Metronomic Chemotherapy in Wilms Tumor (MetroWilms-1906)

This study is testing metronomic chemotherapy — a strategy of giving lower doses of chemotherapy continuously rather than in large, spaced-out cycles — in children with Wilms tumor (a kidney cancer most common in children) whose cancer has returned or stopped responding to standard treatment. **You may be eligible if...** - You are between 18 months and 17 years old - You have been diagnosed with Wilms tumor that has relapsed (come back) or is not responding to treatment - Your Wilms tumor was confirmed by tissue biopsy at the time of original diagnosis - You have already received at least 2 prior rounds of chemotherapy **You may NOT be eligible if...** - You have a history of a different cancer in the past 5 years - You received chemotherapy or radiation to the target lesion within the past 3 weeks - You are pregnant or breastfeeding - You have serious organ damage that would make chemotherapy unsafe Talk to your doctor to see if this trial is right for you.