Development of  ⁶⁸Ga‐Glycopeptide as an Imaging Probe for Tumor Angiogenesis

Abstract

Objective. This study was aimed to study tissue distribution and tumor imaging potential of 68Ga-glycopeptide (GP) in tumor-bearing rodents by PET. Methods. GP was synthesized by conjugating glutamate peptide and chitosan. GP was labeled with 68Ga chloride for in vitro and in vivo studies. Computer outlined region of interest (counts per pixel) of the tumor and muscle (at the symmetric site) was used to determine tumor-to-muscle count density ratios. To ascertain the feasibility of 68Ga-GP in tumor imaging in large animals, PET/CT imaging of 68Ga-GP and 18F-FDG were conducted in New Zealand white rabbits bearing VX2 tumors. Standard uptake value of tumors were determined by PET up to 45 min. To determine blood clearance and half-life of 68Ga-GP, blood samples were collected from 10 seconds to 20 min. Results. Radiochemical purity of 68Ga-GP determined by instant thin-layer chromatography was >95%. Tumor uptake values (SUV) for 68Ga-GP and 18F-FDG in New Zealand white rabbits bearing VX2 tumors were 3.25 versus 7.04. PET images in tumor-bearing rats and rabbits confirmed that 68Ga-GP could assess tumor uptake. From blood clearance curve, the half-life of 68Ga-GP was 1.84 hr. Conclusion Our data indicate that it is feasible to use 68Ga-GP to assess tumor angiogenesis.

Two-Chain Mature Hepatocyte Growth Factor-Specific Positron Emission Tomography Imaging in Tumors Using 64Cu-Labeled HiP-8, a Nonstandard Macrocyclic Peptide Probe

“…The half-lives of approximately 1.5 min in the distribution phase of both 64 Cu-labeled HiP-8 probes were reasonable for peptide PET probes passing through the glomerulus. 40,41 The TACs in the liver, kidneys, and bladder were, however, different between the two probes. Conflicting characteristics of renal clearance of the probes (more rapid urinary excretion of 64 Cu-CB-TE1K1P-HiP-8 and higher renal accumulation of 64 Cu-CB-TE1K1P-HiP-8-PEG11) indicate different degrees of tubular reabsorption.…”

99mTc-N4amG: Synthesis biodistribution and imaging in breast tumor-bearing rodents

“…Olinda inputs were calculated using established method(Wei, Tsao et al 2008; Tsao, Wang et al 2011). Briefly, fitted residence time functions were plotted and multiplied by the exponential decay functions (i.e.…”

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“…Glycopeptides are widely used as targeting molecules that can be attached to a molecule of interest to be targeted to a particular cellular location. Tsao et al have studied the tissue distribution and imaging potential of 68 Ga-glycopeptide using Positron Emission Tomography (PET) 19 . Richter et al have reviewed the potential of radio-labeled peptides in diagnostic imaging and therapy 20 .…”