- Treosulfan ≥ 42g/m2 total dose IV *Regimens may include secondary agents such as, but not limited to Ara-C, Fludarabine, VP-16. Regimens that combine Busulfan and TBI or treosulfan and TBI are allowed as long as the Busulfan or treosulfan meets or exceeds the dose listed and the TBI is below the dose listed.