²²⁵Ac-FPI-1434 (²²⁵Ac-FPX-01) is an Alpha labeled antibody under development for the treatment of solid tumors. ²²⁵Ac-FPI-1434 is a targeted Alpha radioimmuno-therapeutic agent that consists of FPI-1175, an insulin-like growth factor-1 receptor (IGF-1R)-targeting humanized monoclonal antibody, a bifunctional chelate (FPI-1397), and Actinium-225.

IGF-1R is up-regulated in numerous chemo-resistant cancers. ²²⁵Ac-FPI-1434 has a potential to target and destroy most of the solid tumors including lung, colorectal, hepatic, gastric, prostate, breast, ovarian, endometrial and head neck. The primary target for ²²⁵Ac-FPI-1434 is not known yet.

²²⁵Ac-FPI-1434 has completed preclinical development under the name ²²⁵Ac-FPX-01. Biodistribution in animal with ¹²⁴I-FPX-01 on different types of solid tumors has shown high selectivity. Additional preclinical studies comparing Biodistribution of ¹¹¹In, ¹⁷⁷Lu and ²²⁵Ac analogues have been published in 2018.

Clinical Phase I/II study with ²²⁵Ac-FPI-1434 using the indium analogue for SPECT Imaging and selection of patients, ¹¹¹In-FPI-1547 was initiated in January 2019. No specific cancer was targeted and patient recruitment is based on advanced solid tumors refractory to all standard treatment, for which no standard treatment is available or the patient refuses standard therapy. This study is expected to be completed by June 2026, with primary completion data available by June 2023.

Target/Mechanism: IGF-1R

Carrier/Ligand: FPI-1434

Radiation Type: Alpha particle (α)