- Part B: Patients receive bortezomib IV over 3-5 seconds at the MTD on days 1 and 8, dexamethasone IV on days 1-3 and 8, etoposide IV over 2 hours on days 1-3, and ifosfamide IV continuously over 24-hours and carboplatin IV over 2 hours on day 2. Treatment repeats every 21 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. Some patients may undergo hematopoietic stem cell transplantation (HSCT).