DR5 is a member of the tumor necrosis factor receptor superfamily (TNFrSF) and is often expressed on the surface of cancer cells. Strong activation of the DR5 pathway requires multiple receptors to be cross-linked simultaneously by an antibody or other binding agent to create an apoptotic death signal to the cell. Unlike traditional IgG antibodies, IGM 8444 has 10 binding units, giving it an advantage to cross-link multiple DR5 receptors at once, sending a stronger signal to cause cancer cell death.

In addition, the unique natural structure of an IgM antibody may allow us to improve the safety profile of DR5 binding agents by controlling the timing of the apoptotic signal, thereby reducing harmful side effects like liver damage. In our studies, DR5 IgM antibodies have significantly enhanced in vitro killing potency on cancer cells, as compared to IgG antibodies with the same binding units.