[Early phase II study of TAT-59 in patients with advanced or recurrent breast cancer--a multicenter dose finding...

A dose finding early phase II study of TAT-59, a new triphenylethylene derivative, was performed in patients with advanced or recurrent breast cancer. TAT-59 was given orally for over 8 weeks at a daily dose of 10 mg, 20 mg or 40 mg/day. Thirty-six, 38 and 35 patients were eligible in the group treated with 10, 20 and 40 mg of TAT-59, respectively. The proportion of patients obtaining a complete or partial response with 10 mg/day, 20 mg/day and 40 mg/day of TAT-59 was 28.6% (10/35), 28.6% (10/35) and 25.8% (8/31) in the evaluable cases, respectively. The median duration of initial response with TAT-59 was 38.5 days, 26.5 days and 25.6 days, respectively. The frequent adverse reactions observed in all dosing groups included hot flashes, anorexia, nausea and vomiting, sweating, and abnormal values in liver function tests. In these adverse reactions, the incidence of hot flashes, which might be caused by the pharmacologic function of TAT-59 was 0.0% (0 of 35), 2.9% (1 of 35) and 10.0% (3 of 30) in the evaluable cases receiving 10 mg, 20 mg and 40 mg of TAT-59, respectively. In conclusion, it was recommended that the optimal dose in terms of efficacy and adverse reactions should be 20 mg/day.