Researchers identify molecule that promotes growth of RCC

Mayo Clinic researchers say they have identified a molecule known as B7-H4 that blocks the immune system, thereby helping renal cell carcinoma grow and metastasize.

Researchers examined 250 fresh-frozen tumor specimens removed from patients with RCC, then sorted the tumors by those that showed B7-H4 and those that did not. When comparing clinical and laboratory data, a pattern emerged that associated active B7-H4 with fatal, metastatic cancers, compared with tumors lacking H7-B4.

Patients with RCC are three times as likely to die from cancer if their B7-H4 is active than those whose tumors do not express the molecule. Patients with RCC tumors expressing both B7-H4 and B7-H1, another member of the B7 family of molecules, pose an even greater risk of death than those with tumors that express one or the other alone.

The study appears in the Proceedings of the National Academy of Sciences (2006; 103:10391-6).

“Based on these findings, we conclude that B7-H4 has the potential to be a useful prognostic biomarker for patients with RCC,” said first author Amy Krambeck, MD, of the Mayo Clinic, Rochester, MN. “In addition, B7-H4 represents a new target to attack tumor cells as well as tumor vessels, thus improving treatment options for patients with RCC.”