New drugs improve the success of organ transplants
Monoclonal antibodies can significantly reduce the extent of organ transplant rejection. The molecules act as immunosuppressors. A major problem with a transplant is the rejection mechanisms that our immune system has at its disposal. It recognizes the new organ as foreign and defends itself. In order to avoid this, the immune system is suppressed with medication - doctors speak of "immunosuppression". Patients often have to be treated with such drugs for the rest of their lives. The following always applies: administer as many of the corresponding therapeutic agents as necessary to prevent acute rejection; but also as little as possible in order to avoid side effects and not to open the floodgates to infections. Science was still a long way from such an “ideal” middle ground.
Privatdozent Dr. Bjoern Nashan and his working group from the Clinic for Abdominal and Transplantation Surgery at Hannover Medical School (MHH) played a key role in the development of new drugs that switch off a small part of the body's defenses, which is crucial in the case of a transplant. The following is decisive: So-called T-lymphocytes are primarily responsible for the rejection, they belong to the group of white blood cells. On the surface of the T-lymphocytes are receptors that are stimulated by interleukin 2, a messenger substance of these cells, and stimulated to proliferate. In the course of a rejection reaction, more and more interleukin 2 is formed and more and more receptors are formed. What follows is a cycle in the sense of uninterrupted "self-stimulation": fatal for the patient. The scientists are now investigating monoclonal antibodies that bind specifically to this type of receptor. Result: The receptors are blocked, the T-lymphocytes cannot receive any further signals, part of the defense system is switched off, rejection is made more difficult.
The monoclonal antibodies - they are two different ones - have already been used in international clinical studies led by the MHH in around 500 patients in the early phase after a kidney transplant. The results have exceeded expectations. Significantly fewer rejection reactions occurred: only half as many patients lost their transplant without an increase in infections being observed at the same time and without the otherwise feared side effects occurring. In summary, it can be stated that with the newly developed antibodies, a significant step has been taken towards more specific, more effective and at the same time better tolerated immunosuppression.