Abstract 480: Nanotherapeutic strategies to improve targeted radionuclide therapy

Abstract Cancer is a leading cause of death worldwide. Several multidisciplinary approaches exist for cancer treatment, including radiotherapy and chemotherapy. Radiotherapy uses high-energy radiation to kill cancer cells; chemotherapy inhibits cancer cell proliferation and often kills cells by targeting the cell cycle. Resistance to radiotherapy and chemotherapy is a key determining factor in the outcome of therapeutic efficacy. Conventional nontargeted radiotherapy also affects distant nonirradiated cells, leading to DNA damage and changes in the cell cycle that are often linked to secondary carcinogenesis in patients. In recent years, targeted radionuclide therapy (TRT) has emerged as a promising personalized treatment strategy that delivers cytotoxic levels of radiation directly and specifically to cancer cells. Among radioisotopes, 225Ac exhibits desirable properties for TRT: multiple α-particle emission and high cytotoxicity. One of the challenges with 225Ac is the nonspecific toxicity caused by the release and relocation of its decay daughters. Different approaches have been proposed to prevent the relocation of decay daughters, including nanoparticles. Nanoparticles have been pursued as a promising delivery vehicle of α-emitting radioisotopes to the tumor site. Here, we show specific targeting of Her2-positive breast cancer cells with 225Ac-radiolabeled lanthanum orthovanadate (LaVO4) nanoparticles. Nanoparticles’ surfaces were functionalized to improve biocompatibility and conjugated to target cancer cells, respectively. Cellular uptake and localization of these engineered nanoparticles were analyzed by a Confocal microscope and IncuCyte live cell analysis system. Results confirm its localization in the nucleus following the endolysosomal path, enhancing the nanoparticles’ effectiveness as a delivery vehicle for α-emitting radioisotopes with the potential of increased treatment efficacy. Upon addition of cancer-targeting ligands, these nanoparticles can achieve higher efficiency by delivering the radioisotope to the tumor cells with a potential of safe encapsulation of all α-emitters in the decay chain. The anticancer efficiency of 225Ac-radiolabeled nanoparticles was demonstrated by a dose-dependent effective killing of 3D breast cancer spheroids using both IncuCyte live imaging and the cell survival assays. Ultimately, the results of this study will be crucial in determining the future use of targeted radiolabeled nanoparticle-based delivery systems as an approach for more efficacious cancer treatment. Citation Format: Debjani Pal, Miguel Toro Gonzáleza, Amber N. Bibleb, Brian Sanders, Anna Plechaty, Owee Kirpekar, Mircea Podar, Sandra M. Davern. Nanotherapeutic strategies to improve targeted radionuclide therapy abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 480.