Laboratory / Animal / Preclinical Studies
By incorporating PC-SPES into the rat diet, researchers conducting an in vivo study showed antitumor effects using a Dunning R3327 rat prostate cancer model. Levels of 0.05% and 0.025% of dietary PC-SPES were fed to the rats over a 6-week period. No toxicity was seen, nor was there a difference in the food intake of the rats during this time. Pulmonary tumors were induced by intradermal injections of MAT-LyLu cells, which are particularly resistant to many forms of treatment. Tumor incidence was inhibited in a dose-dependent manner, and the rate of tumor growth showed the same dose-dependent response.[8,9]
In another study, which used male BNX nu/nu immunodeficient nude mice, PC-SPES was also administered orally, but in suspension. The mice received 300 rad of whole-body irradiation, after which they were inoculated with either PC-3 or DU-145 prostate cancer cell lines. Treatment with PC-SPES began the day after injection. Results showed that PC-SPES suppressed the growth of DU-145 tumors compared with tumor growth in the control group. Cytological analysis showed apoptosis in the treated group that was not apparent in the control group.
In two other studies, clinical studies of patients were initiated along with in vitro and in vivo research. The results of these two patient groups are discussed in the Human/Clinical Trials section of this summary. The first study, preceding more extensive research, examined in vitro activity of PC-SPES against LNCaP, LNCaP-bcl-2, PC-3, and DU-145 cells lines. Results showed that PC-SPES was active in suppressing both hormone -sensitive and hormone-insensitive prostate cancer cell lines. In the subsequent study, research was conducted in vitro on the ability of PC-SPES to induce apoptosis in androgen-independent (AI) prostate cancer cell lines, and in vivo on the effect of oral PC-SPES on the growth of xenografted PC-3 tumors in immunodeficient male mice. Mice in the treatment arm—in which treatment was started 1 week after implantation—showed a significant decrease in tumor weight when compared with mice in the control arm. PC-SPES showed activity against both androgen -sensitive and AI prostate cancer in the patients and suppressed tumor growth in AI tumors in mice. Reviewed in [10,11,12] In both studies, the patients were given capsules manufactured between 1996 and 1999, a time when contamination levels of DES were highest.