225Ac-P1B7

225Ac-P1B7 is an experimental radiopharmaceutical consisting of the P1B7 monoclonal antibody labeled with the alpha-emitting radioisotope Actinium-225. P1B7 is a "hapten-directed" antibody specifically engineered to recognize the complex formed when the covalent KRAS G12C inhibitor sotorasib binds to the mutant KRAS G12C protein. This drug-modified protein is subsequently processed and presented as a "haptenated" peptide on Major Histocompatibility Complex class I (MHC I) molecules at the cell surface. By targeting this unique composite epitope, 225Ac-P1B7 allows for the selective delivery of high-energy alpha particles to KRAS G12C-mutant tumor cells that have been pre-treated with sotorasib. This approach effectively repurposes an intracellular oncoprotein inhibitor as a targetable surface antigen to overcome resistance and enhance therapeutic efficacy. The drug was developed by researchers at the University of California, San Francisco (UCSF) and is being explored for the treatment of KRAS G12C-mutant solid tumors.

Other names

Actinium-225 labeled P1B7 IgGActinium225 labeled P1B7 IgGActinium 225 labeled P1B7 IgG225Ac-P1B7 IgG