- A tumor cell vaccine is an experimental cancer treatment. Cancer cells are collected from a patient and then used to develop a vaccine. The vaccine will produce an immune system response to help destroy other cancer cells in the body. Researchers are studying ways to improve these tumor cell vaccines. One way is to add an adjuvant. An adjuvant is a substance that brings about a stronger immune system response. ISCOMATRIX is an adjuvant that has been used safely in other clinical studies. But it has not been studied with certain tumor cell vaccines. Researchers want to find out whether a tumor cell vaccine with ISCOMATRIX, given along with cancer drug treatment, is a safe and effective way to slow or prevent tumor growth after tumor removal surgery.