RTX-250

RTX-250 is an allogeneic, engineered red blood cell therapeutic (RCT) developed by Rubius Therapeutics for the treatment of solid tumors. Utilizing the company's proprietary RED PLATFORM, RTX-250 was designed to express 4-1BB ligand (4-1BBL) and interleukin-12 (IL-12) on the surface of red blood cells. This dual-signaling approach was intended to stimulate a potent anti-tumor immune response by providing costimulatory signals to T cells and natural killer (NK) cells via the 4-1BB receptor and activating the IL-12 pathway. By tethering these potent immune stimulators to the red cell surface, RTX-250 aimed to provide systemic immune activation while minimizing the toxicities often associated with the systemic administration of recombinant cytokines. Development of the program was halted in 2022 as part of a corporate restructuring, and Rubius Therapeutics subsequently liquidated its assets in 2023.