Translational CAR-T Evaluation: In Vitro Expertise & NHP Study Support — Prisys Biotech

Chimeric antigen receptor T-cell (CAR-T) therapies have transformed treatment paradigms for certain haematologic malignancies and are under active investigation for solid tumours. Despite clinical successes, translation from bench to bedside remains challenging. Immune-related adverse events such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are major safety considerations during clinical development, and predicting their incidence and severity preclinically is difficult.

Traditional rodent models-particularly immune-deficient mouse xenografts-are indispensable for initial proof-of-concept and mechanism studies but have well-recognised limitations when modelling human systemic immune responses. Non-human primates (NHPs), owing to closer immunological homology with humans, provide complementary information on safety, biodistribution and some aspects of immune dynamics that are difficult to capture in rodents.

For translational teams evaluating CAR-T candidates, NHP studies can add value in several specific areas:

1. Improved safety signal detection (CRS and neurotoxicity modelling)
Rodent systems frequently fail to reproduce the systemic cytokine cascades observed in severe CRS or the complex neurological sequelae of ICANS. In NHPs, serial sampling of cytokines (e.g., IL-6, IFN-γ, TNF-α) combined with standardised behavioural and neurological assessments enables a more clinically relevant evaluation of acute systemic immune activation and its temporal profile.

2. On-target / off-tumour risk assessment
Many CAR targets have low-level expression on normal tissues. The high amino-acid sequence homology between human and NHP proteins for many antigens permits more realistic cross-reactivity testing, supporting early identification of potential on-target, off-tumour toxicities that are not evident in rodent models.

3. PK/PD insight for cell therapies
Key pharmacodynamic properties for CAR-T-expansion kinetics, persistence, phenotypic evolution, and trafficking-are influenced by interactions with an intact adaptive immune compartment. NHPs provide an immune-competent context in which to profile these dynamics longitudinally, which can inform clinical dose selection and sampling strategies.

Appropriate interpretation and limitations

NHP experiments are not a perfect surrogate for human outcomes. Important limitations include species-specific differences in receptor expression, immune regulation and the practical constraints on tumour modelling in NHPs (for example, engrafting human tumours into NHPs is generally not feasible). Therefore, NHP data should be integrated with robust in vitro functional characterisation, rodent efficacy models, and translational biomarkers to form a weight-of-evidence approach for first-in-human trial design.

Prisys Biotech offers a suite of preclinical services designed to strengthen translational confidence while maintaining rigorous welfare and data-quality standards. To ensure scientific transparency, we clarify our actual experience and scope:

Experience statement (accurate reflection):
Prisys has established capabilities in in vitro CAR-T characterisation, including cytotoxicity assays, cytokine multiplex profiling, flow cytometry-based phenotyping, and functional T-cell assays. We have not performed autologous or allogeneic CAR-T infusions into NHPs to date. However, our in vitro platform and immunology expertise underpin our ability to design and execute integrated preclinical strategies that bridge in vitro findings and in vivo evaluation conducted in collaboration with appropriate partners or sponsors.

What we can provide directly:

• Customised in vitro assay suites for CAR-T functional characterisation (killing assays, serial re-challenge, exhaustion markers, cytokine release panels).
• High-content flow cytometry panel design and validation for CAR expression, differentiation/exhaustion markers, proliferation and activation phenotyping.
• Multiplex cytokine / chemokine profiling with time-course analyses to define release kinetics under controlled stimulation conditions.
• In vitro cross-reactivity testing against relevant NHP primary cells or cell lines where available, to support target expression and off-target risk assessment.

How we support in vivo programmes (collaborative model):

• Translational study design: we advise on NHP study endpoints, sampling schedules, biomarker selection, and humane monitoring plans informed by in vitro data.
• Assay transfer and GLP-compatible reporting: we prepare assay SOPs, analytical plans, and data packages suitable for regulatory submissions.
• Partner coordination: when in vivo NHP studies are required, Prisys can coordinate with qualified NHP facilities or sponsor-designated vivaria to implement studies and to ensure continuity between in vitro characterisation and in vivo biomarker sampling/assays.

When designing preclinical CAR-T programmes intended to inform clinical translation, we recommend integrating the following elements:

• Preclinical lymphodepletion modelling where scientifically justified, with careful dose-effect evaluation and translational justification for agents (e.g., cyclophosphamide, fludarabine) and timing relative to cell infusion.
• Standardised, prospectively defined safety endpoints (graded CRS/ICANS metrics adapted to species), combined with predefined cytokine/biomarker panels and neurological/behavioural observation schedules.
• Serial peripheral blood monitoring for CAR transgene kinetics (qPCR or digital PCR), immunophenotyping, and cytokine profiling to characterise expansion-persistence relationships.
• Tissue biodistribution sampling (where ethically and logistically appropriate) to assess organ exposure and potential off-target localisation.

Effective translational evaluation of CAR-T candidates requires a layered approach that aligns rigorous in vitro characterisation with strategically designed in vivo studies. Prisys Biotech contributes deep immunology and assay expertise from our in vitro CAR-T work and supports sponsors by designing translational study frameworks, and coordinating with in vivo partners where necessary. Our objective is to generate data that meaningfully de-risk first-in-human plans while maintaining high standards of animal welfare and data integrity.