Claudio G. Brunstein

Acute graft-versus-host disease (aGVHD) is associated with high risk of morbidity and mortality and is a common complication after double umbilical cord blood (UCB) transplantation. To reduce these risks, we established a method of CD4(+)CD25(+)FoxP3(+) T regulatory cell (Treg) enrichment from cryopreserved UCB followed by a 18 (+) 1-day expansion culture including anti-CD3/anti-CD28 antibody-coated beads and recombinant human interleukin-2. In a "first-in-human" clinical trial, we evaluated the safety profile of UCB Treg in 23 patients. Patients received a dose of 0.1-30 × 10(5)UCB Treg/kg after double UCB transplantation. The targeted Treg dose was achieved in 74% of cultures, with all products being suppressive in vitro (median 86% suppression at a 1:4 ratio). No infusional toxicities were observed. After infusion, UCB Treg could be detected for 14 days, with the greatest proportion of circulating CD4(+)CD127(-)FoxP3(+) cells observed on day (+)2. Compared with identically treated 108 historical controls without Treg, there was a reduced incidence of grade II-IV aGVHD (43% vs 61%, P = .05) with no deleterious effect on risks of infection, relapse, or early mortality. These results set the stage for a definitive study of UCB Treg to determine its potency in preventing allogeneic aGVHD. This study is registered at http://www.clinicaltrials.gov as NCT00602693.

The Blood and Marrow Transplant Clinical Trials Network conducted 2 parallel multicenter phase 2 trials for individuals with leukemia or lymphoma and no suitable related donor. Reduced intensity conditioning (RIC) was used with either unrelated double umbilical cord blood (dUCB) or HLA-haploidentical related donor bone marrow (Haplo-marrow) transplantation. For both trials, the transplantation conditioning regimen incorporated cyclophosphamide, fludarabine, and 200 cGy of total body irradiation. The 1-year probabilities of overall and progression-free survival were 54% and 46%, respectively, after dUCB transplantation (n = 50) and 62% and 48%, respectively, after Haplo-marrow transplantation (n = 50). The day +56 cumulative incidence of neutrophil recovery was 94% after dUCB and 96% after Haplo-marrow transplantation. The 100-day cumulative incidence of grade II-IV acute GVHD was 40% after dUCB and 32% after Haplo-marrow transplantation. The 1-year cumulative incidences of nonrelapse mortality and relapse after dUCB transplantation were 24% and 31%, respectively, with corresponding results of 7% and 45%, respectively, after Haplo-marrow transplantation. These multicenter studies confirm the utility of dUCB and Haplo-marrow as alternative donor sources and set the stage for a multicenter randomized clinical trial to assess the relative efficacy of these 2 strategies. The trials are registered at www.clinicaltrials.gov under NCT00864227 (BMT CTN 0604) and NCT00849147 (BMT CTN 0603).

We evaluated the efficacy of umbilical cord blood (UCB) in the setting of a nonmyeloablative regimen consisting of fludarabine (200 mg/m2), cyclophosphamide (50 mg/kg), and a single fraction of total body irradiation (200 cGy) with cyclosporine and mycophenolate mofetil for posttransplantation immunoprophylaxis. The target cell dose for the UCB graft was 3.0 x 10(7) nucleated cells/kg, resulting in the selection of a second partially human leukocyte antigen-matched UCB unit in 85%. One hundred ten patients with hematologic disease were enrolled. Neutrophil recovery was achieved in 92% at a median of 12 days. Incidences of grades III and IV acute and chronic graft-versus-host disease (GVHD) were 22% and 23%, respectively. Transplantation-related mortality was 26% at 3 years. Survival and event-free survival (EFS) at 3 years were 45% and 38%, respectively. Favorable risk factors for survival were absence of high-risk clinical features (Karnofsky 50-60, serious organ dysfunction, recent fungal infection, P < .01) and absence of severe GVHD (P = .04), and favorable risk factors for EFS were absence of high-risk clinical features (P < .01) and use of 2 UCB units (P = .07). These findings support the use of UCB after a nonmyeloablative conditioning as a strategy for extending the availability of transplantation therapy, particularly for older patients.

The success of allogeneic hematopoietic cell transplantation (HCT) is typically assessed as individual complications, including graft-versus-host disease (GVHD), relapse, or death, yet no one factor can completely characterize cure without ongoing morbidity. We examined a novel composite end point of GVHD-free/relapse-free survival (GRFS) in which events include grade 3-4 acute GVHD, systemic therapy-requiring chronic GVHD, relapse, or death in the first post-HCT year. In 907 consecutive University of Minnesota allogeneic HCT recipients (2000-2012), 1-year GRFS was 31% (95% confidence interval [CI] 28-34). Regression analyses showed age, disease risk, and donor type significantly influencing GRFS. Adults age 21+ had 2-fold worse GRFS vs children; GRFS did not differ beyond age 21. Adjusted for conditioning intensity, stem cell source, disease risk, age, and transplant year, HLA-matched sibling donor marrow resulted in the best GRFS (51%, 95% CI 46-66), whereas HLA-matched sibling donor peripheral blood stem cells were significantly worse (25%, 95% CI 20-30, P = .01). GRFS after umbilical cord blood transplants and marrow from matched unrelated donors were similar (31%, 95% CI 27-35 and 32%, 95% CI 22-42, respectively). Because GRFS measures freedom from ongoing morbidity and represents ideal HCT recovery, GRFS has value as a novel end point for benchmarking new therapies.

Effectiveness of double umbilical cord blood (dUCB) grafts relative to conventional marrow and mobilized peripheral blood from related and unrelated donors has yet to be established. We studied 536 patients at the Fred Hutchinson Cancer Research Center and University of Minnesota with malignant disease who underwent transplantation with an human leukocyte antigen (HLA)-matched related donor (MRD, n = 204), HLA allele-matched unrelated donor (MUD, n = 152) or 1-antigen-mismatched unrelated adult donor (MMUD, n = 52) or 4-6/6 HLA matched dUCB (n = 128) graft after myeloablative conditioning. Leukemia-free survival at 5 years was similar for each donor type (dUCB 51% [95% confidence interval (CI), 41%-59%]; MRD 33% [95% CI, 26%-41%]; MUD 48% [40%-56%]; MMUD 38% [95% CI, 25%-51%]). The risk of relapse was lower in recipients of dUCB (15%, 95% CI, 9%-22%) compared with MRD (43%, 95% CI, 35%-52%), MUD (37%, 95% CI, 29%-46%) and MMUD (35%, 95% CI, 21%-48%), yet nonrelapse mortality was higher for dUCB (34%, 95% CI, 25%-42%), MRD (24% (95% CI, 17%-39%), and MUD (14%, 95% CI, 9%-20%). We conclude that leukemia-free survival after dUCB transplantation is comparable with that observed after MRD and MUD transplantation. For patients without an available HLA matched donor, the use of 2 partially HLA-matched UCB units is a suitable alternative.