Actinium Pharmaceuticals Presents New Radiochemistry Data at SNMMI 2026 Demonstrating That CAR Optimization Improves Tumor Targeting and Pharmacokinetics of Actinium-225 Radioconjugates

Optimization of chelator-to-antibody ratio (CAR) is a key design parameter for next-generation radioconjugates, presenting tunable levers Actinium is utilizing to engineer more effective drug candidates Optimized CAR improved tumor targeting, internalization, and pharmacokinetics of 225Ac-labeled antibodies Lower-CAR conjugates preserved tumor targeting while reducing off-target liver and spleen uptake, supporting a wider therapeutic window that may enable higher, safer dosing Findings reinforce Actinium's proprietary radiochemistry expertise and directly support the Company's broader radioconjugate pipeline a capability that applies to every program from the platform NEW YORK, June 1, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, on May 31, 2026 presented new radiochemistry data at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting taking place in Los Angeles, California. The poster presented a systematic evaluation of chelator-to-antibody ratio (CAR) optimization for Actinium-225 (225Ac)-labeled antibody radioconjugates, a critical but often underappreciated design parameter that directly influences radiolabeling efficiency, antigen binding, internalization, and biodistribution.