Researchers at the University of Bern have developed a therapy option that activates the body's own defense system against melanoma.
Article continues below
Components of a bacterium are embedded in gel and applied directly to the tumor area.
The model showed that the gel reduces tumor growth, inhibits its spread to other organs and thus prolongs survival. In a next step, the gel is to be tested in clinical studies for its effectiveness in patients.
Black skin cancer (melanoma) is a malignant cancer that can be completely removed if diagnosed early with a good chance of a cure. However, the prospects worsen for those affected if, in later stages of the disease, offshoots (metastases) of the tumor also spread to other organs.
In the last ten years it has been shown that spectacular treatment successes are possible by activating one's own immune system with so-called immune checkpoint inhibitors.
"Unfortunately, a good half of all patients do not respond to it," says Prof. Mirjam Schenk from the Institute of Pathology at the University of Bern. Her group is now showing a promising way of fighting melanoma with a new type of hydrogel.
Although it led to a regression of the directly treated local and occasionally also distant skin tumors, it proved to be less effective in those affected with metastases in internal organs and could not significantly improve the survival rate of the affected patients. In addition, this treatment with live bacteria carries a certain risk and is only used in rare cases.
The research group led by Mirjam Schenk has now shown that components of this bacterium in the form of a gel are more effective in controlling tumor growth than the living BCG bacteria previously used. In collaboration with researchers from EPFL and Harbor-UCLA Medical Center (USA), they have developed a novel, heat-sensitive hydrogel that can be administered simply and once.
This hydrogel is liquid at room temperature, but forms a viscous gel at body temperature, which acts as a local depot and continuously releases components of the bacterium. This leads to a sustained activation of the immune system.
In experiments, mice with melanomas showed a significantly longer survival time after treatment with gel.
At the same time, the formation of tumor deposits (metastases) in the lungs was suppressed.
In addition, the researchers were able to demonstrate a qualitatively and quantitatively improved immune response of T cells against melanoma cells in biopsies from melanoma patients after BCG therapy.
They also found a positive correlation between this immune response and improved survival.
According to the researchers, this speaks in favor of clinical application: "Local application of the hydrogel is an effective and safe immunotherapeutic option for reducing the metastasis burden and prolonging the survival of melanoma patients," Schenk is convinced.
In a next step, the gel is to be tested in clinical studies for its effectiveness in patients and compared with therapies that have already been approved.
The project was supported by the Wilhelm Sander Foundation and in part by the Foundation for Experimental Biomedicine Zurich and the Swiss National Science Foundation and was published in the Journal for ImmunoTherapy of Cancer. ■