The combination of irinotecan and temozolomide showed activity in the treatment of several solid organ tumors, brain tumors and neuroblastoma. In one study rNB patients received a median of 5 courses of 5 days irinotecan and temozolomide every 3 to 4 weeks with a cumulative dose of 35% lower than in the RIST design. 33% had disease regression with 8% CR or PR. A phase II study in rNB also using irinotecan and temozolomide with a substantially lower intensity showed a response rate of 15%.