The Pittsburgh Cancer Institute has started human testing of a treatment that doctors hope will enhance the body's ability to fight cancer and maybe dissolve malignant tumors. Two patients at the center were the first people to receive the treatment, in vitro sensitization or IVS, which previously had been tested only on mice, The Pittsburgh Press reported Sunday. Studies have shown the process fights remaining tumor cells in mice, the newspaper said. In some cases, the animals' cancer has been eliminated entirely. Researchers say it is too soon to tell what effect the treatment has had on the two patients. Their patients' identity and the type of cancer they had were not disclosed. The tests began in June. ``I have no question but that at some point in the intermediate-term future, this will be of therapeutic benefit,'' said Dr. John M. Kirkwood, one of two principal investigators in the study. Dr. Norman Wolmark, the other lead investigator, said the information gathered in the study should be useful in pointing the way even if there is no immediate effect on the two patients' tumors. ``I think the treatment can be modified in the hope that a successful tumor response will result,'' he said. In vitro sensitization involves removing a tumor and irradiating it to inactivate the tumor cells, researchers told The Press. The cells are combined with a bacterium commonly used to vaccinate against tuberculosis in order to stimulate the patient's immune system. The patient then is injected with the irradiated cells to produce sensitized lymphocytes, or cells critical to the body's natural defense against disease and infection, researchers said. Other steps in the complex treatment involve the use of the tumor-fighting hormone interleukin-2. Researchers told the Press it may be two years or more before enough patients are treated for a sufficient amount of time to know the effectiveness of the treatment. The groundwork for the treatment was begun more than five years ago at the National Cancer Institute in Washington by research scientist Suyu Shu. In 1986, Shu moved to the Pittsburgh Cancer Institute, which is affiliated with the University of Pittsburgh, where he continued his laboratory work with mice. He recently left for the University of Michigan. Shu's approach, called adoptive cellular immunotheraphy, is not a widely used approach to cancer research. Most tumors are not recognized or only weakly recognized by the body's immune system and therefore continue growing because the immune system does little to attack them, said Dr. Ronald Herberman, director of the Pittsburgh Cancer Institute. ``This is basically the main reason there has not been great emphasis'' in research to enhance the immune system, he told the newspaper. Herberman said researchers, ideally, would ``like to see some almost immediate shrinkage of the tumor. But it may not happen that way.'' ``It's a tall order to expect this kind of treatment would actually make a large tumor melt away,'' he said.
