Preclinical Services for RDC

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Project Description

Please note that we are not a pharmacy or clinic, so we are unable to see patients and do not offer diagnostic and treatment services for individuals.

Fluorescence/Optical Imaging

The integration of fluorescence or optical imaging into the preclinical pipeline provides an indispensable, high-sensitivity approach for visualizing molecular interactions and drug distribution in real-time. Alfa Cytology offers tailored, end-to-end solutions for radionuclide drug conjugate (RDC) development, bridging the gap between molecular design and therapeutic efficacy. By combining advanced optical probes with comprehensive analytical platforms, every project benefits from a seamless workflow designed to accelerate candidate selection and development.

Overview of Fluorescence/Optical Imaging

Fluorescence/optical imaging enables real-time, non-invasive tracking of RDC candidates in small animal models through the detection of emitted light from fluorophores or bioluminescent reporters. In the context of RDC development, these techniques utilize light-emitting probes, often in the Near-Infrared (NIR) spectrum, to track the localization, target engagement, and metabolic fate of conjugates. This modality serves as a high-throughput, cost-effective complement to nuclear imaging, providing high-sensitivity detection and multi-target capabilities that are vital for early-stage screening.

124I-A11 cMb-Cy5.5 enabled specific visualization of PC3-PSCA subcutaneous tumors via both PET and fluorescence signals. Fig.1 PET and fluorescence imaging with ¹²⁴I-A11 cMb-Cy5.5 demonstrated specific targeting of subcutaneous PC3-PSCA tumors. (Tsai, W. K., et al., 2018)

Principle of Fluorescence/Optical Imaging

The fundamental mechanism relies on the excitation of specialized fluorophores or bioluminescent reporters that emit photons upon absorbing specific wavelengths of light. As the fluorophore returns to its ground state, it releases the absorbed energy as emitted light at a longer wavelength (a phenomenon termed the Stokes shift), which is captured by a sensitive detector (e.g., a cooled charge-coupled device camera or a complementary metal-oxide-semiconductor sensor). This optical signal is then processed to generate high-contrast, high-spatial-resolution images, allowing for the precise localization and quantification of fluorophore-labeled RDC constructs within living subjects.

Application of Fluorescence/Optical Imaging

Lead Candidate Screening: Rapidly identifying RDC conjugates with optimal tumor-to-background ratios before performing radioactive labeling.
Internalization & Trafficking: Combining fluorescence microscopy (in vitro/ex vivo) with in vivo imaging to study how RDC molecules are internalized by cancer cells and subsequently distributed in tissues.
Pharmacokinetics (PK) Assessment: Long-term tracking of conjugate stability and clearance pathways using NIR-II dyes for deeper tissue penetration.
Multimodal Correlation: Directly comparing in vivo whole-body distribution (via PET/SPECT) with ex vivo histological validation (via Fluorescence).

Advantages of Fluorescence/Optical Imaging for RDC Preclinical Development

Utilizing optical imaging within RDC development protocols offers a distinct strategic edge, primarily through its high throughput and ability to provide complementary spatial context to nuclear imaging.

High Throughput & Rapid Screening

Multiple animals can be imaged simultaneously, enabling rapid screening of linker payloads, chelators, and conjugation strategies.

Cost & Regulatory Efficiency

By using fluorescent surrogates during initial PK pilots, researchers can minimize the use of radioactive isotopes, reducing costs and streamlining biosafety compliance.

High Sensitivity & Multiplexing

Capable of detecting picomolar concentrations of probes and enabling multi-color labeling, providing complementary insights that nuclear imaging cannot achieve alone in superficial or ex vivo settings.

Deep Tissue Compatibility

The platforms support NIR-II imaging, achieving centimeter-scale penetration in murine models with significantly reduced background autofluorescence under optimized conditions.

Our Services

Leveraging state-of-the-art instruments and deep expertise in radiochemistry and RDC biology, Alfa Cytology's service portfolio provides end-to-end support from fluorescent probe synthesis and in vitro validation to longitudinal in vivo imaging and quantitative analysis. Customized study designs accommodate diverse targets, tumor models, and regulatory submission requirements.

Workflow for Fluorescence/Optical Imaging Services in RDC Development

Consultation & Study Design: Defining target indications, conjugate architecture, and desired readouts (e.g., circulation half-life, target-to-muscle ratio).
Fluorophore Conjugation & QC: Labeling RDC candidates with validated NIR dyes; confirming purity, labeling efficiency, and fluorescence activity.
In Vitro Validation: Testing fluorescence stability, serum binding, and target-specific uptake in relevant cell lines.
In Vivo Dosing & Imaging: Administration into rodent models followed by time-course imaging (from 0.5h to 72h or more).
Data Processing & Analysis: ROI quantification, signal decay fitting, and 3D tomographic reconstruction.
Ex Vivo Confirmation: Terminal dissection with organ fluorescence measurement and correlation with histological sections.

Multi‑Isotope Capability

Preclinical RDC programs often combine optical imaging with nuclear imaging (PET/SPECT) to leverage the strengths of each: Optical for high-throughput screening and superficial high-resolution tracking, and nuclear for absolute deep-tissue quantification. We support parallel or sequential studies using the following isotopes.

Isotope	Half‑life	Imaging Type	Typical Applications
¹⁸F	110 min	PET	Short-lived labeling of small molecules; correlating NIR signals with dynamic PET for rapid PK studies.
⁶⁸Ga	68 min	PET	Rapid kinetic profiling for peptide-based RDCs; integrated PET/Optical for micro-lesion detection.
⁶⁴Cu	12.7 h	PET	Ideal for peptides and fragments; dual-modality fusion for detailed dosimetry and distribution mapping.
⁸⁹Zr	78.4 h	PET	Long-term distribution of antibody-RDCs; NIR-II correlation for deep tumor targeting and internalization.
⁹⁹ᵐTc	6.01 h	SPECT	High-throughput variant screening; SPECT/Optical fusion for cost-effective organ-level distribution.
¹²³I	13.2 h	SPECT	Iodinated RDCs; co-registered with optical signals for precise microscopic localization and metabolism.
¹¹¹In	2.80 d	SPECT	Long-circulating conjugates (liposomes/nanoparticles); validation of vascular permeability via optical dyes.
⁴⁷Sc	3.35 d	SPECT	Emerging theranostic label; using fluorescence to assess target binding before ⁴⁷Sc therapeutic pilots.
¹⁵³Sm	46.3 h	SPECT	Bone-targeting RDCs; optical imaging for longitudinal monitoring of skeletal metastatic response.
¹⁶¹Tb	6.89 d	SPECT	Multi-gamma/Auger emitter; fluorescence used to track cellular-level uptake and therapeutic efficacy.
¹⁸⁸Re	17.0 h	SPECT	Theranostic RDC label; SPECT/Optical for early response imaging and verification.
¹³¹I	8.02 d	SPECT	Classic theranostic isotope; optical imaging monitors tumor volume while SPECT tracks therapeutic dose.
…	…	…	…

Types of Preclinical Fluorescence/Optical Imaging Services

2D Fluorescence Reflectance Imaging (FRI) & Screening

As a highly efficient rapid screening tool, FRI enables real-time imaging of superficial tumor models or subcutaneous implants. This service is primarily utilized in the early stages of RDC development to evaluate the impact of different linkers or chelators on targeting efficiency by detecting fluorescence intensity. Its advantages include high speed and high throughput, supporting the simultaneous observation of multiple animals to provide critical preliminary data before committing to expensive nuclear imaging studies.

3D Fluorescence Molecular Tomography (FMT) & Bio-analysis

FMT technology overcomes the limitations of traditional planar imaging by using 3D tomographic reconstruction algorithms to quantitatively analyze RDC distribution within deep tissues. This service accurately determines the volume and spatial concentration of fluorescence signals within tumor tissues while eliminating background autofluorescence. It is essential for assessing RDC accumulation in deep organs like the lungs or liver, providing researchers with a semiquantitative localization approach that is similar to that of PET/SPECT in superficial lesions.

NIR-I & NIR-II Advanced Optical Imaging Solutions

We provide cutting-edge imaging solutions covering both the Near-Infrared I and II windows. NIR-II imaging has become a cornerstone of preclinical research due to its superior tissue penetration and minimal background scattering. This service is particularly suited for observing RDC transport within complex tumor microenvironments, achieving centimeter-scale detection depth and vessel-level contrast to provide high-SNR visual evidence for pharmacokinetic studies in subcutaneous or orthotopic models.

Dual-Modality & Multimodal Probe Development Services

Specialize in the development of "hybrid" probes that integrate fluorescent dyes with radionuclide chelating groups. Through this service, researchers can achieve a perfect alignment between macroscopic radioactive quantification and ex vivo fluorescence microscopic validation within the same animal cohort. This not only addresses the depth limitations of pure optical imaging but also enables fluorescence-guided analysis of micro-lesions in ex vivo tissues, ensuring high internal consistency across RDC research data.

Why Choose Us?

Deep RDC Domain Expertise: Specialist knowledge in the unique chemistry of radionuclide conjugates ensures that optical tags do not interfere with biological targeting or pharmacokinetics.
Rigorous Data Validation: Every report is backed by comprehensive histopathological correlation and ex vivo verification, ensuring that preclinical findings are robust and reliable.
Customized Solution Design: Bespoke strategies are offered to meet diverse R&D needs, including pre-development validation (where fluorescent tags are not coupled with isotopes) and sophisticated multimodal probe development (integrating fluorophores and radionuclides into a single conjugate).
End‑to‑End Services: Radiolabeling, radiochemistry, optical probe design, and full preclinical imaging are fully integrated, eliminating the delays and data discontinuities common with fragmented service providers.

Contact Us

Alfa Cytology is dedicated to advancing the next generation of precision radiopharmaceuticals through rigorous optical validation and innovative imaging strategies. To discuss how these fluorescence/optical Imaging services can be tailored to a specific RDC program, please reach out to the technical consulting team today for a detailed project evaluation.

Reference

Tsai, Wenting K et al. "Dual-Modality ImmunoPET/Fluorescence Imaging of Prostate Cancer with an Anti-PSCA Cys-Minibody." Theranostics 8.21 (2018): 5903-5914.

For research use only. Not intended for any clinical use.