Flagship Pioneering launched Serif Biomedicines with a modified DNA platform intended to combine features of gene therapy, mRNA, and siRNA while aiming to improve durability and re-dosing. The startup said its treatments use a DNA instruction component paired with mRNA co-factors delivered via lipid nanoparticles to support durable therapeutic protein expression without editing a patient’s genome. Serif debuted with reported backing and plans to generate preclinical data for investors and partners, with an initial focus on rare genetic diseases and immunology. The company positioned modified DNA as a “new class” of programmable genetic medicines with scalable manufacturing characteristics and lower complexity than viral approaches. The launch reflects ongoing investor appetite for platform strategies that address recurring bottlenecks in genetic medicine, particularly delivery, durability, and redosing constraints.