Cat's claw (Uncaria tomentosa) is a native amazonic plant that exhibits anti-inflammatory and antitumor properties. Patients and methods: This prospective phase II study will assess the effects of a 100-mg dose of a dry extract of U. tomentosa three times per day on individuals with advanced solid tumors, with no further therapeutic options and with at least 2 months life expectancy. In addition, several biochemical and inflammatory parameters will be analyzed.