A new cancer treatment called RYZ101 has shown promising results in a clinical trial for patients with advanced neuroendocrine tumors (NETs). The treatment, developed by RayzeBio (a part of Bristol Myers Squibb), targets tumors that have receptors for somatostatin, a natural hormone. In the Phase III ACTION-1 trial, RYZ101 significantly delayed the time until the cancer worsened compared to standard treatments, such as long-acting somatostatin analogues, everolimus, or sunitinib. This is the first time an alpha-particle-based radiopharmaceutical therapy has been tested in this way. RYZ101 combines a molecule called DOTATATE with the radioactive isotope Actinium-225, which delivers targeted radiation to cancer cells. The study focused on patients with advanced gastroenteropancreatic neuroendocrine tumors (GEP-NETs) who had already received a similar but different treatment called Lu177-based therapy, which is a beta-particle-based radiopharmaceutical. Unfortunately, many patients do not respond well or stop responding to Lu177-based therapy over time. Dr. Amreen Husain, Chief Medical Officer of RayzeBio, said, “The improvement in progression-free survival is a defining moment for RYZ101 and for the patients we built this programme around. These are people with advanced GEP-NETs whose cancer has progressed after Lu177-based therapy and have few remaining options.” Dr. Simron Singh, a medical oncologist at the University of Toronto and the lead researcher of the ACTION-1 study, added, “Lu177-based therapy is widely used in GEP-NETs, but unfortunately, the vast majority of patients will eventually progress.” The trial is still ongoing, and researchers are continuing to collect data to determine if RYZ101 also improves overall survival. Detailed results will be shared at a future medical conference. Additionally, RYZ101 is being studied for its potential use in another type of cancer called hormone receptor-positive metastatic breast cancer.