Zorglub writes "Two prostate cancer patients who had been told their condition was inoperable are now cancer-free as the result of an experimental therapy, the Mayo Clinic in Rochester announced Friday. 'Cancer has a propensity for turning off T cells. Dr. Allison hypothesized that if you block the off-switch, T cells will stay turned on and create a prolonged immune response. Dr. Kwon, then at NIH, demonstrated that CTLA-4 blockage could be used to treat aggressive forms of prostate cancer in mice. There was one limitation to that concept — the worry that by simply leaving all the T cells on there may not be enough response aimed at the tumor. Dr. Kwon called Dr. Allison and designed the trial together. The idea: use androgen ablation or hormone therapy to ignite an immune approach — a pilot light — and then, after a short interval of hormone therapy, introduce an anti-CTLA-4 antibody that acts like gasoline to this pilot light and overwhelms the cancer cells.' After the treatment, the patients' tumors shrunk to such a degree that they could be successfully removed."