Chung Lee, John T. Grayhack, M.D., Professor of Urology at Northwestern University Feinberg School of Medicine, and his laboratory group described the adoptive transfer gene therapy technique in the March issue of Cancer Research.
Lee is also a researcher at The Robert H. Lurie Comprehensive Cancer Center of Northwestern University. The researchers first rendered immune cells known as CD8+ T cells insensitive to transforming growth factor beta (TGF-beta), a powerful, naturally occurring substance in the body that enables cancer cells to evade surveillance by the body's immune system. The immunosuppressive effect of TGF-beta in cancer progression is well established.
After inserting a mutated form of the TGF-beta receptor into CD8+ T cells, Lee and associates transplanted the tumor-specific immune cells into mice that had been given a particularly aggressive form of prostate cancer, called TRAMP-C2.
TRAMP-C2 prostate cancer cells produce large amounts of TGF-beta, and possess such potent immunosuppressive power that regular CD8+ T cells are unable to infiltrate tumor tissues, Lee explained.
The mice received a single injection of tumor-reactive TGF-beta-insensitive CD8+ T cells, tumor-specific TGF-beta-sensitive CD8+ T cells or untreated CD8+ T cells at three (early cancer), seven or 21 days (advanced cancer) after they had been injected with the prostate cancer cells.
Lee and co-researchers found that the tumor-reactive TGF-beta-insensitive CD8+ T cells infiltrated prostate cancer tumors and effectively destroyed the TRAMP-C2 cells.