Actinium-225 FPI-1434 to Target Solid Tumours

Actinium-225 FPI-1434, targeting IGF-1R, shows promise in treating resistant solid tumours, advancing from preclinical stages to clinical trials.

Introduction to Actinium-225 FPI-1434 (Actinium-225FPX-01)

Actinium-225 FPI-1434, previously known as 225Ac-FPX-01, is an innovative alpha-labelled antibody being developed for the treatment of various solid tumours. This therapeutic agent represents a significant advancement in oncology, particularly in treating tumours resistant to conventional chemotherapy.

The agent comprises three primary components: FPI-1175, a humanised monoclonal antibody targeting the insulin-like growth factor-1 receptor (IGF-1R); a bifunctional chelate, FPI-1397; and the radioisotope Actinium-225. The targeting mechanism 225Ac-FPI-1434 is grounded in its affinity for the IGF-1R, which is commonly overexpressed in numerous chemo-resistant cancers.

Targeting IGF-1R in Cancer Therapy

IGF-1R plays a crucial role in the development and progression of many solid tumours. By targeting this receptor, 225Ac-FPI-1434 has the potential to deliver therapeutic radiation directly to the cancer cells, minimising damage to the surrounding healthy tissues.

The Broad Potential of Actinium-225 FPI-1434

One of the most promising aspects of 225Ac-FPI-1434 is its potential applicability across a wide range of solid tumours, including lung, colorectal, hepatic, gastric, prostate, breast, ovarian, endometrial, and head and neck cancers. The exact primary target of 225Ac-FPI-1434 is yet to be determined, which opens avenues for extensive research and application.

Preclinical Development: 225Ac-FPX-01

Before being named 225Ac-FPI-1434, the agent underwent preclinical development as 225Ac-FPX-01. Studies involving biodistribution in animals using 124I-FPX-01 demonstrated high selectivity for various types of solid tumours. Further comparative preclinical studies with isotopes like 111In, 177Lu, and 225Ac analogues were published in 2018, highlighting the agent’s potential efficacy.

Clinical Development and Trials

The clinical Phase I/II study of 225Ac-FPI-1434 commenced in January 2019. This trial employed the indium analogue, 111In-FPI-1547, for SPECT imaging and patient selection. The study is unique in that it does not target a specific cancer type; instead, it focuses on patients with advanced solid tumours that are refractory to standard treatments or for those who have declined conventional therapy.

Study Completion and Expectations

The study is anticipated to be completed by June 2026, with primary completion data expected to be available by June 2023. This timeframe allows for a thorough evaluation of the efficacy and safety of 225Ac-FPI-1434 in a clinical setting.


Actinium-225 FPI-1434 represents a groundbreaking approach in the fight against solid tumours, particularly those resistant to conventional therapies. Its targeted mechanism, broad potential applicability, and ongoing clinical trials make it a significant development in the field of oncology.

Future Perspectives

As research and clinical trials continue, 225Ac-FPI-1434 holds great promise for becoming a pivotal treatment option for patients battling various solid tumours. Its targeted approach and potential efficacy in addressing chemo-resistant cancers could revolutionise treatment protocols and improve outcomes for many patients.

The Road Ahead

The successful development of 225Ac-FPI-1434 could lead to more personalised and effective cancer treatments, marking a significant step forward in precision medicine. Further research into the mechanisms of action, potential side effects, and long-term efficacy of this treatment will be crucial in determining its place in cancer therapy.

The Role of Actinium-225 FPI-1434 in Cancer Research

Actinium-225 FPI-1434 is not just a potential treatment option; it also represents a valuable research tool for understanding the role of IGF-1R in cancer progression. Insights gained from developing and applying this agent could pave the way for new discoveries in cancer biology and therapeutics.

Implications for Future Therapies

The development of 225Ac-FPI-1434 could inspire the creation of similar targeted therapies for other types of cancers. This could lead to a new era of treatment where radioimmunotherapy plays a central role, especially for tumours that are currently hard to treat.

Actinium-225 FPI-1434 (225Ac-FPX-01) is a promising alpha-labelled antibody under development that targets a range of solid tumours. Its unique composition and targeted approach against IGF-1R-positive tumours make it a potential game-changer in oncology. The medical community closely watches the ongoing clinical trials and research as they hold the potential to transform the landscape of cancer treatment.

As we await the outcomes of these trials and studies, 225Ac-FPI-1434 stands as a beacon of hope for many patients facing the challenges of chemo-resistant cancers. Its development offers a new therapeutic option and contributes significantly to our understanding of cancer biology and treatment.

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