BACKGROUNDGambogic acid is a pure active compound isolated from the traditional Chinese medicinal plant gamboge (Garcinia morella Desv.). Based on the preliminary results of a phase I study, this phase IIa study compared the efficacy and safety of different dosage schedules of gambogic acid in patients with advanced malignant tumors.

METHODSPatients with advanced or metastases cancer who had not received any effective routine conventional treatment or who had failed to respond to the existing conventional treatment were randomly assigned to receive either 45 mg/m(2) gambogic acid intravenously from Days 1 to 5 of a 2-week cycle (Group A), or 45 mg/m(2) every other day for a total of five times during a 2-week cycle (Group B). The primary endpoint was objective response rate (ORR).

RESULTSTwenty-one patients assigned to Group A and 26 to Group B were included in the final analysis. The ORRs were 14.3% in Group A and 0% in Group B. It was not possible to analyze the significant difference because one of the values was zero. The disease control rates (DCRs) were 76.2% in Group A and 61.5% in Group B (P = 0.0456). The observed adverse reactions were mostly Grades I and II, and occurred in most patients after administration of the trial drug. There was no significant difference in the incidence of adverse reactions between the two arms.

CONCLUSIONSThe preliminary results of this phase IIa exploratory study suggest that gambogic acid has a favorable safety profile when administered at 45 mg/m(2). The DCR was greater in patients receiving gambogic acid on Days 1 - 5 of a 2-week cycle, but the incidence of adverse reactions was similar irrespective of the administration schedule.