MONTREAL, CANADA - If there is a vaccine against cancer thing developers want to know, is why only a handle patients respond strongly to their inventions. Now, during an Immunology meeting here, a team of scientists reported that a group of metastatic melanoma patients may be indicative of a response to this mysterious question.
Cancer vaccines involve the use of immune cells from a patient to initiate an attack against the cancer. Although the results of vaccine trials against cancer have often been disappointing, there is continued interest because the strategy is so logical in theory. Doctors have had the most success with vaccines to treat melanoma, a skin cancer that is often fatal if it spreads.
immunologist Nathan Martinez of the Queensland Institute of Medical Research in Australia and colleagues are testing a vaccine made from patients' dendritic cells, a type of white blood cell that normally triggers an immune response against agents pathogens. Researchers create a custom vaccine for each patient by harvesting and concentration of immune cells. At the annual Federation of Clinical Immunology companies and the annual International Union of Immunology Societies, Martinez reported that 43 patients with advanced melanoma who are receiving vaccines, seven responded completely, their tumors decreases undetectable levels. This low response rate is par for the course in terms of vaccine against cancer. Thus, the Martinez team decided to examine whether the seven wealthy patients have shared something in common.
When they analyzed blood samples of patients taken before vaccination, the researchers found that patients who responded had lower levels of a protein, S100B, compared to those who did not. S100B is normally held inside the cells, but some scientists believe that when tumors develop, healthy cells begin to die and release the protein. Martinez speculates that increased levels of S100B indicate a significant tumor burden - something that can be difficult to measure, and what can a less likely to respond to a vaccine. Equally interesting is another finding: In all stakeholders tested to date, four out of seven cells from samples of pre-vaccine CTL blood could kill the tumor cells of that patient in a petri dish . This was not the case for patients who was not helped by the vaccine.
"I've never seen such a striking correlation," said Lloyd Stoolman, an immunologist at the University of Michigan, Ann Arbor. Although skeptical about the long-term use vaccines of dendritic cells, which he thinks may be less effective than other types, it is the ability to predict success in vaccine trials against cancer is the "Holy Grail" of the field.
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