Phase I trial of PC-Spes2 in advanced hormone refractory prostate cancer

There are few treatment options for prostate cancer once it becomes hormone refractory, with a mean life expectancy of 9-12 months. During the period 1997-2002, a product known as PC-Spes, containing a mixture of extracts from eight herbs based on the principles of traditional Chinese medicine, was reported to inhibit prostate cancer cell growth in vitro and reduce PSA in patients with hormone refractory prostate cancer (HRPC). This product was withdrawn from the market in 2002 due to concerns over quality control and reported contamination with traces of warfarin, indomethacin and diethylstilbesterol. PC-spes2, manufactured by Active Botanicals Ltd. (UK) with strict, independently-conducted quality control, has demonstrated no contaminants by high pressure liquid chromatography and liquid chromatography/mass spectroscopy. This compound was investigated in a single-centre, prospective, open pilot study. Eighteen patients with HRPC, mean age 72, median Gleason sum 8 (range 4-9) and median PSA 110 (range 4-2870) with three consecutive monthly increases in PSA were studied. Ten patients withdrew during the study period with significant diarrhoea (8 out of the first 10 patients at one month and only 2 out of the last 8 due to an improved dosing schedule). At one month, 7 out of 10 patients had a drop in their PSA doubling time or PSA velocity, which was still apparent in 4 out of 5 patients still on trial at three months and all three patients still on trial at six months. No serious adverse events or derangement of coagulation were observed. PC-Spes2 offers renewed hope and a safe alternative treatment option for patients with advanced HRPC. Further investigation with phase II trials is warranted.