Double Cord Blood Transplantation Research Articles

The Risk of Day 100 Mortality Following Umbilical Cord Blood Transplantation Is Significantly Higher in Patients Who Do Not Achieve An ANC of 100 by Day +16 Post Transplant

Abstract 3033Background: Cord blood transplant (CBT) recipients have higher infection-related morbidity and mortality than recipients of other stem cells sources following allogeneic transplant due to delayed hematopoietic recovery and immune reconstitution. Even in recipients of myeloablative (MA) double cord blood transplant (dCBT), time to engraftment (defined as the first of two consecutive days with an absolute neutrophil count (ANC) ≥ 500/μl) is delayed more than three weeks resulting in higher rates of infection in the first 100 days post-transplant. However, a better understanding of the relationship between duration of neutropenia and risk of early transplant related mortality is needed to assess the clinical impact of methodologies aimed at reducing neutropenia post transplant. Previously, the relationship between severe neutropenia (ANC ≤ 100/μl) and risk of death was evaluated for allogeneic bone marrow transplant recipients using proportional hazards models and demonstrated a significantly increased risk for those with severe neutropenia at day 15 or beyond following transplantation (Offner et al, Blood, 1996; 88(10): 4058–62). Here we use a similar model to determine how duration of severe neutropenia relates to risk of death following CBT. Methods: All patients (n=137) who received a CBT on a research protocol at a single institution from 2006–2010 were eligible. On each day from day 0 to day +100, surviving patients were divided into those with ANC ≤ 100/μl and those with ANC >100/μl and the number of patients who died by day +100 determined for each group. Hazard ratios (HR) with 95% confidence intervals for day +100 mortality were then calculated for day post-CBT with the HR representing the risk of day +100 death among those with ANC ≤ 100/μl relative to those with ANC >100/μl for each day. Results: Of the 137 patients who received a CBT on a research protocol, 99 patients (72%) received MA conditioning regimens and 38 patients (28%) received reduced-intensity conditioning regimens (RIC). Twenty-two patients (16%) received a single cord blood unit while the remainder received dCBT. As the overall results and trends observed for patients receiving MA or RIC regimens were similar, only the combined results are presented. Thirty-one patients (23%) died before day +100. Causes of death were primary graft failure (17), infection (7), disease relapse (5), multi-organ failure (1), and leukoencephalopathy (1). The median time to engraftment was the same (20 days) for those with death before day+100 (9–39 days) as those alive at day+100 (6–69 days). The hazard ratio for day 100 mortality by day post-CBT was significantly higher for patients with ANC ≤ 100/μl beginning on day +16 and remained so through day +50, at which point the number of patients with ANC ≤ 100/μl was small and thus the calculations were no longer significant. The HRs for each day post-CBT from day 0 to day +50 are plotted in Figure 1 along with their 95% upper and lower confidence intervals. From the graphical plot of these HRs, one can identify date ranges (days 0–12, days 13–23, days 24–40, days 41–100) where the HRs are roughly equivalent with a clear increase in HR in the next date range. Modeling ANC ≤ 100/μl as a time-dependent covariate, we calculated HRs for each of these date ranges and found a significantly increased risk of day 100 mortality for days 12–23 (HR=2.96, p=0.01), days 24–40 (HR=5.53, p=0.0004), and days 41–100 (HR=14.59, p<0.0001) for patients with ANC ≤ 100/μl. The HR was 1.16 (0.49–2.76, p=0.73) for days 0–12; however, some of these patients had initial autologous recovery following RIC regimens and poor outcomes. Conclusions: Our study demonstrates that severe neutropenia, defined as ANC ≤ 100, poses a significant increased risk of day 100 mortality for recipients of CBT as early as 12–23 days post-CBT. Importantly, this patient cohort was transplanted in the modern era of aggressive supportive care, including use of newer antimicrobials. However, despite this, severe neutropenia remains a significant risk factor for day 100 mortality in recipients of CBT. Interestingly, median time to engraftment (ANC ≥ 500/μl) was the same for those with death before day+100 as those alive at day+100 suggesting that time to ANC of 100 may be a better predictor of early death following CBT. Thus, strategies that result in more rapid myeloid recovery (to an ANC of 100) remain essential for recipients of CBT. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Influence of Infused Naïve CD3+CD8+ and CD3+CD56+ NKT-Cells on Single Unit Dominance After Double Cord Blood Transplantation

Abstract 652 Introduction:Double cord blood transplantation (dCBT) has emerged as a feasible alternative for the treatment of adults and children with hematologic malignancies. In the great majority of cases after dCBT, one unit emerges as the sole source of long-term hematopoiesis. However, the determinants and mechanism of this single unit dominance remain poorly understood. To investigate this dominance phenomenon we have analyzed the cell subset content of the cord blood (CB) units after dCBT. Methods: All CB units were thawed and washed by centrifugation prior to infusion, and a small sample removed from the final products post-wash for multicolor flow cytometric assessment of graft composition; viable cell subsets included stem/progenitors (CD34+), monocytes (CD14+), B (CD20+), NK (CD3−CD56+), NK/T (CD3+CD56+), and T-cell subsets (CD3+CD4+, CD3+CD8+, Memory, Naïve, Regulatory) expressed as infused cell subset/kg of actual recipient weight (in some cases insufficient sample was available for complete cell subset analysis on both CB units (see Table 1). Analysis of donor chimerism was performed on sorted peripheral blood CD3+, CD56+, CD14+ or CD33+ fractions on days 7, 14, 21, 28, 56, and 80 after transplantation. Single donor dominance was defined as more than 95% in all cell fractions. In the rare cases of both units engrafting, the unit contributing >60% hematopoiesis was considered the dominant one. A one-sample test of the null hypothesis that a binomial proportion is equal to 0.5 was used to test the association of concordance of higher cell dose with unit dominance. A one-sample paired t-test was also used to compare the mean differences in cell dose between winning and losing units. A total of 72 patients received dCBT between January 2008 and May 2011. Twelve patients (16%) were excluded because of death before informative chimerism data or due to graft failure. Sixty patients were included in the final analysis: 32 (54%) were conditioned with cyclophosphamide (CY) 60 mg/kg, fludarabine (FLU) 75 mg/m2 and total body irradiation (TBI) 1200–1320 cGy; 17 (28%) with Treosulfan 14 mg/m2, FLU 200 mg/m2 and TBI 200 cGy; and 11 (18%) with CY 50 mg/kg, FLU 200 mg/m2 and TBI 200 cGy. GVHD prophylaxis consisted of cyclosporine and mycophenolate mofetil. Results: Single unit dominance was observed in all recipients of myeloablative conditioning within 21 days of dCBT. Recipients of non-ablative conditioning initially had mixed donors-host chimerism but usually were 100% single donor by day 100. Similar to the findings of others, the unit containing the greater CD3 dose was statistically concordant as the dominant unit (p<0.0001). Of interest, further T-cell subset analyses showed dominance was more correlated with higher CD3+CD8+ (p<0.0001) than with CD3+CD4+ (p=0.001), and more with naive CD3+CD8+ (p=0.009) as compared with naive CD3+CD4+ (p=0.10). The CD3+CD56+ NKT cell content also showed a significant concordance (p=0.02). Furthermore, the mean difference in both naive CD8+ and NKT between what became the dominant and the non-dominant unit was 0.41 × 105/Kg and 0.11 × 104/Kg, respectively (p=0.008 and p=0.02). In contrast to other published reports, no significant associations were found with the infused dose of total cells or CD34+ cells, and no correlations with the infused dose of monocytes, B-cells, NK, memory CD3+CD4+ or CD3+CD8+, or regulatory T-cells were seen (Table1). Conclusion: These data indicate that higher T-cell content, in particular the naïve CD3+CD8+ T-cell subset, is crucial in determining which cord blood unit will ultimately predominate. Our findings provide further insight into the biology of dCBT, and support the hypothesis that dominance is an immune-mediated process in which naïve CD8+ T-cells and perhaps NKT cells within the graft play an important role. Our findings may have important implications for optimal unit selection, and for ex-vivo graft manipulations to enhance engraftment, immune reconstitution, and disease control. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Characterization of Chronic Graft-Versus-Host Disease and Duration of Immunosuppression After Cord Blood Transplantation,

Abstract 4077 Background:The reported incidence of chronic graft-versus-host disease (cGVHD) after cord blood transplant (CBT) varies widely in the literature, with some studies suggesting that cGVHD is more responsive to treatment after CBT than after conventional hematopoietic cell transplant (HCT). The 2005 National Institutes of Health (NIH) consensus criteria were designed to standardize the diagnosis and scoring of cGVHD. While these criteria have been used to evaluate GVHD after bone marrow (BMT) and mobilized blood (PBSCT) cell transplantation, analysis of GVHD after CBT by NIH criteria has been limited. We report the results of a single-center, prospective analysis of GVHD evaluated according to the NIH diagnostic criteria in adults and children receiving unrelated CBT after high or reduced-intensity conditioning. Methods:Eighty-seven consecutive patients who received a first single or double CBT between 2006 and 2011 were included. GVHD prophylaxis consisted of cyclosporine and mycophenolate mofetil. Grafts were HLA-typed at the antigen level for HLA-A and B, and high resolution for HLA-DRB1. Patients were prospectively evaluated for GVHD at day 80, 1-year, and at any other time as clinically indicated. Results:Median patient age was 31 years (range 0.8–70). Diagnosis at transplant included AML (n=49), ALL (n=20), CML (n=5), MDS/MPD (n=5), and other hematologic malignancy (n=8). The median follow-up after CBT was 24 months (range 1–127). Most patients received high-intensity conditioning (79%, n=69) and a double CB graft (86%, n=75). HLA-matching was 4/6 in 59% (n=51) of patients, 5/6 in 37% (n=32), and 6/6 in 4% (n=4). Median total infused cell doses were: 3.8 × 107 TNC/kg, 0.21 × 106 CD34+ cells/kg, and 10.9 × 106 CD3+ cells/kg. Neutrophil engraftment occurred in 90% of patients (n=78), at a median of 22 and 13 days after high and reduced-intensity conditioning, respectively. The cumulative incidence (CI) of grades II-IV and III-IV acute GVHD (aGVHD) was 74.7% and 29.9%, respectively. Sixty-eight patients (78%) were alive, engrafted with donor cells, and without relapse at day 80. Fifty-four patients had GVHD requiring systemic immunosuppressive treatment after day 80, for an estimated 2-year CI of 64%. Most patients had quiescent or interrupted onset (69%) and 48% had thrombocytopenia at time of diagnosis. By NIH criteria, 25 patients presented with “late” acute GVHD, and 29 presented with NIH cGVHD. Two patients who presented with “late” acute GVHD subsequently developed NIH cGVHD (Figure 1). Most patients with “late” acute GVHD had recurrent acute GVHD (n=20) with a median onset at 141 days after CBT (range 77–599). Organs affected by “late” acute GVHD were the GI tract (n=17), skin (n=12), and liver (n=5). Of the 31 patients with NIH cGVHD, 7 developed only the classic subtype with a median onset at 123 days after CBT (range 91–363). Organs affected in patients with classic NIH cGVHD were mouth (n=5), skin (n=5), lung (n=1), serosa (n=2), and genital (n=1). Most patients with NIH cGVHD had the overlap subtype (n=24), occurring at a median of 114 days after CBT (range 80–412). Organs involved in the overlap subtype included the GI tract (n=22), liver (n=7), acute skin (n=9), chronic skin (n=6), mouth (n=21), eyes (n=3), lung (n=1), esophagus (n=1), and serosa (n=3). The estimated 3-year CI of discontinuing immunosuppressive therapy (IST) while alive without relapse was 52%, while the 3-year estimated CI of death or relapse during IST was 33% (Figure 2). Among those who discontinued IST, the median time from onset of late acute GVHD or NIH cGVHD to discontinuation of IST was 12 months. In a previous study, the median time to discontinuation of IST for patients with cGVHD after BMT or PBSCT was 23 months. [Display omitted] [Display omitted] Conclusions:Despite a highly HLA-mismatched donor source, the CI of cGVHD after CBT is comparable to that after conventional HLA-matched unrelated donor HCT previously reported from our center. Our results indicate that GVHD occurring after day 80 post CBT frequently manifests itself as acute GVHD predominantly involving the GI tract. More importantly, these preliminary results suggest that time to resolution of GVHD diagnosed after day 80 appears to be shorter after CBT compared to after BMT or PBSCT. Disclosures:No relevant conflicts of interest to declare.

Infusion of “off-the-shelf” Third Party Ex Vivo Expanded Cord Blood Progenitor Cells As Supportive Care Following Clofarabine with High Dose Cytarabine and Granulocyte Colony-Stimulating Factor Priming for the Treatment of AML,

Abstract 3640Regardless of patient age, prolonged neutropenia and infectious complications are common side effects of AML induction and salvage chemotherapy, requiring intensive supportive care and contributing to treatment failure. Thus, novel therapies that can abrogate prolonged pancytopenia and facilitate more rapid hematopoietic recovery are needed. Previously, we have demonstrated that the absolute number of repopulating cord blood (CB) hematopoietic stem/progenitor cells (HSPC) can be increased by culture with Notch ligand; recent data from a Phase I double CB transplant trial utilizing ex vivo expanded CB HSPC has suggested more rapid neutrophil recovery (Delaney et al, Nat med). We hypothesize that this expanded cell product, which is devoid of T cells, could be cryopreserved and then infused as an off-the-shelf non-HLA matched product to provide rapid but temporary donor myeloid engraftment and might also facilitate autologous hematopoietic recovery following AML therapy, thus reducing the infectious complications associated with therapy.In a cohort of 50 patients, Becker et al at the Fred Hutchinson Cancer Research Center have reported on the use of clofarabine and high dose ara-c, in combination with G-CSF (GCLAC) in a phase I/II trial for the treatment of relapsed/refractory AML (Becker et al, Br. J. Haematol, in press). GCLAC is profoundly immunosuppressive and myelosuppressive, with periods of prolonged neutropenia post-GCLAC ranging from 17 to 35 days (median time to ANC >500 is 21 days) in this cohort. Infection was the most frequent adverse event, with ≥ grade 3 bacterial and fungal infections seen in 40% of patients (including 1st and ≥ 2nd salvage patients). We now herein report the preliminary results of a phase I safety trial investigating the use of GCLAC plus infusion of off-the-shelf expanded and cryopreserved CB HSPC for patients with AML.To date, 12 adult patients with relapsed (n=8), primary refractory (n=2) or de novo high risk (n=2) AML have been enrolled and received GCLAC as their first salvage or initial induction therapy. The median age and weight was 55 years (range, 38 to 59 years) and 79.5 kg (range, 63.8 to 126) respectively. Patients received cycle 1 of GCLAC followed by infusion of off-the-shelf expanded CB HSPC 24 hours after completion of chemotherapy. Patients who achieved a complete morphologic remission and did not experience any toxicities associated with the expanded cell product were eligible to receive a 2nd cycle of GCLAC with cells if not proceeding directly to stem cell transplant. A total of 15 products have been infused in 12 patients. Five of the 12 patients were refractory to GCLAC and therefore non-evaluable for neutrophil recovery. The median time to achieve an ANC > 500 in the evaluable patients was 19 days (range 18 to 27) after cycle 1, as compared to 21 days (range 17 to 35) in the historical cohort of patients receiving GCLAC only without expanded cells. Importantly, in this phase I study, there have been no infusional toxicities from the expanded cells or adverse events attributed to the expanded cell product. Alloimmunization has not been observed as monitored by pre- and post-infusion panel reactive antibody assays to determine the presence of donor directed antibodies.Four of the 12 enrolled patients have experienced clinically significant infections (e.g., bacteremia, fungal infections) compared to 40% in the comparison cohort, and no infectious deaths have been observed. Finally, in contrast to the first cycle of chemotherapy where donor cells were detected in only one patient, 4 out of 4 patients who received a 2nd cycle of GCLAC with expanded cells were found to have transient donor contribution to myeloid recovery (by peripheral blood cell sorted DNA chimerism assay) one week after infusion of the cells ranging from 85 to 100% donor in the CD33/CD14 cell lineages. Expanded cells were also able to home to the marrow as evidenced by transient donor engraftment (range, 3 to 15%) in recipient marrows one week after expanded cell infusion. It is unclear whether this is related to increased marrow “space” or increased host immunosuppression following cycle 2. With this encouraging data, we are continuing accrual of newly-diagnosed patients. This approach may decrease complications of pancytopenia and allow delivery of more dose-intense therapy, particularly in patients with intermediate/favorable cytogenetics who are already relatively sensitive to GCLAC. Disclosures:Delaney:Sanofi-Oncology (formerly Genzyme): Clofarabine for the study supplied by Sanofi-Oncology (formerly Genzyme). Becker:Sanofi-Oncology (formerly Genzyme): Research Funding.

Umbilical Cord Blood Hematopoietic Stem Cell Transplantation, an Alternative to Bone Marrow

Umbilical cord blood (UCB) is an alternative hematopoietic stem cell (HSC) source. It is widely applicable for ameliorating several diseases through HSC transplants. One of the few disadvantages of this source of stem cells is the limited amount of HSCs that can be extracted from each cord blood unit (CBU).Single CBU transplantation seems to be more ideal in lower weight, younger patients. Adult clinical studies comparing HSCs from a single CBU and HSCs from bone marrow indicate that umbilical cord blood transplantation is a viable method when a matched bone marrow transplant cannot be identified. Further clinical studies using two CBUs suggest better engraftment and lower risk of relapse. However, double cord blood transplantation has been faced with the challenge of single unit dominance in most studies. Ex vivo expansion of UCB HSC is another promising method to overcome limited HSC counts.

Stable Long-Term Pulmonary Function after Myeloablative Double Cord Blood Transplant

Pulmonary dysfunction has been well described after myeloablative transplantation with conventional allogeneic donors; however, whether the risk is similar after alternative donor transplantation with cord blood as the stem cell source has not yet been investigated. We performed a retrospective analysis of patients who underwent double cord blood transplantation after myeloablative conditioning. Pulmonary function tests were performed pretransplantation and at day 80, 1 year, and 2 years posttransplantation, with 56 patients included in the final analysis. No significant change from baseline with respect to the mean values and mean change in pulmonary function test values were observed at 1 year posttransplantation. The rate of lung function decline from baseline to 1 year posttransplantation was <5% in 75% patients; mildly abnormal lung function was reported in 58% of the patients. The cumulative incidence of noninfectious pulmonary complications was 9.7%. Future prospective studies are needed to confirm these findings.

Milestones in umbilical cord blood transplantation

Much has been learned about umbilical cord blood (UCB) since the first human cord blood transplant was performed back in 1988. Cord blood banks have been established worldwide for the collection, cryopreservation and distribution of UCB for allogeneic haematopoietic stem cell transplantation. UCB has now become one of the most commonly used sources of haematopoietic stem cells for allogeneic transplantation. Today, a global network of cord blood banks and transplant centres has been established with a large common inventory, allowing for more than 20000 transplants worldwide in children and adults with severe haematological diseases. Several studies have been published on UCB transplant, assessing risk factors such as cell dose and human leucocyte antigen mismatch. New strategies are ongoing to facilitate engraftment and reduce transplant-related mortality and include the use of reduced-intensity conditioning regimen, intra-bone injection of cord blood cells, double cord blood transplants or ex vivo expansion of cord blood cells. The absence of ethical concern and the unlimited supply of cells explain the increasing interest of using UCB for developing regenerative medicine.

Double Cord Blood Transplantation: Co-Operation or Competition?

Over the last two decades umbilical cord blood (UCB) transplantation (UCBT) is increasingly used for a variety of malignant and benign hematological and other diseases. The main factor that limits the use of UCB to low weight recipients, mainly children and adolescents, is its low progenitor cell content. Various alternatives have been exploited to overcome this difficulty, including the transplantation of two UCB units (double umbilical cord blood transplantation, dUCBT). Following dUCBT, donor(s) hematopoietic stem cells (HSC) can be detected in the peripheral blood of the recipient as soon as 14 days post-transplantation. Sustained engraftment of HSC from one or both donors can be observed- dominance or mixed chimerism respectively, although single donor unit dominance has been observed in over 85% of patients. The underlying biology, which accounts for the interactions both between the two infused UCB units- cooperative or competitive, and with the recipient’s immune system, has not been elucidated.

Outcomes, infections, and immune reconstitution after double cord blood transplantation in patients with high‐risk hematological diseases

Double unrelated cord blood transplant (dUCBT) has been used to circumvent cell dose limitation of single UCBT; however, few data are available describing outcomes, infectious disease, and immune recovery. We analyzed 35 consecutive dUCBT recipients with high-risk malignant disorders (n=21) and bone marrow failure syndromes (n=14). Median follow-up was 32 months. Conditioning regimen was myeloablative in 14 and reduced intensity in 21 patients. Median infused nucleated cell dose was 4 × 10(7) /kg. Median time to absolute neutrophil count >0.5 × 10(9) /L was 25 days. Cumulative incidence (CI) of acute grade II-IV graft-versus-host disease was 47%. Estimated overall survival at 2 years was 48%. CI of first viral infections at 1 year was 92%. We observed 49 viral infections in 30 patients, 34 bacterial infections in 19 patients, and 16 fungal or parasitic infections in 12 patients. Lymphocyte subset analyses were performed at 3, 6, 9, and >12 months after dUCBT. Decreased T-cell and B-cell counts with expansion of natural killer cells were observed until 9 months post transplantation. Recovery of thymopoiesis measured by T-cell receptor excision circles was impaired until 9 months after dUCBT, when the appearance of new thymic precursors was observed. Delayed immune recovery and high incidence of infectious complications were observed after dUCBT in patients with high-risk hematological diseases.

Adults requiring cord blood transplants but have insufficient cell doses from a single cord blood unit can receive two units with successful engraftment kinetics similar to those of children receiving a single unit

We retrospectively evaluated neutrophil engraftment kinetics in 29 single versus nine double unit cord blood transplants (CBTs). All single CBTs were performed in pediatric patients (non-malignant/malignant diseases, 19/10), while all double CBTs were performed in adults (n = 8) and an adolescent (n = 1) with hematological malignancies. Median follow-up time was 2.3 years (range, 0.1–13.5 years). Engraftment was achieved in 69% and 89% of the single and double cord blood (CB) groups, respectively. Similarly, median day of engraftment was not different for the single versus the double CBTs, at 19 and 23 days, respectively, and the neutrophil engraftment kinetics was similar in the two groups. Our data indicate that adults without sufficient nucleated cell doses in a single CB unit may receive two units with similar engraftment kinetics to those of children receiving only a single unit.

Donor Day 7 CD3 Chimerism Is Predictive of the Long-Term Engrafting Unit Following Myeloablative Double Cord Blood Transplantation (DCBT)

Donor Day 7 CD3 Chimerism Is Predictive of the Long-Term Engrafting Unit Following Myeloablative Double Cord Blood Transplantation (DCBT)

Stable Pulmonary Function Observed Over Time in Recipients of Myeloablative Double Cord Blood Transplant: A Single Center Experience

Stable Pulmonary Function Observed Over Time in Recipients of Myeloablative Double Cord Blood Transplant: A Single Center Experience

Making the Case for Private Cord Blood Banking: Mission Accomplished!

In our recent review [1] we provided a rational and evidenced based argument for the role of private cord blood banking in the developing field of cord blood stem cell technology. We were delighted to see that our review stimulated Schmidt et al., [2] to write a reply to our ideas as it was our intention to stimulate academic debate in this important area. The key message in our review is that private cord blood banking provides cord blood units which have a potential use as a source of stem cells for allogeneic transplant within the family and that those same units also have potential in future regenerative medicine procedures. The current arguments against private cord blood banking, especially by the professional bodies, focus on the limited use of private cord blood units in autologous transplantation. We do not challenge the fact that autologous transplantation of privately stored cord blood units is rare, we simply want to ask such critics to look beyond autologous transplantation in the context of the potential clinical utility of privately stored cord blood units. Equally importantly, we do not support misleading marketing by private cord blood banks which is in fact a rarity in the modern, highly regulated industry. Schmidt et al., claim that bone marrow donation is a ‘safe procedure’ but compared to cord blood collection it carries more risk. Bone marrow donation can cause pain at the collection site and fatigue and pain on walking or sitting in 6–20% of donors. Major and even life threatening complications such as anaesthesia related events, mechanical injury to bone, the sacro-iliac joint and the sciatic nerve occur in 0.1–0.3% of bone marrow donors [3]. It is a little surprising that, in a debate at this level, Schmidt et al., state that there is a ‘significant delay in granulocyte and platelet engraftment after related CB transplantation’. This is basic knowledge to everyone working in the field of haemopoietic stem cell transplantation [4] and is managed by competent transplant teams and new approaches such as double cord transplantation. This limitation applies to all types of cord blood transplantation, regardless of their source, and has no specific relevance to the private cord blood banking debate. It is equally confusing that Schmidt et al., choose to challenge our citation of Gluckman et al., [5] to support our concepts on the desirability of cord blood from related sources. The clear conclusion of Gluckman et al., is ‘Cord blood is a feasible alternative source of hematopoietic stem cells for pediatric and some adult patients with major hematologic disorders, particularly if the donor and the recipient are related’. It seems inconsistent to challenge the point we were making when it is clearly and independently supported by Gluckman et al. Schmidt et al., go one to suggest that bone marrow transplantation is the ‘standard approach’ when donor and recipient are HLA-identical and suggest that double cord blood transplants are in some way inferior. This paragraph suggests a lack of understanding of the field in general as an identical HLA match between bone marrow donor and recipient is rare and double cord blood transplants are only P. Hollands (*) Senior Lecturer in Biomedical Science, University of Westminster, 115, New Cavendish Street, London, UK e-mail: hollanp@wmin.ac.uk

Outcomes After Double Unit Unrelated Cord Blood Transplantation (UCBT) Compared with Single UCBT In Adults with Acute Leukemia In Remission. An Eurocord and ALWP Collaboration Study

AbstractAbstract 910The Minnesota group has described that recipients of double unrelated cord blood transplantation (dUCBT) have a higher incidence of acute GVHD, lower relapse incidence (RI) but no difference in leukemia free survival (LFS) when compared to single unit UCBT (sUCBT) recipients. In order to confirm these results in a larger and more homogenous cohort of patients and to evaluate the effect of double UCBT in relapse and LFS, we have compared the outcomes after dUCBT (n=230) with sUCBT (n=377) in adult patients with acute myeloid or lymphoblastic leukemia in remission. There were some differences between the two groups: dUCBT recipients were heavier (median weight: 68kg vs 65kg, p<0.01), tended to be older (median age: 37 years vs 35 years, p=0.06), had lower frequency of poor cytogenetics (32% vs 36%, p=0.02), transplanted more recently (p<0.001), more frequently given RIC (53% vs 30%, p<0.001), and received less ATG/ALG (29% vs 70%, p<0.001) when compared to sUCBT recipients, respectively. No differences were observed in diagnosis (38% ALL and 62% AML), status of disease at transplant (CR1: 52%, CR2:40% and CR3:8%) and previous autograft (13%). As expected, dUCBT recipients received a graft containing a higher nucleated cell dose (median of 3.7×107/kg vs 2.6×107/kg; p<0.0001). Number of HLA disparities were not statistically different (5/6:32% and 4/6:58%) when compared to sUCB grafts. Two analyses for outcomes were performed: one in patients transplanted in CR1 and other in patients transplanted in CR2 or more. The differences between dUCBT and sUCBT remained the same in both analyses. Results: in patients transplanted in CR1, median follow-up was 17 months for dUCBT recipients (n=114) and 19 months for sUCBT recipients (n=203). Unadjusted univariate analysis showed that cumulative incidence (CI) of neutrophil recovery was 78% after dUCBT and 82% after sUCBT (p=0.11); acute GVHD was 45% and 27% (p<0.001), and chronic GVHD 21% and 27% (p=0.35), respectively. At 3 years, unadjusted CI of NRM and RI were 32% after dUCBT and 36% after sUCBT (p=0.89) and 15% and 25% (p=0.03), respectively. Estimated 3 years LFS was 53% after dUCBT and 39% after sUCBT (p=0.09). In multivariate analysis, adjusted for the differences between the 2 groups, dUCBT recipients have an increased risk of grade II-IV acute GVHD (HR 1.23, p=0.005) and decreased RI (HR:0.74, p=0.01) when compared to sUCBT recipients. In a multivariate analysis adjusted, neutrophil and platelets recovery, NRM and chronic GVHD were not statistically different after dUCBT or sUCBT. However, in a multivariate analysis, LFS was improved after dUCBT compared to sUCBT recipients (HR: 0.67, p=0.04).In patients transplanted in CR2 and CR3, median follow-up was 11 months for dUCBT recipients (n=116) and 22 mo for sUCBT recipients (n=174). Unadjusted univariate analysis showed that CI of neutrophil recovery was 85% after dUCBT and 83% after sUCBT (p=0.57); acute GVHD was 33% and 17% (p=0.003), and chronic GVHD 32% and 29% (p=0.64), respectively. At 3 years, unadjusted CI of NRM and RI were 34% after dUCBT and 36% after sUCBT (p=0.47) and 31% and 33% (p=0.68), respectively. Estimated 3 Y LFS was 35% after dUCBT and 31% after sUCBT (p=0.48). In multivariate analysis, adjusted for the differences between the 2 groups, outcomes after dUCBT recipients, namely neutrophil recovery, acute and chronic GVHD, NRM, RI and LFS were not statistically different between the two groups. In conclusion our study confirms the previous findings of higher incidence of acute GVHD, equivalent NRM and reduced relapse in adult recipients of dUCBT, mainly for those transplanted in CR1, showing a higher GVL effect with improved LFS. Outcomes after dUCBT in patients with CR2 and CR3 were not statistically different of sUCBT. Double UCBT has extended the use of UCBT for patients otherwise not eligible for single UCBT and importantly is associated with better outcomes in adults patients with AL transplanted in early phase of the disease. 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.

Incidence and Risk Factors for Secondary Autoimmune Diseases (AD) After Cord Blood Transplantation (CBT). Retrospective Analysis on Behalf of Eurocord and the EBMT Autoimmune Diseases Working Party.

AbstractAbstract 3460Autoimmune diseases (AD) have been reported after haematopoetic stem cell transplantation (HSCT) and most commonly autoimmune cytopenias (AIC) are observed. Proposed risk factors are unrelated donor HSCT and presence of chronic graft-versus-host disease (GVHD). Use of CB cells is increasing as an alternative source of adults HSC for allotransplant however incidence and risk factors of AD after CBT have not been described. Since CB lymphocytes are immature and most of the CBT are HLA mismatched, we hypothesize a high incidence and diversity of secondary AD and. Therefore, we conducted a retrospective study in order to describe incidence, nature and risk factors for secondary AD after CBT. We include CBT recipients reported to EUROCORD up to December 2008. All centres were asked to participate to the survey even if they did not observe any case of AD after CBT. For those with AD, detailed information on diagnosis, treatment and outcome were asked. Median follow-up was 44 months (3.2-217). 42 out of 651 patients (pts) from 35 centres had developed at least one secondary AD at a median of 198 days (27-4267) after CBT. The remaining 609 pts without secondary AD served as control group (nonAD). Characteristics of both groups are given in table 1. Cumulative incidence of secondary AD after CBT was 5±1% after 3 years and 6.5±1% after 10 years. Diagnosis of secondary AD were autoimmune haemolytic anemia (AIHA) in 16, autoimmune thrombopenia (ITP) in 9, EVANS syndrome in 6, autoimmune thyroiditis in 3, glomerulonephritis in 2, Graves disease, psoriasis, psoriasis arthritis, immune neutropenia, ulcerative colitis and vasculitis in 1 patient each. Three pts developed ITP followed by AIHA. Median time to develop a AIC was 180 days (27-4267) and non-hematological AD was 322 days (70-1117), respectively (p=0.13). At onset of AD, 3 pts had acute GvHD, 6 chronic GvHD and in 10 pts an infection. In multivariate analysis adjusted for differences between the two groups, the following factors were associated with higher incidence of secondary AD: 1) age<10 years (8.8% vs 3.6%, HR:2.5; p=0.01); 2) CBT after 2006 (8.5% vs 3.4%, HR:2.23; p=0.01) and 3) non-malignant haematological disorders (12.5% vs 4.2%, HR 2.5, p=0.008). There was a trend of higher incidence of AD after unrelated compared to related CBT (6.7% vs 1.6%, HR: 3.71, p=0.07). Number of HLA disparities, cell dose, single or double CBT or use of ATG were not associated with incidence of AD. At last assessment, 317 of overall 651 pts and 35 of 42 pts with secondary AD were alive, respectively. Of 32 pts with AIC, all received immunosuppression as first line therapy (systemic steroids associated or not to CsA, cyclophosphamide) and in 14 ptsrituximab was added. Of those 14 pts receiving anti-CD20, 8 had a complete remission (CR), 3 a partial remission (PR) and 3 did not respond (died due to haemorrhage or infection associated to AIC). Of the 18 remainders 9 had a CR, 5 a PR and 4 did not respond (1 died). Among 6 patients without CR to first line treatment with rituximab, 1 responded to a second line with rituximab, 2 were alive after a different treatment and 3 died. Twenty-five patients with AIC were alive at last follow-up. Of 10 patients with other AD (non AIC), 7 were treated with immunosuppressive treatment (systemic steroids, CsA, tacrolimus), 2 with replacement therapy (thyroid hormone) and 1 treatment was not given (Graves disease); of those 9 patients treated, 7 achieved a CR and 2 a PR. All pts with non-AIC were alive at last follow-up. In conclusion, AD occur in more than 6% of 651 pts after CBT. Most often AIC (n=32) was diagnosed and it is associated with morbidity and mortality (7 pts died of 32). Younger age at transplantation and CBT for non-malignant disease are important risk factors for secondary AD.Table 1:Characteristics of pts developing AD or not (nonAD)Pts characteristicsAD ptsnonAD ptsPfemale sex36%45%age at HSCT2.23 (0.2–43.24) years10.7 (0.11–66.5) years0.0001year of HSCT2006 (95–08)2006 (92–08)0.04Type of donorunrelated95%90%0.26Indication for HSCT (n)ALL10184AML2150MDS467AA552SCID651CML324NHL021Hemoglobinopathy015Histiocytosis214Metabolic diseases919others111GraftSingle cord85%77%0.25Double cord14%23%HLA compatibility5/6+6/668%48%0.02ConditioningRIC80%73%0.34TBI20%43%0.0004Serotherapy73%74%0.86Host CMV statuspositive45%58%0.11 Disclosures:No relevant conflicts of interest to declare.

Interactions Between Total Nucleated and CD34 Cell Dose and Their Impact on Outcomes After Single and Double Unrelated Cord Blood Transplantation for Patients with Hematological Malignancies. An Analysis on Behalf of Societe' Française De Greffe De Moelle Et Therapie Cellulaire (SFGM-TC) and Eurocord

AbstractAbstract 361Pre-freezing (pf) and post-thawing (pt) total nucleated cells (TNC) is one of the most important factor for outcomes after UCBT. Its impact has been demonstrated after single UCBT (sUCBT); a minimum cell dose has been established as pfTNC of 2.5 ×107/kg, but its impact on outcomes after double UCBT (dUCBT) has not been shown. Also number of pfCD34 cells/kg is associated with outcomes after sUCBT, but only small series of patients have been analyzed. In order to evaluate the interactions between pf and pt TNC and CD34 and their impact on outcomes, we have studied separately 600 patients with hematological malignancies receiving a first sUCBT and 397 a first dUCBT in France (Table1). Methods:for all prognostic analysis pf and pt TNC and CD34 were divided into 4 categories at 25th, 50th and 75th percentiles. Results:Single UCBT: there was a highly statistical significant correlation between pf and pt TNC and CD34 (p<0.001, respectively). Median time to ANC recovery was 26 days (6-84). Cumulative incidence (CI) of ANC recovery at day 60 was 83%. In univariate analysis, the best cutoff point (associated with greater ANC recovery) of pfTNC and pfCD34 were ≥3.6 ×107/kg and '1.6 ×105/kg and ptTNC and ptCD34 were ≥3.3 ×107/kg and ≥1.3 ×105/kg. In multivariate analysis pf or pt TNC or CD34 were independently associated with ANC recovery (pfTNC HR=1.4, p=0.005; pfCD34 HR=1.3, p=0.01; ptTNC HR=1.4, p=0.01, ptCD34 HR=1.4, p<0.0001). We have not found any association of number of HLA disparities and ANC recovery. When analyzing only adults, patients receiving <2.0 ×107/kg, CI of ANC recovery was only 70% compared to 81% for ≥2.0 ×107/kg (p=0.02). CI of aGVHD at day 100 was 36% and was not associated with TNC or CD34. Estimated 2 year (y) OS was 47%, 2 y DFS was 40%. Interestingly, in a multivariate analysis, pfTNC, pfCD34 or ptCD34 were not associated with OS or DFS, but only higher ptTNC (≥3.3 ×107/kg) was associated with OS (51%vs43%, HR: 0.78, p=0.05) but not with DFS. Double UCBT: there was a highly correlation between pf and pt TNC and CD34 (p<0.001, respectively). CI of ANC recovery at day 60 was 81% in a median time of 23 days (5-64). In univariate analysis, pfTNC, pfCD34 and ptTNC were not associated with ANC recovery. However, there was an association of ptCD34 cell dose (Figure1) and ANC recovery. Chimerism data was available for 75% of the patients (n=298) during the first 100 days: 76% were full donor, 14% were mixed and 11% of the patients had autologous recovery. Autologous recovery was also associated with lower CD34 cell dose, it was 49% in patients receiving (<0.9×105/kg), and 25% for remainders (p<0.001). In multivariate analysis, ptCD34 >0.9x ×105/kg was the only independent factor associated with ANC recovery (HR=1.6, p=0.001). CI of acute GVHD at day 100 was 42% and was not associated with TNC or CD34 cell dose. At 1 y NRM was 22% and relapse incidence 26%. Estimate 1 y DFS was 50±3%. TNC or CD34 cell dose were not associated with any of the above outcomes. Only disease status at transplant impacts outcomes (64% early phase, 49% intermediate phase and 37% for more advanced disease). In conclusion, our study confirms the impact of cell dose measured by pf and ptTNC and CD34 on neutrophil recovery after sUCBT and the minimum cell dose recommended should be pfTNC≥2.5 ×107/kg and ptTNC≥2×107/kg, however only ptTNC is associated with survival in sUCBT. This is the first time that an impact of ptCD34 cell dose on neutrophil recovery after dUCBT is demonstrated and may be used to choose the best CB units. The different associations of cell dose in sUCBT and dUCBT can be explained by biological and immunological properties of other CB cells in the graft. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Use of Genome-Wide Expression Analysis to Optimize An Ex Vivo clinical Protocol for 16,16-Dimethyl Prostaglandin E2 Enhancement of Umbilical Cord Blood In Hematopoietic Stem Cell Transplantation.

AbstractAbstract 1451A systematic investigation was performed to optimize the treatment protocol for ex vivo incubation of human hematopoietic stem cells (HSCs) with 16,16-dimethyl prostaglandin E2 (FT1050) prior to transplantation. This protocol is part of an ongoing Phase Ib clinical trial of FT1050-enhanced double cord blood (CB) transplantation after reduced intensity conditioning. FT1050 has been previously shown in vertebrate models to improve the engraftment potential of HSCs from bone marrow (BM) and CB after a brief ex vivo treatment. In these models, treatment of BM or CB with FT1050 was performed for 1 to 2 hours at 4 °C, followed by a wash and subsequent cell infusion into the recipient (North et al. Nature 2007, Hoggatt et al. Blood 2009). Several groups have demonstrated that under these conditions, FT1050-treated cells have an engraftment advantage over vehicle treated cells. The objective of the current investigation was to identify a set of conditions that maximizes the biologic activity of FT1050. Genome-wide expression analysis and cAMP assays were used to optimize the ex vivo FT1050 treatment protocol with respect to concentration, time and temperature. Using this approach, hundreds of up- and down-regulated genes were identified in FT1050-treated CD34+ cells. These signature genes include upregulation of CXCR4, a known mediator of HSC homing via SDF-1a, and CREB, a key gene involved in cAMP signaling. Results from these experiments demonstrated that FT1050 concentrations above 10 μM did not result in increased levels of biologic activity. In terms of duration of incubation, cAMP activity reached maximal levels within 30 minutes of exposure while a 2 hour treatment period was necessary to maximize the changes in gene expression. Finally, the biologic activity of FT1050 was highly sensitive to temperature, with treatment of cells at 37 °C yielding larger changes in cAMP production and gene expression as compared to incubation of cells at 25 °C and 4 °C. The biological effects of FT1050 on subsets of CD34+ cells isolated from CB were also determined. Interestingly, the stem/progenitor subsets of CD34+ cells (Lin-CD34+CD38-CD90+CD45RA-, Lin-CD34+CD38-CD90-CD45RA- and Lin-CD34+) had a greater response to FT1050 relative to the lineage positive cells. The different conditions were also evaluated using CFU-C and 7-AAD assays. No evidence of adverse effects were observed. Based upon these findings, the ongoing clinical trial incorporates the optimized FT1050 ex vivo treatment protocol (10 μM for 120 minutes at 37 °C). Disclosures:Desponts:Fate Therapeutics, Inc.: Employment, Equity Ownership. Robbins:Fate Therapeutics, Inc.: Employment, Equity Ownership. Le:Fate Therapeutics, Inc.: Employment, Equity Ownership. Thies:Fate Therapeutics, Inc.: Employment, Equity Ownership. Mendlein:Fate Therapeutics, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Grayson:Fate Therapeutics Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Multani:Fate Therapeutics, Inc.: Employment, Equity Ownership. Shoemaker:Fate Therapeutics: Employment, Equity Ownership.

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.

Impact of Minimal Residual Disease at Unrelated Cord Blood Transplantation In Children with Acute Lymphoblastic Leukemia In Remission: a Study on Behalf of Eurocord-EBMT and EBMT-PDWP

AbstractAbstract 532Intensive and risk-adapted chemotherapy protocols may cure more than 80% of children with acute lymphoblastic leukemia (ALL). The detection of a positive minimal residual disease (MRD) in childhood ALL, is an independent prognostic factor of poor outcomes after chemotherapy treatment and has been used recently as a tool for risk stratification in most ALL treatment protocols. Its value before allogeneic related or unrelated hematopoietic stem cell transplantation (HSCT) has been described in small series of patients and it has been associated with outcomes. With the aim to investigate the prognostic significance of MRD before unrelated cord blood transplantation (UCBT) for ALL, we retrospectively analyzed children reported to the Eurocord registry. From 2000 to 2009, 316 children and adolescents with ALL in remission underwent a first single UCBT after a myeloablative conditioning regimen in 38 EBMT centers. Among these patients, 170 had an assessment of MRD before UCBT and were considered in this analysis. Of those, 72 patients underwent UCBT in first complete remission (CR), 77 in CR2 and 21 in CR3. The MRD assay was based on PCR (71%) or multiparameter flow cytometric analysis (FC) (29%). A positive MRD was defined according to treatment protocols of the various participating centers. MRD test before UCBT was positive (MRD+) in 74 patients (44%) and negative (MRD-) in 96 (56%). MRD was positive in 32 out of 72 patients in CR1, 31 out of 77 patients in CR2 and 11 out of 21 patients in CR3. The median interval from the last MRD test to UCBT was 18 days (12-42 days). The median follow-up was 46 months (4-104 months) and the median age at UCBT was 6.5 years (0.6-17 years). The most common immunephenotype was B-cell precursor ALL (83%). Of 72 patients transplanted in CR1, 56% had poor risk cytogenetics (t4;11 or t9;22). For patients in CR2 and CR3, the median interval between remission to relapse was 22 months (3-130 months). All patients received a TBI-based (63%) or Busulfan-based (37%), myeloablative conditioning regimen. GVHD prophylaxis consisted of cyclosporin (CSA) ± steroids in 75%. Sixty percent of cord blood units had 0–1 HLA mismatches with recipients and 40% had 2–3 mismatches (antigen level for HLA-A and B, allelic level for DRB1). Median infused TNC cell dose was 4.8 ×107/kg (1.30-18×107/kg) and median CD34+ was 1.8× 105/kg (1-10×105/kg). Cumulative incidence (CI) of day-60 neutrophil recovery (>500 mm3) and grade II-IV acute GVHD were 85±3% and 26±4%, respectively. Fifty-eight patients developed acute GVHD (grade 2, n=39, grade 3, n=14, grade 4, n= 5). The overall incidence of cGVHD was 17% at 4 years. Twenty-four patients had chronic GVHD (limited involvement, n=15, extensive disease, n=9). Overall CI of non-relapse mortality (NRM), relapse incidence (RI) and probability of leukemia free survival (LFS) at 4 years were 22±3%, 30±3%, and 44±4, respectively. In a univariate analysis, CI of NRM, RI and LFS at 4 years were 26±5%, 39±6%, and 29±5% in children with MRD+ and 20±4%, 24±3% and 54±5% in children with MRD- (p=0.08, p=0.05, p=0.006) respectively. In a multivariate analysis adjusted, a positive MRD before UCBT was an independent factor statistically associated with higher RI and decreased LFS (RI, HR=2.15, p=0.01, LFS, HR=1.97, p=0.003) (Figure 1). Also patients transplanted in more advanced status of disease at UCBT had higher RI and decreased LFS (RI, HR=4.25, p=0.002, LFS, HR=3.7, p=<0.0001); in fact, 4 years LFS was 56±6% for patients in CR1, 44±5% for patients in CR2 and 14±7% for patients in CR3 (p=<0.0001). Eighty-one patients died, causes of death were infections or other transplantation related events (n= 47) and disease progression (n= 34). The assessment of MRD in childhood ALL, is a powerful tool for predicting post transplant outcomes after UCBT. Approaches that can decrease relapse incidence in children with a positive MRD, such as better disease control before UCBT, rapid withdrawal of immunossupression, cell based immunotherapy or use of double cord blood transplantation, should be further investigated in order to improve final outcomes.Estimated 4-year Leukemia free Survival according to MRD status before UCBT [(••• MRD negative) (— MRD positive)] [Display omitted] Disclosures:No relevant conflicts of interest to declare.