A Study of [225Ac]-FPI-1966 in Participants With Advanced Solid Tumours

In phase 1, cohort 1, the potential impact of pre-dose administration of vofatamab on the dosimetry, PK, safety, and tolerability of \[225Ac\]-FPI-1966 and \[111In\]-FPI-1967 will be evaluated. In later phase 1 cohorts, \[225Ac\]-FPI-1966 will be evaluated at ascending dose levels. Participants will receive \[111In\]-FPI-1967 during the imaging screening period to assess FGFR3 expression and to determine biodistribution and estimate radiation exposure to critical organs. Once the recommended phase 2 dose (RP2D) or regimen is established and confirmed, three tumour-agnostic expansion cohorts may be initiated in parallel.