Phase I trial of pentosan polysulfate.

Pentosan polysulfate is a semisynthetic pentasaccharide heparinoid derived from beechwood shavings. A total of nineteen patients with various adult solid tumors were treated with three dose levels (15, 22.5, and 30 mg/m2/dose) of subcutaneous pentosan polysulfate every 6 hours. The dose limiting toxicities were thrombocytopenia and elevated transaminases at the dose of 30 mg/m2 every 6 hours. The recommended starting dose for phase II trials is 22.5 mg/m2 given every 6 hours. There was an increase in anticoagulant activity as measured by activated partial thromboplastin time (aPTT) at the dose of 22.5 mg/m2 every 6 hours in most patients. There were no objective responses and three patients had stable disease lasting 16, 19 and 76 weeks.