Monitoring antigen-specific cellular immune response using an RT-ddPCR-based assay for IFN-γ gene expression.

This study evaluated the effectiveness of the Reverse Transcription-droplet digital PCR (RT-ddPCR) method in measuring T-cell-mediated immunity by quantifying IFN-γ mRNA expression. The results demonstrated that peak IFN-γ expression occurred approximately 4 h after stimulation of whole blood and peripheral blood mononuclear cells (PBMCs) by stimulants. The fold activation of IFN-γ mRNA expression in 100 µL of blood challenged with CEF peptides was lower than that observed in PBMCs.

Industry Perspective on First-in-Human and Clinical Pharmacology Strategies to Support Clinical Development of T-Cell Engaging Bispecific Antibodies for Cancer Therapy.

T-cell-engaging bispecific antibodies (TCEs) that target tumor antigens and T cells have shown great promise in treating cancer, particularly in hematological indications. The clinical development of TCEs often involves a lengthy first-in-human (FIH) trial with many dose-escalation cohorts leading up to an early proof of concept (POC), enabling either a no-go decision or dose selection for further clinical development. Multiple factors related to the target, product, disease, and patient population influence the efficacy and safety of TCEs.

Determining the Degree of Sulfo-tag Conjugation to AAV5 Vectors by LC-HRMS and Evaluating the Effects on Antibody Binding Affinity and Bridging Assay Sensitivity.

Pre-existing anti-AAV antibodies can be detected using ligand binding-based assay formats. One such format is the MSD-based bridging assay, which uses sulfo-tag-labeled AAV vectors as detection reagents. However, no method has been developed to accurately measure the degree of sulfo-tag labeling on AAV vectors.

Immunogenicity Risk Assessment of Process-Related Impurities in An Engineered T Cell Receptor Cellular Product.

Cell therapies such as genetically modified T cells have emerged as a promising and viable treatment for hematologic cancers and are being aggressively pursued for a wide range of diseases and conditions that were previously difficult to treat or had no cure. The process development requires genetic modifications to T cells to express a receptor (engineered T cell receptor (eTCR)) of specific binding qualities to the desired target. Protein reagents utilized during the cell therapy manufacturing process, to facilitate these genetic modifications, are often present as process-related impurities at residual levels in the final drug product and can represent a potential immunogenicity risk upon infusion.

A High Threshold of Biotherapeutic Aggregate Numbers is Needed to Induce an Immunogenic Response In Vitro, In Vivo, and in the Clinic.

Background And Purpose: There is concern that subvisible aggregates in biotherapeutic drug products pose a risk to patient safety. We investigated the threshold of biotherapeutic aggregates needed to induce immunogenic responses.

Methods And Results: Highly aggregated samples were tested in cell-based assays and induced cellular responses in a manner that depended on the number of particles.

Preexisting antibody assays for gene therapy: Considerations on patient selection cutoffs and companion diagnostic requirements.

Recombinant adeno-associated virus (AAV) vectors are the leading delivery vehicle used for gene therapies. Anti-AAV antibodies (AAV Abs) can interact with the viral capsid component of an AAV-based gene therapy (GT). Therefore, patients with preexisting AAV Abs (seropositive patients) are often excluded from GT trials to prevent treatment of patients who are unlikely to benefit or may have a higher risk for adverse events outweighing treatment benefits.

An IQ Consortium Perspective on Best Practices for Bioanalytical and Immunogenicity Assessment Aspects of CAR-T and TCR-T Cellular Therapies Development.

CAR-T therapies have shown remarkable efficacy against hematological malignancies in the clinic over the last decade and new studies indicate that progress is being made to use these novel therapies to target solid tumors as well as treat autoimmune disease. Innovation in the field, including TCR-T, allogeneic or "off the shelf" CAR-T, and autoantigen/armored CAR-Ts are likely to increase the efficacy and applications of these therapies. The unique aspects of these cell-based therapeutics; patient-derived cells, intracellular expression, in vivo expansion, and phenotypic changes provide unique bioanalytical challenges to develop pharmacokinetic and immunogenicity assessments.

2022 White Paper on Recent Issues in Bioanalysis: FDA Draft Guidance on Immunogenicity Information in Prescription Drug Labeling, LNP & Viral Vectors Therapeutics/Vaccines Immunogenicity, Prolongation Effect, ADA Affinity, Risk-based Approaches, NGS, qPCR, ddPCR Assays ( - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Immunogenicity & Risk Assessment of Biotherapeutics and Novel Modalities; NAb Assays Integrated Approach).

The 2022 16th Workshop on Recent Issues in Bioanalysis (WRIB) took place in Atlanta, GA, USA on September 26-30, 2022. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 16th 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.

PK/PD and Bioanalytical Considerations of AAV-Based Gene Therapies: an IQ Consortium Industry Position Paper.

Interest and efforts to use recombinant adeno-associated viruses (AAV) as gene therapy delivery tools to treat disease have grown exponentially. However, gaps in understanding of the pharmacokinetics/pharmacodynamics (PK/PD) and disposition of this modality exist. This position paper comes from the Novel Modalities Working Group (WG), part of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ).

Bioanalytical Methods for Characterization of CAR-T Cellular Kinetics: Comparison of PCR Assays and Matrices.

Recently, multiple chimeric antigen receptor T-cell (CAR-T)-based therapies have been approved for treating hematological malignancies, targeting CD19 and B-cell maturation antigen. Unlike protein or antibody therapies, CAR-T therapies are "living cell" therapies whose pharmacokinetics are characterized by expansion, distribution, contraction, and persistence. Therefore, this unique modality requires a different approach for quantitation compared with conventional ligand binding assays implemented for most biologics.

Best Practices and Considerations for Clinical Pharmacology and Pharmacometric Aspects for Optimal Development of CAR-T and TCR-T Cell Therapies: An Industry Perspective.

With the promise of a potentially "single dose curative" paradigm, CAR-T cell therapies have brought a paradigm shift in the treatment and management of hematological malignancies. Both CAR-T and TCR-T cell therapies have also made great progress toward the successful treatment of solid tumor indications. The field is rapidly evolving with recent advancements including the clinical development of "off-the-shelf" allogeneic CAR-T therapies that can overcome the long and difficult "vein-to-vein" wait time seen with autologous CAR-T therapies.

Understanding preclinical and clinical immunogenicity risks in novel biotherapeutics development.

Immunogenicity continues to pose a challenge in the development of biotherapeutics like conventional therapeutic-proteins and monoclonal antibodies as well as emerging modalities such as gene-therapy components, gene editing, and CAR T cells. The approval of any therapeutic is based on a benefit-risk evaluation. Most biotherapeutics address serious medical conditions where the standard of care has a poor outcome.

Evaluation of Cellular Immune Response to Adeno-Associated Virus-Based Gene Therapy.

The number of approved or investigational late phase viral vector gene therapies (GTx) has been rapidly growing. The adeno-associated virus vector (AAV) technology continues to be the most used GTx platform of choice. The presence of pre-existing anti-AAV immunity has been firmly established and is broadly viewed as a potential deterrent for successful AAV transduction with a possibility of negative impact on clinical efficacy and a connection to adverse events.

Comparison of Pre-existing Anti-AAV8 Total Antibody Screening and Confirmatory Assays with a Cell-Based Neutralizing Assay in Normal Human Serum.

Pre-existing adeno-associated viruses (AAV) neutralizing antibodies (NAb) can prevent AAV vectors from transducing target tissues. The immune responses can include binding/total antibodies (TAb) and neutralizing antibodies (NAb). This study is aimed at comparing total antibody assay (TAb) and cell-based NAb assay against AAV8 to help inform the best assay format for patient exclusion criteria.

An Overview of Current Accomplishments and Gaps of COVID-19 Vaccine Platforms and Considerations for Next Generation Vaccines.

Vaccines against SARS-CoV-2 have transformed the course of the COVID-19 pandemic with more than 30 authorizations. More than 2 billion people have been vaccinated with these vaccines developed on very different manufacturing platforms. We have reviewed the unprecedented work done in various aspects of the authorized vaccines and listed three potential improvements: 1) long-term stability at room-temperature conditions; 2) suitability for diverse populations such as infants, elderly, immune-compromised, and those with pre-existing or ongoing diseases; and 3) ability to act against different strains.

Immunogenicity assessment of AAV-based gene therapies: An IQ consortium industry white paper.

Immunogenicity has imposed a challenge to efficacy and safety evaluation of adeno-associated virus (AAV) vector-based gene therapies. Mild to severe adverse events observed in clinical development have been implicated with host immune responses against AAV gene therapies, resulting in comprehensive evaluation of immunogenicity during nonclinical and clinical studies mandated by health authorities. Immunogenicity of AAV gene therapies is complex due to the number of risk factors associated with product components and pre-existing immunity in human subjects.

Immunogenicity Risk Assessment of Spontaneously Occurring Therapeutic Monoclonal Antibody Aggregates.

Aggregates of therapeutic proteins have been associated with increased immunogenicity in pre-clinical models as well as in human patients. Recent studies to understand aggregates and their immunogenicity risks use artificial stress methods to induce high levels of aggregation. These methods may be less biologically relevant in terms of their quantity than those that occur spontaneously during processing and storage.

Comparison of Titer and Signal to Noise (S/N) for Determination of Anti-drug Antibody Magnitude Using Clinical Data from an Industry Consortium.

During biotherapeutic drug development, immunogenicity is evaluated by measuring anti-drug antibodies (ADAs). The presence and magnitude of ADA responses is assessed using a multi-tier workflow where samples are screened, confirmed, and titered. Recent reports suggest that the assay signal to noise ratio (S/N) obtained during the screening tier correlates well with titer.

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 ( - 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.

When to Extend Monitoring of Anti-drug Antibodies for High-risk Biotherapeutics in Clinical Trials: an Opinion from the European Immunogenicity Platform.

The determination of a tailored anti-drug antibody (ADA) testing strategy is based on the immunogenicity risk assessment to allow a correlation of ADAs with changes to pharmacokinetics, efficacy, and safety. The clinical impact of ADA formation refines the immunogenicity risk assessment and defines appropriate risk mitigation strategies. Health agencies request for high-risk biotherapeutics to extend ADA monitoring for patients that developed an ADA response to the drug until ADAs return to baseline levels.

Holistic analytical characterization and risk assessment of residual host cell protein impurities in an active pharmaceutical ingredient synthesized by biocatalysts.

Host cell proteins (HCPs) are a significant class of process-related impurities commonly associated with the manufacturing of biopharmaceuticals. However, due to the increased use of crude enzymes as biocatalysts for modern organic synthesis, HCPs can also be introduced as a new class of impurities in chemical drugs. In both cases, residual HCPs need to be adequately controlled to ensure product purity, quality, and patient safety.

Use of In Vitro Human Skin Models to Assess Potential Immune Activation In Response to Biotherapeutic Attributes and Process-related Impurities.

Subcutaneous (SubQ) injection is a common administration route for biotherapeutics. However, limited tools are available for understanding the dynamic relationships between drug products and resident cells following injection. Advances in tissue engineering have enabled the production of in vitro skin models that recapitulate the morphological structure and functional activity of human skin.

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.