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Total Colony-Forming Units Are a Strong, Independent Predictor of Neutrophil and Platelet Engraftment after Unrelated Umbilical Cord Blood Transplantation: A Single-Center Analysis of 435 Cord Blood Transplants

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.

Outcomes of transplantation using various hematopoietic cell sources in children with Hurler syndrome after myeloablative conditioning.

We report transplantation outcomes of 258 children with Hurler syndrome (HS) after a myeloablative conditioning regimen from 1995 to 2007. Median age at transplant was 16.7 months and median follow-up was 57 months. The cumulative incidence of neutrophil recovery at day 60 was 91%, acute graft-versus-host disease (GVHD) (grade II-IV) at day 100 was 25%, and chronic GVHD and 5 years was 16%. Overall survival and event-free survival (EFS) at 5 years were 74% and 63%, respectively. EFS after HLA-matched sibling donor (MSD) and 6/6 matched unrelated cord blood (CB) donor were similar at 81%, 66% after 10/10 HLA-matched unrelated donor (UD), and 68% after 5/6 matched CB donor. EFS was lower after transplantation in 4/6 matched unrelated CB (UCB) (57%; P = .031) and HLA-mismatched UD (41%; P = .007). Full-donor chimerism (P = .039) and normal enzyme levels (P = .007) were higher after CB transplantation (92% and 98%, respectively) compared with the other grafts sources (69% and 59%, respectively). In conclusion, results of allogeneic transplantation for HS are encouraging, with similar EFS rates after MSD, 6/6 matched UCB, 5/6 UCB, and 10/10 matched UD. The use of mismatched UD and 4/6 matched UCB was associated with lower EFS.

Optimizing donor selection for public cord blood banking: influence of maternal, infant, and collection characteristics on cord blood unit quality

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.

Posttransplant Autoimmune Hemolytic Anemia and Other Autoimmune Cytopenias are Increased in Very Young Infants Undergoing Unrelated Donor Umbilical Cord Blood Transplantation

Autoimmune cytopenias are a recognized complication of hematopoietic stem cell transplant (HSCT), and are considered to be a feature of chronic graft-versus-host disease (cGVHD). We report on a cohort of very young infants (< or =3 months of age) receiving HSCT from unrelated donor umbilical cord blood for genetic disorders who developed posttransplant autoimmune cytopenias at an increased rate compared to older aged controls. These infants received a conditioning regimen consisting of busulfan, cyclophosphamide, and antithymocyte globulin (ATG). All infants received HLA mismatched unrelated umbilical cord blood as graft source. GVHD prophylaxis was either cyclosporine + methylprednisolone (n = 16) or cyclosporine + mycophenolate mofetil (n = 3). Engraftment, acute GVHD (aGVHD) and cGVHD, survival, treatment-related mortality (TRM), and deaths were evaluated. Ten patients developed cGVHD manifesting as autoimmune cytopenias at a median 247 days posttransplant with a cumulative incidence of 44% (95% confidence interval [CI] 21%-68%) and 56% (95% CI 32%-80%) at 1 and 2 years, respectively. In 6 of 10 patients developing autoimmune cytopenias, cGVHD presented as autoimmune cytopenia de novo. The cytopenias observed included anemia (n = 4), thrombocytopenia (n = 1), anemia with thrombocytopenia (n = 3), and pancytopenia (n = 2). No graft factors were identified as being significant to development of cGVHD. All patients responded to treatment with methylprednisolone, azithioprine +/- rituximab. One patient required splenectomy. We hypothesize that posttransplant immunosuppression interferes with normal immune ontogeny creating immune dysregulation and graft directed cell destruction. Alternative strategies to prevent GVHD should be considered for this unique patient population.

The Cord Blood Apgar: a novel scoring system to optimize selection of banked cord blood grafts for transplantation (CME)

BACKGROUND: Engraftment failure and delays, likely due to diminished cord blood unit (CBU) potency, remain major barriers to the overall success of unrelated umbilical cord blood transplantation (UCBT). To address this problem, we developed and retrospectively validated a novel scoring system, the Cord Blood Apgar (CBA), which is predictive of engraftment after UCBT.

A novel reduced-intensity conditioning regimen for unrelated umbilical cord blood transplantation in children with nonmalignant diseases.

Reduced-intensity conditioning (RIC) regimens have the potential to decrease transplantation-related morbidity and mortality. However, engraftment failure has been prohibitively high after RIC unrelated umbilical cord blood transplantation (UCBT) in chemotherapy-naïve children with nonmalignant diseases (NMD). Twenty-two children with a median age of 2.8 years, many with severe comorbidities and prior viral infections, were enrolled in a novel RIC protocol consisting of hydroxyurea, alemtuzumab, fludarabine, melphalan, and thiotepa followed by single UCBT. Patients underwent transplantation for inherited metabolic disorders (n = 8), primary immunodeficiencies (n = 9), hemoglobinopathies (n = 4) and Diamond Blackfan anemia (n = 1). Most umbilical cord blood (UCB) units were HLA-mismatched with median infused total nucleated cell dose of 7.9 × 10(7)/kg. No serious organ toxicities were attributable to the regimen. The cumulative incidence of neutrophil engraftment was 86.4% (95% confidence interval [CI], 65% to 100%) in a median of 20 days, with the majority sustaining > 95% donor chimerism at 1 year. Cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV by day 180 was 27.3% (95% CI, 8.7% to 45.9%) and 13.6% (95 CI, 0% to 27.6%), respectively. Cumulative incidence of extensive chronic GVHD was 9.1% (95% CI, 0% to 20.8%). The primary causes of death were viral infections (n = 3), acute GVHD (n = 1) and transfusion reaction (n = 1). One-year overall and event-free survivals were 77.3% (95% CI, 53.7% to 89.8%) and 68.2% (95% CI, 44.6% to 83.4%) with 31 months median follow-up. This is the first RIC protocol demonstrating durable UCB engraftment in children with NMD. Future risk-based modifications of this regimen could decrease the incidence of viral infections. (www.clinicaltrials.gov/NCT00744692).

Development and validation of a rapid, aldehyde dehydrogenase bright–based cord blood potency assay

Banked, unrelated umbilical cord blood provides access to hematopoietic stem cell transplantation for patients lacking matched bone marrow donors, yet 10% to 15% of patients experience graft failure or delayed engraftment. This may be due, at least in part, to inadequate potency of the selected cord blood unit (CBU). CBU potency is typically assessed before cryopreservation, neglecting changes in potency occurring during freezing and thawing. Colony-forming units (CFUs) have been previously shown to predict CBU potency, defined as the ability to engraft in patients by day 42 posttransplant. However, the CFU assay is difficult to standardize and requires 2 weeks to perform. Consequently, we developed a rapid multiparameter flow cytometric CBU potency assay that enumerates cells expressing high levels of the enzyme aldehyde dehydrogenase (ALDH bright [ALDH(br)]), along with viable CD45(+) or CD34(+) cell content. These measurements are made on a segment that was attached to a cryopreserved CBU. We validated the assay with prespecified criteria testing accuracy, specificity, repeatability, intermediate precision, and linearity. We then prospectively examined the correlations among ALDH(br), CD34(+), and CFU content of 3908 segments over a 5-year period. ALDH(br) (r = 0.78; 95% confidence interval [CI], 0.76-0.79), but not CD34(+) (r = 0.25; 95% CI, 0.22-0.28), was strongly correlated with CFU content as well as ALDH(br) content of the CBU. These results suggest that the ALDH(br) segment assay (based on unit characteristics measured before release) is a reliable assessment of potency that allows rapid selection and release of CBUs from the cord blood bank to the transplant center for transplantation.

Umbilical Cord Blood Transplantation to Treat Pelizaeus-Merzbacher Disease in 2 Young Boys

Pelizaeus-Merzbacher Disease (PMD) is a rare X-linked recessive leukodystrophy caused by mutations in the proteolipid protein 1 gene on the Xq22 chromosome. PMD is a dysmyelinating disorder characterized by variable clinical presentation and course. Symptoms range from mild motor deficits to progressive spasticity and neurologic decline resulting in death at an early age. There is no definitive curative treatment. This report presents the clinical course of 2 young boys with PMD who are the first known patients to receive umbilical cord blood transplantation as a therapeutic intervention to stabilize disease progression. Pretransplantation evaluation revealed that both patients had significant motor deficits as well as delayed cognitive function as compared with age-matched peers. Brain imaging revealed varying degrees of hypomyelination. Both patients received myeloablative chemotherapy followed by an unrelated donor umbilical cord blood infusion, which they tolerated well with no major transplantation-related complications. At 7-years and 1-year posttransplantation, respectively, both boys are making slow neurocognitive improvements and show no evidence of functional decline. Imaging results show stable or improving myelination. Although the results of unrelated donor umbilical cord blood transplantation in these 2 boys with PMD are encouraging, longer-term follow-up will be necessary to assess the effect of this treatment on the variable natural disease course.

Haploidentical Bone Marrow Transplantation with Post-Transplant Cyclophosphamide for Children and Adolescents with Fanconi Anemia

We describe haploidentical bone marrow transplantation with post-transplant cyclophosphamide (PT-CY) for 30 patients with Fanconi anemia (FA). Twenty-six patients were transplanted upfront, and the preparatory regimens included fludarabine 150 mg/m2 + total body irradiation 200 to 300 cGy ± CY 10 mg/kg without (n = 12) or with rabbit antithymocyte globulin (r-ATG) 4 to 5 mg/kg (n = 14). Four patients were rescued after primary or secondary graft failure after related or unrelated donor transplantation with the above regimen with (n = 2) or without r-ATG (n = 2). PT-CY at 25 mg/kg/day (total dose, 50 mg/kg) followed by cyclosporine and mycophenolate mofetil was given to all patients. All patients engrafted in the subgroup of patients who did not receive r-ATG (n = 14), but their transplant course was complicated by high rates of acute and chronic graft-versus-host disease (GVHD), and only 8 patients are alive. In the subgroup that received r-ATG (n = 16), 14 patients had sustained engraftment, severe GVHD rates were lower, and 13 patients are alive. Hemorrhagic cystitis occurred in 50% of patients, whereas cytomegalovirus reactivation occurred in 75%. One-year overall survival for the entire cohort was 73% (95% CI, 64% to 81%), and all surviving patients achieved full donor chimerism. In conclusion, haploidentical donor transplantation with PT-CY is a suitable option for FA patients without a matched related or unrelated donor.

Hematopoietic Stem Cell Transplantation Activity in Pediatric Cancer between 2008 and 2014 in the United States: A Center for International Blood and Marrow Transplant Research Report

This Center for International Blood and Marrow Transplant Research report describes the use of hematopoietic stem cell transplantation (HSCT) in pediatric patients with cancer, 4408 undergoing allogeneic (allo) and3076 undergoing autologous (auto) HSCT in the United States between 2008 and 2014. In both settings, there was a greater proportion of boys (n = 4327; 57%), children < 10 years of age (n = 4412; 59%), whites (n = 5787; 77%), and children with a performance score ≥ 90% at HSCT (n = 6187; 83%). Leukemia was the most common indication for an allo-transplant (n = 4170; 94%), and among these, acute lymphoblastic leukemia in second complete remission (n = 829; 20%) and acute myeloid leukemia in first complete remission (n = 800; 19%) werethe most common. The most frequently used donor relation, stem cell sources, and HLA match were unrelated donor (n = 2933; 67%), bone marrow (n = 2378; 54%), and matched at 8/8 HLA antigens (n = 1098; 37%) respectively. Most allo-transplants used myeloablative conditioning (n = 4070; 92%) and calcineurin inhibitors and methotrexate (n = 2245; 51%) for acute graft-versus-host disease prophylaxis. Neuroblastoma was the most common primary neoplasm for an auto-transplant (n = 1338; 44%). Tandem auto-transplants for neuroblastoma declined after 2012 (40% in 2011, 25% in 2012, and 8% in 2014), whereas tandem auto-transplants increased for brain tumors (57% in 2008 and 77% in 2014). Allo-transplants from relatives other than HLA-identical siblings doubled between 2008 and 2014 (3% in 2008 and 6% in 2014). These trends will be monitored in future reports of transplant practices in the United States.