Biodistribution and radiation dosimetry of the PDGFRβ targeting PET tracer [<sup>68</sup>Ga]Ga-ATH001.

Lubberink, Mark; Lohith, Talakad G; Derdak, Zoltan; Wilkens, Paul; Palmér, Emilia; Ramolli, Alexandra; Ferrat, Mélodie; Tran, Thuy A et al. · Eur J Nucl Med Mol Imaging · 2026

case_series · Level IV

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Abstract

[<sup>68</sup>Ga]Ga-ATH001 is an Affibody molecule targeting PDGFRβ in development as a Positron Emission Tomography (PET) tracer for non-invasive imaging of active fibrosis. Here we present first-in-human [<sup>68</sup>Ga]Ga-ATH001 biodistribution and radiation dosimetry data. Radiation dosimetry of [<sup>68</sup>Ga]Ga-ATH001 was evaluated in healthy participants (n = 3) and participants with metabolic dysfunction-associated steatohepatitis (MASH) (n = 3). Each participant was intravenously administered ~ 2.5 MBq/kg [<sup>68</sup>Ga]Ga-ATH001 and imaged by whole-body PET for up to 3 h post-injection. Absorbed dose coefficients and effective doses according to ICRP 103 were calculated using IDAC DOSE 2.1. The effective dose of [<sup>68</sup>Ga]Ga-ATH001 was 0.028 ± 0.002 mSv/MBq with kidneys as the dose-limiting organ. Administration of a target dose of 2 MBq/kg would result in a sex-averaged effective dose of 4.1 mSv. Subjects tolerated the tracer administration well. [<sup>68</sup>Ga]Ga-ATH001 demonstrates a dosimetry and safety profile that supports further clinical development as a repeatable, non-invasive PET marker of active fibrosis in tissue.