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

Objectives To evaluate the in vitro activity of PC-SPES, a complex phytothe rapeutic agent, against prostate cancer cell lines, and to assess its activ ity in suppressing serum prostate specific antigen (PSA) level in patients with prostate cancer. Patients and methods 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 meas ured at 3, 4 and 5 days of exposure using a colorimetric assay and was comp ared with control cultures receiving aliquots of the ethanolic extraction m edium alone. Clinically, a prospective study was initiated in patients with prostate cancer who refused conventional therapy or who had failed previou s cryosurgery, radiation therapy and/or hormonal therapy. The patients were treated with PC-SPES (three capsules of 320 mg/day). The serum PSA respons es and side-effects were evaluated. Results All cultured prostate cancer cell lines showed a significant dose-d ependent reduction in cellular viability (compared with control cultures) b y exposure to 4 and 6 mu L of PC-SPES extract/mL of culture medium (P<0.001 ). In contrast to the hormone-insensitive cell lines tested (LNCaP-bcl-2, P C-3 and DU-145), only the hormone-sensitive cell line LNCaP was affected by the lowest dose of PC-SPES extract tested (2 mu L/mL medium). In the prosp ective clinical trial of 33 patients, with a mean (range) follow-up of 6.8 (2-24) months after initiating PC-SPES therapy, serum PSA levels were lower in 87% at 2 months and in 78% at 6 months (n=18, P=0.026). The side-effect s in these patients were nipple tenderness in two (6%) and leg clots requir ing heparinization in two (6%). No gynaecomastia or hot flashes were observ ed in this group and the treatment was well tolerated. Conclusions In this preliminary study, an extract of the phytotherapeutic a gent PC-SPES was active in suppressing the growth of cultured hormone-sensi tive and -insensitive prostate cancer cell lines. In the small clinical stu dy, 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-t erm efficacy of this new phytotherapy.