The impact of immunogenicity on therapeutic antibody pharmacokinetics: A preclinical evaluation of the effect of immune complex formation and antibody effector function on clearance

A nanobody-enzyme fusion protein targeting PD-L1 and sialic acid exerts anti-tumor effects by C-type lectin pathway-mediated tumor associated macrophages repolarizing

Aberrant sialylated glycosylation in the tumor microenvironment is a novel immune suppression pathway, which has garnered significant attention as a targetable glycoimmune checkpoint for cancer immunotherapy to address the dilemma of existing therapies. However, rational drug design and in-depth mechanistic studies are urgently required for tumor sialic acid to become valuable glycoimmune targets. In this study, we explored the positive correlation of PD-L1 and sialyltransferase expression in clinical colorectal cancer tissues and identified their mutual regulation effects in macrophages. Subsequently, we characterized a new sialidase with excellent properties from human oral symbiotic bacteria and then developed a novel nanobody-enzyme fusion protein, designated as Nb16-Sia, to concurrently target the PD-L1 and sialic acid. Results from syngeneic colon tumor models reveal superior efficacy of Nb16-Sia over monotherapy and combinations, which could remodel the tumor immune microenvironment. Mechanistically, Nb16-Sia, which could repolarize macrophages from the tumor-promoting M2 to anti-tumor M1 phenotype via the C-type lectin pathway, exerted its antitumor efficacy mainly by regulating tumor-associated macrophages. Our strategy of nanobody-enzyme fusion protein effectively enables the delivery of sialidase, allows the collaboration between anti-PD-L1 nanobody and sialidase in combating tumors, and holds considerable promise for further development.

Comprehensive evaluation of anti-emicizumab antibodies in acquired hemophilia A: a detailed case study and methodological evaluation

BACKGROUND

Acquired hemophilia A (AHA) is a rare and severe bleeding disorder characterized by autoantibodies inhibiting coagulation factor (F)VIII. Current treatment of AHA involves bypassing agents or FVIII replacement therapy, yet their efficacy is limited in cases of high inhibitor titers. Emicizumab, a humanized bispecific monoclonal antibody, has shown promising hemostatic effectiveness in persons with congenital hemophilia A (HA) and AHA, but a minority of patients developed anti-drug antibodies (ADAs), compromising its efficacy.

OBJECTIVES

This study aims to characterize the development and impact of anti-emicizumab antibodies in a patient with acquired hemophilia A (AHA) who experienced reduced efficacy of emicizumab treatment.

METHODS

We present a comprehensive characterization of anti-emicizumab antibodies in a patient with AHA experiencing diminished emicizumab efficacy from week 10 of treatment. We developed a method for analysis of anti-emicizumab antibodies, distinguishing immunoglobulin (Ig) subclasses and IgG subtype profiling. ADAs' neutralizing activity was evaluated using a modified clotting assay.

RESULTS

The Luminex-based assay demonstrated the presence of anti-emicizumab antibodies, confirmed through competitive analysis. We detected anti-emicizumab IgG antibodies in the patient's plasma between week 16 and 29. IgG1 and IgG2 subclasses were identified. Longitudinal analysis showed IgG isotype antibodies against both emicizumab and FVIII. Anti-emicizumab antibodies exhibited noninhibitory activity, confirmed by a modified Bethesda assay. Moreover, no accelerated clearance of emicizumab was observed in plasma samples from the patient.

CONCLUSION

This study presents the first documented case of anti-emicizumab antibodies in AHA. Our study provides insights into ADA development against emicizumab, emphasizing the need for monitoring tools. The developed method enables comprehensive evaluation of ADAs, aiding in personalized treatment strategies. These findings contribute to understanding emicizumab's immunogenicity profile in AHA, facilitating its optimized clinical use.

Therapeutic drug monitoring and immunogenetic factors associated with the use of adalimumab in Crohn's disease patients

Crohn's disease (CD) involves immune system interactions with intestinal tissue, driven by pro-inflammatory cytokines like Tumor Necrosis Factor (TNF-α). Adalimumab, targeting TNF-α, regulates associated inflammatory responses. Despite being humanized, it may induce immunogenic processes, affecting treatment effectiveness. Thus, monitoring serum adalimumab and anti-drug antibody (ADA) levels can optimize therapy. Understanding genetic factors influencing adalimumab response can enhance personalized treatment and improve patient quality of life. We aimed to quantify adalimumab serum levels, assess test interchangeability, detect ADA, examine immune complex formation, and investigate genetic phenotypes related to immunogenicity in CD patients. Seventy CD patients in the maintenance phase with adalimumab were classified into active (CDA) and remission (CDR) groups. Adalimumab concentration was determined via enzyme-linked immunosorbent assay (ELISA-Promonitor) and lateral flow assay (Quantum Blue), with assay interchangeability assessed statistically. ADA and immune complex formation were quantified using ELISA assays. DNA was genotyped for the genes ATG16L1, CD96, and CD155. No significant differences in adalimumab serum concentrations were observed between groups, regardless of the assay. However, a statistical difference between the tests indicated measurement disparity (P = 0.003), with moderate agreement (Lin's correlation of 0.247). ADA was detected in 4 of 27 of the patients with infratherapeutic levels, 3 in the CDA group and 1 in the CDR group. Analysis of immune complexes revealed significantly higher concentrations in the CDA group (P = 0.0125). The genotypic evaluation revealed significant associations for the CD96 CC (wild-type) genotype with higher CRP levels, colonic involvement, and infratherapeutic levels of adalimumab. ATG16L1 CC genotype was associated with higher CDEIS and fecal calprotectin values, while the variant (TT) genotype had lower platelet counts. The effectiveness of treatment with adalimumab was not directly related to higher medication levels in this cohort. The disparity between tests indicates the need to use only one test in patient follow-up to ensure accuracy in therapeutic monitoring. Genotypic differences highlight the correlation between the wild genotype for CD96 and ATG16L1 with unfavorable laboratory and endoscopic response to adalimumab. Finally, the more significant levels of immune complexes in the CDA group indicate an association with a worse response to adalimumab.

Engineering a Low-Immunogenic Mirror-Image VHH against Vascular Endothelial Growth Factor

Immunogenicity is a major caveat of protein therapeutics. In particular, the long-term administration of protein therapeutic agents leads to the generation of antidrug antibodies (ADAs), which reduce drug efficacy while eliciting adverse events. One promising solution to this issue is the use of mirror-image proteins consisting of d-amino acids, which are resistant to proteolytic degradation in immune cells. We have recently reported the chemical synthesis of the enantiomeric form of the variable domain of the antibody heavy chain (d-VHH). However, identifying mirror-image antibodies capable of binding to natural ligands remains challenging. In this study, we developed a novel screening platform to identify a d-VHH specific for vascular endothelial growth factor A (VEGF-A). We performed mirror-image screening of two newly constructed synthetic VHH libraries displayed on T7 phage and identified VHH sequences that effectively bound to the mirror-image VEGF-A target (d-VEGF-A). We subsequently synthesized a d-VHH candidate that preferentially bound the native VEGF-A (l-VEGF-A) with submicromolar affinity. Furthermore, immunization studies in mice demonstrated that this d-VHH elicited no ADAs, unlike its corresponding l-VHH. Our findings highlight the utility of this novel d-VHH screening platform in the development of protein therapeutics exhibiting both reduced immunogenicity and improved efficacy.

Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure

Introduction

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.

Methods

TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).

Results

Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.

Discussion

This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

Biodistribution of Drug/ADA Complexes: The Impact of Immune Complex Formation on Antibody Distribution

The clinical use of therapeutic monoclonal antibodies (mAbs) for the treatment of cancer, inflammation, and other indications has been successfully established. A critical aspect of drug-antibody pharmacokinetics is immunogenicity, which triggers an immune response via an anti-drug antibody (ADA) and forms drug/ADA immune complexes (ICs). As a consequence, there may be a reduced efficacy upon neutralization by ADA or an accelerated drug clearance. It is therefore important to understand immunogenicity in biological therapies. A drug-like immunoglobulin G (IgG) was radiolabeled with tritium, and ICs were formed using polyclonal ADA, directed against the complementary-determining region of the drug-IgG, to investigate in vivo biodistribution in rodents. It was demonstrated that 65% of the radioactive IC dose was excreted within the first 24 h, compared with only 6% in the control group who received non-complexed 3H-drug. Autoradiographic imaging at the early time point indicated a deposition of immune complexes in the liver, lung, and spleen indicated by an increased radioactivity signal. A biodistribution study confirmed the results and revealed further insights regarding excretion and plasma profiles. It is assumed that the immune complexes are readily taken up by the reticuloendothelial system. The ICs are degraded proteolytically, and the released radioactively labeled amino acids are redistributed throughout the body. These are mainly renally excreted as indicated by urine measurements or incorporated into protein synthesis. These biodistribution studies using tritium-labeled immune complexes described in this article underline the importance of understanding the immunogenicity induced by therapeutic proteins and the resulting influence on biological behavior.

The establishment of B cell-deficient Igh-J KO mouse model by gene editing and efficacy evaluation

Over the last few years, immunotherapy has made significant progress in treating various cancers with therapeutic antibodies. However, therapeutic antibodies have been validated for inducing an unintended immune response in human and animal models, which leads to the emergence of anti-drug antibodies (ADAs) and affects their effectiveness and safety. In preclinical research, ADAs production by B cells may accelerate antibody metabolism and result in missing potential candidate molecules. Thus, it is urgent to develop preclinical models that remove only B cells without affecting the function of T and NK cells. Rearrangement of immunoglobulin heavy chain J gene fragment (Igh-J) is the first link in B cell development, and immunotherapies are currently leaning toward combination treatments with PD-1/PD-L1 antibodies, here we created humanized PD-1, PD-L1 and Igh-J knockout (hPD-1/hPD-L1, Igh-J KO) mice and validated by using the reported high immunogenicity drug M7824 (a protein designed to simultaneously block PD-L1 and TGF-β pathways, poorly anti-tumor efficacy in immunocompetent mice). Phenotypic analysis revealed that human PD-1 and PD-L1 were detectable in hPD-1/hPD-L1, Igh-J KO mice, but not mouse IgM and IgD. Igh-J KO depleted B cells while increased the percentage of other immune cell types. Meanwhile, the humanization of PD-1/PD-L1 and Igh-J KO had neither effect on the overall development, differentiation, or distribution of T cell subtypes, nor on the activation of NK and T cells, indicating that mice can be used for T and NK-related immunotherapies. Furthermore, M7824 treatment of these B cell-deficient mice inhibited tumor growth significantly, with higher M7824 analog concentrations and lower ADA-positive rates. These findings demonstrate that Igh-J KO mice are an effective and stable preclinical model for testing drugs based on T and NK cells with high immunogenicity in vivo.

Pre-Clinical In-Vitro Studies on Parameters Governing Immune Complex Formation

The success of biotherapeutics is often challenged by the undesirable events of immunogenicity in patients, characterized by the formation of anti-drug antibodies (ADA). Under specific conditions, the ADAs recognizing the biotherapeutic can trigger the formation of immune complexes (ICs), followed by cascades of subsequent effects on various cell types. Hereby, the connection between the characteristics of ICs and their downstream impact is still not well understood. Factors governing the formation of ICs and the characteristics of these IC species were assessed systematically in vitro. Classic analytical methodologies such as SEC-MALS and SV-AUC, and the state-of-the-art technology mass photometry were applied for the characterization. The study demonstrates a clear interplay between (1) the absolute concentration of the involved components, (2) their molar ratios, (3) structural features of the biologic, (4) and of its endogenous target. This surrogate study design and the associated analytical tool-box is readily applicable to most biotherapeutics and provides valuable insights into mechanisms of IC formation prior to FIH studies. The applicability is versatile—from the detection of candidates with immunogenicity risks during developability assessment to evaluation of the impact of degraded or post-translationally modified biotherapeutics on the formation of ICs.

2021 White Paper on Recent Issues in Bioanalysis: TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparability & Cut Point Appropriateness (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccine Assays; Immunogenicity of Biotherapeutics and Novel Modalities; Integrated Summary of Immunogenicity Harmonization)

The 15th edition of the Workshop on Recent Issues in Bioanalysis (15th WRIB) was held on 27 September to 1 October 2021. Even with a last-minute move from in-person to virtual, an overwhelmingly high number of nearly 900 professionals representing pharma and biotech companies, contract research organizations (CROs), and multiple regulatory agencies still eagerly convened to actively discuss the most current topics of interest in bioanalysis. The 15th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on biomarker assay development and validation (BAV) (focused on clarifying the confusion created by the increased use of the term "Context of Use - COU"); mass spectrometry of proteins (therapeutic, biomarker and transgene); state-of-the-art cytometry innovation and validation; and, critical reagent and positive control generation were the special features of the 15th edition. This 2021 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2021 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparability & Cut Point Appropriateness. Part 1A (Endogenous Compounds, Small Molecules, Complex Methods, Regulated Mass Spec of Large Molecules, Small Molecule, PoC), Part 1B (Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine) and Part 2 (ISR for Biomarkers, Liquid Biopsies, Spectral Cytometry, Inhalation/Oral & Multispecific Biotherapeutics, Accuracy/LLOQ for Flow Cytometry) are published in volume 14 of Bioanalysis, issues 9 and 10 (2022), respectively.

Enhanced immunogenic potential of cancer immunotherapy antibodies in human IgG1 transgenic mice

ABBREVIATIONS

ADA Anti-Drug Antibodies; BCR B Cell Receptor; BId Idiotype-specific B Cell; BiTE Bispecific T cell Engager; BMC Bone Marrow Chimeric Mice; BSA Bovine Serum Albumin; CDR Complementary Determining Region; CEA Carcinoembryonic Antigen; CIT Cancer Immunotherapy; CitAbs Cancer Immunotherapy Antibodies; DC Dendritic Cell; ELISA Enzyme-Linked Immunosorbent Assay; FcRn Neonatal Fc Receptor; FcyR Fc gamma Receptor; GM-CSF Granulocyte-Macrophage Colony Stimulating Factor; gMFI Geometric Mean Fluorescence Intensity; H Heavy Chain; IC Immune Complex; Id Idiotype; IgA Immunoglobulin alpha; IgG1 Immunoglobulin gamma 1; IL-2 Interleukin 2; IL-2R Interleukin 2 Receptor; IL2v Interleukin 2 Variant; IVIG1 Intravenous Immunoglobulin 1; KLH Keyhole Limpet Hemocyanin; L Light Chain; MAPPs MHC-associated Peptide Proteomics; MHC Major Histocompatibility Complex; PBMC Peripheral Blood Mononuclear Cells; PBS Phosphate Buffered Saline; SHM Somatic Hypermutation; scFv Single-chain Variable Fragment; TCR T cell Receptor; TFc Fc-specific T cell; TId Id-specific T cell; UV Ultraviolet; V Variable.