KJ-103

KJ-103 refers to two distinct investigational drugs in development by different companies for unrelated indications: 1. **KisoJi Biotechnology's KJ-103** is a first-in-class, naked (unconjugated) humanized monoclonal antibody targeting TROP2 (trophoblast cell surface antigen 2). Unlike antibody-drug conjugates (ADCs), this antibody does not carry a cytotoxic payload but instead recruits immune cells—particularly macrophages—to induce phagocytosis and destruction of TROP2-expressing tumor cells. It binds to a unique epitope on TROP2, distinct from current ADCs, and is being developed as an immunotherapy for solid tumors expressing TROP2, such as colorectal, head and neck, ovarian, breast, bladder, and lung cancers[1][3][5][6]. The drug is currently in preclinical/early clinical development with Cancer Research UK. 2. **Shanghai Bao Pharmaceuticals' KJ-103 (Ricefidase)** is a recombinant IgG-degrading enzyme derived from Streptococcus equi. This endopeptidase cleaves human immunoglobulin G (IgG) antibodies in blood and tissues to inhibit pathogenic IgG-mediated immune responses. It is being developed for the treatment of autoimmune diseases such as anti-glomerular basement membrane disease (Goodpasture syndrome), desensitization prior to kidney transplantation in highly sensitized patients, general immunosuppression settings, and potentially other autoimmune disorders[4][7][9]. Clinical trials have reached Phase II/III for some indications. **Note:** These are entirely separate drugs sharing the same code name but differing completely in structure, mechanism of action, developer/manufacturer company, modality/classification category(s), route of administration(s), target indication(s), and clinical status.

Other names

Ricefidase