FOLR1-targeted actinium-225–based alpha-particle therapy eliminates ovarian cancer

Despite the advancement in therapies, ovarian cancer treatment is challenging because of poor prognosis and high relapse associated with acquired resistance. Emerging targeted alpha particles, particularly actinium-225 ( ²²⁵ Ac), for treating refractory cancers have opened avenues for improved therapeutic options. Here, we describe a successful example of folate receptor 1 (FOLR1)–targeted ²²⁵ Ac alpha-particle therapy for treatment of ovarian cancer. Longitudinal positron emission tomography imaging demonstrated high tumor-specific uptake of αFOLR1 (anti-FOLR1 antibody) in SKOV3 xenografts. FOLR1-targeted ²²⁵ Ac demonstrated high therapeutic efficacy, achieving marked tumor regression, 80% survival, and 40% complete tumor elimination. The therapy resulted in tumor-specific double-stranded DNA damage, and no obvious toxicity was observed in normal tissues. Estimated human dosimetry showed high absorbed dose for tumor and minimal absorbed dose for healthy tissues, establishing its safety. In totality, FOLR1-targeted ²²⁵ Ac alpha-particle therapy is an efficacious and safe treatment with high feasibility for clinical translation to fight against ovarian cancer.