The multi-center first-user study to investigate the safety, tolerance and effectiveness of the bispecific PSMAxCD3 antibody CC-1 in patients with prostate cancer is being carried out at University Hospital Tübingen in its Clinical Collaboration Unit Translational Immunology, and at other DKTK sites in Germany.

Bispecific antibodies are protein molecules with two different binding sites. In the case of the bispecific PSMAxCD3 antibody CC-1, one binding site addresses the prostate-specific membrane antigen (PSMA), which presents on the surface of aggressive prostate cancer cells. The other arm binds to a protein that is responsible for activating defense cells called T cells. When the antibody binds to the two binding sites, it activates the body’s immune response. In addition, CC-1 has a special characteristic: it also binds to the tumor’s blood vessels, creating a dual anti-tumor effect.

A serious side effect of the bispecific antibodies currently available is excessive activation of the immune system. This causes cytokine release syndrome (CRS). CRS can lead to a wide range of symptoms, including in particular fever and cardiovascular problems. When CRS occurs, the patient is usually treated with tocilizumab, an antibody that lessens the excessive immune system response.

For the study, the CC-1 antibody was optimized to minimize the risk of an unwanted immune activation. In addition, patients participating in the trial are given tocilizumab as a preventative measure to start with, in order to prevent CRS occurring in the first place.