Crefmirlimab (⁸⁹Zr-Crefmirlimab Berdoxam): A Novel Anti-CD8 Minibody for PET Imaging in Immuno-Oncology

1. Introduction to Crefmirlimab and Zirconium Zr 89 Crefmirlimab Berdoxam

Overview and Significance as a Diagnostic Agent

Crefmirlimab is an investigational anti-human CD8α probe developed for the diagnosis of various cancers by targeting the CD8A antigen, a key marker on cytotoxic T-lymphocytes.[1] When Crefmirlimab is conjugated with the chelator desferrioxamine (Df) and radiolabeled with the positron-emitting isotope Zirconium Zr 89 ($^{89}$Zr), it forms the radioimmunoconjugate known as Zirconium Zr 89 crefmirlimab berdoxam.[4] This agent is specifically designed for non-invasive Positron Emission Tomography (PET) imaging to visualize, track, and quantify CD8-expressing T-cells in vivo.[4]

The strategic importance of such an agent stems from the central role of CD8+ T-cells in mediating anti-tumor immunity, particularly in the context of cancer immunotherapy.[5] The presence, density, and changes in the distribution of these immune effector cells within the tumor microenvironment and other lymphoid tissues can be critical indicators of a patient's immune status and their response to immunotherapeutic interventions.[5] Traditional methods for assessing CD8+ T-cell infiltration, such as immunohistochemistry (IHC) on biopsy samples, are invasive, provide only a localized snapshot of a single lesion at a single point in time, and may not reflect the heterogeneity of the immune response across all tumor sites or the dynamic changes occurring during treatment.[7]