The laboratory and animal study suggests that the substance interleukin 21 (IL-21) might improve the effectiveness of the drug Herceptin. The findings suggest that this happens because the IL-21 boosts the cancer-killing activity of immune cells called natural killer (NK) cells, which attack the tumor.
The findings by researchers at the Ohio State University Comprehensive Cancer Center Arthur G. James Cancer Hospital and Richard J. Solove Research Institute are published in the July 1 issue of The Journal of Immunology. The researchers hope to begin a clinical trial to test the strategy in humans soon.
Herceptin is used to treat HER2-positive breast cancer -- about 20 percent of all breast-cancer cases. HER2 breast cancers have a protein called HER2 on the surface of the tumor cells. Herceptin attaches to the HER2 protein and coats the cells.
The findings indicate that IL-21 stimulates NK cells to attack and destroy the Herceptin-coated cells.
"Only 25 to 35 percent of patients with this form of breast cancer respond to Herceptin," says principal investigator William E. Carson, III, associate professor of surgery and associate director for clinical research at the OSU Comprehensive Cancer Center .
"Our results suggest that giving IL-21 along with the Herceptin might increase the patient's immune response to the tumor and perhaps boost the drug's effectiveness."
Many researchers believe that Herceptin works because it stops tumor cells from growing and causes them to self-destruct through a natural process called programmed cell death, explains first author Julie M. Roda, a graduate research associate in Carson 's laboratory.