 To evaluate the activity of Erwinaze to reduce the serum glutamine to the desired level, the dose will be adjusted according to a pre-defined algorithm based on 48-hour trough serum glutamine level biochemical response prior to dose 6 of each patient. If the safety profile is acceptable, we will enroll up to a total of 15 patients at that dose level to better study and analyze the glutamine-reducing effect of Erwinaze at the defined dose. 