Good prospects for drug/radiation combo
It was a mistery: Why didn't drugs which boost the tumor-killing power of immune cells in lab do well in clincal trials? Now researchers from Rockefeller University describe a way to enhance the ability of these drugs by combining them with radiation therapy.
Drug/radiation combo may help shrink established tumours.
The immune system’s tumor-fighting T cells work best when maximally activated. Scientists have achieved this by blocking molecules that dampen the cells’ activation, or by removing a population of regulatory T cells that block killing ability of tumor-specific T cells. But neither approach has worked well in patients with established tumors.
Combining these two approaches, a new study published online on August 25th in the Journal of Experimental Medicine, caused small tumors to shrink but had no effect on large tumors. This finding suggested that some quality of large tumors makes them resistant to T cell killing.
Indeed, blood vessels around large tumors lacked proteins required for killer T cells to crawl out of the circulation and into the tumor. Combining the T cell-boosting treatment with radiation therapy – which has been shown to increase the expression of these vessel proteins – was effective in shrinking also large tumors. It remains to be seen whether combining radiation therapy with T cell-boosting drugs will be effective in humans.
26.08.2008
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