Definition

A radioimmunoconjugate comprised of a minibody (Mb), an inert antibody fragment against the human CD8-antigen on CD8-positive T cells, conjugated to the chelator desferrioxamine (Df) and labeled with the radioisotope zirconium Zr 89, with potential positron emission tomography (PET) imaging activity. Upon administration, zirconium Zr 89 crefmirlimab berdoxam specifically targets and binds to the CD8 antigen expressed on T cells. This enables PET detection of the radioisotope moiety, and may allow the imaging, tracking and quantification of CD8-expressing T-cells. This may detect CD8-positive T-cell distribution and activity, and may help determine the patient’s response to cancer immunotherapeutic agents. CD8-positive T cells play a key role in the eradication of cancer cells. Although the Mb has the same antigen specificity and binding affinity as the full-length antibody, the Mb does not activate or induce the proliferation of CD8-positive T cells.