Sustained Donor Engraftment Research Articles

The curative efficacy of unrelated umbilical cord blood stem cells transplantation in intensified myeloablative conditioned patients with acute lymphoblastic leukemia

To retrospectively analyze the efficacy of unrelated umbilical cord blood transplantation (UCBT) with intensified myeloablative conditioning regimen in patients with acute lymphoblastic leukemia (ALL). From September 2006 to December 2013, a total of 110 consecutive patients with ALL had received UCBT, including 79 male and 31 female patients with a median age of 14(2-51) years, a median weight of 45(12-100)kg. Sixty-one cases were in the first complete remission (CR), 30, 6 and 13 patients in the second, the third CR and advanced stages respectively. The conditioning regimen consisted of total body irradiation, cyclophosphamide and cytarabine (TBI/Cy/Ara-C) in 61 patients, busulfan, cyclophosphamide and fludarabine (BU/Cy/Flu) in 39 patients and BU/Cy/Ara-C in 10 patients. All patients received a combination of cyclosporine (CsA) and mycophenolate mofetil (MMF) for the prophylaxis of graft-versus-host disease (GVHD). The median amount of total nuclear cells(TNC) and CD34(+) cells were 3.90(1.97-13.50)×10(7)/kg and 2.07(0.40-5.56)×10(5)/kg. The cumulative incidence of sustained donor engraftment was 94.5% (95% CI 94.5%-94.6%) at a median of 18 days after transplantation (range, 12-37 days). The cumulative incidence of platelet recovery at 180 days after transplantation was 82.1% (95% CI 81.8%-82.4%) with a median time to recovery of 40 (range, 15-153) days. Incidences of grade Ⅱ~Ⅳ and Ⅲ~Ⅳ acute GVHD were 21.8% and 10.9% respectively. The cumulative incidence of chronic GVHD was 17.9%. During a median follow up period of 26 (range 6-94) months, the disease free survival (DFS) and overall survival (OS) rates at 3 years were 54.5% and 58.8%, respectively. The transplantation-related mortality (TRM) at 180 days after transplantation was 22.7%. The cumulative incidence of 3-year relapse rate was 18.3% (95% CI 17.9%-18.6%). UCBT with intensified myeloablative conditioning regimen not only improves the donor engraftment, but also shortens the interval of neutrophil and platelet recovery. It is a safe and effective option for children and adult ALL patients lack of matched related donors.

Low-dose total-body irradiation and alemtuzumab-based reduced-intensity conditioning regimen results in durable engraftment and correction of clinical disease among children with chronic granulomatous disease.

HSCT with MAC is associated with durable donor engraftment for patients with CGD; however, MAC is limited by high rates of RRT. We used a novel RIC regimen with LD-TBI (200 cGy × two doses), fludarabine (30 mg/m(2) × three doses), and proximal alemtuzumab (0.5 mg/kg/dose × one dose) and unrelated donor grafts for consecutive patients with high-risk CGD who were not candidates for MAC at our institution. Among four children with CGD transplanted at our institution, three PBSC recipients are alive with sustained donor engraftment (median follow-up: two yr) and resolution of pre-HSCT active infections while one patient with bone marrow graft is alive after graft failure and autologous recovery. RIC may be a curative option for children with high-risk CGD.

Studying the Optimal Intravenous Busulfan Exposure in Pediatric Allogeneic Hematopoietic Cell Transplantation (alloHCT) to Improve Clinical Outcomes: A Multicenter Study

s / Biol Blood Marrow Transplant 21 (2015) S79eS107 S102 success using HLA-matched related donors; however, use of alternative donors has been associated with increased graft failure, graft versus host disease (GVHD), and transplantrelated mortality (TRM). HSCT using alternative donors with post-transplantation cyclophosphamide (PT/Cy) has been performed for hematologic malignancies with engraftment, GVHD, and TRM comparable to that seen with HLA-matched related donors. There are limited reports of HSCT in nonmalignant disorders using alternative donors and PT/Cy. Design: We transplanted 9 patients with non-malignant conditions (CGD1⁄43, DKC1⁄42, DBA1⁄41, HyperIgM1⁄41, XIAP1⁄41, IPEX1⁄41) using an alemtuzamab/fludarabine based reduced intensity conditioning (RIC). All patients received GVHD prophylaxis with PT/Cy, with the addition of mycophenolate mofetil and tacrolimus for HSCT with haploidentical donors and for alkylator-sensitive diagnoses (DKC). Six patients had 10/10 HLA-matched unrelated donors, and 3 had HLA-haploidentical related donors. Results: All 9 patients successfully engrafted by day 30. Ultimately, all patients have had sustained donor engraftment sufficient to eliminate manifestations of their underlying diseases. 6 of 9 patients are full donor chimeras off immunosuppression,1 patient is a stablemixed donor chimera (76% CD3+ T cells) off immunosuppression, 1 patient is a stable mixed donor chimera on a calcineurin inhibitor (CNI), and 1 patient had secondary graft failure but was ultimately retransplanted with myeloablative conditioning using the same donor, resulting in full donor chimerism and elimination of disease. One patient developed Grade 1 and one patient Grade 2 acute GVHD, both treated successfully with steroids and a CNI. Mild skin chronic GVHD developed in 1 patient, treated successfully with phototherapy. No serious infections occurred and there was no TRM. 1 patient developed veno-occlusive disease, treated successfully with defibrotide. Disease-free survival is 89% with a median follow-up of 14 months (6-30 months). The patient with secondary graft failure is now disease-free after myeloablative transplant, for an overall disease-free survival of 100% at a median of 14 months follow-up (6-60 months). Overall survival is 100%. Conclusion: We have observed successful engraftment sufficient to eliminate manifestations of disease, limited GVHD, and no TRM in 9 patients with nonmalignant disorders using alternative donors, RIC, and PT/Cy. RIC HSCT with PT/Cy shows promise for curing nonmalignant pediatric disorders, and potentially eliminates the need for CNI use after MUD BMT. Development of prospective clinical trials to confirm these observations is warranted.

Autologous Transplant/Gene Therapy for Adenosine Deaminase-Deficient Severe Combined Immune Deficiency

s / Biol Blood Marrow Transplant 21 (2015) S79eS107 S102 success using HLA-matched related donors; however, use of alternative donors has been associated with increased graft failure, graft versus host disease (GVHD), and transplantrelated mortality (TRM). HSCT using alternative donors with post-transplantation cyclophosphamide (PT/Cy) has been performed for hematologic malignancies with engraftment, GVHD, and TRM comparable to that seen with HLA-matched related donors. There are limited reports of HSCT in nonmalignant disorders using alternative donors and PT/Cy. Design: We transplanted 9 patients with non-malignant conditions (CGD1⁄43, DKC1⁄42, DBA1⁄41, HyperIgM1⁄41, XIAP1⁄41, IPEX1⁄41) using an alemtuzamab/fludarabine based reduced intensity conditioning (RIC). All patients received GVHD prophylaxis with PT/Cy, with the addition of mycophenolate mofetil and tacrolimus for HSCT with haploidentical donors and for alkylator-sensitive diagnoses (DKC). Six patients had 10/10 HLA-matched unrelated donors, and 3 had HLA-haploidentical related donors. Results: All 9 patients successfully engrafted by day 30. Ultimately, all patients have had sustained donor engraftment sufficient to eliminate manifestations of their underlying diseases. 6 of 9 patients are full donor chimeras off immunosuppression,1 patient is a stablemixed donor chimera (76% CD3+ T cells) off immunosuppression, 1 patient is a stable mixed donor chimera on a calcineurin inhibitor (CNI), and 1 patient had secondary graft failure but was ultimately retransplanted with myeloablative conditioning using the same donor, resulting in full donor chimerism and elimination of disease. One patient developed Grade 1 and one patient Grade 2 acute GVHD, both treated successfully with steroids and a CNI. Mild skin chronic GVHD developed in 1 patient, treated successfully with phototherapy. No serious infections occurred and there was no TRM. 1 patient developed veno-occlusive disease, treated successfully with defibrotide. Disease-free survival is 89% with a median follow-up of 14 months (6-30 months). The patient with secondary graft failure is now disease-free after myeloablative transplant, for an overall disease-free survival of 100% at a median of 14 months follow-up (6-60 months). Overall survival is 100%. Conclusion: We have observed successful engraftment sufficient to eliminate manifestations of disease, limited GVHD, and no TRM in 9 patients with nonmalignant disorders using alternative donors, RIC, and PT/Cy. RIC HSCT with PT/Cy shows promise for curing nonmalignant pediatric disorders, and potentially eliminates the need for CNI use after MUD BMT. Development of prospective clinical trials to confirm these observations is warranted.

Autoimmune Hemolysis & Immune Thrombocytopenic Purpura after Cord Blood Transplantation (CBT) May be Life-Threatening & Warrants Early Therapy with Rituximab

▪Introduction: Autoimmune hemolysis (AH) & immune thrombocytopenic purpura (ITP) are recognized complications of CBT. However, the incidence, severity, treatment response, & prognosis of these autoimmune cytopenias are not established.Methods: We evaluated AH/ITP after CBT in a landmark analysis of 152 patients who received double-unit grafts, had sustained donor engraftment, & were disease-free at 100 days post-transplant. This landmark was chosen as no patient has developed AH/ITP prior to day 100. CBT recipients (median 38 years, range 0.9-70) were transplanted for hematologic malignancies with myeloablative (MA) or non-myeloablative (NMA) conditioning and calcineurin-inhibitor (CNI)/mycophenolate mofetil immunosuppression.Results: With a median follow-up of survivors in this cohort of 50.6 months (range 7.6-105.4) post-CBT, 9 patients [median age 42 years (range 2-54), 5 MA & 4 NMA conditioning] have developed autoimmune cytopenias (7 AH, 1 ITP, 1 both). All AH patients were IgG Direct Antiglobulin Test (Coombs) positive and ITP diagnosis was made by standard criteria. The cumulative incidence of AH/ITP is 6% (95%CI:3-11) at 3-years after the day 100 landmark with a median onset of 8.6 months (range 5.8-24.5) post-CBT (Figure). Six patients presented with severe disease (Hb <6 gm/dl &/or plts <20) requiring immediate aggressive supportive care. The lowest counts (Hb 2.6-6.8 & plts 0-4) were observed a median of 1 day (range 0-94) after diagnosis. Six patients had grade II-IV acute GVHD (onset 17-175 days post-CBT, all prior to development of AH/ITP), and all 9 cases developed in the context of immunosuppression taper. No relationship was observed according to age, diagnosis (acute leukemia vs lymphoma), preparative regimen intensity (MA vs NMA), or recipient CMV serostatus. Treatment during the first week included IVIg/corticosteroids/rituximab in 3 patients or a variety of approaches (1 increased CNI dose, 2 IVIg only, 2 rituximab only, 1 corticosteroids/IVIg). Overall, all 9 patients received rituximab starting 2-18 days (4-6 doses) with initial treatment. Early rituximab at <7 days from diagnosis reduced time to complete response (CR, Hb >8 &/or plts >100): median 13 days (7-49 days) in 4 early rituximab patients vs 58 days (19-98 days) in 5 without early rituximab. Moreover, an initial IVIg/corticosteroids/rituximab combination was best (CR 7-13 days). Four patients flared after CR at 28-393 days & all patients achieved CR with further therapy. Three patients underwent splenectomy (2 with initial therapy & 1 with flare). Eight/9 AH/ITP patients are alive & disease-free (one patient died of GVHD in remission from AH). Seven/8 surviving patients are in CR from AH/ITP (median 30 months after AH/ITP diagnosis, range 9-102) & 1 has recurrent AH requiring therapy. Treatment was well tolerated although 4 patients required intermittent IVIg & 4 had transient neutropenia. Conclusions: AH/ITP occurs infrequently after CBT but is associated with sudden onset and may be life-threatening. The onset during immunosuppressant taper suggests the mechanism may be due to transient immune dysregulation at this time-point, and investigation of whether AH/ITP can be predicted from analysis of B-cell immune reconstitution is underway. IVIg/corticosteroid/rituximab combination is appropriate initial therapy in severe disease & our data suggests this is the most effective although the role of IVIg is unclear. Earlier treatment with Rituximab may reduce corticosteroid exposure & avoid early splenectomy. While the optimal treatment regimen is not established, our series suggests rituximab is essential to achieve & maintain CR & has an excellent safety profile. Finally, survival was high in AH/ITP patients with no deaths from this complication although this was likely contingent on aggressive supportive care in these patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Allogeneic Transplantation for Chronic Myelomonocytic Leukemia (CMML) Is Associated with High Disease-Free Survival Even in the Setting of High-Risk Disease

Background: CMML has a poor prognosis with a median overall survival of about 30 months and a 15-20% risk of transformation to acute myeloid leukemia. For high-risk patients the median survival is 9 months. The only curative therapy is allogeneic hematopoietic stem cell transplantation (allo-HSCT). While several prognostic models have been proposed in CMML, their predictive value in allograft recipients is not well established. We report the outcome of allo-HSCT in 28 patients (pts) with CMML, and the relationship between five CMML prognostic scoring systems and post-transplant disease-free survival (DFS).Methods: 28 pts with CMML underwent allo-HSCT at MSKCC between 1/2002 and 2/2014. Pt and transplant characteristics are summarized in Table 1. Of the 28 pts, 6 had progressed to CMML-2 and 7 to AML pre-transplant. Except for 3 pts, all received chemotherapy before cytoreduction to decrease disease burden and all patients had <20% blasts prior to conditioning. Five prognostic scoring systems were used to classify the patients into low and high risk: 2 MDS and 3 CMML-specific models. T-cell depleted pts (n = 16, 60%) received myeloablative conditioning (12 busulphan/ melphalan/ fludarabine/ rabbit ATG and 4 TBI-based) whereas 12 pts (40%) received unmodified grafts with varying conditioning intensity. The source of HSC was 23 PB, 2 BM, and 3 cord blood.Results All pts had sustained donor engraftment. The cumulative incidences of day 100 grade II-IV acute graft-versus-host disease (GVHD) and 1-year chronic GVHD were 18% (95%CI:3-32) and 17% (95%CI:1-33), respectively. The 1-year incidence of transplant-related mortality was 7% (95%CI:0-17) with the most common transplant-related cause of death being infection. Three pts relapsed for a 1-year incidence of 13% (95%CI:0-26). These patients died of their disease. With a median follow-up of survivors of 3.3 years (range 3 months-11.6 years), the 3-year Kaplan-Meier estimate of overall survival is 74% (95%CI: 51-88) and DFS is 71% (95%CI: 47-85). All pts classified as having high-risk disease had similar survival to low risk disease pts (Table 2).Conclusion: This preliminary data suggests that allo-HSCT can achieve a high DFS in pts with CMML, even in the setting of high-risk disease. Thus, allo-HSCT should potentially be considered in all patients with CMML including pts who have a dismal prognosis based on current prognostic scoring systems.Table 1Patient and transplant characteristicsCharacteristicsN=28Age , years (range)60 (12-69)GenderMale Female- 18 (64%) 10 (36%)BM Blasts at diagnosis (%)<5 5-9 10-19- 13 (46%) 7 (25%) 8 (29%)Diagnosis karyotype risk group per Spanish ScoreGood Intermediate/Poor- 17 (60%) 11 (40%)WHO classification at diagnosisCMML-1 ( <10 % BM blasts) CMML-2 (10-20% BM blasts)- 20 (71%) 8 (29%)FAB classification at diagnosisMyelodysplastic subtype (< 13000 WBC) Myeloproliferative subtype (> 13000 WBC)- 14 (50%) 14 (50%)WHO status at progression (highest disease)CMML -1 CMML -2 AML- 12 (43%) 9 (32%) 7 (25%)Pre-transplant therapyNo chemotherapy Hypomethylating agent AML type chemotherapy- 5 (18%) 10 (36%) 13 (46%)BM Blasts pre-transplant (%)<5 5-9 10-19- 21 (75%) 4 (14%) 3 (11%)Transplant conditioningMyeloablative Reduced intensity- 22 (78%) 6 (22%)Donor8/8 HLA Matched related donor 8/8 HLA Matched unrelated donors HLA-mismatched unrelated donors Cord blood- 13 (46%) 9 (32%) 3 (11%) 3 (11%)GVHD prophylaxisT cell depletion Calcineurin inhibitor- 16 (60%) 12 (40%)Table 2:DFS per risk level defined by different prognostic models *CMML- specific scoring systemsPrognostic ScoreN3 year DFSIPSS-R0-1 2-3- 11 17- 83% 63%MDASC0-1 2-3- 21 7- 71% 69%MDAPS *0-1 2-3- 16 12- 68% 74%Mayo * 0-1 2- 10 18- 56% 76%Spanish Score *0-1 2-3- 20 8- 68% 75% DisclosuresBoulad:Genzyme Sanofi: Trials partially funded by Genzyme Sanofi Other.

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.

Donor hematopoiesis in mice following total lymphoid irradiation requires host T-regulatory cells for durable engraftment

AbstractTotal lymphoid irradiation (TLI) with antithymocyte globulin (ATG) is a unique regimen that prepares recipients for allogeneic hematopoietic cell transplantation by targeting lymph nodes, while sparing large areas of the bone marrow. TLI is reported to increase the frequency of CD4+CD25+FoxP3+ T-regulatory cells (Treg) relative to conventional T cells. In this study, barriers to hematopoietic stem cell (HSC) engraftment following this nonmyeloablative conditioning were evaluated. TLI/ATG resulted in profound lymphoablation but endogenous host HSC remained. Initial donor HSC engraftment occurred only in radiation exposed marrow sites, but gradually distributed to bone marrow outside the radiation field. Sustained donor engraftment required host lymphoid cells insofar as lymphocyte deficient Rag2γc−/− recipients had unstable engraftment compared with wild-type. TLI/ATG treated wild-type recipients had increased proportions of Treg that were associated with increased HSC frequency and proliferation. In contrast, Rag2γc−/− recipients who lacked Treg did not. Adoptive transfer of Treg into Rag2γc−/− recipients resulted in increased cell cycling of endogenous HSC. Thus, we hypothesize that Treg influence donor engraftment post-TLI/ATG by increasing HSC cell cycling, thereby promoting the exit of host HSC from the marrow niche. Our study highlights the unique dynamics of donor hematopoiesis following TLI/ATG, and the effect of Treg on HSC activity.

Sustained Donor Engraftment in Recipients of Double-Unit Cord Blood Transplantation Is Possible Despite Donor-Specific Human Leukoctye Antigen Antibodies

The impact of human leukocyte antigen (HLA) donor-specific antibodies (DSA) on cord blood (CB) engraftment is controversial. We evaluated the influence of pre-existing HLA-antibodies (HLA-Abs) on engraftment in 82 double-unit CB recipients (median age, 48 years) who underwent transplantation for hematologic malignancies. Of 28 patients (34%) with HLA-Abs, 12 had DSA (median mean fluorescence intensity 5255; range, 1057 to 9453). DSA patients had acute leukemia (n = 11) or myelodysplasia (n = 1) and all received either high-dose or reduced-intensity (but myeloablative) conditioning. After myeloablative CB transplantation (CBT) (n = 67), sustained donor engraftment was observed in 95% without HLA-Abs (median, 23 days), 100% with nonspecific HLA-Abs (median, 23 days), and 92% with DSA (median, 31 days, P = .48). Of 6 patients with HLA-Abs to 1 unit, 3 engrafted with that unit and 3 with the other. Of 6 patients with HLA-Abs against both units, 1 had graft failure despite being 100% donor, and 5 engrafted with 1 unit. Successful donor engraftment is possible in patients with DSA after myeloablative double-unit CBT. Our data suggest potential deleterious effects of DSA can be abrogated in patients with hematologic malignancies.

“No Wash” Albumin-Dextran Dilution for Double-Unit Cord Blood Transplantation is Safe with High Rates of Sustained Donor Engraftment

Washing cord blood (CB) grafts involves product manipulation and may result in cell loss. We investigated double-unit CB transplantation (CBT) using red blood cell (RBC)–depleted units diluted with albumin-dextran in patients with hematologic malignancies. One-hundred thirty-six patients (median age, 43 years; range, 4 to 71; median weight, 69 kilograms (kg); range, 24 to 111) underwent transplantation with a 4/6 to 6/6 HLA-matched graft. Patients ≤ 20 kg were excluded, as they only received washed units. Units were diluted a median of 8 fold to a median volume of 200 mL/unit. The median infused total nucleated cell doses were 2.7 (larger unit) and 2.0 (smaller unit) x 107/kg, respectively, and the median post-thaw recovery was 86%. Units were infused consecutively (median, 45 minutes/unit). While only 17 patients (13%) had no infusion reactions, reactions in the remaining 119 patients were almost exclusively mild-moderate (by CTCAE v4 criteria 12 grade 1, 43 grade 2, 63 grade 3) with only 1 patient (< 1%) having a severe (grade 4) reaction. Moreover, most were easily treated. Grade 2 to 3 hypertension was the most common in 101 (74%) patients. The cumulative incidence of sustained donor-derived neutrophil engraftment was high: 95% in myeloablative and 94% in nonmyeloablative CBT recipients. With appropriate supportive care, double-unit CBT with RBC-depleted grafts infused after albumin-dextran dilution is safe with high rates of engraftment in patients > 20 kg.

Umbilical Cord Blood Transplant Patients At High Risk Of Graft Rejection Achieve Early Full Donor Chimerism When 300cGy Is Used In The Reduced Intensity Conditioning Regimen

BackgroundWhile delayed or failed engraftment following reduced intensity conditioning (RIC) umbilical cord blood transplant (UCBT) now occurs less frequently than initially reported, it continues to be higher than in the conventional donor setting. It has been shown that patients who have had a prior autologous transplant or who have received chemotherapy within 4 months of UCBT have an increased incidence of sustained donor engraftment compared with those without this prior therapy (98% vs 64%) (Barker et al ASH abstract 2003). The standard measure of engraftment following UCBT is neutrophil recovery to > 500 x 3 days. However, there has recently been established a possible correlation between time to neutrophil engraftment and early full donor chimerism after UCBT (Avery S et al BMT 2012). Herein, we conducted an RIC UCBT trial in which patients were assigned to one of two treatment regimens based on their risk of graft failure. In addition to evaluating sustained donor engraftment characterized by time to neutrophil recovery, we also sought to assess the achievement of full donor chimerism at Day +28 post-transplant in patients pre-determined to be high versus low risk of graft failure. MethodsForty-eight patients median age 59 years (range 25 - 73) and comorbidity index = 3 (range 0 - 8) with high risk hematologic malignancies received an RIC regimen containing cyclophosphamide 50mg/kg on Day -6, fludarabine 40mg/m2 Day -6 to -2 (dose reduced to 35mg/m2 for creatinine clearance < 70), and either 200 cGy TBI (Arm 1 = low risk of graft failure) or 300 cGy TBI (Arm 2 = high risk of graft failure) on Day -1. High risk for graft failure was defined as “receiving < 2 cycles of multiagent chemotherapy or no multiagent chemotherapy within the 3 months prior to UCBT.” Low risk for graft failure was defined as “having received a prior autologous transplant within 12 months or ≥ 2 cycles of multiagent chemotherapy with at least one cycle of therapy within the 3 months prior to UCBT.” Patients on both arms received GVHD prophylaxis with cyclosporine from Day -1 to Day +180 and mycopheolate mofeteil 1 gram every 8 hours until Day +40. Forty-seven of 48 patients received 2 UCB units (one patient received a single UCB) with a median TNC/kg of 4.05 x 107 and a post-thaw median CD34+cells/kg of 1.75 x 105. UCB grafts (98%) were 1-2 HLA antigen mismatched with the recipient. Twenty-six patients were assigned to Arm 1 and 22 patients were assigned to Arm 2. Bone marrow and peripheral blood chimerism assessment were performed at approximately Day +28 and Day +80. The blood was flow sorted in the clinical hematopathology lab into defined lineage subsets. Wilcoxon rank-sum test was used to compare the 2 groups. ResultsAll evaluable patients engrafted (n = 46). Patients on Arm 1 achieved neutrophil recovery (ANC > 500 x 3 days) at a median of 12 days (range 6 - 38) versus 23 days (range 7- 46) in patients on Arm 2 (p = 0.01). Day +28 chimerism values were evaluable for 23 patients on Arm 1 and 20 patients on Arm 2. Median chimerism in the CD3+ compartment was 100% (57 - 100) and 100% (0 - 100) on Arm 1 and Arm 2 respectively (p = 0.58). Median chimerism in the CD33+compartment was 98% (15 - 100) and 100% (44-100) on Arm 1 and Arm 2 respectively (p =0.26). Median chimerism in the bone marrow was 98% (15 - 100) and 100% (4 - 100) on Arm 1 and Arm 2 respectively (p = 0.84). This was maintained at Day +80. Acute graft versus host disease (GVHD) grades II - IV was seen in 84% (n = 21) and 68% (n = 15) of patients on Arm 1 and 2 respectively with 5% and 12% grade III-IV GVHD in the respective arms. Chronic GVHD was seen in 40% of patients on Arm 1 (8 mild, 2 moderate) and 23% on Arm 2 (3 mild, 1 moderate, 1 severe). Overall survival at 1 year in Arm 1 was 43% (95% CI: 22-62%) and Arm 2 was 46% (95% CI: 20-69%). ConclusionsThe goal of this RIC UCBT study was to assess engraftment rates by neutrophil recovery and Day +28 chimerism in patients at low versus high risk of graft rejection. Although time to neutrophil recovery was significantly faster in patients with low risk of graft failure, patients at high risk of rejection achieved a similar incidence of full donor chimerism at Day +28 as those with low risk of graft rejection. Using Day +28 chimerism as a measure of engraftment, patients deemed high risk of graft failure achieved early engraftment with UCBT following an RIC conditioning regimen containing 300cGy TBI. Disclosures:No relevant conflicts of interest to declare.

Double-Unit Cord Blood (CB) Transplantation Combined With Haplo-Identical CD34+ Cell-Selected PBSC Results In 100% CB Engraftment With Enhanced Myeloid Recovery

BackgroundDouble-unit CB transplantation (DCBT) has provided high rates of sustained donor engraftment in patients with hematologic malignancies. However, delayed engraftment is frequent with a median neutrophil & platelet recovery of 25 & 48 days, respectively, in adult DCBT recipients at our center. This delay is associated with increased transplant-related mortality (TRM). It is also associated with prolonged hospitalization with a median discharge time of +42 days (range 25-76) in recent adult myeloablative DCBT recipients. MethodsWe investigated the combined transplantation of a 4-6/6 HLA-A,-B antigen, -DRB1 allele matched double-unit CB allograft (infused on day 0) with peripheral blood stem cell derived Miltenyi column selected haplo-identical CD34+ cells (haplo-CD34+, infused on day 0 or +1) to speed myeloid recovery. We used DCB grafts to facilitate comparison with historic/concurrent DCB controls transplanted without haplo-CD34+. ResultsOf 23 protocol eligible patients, 6/23 (26%) underwent DCBT only due to the lack of any suitable haplo-identical donor. Thus, 17 patients [median 39 years (range 16-69), median 78 kg (range 63-133)] were transplanted 9/2012-6/2013 with DCB plus haplo-CD34+ cells for high-risk hematologic malignancies. Diagnoses included 12 acute leukemias & 5 lymphomas. Conditioning was myeloablative with CSA/MMF immune suppression & no ATG. Median infused CB TNC x 107/kg was 2.29 (larger unit, range 1.73-2.95) & 1.82 (smaller unit, range 1.26-2.48). Haplo-identical donors (median 37 years, range 19-71) had a median donor-recipient HLA-match of 5/10 (range 5-7). 15 patients received the targeted infused haplo-CD34+ cell dose of 3 x 106/kg whereas 2 each received haplo-CD34+ cell doses of 1 x 106/kg. The median infused haplo-CD3+ dose was 0.6 x 103/kg (range 0.3-1.6). One patient died on day 14. Of 16 remaining evaluable patients, all (100%) engrafted with a median neutrophil recovery of 13.5 days (range 11-31) in 14 patients who received 3 x 106/kg haplo-CD34+ cells, and 26 and 18 days in the 2 patients who received 1 x 106/kg haplo-CD34+ cells. Platelet recovery ≥ 20 × 109/l has occurred in 12/15 patients (median 27 days, range 18-46) to date. Serial chimerism results demonstrating the contribution of haplo-CD34+ cells & each CB unit to date is shown (Table). While myeloid recovery on day 14 was predominantly haplo-CD34+ cell mediated, one CB unit dominated by day 28 in both neutrophil & T-cell subsets. The median total donor chimerism was 100% the dominant CB unit by day 100. With a median follow-up of survivors of 5 months (range 1-10), to date 9 of 15 evaluable patients have developed grade II-IV aGVHD by day 100 (7 grade II, 1 grade III, 1 grade IV). One patient with refractory leukemia transplanted with disease has relapsed, & 4 have died of TRM (2 organ failure, 1 grade IV aGVHD, 1 CMV infection). Excluding early deaths, of patients who were discharged in the first 100 days (n = 13), the median day of discharge was day +33 (range 21-60). ConclusionsDouble-unit CBT supplemented by haplo-CD34+ cells is safe. The incidence of neutrophil engraftment is high & the speed of neutrophil recovery is enhanced compared with recent DCBT controls. A shorter time of initial hospitalization (9 days) has offset the cost of the addition of haplo-CD34+ cells. It is intriguing that the dominant CB unit can rapidly reject the haplo-identical donor. This may be facilitated by omission of ATG, and the determinants of the speed of haplo-donor rejection are under investigation. Whether the same results could be achieved with a single CB unit plus haplo-CD34+ cells requires investigation. Addition of haplo-CD34+ cells is also an alternative to expansion, although expansion remains an important strategy to augmenting myeloid recovery given some patients do not have any suitable haplo-identical donors. Disclosures:No relevant conflicts of interest to declare.

A Novel Reduced-Intensity Conditioning Regimen Induces a High Incidence of Sustained Donor-Derived Neutrophil and Platelet Engraftment after Double-Unit Cord Blood Transplantation

A preparative regimen of reduced intensity that can reliably engraft cord blood (CB) and can be used as an alternative to either high-dose myeloablative or nonmyeloablative conditioning is needed. We evaluated double-unit CB transplantation in 30 patients (median age, 56 years; range, 18 to 69) with acute leukemia or myelodysplasia using a regimen of cyclophosphamide 50 mg/kg, fludarabine 150 mg/m2, thiotepa 10 mg/kg, and 400 cGy total body irradiation with cyclosporine-A/mycophenolate mofetil immunosuppression. Ninety-seven percent of patients engrafted at a median of 26 days (range, 13 to 43), and 93% of patients had recovered platelets by day 180. Grades II to IV acute graft-versus-host disease (GVHD) incidence was 67% at day 180, and chronic GVHD was 10% at 1 year. Transplant-related mortality was 20% at day 180, and relapse was 11% at 2 years. Overall, 2-year disease-free survival (DFS) was 60% at 2 years. A hierarchy in DFS was seen according to the Sorror comorbidity score: 11 patients (median age, 55 years) with a score of 1 had a 2-year DFS of 82% compared with 62% in 9 patients (median age, 51 years) with a score of 2 to 3 and 40% in 11 patients (median age, 58 years) with a score of 4 to 5 (P = .13). This reduced-intensity regimen combined with double-unit CB transplantation reliably facilitates sustained donor engraftment without antithymocyte globulin. Although other approaches are needed in patients with high comorbidity scores, this regimen is highly effective in patients ≥50 years old who are otherwise reasonably fit. It also represents a promising alternative to high-dose conditioning in younger patients.

Graft-Specific HLA-Antibodies Do Not Influence Unit Dominance and Do Not Prevent High Rates of Sustained Donor Engraftment in Recipients of Double-Unit Cord Blood (CB) Transplantation

Graft-Specific HLA-Antibodies Do Not Influence Unit Dominance and Do Not Prevent High Rates of Sustained Donor Engraftment in Recipients of Double-Unit Cord Blood (CB) Transplantation

Negative Depletion of B Cells and T Cells Expressing the αβ Chain of the T-Cell Receptor (TCR) for Haploidentical Stem Cell Transplantation

Abstract 343 Introduction.Allogeneic hematopoietic stem cell transplantation (HSCT) from a HLA-haploidentical relative is a suitable option for patients (pts) lacking a compatible donor, either related or unrelated. The two main approaches for overcoming the obstacles of HLA barriers are based either on the infusion of large numbers of T-cell-depleted HSC or on intensive pharmacological prevention of graft-versus-host disease (GVHD). While for many years T-cell depletion (TCD) of the graft has been based on either immunomagnetic positive selection of CD34+ cells or on physical removal of all subsets of T cells by virtue of mAb, we and other groups have recently developed a novel method of ex vivo TCD based on the selective elimination of αβ+ T cells through labeling with a biotinylated anti-TCRαβ Ab, followed by incubation with an anti-biotin Ab conjugated to paramagnetic beads (Miltenyi Biotec, Germany). This approach also allows the removal of B cells to prevent post-transplant EBV-associated lymphoproliferative disease (PTLD). Here, we report the results of graft manipulation using this approach. Methods.Twenty-two children entered the study, 15 with hematological malignancies and 7 with non-malignant disorders. No post-transplant GvHD prophylaxis was employed. HLA-haploidentical family donors received G-CSF (12–16 μg/kg of body weight) to mobilize HSC prior to large-volume leukapheresis, which was commenced when circulating CD34+ HSC were >20 cells/μl. Cell therapy products containing up to 60×109 white blood cells (WBC) were processed according to the manufacturer’s protocol. In some cases, leukapheresis bags were stored overnight at 4°C in appropriate media at a WBC concentration <200×106/ml. Aliquots of the graft were used to enumerate residual αβ T cells and B cells, as well as other immune effector cells, including type 1 and 2 dendritic cell (DC) precursors, invariant NKT cells, classical CD14+CD16− and non-classical CD14+CD16+ monocytes. All TCR αβ+/CD19+cell-depleted grafts were re-infused within 2 hours from the end of processing. Results.Median recovery of CD34+ HSC and median number of infused CD34+ HSC were 99.3% (range 55.4–100) and 14.7×106/kg (range 7.9–37), respectively. The graft contained 3.9×106 CD3+ T cells/kg (range 0.9–30.9) and 0.08×106 B cells/kg (range 0.002–0.32). The log-depletion of αβ+ T cells was 4.5 (range 3.2–6.1), with a median number of transplanted αβ+ T cells equal to 36×103/kg (range 1–139.9). Patients received 36×106 CD56+ NK cells/kg (range 1.6–80.3) and 4.1×106 γδ+ T cells/kg (range 0.9–30.8). A median of 40.8% NK cells (range 30.3–60.2) co-expressed Tim-3, an activating co-receptor promoting IFN-γ production and being scarcely expressed on NK cells that reconstitute after allogeneic HSCT. The αβ/CD19-depleted grafts also contained DC1 and DC2 precursors, which were identified based on BDCA-1 (0.23% of all nucleated cells, range 0.02–2.4), BDCA-3 (0.93%, range 0.57–9.4) and BDCA-2 (0.66%, range 0.49–1.28) or BDCA-4 expression (0.69%, range 0.02–1.5), respectively. Invariant NKT cells were enumerated using mAb reacting against the TCR Vα24-Jα18 chain and were detected in minute percentages (<0.05% of all nucleated cells) within the graft. The αβ/CD19-depleted grafts were also enriched in non-classical CD14+CD16+ monocytes (13.7% of all CD14+cells, range 9.3–29.4), which have been reported to predict a reduced incidence of GVHD after allogeneic HSCT. All patients rapidly engrafted, the median time to reach 500 neutrophils and 50,000 platelets per μl of blood being 12 days (range 10–16) and 13 days (range 12–18), respectively. Only 2 pts developed skin grade I/II acute GVHD, while no pt had visceral acute GVHD. With a median follow-up of 6 months (range 2–8), no pt experienced EBV-related PTLD or died of transplant-related complications. Conclusions.The immunomagnetic removal of αβ+ T cells and B cells was effective and gave reproducible results. In all cases, a remarkable depletion of unwanted T and B cells was attained. The depleted graft contained high numbers of CD34+ HSC, as well as of immune effector cells implicated in the control of leukemia growth and GVHD, such as γδ+ T cells, NK cells, DC1, DC2 and non-classical CD14+CD16+ monocytes. From a clinical standpoint, the infusion of αβ/CD19-depleted grafts from HLA-haploidentical family donors was safe, resulting into sustained donor engraftment without life-threatening complications. Disclosures:No relevant conflicts of interest to declare.

Graft-Specific HLA-Antibodies Do Not Influence Unit Dominance and Do Not Prevent High Rates of Sustained Donor Engraftment in Recipients of Double-Unit Cord Blood Transplantation

AbstractAbstract 960 Background:Pre-transplant human leukocyte antigen (HLA)-antibodies have an established role in failed engraftment after single-unit cord blood (CB) transplantation (CBT). Their role in double-unit CBT (DCBT) engraftment, however, is more controversial. Some transplant centers advocate pre-transplant screening of the recipient for HLA-antibodies, and avoidance of units with the corresponding antigens if antibodies are detected. Methods:We evaluated the influence of pre-transplant HLA-antibodies on sustained donor neutrophil engraftment and unit dominance in 82 recipients (median 48 years, range 2–69) of 4–6/6 HLA-A, B antigen, DRB1 allele matched double-unit CB grafts, and transplanted for hematologic malignancies at MSKCC from July 2008 to July 2012. HLA-antibodies were measured by the HLA Laboratory of the American Red Cross Blood Service using Single Antigen Luminex beads and analyzed by HLA Fusion software. The cut-off for positive results was a normalized mean fluorescence intensity value > 1000. Results:Overall, 28/82 (34%) patients were positive for HLA-antibodies [16 (19.5%) had antibodies without graft specificity, and 12 (14.5%) had antibodies with graft specificity]. These patients were more likely to be female with acute leukemia and cytomegalovirus seropositive. All patients with graft-specific antibodies received myeloablative conditioning; 5 had antibodies against class I HLA, 6 against class II, and one patient had antibodies to both Class I/II. Moreover, of these 12 patients, 6 had antibodies against one unit, and 6 had antibodies against both units. Neutrophil engraftment according to antibody presence is summarized in the Table. 64 of 66 (97%) evaluable myeloablative DCBT recipients (Table 1A) engrafted at a median of 24 days (range 12–40); one patient without antibodies and one with antibodies against both units had primary graft failure, both in the setting of early onset multi-organ failure. Both patients were 100% donor with one unit but did not recover counts. Of the 6 patients with antibodies to one unit, 3 engrafted with that unit and 3 with the opposite unit. Of the 6 patients with antibodies against both units, one had clinical graft failure as described above, and the 5 others had sustained donor engraftment (4 with one unit and one with both). In engrafting myeloablative recipients, the median time to neutrophil recovery was 8 days slower in patients with graft-specific antibodies, but the engrafting unit in these patients also had the lowest infused dose: median CD34+ cell dose/kg if no antibodies 0.83 × 105/kg, non-specific antibodies 1.09 × 105/kg, and antibodies specific to graft 0.65 × 105/kg. In non-myeloablative recipients, 15/16 (94%) engrafted (Table 1B). The single patient with graft rejection and autologous recovery had HLA-antibodies that were not graft specific. Conclusions:11 of 12 double-unit CBT recipients with graft-specific antibodies engrafted successfully. While myeloablative recipients with graft-specific antibodies engrafted more slowly, this may be explained by a lower infused CD34+ cell dose of their engrafting units. Multivariate analysis of larger patient numbers will be required to further evaluate the effect of graft-specific antibodies on engraftment speed. At this time, however, the presence of graft-specific antibodies should not preclude DCBT, and whether their presence should influence graft selection is not clear. Furthermore, there is no suggestion that the presence of HLA-antibodies influences unit dominance after DCBT.TableSustained Donor Neutrophil Engraftment According to HLA-antibodies1A) Myeloablative Conditioning (n=67)Median (Range) Time to Neutrophil Recovery (> 0.5)N (%) Sustained EngraftmentNo antibodies (n=41)23 days (range 12–38)39/40 (1 non-evaluable)Antibodies: not graft-specific (n=14)23 days (range 12–37)14/14Antibodies: graft-specific (n=12)31 days (range 13–40)11/12Against engrafting unit (n=3)28 days (range 24–31)3/3Against non-engrafting unit (n=3)31 days (range 25–32)3/3Antibodies against both units (n=6)33 days (range 13–40)5/61B) Non-Myeloablative Conditioning (n=15)Median (Range) Time to Neutrophil Recovery (> 0.5)N (%) Sustained EngraftmentNo antibodies (n=13)10 days (range 8–20)13/13Antibodies: not graft specific (n=2)19 days in 1 patient (other had graft failure/autologous recovery)1/2Antibodies: graft specific (n=0)-- Disclosures:Giralt:Celgene: Honoraria, Research Funding.

A Novel Reduced Intensity Conditioning Regimen Induces a High Incidence of Sustained Donor Neutrophil and Platelet Engraftment After Double-Unit Cord Blood Transplantation

AbstractAbstract 4155 Introduction:Cord blood (CB) transplant (CBT) can be curative for patients with high-risk hematologic malignancies. However, patients of older age and/or with significant co-morbidities do not tolerate CBT with high-dose myeloablative conditioning. Non-myeloablative (NMA) conditioning can reduce transplant-related mortality (TRM) and extend transplant access to older or infirm patients, but it is limited by the risks of graft rejection in patients without extensive prior chemotherapy and relapse. While the addition of anti-thymocyte globulin (ATG) may reduce rejection, it increases the risk of viral infections, including Epstein-Barr virus lymphoproliferative disease, and may also increase relapse risk. Methods:We investigated the safety and efficacy of an ATG-free regimen of intermediate intensity prior to double-unit CBT in 30 patients with acute leukemias and myelodysplasia. Units were 4–6/6 HLA-A, B antigen, DRB1 allele matched to the patient. The conditioning regimen included 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), total body irradiation 200 cGy × 2 (days -2 and -1), and cyclosporine-A/mycophenolate mofetil immunosuppression. The indication for this regimen was one or more risk factors for TRM including age > 50 years, extensive prior therapy, and/or significant co-morbidities. The hematopoietic cell transplant co-morbidity index (HCT-CI) score of Sorror was retrospectively assigned. Results:The median age was 56 years (range 18–69). All but one patient had high-risk disease. Twenty-one had AML (16 CR1, 5 CR2) with all CR1 patients having high-risk features, including high-risk cytogenetics (n = 3), FLT-3 ITD mutation (n = 5), therapy-related disease or prior MDS (n = 6), and/or > 3 consecutive induction chemotherapies (n = 2). Five had ALL (4 CR1, 1 CR3); the 4 in CR1 had BCR/ABL mutations (n = 3) or prior refractory CNS disease (n = 1). Four patients had MDS with 3 having an IPSS score > 2. The median HCT-CI score was 2.5 (range 1–5). Median infused TNC doses were 2.6 (larger unit) and 1.9 (smaller unit) × 107/kg, respectively. Ninety-seven percent of patients engrafted (95%CI: 87–100) at a median of 26 days (range 13–43). The median day 21 total donor bone marrow chimerism was 100% (range 71–100). All surviving patients were 100% donor by day 100, and sustained hematopoiesis has been mediated by a single unit in all but one patient. The cumulative incidence of platelet recovery > 20 × 109/L by day 180 was 93% (95%CI: 83–100), and occurred at a median of 46 days (range 30–79). Day 180 TRM and 2-year relapse incidences were 20% and 11%, respectively. With a median 26.5 months (range 9–53) follow-up of survivors, the 2-year overall survival and disease-free survival (DFS) are both 60% (95%CI: 44–82). There was a hierarchy in 2-year DFS according to the Sorror HCT-CI score (Figure): the 11 patients (median age 55 years) with a score of 1 had a DFS of 82%. This compared with a 2-year DFS of 62% in the 9 patients (median age 51 years) with a score of 2–3, and 40% in the 11 patients (median age 58 years) with a score of 4–5 (p = 0.13). Discussion:This reduced intensity regimen combined with double-unit CBT reliably facilitates sustained donor engraftment without ATG. This regimen is associated with less toxicity than high-dose myeloablative conditioning. While other approaches are needed in patients with high comorbidity scores, this regimen is highly effective in older patients who are otherwise reasonably fit, as evidenced by the 82% 2-year DFS in patients with a median age of 55 years. Given the relatively low risk of relapse, it also represents a promising alternative to high-dose conditioning in younger patients. [Display omitted] Disclosures:Giralt:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millenium: Membership on an entity's Board of Directors or advisory committees.

The Use of Back-up Units to Enhance the Safety of Unrelated Donor Cord Blood Transplantation

The inability to obtain additional stem cells is a disadvantage of unrelated donor cord blood transplantation (CBT). Moreover, in the event of problems with unit shipment, compromised unit quality, thaw mishaps, or graft failure, the time to secure a back-up graft could be unacceptable. Emergent shipment of 1 to 2 back-up units that have been previously typed and reserved could overcome this limitation. However, the advantages of this approach are not established. Therefore, we present our use of back-up units over a 5.5-year period. Six of 121 CBT recipients (5%) required back-up unit infusion. Indications included shipment mishaps (n = 2), poor unit viability (n = 2), significant infusion reaction (n = 1), and graft failure (n = 1). Lack of back-up units would have caused transplantation delay or infusion of inferior-quality units. Five of the 6 patients achieved sustained donor engraftment. We demonstrate that back-up units are emergently required in a significant minority of patients, supporting the incorporation of at least 1 back-up unit in cord blood (CB) selection algorithms to enhance CBT safety.

“No Wash” Albumin-Dextran Dilution for Double-Unit Cord Blood Transplantation (DCBT) Is Safe with Appropriate Management and Results in High Rates of Sustained Donor Engraftment

“No Wash” Albumin-Dextran Dilution for Double-Unit Cord Blood Transplantation (DCBT) Is Safe with Appropriate Management and Results in High Rates of Sustained Donor Engraftment

Mixed Chimerism after Allogeneic Stem Cell Transplantation – Focus on Double Cord Blood Transplantation

Allogeneic hematopoietic Stem Cell Transplantation (ASCT) is well established as a curative treatment for many hematological malignancies and non-malignant disorders. The aim of ASCT in these diseases is to achieve sustained donor engraftment to fight leukemic cells in malignant disease, improve hematopoietic function, provide immune competence or normalize enzyme deficiency. Peripheral blood or bone marrow is commonly used to monitor engraftment after ASCT. The presence of mixed donor/recipient chimerism after transplantation, donor/donor chimerism after double cord blood transplantation can be used and interpreted differently based on the initial disease status. In patients with malignant diseases, chimerism is primarily used to detect early relapse but can also indicate threatening rejection. In individuals with non malignant disease, chimerism is merely used to monitor successful engraftment. After double cord blood transplantation, the unique situation with two existing donor immune systems can occur. Most often one of the immune systems rapidly succumbs with one immune system prevailing, but in certain situations mixed donor/donor chimerism can exist for prolonged periods. This review describes the importance of mixed chimerism and the possible interpretation after ASCT in patients with both malignant and non-malignant diseases. It also focuses specifically on the situation and mechanisms donor/ donor chimerism after double cord blood transplantation.