Serious infection risk and immune recovery after double-unit cord blood transplantation without antithymocyte globulin.

Factors contributing to infection risk after cord blood transplantation (CBT) include the use of anti-thymocyte globulin (ATG), prolonged neutropenia, and failure to transfer immunity. In the present study, we investigated the potential of double-unit CBT without ATG to reduce the risk of infection and evaluated the nature of serious infections in the first year after CBT using this approach. Seventy-two predominantly adult patients underwent CBT for hematologic malignancies; of these, 52 patients received myeloablative conditioning, and 20 received nonmyeloablative conditioning. The peak incidences of bacterial infections (32%), fungal infections (14%), and bacterial/fungal pneumonias (10%) occurred in the first 30 days posttransplantation. Three such infections contributed to early mortality. The peak incidence of viral infections was 31-60 days posttransplantation, affecting 30% of patients. Cytomegalovirus (CMV) was the most common viral infection. CMV infections occurring before day 120 (n = 23) had no relationship with graft-versus-host disease (GVHD), whereas CMV infections occurring after day 120 (n = 5), along with all cases of Epstein-Barr virus viremia (n = 5) and adenoviral enteritis (n = 2), occurred exclusively in the context of GVHD therapy or corticosteroid use for another indication. Viral infections had the highest lethality: 2 were a direct cause of death, and 3 contributed to death. Patients exhibited steady immune recovery, achieving a median CD3(+)4(+) T cell count >200 cells/µL by day 120 post-CBT, and no infection-related deaths occurred after day 120. Our results suggest that double-unit CBT without ATG is associated with prompt T cell recovery, and, unlike in CBT incorporating ATG, infection is rarely a primary cause of death. However, CBT without ATG is associated with a significant risk of GVHD, and serious infections remain a challenge, especially in the setting of GVHD. New strategies are needed to further reduce infectious complications after CBT; these will require earlier neutrophil recovery and more effective prevention of GVHD, ideally without the profound T cell depletion associated with ATG therapy.

Availability of cord blood extends allogeneic hematopoietic stem cell transplant access to racial and ethnic minorities.

Allogeneic transplant access can be severely limited for patients of racial and ethnic minorities without suitable sibling donors. Whether cord blood (CB) transplantation can extend transplant access because of the reduced stringency of required HLA-match is not proven. We prospectively evaluated availability of unrelated donors (URD) and CB according to patient ancestry in 553 patients without suitable sibling donors. URDs had priority if adequate donors were available. Otherwise ≥4/6 HLA-matched CB grafts were chosen utilizing double units to augment graft dose. Patients had highly diverse ancestries including 35% non-Europeans. In 525 patients undergoing combined searches, 10/10 HLA-matched URDs were identified in 53% of those with European ancestry, but only 21% of patients with non-European origins (P < .001). However, the majority of both groups had 5-6/6 CB units. The 269 URD transplant recipients were predominantly European, with non-European patients accounting for only 23%. By contrast, 56% of CB transplant recipients had non-European ancestries (P < .001). Of 26 patients without any suitable stem cell source, 73% had non-European ancestries (P < .001). Their median weight was significantly higher than CB transplant recipients (P <.001), partially accounting for their lack of a CB graft. Availability of CB significantly extends allo-transplant access, especially in non-European patients, and has the greatest potential to provide a suitable stem cell source regardless of race or ethnicity. Minority patients in need of allografts, but without suitable matched sibling donors, should be referred for combined URD and CB searches to optimize transplant access.

Cord blood units with low CD34+ cell viability have a low probability of engraftment after double unit transplantation.

Double unit cord blood (CB) transplantation (CBT) appears to augment engraftment despite only one unit engrafting in most patients. We hypothesized that superior unit quality, as measured by a higher percentage of viable cells postthaw, would determine the engrafting unit. Therefore, we prospectively analyzed 46 double-unit transplants postthaw using flow cytometry with modified gating that included all dead cells. Using a 75% threshold (mean viability minus 2 SD), 20% of units had low CD34+ cell viability, with viability varying according to the bank of origin. Further, in the 44 patients with single unit engraftment, CD34+ cell viability was higher in engrafting units (P=.0016). Although either unit engrafted if both had high CD34+ viability, units with <75% viability were very unlikely to engraft: in 16 patients who received one high and one low CD34+ viability unit, only 1 of 16 units with viability <75% engrafted (P=.0006). Further, in the single patient without engraftment of either unit, both had CD34+ viability <75%. Finally, poor CD34+ viability correlated with lower colony forming units (CFUs) (P=.02). Our data suggests one mechanism by which double unit CBT can improve engraftment is by increasing the probability of transplanting at least one unit with adequate viability and the potential to engraft.

Pre-engraftment syndrome after double-unit cord blood transplantation: a distinct syndrome not associated with acute graft-versus-host disease.

Pre-engraftment syndrome (PES) occurring after cord blood transplantation (CBT) is poorly characterized. We reviewed 52 consecutive double-unit CBT recipients treated for high-risk hematologic malignancies. PES was defined as unexplained fever >38.3 degrees C (101 degrees F) not associated with infection and unresponsive to antimicrobials, and/or unexplained rash occurring before or at neutrophil recovery. CBT recipients (median age, 38 years; range, 3-66 years) received either myeloablative (MA; n=36) or nonmyeloablative (NMA; n=16) conditioning. Sixteen patients (31%) fulfilled PES criteria: 15 with fever (median at onset, 39 degrees C [102.2 degrees F]), 13 of whom also had rash, and 1 with rash alone. The median onset was 9 days (range, 5-12 days) posttransplantation (a median of 14 days before neutrophil recovery). Sixteen patients (14 with PES and 2 with infection and possible PES) received intravenous methylprednisolone (median dose, 1mg/kg; median duration, 3 days); 15 (94%) experienced resolution of fever within 24 hours. Recurrent PES (n=3) resolved with retreatment. There was no association between the development of PES and the likelihood of sustained donor engraftment, speed of neutrophil recovery, grade II-IV acute graft-versus-host disease (aGVHD), day-180 treatment-related mortality (TRM), or survival. PES is common after CBT, precedes neutrophil recovery, is distinct from and does not predict for aGVHD, and responds promptly to short-course corticosteroid therapy.

A "no-wash" albumin-dextran dilution strategy for cord blood unit thaw: high rate of engraftment and a low incidence of serious infusion reactions.

Preparation of cord blood (CB) units for infusion by albumin-dextran dilution without centrifugation may be advantageous for adult patients to minimize cell loss and, unlike a bedside thaw, is still conducted in the controlled laboratory environment. Therefore, we studied CB transplantation (CBT) using this technique in 54 consecutive CBT recipients >20 kg. Patients (median age=42 years [range: 7-66 years]; median weight=71 kg [range: 24-109]) were transplanted for high-risk hematologic malignancies with myeloablative (n=35) or nonmyeloablative (n=19) conditioning and 4-6/6 human leukocyte antigen (HLA)-matched double-unit grafts. One hundred seven units were thawed with dilution, whereas 1 red blood cell (RBC)-replete unit was washed. A 5:1 dextran 40%/25% albumin solution was used. RBC-depleted units (n=104) were diluted >or=5.5-fold (median final volume 200 mL [range: 200-500]), whereas RBC-replete units (n=3) were diluted >or=4-fold (median final volume 400 mL [range: 400-535]). Total nucleated cell (TNC) recovery was 86%; the median infused TNC dose was 2.17x10(7)/kg/unit. Although 35 patients (65%) had a total of 45 infusion reactions (6 nausea, 31 hypertension, 3 pain, 1 rigors/fever, 2 transient hypoxia, 2 renal impairment) requiring additional therapy, there were no infusion-related serious adverse events, and reactions were not related to dimethyl sulfoxide (DMSO) dose/kg. Cumulative incidence of sustained donor engraftment was 94% (95% cumulative incidence [CI]: 87-100) with neutrophil recovery occurring at a median of 25 days (range: 13-43) in myeloablative and 10 days (range: 7-36) in nonmyeloablative recipients. CB thaw with albumin-dextran dilution reduces unit manipulation, and minimizes cell loss, speeds time to infusion, is associated with a tolerable infusion reaction profile, and a high rate of sustained engraftment in CBT recipients >or=20 kg.