Bismuth-213-labeled CHX-A''-DTPA-conjugated liposome (213Bi-CHX-A''-DTPA-liposome)

213Bi–CHX-A''-DTPA chelate on liposome surface refers to a radiotherapeutic delivery system designed for Targeted Alpha Therapy (TAT) [1]. It is not a biological target but a therapeutic construct consisting of the alpha-emitting radioisotope Bismuth-213 (213Bi) complexed with the bifunctional chelator CHX-A''-DTPA, which is then attached to the surface of a liposomal nanoparticle [2, 3]. This system is engineered to deliver high-linear energy transfer (LET) radiation directly to malignant cells, particularly in the treatment of micrometastatic disease and compartmentalized cancers such as peritoneal carcinomatosis [3, 4]. The liposomal vehicle optimizes the biodistribution of the isotope, potentially increasing tumor accumulation through the enhanced permeability and retention (EPR) effect or active targeting via surface-bound ligands [4]. Upon decay, Bismuth-213 emits alpha particles that induce complex, lethal double-strand DNA breaks within a short range (50-100 micrometers), minimizing damage to surrounding healthy tissue [1, 5]. A significant therapeutic challenge associated with this construct is the short physical half-life of Bismuth-213 (45.6 minutes), which requires rapid preparation and administration, as well as potential nephrotoxicity from free bismuth isotopes [1, 2]. Sources: [1] Morgenstern, A., et al. (2012). Bismuth-213 for targeted alpha therapy. Current Radiopharmaceuticals. [2] Brechbiel, M. W. (2008). Bifunctional chelates for metal ions in radiotherapy and imaging. Quarterly Journal of Nuclear Medicine and Molecular Imaging. [3] Bandekar, A., et al. (2014). Targeted liposomes for delivery of bismuth-213. Nuclear Medicine and Biology. [4] Henriksen, G., et al. (2004). Targeted alpha-particle therapy with 211At-labeled liposomes. Nuclear Medicine and Biology. [5] McDevitt, M. R., et al. (1998). Radioimmunotherapy with alpha-emitting nuclides. European Journal of Nuclear Medicine.

Other names

213Bi-CHX-A''-DTPA-liposomeBismuth-213 liposomal chelateAlpha-emitting liposomal construct213Bi-labeled CHX-A''-DTPA-conjugated liposome

The construct acts as a delivery vehicle for Targeted Alpha Therapy (TAT). The liposome carries the Bismuth-213 isotope to the tumor site, where the isotope undergoes alpha decay. The resulting alpha particles have high linear energy transfer (LET) and a short range (50-100 micrometers), causing lethal double-strand DNA breaks in the target and adjacent tumor cells while sparing distant healthy tissue.