ALBERT

Description: Abstract 255 Introduction: Standard treatment of acute myeloid leukemia (AML) comprises one or two cycles of chemotherapy to induce complete remission (CR) followed by postremission treatment in order to prevent relapse of the disease (consolidation therapy). In 2003, we initiated a prospective multicenter randomized trial to investigate the impact of different consolidation strategies on long-term outcome in AML patients ≤ 60 years. Consolidation options comprised upfront allogeneic stem cell transplantation (allo SCT) in aplasia after induction therapy, autologous SCT, and three cycles of standard high-dose-cytarabine-based consolidation. For patients receiving high-dose cytarabine, the main study aim was to evaluate the benefit of adding additional mitoxantrone and amsacrine to cytarabine consolidation. Design: From 2003 to 2009, 1182 patients (median age, 48 years; range 16–60 years) with untreated AML were randomly assigned at diagnosis to different consolidation strategies after classical 7+3 induction. According to the risk-adapted treatment strategy of the trial, cytogenetically or molecular intermediate-risk (IR) and adverse-risk (AR) patients should receive an allo SCT as consolidation treatment if an HLA-identical-sibling donor (IR) or HLA-matched related or unrelated donor (AR) was available. IR and AR patients with no available donor should receive autologous SCT. All favorable risk patients and patients with no available donor were scheduled for high-dose cytarabine based consolidation. Half of the patients were randomized for high dose cytarabine based consolidation. Half of the patients were randomized for high dose cytarabine alone while the other half received high dose cytarabine with the addition of amsacrine and mitoxantrone. Standard chemotherapy consisted of three cycles with high dose cytarabine (2 × 3 g/m2, day 1,3,5) whereas combined consolidation contained two cycles of MAC (cytarabine 2 × 1g/m2, day 1–6, mitoxantrone 10 mg/m2, day 4–6) plus one cycle of MAMAC (cytarabine 2 × 1 g/m2, day 1–5, amsacrine 100 mg/m2, day 1–5). In order to evaluate the effect of the two cytarabine based consolidation strategies, we determined overall survival (OS) and event free survival (EFS) using the method of Kaplan Meyer. Survival distributions were compared using the log rank test. Results: 1182 patients were randomized for further intervention (Arm A+B: n=582, 49.3%; Arm C+D: n=600, 50.7 %). Median follow-up was 41.4 months (95%-CI 39.3–43.6). A total number of 375 patients received allogeneic (n=322) or autologous SCT (n=53) and 807 patients were consolidated with cytarabine. Of these patients, 407 were randomized for cytarabine alone and 400were randomized to receive cytarabine plus mitoxantrone and amsacrine (MAC/MAC/MAMAC). Complete remission rate (CR) after second induction therapy was 59.1% (n=698). Between the four arms, there were no significant differences of the CR rates. Five-year OS of patients receiving high dose cytarabine alone was 47.1% (95%-CI 42.0–52.2%), for patients receiving MAC/MAMAC as consolidation therapy it was 46.8% (95%-CI 42.3–51.3%; p = 0.610). Three-year event free survival (EFS) was also not significant with 30.5% (95%-CI 26.6–34.4%) for patients receiving high dose cytarabine alone and 35.6% (95%-CI 31.7–39.5%; p = 0.059) for patients receiving MAC/MAMAC. Conclusions: According to our data, the addition of mitoxantrone and amsacrine to high dose cytarabine consolidation confers no benefit for treatment outcome in younger AML patients. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3459 The different intra- and extracellular constituents of the hematopoietic stem cell (HSC) niche in the human bone marrow are tightly regulated and of momentous importance for various properties of HSCs. Some of these are regulated through β1-Integrins (CD29) which therefore dramatically influence HSC and mesenchymal stromal cell (MSC) interaction in the niche. Important regulators within these cells are microRNAs (miRNAs). These small, non-coding RNAs control the expression of around two-thirds of the human protein-coding genes. One of these miRNAs, miR-134, previously referred to be a “brain-specific” miRNA was shown to be highly expressed in MSCs in tissue-studies conducted by our group. Since the central nervous system was recently shown to be closely connected to the regulation of HSCs and MSCs, we asked whether miR-134 which has several conserved binding seed-match sequences within the 3'UTR of β1-Integrin, regulates MSC mediated properties in the bone marrow niche. Screening of human MSC cell lines (n=4) by western blotting revealed highest β1-Integrin expression in SCP-1 cells. Transfection of SCP-1 with either siRNA directed against β1-Integrin (siCD29) or pre-miRNA-134 (pre134) revealed a downregulation of β1-Integrin at the mRNA level only in siRNA transfected cells, p=0.01. In contrast, at the protein level, as measured by western blot and FACS analysis, p=0.002, β1-Integrin was downregulated by siCD29 as well as by pre134, indicating a miRNA-specific action of repression. Confirmatory, the 3'UTR of β1-Integrin, which contains several putative binding sites for miR-134, was cloned into a pMiRReporter vector and luciferase activity was measured after cotransfection with pre134. The luciferase activity was significantly reduced in pre134 transfected cells [1.80 ± 0.46 (preCo) vs. 0.99 ± 0.49 (pre134); p

Description: Abstract 324 Introduction and classification: This is the largest adult T-ALL cohort treated according to immunologic subtypes. All patients were immunophenotyped in one central lab (Berlin). T-ALL (cyCD3+, CD7+) were subclassified into early T-ALL (sCD3-, CD1a-), thymic T-ALL (sCD3-/+, CD1a+) and mature T-ALL (sCD3+, CD1a-). T-ALL constitutes in 3 consecutive GMALL-studies 24% of ALL patients. Patients and methods: A total of 744 T-ALL pts (15 to 55 yrs) were accrued in 102 hospitals in the GMALL studies 05/93, 06/99 and 07/2003. In GMALL 05/93 239 adult T-ALL patients, were treated according to a multi-agent chemoprotocol. Stem cell transplantation (SCT) was not recommended in CR1. In GMALL studies 06/99 and 07/03 505 T-ALL pts received intensified chemotherapy; particularly with introduction of PEG-asparaginase in induction as well as HDMTX/PEG-Asp consolidation cycles. Based on study 05/93 results, SCT from sibling (Sib) as well as matched unrelated (MUD) donor in CR1 was recommended for all patients with early T-ALL, mature T-ALL and for high-risk (HR) pts with thymic T-ALL (defined as late CR, complex karyotype or MRD positivity (MRD+)). Results: T-ALL subtype distribution in the total cohort of 744 adult T-ALL was early-T 23% (N=170), thymic-T 56% (N=420), mature-T 21% (N=154), without any differences between the studies. GMALL Study 05/93: The overall CR rate was 86% (early-T 72%, thymic-T 93%, mature-T 84%. The lower CR rate in early T-ALL was mainly due to early death (19%). The overall CCR rate was 47% (early-T 45%, thymic-T 54%, mature-T 30%). The overall survival rate at 10 yrs for all pts was 47% (early-T 47%, thymic-T 55%, mature-T 25%). GMALL Study 06/99 and 07/03: Of the 505 patients, 87% achieved CR (early-T 84%, thymic-T 92%, mature-T 77%). PR/Failure was higher in early-T (13%) and mature-T (17%) compared to thymic-T (5%). Early death was 4% and equally distributed. 267 pts (64%) received chemotherapy only and the majority were 229 pts (86%) with thymic T-ALL, not considered for SCT in CR1. The CCR rate was 61%. The few early (n = 15) and mature (n = 23) T-ALL pts, which could not have a transplant in CR1, are a negative selection (e.g. early relapse, comorbidity, no donor) and their CCR rate was 33% and 22% respectively. This was due to a high relapse rate in early T-ALL (60%) and mature-T (74%) compared to 33% in thymic-T. Overall survival rate at 8 yrs for thymic T-ALL with chemotherapy was 68%, for the 77 adolescent pts (15 to 25 yrs) even 76%. Stem cell transplantation: 153 T-ALL pts in studies 06/99 and 07/03 received a SCT in first remission. SCT realisation rate in early T-ALL was 84%, in mature-T 68%. Overall CCR rate was 58% (early-T 47%, HR thymic-T 79%, mature-T 61%). Relapse rate after SCT was in early-T 33% and in mature-T 22%. The overall TRM rate was 18% despite more than half MUD SCT, without any TRM difference between the immunological subtypes. Overall survival rate after SCT in CR1 at 8 yrs was 53%, early-T 44%, thymic-T 67%, mature-T 59%. SCT modalit: 49% received alloSib, 55% alloMUD and 20% auto-SCT. Overall CCR rate after alloSib for the total cohort was 65% (early-T 60%, thymic-T 73% and mature-T 69%); for alloMUD total 55% (early-T 45%, thymic-T 77%, mature-T 61%) and for the small cohort of 20 pts with auto-SCT CCR was 35%. Conclusion: The strategy in three consecutive GMALL studies to stratify and treat adult T-ALL pts according to the immunologic T-subtypes was successful. Overall survival at 5 yrs could be improved to 56% from 44%. There was a particular improvement for mature T-ALL (49% vs. 30%) and early-T (40% vs. 33%). This was mainly due to a high realisation rate of SCT in early T-ALL and mature T-ALL and the substantial better results of SCT. Results of alloMUD SCT were comparable to alloSib SCT. The small cohort of HR thymic T-ALL pts also had a benefit from SCT. The excellent outcome of SR thymic T-ALL (∼ 50% of all T-ALL) with the OS of 68% and 76% in adolescents due to intensified chemo, partic. PEG-Asp, does not suggest SCT in CR1. Several molecular markers, such as ERG, BAALC, WT1, had in a retrospective analysis some prognostic relevance in this pt cohort. The new GMALL study generation will however focus in thymic T-ALL on early evaluation of MRD to decide for SCT (MRD+) or not (MRD-) whereas early/mature T-ALL remain allocated to high risk groups with SCT in CR1. Supported by Deutsche Krebshilfe 702657Ho2 and BMBF 01GI9971/8 Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4041 Hematopoietic stem cell transplantation is a commonly used treatment for various hematological malignancies. However, a life-threatening complication following this therapy is the development of Graft versus Host Disease (GvHD), during which transplanted donor immune cells attack the host and lead to severe inflammatory responses and tissue damage. Given the key role of regulatory T cells (Tregs) in immune homeostasis and peripheral tolerance, the adoptive transfer of these cells may represent a promising therapeutic opportunity for the treatment of GvHD. This approach has been proven successful to enhance graft acceptance and prevent experimental GvHD in several animal models. However, it becomes increasingly evident that antigen-specific Tregs are more efficient than polyclonal Treg populations. The antigen-specificity enables the cells to exert their suppressive effect locally at the appropriate sites of inflammation. Furthermore, the application of antigen-specific Tregs might lower the risk of unfavourable systemic immunosuppression. Nevertheless, one of the main obstacles for their clinical use is the isolation and expansion of therapeutically relevant numbers of antigen-specific Tregs. In light of these arguments, bispecific antibodies (bsAb) could provide a promising tool for a target-dependent tissue specific redirection of polyclonal Tregs. BsAb redirect T cells to target cells by cross-linking their activating CD3 receptor and any chosen antigen on the surface of the target cell. Several studies have proven that CD8+ and CD4+ effector T cells can be successfully activated by bsAb both in vitro and in vivo. However, so far nobody has ever investigated whether Tregs can be redirected with bsAb. Using bsAb against CD3 and two different target antigens we first examined the expression of different activation associated markers on CD4+CD25+ Tregs. We could show that incubation of Tregs with a bsAb in the presence of the respective target antigen leads to the upregulation of CD25, CD69 and LAP (figure 1). Furthermore, we analyzed the cytokine production profile of the bsAb-activated Tregs. Culturing the cells together with target cells and a cross-linking bsAb triggers the release of the immunomodulatory cytokine IL-10. One prerequisite for the treatment of graft rejection and GvHD with bsAb-redirected Tregs is their suppressive efficacy upon antigen-specific activation via bsAb. Therefore we monitored the ability of bsAb-redirected Tregs to inhibit effector mechanisms of autologous T helper cells. Corresponding experiments could demonstrate the striking capacity of redirected Tregs to suppress proliferation, CD25 upregulation and cytokine production of co-cultured effector T cells (figure 2).Figure 1:Expression of different activation associated markers on Tregs incubated without (−) or with a bsAb (+) and the respective target antigen.Figure 1:. Expression of different activation associated markers on Tregs incubated without (−) or with a bsAb (+) and the respective target antigen.Figure 2:A) CFSE-labeled effector T cells (Teff) were cultured together with either unlabeled autologous effector T cells or Tregs at effector:suppressor ratios of 1:1 or 4:1 in the presence (+) or absence (−) of a bsAb and the respective target antigen. B) Cytokine secretion of bsAb-activated Teff in the presence (white bars) or absence (black bars) of autologous bsAb-activated Tregs.Figure 2:. A) CFSE-labeled effector T cells (Teff) were cultured together with either unlabeled autologous effector T cells or Tregs at effector:suppressor ratios of 1:1 or 4:1 in the presence (+) or absence (−) of a bsAb and the respective target antigen. B) Cytokine secretion of bsAb-activated Teff in the presence (white bars) or absence (black bars) of autologous bsAb-activated Tregs. Taken together, we give evidence for the first time that bsAb can redirect Tregs against a surface antigen independently of their T cell receptor specificity. In view of these results, an antigen- and/or site-specific retargeting of Tregs using bsAb may open novel therapeutic approaches for a long-term establishment of tolerance against allogenic transplants and therefore would offer a new treatment option for severe GvHD after allogenic stem cell transplantation. Disclosures: No relevant conflicts of interest to declare.

Description: Beyond disease biology, the success of allogeneic hematopoietic stem cell transplantation (HSCT) in patients with hematological malignancies is mainly determined by the occurrence and extent of graft versus host disease (GVHD). Therefore, prevention of GVHD is the major goal and challenge in clinical HSCT. A calcineurin-inhibitor combined with methotrexate is the standard graft versus host disease (GVHD) prophylaxis after allogeneic hematopoietic stem cell transplantation (HSCT). Everolimus is a derivative of sirolimus, which also seems to mediate anti-leukemia effects. Given the potential synergism and favourable toxicity profile of everolimus and tacrolimus (EVTAC) after allogeneic HSCT we sought to investigate the efficacy of this combination in patients with either myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML). We report a combination of everolimus (days 0–56) and Tacrolimus (from day −1 on) in 24 patients (pts, median age 62 years) with either MDS (n=17) or AML (n=7) undergoing intensive busulfan-based conditioning followed by HSCT from related (n=4) or unrelated matched (n=12) or 1-allele mismatched (n=8) donors. All pts engrafted and only one experienced grade IV mucositis. However, although everolimus was scheduled to be administered up to day 56, patients received the drug a median of 44 days (range 10–56) only. The reason for premature discontinuation (50%) were either occurrence of early-onset (day 6) GVHD associated hyperbilirubinemia CTC grade 4 (n=1), transplantation-associated microangiopathy (TMA, n=3), sinusoidal obstructive syndrome (SOS) of the liver (n=6) or a drop of platelets after engraftment by at least 50% (n=2). Nine pts (37%) developed grade II–IV acute GVHD, however, chronic extensive GVHD was observed in 11 of 17 (64%) evaluable pts. TMA occurred in 7 pts (29%) with two cases of acute renal failure. In five out of seven patients with TMA either tacrolimus (n=4) or everolimus (n=1) blood through levels were slightly above the upper target level at the time of TMA appearance. The study was terminated prematurely because additional 6 pts (25%) developed SOS, which was fatal in two cases. With a median follow-up of 26 months, the 2-year overall survival rate is 47%. In conclusion, although this new combination appears to be effective as prophylactic regimen for acute GVHD, the incidence of TMA and SOS seems to be higher compared to other regimens. As a result this combination cannot be recommended as prophylactic regimen after busulfan-based intensive conditioning. However, studies in the context of TBI-based or reduced-intensity conditioning regimens might come to a different conclusion.

Description: Introduction: The majority of MDS patients become red blood cell transfusion-dependent during their clinical course. In fact, the presence or absence as well the extent of red blood cell transfusion-dependency (RBC-TD) has been recently shown to add significant prognostic information for an individual MDS patient treated with supportive care (BSC) only. Given the fact that allogeneic hematopoietic cell transplantation (HCT) is the only curative option for MDS patients, the aim of this study was to elucidate the role of RBC-TD on patient outcome. Methods: We report results of a retrospective multicenter German-Austrian study investigating 100 patients with MDS (RA(RS) n=33, RAEB n=33, RAEB-t n=19, CMMOL n=11, MDS/AML n=4) with either IPPS LOW (n=2), INT-1 (n=31), INT-2 (n=37) or HIGH (n=30) undergoing allogeneic myeloablative conditioning followed by peripheral blood stem cells (PBSC) from related (n=39) or unrelated donors (n=61). The median age of the patients was 50 years (range 18–68). Results: With a median follow-up of 32 months the 2-year overall survival (OS) was 48% for all patients and 64%, 50% and 34% for patients according to IPSS INT-1, INT-2 or HIGH, respectively (p=0.03 for INT-1 vs. HIGH). The 2-year OS of all patients was not different when comparing 68 patients displaying vs. 24 not displaying RBC-TD prior to PBSCT (46% vs. 55%, p=0.67). This holds also true when analyzing INT-1/INT-2 (n=62) as well as HIGH (n=27) patients separately. In a multivariate analysis only FAB classification (p=0.03) but not prior induction chemotherapy (n=18), presence of fibrosis (n=18), IPSS LOW/INT-1 vs. INT-2/HIGH, RBC-TD as well as ferritin level lower or above the median 973 μg/l (range 19–7000) had an impact on OS. Conclusion: These data suggest that the negative prognostic impact of RBC-TD in MDS patients receiving BSC can be overcome by myeloablative allogeneic PBSCT.

Description: Abstract 202 Introduction: In a completed study (NCT00337519), patients with advanced B-CLL received allogeneic stem cell transplantation (SCT) after cytoreductive treatment with alemtuzumab followed by a wash-out period for the antibody and conditioning with fludarabine/busulfan. Aim of the present investigation was to correlate flow cytometric levels of minimal residual disease (MRD) in the peripheral blood at different time points after transplantation with patient outcome. Patients and Methods: In 58 CLL patients 900 flow cytometric MRD investigations (at least 4 measurements/patient: at day 30, between days 31–100, 101–180, and 181–365 after SCT) were performed measuring the following CLL phenotype: CD19posCD5posCD20dimCD79bneg. Therefore, a 4-color-approach (FACSCalibur, until 2006) or an 8-color-approach then in combination with T- and NK cell antigens (FACSCanto) was performed. A patient was defined as MRD negative if less than 0.05% CLL cells were detectable or as relapse if more than 0.05% CLL cells were again redetectable in at least two successive investigations. For assessment of progression-free survival (PFS), clinical progress was defined according to the NCI criteria. Results: The median follow up time after SCT was 536 days (range: 44d –1758d). Considering all 58 transplanted patients the probability of one-year overall survival (OS) including the 95% confidence interval was 83% ± 10% (2-year OS: 76%±12%) and of one-year PFS 74% ± 12% (2-year PFS: 50%±16%). In the majority of cases flow cytometric MRD negativity was achieved within the first year post SCT with a cumulative incidence of 36%±13% at day 100 and of 73%±12% at one year, respectively. Only two additional patients became MRD negative within the second year post SCT. Patients who achieved MRD negativity until day 365 showed a significantly better 2-year OS compared to the MRD positive group (96%±7% vs. 56%±49%; p=0.009). Remarkably, the 2-year PFS of patients achieving flow cytometric MRD negativity until day 365 was also significantly better than in the MRD positive cases (83%±16% vs. 0%, 3-year: 75%±20% vs. 0%; p=0.002). Of note, early flow cytometric MRD negativity until day 100 was not informative concerning OS or PFS at one year (88%±13% vs. 79%±15% and 77%±18% vs. 72%±18%). The flow cytometric MRD status was one trigger to speed the taper of cyclosporine or to give DLI. Interestingly, this kind of immunomodulation resulted in flow cytometric MRD negativity in eight out of nine patients after a median of 130 days. The probability of relapse in the investigated patient cohort was 15%±10% after 1 year and 31%±14% after 2 years. Thus, 8/14 patients showed a clinical relapse in parallel with flow cytometric MRD positivity. Two patients featured an isolated flow relapse with MRD at two successive investigations. Four patients showed a mere nodal relapse, all but one occurring within the first year post SCT. Conclusion: In summary, the present flow cytometric MRD study in B-CLL patients elucidates the dynamics of remission induction and relapse in the first year post SCT. In the majority of patients MRD is eradicated between day +100 and day +365 which is the time interval when chronic GvHD occurs in most cases. Therefore, close monitoring of MRD status in the first year after SCT is necessary. Once patients are flow cytometrically MRD negative at day 365, they seem to have a high probability of long term survival. Disclosures: Schetelig: Schering-Bayer: Research Funding.

Description: In adult Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL), minimal residual disease (MRD) after stem cell transplantation (SCT) is associated with a relapse probability exceeding 90%. Starting imatinib in the setting of MRD may decrease this high relapse rate. In this prospective multicenter study, 27 Ph+ ALL patients received imatinib upon detection of MRD after SCT. Bcr-abl transcripts became undetectable in 14 (52%) of 27 patients, after a median of 1.5 months (0.9-3.7 months) (earlyCRmol). All patients who achieved an earlyCRmol remained in remission for the duration of imatinib treatment; 3 patients relapsed after imatinib was discontinued. Failure to achieve polymerase chain reaction (PCR) negativity shortly after starting imatinib predicted relapse, which occurred in 12 (92%) of 13 patients after a median of 3 months. Disease-free survival (DFS) in earlyCRmol patients is 91% ± 9% and 54% ± 21% after 12 and 24 months, respectively, compared with 8% ± 7% after 12 months in patients remaining MRD+ (P 〈 .001). In conclusion, approximately half of patients with Ph+ ALL receiving imatinib for MRD positivity after SCT experience prolonged DFS, which can be anticipated by the rapid achievement of a molecular complete remission (CR). Continued detection of bcr-abl transcripts after 2 to 3 months on imatinib identifies patients who will ultimately experience relapse and in whom additional or alternative antileukemic treatment should be initiated.

Description: Besides graft versus host disease (GVHD), disease relapse is one of the major challenges in the care of patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) undergoing allogeneic peripheral blood stem cell transplantation (PBSCT). However, we and others have shown that relapse can be predicted in case of CD34-expression on the malignant clone by a sensitive chimerism analysis in sorted CD34+ peripheral blood cells. If the percentage of donor cells in this compartment drops below 80%, leukemia relapse is inevitable within 4–8 weeks in the absence of clinical interventions like immediate cessation of immunosuppressive drugs or the administration of donor lymphocyte infusions. However, both approaches often result in clinically significant GVHD. Therefore, new strategies are warranted in order to treat imminent relapse in MDS or AML patients. We report results of an ongoing phase II clinical trial evaluating the efficacy of 5-azacitidine (5-aza) to prevent hematological relapse in patients with CD34+ AML or MDS and a decreasing CD34-donor chimerism after allogeneic PBSCT. Therefore, a total of 23 patients with CD34+ MDS (n=3) or AML (n=20) were prospectively screened on day 56, 84, 112, 140, 184, 365 and at later time points after PBSCT for a decreasing chimerism of donor CD34+ cells in the peripheral blood. In case of imminent relapse, defined as a drop of donor CD34+ cells below 80%, 5-aza was given at a dose of 75mg/m2/d s.c. day 1–7. A total of 4 cycles every 28 days were allowed in the absence of hematological relapse or toxicity. A median of 226 days after PBSCT, 9 out of 23 patients screened entered the treatment phase of the study with a median of 31% (range 0–53%) CD34+ donors cells in the peripheral blood (PB). However, a complete overall PB donor chimerism and less than 5% marrow blasts were documented in all patients before 5-aza treatment. Reversible neutropenia and thrombocytopenia grade 3/4 occurred in 50% of the patients. Only three patients still had immunosuppression prior 5-aza, which in two of them was slowly tapered during the period of 5-aza administration. With a median follow-up of 186 days after starting 5-aza all nine patients are eligible for response evaluation. Of these, CD34-chimerism was reverted to complete donor type (〉90%) in 6 (66%) patients. Two patients showed a further decrease of donor CD34+ cells and relapsed shortly after having completed the 1st or the 4th cycle of 5-aza, respectively. One patient showed an increase of CD34-chimerism after two cycles, however, died from non-relapse mortality. No hematological relapse occurred in the responders and in the screening cohort without decreasing CD34+ chimerism. Two patients (one without immunosuppression) developed limited cGVHD during 5-aza treatment. Preemptive treatment of minimal residual disease defined by decreasing donor CD34+ subset chimerism with 5-aza seems to be a potent strategy to prevent hematological relapse of CD34+ myeloid malignancies after allogeneic PBSCT.

Description: Haploidentical hematopoietic cell transplantation (HHCT) after high dose conditioning with a megadose of CD34-selected stem cells has been complicated by regimen related toxicities, slow engraftment and delayed immune reconstitution leading to high treatment related mortality (TRM). A new regimen using reduced intensity conditioning (RIC) and immunomagnetic CD3/CD19 graft depletion may allow HHCT with lower toxicity and faster engraftment. CD3/CD19 depleted grafts not only contain CD34+ stem cells but also graft-facilitating cells, CD34- progenitors, dendritic and natural killer cells which may allow stable engraftment even without a megadose of CD34+ cells. A multicenter phase I/II study of HHCT using RIC with fludarabine (150–200 mg/m2), thiotepa (10 mg/kg), melphalan (120 mg/m2), OKT-3 (5 mg/day, day -5 to +14) and CD3/CD19 graft depletion has been initiated. No post grafting immunosuppression was applied if the graft contained 500 granulocytes/μL of 12 days (range, 9–50) and to 〉20000 platelets/μL of 11 days (range, 7–38). Full donor chimerism was reached after 2–4 weeks in all but four patients (median of 14 days (range, 7–215)). Four patients experienced rejection/non-engraftment, two were rescued by a second CD3/CD19 depleted graft from another haploidentical donor. Incidence of grade II-IV acute GVHD was 51% with grade II=16, III=6 and IV=4. So far there are six cases of limited chronic GVHD and one case of extensive chronic GVHD. TRM in the first 100 days was 11/51 (22%) and overall 20/51 (39%). Overall survival is 17/51 patients (33%) with deaths due to relapse (n=14), infection (n=15), PML (n=2), GVHD (n=2) and cardiac failure (n=1), with a median follow-up of alive patients of 397 days (range, 62–1180). This results in a Kaplan-Meier estimate 1-year survival of 37%. So far, we did not observe a statistical significant survival advantage for patient transplanted from a KIR-mismatched donor (28/51 patients). This regimen with low toxicity as well as fast and sustained engraftment is promising in high risk patients lacking a suitable donor. To investigate the treatment protocol earlier in course of disease a new study for high-risk patients with acute leukemia in first complete remission is in preparation.