 - Patients who cannot receive any asparaginase products E. Coli, PEG-asparaginase, or Erwinia asparaginase on this study eg, due to prior severe pancreatitis, stroke or other toxicity are not eligible; patients who initially receive asparaginase, but must discontinue due to toxicity, remain eligible; patients with clinically significant prior allergies to pegaspargase are eligible if Erwinia L-asparaginase can be substituted 