- Chemotherapy arm: a. Determine progression free survival for younger children without NF1 treated with chemotherapy and randomized to either the 2-drug or the 3-drug induction regimen. b. Determine the distribution of response at week 24 (after induction) for younger children without NF1 treated with chemotherapy and randomized to either the 2-drug or the 3-drug induction regimen. c. Determine progression free survival for children with NF1treated with chemotherapy.