Crefmirlimab is an investigational humanized mini-antibody or antibody fragment engineered for specificity toward CD8. This design implies a focus on modulating the function or activity of CD8+ T cells, a critical population of cytotoxic lymphocytes in the immune system. Such a molecule is likely being developed as an immunomodulatory therapy, potentially for applications in oncology (e.g., to enhance anti-tumor T-cell responses) or in autoimmune diseases (e.g., to selectively deplete or inhibit pathogenic CD8+ T cells). Its "mini-antibody" format may offer advantages in tissue penetration and pharmacokinetics compared to full-length antibodies.