Complement decay-accelerating factor (CD55) cancer-specific isoform (CD55)

Complement decay-accelerating factor (CD55), also known as DAF, is a GPI-anchored membrane glycoprotein that protects host cells from complement-mediated damage by accelerating the decay of C3 and C5 convertases (UniProt P08174). The PAT-SC1 cancer-specific isoform refers to a unique glycoform or conformational variant of CD55 that is specifically expressed on the surface of gastric cancer cells but is virtually absent from normal gastric mucosa and other healthy tissues (Hensel et al., 1999, Cancer Research). This isoform was identified as the target of the human monoclonal antibody SC-1 (also known as PAT-SC1), which was originally derived from a gastric cancer patient (Vollmers et al., 1995, Cancer Research). When the SC-1 antibody binds to this cancer-specific CD55 epitope, it triggers a signal transduction cascade that leads to the induction of rapid apoptosis in the tumor cells, independent of complement activation (Hensel et al., 2001, Int J Cancer). Additionally, by binding to CD55, the antibody may block its regulatory function, thereby sensitizing the cancer cells to the body's natural complement-mediated immune response. This high degree of tumor specificity makes the CD55 PAT-SC1 isoform a promising target for selective cancer immunotherapy, particularly in gastric malignancies (Patrys Limited).

Other names

Decay-accelerating factorDAFSC-1 antigenPAT-SC1 targetCD55 cancer-associated glycoform

The SC-1 antibody binds to the cancer-specific CD55 isoform, leading to receptor cross-linking that triggers an apoptotic signaling cascade and simultaneously inhibits the protein's ability to protect the cell from complement-mediated lysis.