Pentostatin-based regimens have been studied as a conditioning strategy for patients undergoing allogeneic stem cell transplantation. Chan et al. evaluated 18 myelodysplastic syndrome (MDS) patients ineligible for standard allogeneic transplantation. In that series, patients received conditioning with a preparative regimen of photopheresis day -7 and -6, pentostatin 4 mg/m^2 by continuous infusion day -5 and -4, and total body irradiation 600 centigray (cGy) in 3 fractions day -3 and -2, followed by allogeneic stem cell infusion from 6/6 or 5/6 HLA-matched related donors or 6/6 HLA-matched unrelated donors. Sixteen of 18 (89%) patients developed full donor chimerism, with no day +100 transplant-related mortality (TRM). Grade 2 to 4 aGVHD and extensive chronic graft versus host disease (GVHD) developed in 19% and 18% of patients, respectively. Disease relapse occurred in 2 patients. At a median follow-up of 14 months (range, 1-35 months), the 1-year failure-free and overall survival were 64% and 65%, respectively. These findings clearly suggest that Pentostatin-based regimens are capable of achieving a successful donor engraftment and durable disease-remission with significantly lesser transplant toxicity and grade 2 to 4 acute GVHD. Pavletic et al., demonstrated that Pentostatin induces significant lympho-depleting effects with a promising safety, supporting its use as a conditioning regimen in non-myeloablative strategies with hematopoietic cell infusions as early as 7 days after initiation of Pentostatin.