RegCell, the nearly 50-year project of Shimon Sakaguchi’s regulatory T cell research lineage, raised a $44 million Series A as it prepares to advance Tregs into clinical development. The financing positions the decade-old biotech to translate regulatory T cell biology into clinical programs, leveraging its scientific heritage anchored by the Nobel laureate’s work on how immune systems maintain self-tolerance. In the competitive immunotherapy landscape, Treg-focused approaches face a high bar for durable safety and efficacy, making a sizable Series A a signal that investors see investable clinical risk as the pipeline matures.