Astatine-211 radioimmunotherapy represents a significant milestone in targeted alpha therapy for oncological management. This innovative treatment utilizes the short-range, high-energy alpha particles of Astatine-211 to eliminate cancer cells with high precision. However, off-target accumulation in organs like the stomach and thyroid often limits its clinical utility. Researchers have recently identified a dual-protection strategy that addresses these challenges without compromising therapeutic efficacy.

Enhancing Safety in Astatine-211 Radioimmunotherapy

The primary mechanism involves the use of sodium perchlorate (SP) alongside sodium ascorbate (SA). While sodium ascorbate prevents the denaturation of radioactive antibodies by neutralizing reactive oxygen species, it does not stop the accumulation of free Astatine in non-target tissues. Specifically, sodium perchlorate acts as a competitive inhibitor of the sodium iodide symporter (NIS). Since NIS is naturally expressed in gastric mucosal and thyroid follicular cells, its inhibition significantly reduces radioactive uptake in these areas. Consequently, this approach minimizes DNA double-strand breaks and maintains the structural integrity of the thyroid gland.

Furthermore, the study demonstrated that this combined strategy leads to significantly milder body weight loss. Additionally, the intervention did not exacerbate renal toxicity, hepatotoxicity, or transient hematotoxicity. Most importantly, the antitumor effect of the Astatine-211 radioimmunotherapy remained unaffected. Therefore, this method effectively broadens the therapeutic window, facilitating the safe clinical application of alpha-emitting radionuclides in cancer care.

How does sodium perchlorate reduce toxicity in At-RIT?

Sodium perchlorate acts as a competitive inhibitor of the sodium iodide symporter (NIS), which is responsible for the accumulation of Astatine-211 in the thyroid and stomach tissues.

Does NIS inhibition interfere with the antitumor effect of Astatine-211?

No, the research indicates that the antitumor efficacy remains consistent even when competitive NIS inhibition is used to protect normal organs.

What is the role of sodium ascorbate in this therapy?

Sodium ascorbate is used to protect radioactive antibodies from reactive oxygen species-induced denaturation, ensuring the stability of the radioimmunotherapy agent.

Disclaimer: This content is for informational and educational purposes only and does not constitute medical advice or a professional recommendation. Always consult with a qualified healthcare provider for diagnosis and treatment. Refer to the latest local and national guidelines for clinical practice.

References

Takashima H et al. Attenuated Toxicity and Antitoxic Mechanism via Sodium Iodide Symporter Inhibition-Based Tumor-Selective Delivery in Astatine-211 Radioimmunotherapy. Mol Pharm. 2026 Mar 01. doi: 10.1021/acs.molpharmaceut.5c01438. PMID: 41764644.