Webinar Recap: Molecular Imaging in NHP Models For Translational Drug Development | Prisys

Translational drug development increasingly needs evidence that links systemic exposure to tissue distribution, target engagement, pharmacological activity, and functional response. In non-human primate (NHP) research, molecular imaging adds a layer of in vivo data that sits alongside conventional pharmacokinetic, pharmacodynamic, biomarker, and histological assessments.

In our recent webinar, "Molecular Imaging in NHP Models for Translational Drug Development," Prisys Biotechnologies discussed how multimodal imaging can be integrated with NHP disease models to generate longitudinal, spatially resolved evidence during preclinical development.

The session featured James Song, General Manager & Co-Founder, who covered the role of molecular imaging, imaging-guided procedures, and applications from biodistribution and PK/PD to target engagement and radiopharmaceutical development.

Conventional preclinical measurements capture information at defined study time points. Tissue concentrations, histological findings, biomarkers, and functional measurements each address part of how a drug acts, but they say little about how those processes evolve spatially and temporally within the same subject.

Molecular imaging addresses that gap by allowing selected biological processes to be assessed in vivo and longitudinally.

Three questions come up repeatedly in translational drug development:

• Where does the therapeutic go? Imaging shows organ- and tissue-level distribution and how it changes over time.
• Does the therapeutic reach the intended target? Where suitable molecular probes exist, imaging can be used to investigate target localization, receptor occupancy, or other measures of target engagement.
• How does exposure relate to biological response? Image-derived measurements can be read alongside plasma PK, PD biomarkers, and functional endpoints to give a more integrated picture of drug action.

NHP models are a useful translational setting here, because their anatomy, physiology, and selected disease characteristics bridge conventional preclinical models and clinical research.

The value of molecular imaging lies in adding spatial, temporal, and in vivo information to a study. It is not a substitute for conventional measurements.

The imaging strategy should follow the therapeutic modality, the target organ, and the scientific question. No single modality answers everything a translational study needs.

At Prisys, the multimodal imaging platform includes PET/CT, SPECT/CT, MRI, CT, and digital subtraction angiography (DSA), and these can be combined according to study objectives.

PET and SPECT detect radiolabeled tracers and are used for molecular and functional readouts. MRI provides high-resolution anatomical and functional information and is particularly useful for CNS research and image-guided procedures. CT adds anatomical detail, while DSA visualizes vascular anatomy and supports interventional work.

With this multimodal setup, imaging can serve as a study endpoint, and in selected studies as part of the experimental procedure itself.

Targeted drug delivery is one area where imaging has a direct procedural role.

For CNS studies, MRI-guided convection-enhanced delivery (CED) supports precise administration into selected brain regions, with imaging documenting delivery and local distribution.

For vascular and interventional work, DSA visualizes vascular anatomy and provides image-based confirmation during targeted procedures.

Imaging-guided strategies can be adapted to the anatomical and pharmacological requirements of individual organs. That creates a single workflow in which imaging supports administration, localization, and the assessment of distribution that follows.

Molecular imaging is one component of a wider translational assessment framework. During the webinar, Prisys also introduced its work on AI-assisted NHP behavioral monitoring.

Video-based analysis extracts behavioral features such as movement, posture, activity, trajectory, and position over time. Tracked longitudinally, these features can inform the evaluation of treatment-related functional changes and potential safety signals.

Such digital endpoints sit alongside imaging, PK/PD, and conventional assessments, adding to the longitudinal dataset available from an NHP study.

Molecular imaging can address several questions across the drug development process.

Imaging provides quantitative information about how a therapeutic or tracer distributes across organs and tissues over time. Unlike terminal tissue collection, longitudinal imaging allows repeated assessment in the same subject.

That matters when tissue exposure and organ-level distribution are central to the development question.

Imaging-derived kinetics can be evaluated alongside conventional plasma PK and pharmacodynamic measurements, which makes it possible to examine relationships between systemic exposure, tissue-level distribution, and biological response.

The two approaches measure different aspects of drug disposition and activity, so they are generally used together rather than interchangeably.

Where suitable molecular imaging probes are available, PET or SPECT can be used to investigate target localization, receptor occupancy, or other measures of target engagement.

These measurements provide spatial information that plasma sampling alone cannot. Interpreting them depends on the specificity of the imaging probe, labeling stability, pharmacology, and study design.

Imaging can also inform safety assessment, particularly where tissue distribution, organ accumulation, or treatment-related structural and functional changes are relevant to the study.

Imaging-derived observations should be read alongside conventional safety and toxicology endpoints, not as a standalone assessment.

For radiopharmaceutical development, quantitative PET or SPECT data supports assessment of tissue distribution and radiation exposure.

NHP imaging data can contribute to dosimetry and to translational evaluation of radio-based therapeutics. Dose projection still requires quantitative modeling and consideration of species differences, tracer behavior, radiochemistry, and study-specific assumptions.

Molecular imaging contributes more when imaging endpoints are designed together with an appropriate disease model and complementary biological measurements.

At Prisys, molecular imaging can be integrated with NHP disease models across CNS, cardiovascular, metabolic, renal, and inflammatory programs.

The framework links several layers of evidence:

NHP disease model → Imaging → Biodistribution / Target Engagement → PK/PD → Functional and biological endpoints

This lets different types of evidence be interpreted within the same translational framework, instead of relying on a single measurement.

One question raised during the webinar was whether molecular imaging can replace conventional pharmacokinetic analysis. In general, the two approaches provide different types of information.

Conventional PK analysis, such as LC-MS/MS measurement of plasma drug concentrations, quantifies systemic exposure. Molecular imaging, when based on an appropriately radiolabeled compound or molecular probe, shows where the compound goes in vivo.

Imaging and conventional PK are therefore best treated as complementary measurements.

One caveat applies: whether the radiolabel accurately represents the behavior of the parent compound or relevant molecular species. Label stability, metabolism, probe specificity, and tracer pharmacology all need to be considered when interpreting imaging-derived measurements.

Molecular imaging depends on having the right NHP models, experimental infrastructure, and biological endpoints in place.

Prisys integrates several capabilities within its NHP translational research platform:

• NHP Disease Models - Disease-relevant NHP models across multiple therapeutic areas
• Multimodal Imaging - PET/CT, SPECT/CT, MRI, CT, and DSA
• Imaging-Guided Delivery - CNS and organ-targeted approaches supported by image guidance
• Integrated Endpoints - Imaging combined with PK/PD, biomarkers, and functional assessment
• Radionuclide Applications - Support for PET and SPECT studies using radionuclides including 18F, 68Ga, 89Zr, 124I, 64Cu, 11C, 131I, 125I, and 99mTc
• AI-Assisted Behavioral Monitoring - Video-based longitudinal assessment of NHP behavior and activity

The aim is to connect NHP biology with quantitative in vivo measurements and additional biological endpoints, so that translational decisions rest on a broader evidence base.

Molecular imaging adds longitudinal, spatially resolved, image-derived information to NHP studies, which conventional preclinical assessment does not capture on its own.

Its applications extend from biodistribution and tissue exposure to target engagement, pharmacodynamic assessment, safety evaluation, and radiopharmaceutical dosimetry. Designed and integrated with NHP disease models, conventional PK/PD, biomarkers, and functional endpoints, molecular imaging can give a fuller picture of how a drug behaves in vivo.

The webinar recording and presentation materials are available for those who would like to explore these topics in greater detail.

For information about NHP molecular imaging studies or to discuss a potential translational research program, please contact the Prisys Biotechnologies team at bd@prisysbiotech.com.

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