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The combination of ponatinib, a third-generation BCR::ABL1 tyrosine kinase inhibitor, with hyper-CVAD chemotherapy resulted in high rates of complete molecular remissions and survival, without the need for stem cell transplantation (SCT) in most patients with Philadelphia chromosome(Ph)-positive acute lymphocytic leukemia (ALL). Confirming these results in a large cohort of patients with longer follow-up would establish this regimen as a new standard of care. Adults with newly diagnosed Ph-positive ALL were treated with the hyper-CVAD regimen. Ponatinib was added as 45 mg daily × 14 during induction, then 45 mg daily continuously (first 37 patients) or 30 mg daily continuously, with dose reduction to 15 mg daily upon achievement of a complete molecular response (CMR; absence of a detectable BCR::ABL1 transcript by quantitative reverse transcription polymerase-chain reaction at a sensitivity of 0.01%). Maintenance therapy consisted of daily ponatinib and vincristine-prednisone monthly for 2 years, followed by daily ponatinib indefinitely. Twelve intrathecal injections of cytarabine alternating with methotrexate were given as central nervous system prophylaxis. The trial is registered on clinicaltrials.gov with the identifier NCT01424982. Eighty-six patients were treated. Their median age was 46 years (range, 21-80). All 68 patients with active disease at the initiation of therapy achieved complete response (CR) The cumulative CMR rate was 86%. Twenty- patients (23%) underwent allogeneic SCT. With a median follow-up of 80 months (range, 16-129 months), the estimated 6-year event-free survival rate was 65% and the overall survival rate was 75%. There was no difference in outcome by performance of allogeneic SCT in first CR. Common grade 3-5 adverse events included infection (n = 80, 93%), increased liver transaminases (n = 26, 31%) and total bilirubin (n = 13, 15%), hypertension (n = 15, 17%), pancreatitis (n = 13, 15%), hemorrhage (n = 12, 13%), and skin rash (n = 9, 10%). Two ponatinib-related deaths from myocardial infarction (3%; at months 2.6 and 4.3, respectively; both in CR) in the first 37 patients treated led to the ponatinib dose-modifications mentioned earlier, with no further ponatinib-related deaths observed. The long-term results of ponatinib and hyper-CVAD continue to demonstrate excellent outcome results and acceptable safety data, indicating that this strategy is another standard of care approach in frontline Ph-positive ALL.

When multiple haploidentical donors are available for transplantation, those of younger generations are generally selected over those of older generations. However, it is unclear who is the optimal donor when selecting candidates from within a generation, such as father versus mother, son versus daughter, or brother versus sister. Although traditionally male donors are favored over female donors, particularly for male recipients, and significant associations of individual HLA mis(matches) on outcomes are being increasingly recognized, the hierarchy of factors for donor selection is indeterminate. To assess whether HLA factors take precedence over non-HLA factors and to isolate the influence of specific characteristics on outcomes, we analyzed 412 patients stratified by donor relationship: child donor (son [n = 202] versus daughter [n = 96]), parent (father [n = 28] versus mother [n = 29]), and sibling (noninherited maternal [NIMA; n = 29] versus paternal [NIPA; n = 28] mismatched). Among siblings, NIMA mismatch was associated with a lower risk of acute graft-versus-host disease (aGVHD); B-leader mismatch was associated with high nonrelapse mortality (NRM), poor progression-free survival, and a trend toward poor overall survival (OS), whereas A-mismatch was associated with lower aGVHD. Among parent donors, the relationship did not impact any outcome; B-leader mismatch was associated with higher NRM and a trend toward poor OS, whereas A-mismatch was associated with lower NRM and improved progression-free survival and OS. Among child donors, no individual HLA mismatch was predictive of any outcome, and daughter donors were not associated with any adverse outcomes in multivariate analyses. Our data suggest that certain HLA factors may be more significant in some cases and should be given priority over simply selecting a donor based on relationship/sex.

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis is increasing in patients undergoing HLA-matched sibling (MSD) or unrelated (MUD) donor hematopoietic cell transplantation (HCT), but data about its comparative efficacy against the traditional GVHD prophylaxis are scarce. Two broad questions assessed in this study were (a) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (without ATG) in the MSD and (b) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (with ATG) in the MUD group. This retrospective single-center study analyzed the outcomes of 964 patients who received Tac/MTX (n = 578) versus PTCy-based (n = 386) GVHD prophylaxis. All MUD recipients in the Tac/MTX group also received ATG; thus separate analyses were conducted for MSD (n = 412) and MUD (n = 552) cohorts. In the MUD cohort, 306 patients received Tac/MTX/ATG and 246 received PTCy-based GVHD prophylaxis. In the MSD cohort, 272 received Tac/MTX and 140 received PTCy-based prophylaxis. Both PTCy groups included somewhat older patients than the Tac/MTX groups and more patients had myeloid malignancy (85%-90% versus 59%-64%, respectively). A majority of patients in all groups received myeloablative conditioning and peripheral blood graft. Both PTCy groups had a significantly delayed neutrophil engraftment, higher risk of hemorrhagic cystitis, and higher risk of bacterial infections than the Tac/MTX groups. The risks of viral infections and related deaths were significantly higher in Tac/MTX group in the MUD cohort. In multivariate analysis, the risk of grade III-IV acute GVHD was similar in PTCy and Tac/MTX groups in both MSD and MUD cohorts, but the risk of chronic GVHD was significantly lower with PTCy in the MSD cohort. PTCy was associated with a significantly lower risk of non-relapse mortality and better progression-free survival in the MUD. PTCy was associated with improved GVHD-free relapse-free survival in both MSD and MUD groups. Our data suggest a benefit of using PTCy-based GVHD prophylaxis in both MSD (versus Tac/MTX) and MUD (versus Tac/MTX/ATG) HCT.

Patients with B-lineage acute lymphoblastic leukemia (ALL) are at high-risk for relapse after allogeneic hematopoietic cell transplantation (HCT). We conducted a single-center phase 2 study evaluating the feasibility of 4 cycles of blinatumomab administered every 3 months during the first year after HCT in an effort to mitigate relapse in high-risk ALL patients. Twenty-one of 23 enrolled patients received at least 1 cycle of blinatumomab and were included in the analysis. The median time from HCT to the first cycle of blinatumomab was 78 days (range, 44 to 105). Twelve patients (57%) completed all 4 treatment cycles. Neutropenia was the only grade 4 adverse event (19%). Rates of cytokine release (5% G1) and neurotoxicity (5% G2) were minimal. The cumulative incidence of acute graft-versus-host disease (GVHD) grades 2 to 4 and 3 to 4 were 33% and 5%, respectively; 2 cases of mild (10%) and 1 case of moderate (5%) chronic GVHD were noted. With a median follow-up of 14.3 months, the 1-year overall survival (OS), progression-free survival (PFS), and nonrelapse mortality (NRM) rates were 85%, 71%, and 0%, respectively. In a matched analysis with a contemporary cohort of 57 patients, we found no significant difference between groups regarding blinatumomab’s efficacy. Correlative studies of baseline and posttreatment samples identified patients with specific T-cell profiles as “responders” or “nonresponders” to therapy. Responders had higher proportions of effector memory CD8 T-cell subsets. Nonresponders were T-cell deficient and expressed more inhibitory checkpoint molecules, including T-cell immunoglobulin and mucin domain 3 (TIM3). We found that blinatumomab postallogeneic HCT is feasible, and its benefit is dependent on the immune milieu at time of treatment. This paper is posted on ClinicalTrials.gov, study ID: NCT02807883.

Adapted from the haploidentical hematopoietic stem cell transplantation (HCT) literature, post-transplantation cyclophosphamide (PTCy) is being used increasingly with HLA-matched donors, generally with a calcineurin inhibitor, such as tacrolimus (Tac), and with or without mycophenolate mofetil (MMF). Owing to its immunosuppressive and potentially antitumor and antimicrobial properties, MMF is an attractive drug; the benefit gained when it is used with PTCy/Tac remains unclear, however. To assess this, we compared PTCy/Tac (n = 242) and PTCy/Tac/MMF (n = 144) regimens in recipients of HLA-matched donor transplantation. In multivariate analysis, the PTCy/Tac/MMF group had a significantly higher risk of grade II-IV acute graft-versus-host disease (aGVHD) (hazard ratio [HR], 2.1; 95% confidence interval [CI], 1.6 to 2.8; P.001), and steroid-refractory/dependent aGVHD (HR, 4.8; 95% CI, 2.4 to 9.6; P.001), yet a significantly lower risk of relapse (HR, .5; 95% CI, .3 to .9; P = .009) and better progression-free survival (PFS) (HR, .7; 95% CI, .5 to .9; P = .04). There were no differences in the risk of grade III-IV aGVHD, chronic graft-versus-host disease (cGVHD), nonrelapse mortality, or overall survival. MMF was associated with prolonged neutrophil engraftment by 2 days and an elevated risk of bacterial infection. In an exploratory stool microbiome analysis (n = 16), we noted a higher relative abundance of β-glucuronidase-producing bacteria in the MMF group, which may have a role in the pathogenesis of MMF-related GVHD. Our data suggest that the addition of MMF to PTCy/Tac for HLA-matched donor HCT does not provide any advantage for GVHD prevention. Further studies are needed to decipher this mechanism and understand its role with PTCy-based prophylaxis.

Secondary central nervous system large B-cell lymphoma (SCNSL) is rare, with a generally poor prognosis. There is limited data about the role of autologous stem cell transplantation (ASCT) in these high-risk patients. We explored in this study treatment outcomes and prognostic factors for patients with SCNSL who underwent ASCT. We included all consecutive patients who underwent ASCT at our institution. Primary endpoints were progression-free survival (PFS) and overall survival (OS). One-hundred two patients were identified. Median age at transplant was 56 (range, 21-71) years. With a median follow-up of 56 (range, 1-256) months, the median PFS and OS were 40 and 88 months, respectively. The 4-year PFS and OS were 48% and 57%, respectively. In univariate analysis, complete remission (CR) at transplant, prior lines of therapy (≤2), normal lactate dehydrogenase, and parenchymal involvement were significantly associated with improved PFS. For OS, only CR at transplant and ≤2 prior lines of therapy were associated with improved survival. On multivariable analysis for PFS, CR at transplant (hazard ratio [HR], 0.278; 95% CI, 0.153-0.506; P ≤ .0001) and ≤2 prior lines of therapy (HR, 0.485; 95% CI, 0.274-0.859; P = .0131) were significantly associated with superior PFS. Similarly, CR at transplant (HR, 0.352; 95% CI, 0.186-0.663; P = .0013) and ≤2 prior lines of therapy (HR, 0.476; 95% CI, 0.257-0.882; P = .0183) were associated with improved survival. In the largest single-center study, our findings indicate that ASCT is associated with durable responses and prolonged survival in patients with SCNSL. Patients in CR at transplant and those who received ≤2 lines of therapy have particularly excellent outcomes.

Minimal residual disease (MRD) assessment predicts survival for patients with newly diagnosed acute lymphoblastic leukemia (ALL). Its significance in relapsed/refractory ALL is less clear.This study identified 78 patients with relapsed/refractory B-cell ALL who achieved a morphologic response with inotuzumab ozogamicin (n = 41), blinatumomab (n = 11), or mini-hyperfractionated cyclophosphamide, vincristine, and doxorubicin plus inotuzumab (n = 26) during either salvage 1 (S1; n = 46) or salvage 2 (S2; n = 32) and had undergone an MRD assessment by multiparameter flow cytometry at the time of remission.MRD negativity was achieved in 41 patients overall (53%). The MRD negativity rate was 57% in S1 and 47% in S2. Among patients in S1, achieving MRD negativity was associated with longer event-free survival (EFS; median, 18 vs 7 months; 2-year EFS rate, 46% vs 17%; P = .06) and overall survival (OS; median, 27 vs 9 months; 2-year OS, 52% vs 36%; P = .15). EFS and OS were similar in S2, regardless of the MRD response. Among MRD-negative patients who underwent allogeneic stem cell transplantation (SCT), EFS and OS were superior for those who underwent SCT in S1 rather than S2 (P = .003 and P = .04, respectively). Patients in S1 who achieved MRD negativity and subsequently underwent SCT had the best outcomes with a 2-year OS rate of 65%.Patients with relapsed/refractory ALL who achieve MRD negativity in S1 can have long-term survival. Patients in S2 generally have poor outcomes, regardless of their MRD status. Cancer 2017;123:294-302. © 2016 American Cancer Society.

BACKGROUND Decitabine is a hypomethylating agent that has activity in patients with leukemia. The authors combined decitabine with busulfan and cyclophosphamide as a conditioning regimen prior to allogeneic hematopoietic stem cell transplantation. METHODS Patients with high-risk acute myeloid leukemia (AML) (n = 12 patients); chronic myelomonocytic leukemia (CMML) (n = 1 patient); acute lymphocytic leukemia (ALL) (n = 1 patient); or late chronic phase, accelerated, or blastic phase chronic myelogenous leukemia (n = 9 patients) were eligible for the study. The treatment plan was comprised of busulfan, 12 mg/kg orally; cyclophosphamide, 100 mg/kg (n = 4 patients) or 120 mg/kg (n = 19 patients); and decitabine, intravenously at 3 dose levels: 400 mg/m2 (n = 10 patients), 600 mg/m2 (n = 8 patients), and 800 mg/m2 (n = 5 patients). Donors were human leukocyte antigen-identical siblings in all cases, and all but one patient received peripheral blood stem cells. Graft-versus-host disease (GVHD) prophylaxis was tacrolimus based in all but one patient. RESULTS The median time to neutrophil and platelet engraftment was 12.5 days and 17.5 days, respectively. Twenty-one patients were engrafted and achieved disease remission. At a median of 3.3 years posttransplantation, 26% of patients (40% of patients with AML) were alive and disease free. The median survival for the group was 17.2 months, and the disease free survival for the group was 8.9 months. Causes of death were disease recurrence (nine patients), chronic GVHD (four patients), infections (three patients), and acute GVHD (one patient). The 100-day mortality rate was 9%. No decitabine dose-limiting toxicity was documented. The treatment-related mortality rate at 3 years was 35%. Responders were treated at all three decitabine dose levels, and no dose-response correlation was observed. CONCLUSIONS There was a high response rate with low treatment-related mortality, with 26% of patients alive in remission 3.3 years after transplantation. Cancer 2003;97:1242–7. © 2003 American Cancer Society. DOI 10.1002/cncr.11184

The purpose of this study was to perform a detailed analysis of the charges associated with chemomobilization and remobilization of autologous hematopoietic stem cells (HSCs) and to quantify medical costs and resource utilization associated with these procedures.Patients with lymphoma underwent chemomobilization with ifosfamide and etoposide with or without rituximab (IE ± R). Patients with multiple myeloma (MM) received a modified hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone (hyper-CVAD) regimen after failing to mobilize with growth factors only.Between January 2004 and October 2006, 98 patients with lymphoma underwent HSC mobilization with IE ± R. Mobilization with IE ± R was effective, with 90.8% of patients collecting at least 2 × 10(6) CD34+ cells/kg. The total charges for treatment were $27,996 and $37,667 for patients mobilized with IE and IE + R, respectively. Hospital readmission for complications occurred in 26.5% of patients, resulting in additional charges of $10,356. The preapheresis procedure charge was estimated to be $2522, the charge for a 2-day apheresis session was $5160, and the postapheresis phase resulted in charges of $8040. Our analysis determined that reducing apheresis by 1 day has the potential to save $6600. We also performed a retrospective analysis of 16 patients with MM remobilized with a modified hyper-CVAD regimen. Remobilization was successful, with 87.5% of patients. Our analysis determined that mobilization, preapheresis, apheresis, and postapheresis phase charges were $24,968, $2522, $6158, and $12,060, respectively.Optimization of HSC mobilization regimens to reduce failure rates would not only benefit patients but also reduce the overall medical costs.

High-dose myeloablative therapy with allogeneic hematopoietic transplantation is an effective treatment for hematologic malignancies, but this approach is associated with a high risk of complications. The use of relatively nontoxic, nonmyeloablative, or reduced-intensity preparative regimens still allows engraftment and the generation of graft-vs-malignancy effects, is potentially curative for susceptible malignancies, and reduces the risk of treatment-related morbidity. Two general strategies along these lines have emerged, based on the use of (1) immunosuppressive chemotherapeutic drugs, usually a purine analog in combination with an alkylating agent, and (2) low-dose total body irradiation, alone or in combination with fludarabine (Fludara).

Introduction Haploidentical stem cell transplant (haplo-HCT) is a therapeutic option for patients without matched donors. We aimed to analyze outcomes of patients with AML/MDS treated with melphalan-based conditioning and different donors at our institution and determine the factors associated with survival. Methods All 246 patients receiving an allograft for AML/MDS between 01/2005 and 09/2012 were included in this retrospective analysis. Conditioning regimen consisted of melphalan 100 mg/m2 (Mel100) (N=37) or 140 mg/m2, (Mel140) (N=209) and fludarabine 120-240 mg/m2 +/- thiotepa (N=50). Graft versus host disease (GvHD) prophylaxis had consisted of tacrolimus and mini-methotrexate +/- ATG for matched transplants, and post-transplant cyclophosphamide (PTCy), tacrolimus and mycophenolate mofetil (MMF) for T-cell replete (TCR) haploidentical transplants. A small number of patients (N=19) received a T-cell depleted (TCD) haplo-HCT using CD34+ selected graft as previously described by us. We analyzed transplant outcomes and performed lymphocyte reconstitution on available samples from MRD, MUD and TCR-haplo recipients between day+30 and +365 post-transplant. Incidences in GvHD were assessed using Fisher's exact test. Differences in CD3+ T-cell counts were assessed using Kruskal-Wallis test. Kaplan-Meier survival curves were used to estimate OS, and PFS and the log-rank test was used to assess differences between groups; NRM was determined by the cumulative incidence (CI) function using the competing risks method. The competing risk included was relapse. Differences in cumulative incidence NRM between groups were assessed using Gray's test. Results Median follow-up for survivors was 31 months. PFS for the entire cohort at 1 year was 44% and OS was 53%. No differences in outcomes (NRM, relapse, PFS) were noted for patients treated with ablative (140 mg/m2) or reduced dose (100mg/m2) of melphalan, both overall and for patients in remission(Fig.1A). To appreciate the impact of different donor type of transplant outcomes we analyzed outcomes of patients treated in remission (CR1+CR2) (N=78). Pre-transplant characteristics were well balanced for patients who received a MSD, MUD or haplo donor except TCR haplo patients received almost exclusively a bone marrow graft (95%) and TCD-haplo patients had a younger median age at transplant (27.5 years; P=0.0004). For patients in remission at transplant, 1 year PFS was 67% (Mel100) vs. 69% (Mel140) (P=0.97). Based on donor type, the 1-year PFS were 80% for MRD (N=25) recipients, 76% for MUD (N=26) recipients, 64% for TCR haplo (N=19) and only 13% for TCD-haplo recipients (N=8) (P=0.003) (Fig.1B). In univariate and multivariable analyses for PFS, the only significant factors associated with worse survival were cytogenetic risk category and the use of a TCD haplo-HCT (Fig.1C). Using MUD donor as reference, no differences were detected in PFS when compared with recipients of MRD or TCR-haplodonors, while TCD-haplo group did significantly worse (multivariable analysis; P=0.006). The CI NRM rates for CR1+CR2 patients at 100 days were 0% (MRD), 5% (TCR-haplo), 4% (MUD), 38% (TCD-haplo), and at one year were 8% (MRD), 18% (TCR-haplo), 8% (MUD), and 75% (TCD-haplo) (P=0.0008). Incidence of severe aGvHD was 0% (TCR-haplo), 4% (MUD, MRD), and 50% (TCD-haplo) (P=0.0008). Overall chronic GvHD incidence was lowest in the TCR-haplo group (16%) and highest in the MRD group (48%). TCD-haplo and MUD had cGvHD rates of 25% and 34%, respectively (P=0.16). As shown in Fig.1D, TCR-haplo recipients reconstituted lymphocyte subsets with a kinetic trend similar to MUD and MRD recipients. All patients achieved normal CD3+ T-cell counts around day 180 post-transplant, with an early recovery of CD8+ T cells. TCR-haplo recipients did not have a significant inferior reconstitution for CD4+, CD8+, CD3-CD56+ and CD3-CD20+ cells at any time point between day 90 and day 365. Conclusions Outcomes of patients with AML/MDS treated with melphalan-based conditioning are negatively influenced by cytogenetic risk category and the use of a TCDhaplo donor, while melphalan dose and the use of a TCR haplo-HCT vs. matched donor did not negatively impact survival. Disclosures: No relevant conflicts of interest to declare.

Introduction The persistence of anti-donor isohemagglutinins in Major ABO mismatched allogeneic stem cell transplantation (HCT) leads to pure red cell aplasia (PRCA). In our previous report of 12 patients with PRCA, severe pancytopenia was observed in one patient who eventually had a second transplant (Aung et al. B J Haematol 2013 Mar; 160(6):798-805). Furthermore, ABO antigens are expressed on or adsorbed from plasma on granulocyte and platelets and these may be affected by isohemagglutinins. To further investigate this observation we analyzed a larger cohort of patients with PRCA to determine the frequency of pancytopenia and natural history of pancytopenia in patients with PRCA after Major ABO incompatible HCT. Patients and Methods We reviewed 758 patients who received a Major ABO-mismatched HCT between January 2003 and December 2012 at our institution. Pure red call aplasia was determined to be present when the bone marrow biopsy on post-transplant day 30 demonstrated absent or nearly absent erythroid precursors with absence of donor red cells on forward red cell typing of the recipient and the recipient being red cell transfusion dependent. Pancytopenia was defined as ANC < 1.5 x 109/L or requiring G-CSF, Platelets < 50 x 109/L or transfusion dependent, and PRCA with red cell transfusion dependence as above at 90 days after allogeneic SCT. Results 83 patients had PRCA. Of these 16 (19%) had pancytopenia at day 90 after transplant. None of these patients had any other reason for persistent pancytopenia like CMV or other viral infection or use of drugs like ganciclovir or disease recurrence. On post-transplant day 90, median absolute neutrophil counts (ANC) was 1.01 K/UL with 15 (94%) patients having intermittent G-CSF and median platelet count was 14 KL/UL (range 6-49) with 13(81%) patients platelet transfusion dependent. All patients were red cell transfusion dependent. Of the 16 PRCA patients with pancytopenia, 2 (12%) received a second transplant due to persistent pancytopenia/graft failure and 2 (12%) relapsed. 2 (12%) patients have still not recovered their platelet counts despite red cell and ANC recovery. In the remaining 10 (63%) patients, neutropenia and thrombocytopenia resolved after resolution of PRCA. Red cell recovery occurred at a median of 226 (95-549) days post transplant, ANC recovered at median of 325 (105-1080) days post-transplant, and Platelets recovered at median of 296 (94-2738) days post-transplant. Conclusion Severe pancytopenia is frequently (19%) associated with PRCA in Major ABO incompatible HCT. Neutropenia and thrombocytopenia resolve after resolution of red cell aplasia in the majority of patients. Disclosures: Andersson: Otsuka Pharmaceuticals: Research Funding. Qazilbash:Celgene: Membership on an entity’s Board of Directors or advisory committees; Millennium: Membership on an entity’s Board of Directors or advisory committees. Shah:Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding.

To the Editor: In 1995 we reported on 10 patients with a history of advanced, refractory low-grade lymphoma who had undergone allogeneic transplantation. Seven patients had follicle-center lymphomas, two had small lymphocytic lymphomas, and one had a mantle cell lymphoma. Two patients had died from transplant-related toxicity and eight had obtained remissions. With a median follow-up of 27 months (range, 11 to 62 months), no recurrences had occurred. Figure 1 shows the survival and disease-free survival of this patient cohort as of October 1999. Currently, the median follow-up is 6 years after transplantation (range, 5 to 9 years), and only one patient has developed disease progression. That patient is currently in remission 8 years after the initial transplant and 4 years after a second allogeneic transplantation. That same patient developed extensive chronic graft-versus-host disease after transplantation and developed disease recurrence while receiving chronic immunosuppression. Two additional patients have developed limited chronic graft-versus-host disease, and one patient has developed aseptic hip necrosis. No other posttransplant complications have occurred. Since our initial publication, several groups have confirmed the ability to induce remissions of low-grade lymphoma with allogeneic transplantation, but the median follow-up in these studies was, at best, 3 years. Hence, the possibility remained that, as with autologous transplantation, late recurrences and complications such as secondary MDS would affect long-term outcome. However, our data, admittedly obtained on a small patient sample, indicate the possibility of durable remissions in the majority of survivors of allogeneic transplantation. Confirmation of these data in larger studies with long follow-up is necessary.

CBT is frequently complicated by delayed and failed engraftment when compared to other sources of hematopoietic stem cell support. Strategies to improve engraftment include double CBT and ex-vivo expansion. We are comparing these approaches in a randomized, prospective fashion. Patients (N=71) were randomized to receive either two unmanipulated (UNM) CB units (N=36) or one UNM unit and one unit which was EXP ex-vivo (N=35). The majority of CB units were 4/6 HLA matches. Methods: Diagnoses were AML/MDS (N=25; 35%), ALL(N=17; 24%), NHL(N=10; 14%), HD(N=7; 10%), CML (N=5; 7%), and CLL(N=7; 10%). Patients (Table 1) had primarily advanced disease, with a median of 3 (1–8) prior regimens including autotransplants in 22%. Preparative regimens included ATG and either myeloablative fludarabine plus dose-adjusted busulfan (N=13; myeloid diseases), or melphalan and thiotepa (N=28); patients not eligible for high-dose therapy received non-myeloablative fludarabine plus cyclophosphamide and 200 Gy TBI (=27) or melphalan (n=3). GVHD prophylaxis was tacrolimus plus either 3 doses of 5 mg/m2 methotrexate or MMF (table 1). Ex-vivo expansion: the smallest unit was CD133-selected using the CliniMACS device (day −14). The T cell-containing CD133-negative fraction was frozen. The CD133+ fraction was cultured for 14 days in media containing SCF, G-CSF and TPO. On day 0, the 2nd UNM unit was infused, followed by the CD133-negative and the EXP fractions. Results. Infused median total nucleated cells (TNC)×107/Kg was 3.5 and 3.6, and median CD34×105/Kg was 1.8 and 1.1, respectively for EXP and UNM pts. Median TNC fold-expansion was 23 (0.44–275) and for CD34+ cells, 2.3 (0–957). The median ex-vivo fold expansion of patients that engrafted platelets was higher than patients that did not engraft (23 (range, 0.4–275) versus 9.3 (range, 1.1–63), P=0.4). Patients that received EXP cells and a reduced-intensity regimen engrafted neutrophils in a median of 7 days (range, 4–15 days; n=14) versus 14 days (range, 5–32 days; n=12) in the UNM arm (P=0.05). Thirty-four patients are alive (48%) with a median follow up of 11.3 mo (range, 2–49 months). Twenty-four patients have relapsed (34%). Chimerism analysis showed that ultimately one CB unit dominated in all patients, on both the UNM and EXP arms of the trial. For the EXP arm the majority of patients had evidence of expanded CB chimerism posttransplant ranging from 7–82%. In half of those patients, the expanded CB unit predominated over the unmanipulated unit for 2–12 months posttransplant (52–87%), followed by gradual predominance of the unmanipulated CB unit by 14 months in all patients. Conclusion: Conclusion: EXP CBT was safe. The range of fold-expansion was highly variable. Accrual continues and we are focusing on strategies which improve CB expansion. | | Expanded | Unmanipulated | P | |:----------------------------------:| -------------- | ------------- | ---- | | Complete remission at UCBT | 41% | 59% | 0.09 | | Median weight | 85 (20–168) | 76 (15–144) | 0.18 | | Median age | 43 (4–70) | 38.1 (2–73) | 0.4 | | Ablative preparative regimen | 47% | 68% | 0.09 | | GVHD prophylaxis with methotrexate | 32% | 30% | NS | | Time to ANC500 (median/95%CI) | 14 days (4–32) | 17 (5–45) | | | | | | 0.2 | | Proportion engrafting ANC500 | 80% | 86% | | | | | | NS | | Time to PLT20K (median/95%CI) | 34 (4–70) | 34 (27–134) | NS | | Proportion engrafting PLT | 69% | 55% | 0.2 | | 1-year survival | 60% (40–75) | 46% (27–63) | 0.2 | | 2-year survival | 55% | 20% | 0.1 | | aGVHD gd II–IV/III–IV | 43%/7% | 43%/17% | NS | | C.Incid. cGVHD | 45% (28–78) | 25% (15–65) | 0.1 | | C.Incid.: cumulative incidence | | |

Relapse has become the major cause of treatment failure after allogeneic stem cell transplantation. Outcome of patients with clinical relapse after transplantation generally remains poor, but intervention prior to florid relapse improves outcome for certain hematologic malignancies. To detect early relapse or minimal residual disease, sensitive methods such as molecular genetics, tumor specific molecular primers, fluorescence in situ hybridisation (FISH), and multiparameter flow cytometry (MFC) are commonly used after allogeneic stem cell transplantation to monitor patients, but not all of them are included in the commonly employed disease-specific response criteria. The highest sensitivity and specificity can be achieved by molecular monitoring of tumor- or patient-specific markers measured by polymerase chain reaction-based techniques, but not all diseases have such targets for monitoring. Similar high sensitivity can be achieved by determination of donor chimerism, but its specificity regarding detection of relapse is low and differs substantially among diseases. Here we summarize the current knowledge about the utilization of such sensitive monitoring techniques based on tumor specific markers and donor cell chimerism and how these methods might augment the standard definitions of post-transplant remission, persistence, progression, relapse and the prediction of relapse. Critically important is the need for standardization of the different residual disease techniques and to assess the clinical relevance of minimal residual disease and chimerism surveillance in individual diseases, which in turn must be followed by studies to assess the potential impact of specific interventional strategies.