iRelate: Assessment of PET Tracers to Evaluate Immunotherapy Treatment Response

Overview

Despite the potential of immunotherapy (IO), a minority of patients respond to treatment. As effective IO treatments enhance T cell infiltration and activation, understanding T cell behavior is paramount for developing successful treatment strategies. Biopsies are used to assess T cell states, but are invasive and may not accurately reflect tumor burden. Positron emission tomography (PET) imaging holds promise as a non-invasive, comprehensive means for evaluating T cell activity.

The iRelate project aims to assess T cell presence and activation state using two PET ligands in clinical development: [⁸⁹Zr]Zr-Df-IAB22M2C, a CD8a-targeting minibody developed by ImaginAb; and [¹⁸F]F–AraG, a mitochondrial enzyme-targeting small molecule developed by CellSight. Using both PET tracers will enable characterization of tracer uptakes in tumor tissue and T-cell-rich organs and is expected to provide information on unique and additive capacities of these tracers. This work is intended to serve as a foundation for defining potential context of use for PET biomarkers, and to support the development and selection of successful IO treatment strategies.