Novel Immune Biomarker | Prostate Cancer

Being also involved in cancer immunology, this article from Mayo Clinic published in Cancer Research last week, is of great interest for me – researchers for the first time have identified immune molecule B7-H3 as a biomarker, that appears to play a role in prostate cancer development and in predicting cancer recurrence and progression after surgery.

This study demonstrate that nearly all normal, pre-malignant and cancerous prostate cells have B7-H3 on their surface. Unlike PSA, B7-H3 stays attached to the surface of prostate cancer cells and does not appear to migrate, thus making B7-H3 a particularly attractive target for therapy. The researchers believe that B7-H3 kills or paralyzes immune cells that are trying to attack the cancer. Their findings indicate that B7-H3 may prove useful as a diagnostic, prognostic and even therapeutic tool because it is stably or increasingly displayed by tumor cells as prostate cancers develop — even after initiation of anti-hormone therapy, which is the most common treatment for advanced prostate cancer, says EurekaAlerts.

The physician-research team examined tissue from 338 consecutive patients who had cancers confined to the prostate and were treated exclusively with a radical prostatectomy (surgery to remove the prostate) between 1995 and 1998. All tumors and precancerous tissues displayed B7-H3, but patients with the highest levels of B7-H3 within their prostate tumors (19.8 percent) were four times more likely to experience cancer progression compared to those with weak levels of B7-H3 within their tumors. Moderate levels of B7-H3 also correlated with a slightly higher risk of recurrence (35 percent) (via).

B7-H3, a member of the B7 family of the Ig superfamily proteins, is expressed on the surface of the antigen-presenting cells and down-regulates T cell functions by engaging an unknown counterreceptor on T cells [ref.]. Mayo Clinic Cancer Center was the first to discover the B7-H family of immune molecules in 2001. They showed that B7-H3 and other members of the B7-H family, such as B7-H1, can have an inhibitory function and actually protect cancers as they develop [via].

To understand how B7-H3 affects the immune system, and whether a mutation of B7-H3 is involved in the anti-immune activity, more research is necessary. Mayo is planning clinical trials for a number of cancers in late 2008, and researchers are currently developing the necessary therapeutic antibodies to be used in these studies. Investigators expect that clinical laboratory tests for the B7-H proteins may become available at Mayo to assist with the assessment of patients with kidney cancer by late 2007 or early 2008, and then for prostate cancer patients shortly thereafter [ref.] .

Well, B7-H3 molecule is already patented (what a shame!) not only by Mayo, who already holds patents to B7-H1, B7-B4 (check it here) and has licensed the patent rights to Medarex, Inc., but also by pharmaceutical company Wyeth for use as immunoregulatory agent (here it is). In addition, Mayo Clinic has filed a patent application related to B7-H3. Drs. E. Kwon, T. Roth and Y. Sheinin and Mses. C. Lohse and S. Kuntz are inventors of this technology. Track it further on PatentLens or Google Patent Search.

(photo source: B7-H3 immunohistochemistry)