⁸⁹Zr-Labeled AR20.5: A MUC1-Targeting ImmunoPET Probe

Area of Science:

• Oncology
• Radiochemistry
• Molecular Imaging

Background:

• High MUC1 expression correlates with tumor aggressiveness and poor patient outcomes.
• MUC1 is a validated target for cancer imaging and therapy.
• Novel imaging agents are needed for accurate MUC1 detection.

Purpose of the Study:

• To synthesize and characterize a novel zirconium-89 labeled radioimmunoconjugate for MUC1 immunoPET imaging.
• To evaluate the in vivo performance of [89Zr]Zr-DFO-AR20.5 in preclinical ovarian cancer models.

Main Methods:

• Modification of the AR20.5 antibody with desferrioxamine (DFO).
• Labeling with zirconium-89 (89Zr) to create [89Zr]Zr-DFO-AR20.5.
• In vivo immunoPET imaging in mice bearing MUC1-expressing ovarian cancer xenografts (subcutaneous and orthotopic models).

Main Results:

• [89Zr]Zr-DFO-AR20.5 successfully delineated MUC1-expressing tumors in vivo.
• High tumoral activity concentration (19.1 ± 6.4 %ID/g) and tumor-to-muscle ratio (42.4 ± 10.6) were achieved at 120 h post-injection.
• Visualization of both primary tumors and metastatic lesions was demonstrated with good contrast.

Conclusions:

• [89Zr]Zr-DFO-AR20.5 is a promising novel radioimmunoconjugate for MUC1-targeted immunoPET imaging.
• This agent enables effective visualization of MUC1-expressing tumors, including metastases.
• Further development for clinical application in MUC1-positive cancers is warranted.