DTPA-coupled antibodies labeled with yttrium-90

Area of Science:

• Nuclear medicine
• Radiopharmaceutical chemistry
• Oncology

Background:

• Yttrium-90 (90Y) is recognized for its therapeutic potential in oncology due to its physical and chemical properties.
• Availability via a strontium-90 (90Sr) radionuclide generator simplifies its acquisition for research and clinical applications.

Purpose of the Study:

• To evaluate the suitability of 90Y, obtained from a radionuclide generator, for labeling antibodies using diethylenetriaminepentaacetic acid (DTPA).
• To compare the in vitro stability and in vivo biodistribution of 90Y-labeled antibodies with those labeled with Indium-111 (111In).

Main Methods:

• Antibodies were coupled with DTPA and subsequently labeled with 90Y from a generator.
• In vitro stability of [90Y]DTPA-IgG was assessed in human serum at 37°C.
• Biodistribution studies were performed using 111In- and 90Y-labeled DTPA-coupled IgG in preclinical models, with imaging at 1 and 24 hours post-administration.

Main Results:

• 90Y obtained from a generator was successfully used to label DTPA-coupled antibodies.
• The dissociation rate of [90Y]DTPA-IgG in serum was comparable to [111In]DTPA-IgG, approximately 8-9% per day.
• Biodistribution patterns for 111In and 90Y labels were nearly identical at 1 hour but showed differences at 24 hours, potentially due to label redistribution after catabolism.

Conclusions:

• 90Y is a suitable radionuclide for labeling tumor-associated antibodies when chelated with DTPA.
• The stability and initial biodistribution of 90Y-labeled antibodies support their potential use in targeted tumor therapy.
• Further investigation into the observed 24-hour biodistribution differences may be warranted to fully understand the in vivo behavior of 90Y-labeled constructs.