Combination Treatment Shrinks Tumors?
Reported August 26, 2008
(Ivanhoe Newswire) — A one-two punch may be the best way to shrink tumors.
A new study may help explain why anti-cancer drugs, which boost the tumor-killing power of immune cells, havent done well in clinical trials. The report shows a way to enhance how these drugs shrink well-established tumors.
The immune systems tumor-fighting T cells work best when they are activated to their maximum. This happens by blocking molecules that dampen the cells activation, or by removing some regulatory T cells that stop the killing ability of tumor-specific T cells. However, these approaches havent worked well in patients with established tumors.
The new research shows combining these two techniques in mice shrank small tumors but had no effect on large ones. This suggests the quality of some large tumors makes them resistant to T cell killing. Data shows the blood vessels around large tumors dont have the proteins required for killer T cells to get out of the circulation and into the tumor.
Researchers say combining the T cell-boosting treatment with radiation therapy — which can increase the expression of these vessel proteins — shrank large tumors. However, it is still not known whether this combination will work in humans.
SOURCE: Journal of Experimental Medicine, published online August 25, 2008