An ²¹¹At-labeled Tetrazine for Pretargeted Therapy

Area of Science:

• Nuclear medicine
• Radiochemistry
• Oncology

Background:

• Pretargeted radioimmunoimaging enhances tumor-to-background ratios, improving radionuclide therapy efficacy and safety.
• Shorter half-life radionuclides like astatine-211 (²¹¹At) are suitable for pretargeted strategies.
• Tetrazine ligation is a key bioorthogonal reaction for ²¹¹At labeling and biodistribution control.

Purpose of the Study:

• To develop and evaluate a novel ²¹¹At-labeled pretargeting agent for alpha-radionuclide therapy.
• To assess the efficacy of pretargeted imaging in achieving higher tumor-to-blood ratios compared to direct labeling.

Main Methods:

• Development of an ²¹¹At-labeled pretargeting agent.
• Radiochemical yield and purity assessment (>99%).
• Comparison of tumor-to-blood ratios with directly labeled monoclonal antibodies within 24 hours.

Main Results:

• Achieved a radiochemical yield of approximately 65% for the ²¹¹At-labeled agent.
• Demonstrated higher tumor-to-blood ratios within the first 24 hours post-administration compared to direct labeling.
• Observed deastatination, indicating a need for further optimization.

Conclusions:

• ²¹¹At-labeled pretargeting agents show promise for alpha-radionuclide therapy by improving tumor targeting.
• Pretargeted therapy may deliver superior tumor doses compared to conventional methods.
• Future tetrazine developments should address observed deastatination for enhanced therapeutic outcomes.