[Phase I study of 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077). Phase I Study Group]

A phase I study on TA-077, a water-soluble nitrosourea, was performed by a 9-institution clinical group using 89 patients with various malignant tumors. The study consisted of single-dose i.v. administration and daily i.v. administration for 3-6 consecutive days. The dose-limiting factor was delayed leukopenia and thrombocytopenia which reached nadirs about 5 weeks and about 4 weeks after the initiation of administration and recovered in 2 to 3 weeks, respectively. Gastrointestinal toxicity, such as nausea, vomiting and anorexia, appeared in the early stage of treatment, although most of these symptoms were mild or moderate. Other side effects, including transient liver and renal dysfunctions observed in a few cases, were mild and appeared not to be dose-dependent. M.T.D. in single administration was considered to be more than 3,000 mg/m2 and M.T.D. in 5-day consecutive administration was considered to be 1,000 mg/m2/day. The recommended dose schedule for initiation of the phase II study was assumed to be 700 to 900 mg/m2/day for 5 consecutive days.