This study investigates the use of an investigational medication in combination with irinotecan for treating children with solid tumors that have returned or not responded to standard treatments. Solid tumors are abnormal masses of tissue that usually do not contain cysts or liquid areas. The purpose of this study is to find the best dose of the investigational medication and to understand the side effects when used with irinotecan.
Participants in the study will receive the investigational medication and irinotecan on a specific schedule. The investigational medication is given on days 1 through 5 of a 21-day cycle. The study will also look at how the investigational medication moves through the body, known as pharmacokinetics, and any side effects that occur during the treatment.
- Who can participate: Children with solid tumors that have either returned or not responded to standard therapy can participate. They must have had a confirmed diagnosis of cancer, except for certain brain tumors and conditions with specific tumor markers. Additionally, participants must have a disease state for which there is no known curative therapy or therapy proven to prolong survival with an acceptable quality of life.
- Study details: Participants will take the investigational medication and irinotecan on days 1 through 5 of a 21-day cycle. A placebo is not used in this study.

