Pure red-cell aplasia and antierythropoietin antibodies in patients treated with recombinant erythropoietin

Case Report: Pulmonary Tuberculosis Accompanied by Pure Red Cell Aplasia and Autoimmune Hemolytic Anemia

Tuberculosis is one of the most common infections worldwide. It has been associated with some hematologic disorders; however, pure red cell aplasia or autoimmune hemolytic anemia is rarely reported. We describe the case of a 68-year-old woman with pulmonary tuberculosis accompanied by pure red cell aplasia and autoimmune hemolytic anemia. These hematologic disorders were improved by treatment of pulmonary tuberculosis. This case suggests that physicians should consider the possibility of tuberculosis as a cause of pure red cell aplasia.

Case Report: Pure Red Cell Aplasia Caused by Refractory Parvovirus B19 Infection After Pancreas Transplantation Alone

A multidisciplinary team of doctors is in charge or is involved in the follow-up of patients who undergo solid organ transplantation (SOT). Immunosuppressive drugs are required after SOT, some potential unwanted side effects can be difficult to detect, and physicians must be aware of potential pitfalls. We report a case of a recipient with brittle type 1 diabetes who experienced severe and refractory anemia after pancreas transplantation alone (PTA). Despite a broad diagnostic approach for anemia, the diagnosis was delayed. The patient had normocytic normochromic anemia with severe reticulocytopenia and marked reduction or absence of erythroid precursors in the bone marrow, compatible with pure red cell aplasia (PRCA). Analyses of serological parvovirus B19 anti-IgM and anti-IgG antibodies, including PCR, were initially inconclusive/negative. The diagnosis of parvovirus B19 infection was confirmed after bone marrow biopsy with immunohistochemical staining for parvovirus B19. A retrospective analysis revealed an early post-transplant primary parvovirus B19 infection. The patient was successfully treated with intravenous immunoglobulin (IVIg) therapy. There is a risk of diagnostic delay for the less common types of anemia following SOT. Parvovirus B19 infection-associated PRCA is curable in SOT recipients and should be actively considered in patients with persistent anemia and low reticulocytes.

Anti-drug antibodies of IL-23 inhibitors for psoriasis: a systematic review

Anti-drug antibodies (ADAs) can form with certain biologic medications, but their clinical significance is not fully understood. ADA formation in psoriasis patients treated with IL-23 inhibitors was evaluated, looking at the incidence of ADAs, impact on clinical outcomes, and association with adverse events. A systematic search of PubMed, Cochrane, and Embase databases yielded 318 articles, which were manually reviewed. 19 articles met the eligibility criteria. The incidence of ADAs with the IL-23 inhibitors was as follows: 4.1% to 14.7% with guselkumab, 14% to 31% with risankizumab, and 6.5% to 18% with tildrakizumab. The incidence of neutralizing antibodies ranged from: 0% to 0.6% with guselkumab, 2% to 16% with risankizumab, and 2.5 to 3.2% with tildrakizumab. There was no evidence of reduced efficacy of psoriasis treatment with ADA presence alone. However, some studies found a reduction in clinical response with high ADA titers or with the presence of neutralizing antibodies. A few studies reported that patients with ADAs to guselkumab and risankizumab had a higher incidence of injection site reactions (ISRs). There do not appear to be other adverse events associated with ADAs with IL-23 inhibitors. Testing for presence of ADAs alone in this patient group does not appear to be predictive of treatment response. Clinically, it may be more productive to test for neutralizing antibodies or ADA titer values, although further investigation is required to show a definitive correlation.

Implementing a Clinical Immunogenicity Strategy using Preclinical Risk Assessment Outputs

Immunogenicity to biologics is often observed following dosing in human subjects during clinical trials. Both product and host specific factors may be implicated in contributing to a potential immune response. However, even if such risk factors are identified and eliminated as part of the rational quality by design approaches, the outcome in clinic can be uncertain and challenging to predict. Several tools have been employed to identify these risk factors and consequent mitigation approaches implemented prior to dosing in humans. However, the complexity of the immune system with an interplay of network of immune cells involved in driving a long- term immune response as well as patient characteristics, can make it challenging to predict the outcome in clinic. This perspective will provide an insight into recent advances in the risk assessment approaches that are utilized during preclinical stage of development of a biologic. The outputs from such tools can help to rank order and select the most optimal candidate with the least likelihood of an immune response and can further drive the development of a clinical bioanalytical and immunogenicity monitoring strategy. Such a strategy can be proactively shared with the regulators along with the proposal to streamline clinical immunogenicity and personalizing the outcome based on pharmacogenomics and other patient-related factors. This paper provides a roadmap on performing risk assessments through a systematic identification of risks and their mitigations wherever possible. Recommendations on incorporating the key components of such risk assessments as part of the new regulatory submissions are also provided. Shorter abstract Immunogenicity to biologics is common during clinical trials. Both product and host specific factors have been implicated. Several risk assessment tools can be used to identify and mitigate the risk factors responsible for immunogenicity. An insight into recent advances in the risk assessment approaches will be presented. The outputs can define a risk score and guide the clinical bioanalytical and immunogenicity monitoring strategy. A roadmap on performing risk assessments through a systematic identification of risks and their mitigations wherever possible is provided. Best practices for a risk assessment strategy and recommendations on the content for IND and the Integrated summary of Immunogenicity are also provided.

Investigating Severe Adverse Reactions: Examples of the ANTICIPATE Methodology at Work

Severe adverse drug reactions (sADRs) are important causes of morbidity and mortality. The Southern Network on Adverse Drug Reactions (SONAR), a National Cancer Institute-funded pharmacovigilance program, has outlined a novel 9-stop methodology, termed ANTICIPATE, that has evaluated this methodology, among persons with chronic kidney disease (CKD).

Regulatory Evaluation of Biosimilars: Refinement of Principles Based on the Scientific Evidence and Clinical Experience

The World Health Organization (WHO) guidelines on evaluation of similar biotherapeutic products (SBPs; also called biosimilars) were adopted by the WHO Expert Committee on Biological Standardization (ECBS) in 2009. In 2019, the ECBS considered that a more tailored and potentially reduced clinical data package may be acceptable in cases where this was clearly supported by the available scientific evidence. The goal of this publication is to review the current clinical experience and scientific evidence and to provide an expert perspective for updating the WHO guidelines to provide more flexibility and clarity. As the first step, the relevant guidelines by other regulatory bodies were reviewed in order to identify issues that might help with updating the WHO guidelines. Next, a literature search was conducted for information on the long-term efficacy, safety, and immunogenicity of biosimilars to identify possible long-term problems. Finally, a search for articles concerning the role of clinical studies in the benefit-risk evaluation of biosimilars was conducted. The analysis of other guidelines suggested that the WHO guidelines may need more emphasis on the importance of the state-of-the-art physicochemical and structural comparability exercise and in vitro functional testing. The use of "foreign" reference product will also need clarifications. The value of in vivo toxicological tests in the development of biosimilars is questionable, and the non-clinical part needs revisions accordingly. The concepts of "totality of evidence," "stepwise development," and "residual uncertainty" were applied in the evaluation of the clinical sections of the guideline. The review of long-term safety and efficacy demonstrated the robustness of the current biosimilar development concept. The analysis of the roles of different development phases suggested that the large efficacy, safety, and immunogenicity studies are, in most cases, redundant. The residual uncertainty of safety, immunogenicity, and efficacy of biosimilars that has shaped the current regulatory guidelines is now substantially reduced. This will allow the re-evaluation of the non-clinical and clinical requirements of the current WHO main guideline. The shift of the relative impact of the development phases towards physico-chemical and in vitro functional testing will provide a relief to the manufacturers and new challenges to the regulators.

Achieving efficacy in subjects with sustained pegvaliase-neutralizing antibody responses

Pegvaliase (Palynziq®) is an enzyme substitution therapy using PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL) to reduce blood phenylalanine (Phe) levels in adults with phenylketonuria (PKU). In Phase 3 clinical studies, all subjects treated with pegvaliase developed anti-drug antibodies. To specifically evaluate pegvaliase-neutralizing antibodies (NAbs) and assess impact on pegvaliase efficacy, a novel hybrid ligand-binding/tandem mass spectrometry NAb assay was developed. Analysis of Phase 3 study samples revealed that pegvaliase NAb titers developed during early treatment (≤6 months after treatment initiation), and then plateaued and persisted in the majority of subjects during late treatment (>6 months). Subjects with the lowest/undetectable NAb titers had relatively high plasma pegvaliase concentrations and experienced the most rapid decline in blood Phe concentrations at relatively low pegvaliase dose concentrations. In contrast, subjects with higher NAb titers generally had lower plasma pegvaliase concentrations on similar low doses, with little change in blood Phe concentrations. However, with additional time on treatment and individualized dose titration, the majority of subjects achieved substantial and sustained blood Phe reduction, including those with higher NAb titers. Moreover, after maturation of the anti-pegvaliase immune response, NAb titers were stable over time and did not rise in response to dose increases; thus, subjects did not require additional dose increases to maintain reduction in blood Phe.

Challenging patient phenotypes in the management of anaemia of chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is often complicated by anaemia, which is associated with disease progression and increased hospital visits, decreased quality of life, and increased mortality.

METHODS

A comprehensive literature search of English language peer-reviewed articles in PubMed/MedLine published between 1998 and 2020 related to the treatment of anaemia of CKD was conducted. The United States Renal Database System and Dialysis Outcomes and Practice Patterns Study (DOPPS) data reports, the Centers for Disease Control and Prevention and the US Food and Drug Administration websites, and published congress abstracts in 2020 were surveyed for relevant information.

RESULTS

Subgroups of patients with anaemia of CKD present a clinical challenge throughout the disease spectrum, including those with end-stage kidney disease, advanced age or resistance to or ineligibility for current standards of care (ie, oral or intravenous iron supplementation, erythropoietin-stimulating agents and red blood cell transfusions). In addition, those with an increased risk of adverse events because of comorbid conditions, such as cardiovascular diseases or diabetes, comprise special populations of patients with an unmet need for interventions to improve clinical outcomes. These comorbidities must be managed in parallel and may have a synergistic effect on overall disease severity.

CONCLUSIONS

Several therapies provide promising opportunities to address gaps with a standard of care, including hypoxia-inducible factor prolyl hydroxylase inhibitors, which stimulate haematopoiesis through promoting modest increases in serum erythropoietin and improved iron homeostasis. The critical issues in the management of anaemia of CKD in these challenging phenotypes and the clinical utility of new therapeutic agents in development for the treatment of anaemia of CKD should be assessed and the information should be made available to healthcare providers.

Multi-Organs-on-Chips for Testing Small-Molecule Drugs: Challenges and Perspectives

Organ-on-a-chip technology has been used in testing small-molecule drugs for screening potential therapeutics and regulatory protocols. The technology is expected to boost the development of novel therapies and accelerate the discovery of drug combinations in the coming years. This has led to the development of multi-organ-on-a-chip (MOC) for recapitulating various organs involved in the drug-body interactions. In this review, we discuss the current MOCs used in screening small-molecule drugs and then focus on the dynamic process of drug absorption, distribution, metabolism, and excretion. We also address appropriate materials used for MOCs at low cost and scale-up capacity suitable for high-performance analysis of drugs and commercial high-throughput screening platforms.

Comparability study of monocyte derived dendritic cells, primary monocytes, and THP1 cells for innate immune responses

Immunogenicity is one major challenge to the successful development of biotherapeutics because it could adversely affect PK/PD, safety, and efficacy. Preclinical immunogenicity risk assessment strategies and assays have been developed and implemented to screen and optimize discovery molecules. Internalization by antigen presenting cells (APC) and innate immune activation are initial prerequisite steps in eliciting immune responses to biotherapeutics. Dendritic cells (DC)- and monocyte-based assays are employed to interrogate such risks, and their value has been well documented in the literature. However, these assays have limited throughput, exhibit higher variability, and entail lengthy and complex procedures as they are based on primary cells such as peripheral blood mononuclear cells (PBMC) from individual donors. Herein, we investigated THP1 cells as surrogate cells to study APC internalization and innate immune activation. Comparability studies showed that THP1 cells could resemble innate immune responses of monocyte-derived DC and primary CD14+ monocytes using a panel of therapeutic antibodies. In addition, an automated high throughput THP1 internalization assay was qualified to enable risk assessment at pre‑lead stages. The results demonstrated that THP1 cells can be utilized to assess immunogenicity risk in a high throughput manner.

Identifiability of Biologicals: An Analysis Using EudraVigilance, the European Union's Database of Reports of Suspected Adverse Drug Reactions

The relevance of biological therapies for an increasing number of conditions is on the rise. Following the expiry of the initial period of market exclusivity, many of these successful therapies have seen the arrival of biosimilars on the market. The clear identification of the precise medicine responsible for an adverse drug reaction (ADR) report is an important element for pharmacovigilance, allowing timely detection of potential product-specific safety signals. We looked at the identifiability of biologicals up to the level of commercial product name in ADR reports received from European clinical practice between 2011 and December 2019. A good level of identification (91.5%) was observed overall, but at the same time a downward trend was observed in the last 5 years. This reduction in the level of identifiability of biological products (originators and biosimilars) at the commercial name level in general was driven by five widely used substances, whereas the identification of all other biologics stayed consistent over time (at over 90%). We observed that those five substances were used mostly within oncology. The introduction of the first biosimilar in the market did not appear to affect their identifiability. These results show that although the general level of identification at the commercial product name level in ADRs in Europe is robust and generally stable over time, decreasing trends can be down to a few commonly used substances, which need to be monitored to reverse the trend.

Aggregation of protein therapeutics enhances their immunogenicity: causes and mitigation strategies

Protein aggregation in biotherapeutics has been identified to increase immunogenicity, leading to immune-mediated adverse effects, such as severe allergic responses including anaphylaxis. The induction of anti-drug antibodies (ADAs) moreover enhances drug clearance rates, and can directly block therapeutic function. In this review, identified immune activation mechanisms triggered by protein aggregates are discussed, as well as physicochemical properties of aggregates, such as size and shape, which contribute to immunogenicity. Furthermore, factors which contribute to protein stability and aggregation are considered. Lastly, with these factors in mind, we encourage an innovative and multidisciplinary approach with regard to further research in the field, with the overall aim to avoid immunogenic aggregation in future drug development.

Human iPSC-derived neural crest stem cells can produce EPO and induce erythropoiesis in anemic mice

Inadequate production of erythropoietin (EPO) leads to anemia. Although erythropoiesis-stimulating agents can be used to treat anemia, these approaches are limited by high costs, adverse effects, and the need for frequent injections. Developing methods for the generation and transplantation of EPO-producing cells would allow for the design of personalized and complication-free therapeutic solutions. In mice, the first EPO source are neural crest cells (NCCs), which ultimately migrate to the fetal kidney to differentiate into EPO-producing fibroblasts. In humans however, it remains unknown whether NCCs can produce EPO in response to hypoxia. Here, we developed a new protocol to differentiate human induced pluripotent stem cells (hiPSCs) into NCCs and showed that cthese cells can produce functional EPO that can induce human CD34⁺ hematopoietic progenitor differentiation into erythroblasts in vitro. Moreover, we showed that hiPSC-derived NCCs can be embedded in clinical-grade atelocollagen scaffolds and subcutaneously transplanted into anemic mice to produce human EPO, accelerate hematocrit recovery, and induce erythropoiesis in the spleen. Our findings provide unprecedented evidence of the ability of human NCCs to produce functional EPO in response to hypoxia, and proof-of-concept for the potential clinical use of NCC-containing scaffolds as cell therapy for renal and non-renal anemia.

Acquired Pure Red Cell Aplasia and Recombinant Erythropoietin

Recombinant erythropoietin (rEPO)-associated immunologically driven acquired pure red cell aplasia (PRCA) is an underreported, potentially worsening clinical syndrome in the setting of treatment of anemia of chronic kidney disease. Most cases reported in world literature are related to different formulations of erythropoiesis-stimulating agents with an implication in diagnosis and management. This brief review highlights the clinical guidelines of rEPO usage in nephrology practice, the pathophysiologic mechanism of PRCA, clinical features, diagnosis, and suggested management protocols.

Extrapolation: Experience gained from original biologics

Biologicals undergo modifications throughout their commercial lifecycle. Major changes can unintentionally magnify their inherent physicochemical variability. Although trials comparing the pre- and the post-change versions have been requested occasionally, analytical comparison is the most sensitive approach to anticipating clinical equivalence. Therefore, it may be concluded, by means of 'extrapolation', that non-identical versions of a given biologic will behave equally in all indications. Despite the lessons learned with original biologics, there are still controversies around the approval of biosimilars through extrapolation. Here, a comprehensive analysis of scattered information allows for an account of cases of original biologic versions approved in some indications with no patient trials involved. Healthcare professionals can be reassured that inasmuch as extrapolation has proven valid for new versions of original biologics, the same holds for biosimilars.

Successful application of roxadustat in the treatment of patients with anti-erythropoietin antibody-mediated renal anaemia: a case report and literature review

Recombinant human erythropoietin (rHuEPO) has been used worldwide for treatment of renal anaemia due to its good curative effect. However, rHuEPO treatment is associated with a rare but severe complication because of the development of anti-EPO antibodies, which are difficult to treat. Currently, the main treatments for the anti-EPO antibodies include withdrawing the rHuEPO, providing blood transfusions and administrating steroid-based immunosuppressive agents. Although the above methods can alleviate anti-EPO-related anaemia, there are obvious side-effects such as decreased immunity and an increased risk of infection. Therefore, accurately identifying anti-EPO-related anaemia and effectively treating this complication is worth exploring. This current case report describes a 49-year-old female patient with chronic kidney disease that received rHuEPO subcutaneously and then developed anti-EPO antibody-mediated renal anaemia with her haemoglobin levels dropping to 37 g/l. The patient refused to be treated with steroids, so she received 120 mg roxadustat administered orally every 72 h and her Hb level increased to 110 g/l over a few months. This current case report demonstrates that roxadustat can be used to successfully treat anti-EPO antibody-mediated renal anaemia without the use of steroid-based immunosuppressants.

Immune response with long-term memory triggered by amorphous aggregates of misfolded anti-EGFR VHH-7D12 is directed against the native VHH-7D12 as well as the framework of the analogous VHH-9G8

We previously demonstrated that amorphous aggregates of misfolded V_HH-7D12 antibodies (V_HH-Mis), a potential anti-EGFR drug, can generate a robust serum IgG response. Here we investigate the immunogenic nature, especially the specificity of the immune response induced by V_HH-Mis. To this end, we used two natively folded and 77% identical anti-EGFR V_HHs (V_HH-7D12 and V_HH-9G8) that possess a common framework but distinct complementarity determining regions (CDRs). In 60% of mice immunized with V_HH-Mis, the anti-V_HH-7D12 IgG titer was stronger than the anti-V_HH-9G8 titer (Group-1). In the remaining mice (40%; Group-2), the anti-V_HH-7D12 and anti-V_HH-9G8 titer were almost identical. We rationalized these results by hypothesizing that mice in Group-1 produced IgG mostly against the V_HH-7D12's CDRs, whereas in Group-2 mice, they targeted the V_HH's framework. The IgG specificity against V_HH-7D12 and V_HH-9G8 was essentially unchanged over 17 weeks in both groups. Further, in all mice (Group-1&2) re-immunized with native V_HH-7D12, the IgG titer against V_HH-7D12 increased sharply but not against V_HH-9G8. On the other hand, none of the three Group-1 mice re-immunized with native V_HH-9G8 showed immunogenicity against V_HH-7D12 nor V_HH-9G8. Whereas, in Group-2 mice (three/three) re-immunized with V_HH-9G8, the IgG titers against both V_HHs increased but slowly. Flow-cytometric studies showed that V_HH-Mis immunized mice generated a higher number of effector and central memory T-cells. Overall, these observations indicate that amorphous aggregates made of a misfolded V_HH can induce serum IgG against its natively folded self and analogous V_HHs having a similar framework but distinct CDRs. Furthermore, a robust long-term immune response with memory was established against its natively folded self but with a nil-to-moderate immune response against natively folded V_HH analogs.

How I manage acquired pure red cell aplasia in adults

Pure red cell aplasia (PRCA) is a rare hematological disorder with multiple etiologies. The multifaceted nature of this disease is emphasized by the variety of concomitant clinical features. Classic idiopathic presentation aside, prompt recognition of pathogenetic clues is important because of their diagnostic and therapeutic implications. As a consequence, treatment of PRCA is diverse and strictly dependent on the presented clinical scenario. Here, we propose a series of clinical vignettes that showcase instructive representative situations derived from our routine clinical practice. Using these illustrative clinical cases, we review the diagnostic workup needed for a precise diagnosis and the currently available therapeutic options, discussing their applications in regard to the various PRCA-associated conditions and individual patients' characteristics. Finally, we propose a treatment algorithm that may offer guidance for personalized therapeutic recommendations.

Interchangeability of Biosimilars: What Level of Clinical Evidence is Needed to Support the Interchangeability Designation in the United States?

A biosimilar is a biologic drug that is "highly similar to a reference (originator) product, with no clinically meaningful differences between the two products in safety, purity, and potency". Regulatory approval of a biosimilar is based on analytical, structural, and functional comparisons with the reference product, comparative nonclinical (in vivo) studies, clinical pharmacokinetics and/or pharmacodynamics, and immunogenicity. In addition, comparative clinical efficacy and safety assessments are usually conducted and, taken together, comprise the "totality of the evidence" supporting biosimilarity. For a biosimilar to meet the additional designation of interchangeability in the United States (US), the applicant must demonstrate that the biological drug can be expected to produce the "same clinical result as the reference product in any given patient" and "if the biological drug is administered more than once to an individual, the risk in terms of safety or diminished efficacy of alternating or switching between the use of the biological drug and the reference product is no greater than the risk of using the reference product without such alternation or switch". The challenges faced in conducting clinical studies to support a designation of interchangeability, as defined in the final interchangeability guidance from the US Food and Drug Administration, are considered. Potential alternative approaches to generating adequate and sufficient clinical data to support a designation of interchangeability are also presented.

Evolving Role of Pharmacogenetic Biomarkers to Predict Drug-Induced Hematological Disorders

ABSTRACT

Drug-induced hematological disorders constitute up to 30% of all blood dyscrasias seen in the clinic. Hematologic toxicity from drugs may range from life-threatening marrow aplasia, agranulocytosis, hemolysis, thrombosis to mild leukopenia, and thrombocytopenia. Pathophysiologic mechanisms underlying these disorders vary from an extension of the pharmacological effect of the drug to idiosyncratic and immune-mediated reactions. Predicting these reactions is often difficult, and this makes clinical decision-making challenging. Evidence supporting the role of pharmacogenomics in the management of these disorders in clinical practice is rapidly evolving. Despite the Clinical Pharmacology Implementation Consortium and Pharmacogenomics Knowledge Base recommendations, few tests have been incorporated into routine practice. This review aims to provide a comprehensive summary of the various drugs which are implicated for the hematological adverse events, their underlying mechanisms, and the current evidence and practical recommendations to incorporate pharmacogenomic testing in clinical care for predicting these disorders.

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.

Characterization of robust immune responses to a bispecific antibody, a novel class of antibody therapeutics

Background: Anti-A/B is a bispecific monoclonal antibody that blocks activities of soluble targets A and B. Robust immune responses were observed in a multiple-dose cynomolgus monkey toxicology study, negatively impacting the toxicokinetics/pharmacodynamics profile of anti-A/B in some animals. This was unexpected as similar findings were not observed in the two previously studied parental molecules. Methodology & Results: This paper discusses our characterization strategy for evaluating the immunogenic domain(s) of anti-A/B and our mitigation plan to monitor immunogenicity in the first-in-human clinical study. The characterization results from the cynomolgus monkey and Phase I studies are discussed. Conclusion: The characterization strategy discussed informed understanding of immunogenicity results and clinical impact, which can be broadly applied to other molecules with multiple-binding domains.

Immunogenicity Challenges Associated with Subcutaneous Delivery of Therapeutic Proteins

The subcutaneous route of administration has provided convenient and non-inferior delivery of therapeutic proteins compared to intravenous infusion, but there is potential for enhanced immunogenicity toward subcutaneously administered proteins in a subset of patients. Unwanted anti-drug antibody response toward proteins or monoclonal antibodies upon repeated administration is shown to impact the pharmacokinetics and efficacy of multiple biologics. Unique immunogenicity challenges of the subcutaneous route have been realized through various preclinical and clinical examples, although subcutaneous delivery has often demonstrated comparable immunogenicity to intravenous administration. Beyond route of administration as a treatment-related factor of immunogenicity, certain product-related risk factors are particularly relevant to subcutaneously administered proteins. This review attempts to provide an overview of the mechanism of immune response toward proteins administered subcutaneously (subcutaneous proteins) and comments on product-related risk factors related to protein structure and stability, dosage form, and aggregation. A two-wave mechanism of antigen presentation in the immune response toward subcutaneous proteins is described, and interaction with dynamic antigen-presenting cells possessing high antigen processing efficiency and migratory activity may drive immunogenicity. Mitigation strategies for immunogenicity are discussed, including those in general use clinically and those currently in development. Mechanistic insights along with consideration of risk factors involved inspire theoretical strategies to provide antigen-specific, long-lasting effects for maintaining the safety and efficacy of therapeutic proteins.

BSTP Review of 12 Case Studies Discussing the Challenges, Pathology, Immunogenicity, and Mechanisms of Inhaled Biologics

The inhalation route is a relatively novel drug delivery route for biotherapeutics and, as a result, there is a paucity of published data and experience within the toxicology/pathology community. In recent years, findings arising in toxicology studies with inhaled biologics have provoked concern and regulatory challenges due, in part, to the lack of understanding of the expected pathology, mechanisms, and adversity induced by this mode of delivery. In this manuscript, the authors describe 12 case studies, comprising 18 toxicology studies, using a range of inhaled biotherapeutics (monoclonal antibodies, fragment antigen-binding antibodies, domain antibodies, therapeutic proteins/peptides, and an oligonucleotide) in rodents, nonhuman primates (NHPs), and the rabbit in subacute (1 week) to chronic (26 weeks) toxicology studies. Analysis of the data revealed that many of these molecules were associated with a characteristic pattern of toxicity with high levels of immunogenicity. Microscopic changes in the airways consisted of a predominantly lymphoid perivascular/peribronchiolar (PV/PB) mononuclear inflammatory cell (MIC) infiltrate, whereas changes in the terminal airways/alveoli were characterized by simple ("uncomplicated") increases in macrophages or inflammatory cell infiltrates ranging from mixed inflammatory cell infiltration to inflammation. The PV/PB MIC changes were considered most likely secondary to immunogenicity, whereas simple increases in alveolar macrophages were most likely secondary to clearance mechanisms. Alveolar inflammatory cell infiltrates and inflammation were likely induced by immune modulation or stimulation through pharmacologic effects on target biology or type III hypersensitivity (immune complex disease). Finally, a group of experts provide introductory thoughts regarding the adversity of inhaled biotherapeutics and the basis for reasonable differences of opinion that might arise between toxicologists, pathologists, and regulators.

Modified recombinant human erythropoietin with potentially reduced immunogenicity

Recombinant human erythropoietin (rHuEPO) is a biopharmaceutical drug given to patients who have a low hemoglobin related to chronic kidney disease, cancer or anemia. However, some patients repeatedly receiving rHuEPO develop anti-rHuEPO neutralizing antibodies leading to the development of pure red cell aplasia (PRCA). The immunogenic antibody response activated by rHuEPO is believed to be triggered by T-cells recognizing EPO epitopes bound to MHC molecules displayed on the cell surface of APCs. Previous studies have reported an association between the development of anti-rHuEpo-associated PRCA and the HLA-DRB1*09 gene, which is reported to be entrenched in the Thai population. In this study, we used computational design to screen for immunogenic hotspots recognized by HLA-DRB1*09, and predicted seventeen mutants having anywhere between one through four mutations that reduce affinity for the allele, without disrupting the structural integrity and bioactivity. Five out of seventeen mutants were less immunogenic in vitro while retaining similar or slightly reduced bioactivity than rHuEPO. These engineered proteins could be the potential candidates to treat patients who are rHuEpo-dependent and express the HLA-DRB1*09 allele.

Report on biopharmaceutical profile of recent biotherapeutics and insilco docking studies on target bindings of known aptamer biotherapeutics

Accumulated Toxicity, disease recurrence and drug resistivity problems have been observed due to the synthetic and semisynthetic therapeutic practices, which alternatively led to focus on Bio-therapeutics production than xenobiotics. Quick plasma clearance and high potency are the reasons for trending research with huge pharma market of numerous Bio-therapeutics than ever before. Researchers proved that most of the nano and micro Bio-therapeutics have multiple beneficial therapeutic effects. We have analyzed the past, and present scenario of some notable clinically approved Bio-therapeutics to identify the future formulation needs with advanced techniques. Protein-related drugs are the foremost Bio-therapeutics such as antibodies, enzymes, and short, fragmented polypeptides show aggregation properties during storage, naked peptide moieties are resisted by the polar cell membrane, and also the antidrug antibodies were reported. Even though Nucleic acid nano-bodies are excellent target binders than proteins, they had only a few minutes of half-life. Maintaining homogeneousness upon storage of Bio-therapeutics is still a significant challenge in industrial-scale formulation. Notably, plant systems are identified as most useful cost-effective hosts to produce human enzymes than animal systems without any possible viral loads. Irrespective of numerous advancements in routes of administration and additives, subcutaneous is still a golden one to achieve better dynamics. Additionally, the interactions and effective bonds made by each class of well-known aptamer biotherapeutics which are considered as future drugs were studied.

The Impact of Product and Process Related Critical Quality Attributes on Immunogenicity and Adverse Immunological Effects of Biotherapeutics

The pharmaceutical industry has experienced great successes with protein therapeutics in the last two decades and with novel modalities, including cell therapies and gene therapies, more recently. Biotherapeutics are complex in structure and present challenges for discovery, development, regulatory, and life cycle management. Biotherapeutics can interact with the immune system that may lead to undesired immunological responses, including immunogenicity, hypersensitivity reactions (HSR), injection site reactions (ISR), and others. Many product and process related critical quality attributes (CQAs) have the potential to trigger or augment such immunological responses to the product. Tremendous efforts, both clinically and preclinically, have been invested to understand the impact of product and process related CQAs on adverse immunological effects. The information and knowledge are critical for the implementation of Quality by Design (QbD), which requires risk assessment and establishment of specifications and control strategies for CQAs. A quality target product profile (QTPP) that identifies the key CQAs through process development can help assign severity scores based on safety, immunogenicity, pharmacokinetics (PK) and pharmacodynamics (PD) of the molecule. Gaps and future directions related to biotherapeutics and emerging novel modalities are presented.

De novo design of potent and resilient hACE2 decoys to neutralize SARS-CoV-2

We developed a de novo protein design strategy to swiftly engineer decoys for neutralizing pathogens that exploit extracellular host proteins to infect the cell. Our pipeline allowed the design, validation, and optimization of de novo human angiotensin-converting enzyme 2 (hACE2) decoys to neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The best monovalent decoy, CTC-445.2, bound with low nanomolar affinity and high specificity to the receptor-binding domain (RBD) of the spike protein. Cryo-electron microscopy (cryo-EM) showed that the design is accurate and can simultaneously bind to all three RBDs of a single spike protein. Because the decoy replicates the spike protein target interface in hACE2, it is intrinsically resilient to viral mutational escape. A bivalent decoy, CTC-445.2d, showed ~10-fold improvement in binding. CTC-445.2d potently neutralized SARS-CoV-2 infection of cells in vitro, and a single intranasal prophylactic dose of decoy protected Syrian hamsters from a subsequent lethal SARS-CoV-2 challenge.

Current Considerations for Immunoglobulin Isotype Characterization of Antibody Response against Biotherapeutics

The ability of biotherapeutics to induce immune response in patients has been broadly accepted. Humoral immune response to biotherapeutics is expected to be polyclonal in nature with a high degree of diversity, including treatment-induced anti-drug antibodies (ADA) immunoglobulin isotype composition. Therapeutics with strong potential to induce immunity may produce a T cell-dependent response resulting in a gradual transition from initial IgM based to mature, IgG-based ADAs. Immunoglobulin class switch and transition to high affinity IgG1 and IgG4 antibodies were linked to a reduced drug efficacy, accelerated clearance, development of drug neutralizing antibodies, and modulation of hypersensitivity reaction rates. Examples presented herein demonstrate that understanding of isotype composition of ADA response can be highly important to predict future of disease progression. Isotype characterization of ADA response can be viewed highly useful, particularly for high immunogenicity risk biotherapeutics although may be less relevant or used as a research tool only for medium and low immunogenicity risk level therapeutics. Isotype-specific characteristics, methods of detection, and several case studies are presented herein.

Pure Red-Cell Aplasia “Epidemic”—Mystery Completely Revealed?

Starting in 1998, the number of pure red-cell aplasia (PRCA) cases in patients treated with recombinant human erythropoietin (rHuEPO) increased dramatically. Most cases were observed in patients treated with epoetin alfa produced outside the United States. The peak was observed in 2002; since then, the PRCA incidence has declined.

Many factors are likely to have contributed to this upsurge. The molecular structure of the various epoetins and patient characteristics do not seem to play a major role. The route of administration holds some importance, because most PRCA patients received rHuEPO subcutaneously. The peak of PRCA cases overlapped with the removal of human serum albumin from the Eprex formulation (Janssen-Pharmaceutica NV, Beerse, Belgium), for which polysorbate 80 and glycine were substituted. Polysorbate 80 may have increased the immunogenicity of Eprex by eliciting the formation of epoetin-containing micelles or by interacting with leachates released by the uncoated rubber stoppers of prefilled syringes. Compared with the previous formulation, the polysorbate 80 formulation has lower stability, making it more susceptible to stress conditions such as insufficient attention to the cold chain. This situation could facilitate protein denaturation or aggregate formation.

Uncoated rubber stoppers were replaced with coated stoppers, and the cold chain was reinforced; the Eprex formulation has remained unchanged.

Even though the incidence of PRCA returned to very low levels, discriminating the cause–effect relationship of a single action is difficult, given that all occurred with a similar chronology, and that PRCA develops after a relatively long exposure period. Careful observation of future trends of new PRCA cases is thus mandatory.

An innovative method for characterizing neutralizing antibodies against antibody-derived therapeutics

Detection of anti-drug antibodies (ADA) that have a neutralizing capacity is an important aspect of immunogenicity evaluation during development of biotherapeutics, but developing and validating neutralizing antibody (NAb) assays that show direct interference of a biologic function is a challenging and resource-intensive activity. In particular, the need for adequate drug and target tolerance often requires extensive pre-treatment steps that limit assay sensitivity compared with a typical bridging-format assay used to detect binding ADA. Such limitations may complicate data interpretation as a positive ADA followed by a negative NAb result could be due to the presence of non-neutralizing antibodies or could be a false-negative for NAbs due to methodology differences. To address such issues, we developed a novel assay for Nanobodies® and other antibody-derived therapeutics that solely detects ADA directed against the complementarity-determining regions (CDRs) involved in drug-target interactions. This was achieved by creating a "null variant" of the therapeutic drug, which has mutated CDRs rendering it non-functional for target binding but is otherwise identical to the drug compound. Non-CDR-binding antibodies are pre-complexed with the null variant of the Nanobody leaving only CDR-binding ADA with neutralizing potential (ANP) to be detected in this assay, which is called a NAb Epitope Characterization Assay (NECA). Method qualification results confirmed highly comparable assay characteristics (sensitivity, drug tolerance, selectivity and precision) of both the NECA and a validated ADA assay for the same Nanobody. A panel of purified neutralizing and non-neutralizing antibodies as well as non-clinical and clinical samples were used to further substantiate the fit-for-purpose and advantages of this novel assay format to detect ANP. In the clinical case study, a 20 to 40-fold difference in assay sensitivity existed between the validated ADA assay and NAb assay, which complicated data interpretation. Implementation of the NECA allowed unambiguous comparison of the levels of binding ADA and ANP in study samples which enabled us to delineate the true neutralizing capacity of the responses. Depending on the risk of the therapeutic, this method could be a valuable alternative for NAb testing by enabling earlier detection of ADA with neutralizing potential and ensuring adequate immunogenicity risk assessment.

Long-Term Consequences of High Titer Neutralizing Antibodies to Interferon-β in Multiple Sclerosis

Background

Neutralizing anti-drug antibodies (NAbs) to interferon beta (IFNβ) develop in up to 47% of multiple sclerosis (MS) treated patients inhibiting treatment effect of IFNβ. However, the long-term effect of NAbs remain unknown.

Objective

To investigate the long-term consequences of high titer NAbs to IFNβ on disease activity and progression in MS patients.

Methods

An observational study including data from all IFNβ treated relapsing remitting MS patients with sufficient NAb test results from the Swedish MS registry. Patients were classified into either confirmed ‘high titer’ or ‘persistent negative’ groups and analyzed for differences in disease activity and progression over time.

Results

A total of 197 high-titer and 2907 persistent negative patients with 19969.6 follow up years of data were included. High titer NAbs were associated with a higher degree of disease activity at baseline. However, even when accounting for this, the presence of high titer NAbs were also associated with higher disease activity during IFNβ treatment. This persisted even after the next DMT start, suggesting that earlier high titers may partially reduce the effect of later treatments. No difference was found in confirmed disability progression.

Conclusion

High titer NAbs to IFNβ are associated with higher disease activity, persisting even after IFNβ discontinuation or switch. These results support use of highly efficient treatment earlier in patients with active disease, to avoid these complications.

Resolution of epoetin-induced pure red cell aplasia, successful re-challenge with roxadustat

The application of erythropoietin (EPO) can bring about a rare but serious complication called anti‐EPO antibody‐mediated pure red cell aplasia (PRCA). Once the disease is diagnosed, EPO administration should be stopped immediately. However, after the removal of the anti‐EPO antibody, treating anaemia in these patients with chronic renal disease with EPO therapy is difficult, as restarting EPO therapy risks the recurrence of anti‐EPO antibody‐mediated PRCA. A 26‐year‐old man with anaemia related to renal failure, who was administered recombinant human EPO subcutaneously, developed anti‐EPO antibody‐mediated PRCA. After removal of antibodies by treatment with corticosteroids and cyclosporine, therapy for anaemia of chronic renal disease with roxadustat achieved good results. Roxadustat is a new type of drug for the treatment of anaemia, and it can stimulate endogenous EPO within or near the physiologic range and increase haemoglobin levels.

[Biosimilar medicines: Regulatory issues and medico-economic impacts]

Le concept de médicament biosimilaire a été lancé par les directives européennes de 2001 et 2004 avec les premières autorisations européennes de mise sur le marché (AMM) délivrées en 2006. Ce sont des « copies » de médicaments biologiques, pour la plupart des protéines. Compte tenu de la variabilité inhérente aux processus de « synthèse biologique » quelques variations de la structure chimique du produit fini peuvent être observées sur les résidus glycosylés mais pas sur la séquence d’acides aminés pour les protéines. Pour cette raison, le dossier de demande d’AMM de ces produits, contrairement aux génériques, doit comporter une démonstration d’équivalence thérapeutique dans au moins l’une des indications thérapeutiques du princeps. C’est l’arrivée des biosimilaires des anticorps monoclonaux qui a vraiment marqué leur avènement avec les biosimilaires d’infliximab, d’étanercept et d’adalimumab dans les domaines de la rhumatologie, gastroentérologie et dermatologie, puis dans les domaines de la cancérologie avec les biosimilaires de rituximab, trastuzumab et enfin bévacizumab. Si l’arrivée des biosimilaires réduit le risque de ruptures d’approvisionnement des produits princeps, leur intérêt est principalement économique, permettant la réduction du prix des traitements face aux princeps biologiques coûteux. Avec l’expérience acquise, les réticences à l’interchangeabilité des produits se sont estompées.

Design and Evaluation of a Multiplexed Assay to Assess Human Immunogenicity Against Humira®

The use of biologic-based therapeutics has revolutionized our ability to treat complex diseases such as cancer- and autoimmune-related disorders. Biologic-based therapeutics are known to generate anti-drug immune responses or immunogenicity in clinical patients which can lead to altered pharmacokinetics, decreased drug efficacy, and unwanted adverse clinical events. Assays designed to detect and assess anti-drug immune responses are used to help monitor patients and improve drug safety. Utilizing a tiered approach, screening assays are developed first to identify patients that are potentially positive for anti-drug-specific antibodies. Patients that screen positive are subjected to additional tiers of testing that include a confirmation assay to confirm the presence of expected anti-drug-specific antibodies, a titer assay to assess relative levels of anti-drug-specific antibodies, and, depending on the drug's mechanism of action or concerns of adverse clinical reactions, further characterization such as drug neutralization and anti-drug antibody isotyping. This tiered approach can prove to be detrimental to clinical samples from exposure to multiple cycles of testing, freeze thaws, and repeated handling by lab personnel. Multiplexing some of these assays together may streamline the characterization of anti-drug immune responses and help reduce the repeated usage of clinical samples. In this study, we combined a screening assay and anti-drug isotyping assays into one multiplexed assay using the Luminex® xMAP® Technology. The multiplexed assay was developed and validated to meet the FDA recommended guidelines for immunogenicity assessments. These results show that multiplexed assays perform comparably to industry standards. This study should encourage labs to explore the use of multiplexing immunogenicity assays to characterize anti-drug antibody responses quickly, with less repeat testing and reduced sample handling.

De novo design of ACE2 protein decoys to neutralize SARS-CoV-2

There is an urgent need for the ability to rapidly develop effective countermeasures for emerging biological threats, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the ongoing coronavirus disease 2019 (COVID-19) pandemic. We have developed a generalized computational design strategy to rapidly engineer de novo proteins that precisely recapitulate the protein surface targeted by biological agents, like viruses, to gain entry into cells. The designed proteins act as decoys that block cellular entry and aim to be resilient to viral mutational escape. Using our novel platform, in less than ten weeks, we engineered, validated, and optimized de novo protein decoys of human angiotensin-converting enzyme 2 (hACE2), the membrane-associated protein that SARS-CoV-2 exploits to infect cells. Our optimized designs are hyperstable de novo proteins (∼18-37 kDa), have high affinity for the SARS-CoV-2 receptor binding domain (RBD) and can potently inhibit the virus infection and replication in vitro. Future refinements to our strategy can enable the rapid development of other therapeutic de novo protein decoys, not limited to neutralizing viruses, but to combat any agent that explicitly interacts with cell surface proteins to cause disease.

Long-term Safety of Epoetin Alfa-epbx for the Treatment of Anemia in ESKD: Pooled Analyses of Randomized and Open-label Studies

Rationale & Objective

Epoetin alfa-epbx is a biosimilar to the reference product, epoetin alfa. We compare the safety of epoetin alfa-epbx versus epoetin alfa based on a pooled analysis of findings from 2 randomized, double-blind, comparative clinical studies, and report new data for the long-term safety of epoetin alfa-epbx.

Study Design

Pooled analyses of previously conducted studies.

Setting & Participants

Hemodialysis patients with anemia.

Interventions

Data from patients who received 1 or more subcutaneous or intravenous doses of study drug were integrated across route of administration in combined randomized groups (epoetin alfa-epbx, n = 423; epoetin alfa, n = 426). Data from patients who received 1 or more doses of epoetin alfa-epbx in either open-label extension trial were integrated across route of administration in a combined long-term safety studies group (n = 576).

Outcomes

Adverse events (AEs), immunogenicity, and other outcomes were assessed.

Results

Incidences of treatment-emergent AEs, serious AEs, and discontinuation of study drug treatment because of treatment-emergent AEs were similar between combined randomized epoetin alfa-epbx and epoetin alfa, which had mean treatment durations of 18.1 and 17.7 weeks, respectively. Incidences of treatment-emergent AEs, serious AEs, and discontinuation of study drug treatment because of treatment-emergent AEs were 86.5%, 39.4%, and 6.6%, respectively, for the combined long-term safety studies group, which had a mean treatment duration of 40.0 weeks. In total, 12 patients across the combined randomized groups (epoetin alfa-epbx, n = 5; epoetin alfa, n = 7) and 9 patients in the combined long-term safety studies group tested anti-recombinant human erythropoietin antibody positive in 1 or more visits during study conduct. No patient in any group developed neutralizing antibodies or pure red blood cell aplasia.

Limitations

Epoetin alfa comparator not included in the long-term safety studies, greater cumulative exposure to study drug for epoetin alfa-epbx, shorter follow-up in the randomized studies, and potential for selection bias among patients in the open-label long-term safety studies.

Conclusions

This analysis reinforces previous conclusions of similar safety profiles between epoetin alfa-epbx and epoetin alfa. Furthermore, epoetin alfa-epbx had no unexpected safety signals during long-term treatment.

Funding

This study was funded by Hospira Inc, which was acquired by Pfizer Inc in September 2015.

Trial Registration

ClinicalTrials.gov EPOE-10-13 (NCT01473420); EPOE-10-01 (NCT01473407); EPOE-11-04 (NCT01628120); EPOE-11-03 (NCT01628107).

Antibody-mediated pure red cell aplasia related with epoetin-beta pegol (C.E.R.A.) as an erythropoietic agent: case report of a dialysis patient

BACKGROUND

Erythropoietin-stimulating agents (ESAs) are used to treat anemia in patients with chronic kidney disease, enabling maintenance of stable hemoglobin levels and eliminating the need for multiple transfusions. Epoetin-beta pegol (C.E.R.A.) is a continuous erythropoietin receptor activator created by integrating a large methoxy-polyethylene-glycol-polymer chain into the erythropoietin molecule, which provides it with a longer half-life. On rare occasions, cases of antibody-mediated pure red cell aplasia (PRCA) related to ESAs are reported. They are characterized by abrupt onset of severe transfusion-dependent anemia, despite ESA therapy. We herein report a case of antibody-mediated PRCA in a dialysis patient receiving C.E.R.A.

CASE PRESENTATION

A 44-year-old man with end-stage renal failure had been receiving continuous ambulatory peritoneal dialysis for 2 years. C.E.R.A. was administered subcutaneously as a sole ESA once a month at the hospital since 4 years ago for the treatment of renal anemia and his hemoglobin level was well controlled at 12 g/dl. From 10 months before diagnosis, however, his hemoglobin level suddenly declined, necessitating frequent transfusions. Based on the results of a bone marrow examination and detection of anti-C.E.R.A. antibodies, the patient was diagnosed with antibody-mediated PRCA. After successful elimination of the antibodies using oral prednisolone plus cyclosporine, the patient was re-administrated C.E.R.A. intravenously, as there are few reports of antibody-mediated PRCA related to ESA using that administration route. He responded to the C.E.R.A., and his anemia dramatically improved, eliminating the need for blood transfusions.

CONCLUSIONS

This is the first reported case of recovery from an antibody-mediated PRCA with C.E.R.A. after its re-administration following a reversal of the antibody. It has been suggested that the additional large pegylation chain makes C.E.R.A. less likely to trigger antibody generation than other ESAs. Following successful treatment of antibody-mediated PRCA using immunosuppressive therapy, C.E.R.A. can be re-administered intravenously to treat renal anemia.

T-Cell Dependent Immunogenicity of Protein Therapeutics Pre-clinical Assessment and Mitigation-Updated Consensus and Review 2020

Immune responses to protein and peptide drugs can alter or reduce their efficacy and may be associated with adverse effects. While anti-drug antibodies (ADA) are a standard clinical measure of protein therapeutic immunogenicity, T cell epitopes in the primary sequences of these drugs are the key drivers or modulators of ADA response, depending on the type of T cell response that is stimulated (e.g., T helper or Regulatory T cells, respectively). In a previous publication on T cell-dependent immunogenicity of biotherapeutics, we addressed mitigation efforts such as identifying and reducing the presence of T cell epitopes or T cell response to protein therapeutics prior to further development of the protein therapeutic for clinical use. Over the past 5 years, greater insight into the role of regulatory T cell epitopes and the conservation of T cell epitopes with self (beyond germline) has improved the preclinical assessment of immunogenic potential. In addition, impurities contained in therapeutic drug formulations such as host cell proteins have also attracted attention and become the focus of novel risk assessment methods. Target effects have come into focus, given the emergence of protein and peptide drugs that target immune receptors in immuno-oncology applications. Lastly, new modalities are entering the clinic, leading to the need to revise certain aspects of the preclinical immunogenicity assessment pathway. In addition to drugs that have multiple antibody-derived domains or non-antibody scaffolds, therapeutic drugs may now be introduced via viral vectors, cell-based constructs, or nucleic acid based therapeutics that may, in addition to delivering drug, also prime the immune system, driving immune response to the delivery vehicle as well as the encoded therapeutic, adding to the complexity of assessing immunogenicity risk. While it is challenging to keep pace with emerging methods for the preclinical assessment of protein therapeutics and new biologic therapeutic modalities, this collective compendium provides a guide to current best practices and new concepts in the field.

Economic Benefits of Switching From Intravenous to Subcutaneous Epoetin Alfa for the Management of Anemia in Hemodialysis Patients

Background:

Erythropoiesis-stimulating agents including epoetin alfa have been a mainstay of anemia management in patients with chronic kidney disease. Although the standard practice has been to administer epoetin alfa to patients on hemodialysis (HD) intravenously (IV), subcutaneous (SQ) epoetin alfa is longer acting and achieve the same target hemoglobin level to be maintained at a reduced dose and cost.

Objective:

The primary objective of this study was to determine the economic benefits of change in route of epoetin alfa administration from IV to SQ in HD patients. The secondary objectives were (1) to determine the differences in epoetin alfa doses at the pre-switch (IV) and post-switch period (SQ) and (2) to determine serum hemoglobin concentration, transferrin saturation, ferritin level, IV iron dose and cost in relationship to route of epoetin alfa administration.

Design:

This retrospective observational study included patients who transitioned from IV to SQ epoetin alfa.

Setting:

Two HD sites in southern Saskatchewan (Regina General Hospital, and Wascana Dialysis Unit, Regina) and 2 sites in northern Saskatchewan (St. Paul’s [SPH] Hospital, and SPH Community Renal Health Center, Saskatoon).

Patients:

The study includes 215 patients who transitioned from IV to SQ and were alive at the end of 12-month follow-up period.

Measurements:

We calculated the dose and cost of different routes of epoetin alfa administration/patient month. Also, serum hemoglobin, markers of iron stores (transferrin saturation and ferritin), IV iron dose, and cost were determined in relation to route of epoetin alfa administration.

Methods:

Data were gathered from 6 months prior (IV) to 12 months after switching treatment to SQ. The paired t-test and Wilcoxon signed-rank test were used to compare variables between pre-switch (IV) and post-switch (SQ) period.

Results:

The median cost (interquartile range) of epoetin alfa/patient-month decreased from (CAD508.3 [CAD349-CAD900.8]) pre-switch (IV) to (CAD381.2 [CAD247-CAD681]) post-switch (SQ) (P < .001), a decrease of 25%. The median epoetin alfa dose/patient-month reduced from (38 500 [25 714.3-64 166.5] international unit) pre-switch to (26 750.3 [17 362.6-48 066] IU) post-switch (P < .001), a decrease of 30.51%. The mean hemoglobin concentration (± standard deviation) for patients in both periods remained stable (103.3 ± 9.2 vs 104.3 ± 13.3 g/L, P = .34) and within the target range. There were no significant differences in transferrin saturation, ferritin, and IV iron dose and cost between the 2 study periods.

Limitations:

We were unable to consistently obtain information across all the sites on hospitalizations, inflammatory markers, nutritional status, and gastrointestinal bleeding. In addition, as our study sample was subject to survival bias, we cannot generalize our study results to other populations.

Conclusions:

We have shown that administering epoetin alfa SQ in HD patients led to a 30.51% reduction in dose and 25% reduction in cost while achieving equivalent hemoglobin levels. Given the cost sparing advantages without compromising care while achieving comparable hemoglobin levels, HD units should consider converting to SQ mode of administration.

Trial registration:

The study was not registered on a publicly accessible registry as it was a retrospective chart review and exempted from review by the Research Ethics Board of the former Regina Qu’Appelle Health Region.

Development of ImmTOR Tolerogenic Nanoparticles for the Mitigation of Anti-drug Antibodies

The development of anti-drug antibodies (ADAs) is a common cause for treatment failure and hypersensitivity reactions for many biologics. The focus of this review is the development of ImmTOR, a platform technology designed to prevent the formation of ADAs that can be applied broadly across a wide variety of biologics by inducing immunological tolerance with ImmTOR nanoparticles encapsulating rapamycin. The induction of tolerance is antigen-specific and dependent on the incorporation of rapamycin in nanoparticles and the presence of the antigen at the time of administration of ImmTOR. Evidence for the induction of specific immune tolerance vs. general immune suppression is supported by the findings that: (1) ImmTOR induces regulatory T cells specific to the co-administered antigen; (2) tolerance can be transferred by adoptive transfer of splenocytes from treated animals to naïve recipients; (3) the tolerance is durable to subsequent challenge with antigen alone; and (4) animals tolerized to a specific antigen are capable of responding to an unrelated antigen. ImmTOR nanoparticles can be added to new or existing biologics without the need to modify or reformulate the biologic drug. The ability of ImmTOR to mitigate the formation of ADAs has been demonstrated for coagulation factor VIII in a mouse model of hemophilia A, an anti-TNFα monoclonal antibody in a mouse model of inflammatory arthritis, pegylated uricase in hyperuricemic mice and in non-human primates, acid alpha-glucosidase in a mouse model of Pompe disease, recombinant immunotoxin in a mouse model of mesothelioma, and adeno-associated vectors in a model of repeat dosing of gene therapy vectors in mice and in non-human primates. Human proof-of concept for the mitigation of ADAs has been demonstrated with SEL-212, a combination product consisting of ImmTOR + pegadricase, a highly immunogenic enzyme therapy for the treatment of gout. ImmTOR represents a promising approach to preventing the formation of ADAs to a broad range of biologic drugs.

The immunogenicity of an anti-EGFR single domain antibody (VHH) is enhanced by misfolded amorphous aggregation but not by heat-induced aggregation

Amorphous aggregates of therapeutic proteins can provoke an unwanted immune response (anti-drug antibodies; ADAs), but counter-examples have led to some controversy. Amorphous aggregates can possess unique biophysical and biochemical attributes depending on both the way they are generated and the protein's biophysical/biochemical properties. Here, we examine the immunogenicity of an anti-EGFR single domain antibody (V_HH) in four types of amorphous aggregates: two heat-aggregated V_HH incubated at 65 °C (V_HH-65) and 95 °C (V_HH-95), a misfolded V_HH isolated from the insoluble fraction of the E. coli lysate (V_HH-Ins), and a low solubility misfolded V_HH produced by miss-shuffling the SS bonds of the native V_HH (V_HH-Mis). Biophysical and biochemical measurements indicated that V_HH was indeed natively folded, monomeric, and β-sheeted; that V_HH-65 was partially unfolded and formed aggregates with a Z-average (Zave) of 771 nm; whereas V_HH-95 was unfolded and formed aggregates of 1722 nm; and that both V_HH-Ins and V_HH-Mis were misfolded with non-native intermolecular SS bonds and formed aggregates with a Zave of 1846 nm and 1951 nm, respectively. The IgG level generated in Jcl:ICR mice determined by ELISA showed that the native V_HH was barely immunogenic, V_HH-95 was not immunogenic, while V_HH-65 was mildly immunogenic. By contrast, the misfolded aggregates, V_HH-Ins and V_HH-Mis, having a Zave and an aggregation propensity similar to that of V_HH-95, were highly immunogenic. These findings indicate the critical role of the biochemical and biophysical attributes of the amorphous aggregates in generating an immune response against a protein, rather than just their sizes.

Harmonization and standardization of immunogenicity assessment of biotherapeutic products

Understanding of the determinants of immunogenicity, the testing paradigm, the impact of antibody attributes on clinical outcomes and regulatory guidance is leading to harmonized practices for immunogenicity assessment of biotherapeutics. However, generation of robust immunogenicity data for inclusion in product labels to support clinical practice continues to be a challenge. Assays, protocols and antibody positive controls/standards need to be developed in sufficient time to allow assessment of clinical immunogenicity using validated methods and optimized protocols. Standardization and harmonization play a significant role in achieving acceptable results. Harmonization in the postapproval setting is crucial for a valid interpretation of the product's immunogenicity and its clinical effects. Efforts are ongoing to standardize assays where possible for antibody measurement and for measuring product/drug levels by producing reference standards. Provision of such standards will help toward personalized treatment strategies with better patient outcomes.

Etiologies and Treatment Burden in Adult Patients with Pure Red Cell Aplasia: A Single-Center Experience and Review of Literature

Background

Pure red cell aplasia (PRCA) is less common blood disorder; the causes and the treatments of PRCA are varied.

Methods

We conducted a retrospective study during January 2010-December 2017, to explore the etiologies and to evaluate the response and treatment burden in adult patients with PRCA.

Results

Of 32 PRCA patients, median age was 57 years (18-90 years). Median hemoglobin level and reticulocyte count at the time of diagnosis were 5.6 g/dL (3.3-7.3 g/dL) and 0.3% (0.1-0.7%), respectively. Median time to hematologic recovery was 12 weeks (3-72 weeks), and median number of red blood cell transfusion (RBC) was 20 units (4-100 units). Causes of PRCA were erythropoiesis-stimulating agent (ESA) (47%), parvovirus B19 infection (19%), thymoma (13%), zidovudine (6%), primary autoimmune PRCA (6%), Kaposi's sarcoma (3%), systemic lupus erythematosus (3%), and ABO-mismatched stem cell transplantation (3%). Only 9 out of 24 treated patients achieved hematologic response within 8 weeks of treatment. Intravenous immunoglobulin therapy provided 100% response rate in patients with parvovirus B19-associated PRCA and primary autoimmune PRCA. Low response rate was found in patients receiving immunosuppressants and chemotherapy for the treatment of ESA and thymoma-associated PRCA, respectively.

Conclusions

Treatment outcome of PRCA depended upon the causes and the types of treatment, and the burden of RBC transfusion was very high in patients with ESA and thymoma-associated PRCA.

Established and Emerging Immunological Complications of Biological Therapeutics in Multiple Sclerosis

Biologic immunotherapies have transformed the treatment landscape of multiple sclerosis. Such therapies include recombinant proteins (interferon beta), as well as monoclonal antibodies (natalizumab, alemtuzumab, daclizumab, rituximab and ocrelizumab). Monoclonal antibodies show particular efficacy in the treatment of the inflammatory phase of multiple sclerosis. However, the immunological perturbations caused by biologic therapies are associated with significant immunological adverse reactions. These include development of neutralising immunogenicity, secondary immunodeficiency and secondary autoimmunity. These complications can affect the balance of risks and benefits of biologic agents, and 2018 saw the withdrawal from the market of daclizumab, an anti-CD25 monoclonal antibody, due to concerns about the development of severe, unpredictable autoimmunity. Here we review established and emerging risks associated with multiple sclerosis biologic agents, with an emphasis on their immunological adverse effects. We also discuss the specific challenges that multiple sclerosis biologics pose to drug safety systems, and the potential for improvements in safety frameworks.

Immunogenicity of TNF-Inhibitors

Tumor necrosis factor inhibitors (TNFi) have significantly improved treatment outcome of rheumatic diseases since their incorporation into treatment protocols two decades ago. Nevertheless, a substantial fraction of patients experiences either primary or secondary failure to TNFi due to ineffectiveness of the drug or adverse reactions. Secondary failure and adverse events can be related to the development of anti-drug antibodies (ADA). The earliest studies that reported ADA toward TNFi mainly used drug-sensitive assays. Retrospectively, we recognize this has led to an underestimation of the amount of ADA produced due to drug interference. Drug-tolerant ADA assays also detect ADA in the presence of drug, which has contributed to the currently reported higher incidence of ADA development. Comprehension and awareness of the assay format used for ADA detection is thus essential to interpret ADA measurements correctly. In addition, a concurrent drug level measurement is informative as it may provide insight in the extent of underestimation of ADA levels and improves understanding the clinical consequences of ADA formation. The clinical effects are dependent on the ratio between the amount of drug that is neutralized by ADA and the amount of unbound drug. Pharmacokinetic modeling might be useful in this context. The ADA response generally gives rise to high affinity IgG antibodies, but this response will differ between patients. Some patients will not reach the phase of affinity maturation while others generate an enduring high titer high affinity IgG response. This response can be transient in some patients, indicating a mechanism of tolerance induction or B-cell anergy. In this review several different aspects of the ADA response toward TNFi will be discussed. It will highlight the ADA assays, characteristics and regulation of the ADA response, impact of immunogenicity on the pharmacokinetics of TNFi, clinical implications of ADA formation, and possible mitigation strategies.