225Ac-RAX104

225Ac-RAX104 is a next-generation radioligand therapy (RLT) developed by RadAlliance Therapeutics, specifically optimized for use with the alpha-emitting radionuclide actinium-225 (225Ac). It targets the prostate-specific membrane antigen (PSMA), which is highly overexpressed in prostate cancer cells. The RAX104 ligand was rationally designed to exhibit significantly higher affinity for PSMA and slower dissociation kinetics compared to established ligands like PSMA-617, thereby enhancing tumor retention and aligning with the 9.92-day physical half-life of 225Ac. Preclinical data presented at AACR 2026 demonstrated that 225Ac-RAX104 achieves superior tumor-absorbed activity and potent antitumor efficacy at one-fifth the dose of 225Ac-PSMA-617 in xenograft models. The drug is primarily being developed for the treatment of metastatic castration-resistant prostate cancer (mCRPC).