Thiotepa and fractionated TBI conditioning prior to allogeneic stem cell transplantation for advanced hematologic malignancies: a phase II single institution trial.

Relapse of hematologic malignancies after allogeneic stem cell transplantation remains a common problem, in particular for patients who have advanced disease at the time of transplantation. Thiotepa has excellent antileukemic and immunosuppressive activity, and could therefore be a useful drug in the conditioning regimen for patients with advanced hematologic neoplasms. We retrospectively analyzed toxicity, engraftment and survival data of 41 patients who received a conditioning regimen of thiotepa (600 mg/m2) and hyperfractionated TBI (10 Gy) prior to matched related (n = 25) or matched unrelated (n = 16) allogeneic stem cell transplantation. The mean age at transplantation was 37.8 years (range 20-59), all but five patients had advanced hematologic malignancies at the time of transplantation. GVHD prophylaxis was with standard cyclosporine and methotrexate. Engraftment was excellent, but the regimen was associated with a high incidence of grade III renal (41%) and hepatic (15%) toxicity, and high transplant-related mortality (44% at day +90). The 3-year event-free survival was 13% and overall survival 14%. We conclude that this regimen requires modification to reduce toxicity.