How Melanoma Hides

Melanoma avoids T cells with B7H1

(RxWiki News) The inflammation response is used by the body to signal an attack, but it turns out in at least one kind of melanoma, the cancer uses the same signal to go into hiding.

Researchers at Johns Hopkins found that 40 percent of their melanoma tissue samples contained the B7-H1 protein, which allows cancer cells to avoid the immune system's cancer killing T cells.

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Scientists observed that when the immune system issues a signal to attack, the melanoma cancer cells increased their production of B7-H1, which effectively hides them from the T cells, the beat cops of the immune system.

Although you would expect that patients with this type of melanoma would have worse life expectancy, that turned out to not be the case. Patients with a B7-H1 containing melanoma had survival rates roughly equal to ordinary melanoma.

Scientists explained the apparent contradiction by arguing that these patients have immune systems that recognize and are actively trying to kill the cancer.

Furthermore, researchers stated that most of the patients in the study had also been in another study that had used drugs to boost the ability of the immune system to recognize and destroy cancer cells.

They acknowledged that this may have altered the results.

The study design analyzed 150 samples from benign melanocytic lesions, malignant and metastatic melanomas. From the 150 samples taken from patients at Johns Hopkins, 57 had strong expression of the B7-H1 protein.

Researchers stated they were working on identifying a cancer drug that could target the B7-H1 protein, and are developing the use of B7-H1 as a screening test in the future.

Results were published online March 28 in the journal Science Translational Medicine.

Funding came in part from the National Cancer Institute, the National Institutes of Health, the Melanoma Research Alliance, the Barney Family Foundation, the Michael Rolfe Foundation for Pancreatic Cancer Research, and the Dermatology Foundation.

Researchers disclosed financial relationships with the pharmaceutical corporation Bristol-Myers Squibb, but Johns Hopkins states that financial conflict of interest is being managed in accordance with university policy.

Review Date: 
April 25, 2012