Biodistribution and radiation dosimetry of the PDGFRβ targeting PET tracer [68Ga]Ga-ATH001

Purpose [ 68 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 [ 68 Ga]Ga-ATH001 biodistribution and radiation dosimetry data. Methods Radiation dosimetry of [ 68 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 [ 68 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. Results The effective dose of [ 68 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. Conclusion [ 68 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.