Phase I dose-escalating study of ES-285 given as a three-hour intravenous infusion every three weeks in patients with advanced malignant solid tumors
Background ES-285 (spisulosine) is a novel compound derived from the marine mollusk Spisula polynoma with evidence of preclinical antitumor activity. This phase I clinical trial was designed to identify the maximum tolerated dose (MTD) and the recommended dose for phase II trials (RD), as well as to evaluate the safety profile, pharmacokinetics and preliminary efficacy data of ES-285 in patients with advanced solid tumors. Patients and Methods Sixty-one patients at two medical institutions were treated with a 3-h ES-285 intravenous infusion every 3 weeks. Nine dose levels were evaluated. Results No dose-limiting toxicities (DLTs) were observed during dose escalation from 4 to 128 mg/m2. Six patients had seven DLTs at the three highest dose levels tested: 256 mg/m2 (n = 2), 200 mg/m2 (n = 3) and 160 mg/m2 (n = 1). Grade 3/4 transaminase increases (n = 3), grade 3/4 central nervous system disorders [confusion (n = 2) and ataxia (n = 1)], and grade 3 pyrexia (n = 1) were the dose-limiting toxicities found with this ES-285 administration schedule. Pharmacokinetic analysis showed ES-285 dose linearity, wide distribution and a long half-life. One non-confirmed partial response was observed in a patient with metastatic melanoma treated with ES-285 128 mg/m2, and 18 patients showed stable disease at different dose levels, lasting longer than 3 months in six patients. Conclusion Dose level VIII (200 mg/m2) was considered the MTD, and dose level IX (160 mg/m2) was defined as the RD. Limited antitumor activity was observed.