Melanoma Vaccine Successes
Scientists are slowly moving towards vaccine therapies for "black skin cancer" using different methods. Modified proteins or cells trained for tumors trigger the immune system to fight the cancer. The US pioneer Steven Rosenberg from the National Cancer Institute and Dirk Schadendorf from the hospital in Mannheim publish positive results in the treatment of patients with advanced melanoma in the March issue of the scientific journal Nature Medicine. They shrank the tumors in some of the patients, and in two cases even made them disappear.
Steven Rosenberg tried years ago to treat melanoma patients by administering the immune messenger substance interleukin-2. At that time, however, the most serious side effects occurred due to the high dosage of the substance.
In the new study, a modified protein from melanoma cells - glycoprotein 100 (gp100) - was used as a vaccine as a substance to induce an immune response against the cancer tumor after vaccination. The synthetically produced protein was "designed" in such a way that it elicited a particularly strong defense reaction by cell-killing lymphocytes (CTL).
The 31 treated patients all had advanced melanoma with metastases. Long-term survival rates are low here, while more than 80 percent of patients can be cured with early-stage surgery (tumor thickness less than 0.75 millimeters). With the vaccine and IL-2, Rosenberg and his team were able to induce tumor shrinkage in 42 percent of patients receiving the treatment. Only 17 percent were able to do this with interleukin-2 alone.
Dirk Schadendorf from the University of Heidelberg, Klinikum Mannheim, and his co-authors tested another and possibly even more sophisticated method on 16 patients. They used a vaccine made from "dendritic cells" obtained from the seriously ill with at least three months left to live.
The background: Dendritic cells use their "tentacles" to grab foreign substances that penetrate the skin, migrate to the nearest lymph nodes and then ideally present them to the immune system so that it develops a defense reaction. In the laboratory, Schadendorf and his team loaded the dendritic cells taken from the patient's blood with a cocktail of melanoma components and then injected them directly into the patient's lymph nodes.
The patients initially received four such vaccinations within a month, the fifth immunization after a further two weeks. Then immunization was carried out every month up to a total of ten such procedures.
The result: In 31 percent of the patients, there was an objective shrinkage of the melanoma. In two of them, the melanoma went away altogether - and didn't come back within a year.
The positive results are by no means proof of the effectiveness of the melanoma vaccine. The number of patients included in the studies is far too small for this. In addition, it must first be clarified which type of immunization is the best. Both studies are just early attempts. The results of a study with a melanoma vaccine produced in Vienna have not yet been published.
