Phase I-II study on weekly administration of pirarubicin in patients with metastatic breast cancer

A phase I-II study of weekly low-dose pirarubicin was performed in 19 patients with advanced breast cancer. The goal was to establish the optimal dose intensity, i.e., the maximal dose applicable at tolerable toxicity within the intended schedule. Each of the four different dose groups used (20, 24, 25, and 27 mg/m2) comprised 4-5 patients. In over 47% of patients, objective remissions were obtained (confidence interval 26%; 71%) including one complete and eight partial remissions; the median duration of remission was 41 weeks (range 16-72), and the median time to reach remission was 12 weeks (range 6-36). Efficacy of treatment was more dependent on prior chemotherapy than on pirarubicin dosage. The weekly i.v. push injection of the drug was easily applicable at an outpatient clinic and well tolerated. WHO grade 3 was the highest toxicity observed for leukopenia (3/19), leukopenia associated with infection (1/19), nausea/vomiting (2/19) and alopecia (6/19). More severe myelosuppression was avoided by interrupting the weekly application until recovery of leukocytes to greater than or equal to 3.5 x 10(3)/mm3. No clinical signs of cardiotoxicity were observed. Generally, mild to moderate signs of cardiac dysfunction acquired during therapy were detected by special cardiac monitoring. Only in 3 of 19 patients was a cumulative dose of more than 550 mg/m2 surpassed. This was accepted as the upper limit for conventional anthracycline therapy. The median cumulative dose applied was 325 mg/m2/week (range 58.2-800.0). Because of maldistribution of prognostic factors, no dose-response relationship could be established. With respect to the total time for which each patient was studied, the dose group of 27 mg/m2 achieved the highest dose intensity with a median of 17.4 mg/m2/week (range 13.5-22.4). Therefore, the dosage of 27 mg/m2/week is recommended to be used in further phase II-III trials of weekly applied pirarubicin.