Dose-Dependent Cytotoxic Profiling of Astatine-211 for Targeted Alpha Therapy

Alpha particle therapy represents a promising cancer treatment approach, although the fundamental biological effects of alpha irradiation remain poorly characterized. We investigated in vitro cytotoxic effects of free astatine-211 (²¹¹At) using cell viability and proliferation assays across multiple cancer cell lines (LLC, HeLa, and AD293). The results demonstrated dose- and time-dependent cytotoxic effects, with IC₅₀ values between 0.125–0.25 MBq/mL for all cell lines after 72-hour exposure. Proliferation assays revealed that ²¹¹At progressively inhibited cell division in a dose-dependent manner, with complete cell cycle arrest at 0.25 MBq/mL. These findings establish quantitative methodologies for evaluating ²¹¹At-mediated α-particle cytotoxicity and suggest threshold-dependent cellular responses warranting further investigation.