Double-unit Cord Blood Research Articles

Analysis of Cyclosporine-a (CSA) Levels Supports New Dosing Guidelines in Adult Double Unit Cord Blood Transplant (dCBT) Recipients to Optimize Immunosuppression Early Post-Transplant

Analysis of Cyclosporine-a (CSA) Levels Supports New Dosing Guidelines in Adult Double Unit Cord Blood Transplant (dCBT) Recipients to Optimize Immunosuppression Early Post-Transplant

Cord blood transplant for acute myeloid leukaemia.

Umbilical cord blood is a haematopoietic progenitor cell source for patients with acute myeloid leukaemia (AML), other haematological malignancies and metabolic diseases who can be cured by allogeneic haematopoietic cell transplantation, but who do not have a human leucocyte antigen compatible related or unrelated donor. Although the first cord blood transplants were done in children, there are currently more cord blood transplants performed in adults. In this review, we explore the history of umbilical cord blood transplantation, paediatric and adult outcome results, and novel trends to improve engraftment and reduce infection. Umbilical cord blood transplantation cures approximately 30-40% of adults and 60-70% of children with AML. Controversial issues, including the use of double versus single cord blood units for transplantation, optimal cord blood unit selection, infection prophylaxis, conditioning regimens and graft versus host disease prophylaxis, will be reviewed. Finally, comparison to other graft sources, cost, access to care, and the ideal graft source are discussed.

Optimizing the Outcomes of Allogeneic Hematopoietic Stem Cell (HSC) Transplantation for Hematological Malignancies: The Perfect Combination of Conditioning Regimen, Disease Stage and Type of HSC Donor

IntroductionAllogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative strategy for a majority of patients with high-risk hematological malignancies. Several studies have evaluated the impact of conditioning intensity on the long-term transplantation outcomes, mainly retrospective and derived from large registries or non-randomized trials. These studies showed that more intensive conditioning (MAC) regimens are associated with a reduced risk of relapse, but do not translate into improvement of survival due to increased non-relapse mortality (NRM). Reduced intensity/Non-myeloablative conditioning (RIC/NMA) through graft-versus-leukemia effect has been associated with lower NRM, but higher relapse rates leading to similar overall survival (OS) when compared to MAC. However, in daily clinical practice, these results are difficult to follow because of the combination of important impact of disease stage, the type of HSC donor and its HLA matching with the patient. In addition, the historical nature of the previous studies may lead to the observation of different results today as the experience in drugs toxicities management has changed over time.The objective of this study is to evaluate the impact of the conditioning regimen intensity taking into account the disease stage and the type of HSC donor with its HLA matching on transplantation outcomes in a large population of patients with high-risk hematological malignancies.Material and methodsA total of 542 patients who received allo-HSCT between January 2006 and December 2014 in our center were included, 321 (59%) were males, the median age at allo-HSCT was 49 years (range: 18-70). There was 256 (47%) acute leukemia (202 AML, 54 ALL), 61 (11%) MDS, 60 (11%) multiple myeloma, 46 (8%) NHL, 25 (5%) Hodgkin's disease, 23 (4%) myeloproliferative neoplasms, 21 (4%) CML, 12 (2%) CLL and the rest with other hematological diseases. All patients were classified as at high-risk according to either clinical, immunophenotypic, cytogenetic or molecular markers. Conditioning regimen was classified as recently published (Gyurkocza et al. Blood 2014), therefore 282 (52%) received MAC and 260 (48%) received RIC/NMA; at allo-HSCT 320 (59%) patients were in CR and 222 (41%) in less than CR. HSC donor was identical siblings (Sib) for 199 (37%) patients (100 BM, 99 PBSC), 10/10 HLA matched unrelated (MUD) for 159 (29%) (79 BM, 80 PBSC), 6/6 HLA matched double cord blood (CB) units for 12 (2%), 9/10 HLA mismatched unrelated (MMUD) for 114 (21%) (54 BM, 60 PBSC), and the rest of 58 (11%) were 5/6 or 4/6 MM double CB units. For sex mismatching, in 119 (22%), it was female donor to a male patient; 295 (54%) were ABO compatible, 105 (20%) had minor incompatibility and 142 (26%) major incompatibility.ResultsThe median follow-up for surviving patients was 29 months (range: 4-96). We conducted a cox multivariate model for OS including patient age, disease status at allo-HSCT, conditioning regimen, type of donor and HLA matching, in addition to ABO and sex mismatching, with stratification on the type of disease; this model showed a significant impact of disease status in favor of CR (HR=1.5, 95%CI: 1.2-2.0, p=0.001), conditioning regimen in favor of MAC (HR=0.68, 95% CI: 0.53-0.88, p=0.003) and type of donor in favor of Sib (HR=0.68, 95%CI: 0.5-0.9, p=0.01). Interestingly, we were able to find an optimal association between these 3 factors leading to significantly better results in terms of OS and NRM independently of the disease type. When in CR, patients receiving MAC from Sib or from MUD had significant better OS and NRM compared to the rest of patients with 5-years rates of 71% vs 36% (p<0.0001) and 15% vs 37% (p=0.001) respectively. If not in CR, only patients who received HSC from Sib either after RIC or MAC showed significantly better OS and NRM compared to the rest of patients with 5-years rates of 50% vs 26% (p=0.001) and 22% vs 45% (p=0.008) respectively (see Figure). Considering only MMUD, patients receiving CB with RIC had better OS and NRM rates compared to 9/10 MMUD (RIC or MAC) and to MAC CB (p=0.07).ConclusionWe provide in this large study, a practical daily clinical practice outcome preview after allo-HSCT, independently of the type of disease, for the combination of significant impacting factors namely disease status at allo-HSCT, conditioning regimen and type of HSC donor with a superiority for MAC when used in CR from Sib or MUD. [Display omitted] DisclosuresNicolini:Ariad Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Mixed Chimerism at Three Months after Allogeneic Hematopoietic Stem Cell Transplantation Is a Significant Predictor of Disease Relapse in High-Risk Acute Myeloid Leukemia Patients in First Complete Remission

Background:Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potential curative strategy for high-risk acute myeloid leukemia (AML) patients. However, the risk for disease recurrence following allo-HSCT remains significant and associated with poor outcomes. The ability to predict relapse before detectable morphologic recurrence may allow for preemptive interventions, such as immune modulation, donor lymphocyte infusion (DLI), or initiation of hypomethylating agents, to potentially augment graft-versus-leukemia effect. Post-transplantation peripheral blood chimerism analysis, represents a potential tool to predict disease recurrence, although a validated consensus on the use of this technique in the post-allo-HSCT follow-up has not been established yet and its precise role in this setting remains unclear. The aim of our study is to evaluate the impact of chimerism evaluation 3 months after allo-HSCT in AML patients who were in first complete remission (CR1) before transplantation and remained in clinical and morphological CR at day 90 post-transplantation, on overall survival (OS) and relapse incidence.Patients and methods:We evaluated 194 AML patients who received allo-HSCT at our center between January 2006 and December 2014 and for whom chimerism follow-up has been performed at 3 months. There were 103 (53%) males and 91 (47%) females with a median age of 43 years (range: 18-67). Patients were classified according to the European LeukemiaNet classification for cytogenetic and molecular biology markers (Dohner et al. Blood 2010), accordingly, 64% patients were unfavorable and 36% were in intermediate II risk group. At allo-HSCT, all patients were in CR1; 136 (70%) received a full intensity conditioning (MAC) and 58 (30%) received a reduced intensity conditioning (RIC). HSC donors were 72 (37%) HLA identical siblings (44 BM and 36 PBSC), 54 (28%) 10/10 HLA matched unrelated donors (35 BM and 19 PBSC), 33 (17%) 9/10 HLA mismatched unrelated donors (16 BM and 17 PBSC) and 35 (18%) double cord blood units (only 7 were 6/6 HLA matched). Chimerism analysis was performed on marrow and/or blood samples every month following allo-HSCT using polymerase chain reaction (PCR) based on informative polymorphic short tandem repeat, a mixed chimerism was defined by having 5% or more of recipient cells.Results:At day 90 after transplantation, all patients remained in clinical and cytological CR at time of chimerism evaluation, 155 (80%) had a full donor chimersim (FDC) and 39 (20%) had a mixed chimerism (MC) ranging from 65% to 95% of donor cells. Among patients with MC, 9 (23%) received increasing doses of DLI (5 of them reached FDC at 6 months), while 20 (51%) could not receive DLI (7 because transplanted from cord blood, and 13 because of the presence of GVHD), the rest of patients were left with a transient MC and regained FDC during follow-up.After a median follow-up of 34 months (range: 4-96) for the surviving patients, the median OS in patients with FDC was not reached with a 3 years probability of 62% (95% CI: 58-66), and for patients with MC, it was 18 months (12-24) with a 3 years probability of 32% (95% CI: 23-41), (p=0.01). Twenty-two patients in the MC group have progressed during the follow-up and 17 among them died from disease progression. The cumulative incidence of relapse at 3 years was 25% (95% CI: 21-29) for FDC patients and it was 70% (95% CI: 62-80) for MC patients, (p<0.001). The impact of mixed chimerism was still valid in multivariate analysis after including patient age, type of donor, HSC source and risk group, and was independent from the intensity of the conditioning regimen with a Hazard Ratio of 4.7, and a 95% CI: 2.6-8.4, p<0.001.Conclusion:We demonstrated that chimerism evaluation at day 90 after allo-HSCT is an independent predictor of disease relapse in patients who remain in CR at that time and significantly impacts on long term survival. The standardization of this evaluation may lead to the identification of patients with high-risk of relapse risk suggesting the need of early preemptive intervention. [Display omitted] DisclosuresNicolini:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Ariad Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Selecting Double Cord Blood Units for Adults with Hematological Malignancies: Impact of ABO, HLA and Cell Dose on Outcomes after Double Cord Blood Transplants a CBC-Cellular Therapy & Immunobiology Working Party, EBMT and Eurocord Study

Despite the increased inventory of "rich" and more diverse HLA cord blood units (CBUs), most adults are still transplanted with double unrelated CBUs. Many studies have described criteria for CBU selection for single UCBT (SUCBT) based on cell dose, low and high resolution (LR and HR) HLA typing, KIR and NIMA. However, the criteria based on these factors for selecting double CBUs are still not as well defined. Moreover, most of SUCBT are performed in children whereas double UCBT (DUCBT) are commonly used for adults, therefore CBUs selection criteria may be different between in these two settings.With the aim of studying the impact of CBUs, patient and transplantation-related factors in DUCBT, we conducted a retrospective registry-based study in a large series of adults transplanted with DUCBT in EBMT centers, for whom we had available data on cell dose and HLA for both CBUs. Overall, 934 adults met the eligibility criteria: 55% had acute leukemia, 21% lymphoid mature malignancies, 10% MDS and 14% MPD or multiple myeloma. Patients' median age at DUCBT was 47 years (y) and median weight was 71 kg. Median time from diagnosis to DUCBT was 17 months. Conditioning regimen was myeloablative (MAC) in 32% and antithymocyte globulin (ATG) was used in 24% of the cases. GvHD prophylaxis consisted mostly of cyclosporine+mycophenolate mofetil. Median number of TNC at collection and infusion were 4.9 x107/kg (n=934) and 3.6x107/kg (n=735), respectively. Median number of collected and infused CD34 cells were 1.9x105/kg (n=893) and 1.6 x105/kg (n=695), respectively. Number of HLA disparities was defined according to the CBU with the highest degree of mismatches with the recipient, based on LR typing for HLA-A and -B and HR typing for -DRB1. Overall, 1% of the patients received a 6/6, 26% a 5/6, 67% a 4/6 and 6% a 3/6 HLA-matched DUCBT. ABO match was also classified according to the CBU with the highest incompatibility with the recipient: 18% of the patients received two ABO compatible CBUs, 30% at least one CBU with minor ABO incompatibility and 52% received at least one CBU with a major ABO incompatibility.At day 60, estimated absolute neutrophil count (ANC>500) recovery was 87%. In multivariate analysis (MVA) greater ANC recovery was associated with TNC dose at collection≥ 4.9x107/kg (HR:0.66; p=0.002), as well as female recipient, negative CMV serology and other diagnosis than MDS. Impact of CD34 cell dose was observed in univariate analysis: probability of ANC recovery was 91% if ≥1.9x105/kg versus 84% for a lower dose (p<0.001). At day-100, the incidence of acute GvHD (aGvHD) grade II-IV was 42% and III-IV was 20%. In MVA, increased aGVHD (II-IV) was associated with absence of ATG, use of MAC and HLA-match ≥4/6 (HR: 1.51, p=0.007), whereas increased aGVHD (III-IV) was associated with recipient's age (>47y), advanced disease, HLA-match ≥4/6 (HR: 1.55; p=0.048) and ABO major incompatibility (HR:1.44; p=0.039). The 2y NRM was 35%. Factors associated with higher NRM were positive CMV serology, advanced disease, use of ATG, ABO incompatibility (HR:1.55; p=0.023) and HLA-match ≥4/6 (HR:1.39; p=0.046). Relapse incidence (RI) at 2y was 20% and none of the CBU related factors impacted on RI. Overall Survival (OS) at 2y was 47%. In MVA, positive CMV serology, diagnosis of MDS and use of ATG were associated with decreased OS. Number of HLA disparities and degree of ABO compatibility were also associated with survival: 2y OS was 45% for patients transplanted with at least one ≥4/6 HLA-matched CBU, and 54% for those transplanted with both 6/6 or at least one 5/6 HLA-matched CBU (HR:1.26; p=0.05). Interestingly, OS at 2y was 57% for patients transplanted with both ABO compatible CBUs, 47% for those transplanted with at least one CBU with ABO minor incompatibility and 39% for those transplanted with at least one major ABO incompatibility (HR:1.16; p=0.029). In MVA for DFS, positive CMV serology, advanced disease, use of ATG and ABO incompatibility (HR:1.46;p=0.004) were associated with decreased DFS.This analysis suggests that a dose at collection of TNC ≥ 4.9x107/kg and/or of CD34 ≥ 1.9x105/kg, as well as better ABO and HLA compatibility are important factors that should be included in the selection algorithm for CBUs in DUCBT. DisclosuresNo relevant conflicts of interest to declare.

A Prospective Study of Allogeneic Hematopoietic Stem Cell Transplantation in Relapsed/ Refractory Hodgkin Lymphoma

INTRODUCTION: Patients with Hodgkin Lymphoma (HL) relapsing post autologous transplant (ASCT) are not cured with standard chemotherapy. In addition, a subset of patients with relapsed or primary-refractory HL fare poorly with ASCT. Such patients may benefit from allogeneic transplantation (allo-HCT) with its graft-versus-lymphoma (GVL) effect. METHODS: We performed a phase II study of salvage therapy (ST) followed by allo-HCT in adult patients with relapsed/refractory (rel/ref) HL (NCT00574496, Fig. 1a). Conditioning was dictated by PET status after ST, with NMA flu/cy/TBI 200 cGy for patients in CR and RIC mel/flu for those with PR/SD. Patients in the intent-to-treat (ITT) cohort were enrolled prior to ST and proceeded to allo-HCT if in CR, PR, or SD after 1 line of ST. The primary endpoint was successful allo-HCT and PFS at 1 year after allo-HCT (estimated as a proportion as all patients had at least 1 year of followup). Landmark analysis (from end of ST) with Kaplan-Meier curves and log-rank test were used to compare OS and PFS in the ITT cohort. A second cohort of patients referred with CR, PR, or SD after ST received HCT on protocol, but was not included in the ITT analysis. No differences in OS or PFS after HCT were seen between ITT and non-ITT cohorts, and patients were combined for further analysis. OS and PFS from time of HCT were estimated using all HCT patients, and PFS was compared based on baseline covariates. Cumulative incidence of GVHD, relapse/POD and nonrelapse mortality (NRM) were estimated using competing risks methodology. P-values less than 0.05 were considered significant. RESULTS: From 6/2008 to 6/2014, 25 patients were consented, 15 on the ITT analysis and 10 on the post-ST arm (Table 1). All had relapse after ASCT, primary refractory or high-risk HL relapsed within 1 year of 1st-line therapy. Allografts (n = 18) were PBSC from matched or single-allele mismatched related (n = 8) or unrelated (n = 3) donor, or double unit cord blood grafts (n = 7). Eleven were in PET CR before HCT and 7 in PR. ITT analysis (n=15) : 5 patients had POD on ST and were ineligible for allo-HCT. Of the remaining 9, 1 withdrew during conditioning. 1-year and 3-year OS were 50% (95% CI 22.5, 100) and 16.7% (95% CI 2.8, 99.7), respectively, in patients with POD after ST, and 100% at both time points if no POD after ST (Fig 1b). At median 5.6 years of follow-up, 5 patients survive. The percent of patients successfully meeting the primary endpoint was 33% (95% CI 13, 61). Allo-HCT analysis (n=18): Cumulative incidence (CI) of grade 2-4 and 3-4 aGVHD at d+100 were 23.3% (95% CI 13.1, 55.3) and 11.1% (95% CI 1.70, 30.4), respectively. CI of cGVHD at 1 year and 3 years was 11.1% (95% CI 1.7, 30.7) and 35.6% (95% CI 13.2-59.0), respectively, and of mild severity in all but 1 patient. 3-year CI of relapse/POD was 34.3% (95% CI 13.2-56.7), and NRM 23.6% (95% CI 6.8, 46.1). Estimated 3-year PFS was 42.1% (95% CI 24.1, 73.6) and OS 70.3% (95% CI 51.5, 96.1) (Fig 1c). There was no significant association between PFS and disease stage or status (CR vs. PR). There was a trend toward poorer PFS in the 5 patients without prior ASCT (3 year PFS 20.0% vs. 50.8%, p = 0.088), 3 of whom had primary refractory HL. CONCLUSION: We demonstrate that allo-HCT provides long-term survival for a substantial portion of patients with rel/ref HL. Though limited by small sample size, the ITT analysis showed more than 1/3 of patients never attained sufficient disease control for allo-HCT, and have a dismal prognosis. Of note, none had received brentuximab or a checkpoint inhibitor, and the long-term impact of these agents in those patients remains to be seen. In patients undergoing allo-HCT with chemosensitive disease, proceeding to allo-HCT in PET PR vs. CR had no significant negative impact on PFS in this limited sample. The trend toward poor outcomes in patients who had not previously undergone ASCT likely reflects poor prognosis in patients with primary refractory disease. Factors informing prognosis after allo-HCT, and interventions to attenuate risk, remain an important area for further investigation. Disclosures Perales: BeTheMatch/ National Marrow Donor Program: Membership on an entity9s Board of Directors or advisory committees; Takeda: Honoraria; Astellas: Honoraria; Merck: Honoraria; Amgen: Honoraria. Giralt: TAKEDA: Consultancy, Honoraria, Research Funding; JAZZ: Consultancy, Honoraria, Research Funding, Speakers Bureau; AMGEN: Consultancy, Research Funding; SANOFI: Consultancy, Honoraria, Research Funding; CELGENE: Consultancy, Honoraria, Research Funding. Straus: Millenium Pharmaceuticals: Research Funding. Moskowitz: GSK: Research Funding; Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding.

Association between Nondominant Unit Total Nucleated Cell Dose and Engraftment in Myeloablative Double-Unit Cord Blood Transplantation

Sustained hematopoiesis after double-unit cord blood transplantation (dCBT) is mediated by 1 unit in nearly all patients. To investigate the associations between nondominant unit characteristics and neutrophil engraftment, we studied 129 consecutive myeloablative dCBT recipients. Ninety-five percent (95% confidence interval, 90 to 98) of patients engrafted. Detection of the nondominant unit 21 to 28 days after dCBT was not associated with improved neutrophil engraftment. In univariate analyses, nondominant unit characteristics (infused total nucleated cell [TNC] and viable CD3+ cell doses) were significantly associated with speed and success of neutrophil engraftment as were dominant unit characteristics (infused TNC; viable CD34+, viable CD3+, and viable CD3-56+16+ cell doses; and post-thaw CD34+ cell viability). In multivariate analysis, higher infused TNC dose of the nondominant unit was independently associated with improved neutrophil engraftment, even when this unit did not contribute to donor hematopoiesis. In further subgroup analysis, this association was only evident when the infused viable CD34+ cell dose of the dominant unit was low (<1.20 × 105/kg). These findings suggest nondominant units mediate a dose-dependent facilitation of engraftment in myeloablative dCBT and support continued investigation of dCBT biology and the clinical practice of dCBT in adults in whom low cell dose grafts are common.

Evaluation of Initial Telomere Length and Changes after Transplantation in Adult Double-Unit Cord Blood Transplant Recipients

Cord blood (CB) leukocytes have inherent telomere length (TL) variation, and CB hematopoietic stem cells (HSC) can maintain high telomerase levels preventing telomere attrition in vitro. We evaluated TL changes in 13 adult double-unit CB transplant (CBT) recipients. In the 26 units, we observed a marked variation in CB TL at thaw (median, 9.99 kilobases [kb]; range, 6.85 to 13.5). All 13 patients engrafted. Of 11 engrafting with 1 unit, there was no correlation between unit dominance and TL (mean dominant unit TL, 8.84 kb ± 1.76; mean nonengrafting unit TL, 10.3 kb ± 1.81; P = .77). Serial measurements of TL up to 1 year after CBT demonstrated an overall mean 3.04 kb ± .16 TL decrease with only 1 patient exhibiting telomere maintenance. In summary, initial TL does not predict CB unit dominance. Moreover, our analysis suggests neonatal hematopoiesis makes a transition to an HSC characterized by changes in average TL and potentially low telomerase asymmetric cell division in adult CBT recipients. Further investigation of alterations in telomere length and its clinical implications after transplantation of this observation are indicated.

Intensified Mycophenolate Mofetil Dosing and Higher Mycophenolic Acid Trough Levels Reduce Severe Acute Graft-versus-Host Disease after Double-Unit Cord Blood Transplantation

Although mycophenolate mofetil (MMF) has replaced corticosteroids as immunosuppression in cord blood transplantation (CBT), optimal MMF dosing has yet to be established. We intensified MMF dosing from every 12 to every 8 hours to augment graft-versus-host disease (GVHD) prophylaxis in double-unit cord blood transplantation (dCBT) and evaluated outcomes according to the total daily MMF dose/kg in 174 dCBT recipients (median age, 39 years; range, 1 to 71) who underwent transplantation for hematologic malignancies. Recipients of an MMF dose ≤ the median (36 mg/kg/day) had an increased day 100 grade III and IV acute GVHD (aGVHD) incidence compared with patients who received >36 mg/kg/day (24% versus 8%, P = .008). Recipients of ≤ the median dose who had highly HLA allele (1 to 3 of 6) mismatched dominant units had the highest day 100 grade III and IV aGVHD incidence of 37% (P = .009). This finding was confirmed in multivariate analysis (P = .053). In 83 patients evaluated for mycophenolic acid (MPA) troughs, those with a mean week 1 and 2 trough < .5 μg/mL had an increased day 100 grade III and IV aGVHD of 26% versus 9% (P = .063), and those who received a low total daily MMF dose and had a low mean week 1 and 2 MPA trough had a 40% incidence (P = .008). Higher MMF dosing or MPA troughs had no impact on engraftment after myeloablation. This analysis supports intensified MMF dosing in milligram per kilogram per day and MPA trough level monitoring early after transplantation in dCBT recipients.

Double-Unit Cord Blood (CB) Transplantation (DCBT) Combined with Haplo-Identical Peripheral Blood CD34+ Cells (HaploCD34+) Is Associated with Enhanced Neutrophil Recovery, Universal Haplo Rejection, and Frequent Pre-Engraftment Syndrome

Double-Unit Cord Blood (CB) Transplantation (DCBT) Combined with Haplo-Identical Peripheral Blood CD34+ Cells (HaploCD34+) Is Associated with Enhanced Neutrophil Recovery, Universal Haplo Rejection, and Frequent Pre-Engraftment Syndrome

High Disease-Free Survival (DFS) Supports Continued Investigation of Double-Unit Cord Blood Transplantation (DCBT) in Children with High-Risk Acute Leukemia Especially in the Setting of Single Units with Low Dose and/or a High Degree of HLA-Mismatch

High Disease-Free Survival (DFS) Supports Continued Investigation of Double-Unit Cord Blood Transplantation (DCBT) in Children with High-Risk Acute Leukemia Especially in the Setting of Single Units with Low Dose and/or a High Degree of HLA-Mismatch

The Cell Loss after Thawing in Cord Blood Units

Umbilical cord blood (CB) are increasingly used for allogeneic transplantation as an alternative source to bone marrow or peripheral stem cell for patients who lack a human leucocyte antigen (HLA)-matched donor. Cell dose is one of the main determinant factor for selection of the unit and it has been shown to correlate with time and probability of engraftment. Cell doses available for selection of the unit are the ones evaluated before cryopreservation. Processing of the graft either with cryopreservation and/or thawing inevitably lead to cell loss but the data showing to what extent is very limited although this has great importance especially for the units with critical cell counts. To evaluate the extent of the cell loss after thawing and the effect of preservation duration on cell loss and the viability, we retrospectively analyzed our single center experience in a cohort of patients receivingunrelated CBT.Sixty cord blood units used for unrelated CBT in fifty-eight patients in our Pediatric Stem Cell Transplantation Unit were included in the study. One of the patient was transplanted with double cord blood unit and one had recurrent CBT because of previous graft failure.Median number of declared TNC per kilogram of recipient body weight was 16x107/kg (range: 3,16-59,1). After thawing the median TNC dose decreased to 11,1x107/kg (range:1,5-34), with median cell viability at 80%. The median TNC recovery was found as 70%. Median CD 34+ cell count declared by the banks per kilogram body weight of recipient was 6,0x105/kg (range: 0,5-37). The CD 34 cell count of one of the units used in a patient having double cord blood infusion was not available. The CD34 cell count of the other complementary unit was 0,48x105/kg. Since the total cell counts received bu the recipient was given, the CD34 cell count of the patient having double CB infusion was not included in statistical analysis. The median postthawed CD 34 cell count was 3,4 x105/kg (range: 0-21)and median CD34 cell recovery was %58.The storage duration of the CB units in liquid nitrogen was available for 59 units and that was 52±30 months (range:3-130 months). Correlation analysis did not show any significant correlation between CB unit storage duration and viability (r=-0,2 p=0.07). Also any correlation between storage time and also TNC and CD34 cell recovery were not identified.Our study indicated that approximately 30% of cell loss is expectable in cord blood transplantation because of either cryopreservation or thawing. It should be kept in mind while assessing acceptibility of cord blood units with limited cell counts DisclosuresNo relevant conflicts of interest to declare.

Analysis of 129 Myeloablative Double-Unit Cord Blood Transplantation Recipients Demonstrates an Independent Association Between Non-Dominant Unit TNC Dose and Engraftment Suggesting a Facilitation Effect

▪Introduction: Double-unit cord blood (CB) transplantation (dCBT) has been investigated to augment engraftment in patients without an adequately dosed single CB unit. However, only one unit engrafts in the majority of patients and the role, if any, of the non-dominant unit is not established.Methods: To investigate whether the non-engrafting unit facilitates engraftment of the dominant unit, we studied 129 patients (median age 34 years, 76% > 16 years) who underwent myeloablative dCBT for hematological malignancies at our center in 10/2005-8/2013. Chimerism testing at 21 and 28 days after dCBT was used to identify dominant and non-dominant CB units which could be assigned even in cases of clinical graft failure based on bone marrow chimerism.Results: The cumulative incidence of neutrophil engraftment at day 45 was 95% (95%CI: 90-98) and occurred at a median of 24 days (range 12-43). The dominant CB unit was the only unit detected in the peripheral blood by day 28 in 111 patients (86%) whereas both the dominant and non-dominant units were detected in the remaining 18 patients [median non-dominant unit contribution to chimerism 20% (range 6-48)]. Recipients of units that had close unit-unit HLA- allele match (7-9/10 vs 1-6/10) were more likely to have both CB units detected at day 28 (27% vs 9%, respectively, p = 0.018). However, there was no engraftment advantage associated with persistence of the non-dominant unit 21-28 days post-dCBT with a median neutrophil recovery of 27 days (range 14-34) in those co-engrafting with both units vs 24 days (range 12-43) in those engrafting with a single unit. In univariate analyses, dominant unit infused total nucleated cell (TNC) dose, infused viable CD34+ cell dose, infused viable CD3+ cell dose, infused viable CD3-56+16+ cell dose, and percentage of viable CD34+ cells post-thaw (CD34+ cell viability) were all significantly associated with neutrophil engraftment. However, the TNC (Figure) and CD3+ cell doses of the non-dominant unit were also associated with neutrophil engraftment on univariate analysis [hazard ratio (HR) 1.35, p < 0.001 and HR 1.16, p < 0.001, respectively] whereas non-dominant unit CD34+ cell and CD3-56+16+ cell doses were not (HR 1.18, p = 0.107 and HR 1.06, p = 0.159, respectively). Neither donor-recipient HLA-match of dominant or non-dominant units, nor unit-unit HLA-match, were associated with time to neutrophil engraftment. Notably, on multivariate analysis, the dominant unit infused viable CD34+ cell dose, dominant unit CD34+ cell viability, and the non-dominant unit infused TNC dose were each independently associated with the speed and success of neutrophil engraftment (Table). To further assess potential effects of the non-dominant unit TNC dose, we evaluated the subset of patients in whom haematopoiesis by day 28 was purely derived from the dominant unit. Among these 111 patients, non-dominant unit TNC dose remained independently associated with engraftment in multivariate analysis (HR 1.21, p = 0.026). Finally, we hypothesized that the non-dominant unit TNC dose effect may be seen primarily in patients whose dominant units had a relatively low infused viable CD34+ dose. Indeed, analysis revealed the non-dominant unit TNC effect was only evident in the two-thirds of patients (n = 86) whose dominant unit infused viable CD34+ cell dose was low (< 1.20 x 105/kg, HR 1.37, p = 0.006). There was no association in patients whose dominant unit had a higher infused viable CD34+ cell dose (HR 1.03, p = 0.799).Conclusions: While infused viable CD34+ cell dose of the dominant unit is critical, the non-dominant unit TNC dose was also independently associated with neutrophil engraftment after dCBT. Therefore, despite their lack of engraftment, non-dominant units may facilitate engraftment of the dominant units in myeloablative dCBT recipients. These data suggest dCBT is associated with interactions that foster engraftment of the dominant unit. This finding supports continued investigation of dCBT, especially in adults who are more likely to receive units with low CD34+ cell doses. Furthermore, the mechanisms that underlie this observation warrant investigation.TableTable (n = 129 dCBT recipients)Multivariate AnalysisHR95% CIp valueDominant unit viable CD34+ cell x 105/kg (continuous)1.721.41-2.10< 0.001Dominant unit CD34+ cell viability (%)1.031.00-1.050.026Non-dominant unit TNC x 107/kg (continuous)1.191.01-1.400.035 [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Successful Salvage of High-Risk B-Cell Non-Hodgkin and Hodgkin Lymphoma with Double-Unit Cord Blood Transplantation Provides a Platform for Further Optimization

Introduction: Allogeneic transplantation using double-unit cord blood grafts (DCBT) is an alternative therapy for adult patients with high-risk lymphomas without a HLA-matched sibling or volunteer donor but the efficacy of DCBT in this setting is not established.Methods: We analyzed overall survival (OS) and progression-free survival (PFS) after 4-6/6 HLA-matched DCBT in adults with B-cell non-Hodgkin lymphoma (NHL) or Hodgkin lymphoma (HL) who were transplanted 2/2006-5/2013.Results: Patient characteristics by diagnosis are shown in the Table. Overall, the 47 patients (median age 46 years, range 20-70) had a median number of prior treatment regimens of 4 (range 1-13), 22/47 (47%) patients had had a prior autologous transplant, and the median pre-transplant HCT-CI score was 2 (range 0-6). Twenty-eight (60%) were in complete remission (CR). Conditioning was reduced intensity (RI) but functionally myeloablative in 16 patients (8 Cy/Flu/Thio/TBI400, 8 Mel/Flu) and 31 patients received non-myeloablative conditioning (NMA, Cy/Flu/TBI200). CB units had a median infused TNC dose x 107/kg of 2.7 (range 1.5-4.3) for the larger unit and 1.9 (range 0.9-3.4) for the smaller unit and a median donor-recipient HLA-allele match of 5/8 (range 1-7). The cumulative incidence of donor-derived engraftment was 98% (95%CI:77-99) with a median 22 day (range 13-37) and 10 day (range 7-46) neutrophil recovery after RI and NMA conditioning, respectively. Day 100 grade II-IV acute GVHD (20 grade II, 7 grade III, 1 grade IV) and 1-year chronic GVHD were 61% (95%CI:45-74) and 17% (95%CI:8-29), respectively. Day 180 transplant-related mortality (TRM) was 17% (95%CI:8-29). To date, 11 patients have progressive disease (median 3.4 months, range 2.8-58.0). The 3-year cumulative incidence of progression was 22% (95%CI:11-34). With a median 60 month (range 15-101) follow-up of survivors, the 3-year KM estimate of OS and PFS are 56% (95%CI:44-73) and 44% (95%CI:31-61), respectively (Figure). Of 23 patients who have died, 7 died of progressive disease whereas 16 died of transplant complications (2 organ failure, 10 GVHD, 2 infection, 1 encephalopathy of unknown cause, and 1 donor leukemia). Best PFS was observed in patients with follicular NHL (3-year PFS 62%) followed by HL (3-year PFS 47%) whereas those with diffuse large B-cell lymphoma, for example, did poorly (Table). There was no differences in 3-year PFS according to recipient age, HCT-CI, or number of prior regimens (each split above versus below the median), or receipt of a prior autologous transplant (all p = NS). Similarly, patients in CR pre-CBT (n = 28) had a 3-year PFS of 42% as compared to a 46% PFS in the non-CR patients (n = 19), p = 0.568. Four of 11 patients who relapsed survive to date (range 29-81 months) after treatment with chemotherapy (n = 3) or subsequent CB-derived mobilized peripheral blood stem cell (PBSC) transplant (n = 1).Conclusions: PFS after DCBT in patients with follicular NHL and HL is similar to that of adult donor allograft series and warrants further investigation. However, DCBT in other histologies is not as favorable. The high TRM rates may be influenced by the extent/intensities of prior therapy. Future clinical trials with DCBT should focus on strategies to reduce TRM, especially related to GVHD. Post-transplant maintenance to prevent disease progression could also be beneficial. Finally,chemotherapy to treat post-CBT relapse and CB-derived PBSC transplant are potential therapeutic options in selected patients.TableDiseaseType(N)Median(range) ageMedian(range)HCT-CIRemission statusMedian (range) prior regimens /N prior autoRegimenintensityPFSFollicular(n = 13)52 yrs (29-63) 1 (0-4)5 CR, 5 PR, 3 SD4 (2-8) / 3/13 (23%)3 MA 10 NMA3-yr: 62% (95%CI: 40-95)Diffuse large cell(n = 13)53 yrs (35-64) 2 (0-6)8 CR, 4 PR, 1 SD4 (1-7) / 3/13 (23%)4 MA 9 NMA3-yr: 23% (95%CI: 9-62)Mantle cell(n = 5)57 yrs (37-71)2 (1-6)5 CR3 (2-4) / 4/5 (80%)5 NMA2 disease-free at 29-70 monthsHodgkins(n = 15)35 yrs (20-50)3 (0-5)10 CR, 3 PR, 1 SD, 1 PD4 (2-13) / 12/15 (80%)8 MA 7 NMA3-yr: 47% (95%CI: 27-80)T-cellrich B-cell NHL (n = 1)38 yrs2PR7 / No auto1 MADied at 1.5 months [Display omitted] DisclosuresMoskowitz:Merck: Research Funding; Genentech: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding.

Double-Unit Cord Blood (CB) Transplantation (DCBT) Combined with Haplo-Identical CD34+ Selected Peripheral Blood Stem Cells (PBSC) Is Associated with Enhanced Neutrophil Recovery, Universal Haplo Rejection and Frequent Pre-Engraftment Syndrome

▪Introduction While DCBT provides high rates of sustained donor engraftment, delayed neutrophil recovery is frequent and associated with increased transplant-related mortality.Methods We are investigating the combined transplantation of a 4-6/6 double-unit CB allograft with CD34+ selected haplo-identical PBSC (haploCD34+) to speed myeloid recovery in patients (pts) with high-risk hematologic malignancies. This analysis evaluates sustained neutrophil recovery, engraftment patterns, and potential factors associated with haplo-rejection in 36 DCBT-haploCD34+ recipients.Results 36 DCB-haplo-CD34+ pts (median 48 years, range 16-69) were transplanted 9/2012-6/2014. Diagnoses included 28 acute leukemias (24 CR or aplasia, 4 not in CR) and 8 advanced lymphoid malignancies. 2 pts had had a prior allograft. Conditioning was myeloablative (2 high-dose TBI, 34 reduced intensity) with CSA/MMF and no ATG. CB units had a median infused TNC (x 107/kg) of 2.26 (larger unit) & 1.87 (smaller unit), & a median HLA-allele match of 5/8 (range 2-7/8). Haplo-identical donors (median 37 years, range 18-71) had a median HLA-match of 4/8 (range 4-6/8). The median infused haplo-CD34+ dose was 3.1 x 106/kg (range 1.1-7.5). The median infused haplo-CD3+ dose was 1.5 x 103/kg (range 0.3-8.0). One patient died early post-transplant (multiorgan failure). In 35 evaluable pts, engraftment patterns [groups (Gp) 1-4] based on count recovery & chimerism are shown (Table). Overall, 34/35 (97%) pts recovered neutrophils (median day 13, range 11-38) whereas one 2nd allograft pt with donor-specific HLA-Abs (DSA) to haplo & both units had both primary haplo-rejection and CB graft failure (GF, Gp 4). Additionally, one pt (Gp 4) with transient haplo-mediated neutrophil recovery had subsequent CB GF in the setting of low CD34+ dose in the dominant unit. Both GF pts were salvaged with single-unit CBT. In other pts, haplo-rejection was universal & was associated with dominant CB unit derived T-cell engraftment although rejection speed varied, low haplo dose may have contributed in 2 pts, and 3 of 4 pts overall with haplo-DSA had no haplo-engraftment.TableEngraftment Pattern(n = 35) Median (range)Haplo DoseCD34+ x 106/kg Median (range) 8 Allele HLA-match: Haplo-PatientHaplo-Dominant CBN with DSAto Haplo/ CBsMedian (range)Dominant CB CD34+ Dosex 105/kg1) CB engraftmentwith haplo bridge (norecurrent neutropenia)N = 18 (51%) Median ANC 12 days, (range 11-14)3.14 (2.86-5.62)Haplo-patient: 4/8 (4-6/8) Haplo-dom. CB: 4/8 (range 1-7/8)1 pt DSA to haplo 1 pt DSA to loser CB1.14 (0.37-5.66)2)CB engraftment with transient haplo (2nd nadir)N = 5 (14 %) Median ANC 14 days, (range 11-38)3.0 (2.56-7.46)Haplo-patient: 4/8 (all 4/8) Haplo-dom. CB: 2/8 (2-4/8)None0.46 (0.25-1.00)3) CB engraftmentwith no haploN = 10 (29%) Median ANC 26 days, (range 15-33)3.00 (1.05-5.29)Haplo-patient: 4/8 (4-5/8) Haplo-dom. CB 3/8 (1-4/8)2 pts DSA to haplo 1 pt DSA to loser CB0.85 (0.54-1.39)4) Graft failureN = 2 (6%) Pt 1: transient haplo/ no CB Pt 2: no haplo/ no CBPt 1: 5.06 Pt 2: 4.64Haplo-patient: Pt 1: 4/8. Pt 2: 5/8 Haplo-dom. CB: Pt 1: 4/8. Pt 2: 4/8Pt 2: DSA to haplo, dom. CB & losing CBPt 1: 0.22 Pt 2: 1.27Of 35 evaluable pts, 27/35 (77%) developed pre-engraftment syndrome (PES, fever >38.3°C not due to infection +/- rash, capillary leak) at a median 10 day onset (range 7-14). PES occurred in 11/18 (61%) Gp 1 pts with robust haplo myeloid bridge vs 16/17 (94%) Gp 2-4 pts with rapid haplo-rejection. Overall, 3/27 (11%) PES pts required ICU care although marked improvement was associated with corticosteroids.Conclusions: DCBT-haploCD34+ is feasible & neutrophil engraftment is enhanced. However, given the haplo-graft can be rapidly rejected, and sustained engraftment is not guaranteed, the quality & dose of the CB unit(s) in this platform is critical. Preliminary analysis suggests the haplo-graft dose & haplo-DSA may be relevant in haplo engraftment whereas there is a high degree of dominant CB unit-haplo HLA-mismatch and its role is unclear. Finally, PES may be more common with prompt haplo-rejection, may be clinically severe, and mandates early diagnosis and pulse corticosteroids. Analysis of serial cytokine samples to further investigate PES biology is ongoing. DisclosuresNo relevant conflicts of interest to declare.

Disease-Free Survival in Adult Patients with Acute Leukemia and Advanced CML Supports Use of Double-Unit Cord Blood Grafts As an Immediate Alternative to 8/8 HLA-Matched Unrelated Donors (URD)

Background: Double-unit cord blood transplantation (DCB-T) is a rapidly available alternative to unrelated donor transplantation (URD-T) for patients with high-risk acute leukemia or advanced CML. Retrospective analyses in adult DCB-T suggest that double-unit CB grafts may be associated with improved disease-free survival (DFS). However, the prioritization of URD-T vs DCB-T is controversial.Methods: We evaluated 175 consecutive adult allograft recipients (120 URD-T and 55 DCB-T) aged 16-60 years transplanted 10/2005-11/2012 for acute leukemia in morphologic remission or aplasia (113 AML/ biphenotypic, 50 ALL), or advanced CML (n = 12). URD grafts were 7-8/8 HLA-matched (74 8/8, 46 7/8). CB grafts were 4-6/6 donor-recipient HLA-matched (4 6/6, 51 5/6, 55 4/6). All patients received either high dose or reduced intensity myeloablative conditioning. The majority of URD-T recipients (n = 111, 93%) received T-cell depleted (TCD) grafts with rabbit ATG, whereas GVHD prophylaxis for DCB-T was calcineurin-inhibitor/mycophenolate mofetil.Results: The median ages of URD-T (43 years) and DCB-T (42 years) recipients were similar (p = 0.713). Distributions of gender, recipient CMV positivity, HCT-CI scores, time from diagnosis or relapse to transplant, diagnoses, disease risk, and percentage of patients with minimal residual disease pre-transplant were also similar. Neutrophil engraftment was slower in DCB-T (95%, median 24 days) than URD-T (100%, median 11 days) (p <0.001). While the incidence of grade II-IV acute GVHD at day 100 was lower in TCD URD-T recipients (15%) than in unmodified URD-T (56%) and DCB-T (55%), p = 0.002, the incidence of day 100 grade III-IV acute GVHD was similar in TCD URD-T, unmodified URD-T, and DCB-T recipients (p = 0.794). With a comparable survivor follow-up [URD-T median 51 months (range 15-99) vs DCB-T median 46 months (range 15-92)], transplant-related mortality was similar (3-year estimates: URD-T 25% vs DCB-T 24%, p = 0.838) whereas the relapse risk was decreased after DCB-T (3-year estimates: URD-T 23% vs DCB-T 9%, p = 0.008). Overall, the 3-year DFS after URD-T was 52% and 68% after DCB-T (p = 0.056). When split into 3 groups, the 3-year DFS was 59% in 8/8 URD-T, 40% in 7/8 URD-T, and 68% in DCB-T, p = 0.043 (Figure). Multivariate analysis was performed to determine risk factors for disease relapse or death in the 175 patients (Table). Female gender (HR 1.65, p = 0.029), diagnosis of ALL (HR 2.11, p = 0.002), and mismatched URD-T (HR 1.97, p = 0.027) were each significantly associated with treatment failure.Conclusions: DCB-T can achieve favorable DFS in adults with acute leukemia and CML with low relapse rates. In this series, multivariate analysis demonstrated that mismatched URD-T was independently associated with lower DFS. Our findings support use of DCB-T as an immediate alternative for high-risk acute leukemia and advanced CML in adult patients without a readily available 8/8 allele HLA-matched unrelated volunteer donor. This could have the additional benefit of speeding time to transplant in high-risk patients.TableVariableMultivariateHR (95% CI)P-valueMale FemaleReference 1.65 (1.05-2.59)0.029 Recipient CMV Negative Recipient CMV PositiveReference 1.34 (0.85-2.12)0.201HCT-CI score 0-2 HCT-CI score > 3Reference 1.56 (0.98-2.47)0.059AML/CML ALLReference 2.11 (1.30-3.41)0.002DCB-T 8/8 URD-T 7/8 URD-TReference 1.32 (0.72-2.41) 1.97 (1.08-3.60)- 0.365 0.027 [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Second Allogeneic Stem Cell Transplantation for Hematologic Malignancies Using Chemotherapy Only Cytoreduction with Clofarabine, Melphalan, and Thiotepa

Background:Allogeneic hematopoietic stem cell transplantation (alloHSCT) plays an important role in the treatment of patients with high-risk hematologic malignancies. However, relapse of disease remains the primary cause of mortality post HSCT. Treatment options for these patients remain limited, and outcomes after salvage attempts are often poor, due to both increased toxicity and high rates of relapse. We describe a chemotherapy-only cytoreductive regimen consisting of clofarabine (Clo), melphalan (Mel) and Thiotepa (Thio) for the treatment of patients undergoing a second or third HSCT (HSCT2 or HSCT3).Methods: Between November 2005 and December 2012, 19 patients with hematologic malignancies who had relapsed after prior alloHSCT received a HSCT2 (N=17) or HSCT3 (N=2) using this regimen. There were 12 males and 7 females aged 4.5-44 years (median 20.2 years). Diagnoses and stages at the time of HSCT2/3 included: ALL in second complete remission (CR2; N=4) or CR3 (N=8); AML in CR2 (N=2) or CR3 (N=4); and CML in 2nd chronic phase (N=1). Seven patients had extramedullary disease, including CNS (N=5), testicle (N=1), and bone (N=1). Time to relapse following prior HSCT was 0-6 months (N=6), 6-12 months (N=7), or >12 months (N=6). Median time between most recent and present HSCT was 15 months (range 8.5 – 225 months). Thirteen patients received allografts from the same donor used for prior alloHSCT, while 6 pts received allografts from different donors. Grafts comprised conventional/unmodified marrow (cBMT) (N=7), peripheral blood (cPBSCT) (N=6), double umbilical cord blood units (N=1), or T-cell depleted (TCD) PBSCT (N=5). Cytoreduction included Clo 20 (N=18) or 30 (N=1) mg/m2/dose x 5, Thio 10 mg/m2 x 1, and Mel 70 mg/m2/dose x 2. GvHD prophylaxis included tacrolimus + methotrexate or mycophenolate for the unmodified grafts, while recipients of TCD grafts received ATG only pre-transplant for rejection prophylaxis. TCD was achieved by CD34+ selection, with the addition of E-rosetting in one case. All patients received filgrastim from day +7 until neutrophil engraftment.Results: Neutrophil engraftment occurred in all patients at a median of 12 days (range 9-25). Platelet recovery occurred in 17 evaluable patients at a median of 22 days (range 14-98). Transplant related mortality was limited to 2 patients, one who died of veno-occlusive disease 27 days post-transplant and the other of EBV lymphoma 11 weeks post-transplant. Neither of these patients recovered their platelet counts. Regimen related toxicity included: grade 3-4 mucositis (N=5), grade 4 renal toxicity (N=2), grade 3-4 hypoxia (N=3). Fifteen patients developed grade 3-4 transaminitis beginning immediately following clofarabine administration, which completely resolved in 14/15 cases. Five patients, all recipients of unmodified grafts, developed grade 2-4 acute GvHD, two of whom developed chronic GvHD; one patient who received a cPBSCT developed de novo chronic GvHD.Seven patients relapsed at a median of 14.6 months (range: 3.5-25.3 months) post-HSCT2/3, and all died of their disease. Ten of 19 patients are alive and disease free with median follow-up of 50.1 months (range 22.8-90.4). Overall and disease-free survival probabilities were 51.5% and 52.6% respectively. There were no statistically significant difference in OS or DFS for the following factors: (1) patient age < or ≥ 21 years, (2) grafts from same or different donor, (3) myeloid vs. lymphoid disease, (4) CR2 vs. CR3 at HSCT, (5) TCD vs. unmodified grafts. Outcome was significantly superior for patients whose relapse occurred > 6 months from prior HSCT, with an OS of 75.2% compared with 0% (p<0.0001) in patients whose relapse was ≤ 6 months. Of the 6 patients who received HSCT2/3 for relapse within 6 months of their first HSCT, 4 died from relapse, and 2 died from transplant related mortality.Conclusions: This cytoreductive regimen has allowed secondary transplants in a cohort of high-risk patients with ALL and AML who relapsed following a prior transplant using various graft and donor options. Overall, the regimen is well tolerated and has yielded promising results, specifically in patients who relapse more than 6 months from their prior transplant. This salvage treatment merits further study and evaluation in collaborative group studies. DisclosuresOff Label Use: Clofarabine, melphalan, and thiotepa all off label for bone marrow transplant.. Boulad:Genzyme Sanofi: Trials partially funded by Genzyme Sanofi Other.

Quantitative Assessment of T Cell Repertoire Recovery after Double Unit Cord Blood Transplantation Demonstrates Early T Cell Diversity and Correlation Between CMV Reactivation and CD8 Clonal Domimance

Introduction: Double-unit cord blood transplantation (DCBT) is a viable therapy for adults with high-risk hematologic malignancies who lack an adult donor. However, lack of transfer of memory T cells in the graft is associated with an increased risk of viral infections. To study immune reconstitution, we recently described a novel method that combines 5′ rapid amplification of complementary DNA ends (RACE) PCR and deep sequencing to quantify T cell receptor (TCR) diversity after allogeneic hematopoietic stem cell transplant (van Heijst, Nat Med 2013). In that study, we showed that recipients of DCBT recover TCR diversity comparable to healthy donors by 12 months. We now report results of a prospective analysis of CD4+ and CD8+ T cell repertoire recovery in DCBT recipients and correlation with clinical outcomes.Methods: We prospectively collected samples from 33 DCBT recipients. The median age was 45 years (range 26-71), 18 (55%) were CMV seropositive, and the majority (n = 17, 52%) had non-European ancestry. Diagnoses included 20 (61%) acute leukemias and 13 (39%) lymphomas. Conditioning was myeloablative (n=1, 3%), reduced intensity (n=28, 85%), or non-myeloablative (n=4, 12%), and all patients received GVHD prophylaxis with cyclosporine-A and mycophenolate mofetil and no ATG. Patients received double-unit CB grafts (4-6/6 HLA-A,-B antigen, -DRB1 allele donor-recipient matched); this was supplemented with haploidentical CD34-selected PBSC in 18 patients. The 66 units had a median donor-recipient HLA-allele match of 6/8 (range 3-8). Infused total nucleated cell doses were 2.3 (1.7-3.3) and 1.9 (1.3-2.5) for the larger and smaller units, respectively. Samples were collected from the DCB grafts, recipient day+21 bone marrow, and peripheral blood at days +30, 60, 90, 120, 180 and 365 post-transplant. TCR-β sequences from each sample were amplified and sequenced using the Illumina/MiSeq sequencing platform after isolation of CD4+ and CD8+ T cells. TCR abundances were assessed at the level of clonotype and TCR diversity was calculated using inverse Simpson index.Results: Of the 33 patients, long-term samples were obtained in 25 patients, short-term samples (≤ day 100) in 6 patients who died early after DCBT, and no samples other than the graft for 2 patients. The remainder of the results focuses on 25 patients with complete samples. As previously shown, there is a 1-2-log increased diversity in CD4+ vs. CD8+ T cells (Figure). Furthermore, median CD4+ steady-state diversity is achieved early by day 60. In contrast, there is a higher rate of clonal dominance in CD8+ compared to CD4+ T cells (24/25 vs. 11/25, p=0.0001 by Fisher test). Several patterns of clonal dominance were observed, including two main patterns in CD8+ T cells. In 7/24 patients, clonal dominance is established by day 60 and persists throughout, whereas in 12/24 patients, clonal dominance fluctuates throughout follow-up. In CD4 +T cells, where less dominance is observed, a similar distribution is seen, though prolonged clonal dominance is rare. Interestingly, some of the dominant clones can be detected in the graft and are present in the day 21 marrow sample. Persistent clonal dominance in CD8+ T cells was seen 6/9 patients with CMV reactivation, whereas ongoing fluctuation was seen in 9/12 patients without CMV reactivation. In 2 patients with fluctuating clones who reactivated CMV, 1 had low level and the other a late viremia. In contrast, no link to a specific pattern was observed in patients with HHV6 viremia or acute GVHD. Finally, when we assessed similarity in clonal distribution between time points, there was more similarity in CD8+ than CD4+ T cells.Conclusions: This novel deep TCR repertoire sequencing provides a quantitative picture of T cell recovery after DCBT and supports the following: 1) separate analysis of CD4+ and CD8+ T cell populations is critical given different patterns of recovery in T cell subsets; 2) there is significant turnover in CD4+ clones but with overall limited dominance, whereas there is less turnover in CD8+ clones; 3) although the grafts contain predominantly naïve T cells, the clonal evolution of CD8+ T cells strongly suggests generation of virus-specific T cells that control viral infection; and 4) CMV appears to be an important driver of CD8+ T cell clonal expansion after CBT. Ongoing analyses are correlating immune recovery with cord blood unit dominance as well as the biology of GVHD and relapse. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Comparable 3-Year Disease-Free Survival Regardless of Anti-Thymocyte Globulin Inclusion in Pediatric Myeloablative Cord Blood Transplantation for Acute Lymphoblastic Leukemia

Background: Cord blood (CB) is routinely used as an alternative stem cell source for the treatment of children with acute leukemia and has been associated with high rates of disease-free survival (DFS). However, one controversial issue in pediatric CB transplantation is the role of anti-thymocyte globulin (ATG) as immunoprophylaxis. While inclusion of ATG in the conditioning may decrease the risk of graft-versus-host disease (GVHD), it could potentially abrogate graft-versus-leukemia effects and increase the risk of opportunistic infections. Thus, we compared outcomes in a uniform group of pediatric patients with acute lymphoblastic leukemia (ALL) who underwent myeloablative CB transplantation with or without ATG.Methods: Patients with ALL in morphologic remission (CR1 n=106, CR2 n=146, CR3 n=45) aged ≤ 20 years transplanted between 01/2007-12/2011 with high-dose total body irradiation-based conditioning and single or double unit CB grafts were eligible for analysis. CB units were 4-6/6 HLA-A,-B at the antigen-level, -DRB1 allele matched to the recipient and had CB unit with cryopreserved total nucleated cell dose of ≥ 2.5 x107/kg/unit. Cox regression models were built to evaluate potential differences in outcome in ATG versus non-ATG CB transplant recipients. The primary endpoint was 3-year DFS.Results: Of 297 patients, 92 received ATG and 205 did not. Age and disease status were similar in each group whereas ATG recipients were less likely to be CMV seropositive and more likely to receive single unit CB grafts. While neutrophil engraftment was similar in each group, the risk of day 100 grade II-IV acute GVHD [30% (95%CI: 21-40) versus 54% (95%CI: 47-61), p = 0.0002] and 3-year chronic GVHD [22% (95% CI: 14-31) versus 43% (95% CI: 36-50), p = 0.0008] were decreased in ATG recipients. However, day 100 grade III-IV aGVHD was comparable: 11% (95%CI: 5-18) in ATG versus 17% (95%CI: 12-23) in non-ATG recipients, p = 0.15]. The 3-year TRM was similar in both groups: 16% (95%CI: 10-25) in ATG versus 17% (95%CI: 13-23) in non-ATG recipients (p = 0.98). Relapse was also similar in ATG and non-ATG recipients: 17% (95%CI: 10-23) versus 27% (95%CI: 21-34, p = 0.12), respectively. In multivariate analysis, negative CMV serostatus was associated with reduced TRM risk [HR 0.55 (95%CI: 0.30-0.98), p = 0.004] whereas remission status CR2 or CR3 significantly increased relapse risk [HR 2.18 (95%CI: 1.22-3.89), p = 0.008], but inclusion of ATG had no effect on either outcome. With a median follow-up of survivors of 36 months (range 5-72), the 3-year DFS was 66% (95%CI: 56-76) and 55% (95%CI: 48-62) in ATG and non-ATG recipients, respectively (p = 0.23, Figure 1). The distribution of causes of death was similar in each group. In multivariate analysis, treatment failure risk was increased in patients transplanted in CR2 or CR3, but the inclusion of ATG had no effect (p = 0.24) (Table 1).Conclusion: Inclusion of ATG in pediatric myeloablative CB transplant for ALL is associated with a decreased risk of grade II-IV acute GVHD and chronic GVHD but not severe grade III-IV acute GVHD. There was no difference in 3-year DFS in each group and multivariate analysis revealed ATG inclusion had no impact upon treatment failure risk. These results indicate that optimization of both ATG and non-ATG conditioning platforms are needed in order to further improve CB transplantation survival in children with ALL. Unanswered questions include the impact of the formulation, dose and timing of ATG administration. These findings cannot be extrapolated for other diagnoses, reduced intensity conditioning, or adults.Table 1Hazard ratio(95% confidence interval)p-valueATG useConditioning without ATG Conditioning with ATG1.00 0.78 (0.52 – 1.18)0.24 Disease statusCR1 CR2, CR31.00 2.01 (1.31 – 3.08)0.001 [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Minimal Residual Disease Does Not Impact Risk of Relapse in Myeloablative Umbilical Cord Blood Transplant Recipients: Comparison with Matched and Mismatched Unrelated Transplants

Introduction: Several studies have suggested that umbilical cord blood transplantation (UCBT) is associated with a lower risk of relapse when compared to matched and mismatched unrelated donor transplants (URD). However, the impact of minimal residual disease (MRD) on risk of relapse has not been investigated in comparative studies. With the aim to compare relapse and other transplantation outcomes based on MRD status at time of transplant, we conducted a retrospective analysis comparing myeloablative UCBT to URD.Methods: Between January 2006 and December 2012, 566 patients underwent a first allogeneic hematopoietic cell transplantation for hematologic malignancies with either a cord blood (CB) or URD stem cell graft. The UCBT group (n=112) received either a single- or double-unit CB graft. In the URD group (n=447), patients were allele-level matched with the donor at HLA-A, -B, -C, -DQB1, and -DRB1 (MURD (10/10), n=332) or mismatched for a single allele (MMURD (9/10), n=115). All patients received a myeloablative conditioning regimen. Graft–versus–host disease prophylaxis (GVHD) consisted of a calcineurin inhibitor (cyclosporine or tacrolimus) and either methotrexate (MURD and MMURD) or mycophenolate mofetil (UCBT). Ten-color multiparameter flow cytometry (MFC) studies on bone marrow aspirates were performed before HCT to evaluate MRD. Any level of residual disease was considered MRD-positive. The cause-specific hazards of failure (for death and for relapse) were compared between the UCBT group and each of the MRD groups using Cox regression.Results Recipients of UCBT were younger than MMURD and MURD, more likely to be non-caucasian, and more likely to be CMV seropositive. The UCBT and MMURD groups had a higher proportion of patients with higher disease risk when compared to MURD. MRD-positive patients were 34 (30%), 122 (36%) and 44 (38%) for UCBT, MURD and MMURD, respectively. The hazard of relapse in the MMURD group was higher than that in the UCBT group after adjusting for age, disease severity, year of HSCT, and MRD (HR=2.27; 95% CI 1.10-4.67; p=.03). The adjusted relative hazard of relapse in the MURD compared to the UCBT group depended on age (p=.03, interaction test), with younger and older patients having an increased risk and all other patients having a similar risk (Figure 1). The adjusted relative hazard of overall mortality (OM) in the MMURD group compared to the UCBT group was suggestively different based on MRD status with a HR=1.96 (95% CI 0.94-4.08; p=0.07) in MRD-positive patients and HR=1.00 (95% CI 0.54-1.83; p=0.99) among MRD-negative patients. With respect to the MURD group as compared to the UCBT group, the adjusted relative hazard was dependent on both MRD status and age. These associations are shown in Figures 2a (MRD-positive) and 2b (MRD-negative), with an increased hazard in younger MRD-positive patients and perhaps decreased hazard among older MRD-negative patients. The hazard of relapse was higher among MRD-positive patients than that among MRD-negative patients, but only in the MMURD (adjusted HR=1.83; 95% CI 1.05-3.19; p=0.03) and MURD group (adjusted HR=1.83; 95% CI 1.22-2.74; p=0.003). In stark contrast, the risk of relapse was similar between MRD-positive and MRD-negative patients in the UCBT group (HR=0.96; 95% CI 0.44-2.07; p=.91).Conclusions: Contrary to what has been demonstrated previously in MURD and MMURD transplants, our results suggest that pre-transplant MRD is not associated with increased risk of relapse after myeloablative UCBT. The data also suggest that the risk of relapse was higher in MMURD and was dependent on age for MURD recipients when compared to UCBT. The observed lower risk of relapse and the lack of impact of pre-transplant MRD in UCBT recipients suggest that UCBT should be considered first in younger patients with hematologic malignancies at high risk of relapse who lack an HLA-matched sibling donor. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.