Prostate Specific Antigen Epitope Raises Hopes For Cancer Vaccine.(Brief Article)

2002 FEB 13 - (NewsRx.com & NewsRx.net) -- by Sonia Nichols, senior medical writer - A group at the U.S. National Institutes of Health (NIH) has created an agonist epitope for prostate specific antigen, raising hopes that a vaccine for prostate cancer could soon be over the horizon.

According to H. Terasawa and colleagues at the NIH's Center for Cancer Research, agonist epitopes can do what existing antigens cannot, provide more stimulus to the immune system. Their anticipation is that the new epitope for prostate-specific antigen (PSA), which has yielded good results in the lab and in animal model studies, could be used in peptide- and vector-mediated treatment strategies directed towards prostate cancer.

The group calls the agonist epitope PSA-3A, with the "A" standing for agonist. "Studies demonstrated that when compared with the native PSA-3 epitope, the PSA-3A agonist demonstrated enhanced binding to the MHC class I A2 allele as well as enhanced stability of the peptide-MHC complex," Terasawa and coauthors described in Clinical Cancer Research.

Also, T-cell lytic activity against targets pulsed with PSA-3A was greater than activity against targets pulsed with the native peptide.

When dendritic cells were pulsed with PSA-A3, T-cell stimulation yielded more interferon (IFN)-(gamma) production, and apoptosis in PSA-A3 stimulated T cells remained the same as in T cells stimulated with PSA-3.

T cells created in response to PSA-3A stimulus attacked human prostate cancer cells that expressed PSA, a good sign of the ...