Optimal therapy of biochemically relapsed prostate cancer (BRPC) after local treatment is elusive. An established modified citrus pectin (PectaSol®, P-MCP), a dietary polysaccharide, is an established antagonist of galectin-3, a carbohydrate-binding protein involved in cancer pathogenesis. Based on PSA dynamics, we report on the safety and the primary outcome analysis of a prospective phase II study of P-MCP in non-metastatic BRPC based. Sixty patients were enrolled, and one patient withdrew after a month. Patients (n = 59) were given P-MCP, 4.8 grams X 3/day, for six months. The primary endpoint was the rate without PSA progression and improved PSA doubling time (PSADT). Secondary endpoints were the rate without radiologic progression and toxicity. Patients that did not progress by PSA and radiologically at six months continued for an additional twelve months. After six months, 78% (n = 46) responded to therapy, with a decreased/stable PSA in 58% (n = 34), or improvement of PSADT in 75% (n = 44), and with negative scans, and entered the second twelve months treatment phase. Median PSADT improved significantly (p = 0.003). Disease progression during the first 6 months was noted in only 22% (n = 13), with PSA progression in 17% (n = 10), and PSA and radiologic progression in 5% (n = 3). No patients developed grade 3 or 4 toxicity.
Keywords: PSA doubling time; PectaSol; modified citrus pectin; non-metastatic biochemically relapsed prostate cancer.