Beginning 82 days after BMT/PBSCT, patients receive alternating courses of oral VP-16 and MOAB 3F8 for a total of 8 courses (total of 4 courses of each drug). Patients receive oral VP-16 3 times daily on days 1-21, with courses repeating every 28 days. Patients receive MOAB 3F8 IV within 90 minutes on days 1-5, with courses repeating every 35 days.