late changes were not seen in serial knee radiographs obtained in seven patients whose growth plate was open at study enrollment. Mild diarrhea occurred in 60 cycles, and was well controlled with loperamide. Complete response was achieved in a patient with Wilms tumor after 8 cycles. In another patient with relapsed Wilms tumor, a lung nodule persisted despite a dramatic response initially. This nodule was resected after 8 cycles, and did not have histological evidence of viable tumor. 1393124-08-7 Therefore, this patient was determined to have a complete response. Partial responses were seen in patients with Wilms tumor, medulloblastoma and hepatocellular carcinoma. The patient with medulloblastoma was removed from protocol therapy by the primary oncologist after 4 Zosuquidar trihydrochloride citations cycles to administer radiation therapy. One patient was removed from protocol therapy after cycle 1 due to progressive disease. Another patient with an angiosarcoma of the heart and a chest wall mass showed a dramatic response to the first two cycles with greater than 50 reduction in tumor size on imaging. The start of his third cycle was delayed due to fever by one week. He developed progressive disease during this period and was removed from protocol therapy. Five patients completed all 12 cycles of chemotherapy. Irinotecan has been administered using various schedules in both adults and children. Preclinical studies in pediatric tumors by Houghton et al, showed that a protracted schedule of irinotecan given daily for 5 days per week for 2 consecutive weeks resulted in greater response rates when compared to the same dose administered over 5 days. Based on this, irinotecan was initially administered on a protracted schedule of 5 consecutive days for 2 weeks in pediatric studies. A subsequent randomized phase II study of protracted versus 5 day schedule of irinotecan did not show any difference in response rates in rhabdomyosarcoma patients. Another trial comparing the two regimens of oral irinotecan given with vincristine and temozolomide reported higher frequency of dose limiting toxicity in the protracted regimen. Since the 5 day schedule is more convenient for patients, we used this schedule in our trial. The MTD for irinotecan administered as a single agen
