 The second Part: Patients receive 6 cycles of ifosfamide 1.2gm2 iv on days 3-5; pegaspargase 2000Um2 im on day 1; gemcitabine 800mgm2 iv on days 3,8; cisplatin 25 mgm2 iv on days 3-5; dexamethasone 20mgm2 iv on days 3-6. IPGDP regimen is repeated every 3 weeks. If the disease is considered to progress or as stable after 2 cycles or 4 cycles of chemotherapy, the patient will withdraw from this study. 