Effects of a phytotherapeutic agent, PC‐SPES, on prostate cancer: a preliminary investigation on human cell lines and patients

Abstract

To evaluate the in vitro activity of PC-SPES, a complex phytotherapeutic agent, against prostate cancer cell lines, and to assess its activity in suppressing serum prostate specific antigen (PSA) level in patients with prostate cancer. Four variant prostate cancer cell lines (LNCaP and an apoptosis-resistant derivative, LNCaP-bcl-2, PC3 and DU145) were exposed to three different concentrations of PC-SPES extract. Cell viability was measured at 3, 4 and 5 days of exposure using a colorimetric assay and was compared with control cultures receiving aliquots of the ethanolic extraction medium alone. Clinically, a prospective study was initiated in patients with prostate cancer who refused conventional therapy or who had failed previous cryosurgery, radiation therapy and/or hormonal therapy. The patients were treated with PC-SPES (three capsules of 320 mg/day). The serum PSA responses and side-effects were evaluated. All cultured prostate cancer cell lines showed a significant dose-dependent reduction in cellular viability (compared with control cultures) by exposure to 4 and 6 μL of PC-SPES extract/mL of culture medium (Pn=18, P=0.026). The side-effects in these patients were nipple tenderness in two (6%) and leg clots requiring heparinization in two (6%). No gynaecomastia or hot flashes were observed in this group and the treatment was well tolerated. In this preliminary study, an extract of the phytotherapeutic agent PC-SPES was active in suppressing the growth of cultured hormone-sensitive and -insensitive prostate cancer cell lines. In the small clinical study, PC-SPES therapy decreased serum PSA levels in most patients. However, a longer follow-up and more patients will be required to evaluate the long-term efficacy of this new phytotherapy.