Thiotepa/cyclophosphamide/TBI as a conditioning regimen for allogeneic hematopoietic stem cell transplantation in patients aged 50 years and over.

Objective: To reduce the relapse rate for hematological malignancies after allogeneic hematopoietic stem cell transplantation, we employed a myeloablative regimen comprising thiotepa 400 mg/m(2), cyclophosphamide 3,600 mg/m(2) and total body irradiation 10 Gy.

Materials And Methods: Subjects comprised 17 patients (median age, 53 years; range, 50-56 years) with hematological malignancies who received allogeneic hematopoietic stem cell transplantation from HLA-identical related (n=6), HLA-mismatched family (n=2) or unrelated donors (n=9). Prophylaxis of acute graft-versus-host disease (GVHD) consisted of short-term methotrexate and cyclosporine (n=4) or short-term methotrexate and tacrolimus (n=13).

Results: No grade IV regimen-related toxicities as determined by Bearman's criteria were encountered. Acute grade II-IV GVHD developed in 7 patients, with chronic GVHD in 11 patients. With a median follow-up of 39 months, 3 years survival rate after transplantation was 59%. Two patients died due to infection by 100 days after transplantation. Only 1 patient with Philadelphia-positive acute lymphoblastic leukemia experienced relapse. Eight patients died of non-leukemic causes (sepsis, n=2; liver dysfunction, n=2; idiopathic interstitial pneumonia, n=1; bacterial pneumonia, n=1; bronchiolitis obliterans resulting from chronic GVHD, n=1; and disseminated infection with varicella zoster virus, n=1).

Conclusions: This regimen was tolerable, but a large trial is warranted to confirm the efficacy of this conditioning.