From standard toxicity studies and follow-up immune-function testing to immunogenicity assessment, test-system selection, and GLP execution, this article explores how to build an effective immunotoxicity assessment strategy for biotechnology-derived therapeutics.
The expanding diversity of therapeutic modalities, from chemically synthesised small molecules and biotechnology-derived pharmaceuticals to RNA-based products and advanced therapy medicinal products, increasingly requires modality-specific nonclinical safety strategies.
Chemically synthesised small molecule pharmaceuticals are generally developed within the overarching framework described in ICH M3(R2), with potential unintended effects on the immune system considered through the principles of ICH S8. Biotechnology-derived pharmaceuticals, such as monoclonal antibodies and recombinant proteins, are evaluated using the case-by-case principles of ICH S6(R1). Other modalities, including cell and gene therapies, require consideration under their applicable regulatory frameworks and product-specific guidance.
Building a nonclinical testing strategy is, therefore, becoming less about following a predefined checklist and more about asking a fundamental question:
Which test systems will provide the most meaningful information about the potential risks of my particular therapeutic in humans?
This question sits at the centre of an effective immunotoxicity assessment strategy: determining which findings require further investigation and which studies can provide meaningful evidence of immune-related safety risks.
For biotechnologically derived therapeutics, safety assessment should therefore distinguish between intended pharmacology occurring within the expected range, intended effects that are exaggerated or occur at excessive intensity, and unintended or off-target immune effects. These may include unintended immunosuppression or immune activation, exaggerated pharmacology, cytokine release, hypersensitivity, or immunogenicity.
For sponsors outsourcing their nonclinical GLP toxicology program, selecting a CRO that can help address these questions early can have a direct impact on the scientific relevance, interpretability, and efficiency of the resulting safety package.
This is where InnoSer’s GLP study team comes in.
At InnoSer, we work with sponsors from early nonclinical development through GLP execution, helping determine which studies are scientifically relevant, which test systems are appropriate for their therapeutic or chemical, and where additional testing may be justified. As a specialist European preclinical CRO, we partner with sponsors across the DACH region and beyond to deliver defined studies and high-quality safety data within the applicable frameworks, including EMA/FDA and OECD guidelines.
Through our GLP-certified site in Gronau, Germany, formerly Vivo Science (read more about the acquisition performed in August 2026 here), sponsors continue to work directly with the established scientific and technical team, with the site’s GLP-certified capabilities retained within the InnoSer group. Read more about the full scope of GLP capabilities offered by InnoSer here, including OECD-compliant single- and repeated-dose toxicity, as well as medical device testing in full accordance with ISO 10993 guidelines.
This article explores how immunotoxicity and immunogenicity can be assessed, how relevant test systems are selected, and how these considerations can shape a risk-based GLP-compliant immunotoxicity assessment strategy if you are on the path to developing biotechnology-derived therapeutics.
Standard toxicity studies (STS): all new pharmaceuticals must be screened for immunotoxicity indicators in rodents and non-rodents
As per ICH S8 guideline recommendations, the initial evaluation of potential immunotoxicity is typically based on a weight-of-evidence assessment that includes findings from standard repeated-dose toxicity studies. These findings form an important starting point when developing an immunotoxicity assessment strategy for a new pharmaceutical.
At InnoSer, we routinely incorporate the evaluation of immune-related endpoints within GLP toxicity studies to identify early indicators of potential effects on the immune system. For all new human pharmaceuticals, potential immunotoxic effects are generally assessed within the overall nonclinical safety program, including standard repeated-dose toxicity studies conducted in relevant species.
Depending on your therapeutic type and its MoA, as well as previous study findings, we evaluate parameters such as changes in lymphoid organs, haematological findings including the evaluation of leukocyte subsets, inflammatory markers, clinical pathology, histopathology, and other relevant observations.
When standard repeated-dose toxicity studies identify signs of immunotoxicity, we can perform additional functional immune testing to further characterise its significance.
Similarly, depending on the nature of the finding or your drug’s mechanism of action and target population, further immunotoxicity tests may need to be performed, as further described in sections below.
The following example from our study director helps further illustrate how general immune assessment can be complemented by targeted functional studies addressing the sponsor’s specific immune-safety question:
We generally begin by asking what can be assessed within the standard toxicity study (STS), integrating relevant immunotoxicity parameters into the study design, and whether the resulting findings or the therapeutic’s pharmacology warrant further functional investigation. In one GLP immunotoxicity programme, for example, general immune parameters were evaluated first, followed by separate studies investigating cellular and humoral immune responses to a standard antigen and host resistance. It illustrates how functional follow-up studies can be selected to address specific immune-safety questions rather than applying the same predefined assay package to every therapeutic.
Did your standard toxicity study raise immunotoxicity concerns? Functional follow-up assays provide deeper insight into immune-related safety risks
When findings from standard toxicity studies, your therapeutic’s pharmacology or MoA, or other programme-specific considerations indicate a potential immunotoxicity risk, we work with sponsors to determine whether additional immune-function testing is scientifically justified. This step is a key part of an immunotoxicity assessment strategy, helping determine which functional investigations are relevant to the specific safety question.
Rather than applying a predefined testing package, we select follow-up investigations based on the underlying biological question. Depending on the nature of the concern, this may include:
- T-cell Dependent Antibody Response (TDAR)
- Natural Killer (NK) Cell Activity Assays
- Macrophage / Neutrophil Function Assays
- Host Resistance Studies
- Cytokine Release Assays (CRA)
- Lymphocyte Proliferation Assay/ EliSpot assay
In many cases, no single assay provides a complete answer. We frequently combine complementary endpoints to determine whether an observed finding reflects adaptive or innate immune modulation, functional impairment, exaggerated pharmacology or a biologically irrelevant change.
The objective is not to perform every available immunotoxicity assay, but to select the assessments that address the specific safety question posed by the therapeutic.
This risk-based approach is particularly relevant for biotechnology-derived therapeutics, where the mechanism of action itself may involve immune activation, immune suppression or modulation of specific immune pathways.
Selecting the right test system for biotechnology-derived therapeutics as part of your nonclinical toxicology GLP strategy
For biotechnology-derived therapeutics, selecting the right test system is often as important as selecting the right study endpoints. As outlined in ICH S6(R1) a pharmacologically relevant species should not only express the intended target but should demonstrate downstream biological response that adequately reflects the expected human pharmacology.
When conventional laboratory species do not provide sufficient pharmacological relevance, alternative approaches may be required. Indeed, ICH S6(R1) guideline considerations suggest the use of homologous molecules, genetically modified animal models, transgenic models, or relevant human-derived in vitro systems, depending on the therapeutic and scientific question being addressed.
At InnoSer, we bring extensive experience in the selection and application of pharmacologically relevant test systems for biotechnology-derived pharmaceuticals. Our teams have supported programmes involving conventional rodent and non-rodent species, transgenic and genetically modified animal models to help sponsors generate scientifically meaningful and clinically relevant safety data.
Performing immunogenicity and anti-drug antibody (ADA) of novel biotechnology-derived therapeutics as part of your nonclinical toxicology GLP strategy
Another important consideration when assessing biotherapeutics is immunogenicity, the potential for a therapeutic protein to induce an immune response in the host.
In repeated-dose studies, anti-drug antibody (ADA) assessment may be incorporated when warranted, as the development of ADAs can affect systemic exposure, pharmacological activity and the interpretation of toxicity findings.
Depending on the study objectives and the characteristics of the therapeutic, collected samples from nonclinical toxicity studies can undergo further characterization:
- Screening assay: Identifies samples that may contain antibodies capable of binding the therapeutic protein.
- Confirmatory assay: Uses competition with excess unlabelled drug to demonstrate that the detected binding is specifically directed against the therapeutic.
- Characterization assays: Further assess confirmed ADA-positive samples, for example through titration and antibody isotyping.
- Neutralizing antibody (NAb) assay: Determines whether the ADA response functionally interferes with the biological activity of the therapeutic.
Customized ADA assay development for biotechnology-derived therapeutics
The nature of the therapeutic protein can strongly influence the characteristics of the immune response and the performance of the ADA assay.
Anti-drug antibodies may recognize different components of a therapeutic, including the antigen-binding region, Fc region or other structural features such as glycosylated epitopes. Consequently, ADA assays need to be appropriately designed and optimized for the specific therapeutic rather than relying on a one-size-fits-all approach.
Importantly, the development of an ADA response is not inherently adverse. Depending on the therapeutic and its intended mechanism of action, an antibody response may be an expected or desired outcome, as in the case of vaccines, or may represent an unwanted immune response that can affect the safety, efficacy or pharmacokinetics of a therapeutic. The interpretation of ADA therefore needs to consider the intended pharmacology and the magnitude and characteristics of the immune response.
For sponsors, the relevant question is therefore not only whether ADAs are detected, but how immunogenicity findings fit within the wider safety and exposure profile of the therapeutic.
This is reflected in how we have approached previous GLP programmes, as outlined by our study director below:
In one biopharmaceutical GLP programme, repeated-dose toxicity was integrated with toxicokinetic and ADA assessment, with cytokine analysis added to further characterise the immune-related dataset. For complex therapeutics, these endpoints should not be considered in isolation: exposure, immunogenicity, and immune responses can all contribute to interpretation of the safety findings.
At InnoSer, our immunogenicity expertise supports the development, implementation, and optimization of ADA assessment strategies for biotechnology-derived therapeutics. Depending on the study requirements, we can support the development or adaptation of assays for screening, confirmation, and further characterization of ADA responses, including neutralizing activity.
From Nonclinical Strategy to GLP Execution: Partnering with the Right Preclinical GLP-certified Toxicology CRO
For biotechnology-derived therapeutics, designing an appropriate nonclinical safety program requires more than selecting a predefined set of toxicity studies. The therapeutic modality, mechanism of action, pharmacological activity, relevant species, potential safety liabilities, and regulatory requirements all need to be considered when developing the GLP strategy.
Early decisions can have a significant impact on the quality and interpretability of the subsequent safety package. Selecting a non-relevant species, inappropriate endpoints, or an assay that does not address the underlying safety question may generate data with limited value for clinical translation.
At InnoSer, we work with you to translate the biological characteristics of your therapeutic into a scientifically justified immunotoxicity assessment strategy and broader nonclinical testing strategy.
Early scientific input can also help identify potential challenges before a pivotal GLP study begins. Where appropriate, exploratory pharmacology, translational models or targeted immune-function assays can help inform the selection of the subsequent regulatory safety studies.
By bringing together exploratory pharmacology, relevant test systems, immunotoxicology, toxicokinetics, and GLP toxicology, InnoSer can support sponsors from early nonclinical planning through execution of the regulatory safety program.
Our support can include:
- GLP repeated-dose toxicology studies
- Toxicokinetic assessment and systemic exposure evaluation
- Immunogenicity and ADA assessment
- Immunotoxicity and immune-function investigations
- Relevant animal model and test-system selection
- Translational and exploratory preclinical studies
- Customized study design and endpoint selection
Our GLP infrastructure includes:
- GLP-certified toxicology capabilities since 2004
- Two GxP archives, full audit trail, with client audit rights
- GLP-certified histopathology platform with assessments performed by a board-certified veterinary histopathologist
Planning a nonclinical development program for a biotechnology-derived therapeutic? Talk to our team about designing the appropriate immunotoxicity testing strategy under full GLP compliance.
