Double-unit Cord Blood Transplantation Research Articles

Total Donor Chimerism in the Day 21 Bone Marrow Predicts Sustained Donor Neutrophil Engraftment Following Double Unit Cord Blood Transplantation (CBT)

Total Donor Chimerism in the Day 21 Bone Marrow Predicts Sustained Donor Neutrophil Engraftment Following Double Unit Cord Blood Transplantation (CBT)

Reduced Late Mortality Risk Contributes to Similar Survival after Double-Unit Cord Blood Transplantation Compared with Related and Unrelated Donor Hematopoietic Stem Cell Transplantation

Cord blood transplantation (CB-T) is increasingly used as a treatment alternative for hematologic malignancies. However, how CB-T compares to related (RD-T) and unrelated donor transplantation (URD-T) is not established. We compared survival of 75 double-unit CB-T, 108 RD-T, and 184 URD-T recipients who received transplants over the same period for the treatment of hematologic malignancies. Patients had similar ages and disease risk, and a similar percentage had acute leukemia. The incidence of day 180 transplant-related mortality (TRM) of 21% (95% confidence interval [CI]: 12-31) after CB-T was higher than that of RD-T recipients. However, this was compensated for by a low risk of TRM after day 180, and a relatively low incidence of relapse. Hence, the 2-year progression-free survival (PFS) of 55% (95% CI: 45-68) after CB-T was similar to that after RD-T or URD-T (P = .573). In multivariate analysis, donor source had no influence on PFS, with the only significant factors being recipient age and disease risk. In a subanalysis of 201 patients with acute leukemia, CB-T, RD-T, and URD-T recipients also had similar 2-year disease-free survival (P = .482). These data provide strong support for the further investigation of double-unit CB grafts as an alternative hematopoietic stem cell source.

A Novel Reduced Intensity Conditioning Can Induce a High Incidence of Sustained Donor Engraftment After Double Unit Cord Blood Transplantation (CBT) without Anti-Thymocyte Globulin

AbstractAbstract 2351CBT can be curative for patients with high-risk hematologic malignancies. However, patients of older age, those with extensive prior therapy, or significant co-morbidities may not tolerate high-dose myeloablative conditioning. Reduced intensity (RI) or non-myeloablative (NMA) conditioning has been successfully used in CBT, especially in patients with lymphomas. However, patients with myeloid malignancies without extensive prior therapy have an increased risk of graft rejection following NMA CBT. Further, the addition of anti-thymocyte globulin (ATG) to enhance engraftment increases the risk of serious infections and Epstein-Barr virus post-transplant lymphoproliferative disease, and could increase the risk of relapse. Therefore, we investigated the efficacy and safety of a novel ATG-free RI conditioning prior to double unit CBT in patients with acute leukemias and myelodysplasia with the hypothesis that this regimen can induce a high incidence of sustained donor engraftment. Conditioning consisted of cyclophosphamide 50 mg/kg (day -6), fludarabine 30 mg/m2/day × 5 (days -6 to -2), thiotepa 5 mg/kg/day × 2 (days -5 and -4), and total body irradiation 200 cGy × 2 (days -2 and -1). All patients received cyclosporine-A and mycophenolate mofetil for graft-versus-host disease (GVHD) prophylaxis. Between 10/01/07-04/30/10, 20 patients were transplanted. The median age was 56 years (range 18–69). Thirteen (65%) had AML (9 CR1, 4 CR2), 4 (20%) had ALL (3 CR1, 1 CR3), and 3 (15%) had MDS (with one patient also having follicular lymphoma). The majority had high-risk disease. Indications for RI conditioning were the risk factors for transplant-related mortality (TRM) with high-dose conditioning of age ≥50 years, and/or extensive prior therapy, and/or significant co-morbidities. Thirteen patients had only 1 of these risk factors, whereas 7 had ≥2 risk factors. Units were predominantly 4–5/6 HLA-matched to the recipient (one 6/6, twenty-four 5/6, fifteen 4/6). The median infused cell doses of the larger units were 2.7 × 107 total nucleated cells/kg (range 1.46–5.56) and 0.95 × 105 CD34+ cells/kg (range 0.35–3.32), and 1.89 × 107/kg total nucleated cells/kg (range 1.42–2.47) and 0.59 × 105/kg CD34+ cells/kg (range 0.18–1.52) for the smaller units, respectively. The cumulative incidence of sustained donor engraftment at day 45 was 95% (95%CI: 81–100). The single patient with graft failure was 100% donor in the day 21 bone marrow, but died early post-transplant of multi-organ failure without count recovery. The median time to neutrophil recovery ≥0.5 × 109/l was 25 days (range 13–43). The median total donor chimerism in the day 21 bone marrow was 94% (both units combined, range 71–100), and sustained engraftment was accounted for by one unit in 18/19 engrafting patients. The incidence of grade II-IV acute GVHD at day 100 was 55% (95%CI: 32–78), and 46% (95%CI: 21–71) of patients have had late acute GVHD requiring ongoing therapy or chronic GVHD to date. The incidence of day 100 transplant-related mortality (TRM) was 20% (95%CI: 2–38). Notably, none of the 13 patients with only one risk factor died of transplant-related causes. By contrast, 5/7 (71%) patients with ≥2 risk factors died of TRM by day 100 (p=0.03, Table 1). Two additional patients died of relapse. With a median follow-up of 13 months (range 3–31), 1 year progression-free survival is 74% (95%CI: 55–94) (Figure 1). We demonstrate that this ATG-free RI conditioning is associated with a high incidence of sustained donor engraftment, and acceptable toxicities in older patients without other risk factors. While longer follow-up is needed, progression-free survival is encouraging provided multiple risk factors are not present. This conditioning combined with double unit grafts warrants further investigation, and may also be a promising alternative to high-dose conditioning in younger patients.Table 1Day 100 TRM according to number of risk factors (age ≥50 years, extensive prior therapy, significant co-morbidities).Risk FactorsDay 100 TRMP Value1 (N = 13)0/13 (0%)0.03≥2 (N = 7)5/7 (71%) [Display omitted] Disclosures:Giralt: Celgene: Honoraria, Speakers Bureau; Millenium: Honoraria, Speakers Bureau.

Vaccine Response In Recipients of HLA Mismatched Unrelated Double Unit Cord Blood Transplantation (CBT).

AbstractAbstract 1247The use of CBT has increased steadily over the last decade, with recent studies showing long-term progression-free survival similar to that of unrelated volunteer donor transplant recipients. The ability of CBT survivors to respond to post-transplant immunizations may differ from other allogeneic transplant populations due to the lack of transfer of memory T- and B-cells with the graft. Limited data have been reported on vaccine responses following this treatment modality. We, therefore, analyzed responses to immunizations in 23 double-unit CB recipients (17 adults, 6 children) transplanted at our center from 10/05-12/08. Patients were transplanted at a median age of 34 years (range 7–61) for the treatment of acute leukemia (n=13), or lymphoma/CLL (n=8/2). They received high-dose myeloablative (n=11), reduced intensity myeloablative (n=5), or non-myeloablative (n=7) conditioning according to diagnosis, age, prior therapy, and co-morbidities. GVHD prophylaxis consisted of a calcineurin inhibitor and mycophenolate mofetil. No patient received ATG. The study patients had sustained engraftment with a 5/6 (n=12) or 4/6 (n=11) HLA-matched unit. Seven recipients received rituximab (median 4 doses, range: 4–8) as planned post-transplant therapy for B-cell malignancies (n=6) or treatment of an autoimmune hemolytic anemia (n=1). Eleven patients had a history of grade II-IV acute GVHD and 5 had ongoing late acute or chronic GVHD prior to vaccination. Criteria for vaccination were: CD4 cell count of at least 200 cells/ul, PHA of greater than 60% lower limit of normal and serum IgG level >500 mg/dl at least 6 weeks following the last dose of IVIG. The median time to vaccination was 1.26 years post-CBT; this time was significantly longer in patients treated with Rituximab compared to those who were not (1.6 years versus 1.2 years, p=0.02), due to delayed normalization of B-cell numbers in the former group (449 days vs 108 days, p=0.004).Pre-vaccination titers obtained at a median of 1 year post-CBT demonstrated that over 85% of patients lacked protection against Pneumococcus, H. influenzae, and Pertussis, and at least 50% lacked immunity against tetanus, measles, and mumps. Seroconversion or >3- fold rise in titer was observed in response to tetanus, diphtheria, H. influenzae, and Pneumococcus in 90% (18/20), 81% (13/16), 80% (16/20)and 90% (18/20) of patients and was not significantly different in patients with or without a history of acute or chronic GVHD. Whereas 90% (5/6) of patients without a history of GVHD responded to a series of Hepatitis B immunizations, only 22% (2/9) of those with prior acute and/or chronic GVHD did so (p=0.03). No patient was protected against pertussis following a single TDaP (n=14) and only 1 of 5 patients responded to the protein conjugated meningococcal vaccine. Immunization with a live attenuated vaccine was initiated in 7 seronegative patients, including all 6 children, at a median of 2.25 years (range 1.5–3.6) post-CBT (MMR, n=7, Varivax, n=3). Seroconversion against measles, mumps, rubella, or chickenpox was observed in 3/7, 2/7, 6/7, and 1/3 patients, respectively. There were no serious reactions to any vaccine. These data suggest that CBT recipients are capable of responding to tetanus, diphtheria, H. Influenza and pneumococcal vaccines similar to other transplant groups. Nonetheless, the sub-optimal response to pathogens associated with outbreaks in the community (Hepatitis B, Pertussis, meningococcus, measles, mumps, varicella) highlight the need to obtain pre- and post-vaccination titers to document response, as well as define the optimal schedule of post-transplant immunizations specifically in this transplant population. Disclosures:No relevant conflicts of interest to declare.

Unrelated Cord Blood Transplantation: Comparison After Single Unit Cord Blood Intrabone Injection and Double Unit Cord Blood Transplantation In Patients with Hematological Malignant Disorders. A Eurocord-EBMT Analysis

AbstractAbstract 223The use of single cord blood unit for transplantation in adult patients is limited due to the high risk of graft failure and delayed neutrophil and platelet recoveries. The limited hematopoietic progenitors in UCB grafts and their homing after IV injection, have prompted investigators to study the design of delivering CB grafts directly into the bone marrow (BM) space (IBCBT) or to use double cord blood transplantation (dUCBT) to improve engraftment. To evaluate the impact of IBCBT, we made a retrospective based registry comparison with dUCBT performed in the same time period (2006-2010) and reported to Eurocord-EBMT. We included 87 and 149 patients who received either IBCBT or dUCBT, respectively, after a myeloablative conditioning regimen for malignant disorders. IBCBT was performed in 8 EBMT centers whereas dUCBT was performed in 56 EBMT centers. Majority of patients in both groups had acute leukemia. IBCBT patients were older (p<0.001), more frequently received an autologous graft (p<0.001) and had positive CMV serology (p<0.001), and importantly had more advanced disease at transplantation (p=0.04). Median number of infused (after thawing) nucleated cells injected intrabone was 2.5×107/kg and it was 3.9×107/kg in dUCBT (p<0.001). In 72% of both groups, CB grafts were HLA 4/6 (the highest HLA disparity was taken into consideration in dUCBT). Other differences were regarding GVHD prophylaxis that was based on CSA+MMF in 100% of IBCBT and in 62% of dUCBT cases; ATG was used in all IBCBT and 40% of dUCBT. Median follow-up time was 18 months in IBCBT and 17 months in dUCBT. At day 30, cumulative incidence (CI) of neutrophil recovery (ANC >500) was 83% after IBCBT and 63% after dUCBT, and at day 60, it was 90% in both groups; the median time to reach ANC>500 was 23 and 28 days after IBCBT and after dUCBT (p=0.001) respectively. At Day-180 CI of platelets recovery was 81% after IBCBT and 65% after dUCBT (p<0.001) with a median time of 36 days and 49 respectively (p=0.002). At day 100, CI of acute GVHD (II-IV) was 19% and 47% (p<0.001) and chronic GVHD 34% and 37% respectively (p=NS) respectively. Unadjusted 2 years-CI of NRM and RI were 31% and 23% after IBCBT and 35% and 28% after dUCBT, respectively (p=NS). Unadjusted 2 y-DFS estimation was 47% after IBCBT and 37% after dUCBT (p=NS). In multivariate analysis adjusting for statistical differences between 2 groups (such as status of the disease at transplant, age, CMV, previous transplants, GVHD prophylaxis), recipients of IBCBT had improved DFS (HR: 1.64, p=0.035), faster platelet recovery (HR:2.13, p<0.001) and decreased acute GVHD (HR:0.31; p<0.001) compared to dUCBT recipients. We did not find a cut-off value of number of nucleated cells after IBCBT or dUCBT that could be associated with outcomes after both approaches. In conclusion, both strategies have extended the use of CB transplants to adults in need of cord blood transplantation. Therefore, IBCBT is an option to transplant adult patients with single CB units after myeloablative conditioning regimen and may impact the total costs of cord blood transplantation. Based on these results, intra-bone technique may disclose new transplant potentialities also with other HSC sources. Disclosures:No relevant conflicts of interest to declare.

The Use of Double-Unit Umbilical Cord Blood Transplantation In Adults with Hematologic Disease.

AbstractAbstract 4579 Objective:In this study, we explored the efficiency and toxicity of 38 cases of double-unit umbilical cord blood transplantation (CBT) in adults with hematologic disease. Methods:The tolerance; transplant related complications; survival rate and disease free survival rate were observed and analyzed. A nonmyeloablative conditioning regimen included cyclophosphamide, fludarabine and 2Gy TBI. Cyclosporine combined mycophenolate mofetil and ATG were used to prevent graft versus host disease (GVHD). Results:All these 38 patients tolerated the therapy well while two patients had graft failure. Severe acute GVHD was presented in 6 patients. Chronic GVHD was occurred in 16 patients. Fatal infection complications were occurred in 5 patients (including CMV idiopathic pneumonia in 2 patients) and 4 patients relapsed after transplantation. Neutrophil engraftment obtained on day +17 and platelet reconstitution occurred on day +42 on median. In the follow-up duration of 17 months on median, the expected 2-year relapse mortality was 17.95%; non-relapse mortality was 25.90%; overall survival was 60.80%, and disease free survival was 52.11%. Compare with 39 cases of haplo-identical HSCT in our department, significant delays in engraftment and lower severe GVHD occurred after CBT. There was no apparent difference between the risk of relapse and DFS in both groups. Conclusion:The use of double-unit CBT after reduced intensive conditioning therapy in adults with hematologic disease is an effective and safe treatment. Fatal infection and relapse are the main reasons of failure. Disclosures:No relevant conflicts of interest to declare.

An in vivo model of double-unit cord blood transplantation that correlates with clinical engraftment

AbstractDouble-unit cord blood transplantation (DCBT) appears to enhance engraftment despite sustained hematopoiesis usually being derived from a single unit. To investigate DCBT biology, in vitro and murine models were established using cells from 39 patient grafts. Mononuclear cells (MNCs) and CD34+ cells from each unit alone and in DCB combination were assessed for colony-forming cell and cobblestone area-forming cell potential, and multilineage engraftment in NOD/SCID/IL2R-γnull mice. In DCB assays, the contribution of each unit was measured by quantitative short tandem repeat region analysis. There was no correlation between colony-forming cell (n = 10) or cobblestone area-forming cell (n = 9) numbers and clinical engraftment, and both units contributed to DCB cocultures. In MNC transplantations in NOD/SCID/IL2R-γnull mice, each unit engrafted alone, but MNC DCBT demonstrated single-unit dominance that correlated with clinical engraftment in 18 of 21 cases (86%, P < .001). In contrast, unit dominance and clinical correlation were lost with CD34+ DCBT (n = 11). However, add-back of CD34− to CD34+ cells (n = 20) restored single-unit dominance with the dominant unit correlating not with clinical engraftment but also with the origin of the CD34− cells in all experiments. Thus, unit dominance is an in vivo phenomenon probably associated with a graft-versus-graft immune interaction mediated by CD34− cells.

Cord blood transplants: one, two or more units?

This review summarizes the current status of double-unit cord blood transplantation (CBT) to improve engraftment, reduce transplant-related mortality, and improve disease-free survival. Transplantation of cord blood provides a potentially curative therapy for many patients without a suitably human leukocyte antigen-matched related or unrelated donor. Single-unit CBT outcomes have been compromised, however, in adults and larger children by limited cell dose. The introduction of double-unit CBT has improved engraftment and transplant-related mortality in adult patients transplanted for hematologic malignancies, with recent data also suggesting a protection against relapse. These improved outcomes are seen despite only a single unit being responsible for sustained donor hematopoiesis in nearly all patients. The study of double-unit CBT provides unique insights into transplant biology, with emerging data suggesting unit dominance is related to unit viability and unit-versus-unit immune interactions. Multiple unit CBT further serves as a platform to test novel graft manipulations. The development of double-unit CBT now allows the majority of patients, regardless of size or racial/ethnic background, access to transplant therapy. Ongoing investigation will serve to further improve outcomes and expand the role of CBT in the future.

Effect of parity on fetal and maternal microchimerism: interaction of grafts within a host?

AbstractSmall amounts of genetically foreign cells (microchimerism, Mc) traffic between a mother and fetus during pregnancy. Commonly, these grafts durably persist. For women, multiple naturally acquired Mc grafts can accrue, as they harbor Mc from their own mothers (maternal Mc, MMc) and subsequently acquire fetal Mc (FMc) through pregnancy. The nature of interactions between these naturally acquired grafts may inform, and be informed by, observations in transplantation, including the effect of noninherited maternal HLA antigens (NIMA) and double-unit cord blood transplantation (CBT). We asked whether FMc and MMc are impacted by the addition of new grafts as evaluated by increasing parity. Mc was identified by quantitative PCR for a nonshared polymorphism unique to the Mc source. Despite increasing sources of Mc, FMc did not increase with increasing parity. MMc concentration was significantly lower with increasing parity. The odds ratio for detection of MMc for 2 or more births compared with 1 birth was .11 (95% CI 0.03-0.42, P = .001). These observations suggest that interactions occur among naturally acquired grafts and are of interest in light of recent observations of graft-graft interaction resulting in predominance of 1 unit in double-unit CBT and the correlation of MMc with the NIMA effect.

Double unit cord blood transplantation

Double unit cord blood transplantation (DUCBT) has emerged as a successful strategy to improve engraftment and decrease transplant related mortality in adults and large children undergoing cord transplantation. In the vast majority of cases, one unit emerges as the sole source of long term hematopoiesis in the recipient following DUCBT. No factors have been identified that reliably predict which unit will emerge as the dominant unit, and limited studies have examined the mechanism underlying the observation. In a recent publication in Blood, we provide the first compelling data that effector CD8(+) T cells play a critical role in the dominant unit actively rejecting the losing unit. Our findings provide an important first step in understanding the interactions following DUCBT, and provide insights that might be used to optimize graft versus leukemia effect and cord unit selection as well as better understand mechanisms of tolerance.

Clearance of CMV viremia and survival after double umbilical cord blood transplantation in adults depends on reconstitution of thymopoiesis

Umbilical cord blood grafts are increasingly used as sources of hematopoietic stem cells in adults. Data regarding the outcome of this approach in adults are consistent with delayed and insufficient immune reconstitution resulting in high infection-related morbidity and mortality. Using cytomegalovirus (CMV)-specific immunity as a paradigm, we evaluated the status, mechanism, and clinical implications of immune reconstitution in adults with hematologic malignancies undergoing unrelated double unit cord blood transplantation. Our data indicate that CD8(+) T cells capable of secreting interferon-gamma (IFN-gamma) in a CMV-specific enzyme-linked immunosorbent spot (ELISpot) assay are detectable at 8 weeks after transplantation, before reconstitution of thymopoiesis, but fail to clear CMV viremia. Clearance of CMV viremia occurs later and depends on the recovery of CD4(+)CD45RA(+) T cells, reconstitution of thymopoiesis, and attainment of T-cell receptor rearrangement excision circle (TREC) levels of 2000 or more copies/mug DNA. In addition, overall survival was significantly higher in patients who displayed thymic regeneration and attainment of TREC levels of 2000 or more copies/mug DNA (P = .005). These results indicate that reconstitution of thymopoiesis is critical for long-term clinical outcome in adult recipients of umbilical cord blood transplant. The trial was prospectively registered at http://www.clinicaltrials.gov (NCT00133367).

Clathrin Assembly Lymphoid Myeloid Leukemia-AF10-positive Acute Leukemias: A Report of 2 Cases with a Review of the Literature

The translocation t(10;11)(p13;q14q21) has been found to be recurrent in acute lymphoblastic and myeloid leukemias, and results in the fusion of the clathrin assembly lymphoid myeloid leukemia (CALM) gene with the AF10 gene; these genes are present on chromosomes 11 and 10, respectively. Because the CALM-AF10 rearrangement is a rare chromosomal abnormality, it is not included in routine molecular tests for acute leukemia. Here, we describe the cases of 2 patients with the CALM-AF10 fusion gene. The first patient (case 1) was diagnosed with T-cell ALL, and the second patient (case 2) was diagnosed with AML. Both patient samples showed expression of the homeobox A gene cluster and the histone methyltransferase hDOT1L, which suggests that they mediate leukemic transformation in CALM-AF10-positive and mixed-lineage leukemia-AF10-positive leukemias. Both patients achieved complete remission after induction chemotherapy. The first patient (case 1) relapsed after double-unit cord blood transplantation; there was no evidence of relapse in the second patient (case 2) after allogenic peripheral blood stem cell transplantation. Since CALM-AF10- positive leukemias have been shown to have poor prognosis with conventional therapy, molecular tests for CALM-AF10 rearrangement would be necessary to detect minimal residual disease during follow-up.

A Preclinical Model of Double- versus Single-Unit Unrelated Cord Blood Transplantation

Cord blood transplantation (CBT) with units containing total nucleated cell (TNC) dose >2.5 x 10(7)/kg is associated with improved engraftment and decreased transplant-related mortality. For many adults no single cord blood units are available that meet the cell dose requirements. We developed a dog model of CBT to evaluate approaches to overcome the problem of low cell dose cord blood units. This study primarily compared double- versus single-unit CBT. Unrelated dogs were bred and cord blood units were harvested. We identified unrelated recipients that were dog leukocyte antigen (DLA)-88 (class I) and DLA-DRB1 (class II) allele-matched with cryopreserved units. Each unit contained <or=1.7 x 10(7) TNC/kg. Recipients were given 9.2 Gy total-body irradiation (TBI) and DLA-matched unrelated cord blood with postgrafting cyclosporine and mycophenolate mofetil. After double-unit CBT, 5 dogs engrafted and 4 survived long term with 1 dominant engrafting unit and prompt immune reconstitution. In contrast, 0 of 5 dogs given single-unit CBT survived beyond 105 days (P = .03, log-rank test); neutrophil and platelet recovery was delayed (both P = .005) and recipients developed fatal infections. This new large animal model showed that outcomes were improved after double-unit compared to single-unit CBT. After double-unit CBT, the nonengrafted unit facilitates engraftment of the dominant unit.

Single-unit dominance after double-unit umbilical cord blood transplantation coincides with a specific CD8+ T-cell response against the nonengrafted unit

AbstractWe investigated the potential role of an immune reaction in mediating the dominant engraftment of 1 cord blood unit in 14 patients who received a double-unit cord blood transplantation (CBT). In 10 patients, dominant engraftment of a single donor unit emerged by day 28 after CBT. In 9 of these 10 patients, a significant subset of CD8+ CD45RO+/−CCR7− T cells, present in peripheral blood mononuclear cells and derived from the engrafting cord blood unit, produced interferon-γ (IFN-γ) in response to the nonengrafting unit. No significant population of IFN-γ–secreting cells was detectable when posttransplantation peripheral blood mononuclear cells were stimulated against cells from the engrafted unit (P < .001) or from a random human leukocyte antigen disparate third party (P = .003). Three patients maintained persistent mixed chimerism after CBT, and no significant IFN-γ–secreting cells were detected after similar stimulations in these patients (P < .005). Our data provide the first direct evidence in human double-unit CBT recipients that immune rejection mediated by effector CD8+ T cells developing after CBT from naive precursors is responsible for the failure of 1 unit to engraft. Future investigations based on these findings may result in strategies to predict a dominant unit and enhance graft-versus-leukemia effect.

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.

Second transplant with two unrelated cord blood units for early graft failure after cord blood transplantation for thalassemia

Early GF is a frequent complication following hematopoietic stem cell transplantation for patients with thalassemia. We report the outcome of double-unit CBT in three patients who developed early GF after CBT. The initial conditioning regimen consisted of i.v. Bu 14 mg/kg (day -9 to -6), i.v. Cy 200 mg/kg (day -5 to -2) and ATG at 120 mg/kg (day -4 to -1). They received GVHD prophylaxis with cyclosporine-A from day -3 and a short course of methylprednisolone (1 mg/kg i.v., every 12 h on days 5-19 with a taper, thereafter 25% decrease every other day). The interval between two transplants was seven and 10 months. The retransplant recipients were preconditioned with i.v. Bu 14 mg/kg (day -7 to -4), i.v. Cy 120 mg/kg (day -3 to -2) and ATG at 150 mg/kg (day -5 to -1 and +1 to +5). GVHD prophylaxis regimen was the same as the first transplant. Neutrophil engraftment were observed in all patients between day +15 and +26. All are alive, between nine and 11 months after retransplant. Our group reported successful utilization of double umblical cord blood grafts in thalassemia patients with early GF.

Pre-Engraftment Syndrome (PES): A Clinical Syndrome After Cord Blood (CB) Transplantation Not Associated with Acute Graft-Versus-Host Disease (aGvHD) or Transplant-Related Mortality (TRM)

Pre-Engraftment Syndrome after cord blood transplantation (CBT) is poorly characterized. Therefore, we conducted a review of 52 double unit CBT recipients treated for high-risk hematological malignancies to determine the incidence, manifestations, and outcomes of PES. PES was defined as unexplained fever >38.3ºC (101ºF) unresponsive to antibiotics and/or unexplained skin rash resembling aGVHD occurring prior to or at neutrophil recovery. CBT recipients [median 38 years (range 3–66)] received either ablative (n = 36) or non-myeloablative (NMA, n = 16) conditioning and CSA/MMF.

Pre-freeze and post-thaw characteristics on chimerism patterns in double-unit cord blood transplantation

We analyzed the pre-freeze and post-thaw characteristics on chimerism patterns in 20 cases of double-unit cord blood transplantation. The cord blood units (CBUs) were a 4/6 HLA match or better with recipients and achieved a minimum combined precryo-preservation cell dose of 3.7 x 10(7) total nucleated cell (TNC)/kg. The unit with a higher cell dose was infused first. All evaluable patients engrafted at a median of 18 days. By day 42, neutrophil engraftment was derived from both donors in 63% of cases and a single donor in 37% of patients. By day 100, one unit predominated in 80% of the patients. Higher pre-freeze TNC and CD34+ cell doses were associated with cord predominance in 67% of patients.

Decreased Relapse Rates without Excessive Transplant Related Mortality Following Cord Blood Transplantation (CBT): A Matched Cohort Analysis Comparing Myeloablative Cord, Matched Unrelated, and Mismatched Unrelated Donor Transplants.

We conducted a matched cohort analysis comparing relapse rates and outcomes for patients receiving transplants from cord blood, matched unrelated donors, and mismatched unrelated donors following myeloablative conditioning in our center's recent experience. Between April 2006, when our current cord blood protocols opened, and February 2008, 26 consecutive patients underwent CBT following conditioning with 13.2 Gy TBI, 120 mg/kg cyclophosphamide (CY), and 75 mg/m2 fludarabine (FLU) for acute leukemias in morphologic CR (n=24) or chronic myeloid leukemia not in blast crisis (n=2). Twenty-three patients received two units (5 of whom had one of the two units ex vivo expanded) and three received single units. Matching between units and patient was 4/6:4/6 (n=10), 4/6:5/6 (n=5), 5/6:5/6 (n=7), 6/6:6/6 (n=1), and single 5/6 (n=3). For paired analysis with each cord patient, waiver of consent was obtained from the IRB and one matched 10/10 unrelated donor patient (MURD) and one mismatched (9/10 n=23, 8/10 n=3) unrelated donor patient (MMURD) was selected from our center's database on the basis of identical disease status and similar age without knowledge of transplant outcome. All unrelated donor patients underwent myeloablative transplantation following conditioning with CY/TBI or busulfan (BU)/CY between November 2001 and February 2008 (median April 2005). Patients were matched for disease type, cytogenetic risk status, minimal residual disease status (MRD), and, for patients beyond CR1, time from diagnosis to relapse. Specific diseases and disease status were ALL n=10: CR1 n=8 (MRD n=3), CR2 n=1, CR3 n=1 (MRD n=1), Philadelphia chromosome positive n=3; AML n=14: CR1 n=8 (MRD n=1), CR2 n=6 (MRD n=2); CML n=2 (CP1 n=1, CP2 following blast crisis n=1). Median ages and range for patients were: CBT 23 (0.6–42), MURD 25 (1–41), and MMURD 25 (1–48), and median differences in age between the cord recipient and their unrelated donor matched pairs were 7.8 and 4.6 years for MMURD and MURD, respectively. Median follow-up for surviving cord patients is 16 months (range 7.5–26). There has been only 1 relapse among cord patients versus 8 relapses among MURDs and 5 relapses among MMURDs. Transplant related mortality (TRM) between each group is comparable. Cause specific hazard for relapse is significantly decreased when comparing cords to MURDs by logrank test (p=0.014) and trends toward decrease when comparing cords to MMURDs (p=0.068) (Figure 1). Two year cumulative incidence (CI) of relapse is 3.8% (95% CI 0.3–16.4) for cord patients, 31.4% (95% CI 14.9–49.6) for MURDs, and 21% (95% CI 7.6–38.9) for MMURDs. Two year CI of TRM is 21.6% (95% CI 7.5–40.4) for cord patients, 22.9% (95% CI 8.3–41.8) for MURDs, and 31.8% (95% CI 15–50.1) for MMURDs. Previous data suggest that double unit CBT, as compared to single unit CBT, may markedly reduce relapse rates. The majority of CBT patients included in this analysis underwent double unit CBT, and this strategy may contribute to our observations. Additionally, myeloablative MURD and MMURD TBI regimens at our center involve 12 Gy in contrast to the 13.2 Gy in our CBT regimens. This may also account to some degree for lower relapse rates. Larger numbers and longer follow-up will be needed to confirm these observations, but the possibility of decreased relapse rates without increased TRM is promising. Growing inventories of high quality cord blood units coupled with ongoing improvements in supportive care for CBT patients should lead to continued expansion of the role of CBT. [Display omitted]