The syndrome of microangiopathic hemolysis associated with renal failure, neurologic impairment, or both is a recognized complication of hematopoietic stem cell transplantation. This entity is often called hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP), yet it is clear that the pathophysiology of transplant-associated HUS/TTP is different from that of classic HUS or TTP. Furthermore, the incidence of this syndrome varies from 0.5% to 76% in different transplant series, primarily because of the lack of a uniform definition. The toxicity committee of the Blood and Marrow Transplant Clinical Trials Network has reviewed the current literature on transplant-related HUS/TTP and recommends that it be henceforth renamed posttransplantation thrombotic microangiopathy (TMA). An operational definition for TMA based on the presence of microangiopathic hemolysis and renal and/or neurologic dysfunction is proposed. The primary intervention after diagnosis of TMA should be withdrawal of calcineurin inhibitors. Plasma exchange, although frequently used in this condition, has not been proven to be effective. In the absence of definitive trials, plasma exchange cannot be considered a standard of care for TMA. It is hoped that these positions will improve the identification and reporting of this devastating complication after hematopoietic stem cell transplantation and facilitate future clinical studies for its prevention and treatment.

Outcomes of 159 young patients with inherited metabolic disorders (IMDs) undergoing transplantation with partially HLA-mismatched unrelated donor umbilical cord blood were studied to investigate the impact of graft and patient characteristics on engraftment, overall survival (OS), and graft-versus-host disease (GVHD). Patients received myeloablative chemotherapy (busulfan, cyclophosphamide, ATG) and cyclosporine-based GVHD prophylaxis. Infused cell doses were high (7.57 ؋ 10 7 /kg) because of the patients' young age (median, 1.5 years) and small size (median, 12 kg). Median follow-up was 4.2 years (range , 1-11 years)

BACKGROUND Umbilical-cord blood has been used as the source of hematopoietic stem cells in an estimated 30,000 transplants. The limited number of hematopoietic cells in a single cord-blood unit prevents its use in recipients with larger body mass and results in delayed hematopoietic recovery and higher mortality. Therefore, we hypothesized that the greater numbers of hematopoietic cells in two units of cord blood would be associated with improved outcomes after transplantation. METHODS Between December 1, 2006, and February 24, 2012, a total of 224 patients 1 to 21 years of age with hematologic cancer were randomly assigned to undergo double-unit (111 patients) or single-unit (113 patients) cord-blood transplantation after a uniform myeloablative conditioning regimen and immunoprophylaxis for graft-versus-host disease (GVHD). The primary end point was 1-year overall survival. RESULTS Treatment groups were matched for age, sex, self-reported race (white vs. nonwhite), performance status, degree of donor–recipient HLA matching, and disease type and status at transplantation. The 1-year overall survival rate was 65% (95% confidence interval [CI], 56 to 74) and 73% (95% CI, 63 to 80) among recipients of double and single cord-blood units, respectively (P = 0.17). Similar outcomes in the two groups were also observed with respect to the rates of disease-free survival, neutrophil recovery, transplantation-related death, relapse, infections, immunologic reconstitution, and grade II–IV acute GVHD. However, improved platelet recovery and lower incidences of grade III and IV acute and extensive chronic GVHD were observed among recipients of a single cord-blood unit. CONCLUSIONS We found that among children and adolescents with hematologic cancer, survival rates were similar after single-unit and double-unit cord-blood transplantation; however, a single-unit cord-blood transplant was associated with better platelet recovery and a lower risk of GVHD.

Graft failure occurs in approximately 20% of patients after unrelated umbilical cord blood transplantation (UCBT). This could be because of inadequate potency of the cord blood unit (CBU). To this end, we investigated the impact of graft characteristics on engraftment and survival of 435 primarily pediatric (median age: 5.3 years) patients receiving a single-unit unrelated UCBT after myeloablative conditioning from 2000 to 2008. Pre-cryopreservation (pre-cryo) graft characteristics were provided by the banks. Post-thaw parameters were measured on dextran/albumin-washed grafts. Post-thaw recovery of the colony-forming unit (CFU), a biological assay reflecting functional viability of the cord blood cells was the lowest percent age (median 21.2%, mean 36.5%) of the pre-cryo value, regardless of the bank of origin. The cumulative incidences of neutrophil and platelet engraftment were 76.9% (95%, confidence interval [CI], 71.3%-82.5%) and 55% (95% CI, 49.3%-60.7%), respectively. Univariate and separate multivariate models using pre-cryo and post-thaw datasets including clinical parameters identified predictors of engraftment and survival. In multivariate modeling, higher CFU dosing was the only pre-cryo graft characteristic predictive of neutrophil (P = .0024) and platelet engraftment (P = .0063). In the post-thaw model, CFU dose best predicted neutrophil and platelet engraftment (both P < .0001). Comparatively, CD34(+) and total nucleated cell (TNC) were only weakly predictive in post-thaw neutrophil and platelet engraftment models, respectively. In conclusion, CFU dose is a strong independent predictor of engraftment after unrelated UCBT and should be used to assess potency when selecting CBUs for transplantation.

The Sickle Cell Unrelated donor Transplant trial (SCURT trial) of the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) is a phase II study of the toxicity and efficacy of unrelated donor hematopoietic cell transplantation in children with severe sickle cell disease (SCD) using a reduced intensity conditioning regimen. Here we report the results for the cord blood cohort of this trial. Eight children with severe SCD underwent unrelated donor cord blood transplantation (CBT) following alemtuzumab, fludarabine and melphalan. Cyclosporine or tacrolimus and mycophenolate mofetil were administered for graft-versus-host disease (GVHD) prophylaxis. Donor/recipient HLA match status was 6/6 (n=1) or 5/6 (n=7), based on low/intermediate resolution molecular typing at HLA -A, -B, and high resolution typing at -DRB1. Median recipient age was 13.7 years (range 7.4 to 16.2 years), and median weight was 35.0 kg (range 25.2 to 90.2 kg). The median pre-cryopreservation total nucleated cell dose was 6.4 × 107 /kg (range 3.1 to 7.6) and the median post-thaw infused CD34 cell dose was 1.5 × 105 /kg (range 0.2 to 2.3). All patients achieved neutrophil recovery (ANC>500/mm3) by day 33 (median 22 days). Three patients who engrafted had 100% donor cells by day 100, which was sustained and five patients had autologous hematopoietic recovery. Six of eight patients had a platelet recovery to > 50,000/mm3 by day 100. Two patients developed grade II acute GVHD. Of these, one developed extensive chronic GVHD and died of respiratory failure 14 months post-transplant. With a median follow up of 1.8 years (range 1 – 2.6), 7 patients are alive with a 1-year survival of 100% and 3 of 8 are alive without graft failure or disease recurrence. Conclusion Based upon the high incidence of graft rejection after unrelated donor CBT, enrollment onto the cord blood arm of the SCURT trial was suspended. However, since this reduced intensity regimen has demonstrated a favorable safety profile, this trial remains open to enrollment for unrelated marrow donor transplants. Novel approaches aimed at improving engraftment will be needed before unrelated CBT can be widely adopted for transplanting patients with severe SCD.

Acute graft-versus-host disease (aGVHD)is the primary limitation of allogeneic hematopoietic cell transplantation. Corticosteroids remain the standard initial therapy, yet only 25% to 41% of patients completely respond. This randomized, 4-arm, phase 2 trial was designed to identify the most promising agent(s) for initial therapy for aGVHD. Patients were randomized to receive methylprednisolone 2 mg/ kg per day plus etanercept, mycophenolate mofetil (MMF), denileukin diftitox (denileukin), or pentostatin. Patients (n ‫؍‬ 180) were randomized; their median age was 50 years (range, 7.5-70 years). Myeloablative conditioning represented 66% of transplants. Grafts were peripheral blood (61%), bone marrow (25%), or umbilical cord blood (14%); 53% were from unrelated donors. Patients who received MMF for prophylaxis (24%) were randomized to a non-MMF arm. At randomization, aGVHD was grade I to II (68%), III to IV (32%), and (53%) had visceral organ involvement. Day 28 complete response rates were etanercept 26%, MMF 60%, denileukin 53%, and pentostatin 38%. Corresponding 9-month overall survival was 47%, 64%, 49%, and 47%, respectively.

Background Banked unrelated donor umbilical cord blood (CB) has improved access to hematopoietic stem cell transplantation for patients without a suitably matched donor. In a resource-limited environment, ensuring that the public inventory is enriched with high-quality cord blood units (CBUs) addressing the needs of a diverse group of patients is a priority. Identification of donor characteristics correlating with higher CBU quality could guide operational strategies to increase the yield of banked high-quality CBUs. Methods Characteristics of 5267 CBUs donated to the Carolinas Cord Blood Bank, a public bank participating in the National Cord Blood Inventory, were retrospectively analyzed. Eligible CBUs, collected by trained personnel, were processed using standard procedures. Routine quality and potency metrics [post-processing total nucleated cell count (post-TNCC), CD34+, colony-forming units (CFUs)] were correlated with maternal, infant, and collection characteristics. Results High-quality CBUs were defined as those with higher post-TNCC (>1.25×109), and CD34+ + CFU in the upper quartile. Factors associated with higher CD34+ or CFU content included a shorter interval from collection to processing (<10 hours), younger gestational age (34–37 weeks; CD34++CFU) Caucasian race, higher birth weight (>3500grams) and larger collection volumes (>80ml). Conclusions We describe characteristics identifying high-quality CBUs, which can be used to inform strategies for CBU collection for public banks. Efforts should be made to prioritize collections from larger babies born before 38 weeks of gestation. CBUs should be rapidly transported to the processing laboratory. The lower quality of CBUs from non-Caucasian donors highlights the challenges of building a racially diverse public CB inventory.

The complexity of chronic graft-versus-host disease (GVHD) and the lack of established research methods have made it difficult to design, conduct, and analyze clinical trials involving subjects with this disease, even when promising treatment options are available. This consensus document was developed to offer an approach for overcoming these obstacles. Clinical trials in chronic GVHD should adhere to principles of good trial design and practice. Inclusion and exclusion criteria should allow as many subjects to participate as possible without compromising the interpretation of results. Pre-enrollment assessment of chronic GVHD characteristics should be standardized. The protocol should provide clear guidance about administration of study medication and other interventions. Methods of assessing response should be defined and validated in advance. Efficacy endpoints should be selected to reflect clinical benefit. Expert biostatistical support is needed to ensure the validity and reliability of trial results. The use of consistent standards in clinical trial designs to evaluate agents that have activity in pathogenic pathways could facilitate advances in the treatment of chronic GVHD.