If the substance proves suitable, the scientists would like to use it to predict the efficacy of chemotherapy in the future. They primarily have a new generation of cancer medication in mind that also binds to the folic acid receptor, which then channels the drug into the cancer cells, where it unfolds its therapeutic effect.
"Our PET tracer provides important additional information for this targeted therapeutic approach with cytotoxic substances," says Ametamey. After all, one difficulty with the new form of therapy is that not in all patients the cancer cells carry the folic acid receptor. In the case of ovarian, cervical and brain tumours, it is nine out of ten patients, with lung cancer around three quarters and with breast cancer about half. In patients without the receptor, the novel chemotherapy is ineffective.
With the aid of the new technique, it could be possible to predict whether a patient will respond to such treatment. Patients whose tumours do not have any folic acid receptors could be spared this therapy and its side effects. Moreover, physicians can use the new PET tracer to better monitor the progress of the therapy and study whether the tumour is shrinking.
Making inflammations visible
However, the new PET tracer is not just interesting for cancer medicine, but also just the ticket for displaying inflammatory responses in the body. After all, the folic acid receptor occurs also at the surface of certain cells of the immune system, the macrophages, and only if these are in a so-called activated state during an inflammatory response. The new marker substance could thus be used to display inflammatory diseases such as arteriosclerosis, arthritis or inflammatory bowel diseases with PET.
Moreover, a third area of application is also imaginable for the substance: medication development. "If we've got a method to detect chronic inflammatory responses in a non-
|Contact: Roger Schibli|