A Study of [225Ac]-FPI-2059 in Adult Participants With Solid Tumours

"\[225Ac\]-FPI-2059 is a targeted alpha therapeutic that consists of an NTSR1-targeting small molecule that is linked to Ac-225, an alpha particle emitting radionuclide. Participants will be dosed through IV administration every 56 days up to four cycles. The dose depends on cohort assignment.~In the Dose Expansion arm, \[225Ac\]-FPI-2059 will be administered at the RP2D as determined in Phase 1 Dose Escalation."

\[111In\]-FPI-2058 is an imaging agent that consists of an NTSR1-targeting small molecule linked to In-111.Participants will receive \[111In\]-FPI-2058 by IV Injection for imaging once during screening period. The dose is consistent across cohorts.