Bispecific antibody to be tested for treatment of prostate cancer

Bispecific antibodies are proteins with two different binding sites. The bispecific PSMAxCD3 antibody CC-1, has one binding site that is directed against the Prostate-Specific Membrane Antigen (PSMA), which is presented on the surface of the malignant cells. With the other binding site, the antibody attaches to a protein that is responsible for activating immune cells – the so-called T cells. The activation of the immune system is only achieved upon binding of the antibody to both binding sites. CC-1 also has another special feature – it binds to the blood vessels of the tumor and therefore mediates a dual anti-tumor effect.

One serious side-effect of so far available bispecific antibodies is an excessive unspecific activation of the immune system, resulting in a  so-called Cytokine Release Syndrome (CRS). If a CRS occurs, a wide variety of signs and symptoms can appear –including particularly high fever and cardiovascular side effects. CRS treatment normally involves Tocilizumab, an antibody that dampens the excessive reaction of the immune system.

“We’ve optimized CC-1 in many aspects in order to prevent an unspecific activation of the immune system as far as possible. We’ll also for the first time administer Tocilizumab as a prophylactic measure in our study to prevent development of CRS in the first place. Altogether, our measures will reduce the side-effects so that really efficient doses can be administered,” says Prof. Gundram Jung, whose academic work for more than thirty years has focused on developing optimized bispecific antibodies.

The clinical development of this therapeutic approach has been possible by the close cooperation between the “Clinical Cooperation Unit Translational Immunology” of the German Cancer Research ¹The German Cancer Research Center (DKFZ) in Heidelberg has a long-term connection as the core center within the DTKT to university partner sites in Germany that specially focus on oncology.

Center –based in the Department of Internal Medicine at the University Hospital Tübingen – and the Department of Immunology at the University of Tübingen.

The innovative phase I study, which will examine the bispecific antibody CC-1 in human beings for the first time, has been enabled by funds from the Helmholtz Validation Fund and the DKTK. Tübingen will administer the antibody as first center, later on many other DKTK centers will participate in the study. “We’re excited that we can offer these patients in a desperate situation a new treatment concept and that we are able to bring such an innovative immunotherapy approach to the clinic. We now want to find out whether we can indeed achieve to specifically activate the patient’s immune system to fight prostate carcinoma and to provide an effective treatment for this disease in the future,” says Prof. Helmut Salih, Principal Investigator of the clinical trial; “furthermore, we’re delighted that the field of drug development is at least partially gained back for public institutions through this study.”

Information on the study

The multi-center first in human study to investigate the safety, tolerability and efficacy of the bispecific PSMAxCD3 antibody CC-1 in patients with prostate carcinoma is being conduced at the University Hospital Tübingen in the Clinical Cooperation Unit for Translational Immunology as well as at other DKTK sites in Germany.

Adult patients with a castration resistant prostate carcinoma, who have already received three previous therapies, will be able to participate in the study.  Further inclusion criteria are for example, an intact function of liver kidneys and the blood-forming system. The antibody is administered as a continuous infusion over a period of seven days. During this time, patients will be hospitalized and closely monitored. Prior to the first antibody infusion, Tocilizumab is administered as prophylactic measure. Regular outpatient check-ups will take place after each treatment cycle. If the patient clinically responds, antibody application can be repeated up to six times.

Doctors (and interested patients) can contact kketi@med.uni-tuebingen.de by email.