Adult Umbilical Cord Blood Transplantation Using Myeloablative Thiotepa, Total Body Irradiation, and Fludarabine Conditioning.

Treatment-related mortality (TRM) remains elevated in adult patients undergoing umbilical cord blood transplantation (UCBT), including an early rise in TRM suggestive of excessive toxicity associated with the standard myeloablative total body irradiation (TBI), fludarabine, and cyclophosphamide regimen. In an attempt to reduce regimen-related toxicity, we previously studied a modified myeloablative regimen with TBI (1350 cGy) and fludarabine (160 mg/m2); TRM was decreased, but neutrophil engraftment was suboptimal. Therefore, to improve engraftment while still minimizing regimen-related toxicity, we piloted a myeloablative regimen with the addition of thiotepa (10 mg/kg) to TBI and fludarabine conditioning. Thirty-one adult patients (median age, 46 years; range, 19 to 65) with hematologic malignancies (acute leukemia/myelodysplastic syndrome, 77%; lymphoid malignancy, 23%) underwent single (n = 1) or double (n = 30) UCBT from 2010 to 2015 at our institution. The cumulative incidence of neutrophil engraftment was 90% (95% confidence interval [CI], 70% to 97%) by 60 days, with a median time to engraftment of 21 days (95% CI, 19 to 26). The cumulative incidence of platelet engraftment was 77% (95% CI, 57% to 89%) by 100 days, with a median time to engraftment of 47 days (95% CI, 37 to 73). Cumulative incidences of grades II to IV and grades III to IV acute graft-versus-host disease (GVHD) at day 100 were 45% (95% CI, 27% to 62%) and 10% (95% CI, 2% to 23%), respectively. The overall incidence of chronic GVHD at 2 years was 40% (95% CI, 22% to 57%), with 17% of patients (95% CI, 6% to 33%) experiencing moderate to severe chronic GVHD by 2 years. TRM at 180 days was 13% (95% CI, 4% to 27%), at 1 year 24% (95% CI, 10% to 41%), and at 3 years 30% (95% CI, 13% to 49%). Relapse at 1 year was 13% (95% CI, 4% to 27%) and at 3 years 19% (95% CI, 6% to 38%). With a median follow-up of 35.5 months (95% CI, 12.7 to 52.2), disease-free and overall survival at 3 years were 51% (95% CI, 29% to 69%) and 57% (95% CI, 36% to 73%), respectively. This regimen represents a reasonable alternative to myeloablative conditioning with TBI, fludarabine, and cyclophosphamide and warrants further study.