Pet imaging of cytotoxic human T cells using an 89Zr-labeled anti-CD8 minibody.

Background Major challenges to advancing the new wave of cancer immunotherapies are to select patients who will respond to single immunotherapies, identify those who need more tailored combination regimens, and then, determine early during treatment whether the therapy is working. “ImmunoPET” imaging of tumor infiltrating T cells with radiolabeled antibody fragments can provide a specific and sensitive modality to achieve this goal. For this purpose we have developed Zr-Df-IAB22M2C, an antiCD8 minibody (Mb) conjugated with desferrioxamine (Df) and radiolabeled with Zr for imaging human CD8 T cells in man.