Anti-Drug Antibodies in biopharma development
Antiโdrug antibodies (ADAs) can affect the safety, efficacy, and pharmacokinetics of therapeutic products.
Mercodia offers sensitive, regulatoryโaligned ADA assay development and sample analysis services to support immunogenicity assessment across preclinical and clinical development of biologics, peptides, and nucleotideโbased therapeutics.
understanding antiโdrug antibodies
Therapeutic products may trigger unwanted immune responses that lead to ADA formation. The most common clinical consequence is reduced drug efficacy, where ADAs increase drug clearance or neutralize biological activity. In some cases, ADAs can contribute to serious immuneโmediated adverse events. In other situations, ADA formation may have no measurable clinical impact. ADA assessment is an essential component of development programs to support patient safety and program success.
Clinical impact of ADAs
ADA assays detect antibodies generated in response to the administered therapeutic and assess whether these responses may influence drug exposure, PK/PD relationships, efficacy, or safety. Integrating ADA results with PK and PD data enables informed decisions on dose selection, patient management, and risk mitigation strategies.
The tiered immunogenicity workflow
ADA evaluation typically follows a multiโtier workflow consisting of screening, confirmation, titer determination and, when needed, neutralizing antibody assessment. This structure supports sensitive detection and clear characterization of immune responses.
Screening Assay
Identifies samples that may contain ADA using ligandโbinding assay formats such as bridging ELISA or electrochemiluminescent assays. A statistical cutโpoint distinguishes negative from presumptive positives.
Confirmatory Assay
Verifies drugโspecific binding by competitive inhibition using excess unlabeled drug. A reduced assay signal confirms ADA specificity.
Titer Determination
Provides a semiโquantitative estimate of ADA levels by determining the highest dilution above the assay cutโpoint.
Neutralizing antibody (NAb) assessment
Evaluates whether ADAs interfere with therapeutic activity using functional cellโbased or competitive ligandโbinding formats.
Understanding ADA measurements
ADA assays do not determine absolute antibody concentrations. Instead, ADA assessment relies on qualitative and semiโquantitative strategies consistent with current regulatory expectations. This approach is different from PK, PD, or biomarker assays, which typically provide quantitative metrics.
ADA analysis relies on:
- Tiered testing workflows, used to efficiently identify and confirm true ADAโpositive samples
- Titration (semiโquantitative analysis) to estimate relative antibody levels in confirmed positives
- Lowโthroughput processing in the titer tier due to multiple dilution steps required
This structured approach enables sensitive, specific, and reproducible detection of ADAs and supports reliable immunogenicity risk assessment and regulatoryโcompliant decisionโmaking.
making immunogenicity more efficient
Immunogenicity evaluations can be resourceโintensive. Crossโindustry bioanalytical discussions and peerโreviewed studies highlight pragmatic ways to increase throughput and decision quality when supported by data and fitโforโpurpose validation.
Signalโtoโnoise as an alternative to titer
Titer determination requires multiple serial dilutions, which reduces sample throughput per plate. Several clinical datasets have shown a correlation between signalโtoโnoise (S/N) and ADA titer, and S/Nโbased assessments have, in some cases, demonstrated improved precision and enhanced detection of lowโavidity ADA compared with traditional titer analysis.
When the confirmation step may be omitted
Screening and confirmatory assays are based on the same analytical format and often yield highly consistent results. Extensive data show that applying a more stringent screening cutโoff can allow programs to reach the same conclusions without a separate confirmation step, simplifying workflows while maintaining confidence in the results.
When considering alternative or streamlined ADA strategies, it is important to ensure that the approach is supported by a clear scientific rationale and an understanding of the assayโs performance characteristics. Early engagement with regulatory stakeholders is recommended to confirm that the proposed design is appropriate for the molecule, study phase, and risk profile.
Mercodia supports fitโforโpurpose, riskโbased ADA testing strategies that balance efficiency with data integrity.
the importance of ADA testing in drug development
Antiโdrug antibodies can influence therapeutic performance in multiple ways, affecting drug exposure, pharmacodynamics, safety, and longโterm efficacy. Understanding these effects is essential for interpreting clinical outcomes and guiding dose selection and patient management.
How ADAs can affect therapeutic performance:
- Reduce or neutralize drug activity โ by binding to the therapeutic and preventing target engagement.
- Accelerate or delay drug clearance โ altering exposure and complicating doseโresponse relationships.
- Trigger immuneโrelated adverse events โ depending on molecule and patient factors.
- Interfere with pharmacokinetic (PK) assessments โ making interpretation of concentrationโtime data more difficult.
- Have no observable clinical effect โ in some cases, ADA formation is transient or clinically insignificant.
Why testing matters throughout development
ADA monitoring provides crucial context for interpreting changes in clinical response. By integrating ADA results with PK and PD data, teams can determine whether differences in exposure, efficacy, or safety are driven by immunogenicity or by underlying biology. This supports informed decisions on dosing, study design, patient management, and risk mitigation across development stages.
Our ADA Assay Capabilities
Mercodia provides bioanalytical support for ADA, NAb, PK/PD, and biomarker assessments across preclinical and clinical development. Our laboratory is GLPโapproved and GCPโcompliant, with established expertise in ligandโbinding assay development, validation, and sample analysis for biologics and other large molecule therapeutics.
Our team has extensive experience in designing assays that deliver high sensitivity, reproducibility, and longโterm performance, supporting confident decisionโmaking throughout drug development programs.
Assay Development & Validation
- Customized screening, confirmatory, and titer assay design
- Fitโforโpurpose or fully validated methods in accordance with FDA/EMA guidelines
- Platforms: Ligandโbinding assays (ELISA, MSD) and SPRโbased interaction analysis using Biacoreโข systems.
Preclinical ADA Testing
- Flexible strategies tailored to exploratory or low-risk studies
- Expertise in non-human primate (NHP) to human assay transition
Clinical Sample Analysis
- Highโsensitivity, drug-tolerant ADA assays
- Longitudinal monitoring across clinical phases
- Support from first-in-human (FIH) through Phase III
Our experience
Mercodia has extensive experience supporting ADA testing across preclinical and clinical programs and works with a broad range of therapeutic modalities.
Therapeutic modalities we support:
- Humanized antibody drug candidates
- Nucleotideโbased therapeutics
- Recombinant protein therapies
- Deviceโassociated biologics
Our team brings deep expertise in assay transfer, optimization, and validation, supporting earlyโphase through pivotal clinical studies and ensuring robust performance across study phases.
Frequently Asked Questions
ADAs form when the immune system recognizes a therapeutic protein as foreign. Their occurrence can be influenced by the molecule itself, patientโspecific factors, and the clinical context.
ADAs may neutralize drug activity, accelerate or delay clearance, or interfere with PK assessments. In some cases, they have no measurable clinical effect.
A multiโtier workflow typically includes screening, confirmatory specificity testing, titer determination, and, when relevant, neutralizing antibody assessment.
Alternative strategies, such as using S/N instead of titer or omitting a confirmatory step, may be used when supported by strong assay correlation data, study objectives, and validation evidence.
Have a question?
Whether you are initiating a preclinical study or preparing a pivotal clinical submission, Mercodia provides reliable, regulatoryโcompliant immunogenicity testing services to support your development pathway.
Related Resources
References
Assay signal as an alternative to titer for assessment of magnitude of an antidrug antibody response. Manning et al., Bioanalysis (2017) 9(23), 1849โ1858. https://pubmed.ncbi.nlm.nih.gov/29020795/
Comparison of Titer and Signal to Noise (S/N) for Determination of Antiโdrug Antibody Magnitude Using Clinical Data from an Industry Consortium. Manning et al., The AAPS Journal (2022) 24: 81. https://doi.org/10.1208/s12248-022-00728-8
Antiโdrug Antibody Magnitude and Clinical Relevance Using Signal to Noise (S/N): Bococizumab Case Study. McCush et al., The AAPS Journal (2023) 25:85. https://doi.org/10.1208/s12248-023-00846-x
Correlation of screening and confirmatory results in tiered immunogenicity testing by solution-phase bridging assays. Kubiak et al., Journal of Pharmaceutical and Biomedical Analysis 74 (2013) 235โ245. https://pubmed.ncbi.nlm.nih.gov/23245256/
Confirmatory cut point has limited ability to make accurate classifications in immunogenicity assays. Kubiak et al., Bioanalysis 2020 Feb;12(4):245-256. https://doi.org/10.4155/bio-2019-0283
A strategic approach to nonclinical immunogenicity assessment: a recommendation from the European Bioanalysis Forum. Laurรฉn et al., Bioanalysis 2021 Apr;13(7):537-549. https://pubmed.ncbi.nlm.nih.gov/33729007/
European Bioanalysis Forum recommendation on singlicate analysis for ligand binding assays: time for a new mindset. Barfield et al., Bioanalysis 2020;12(5):273โ84.
GUIDANCE DOCUMENT from FDA: Immunogenicity Testing of Therapeutic Protein Products โ Developing and Validating Assays for Anti-Drug Antibody Detection, 2019. https://www.fda.gov/media/119788/download
GUIDANCE DOCUMENT from EMA: Guideline on Immunogenicity assessment of therapeutic proteins, 2017. https://www.ema.europa.eu/en/documents/scientific-guideline/guideline-immunogenicity-assessment-therapeutic-proteins-revision-1_en.pdf
