Oral idarubicin in the treatment of advanced breast cancer

Idarubicin (IDA), a more lipophilic derivative of daunorubicin, has shown activity after oral administration. In November 1983 we initiated a phase II study administering IDA, 45 mg/m2, in a 3 weekly schedule as first line chemotherapy to postmenopausal women with advanced breast cancer. Among 50 eligible patients a response rate of 36% (95% confidence interval (CI): 23-51) was obtained. Median time to treatment failure was 22 weeks (95% CI: 15-32). In November 1986, a sequential phase II study with IDA given in a weekly schedule was initiated. Patient characteristics was comparable to the first study. Among 53 evaluable patients, the response rate was 34% (95% CI: 22-48), and median time to treatment failure was 19 weeks (95% CI: 13-33). Therapeutic efficacy in the two studies was comparable and similar to published data on doxorubicin. Hematologic toxicity was equal while non-hematologic toxicity was considerably lower in the weekly schedule. A phase III comparison of IDA to doxorubicin or epi-doxorubicin is warranted, in order to clarify the role of IDA in the treatment of advanced breast cancer.