected in CSF and plasma after repeat rhTPP1 administration, with titers generally higher in TPP1-null than in WT animals. Widespread brain distribution of rhTPP1 was observed after chronic administration. Expected histological changes were present due to the CNS delivery catheters and were similar in rhTPP1 and vehicle-treated animals, regardless of genotype. Neuropathological evaluation demonstrated the clearance of lysosomal storage, preservation of neuronal morphology, and reduction in brain inflammation with treatment. This study demonstrates the favorable safety and pharmacology profile of rhTPP1 ERT administered directly to the CNS and supports clinical evaluation in patients with CLN2 disease.

Murine Models of Inflammatory Bowel Disease (IBD)

Animal models of human disease are a critical tool in both basic research and drug development. The results of preclinical efficacy studies often inform progression of therapeutic candidates through the drug development pipeline; however, the extent to which results in inflammatory bowel disease (IBD) models predict human drug response is an ongoing concern. This review discusses how murine models are currently being used in IBD research. We focus on the considerations and caveats for commonly used models in preclinical efficacy studies and discuss the value of models that utilize specific pathogenic pathways of interest rather than model all aspects of human disease.