Comparison of doxorubicin with cycloleucine in the treatment of sarcomas

In this patient series, doxorubicin and cycloleucine at a dose of 300 mg/kg both show response rates in the treatment of advanced soft tissue sarcomas of about 15%. Lower doses of cycloleucine (200 mg/kg) yielded less toxicity but were less effective against the sarcomas (6% response rate, three of 51 patients). There were no complete responses with cycloleucine and there were three with doxorubicin. Survival times for patients receiving doxorubicin were significantly longer than those of patients receiving cycloleucine at doses of 300 mg/kg (P less than 0.001) or 200 mg/kg (P = 0.02). The estimated survival times were 29 weeks for doxorubicin and 21 (300 mg/kg) and 18 (200 mg/kg) weeks for cycloleucine. Toxic effects due to cycloleucine were excessive, with severe thrombocytopenia and central nervous system depression being the most prominent.