OX40 (CD134, TNRSF4), like DR5 and GITR, is a member of the TNF receptor superfamily. Similar to other members of the TNF receptor superfamily, strong OX40 immunologic activity requires that three OX40 proteins on the surface of a T cell be bound together by an OX40 ligand or an antibody. In the case of OX40, binding three or more OX40 proteins with an IgM antibody sends a strong T cell immune stimulatory signal.

We anticipate that the multivalent binding provided by an IgM anti-OX40 agonist antibody may produce a stronger immuno-oncology biological signal, as compared with a comparable IgG anti-OX40 agonist antibody.

An IgM anti-OX40 antibody induces more immune stimulatory signaling as compared to a comparable IgG anti-OX40 antibody.

OX40 is considered to be a potentially important immuno-oncology target for both solid and blood cell tumors. We hope to develop an anti-OX40 IgM agonist antibody which is substantially more effective than IgG anti-OX40 agonist antibodies at inducing an effective immune response for the treatment of solid and blood cell tumors.