Phase I study of SOAz

SOAz, an inorganic cyclic derivative, was given as a single iv injection through one cycle in a phase I trial. Dose-limiting toxic effects noted were neutropenia and thrombocytopenia occurring at doses greater than or equal to 220 mg/M2 in patients with prior myelosuppressive treatment. The time to nadir for blood cell counts was long, as well as the time to recovery, so cumulative toxicity could be suspected. No other significant toxicity was noted. In patients with measurable volume, no significant antitumor responses were seen. For further study, the dose of 220 mg/m2 every 6-8 weeks according to hematologic restoration is recommended.