Immuno-PET – Precision Imaging of Antibody Biodistribution

With hundreds of monoclonal antibodies (mAb), antibody fragments, antibody drug conjugates, and other antibody scaffolds in development, the use of immuno-PET in preclinical research for in vivo tracking and quantification of these compounds has advanced rapidly. MI Bioresearch has been at the forefront of this advancement, being one of the first commercial CROs to offer immuno-PET to biotechnology drug developers.

In combining our state-of-the-art small animal bimodal PET/CT and trimodal PET/SPECT/CT instruments with our rodent models expertise, we can image time-resolved and quantitative biodistribution of radiolabeled biologics in naïve and disease bearing animals. We work with trusted radiochemistry partners to develop a radiolabeling protocol for your biologic and coordinate delivery to our site of the radiolabeled biologic for in vivo study. We are licensed to work with a range of positron emitters including zirconium-89 (89Zr) and iodine-124 (124I), commonly used in immuno-PET.

SPECT Isotopes

Isotope Half Life Energy in KeV Common Applications/Strengths
Technetium-99m [99mTc] 6 hours 140.5 Most common clinical SPECT isotope; bone imaging
Iodine-123 [123I] 13.2 hours 159 Neuro-imaging
Indium-111 [111In] 2.8 days 171.3, 245.4 Biodistribution
Gallium-67 [67Ga] 3.3 days 93.3, 184.6, 300 Translatable to [68Ga] PET radiotracer
Lutetium-177 [177Lu] 6.73 days 113, 210 Radiotherapy
Thallium-201 [201TI] 12.23 days 135, 167 Cardiac imaging
Tin-117m [117mSn] 14 days 158.6 Long-term biodistribution
Iodine-125 [125I] 59 days 27 to 32 Iodination

PET Isotopes

PET Isotope Half Life Common Applications
Fluorine-18 [18F] 1.8 hours FLT, FDG
Copper-64 [64CU] 12.7 hours Short term tacking of small molecules and peptides; imaging of disease state and efficacy using targeted biologics
Yttrium-86 [86Y] 14.7 hours Analog of [90Y] radiotherapy isotope that can be used for imaging studies
Cobalt-55 [55Co] 17.5 hours Characterization of tissue infarct regions
Iodine-124 [124I] 4.2 days Iodination labeling of proteins
Zirconium-89 [89Zr] 3.27 days Biodistrobutions

Case Study

Antibody Biodistribution In Vivo With Zirconium-89 PET

Zirconium-89 (89Zr) has revolutionized discovery and translation of Ab (and Ab fragment) therapeutics via PET biodistribution imaging. With standard, straightforward labeling chemistry, 89Zr provides unprecedented specificity and sensitivity of PET Ab detection (to pM levels). We use 89Zr PET as a platform assay for in vivo quantification of:

  • Ab targeting precision
  • Off-target localization
  • Clearance

Read our corresponding blog: Precision Imaging of Antibody Biodistribution in vivo With Zirconium-89 PET

Zr89 PET - Ab Targeting Graphic

Comparison of tumor penetration
Comparison of tumor penetration of 89Zr-cetuximab and in combination is compared in a tumor-burdened mouse using immuno-PET

Our assays allow preclinical assessment of acute Ab kinetics as well as longitudinal time courses over >1 week in the whole body.

Determination of Biodistribution Using Fluorescence Imaging (FLI)

Efficient and quantitative characterization of biologics targeting and biodistribution can be achieved in a variety of tissues using 3D fluorescence imaging of fluorescent-labeled agents. A variety of fluorophore kits are available for antibody, protein, and nanoparticle labeling. Blood sampling and ex vivo imaging can be combined with in vivo imaging for further quantitation of pharmacokinetics and pharmacodynamics of systemically introduced biologics. We have extensive experience with these in vivo biodistribution studies that allow interrogation of targeting and kinetics during the early discovery phase, prior to more elaborate, translational radiolabeling approaches that are more labor- and cost-intensive.