ALBERT

Description: Key Points Large-scale loss-of-function RNAi screens in patient-derived AML cells are feasible and able to pinpoint therapeutic targets. ROCK1 inhibition exerts antileukemic effects in primary human AML cells in vitro and in vivo.

Description: Application of autologous T cells genetically engineered to express CD19-specific chimeric antigen receptors (CAR-T) is highly effective in the treatment of B cell malignancies. To this date, application of CAR-T therapy beyond CD19 remains challenging due to the inability to control CAR-T reactivity in patients and the lack of tumor-associated antigens exclusively expressed by malignant cells. The interleukin-3 receptor alpha chain (CD123) is a promising immunotherapeutic target and associated with leukemia-initiating compartments in myeloid- or lymphoid derived diseases. However, in contrast to CD19, CD123 is a precarious target due to its prevalent expression on healthy hematopoietic stem and progenitor cells (HSPC) as well as endothelial cells. Thus, CAR-T lacking any fine-tuned control mechanisms are at risk to cause life threatening toxicities or can only act as bridging therapy to an allogeneic stem cell transplantation. To extend application of CAR-T therapy and safely redirect CAR-engineered T cells to challenging targets such as CD123, a switch-controllable universal CAR-T platform (UniCAR) was recently introduced. The UniCAR system consists of two components: (1) a non-reactive inducible second generation CAR with CD28/CD3ζ stimulation for an inert manipulation of T cells (UniCAR-T) and (2) soluble targeting modules (TM) enabling UniCAR-T reactivity in an antigen-specific manner. Here we provide late stage pre-clinical data for UniCAR-T in combination with a CD123-specific TM (TM123) for treatment of acute leukemia. Primary patient-derived CD123-positive leukemic blasts were efficiently eradicated by TM123-redirected clinical-grade manufactured UniCAR-T in vitro and in vivo. Activation, cytolytic responses and cytokine release were proven to be strictly switch-controlled. Moreover, anti-leukemic responses of UniCAR-T were demonstrated to be comparable to conventional CD123-specific CAR-T in vitro. In contrast to conventional CD123 CAR-T, TM123-redirected UniCAR-T discriminate between CD123high malignant cells and CD123low healthy cells with negligible toxicity towards HSPC in vivo. As 4-1BB mediated co-stimulation is known to enhance CAR-T activity in vivo, a novel CD123-specific targeting module bearing a covalently bound trimeric 4-1BB ligand (4-1BBL) was developed and characterized for co-stimulation at the leukemic site in trans. Specific binding of TM123-4-1BBL was demonstrated against native 4-1BB as well as CD123-positive leukemic blasts. In long-term tumor eradication models, TM123-4-1BBL ameliorated the killing capability of UniCAR-T in vitro. Additionally, the increased hydrodynamic radius of trimeric 4-1BBL-coupled TM123 prolonged plasma half-life and enhanced bioavailability in vivo. In conclusion, UniCAR-T maintain high anti-leukemic efficacy, while adding a sophisticated mechanism for immediate control to improve safety and versatility of CD123-directed CAR-T therapy. Moreover, switching between several TMs from short to moderate plasma half-life allows for an individualized treatment of various leukemic settings while minimizing potential adverse effects. Disclosures Loff: GEMoaB Monoclonals GmbH: Employment. Meyer:Cellex Patient Treatment GmbH: Employment. Dietrich:Cellex Patient Treatment GmbH: Employment. Spehr:Cellex Patient Treatment GmbH: Employment. Julia:Cellex Patient Treatment GmbH: Employment. Gründer:GEMoaB Monoclonals GmbH: Employment. Franke:GEMoaB Monoclonals GmbH: Employment. Bachmann:GEMoaB Monoclonals GmbH: Equity Ownership. Ehninger:Bayer: Research Funding; GEMoaB Monoclonals GmbH: Employment, Equity Ownership; Cellex Gesellschaft fuer Zellgewinnung mbH: Employment, Equity Ownership. Ehninger:GEMoaB Monoclonals GmbH: Employment, Equity Ownership; Cellex Gesellschaft fuer Zellgewinnung mbH: Equity Ownership. Cartellieri:Cellex Patient Treatment GmbH: Employment.

Description: The adoptive transfer of T cells engineered with chimeric antigen receptors (CARs) is currently considered as a highly promising therapeutic option for treatment of otherwise incurable malignant diseases. CARs combine the cellular and humoral arm of the immune response by assembling a single-chain fragment variable (scFv) as binding moiety which provides the antigen-specificity and an activating immune receptor. It has been demonstrated both in vitro and in vivo, that CAR engrafted effector T cells mediate long-lasting anti-tumor responses. Despite encouraging clinical efficacy targeting CD19 in recent clinical trials, the appearance of potentially life-threatening adverse reactions and the lack of control mechanisms once initiated, prevent more widespread application of the CAR technology. To overcome limitations of conventional CAR T cells, a unique chimeric antigen receptor (UniCAR) technology was developed (Fig. 1) which allows precise control of CAR T cell reactivity, thus lowering the risk of side effects while preserving efficacy. Moreover, the UniCAR technology enables the retargeting of engrafted T cells against more than one antigen simultaneously or subsequently, thus reducing the risk for development of antigen-loss tumor variants under treatment. The UniCAR technology splits the signaling and antigen-binding aspects of conventional CAR into two individual components. T cells are engineered to express a universal CAR (UniCAR), which has specificity for a short peptide motif of 10 amino acids derived from a human nuclear protein. Thus, T cells engineered to express UniCAR remain inactivated after re-infusion, since the UniCAR target is not available for binding under physiological conditions. The ultimate antigen-specificity of the system is provided separately by targeting modules (TMs) comprising a binding domain e.g., a tumor-antigen specific scFv, fused to the nuclear antigen motif recognized by the UniCAR binding domain. Here we provide first in vitro and in vivo prove of concept for this new approach. Antigen-specific redirection of T cells armed with the universal CAR in the presence of different targeting modules against various antigens (CD33, CD123, CD19, CD20, PSCA, PSMA,) was effective at femtomolar concentrations of the targeting module both. Taken together, the modular nature of UniCAR technology will allow retargeting of autologous, patient-derived T cells to several antigens under controlled pharmacological conditions and has the potential to become a highly effective treatment option for late stage cancer patients with reduced risks for side effects. Figure 1. Schematic representation of T cell recruitment with the modular UniCAR system. The UniCAR T cell recruitment system consists of two separated units. The first unit is the UniCAR expressed on T cells with a single-chain fragment variable (scFv) specific for a short 10 aa long peptide motif. The intracellular signalling domain of the UniCAR contains a costimulatory domain derived from CD28 and the T cell receptor z chain. The second unit is a targeting molecule (TM) which consists of a scFv fused to the peptide epitope. The cross-linkage of T cell and target cell is mediated by interaction between the UniCAR binding domain on T cells and target cell binding TM. Figure 1. Schematic representation of T cell recruitment with the modular UniCAR system. / The UniCAR T cell recruitment system consists of two separated units. The first unit is the UniCAR expressed on T cells with a single-chain fragment variable (scFv) specific for a short 10 aa long peptide motif. The intracellular signalling domain of the UniCAR contains a costimulatory domain derived from CD28 and the T cell receptor z chain. The second unit is a targeting molecule (TM) which consists of a scFv fused to the peptide epitope. The cross-linkage of T cell and target cell is mediated by interaction between the UniCAR binding domain on T cells and target cell binding TM. Disclosures Cartellieri: Cellex Patient Treatment GmbH: Employment. Loff:GEMoaB Monoclonals GmbH: Employment. Ehninger:GEMoaB Monoclonals GmbH: Employment, Patents & Royalties: related to the UniTARG system. Ehninger:GEMoaB Monoclonals GmbH: Equity Ownership; Cellex Patient Treatment GmbH: Equity Ownership. Bachmann:GEMoaB Monoclonals GmbH: Equity Ownership, Patents & Royalties: related to the UniTARG system.

Description: Based on compelling evidence from a vast number of in vitro and in vivostudies, Tregs have become an attractive cell population to treat or even prevent auto- and alloimmunity including Graft-versus-Host disease (GvHD). However, several safety concerns still exist as for example the risk of global immunosuppression using polyclonal Tregs. In fact, experiments in mice showed that adoptive transfer or induction of antigen-specific Tregs is more potent regarding suppression of pathogenic immune responses when compared to polyclonal Treg populations. Unfortunately, the isolation and expansion of naturally occurring antigen-specific Tregs is technically difficult, labour-intensive, and time-consuming. An attractive way to overcome these limitations and to endow polyclonal Treg populations with a desired antigen-specificity is their engraftment with chimeric antigen receptors (CARs). In this context, CAR-modification represents a promising approach to redirect polyclonal Tregs in an antigen-specific manner to suppress ongoing self-destructive immune responses at the site of inflammation. Nevertheless, until now redirection of CAR-engineered T cells is limited to a single target antigen, restricting this approach to an unflexible monospecific therapy. Therefore, we developed a more flexible universal CAR (UCAR) platform that allows redirection of T cells to an in principal unrestricted number of surface antigens. T cells are engrafted with UCARs that bind to a small peptide epitope derived from a human nuclear protein. Cross-linkage to target cells is mediated by independent target modules that provide antigen-specificity and comprise the peptide epitope recognized by the UCAR. In order to target different tissue antigens, the target modules can easily be exchanged. Thereby, once established, the treatment strategy can easily be applied to various auto- and alloimmune diseases. At present, the CD45RA+ population is the Treg subset of choice for a clinical application as these cells have the highest capacity to maintain phenotypic and functional Treg properties upon prolonged ex vivo expansion. Here we show that highly pure, sorted CD4+CD25+CD127lowCD45RA+ Tregs can be genetically manipulated using lentiviral gene transfer, resulting in approximately 70 % of UCAR-expressing Treg cells. The transduction procedure itself did not affect the phenotype of UCAR-engineered Tregs as it was similar to non-transduced wildtype cells. Both Treg populations presevered FOXP3 expression even after prolonged in vitro cultivation (〉 95 % FOXP3+). Upon incubation with antigen-positive target cells and a respective target module UCAR-engineered Tregs upregulate the activation markers CD69 and LAP demonstrating that the cells can be restimulated antigen-specifically. Most importantly, UCAR-engrafted Tregs were functionally activated upon antigen encounter, demonstrated by suppression of proliferation and expansion of cocultured autologous T effector cells. Taken together, our results pave the way towards an application of UCAR technology for a site-specific recruitment of CAR-modified Tregs into inflamed tissues aiming at re-establishing immune homeostasis. Due to its high flexibility UCAR-engrafted Tregs can easily and universally be used for treatment of various autoimmune diseases or GvHD just by exchanging the tissue-specific target modules. Disclosures Cartellieri: Cellex Patient Treatment GmbH: Employment. Ehninger:GEMoaB GmbH: Employment, Patents & Royalties. Ehninger:GEMoaB GmbH: Consultancy, Patents & Royalties. Bachmann:GEMoaB GmbH: Consultancy, Patents & Royalties.

Description: Abstract 144 Background: Sorafenib is a multi-kinase inhibitor with activity against several oncogenic kinases, which may play a role in the pathogenesis of acute myeloid leukemia (AML). In-vitro data and results from non-randomized clinical trials suggest that sorafenib might be an effective drug for the treatment of AML. So far, no randomized-controlled data are available for treatment of newly diagnosed AML patients up to the age of 60 years. We present the first results from the randomized placebo-controlled SORAML trial of the Study Alliance Leukemia (SAL). Patients and Methods: Between March 2009 and October 2011, 276 patients from 25 centers were enrolled in the SORAML trial (NCT00893373). The main eligibility criteria were: newly diagnosed AML, age from 18 to 60 years and suitability for intensive therapy. The treatment plan for all patients included two cycles of induction with DA (daunorubicin 60 mg/m2 days 3–5 plus cytarabine 100 mg/m2 cont. inf. days 1–7), followed by three cycles of high-dose cytarabine consolidation (3 g/m2 b.i.d. days 1, 3, 5). Patients without response after DA I received second induction with HAM (cytarabine 3 g/m2 b.i.d. days 1–3 plus mitoxantrone 10 mg/m2 days 3–5). Allogeneic stem cell transplantation was scheduled for all intermediate-risk patients in first complete remission with a family donor and for all high-risk patients with a matched donor. At study inclusion, patients were randomized to receive either sorafenib (800 mg/day) or placebo as add-on to standard treatment. Block randomization at a ratio of 1:1 was performed within cytogenetic and molecular risk strata, allocation was concealed and treatment was double blinded. Study medication was given on days 10–19 of DA I+II or HAM, from day 8 of each consolidation until 3 days before the start of the next consolidation and as maintenance for 12 months after the end of consolidation. The primary endpoint of the trial is event-free survival (EFS) with an event being defined as either failure to achieve a complete remission (CR) after induction, relapse or death. Secondary endpoints were overall survival (OS), CR rate and incidence of adverse events (AE). We present the results of the planned interim analysis (intent to treat) after the occurrence of 50% of EFS events. The O'Brien/Fleming adjusted significance level was set at p=0.0052. Results: Out of 276 randomized patients, 264 were evaluable for EFS, 132 in each arm. Demographic and disease characteristics were equally distributed between the two arms; the FLT3-ITD incidence was 16%. The median cumulative dose of administered study medication was equal in both arms. The CR rates were 56% versus 60% in the placebo versus sorafenib arm (p=0.622). By the time of analysis, a total number of 100 events had occurred. After a median observation time of 18 months, the median EFS was 12.2 months in the placebo arm and was not reached in the sorafenib arm, corresponding to a 1-year EFS of 50% versus 64% (p=0.023). The median OS had not been reached in both arms, the 2-year OS was 66% versus 72% in placebo and sorafenib arms, respectively (p=0.367). The most common reported AEs CTC Grade ≥3 were infectious complications including fever and pneumonia, followed by bleeding events, cardiac and hepatic toxicity, hypertension, skin toxicity and headache. The risk for hepatic toxicity (relative risk 6.2, p=0.025) and bleeding events (relative risk 3.6, p=0.016) was significantly higher in the sorafenib arm while the incidence of all other AEs showed no significant differences. Conclusions: In younger AML patients, the addition of sorafenib to standard chemotherapy is feasible but associated with a higher risk of liver toxicity and bleeding events. Sorafenib treatment resulted in a marked EFS prolongation; this difference is not significant according to the adjusted significance level of this interim analysis. Results from the final analysis including post-hoc exploration of molecularly defined subgroups are necessary for drawing final conclusions on the efficacy of sorafenib. Disclosures: Off Label Use: sorafenib for the treatment of acute myeloid leukemia. Serve:Bayer: Research Funding. Ehninger:Bayer: Research Funding.

Description: In patients with relapsed or refractory (r/r) Acute Myeloid Leukemia (AML), allogeneic Hematopoietic Stem Cell Transplantation (HSCT) is considered to be the only treatment providing long-term disease control for fit patients. The BRIDGE trial studied the safety and efficacy of a clofarabine-based salvage therapy prior to HSCT in patients with r/r AML. Here, we report the long-term follow up of this Phase II, multi-center, Intent-To-Transplant study and the impact of comorbidity on outcome. Eighty-four patients with a median age of 61 years (range 40 - 75) were enrolled. Patients were scheduled for at least one cycle of salvage therapy with CLARA (clofarabine 30 mg/m2 and cytarabine 1 g/m2, days 1-5). Chemo-responsive patients with a donor received HSCT after first CLARA. In the event of a prolonged donor search, HSCT was performed as soon as possible. The conditioning regimen consisted of clofarabine 30 mg/m2, day -6 to -3, and melphalan 140 mg/m2 on day -2. The ECOG score, hematopoietic cell transplantation-specific comorbidity index (HCT-CI) and Cumulative Illness Rating scale (CIRS) were obtained at study enrolment as well as prior to HSCT. Sixty-seven percent of the patients received HSCT within the trial. After a median follow up of 40months (95% CI, 38-49 months), the estimated 4-year OS (Figure 1) for all enrolled patients was 38% (95% CI, 28-50%) and Disease-Free Survival for transplanted patients was48% (95% CI, 36-64%). The CIR at four years was 30% (95% CI, 17-43%) and the NRM 22% (95% CI, 10-33%).Those patients who received an allogeneic HSCT within the trial had a median HCT-CI at the time of study enrollment of 1 (range, 0 - 6) compared to a median of 2 (range, 0 - 6) for those who did not proceed to allogeneic HSCT (p = .17). Corresponding figures for the CIRS were a median of 2 (range, 0 - 9) compared to 4 (range, 0 - 8) (p = .09). The median ECOG score was 1 (range, 0 - 3) in both groups. Compared to the time point of study enrollment, both the HCT-CI as well as the CIRS increased to a median of 2 (observed range of score, 0 - 7) and a median of 4 (observed range of score, 0 - 12), respectively, at the time of start of the conditioning regimen. This was almost exclusively due to an increase in infectious complications (Figure 2). Inmultivariate analysis, both the baseline HCT-CI and the ECOG score had a statistically significant impact with a HR of 1.22 (p = .025) and 1.72 (p = .001), respectively, on OS. Using a clofarabine-based salvage therapy combined with early allogeneic HSCT we were able to achieve good long-term results for patients with r/r AML. In this cohort, both the HCT-CI and the ECOG score gave prognostic information on OS, showing feasibility of comorbidity evaluation at the time of diagnose of r/r AML. Figure 1 OS of all enrolled patients Figure 1. OS of all enrolled patients Figure 2 Changes of the HCT-CI at baseline to HSCT Figure 2. Changes of the HCT-CI at baseline to HSCT Disclosures Middeke: Sanofi: Honoraria. Rösler:Janssen: Consultancy, Other: Travel/Accommodation/Expenses. Thiede:AgenDix: Employment, Other: Ownership. Schetelig:Sanofi: Honoraria.

Description: Abstract 1915 Bone marrow (BM) has been associated with a decreased rate of Graft-versus-Host-Disease (GvHD) when compared to peripheral blood stem cells (PBSC) in the context of allogeneic stem cell transplantation (allo-SCT). It has been reasoned that this may relate in part to the differential quantitative and qualitative immunologic composition of both stem cell sources. It has, for example, been noted that BM contains a higher percentage of CD8+ T-cells, natural killer (NK) cells and recently also more regulatory T-cells than PBSC. It is further known that the total nucleated cell concentration (TNC) correlates negatively with the BM harvest volume, which could argue for an increasing dilution of the transplant with peripheral blood (pB) during the BM harvest. How this impacts on the different immunological compartments and how the BM at different time points of the harvest procedure compares to PBSC products has not been determined yet. During routine BM harvest procedures (n = 24) we subjected a part of the aspirate drawn at the beginning, after withdrawing half of the prescribed volume and at the end of the harvest procedure to detailed immunophenotyping using multicolor flowcytometry including intracellular staining for FoxP3 and IL17. The PBSC products of an age matched group (n = 20) were analyzed in parallel with the same flowcytometry protocols and used as a comparison. During the BM harvest the median TNC dropped rapidly from 53.2 Gpt/l in the beginning to 17.0 Gpt/l after half the volume had been collected and finally reached 6.2 Gpt/l at the end of the procedure. As expected, the first BM specimen contained a higher concentration of NK- (6.7 vs. 4.6 %, p = 0.001) and B-cells (14.1 vs. 10.2 %, p 〈 0.001) but less T-helper-(Th)-cells (36.0 vs. 53.7 %, p 〈 0.001) than pB. After collection half of the prescribed volume the NK-cell concentration had already dropped to 4.5 %, which was not significantly different from pB (p = 0.412) anymore. The B-cell concentration, however, remained at levels comparable to the first specimen (14.5 %) and significantly differed from pB (p 〈 0.001). The last BM specimen drawn still had a higher B-cell concentration than pB (10.9 vs. 10.2 %), although this was not statistically significant (p = 0.265). Th-cells demonstrated a steady increase in concentration during the harvest with a median concentration of 43.4 and 47.0 % in the middle and at the end of the procedure. Both the halfway value and the end of harvest concentration were significantly different from pB (p 〈 0.001 and p = 0.004, respectively). An overview on the NK-, B- and Th-cell-concentrations at the different time points analyzed can be found in Figure 1. Within the Th compartment we were unable to see a clear trend for Treg which had a concentration of 7.6 % in the beginning, 7.0% halfway and 7.1 % after all BM had been collected. None of these concentrations was significantly different from that found in pB (7.6 %). The same applied to Th17 cells which made up 0.51 % of Th in the beginning, 0.59 % in the middle and 0.50 % at the end of the procedure and 0.84 % in the pB. Moreover there was no significant difference between the first BM specimen and PBSC products with respect to Treg (7.6 vs. 6.7 %, p = 0.181) or Th17 (0.51 vs. 0.61 %, p = 0.100). In contrast, the NK- and Th-cell concentration in PBSC products was significantly higher than in the first BM specimen (NK: 10.7 % vs. 6.7 %, p =0.005; Th: 40.3 % vs. 36.0 %, p =0.038). We conclude that the composition of immune cells within the BM changes significantly during the harvest procedure probably due to an increasing dilution with peripheral blood. These changes variably affect different compartments and may have an impact on post-transplant immunological function and complications. Therefore BM harvest volumes may need to be considered when comparing BM and PBSC with respect to clinical outcomes. In contrast to previous reports, we found no indication that BM, no matter at which time point analyzed, contained a higher concentration of Treg when compared to PBSC. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction The extent of systemic iron overload (SIO), quantified by magnetic resonance imaging (MRI), has been associated with adverse outcome in some studies in MDS and AML patients undergoing allogeneic stem cell transplantation (allo-SCT), whereas others were unable to demonstrate a significant impact. It has been hypothesized that the release of reactive iron species such as labile plasma iron (LPI) during the transplant procedure mediates iron-associated cellular toxicity by catalyzing the generation of oxygen radicals and fostering the growth of microbial agents. The association between SIO, the occurrence of LPI and the outcome after allo-SCT has not been prospectively studied so far. Patients, Material and Methods This was a Geman-Austrian prospective multicenter observational trial in 133 patients with AML or MDS undergoing allo-SCT between 2013 and 2015 (NCT01746147). Inclusion criteria were either having a ferritin above 500 ng/ml or having received more than 10 red blood cell concentrates. Liver iron content (LIC) was determined by MRI prior to and on day +100 and day +360 after allo-SCT. Enhanced labile plasma iron (eLPI) was measured using the Ferros eLPI Kit (Afferix) prior to, during and after conditioning and an eLPI above 0.4 was defined as positive. Results At the time of analysis 21 MDS and 90 AML patients were evaluable for LIC. The median age of the cohort was 61 years (range: 21 to 75 years) and the majority (80.2 %) received reduced intensity conditioning regimens. Median LIC prior to conditioning was 110 µmol/g and 45.9 % had a LIC above the pre-specified threshold of 125 µmol/g (7 mg/g) indicating SIO. A LIC 〉=125 µmol/g was associated with a significantly increased cumulative incidence (CI) of early (day +100) NRM (19.8 % vs. 6.8 % p = 0.034), thus confirming our previous observations (Wemke et al. ClinCancRes 2012). Prior to the initiation of the conditioning regimen positive eLPI levels were found in 26 of 109 evaluable patients. A significant correlation between LIC and pre-conditioning eLPI (Pearson's correlation coefficient: 0.470; p 〈 0.001) was noted. In fact, the median LIC in patients with a pre-conditioning eLPI 〉 0.4 was 190 µmol compared to 100 µmol/g in patients below this threshold (p 〈 0.001). Mean eLPI levels increased continuously during the course of the conditioning regimen and then gradually decreased starting on day +7, while most patients had negative eLPI levels by day +100 after allo-SCT (Figure 1). The presence of an eLPI above 0.4 prior to the initiation of the conditioning regimen was strongly associated with an increased early NRM (CI at day +100: 34.6 % vs. 6.0 % p 〈 0.001, Figure 2) and this association was confirmed in a multivariate analysis incorporating other factors known to predict for NRM (HR 7.0; 95% confidence interval: 2.076 to 23.91; p = 0.002). Of note, patients remaining LPI positive at day +14 also had a significantly increased NRM (19.0 % vs. 4.9 % p = 0.025), which also held true, when the analysis was restricted to patients being LPI negative prior to conditioning (12.5 % vs. 0.0 % p = 0.013). Patients having an eLPI above 0.4 prior to conditioning had a slightly higher CI of bacterial infections during the course of transplant (CI at day +100: 88.5 % vs. 83.3 %, p = 0.023). There was no association between a positive pre-conditioning eLPI and the occurrence of acute graft versus host disease of grade 2 or higher (CI: 39.1 % vs. 38.6 %). Conclusions The results of the prospective ALLIVE trial confirm recent single center observations that SIO prior to allo-SCT is associated with an increased mortality in AML and MDS patients. Given the fact that a positive eLPI prior to the initiation of the conditioning regimen and the persistence of positive eLPI levels after transplantation are strongly predictive for adverse outcome, it is reasonable to believe that reactive iron species are the key pathogenetic mediators in this context. Therefore, clinical trials assessing therapeutic interventions e.g. by peri-transplant iron chelation are warranted. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Wermke: Boehringer: Research Funding; Novartis: Research Funding. Bug:Celgene, Novartis: Research Funding; NordMedica, Boehringer Ingelheim, Gilead: Membership on an entity's Board of Directors or advisory committees; TEVA Oncology, Astellas: Other: Travel Grant. Theurl:Gilead Science: Research Funding. Platzbecker:Novartis: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Boehringer: Research Funding.

Description: Abstract 334 Background: The majority of patients diagnosed with Acute Myeloid Leukemia (AML) are older than 60 years. Although intensive induction chemotherapy is still the standard practice and a prerequisite for long-term survival, elderly patients have a higher risk of treatment related morbidity and lower remission rates than younger AML patients. An optimized induction treatment would combine high complete remission (CR) rates with tolerable toxicity. The combination of intermediate-dose cytarabine plus mitoxantrone (IMA) has recently been reported to result in high CR rates (73.5%) with acceptable toxicity in 86 elderly AML patients (Niederwieser et al., Blood 2002, abstr. 1337). We present the results of a randomized-controlled trial (RCT) comparing efficacy and tolerability of IMA with the standard 7+3 induction regimen consisting of daunorubicin plus cytarabine (DA). Patients and Method: In the 60plus trial of the Study Alliance Leukemia (SAL, former DSIL), AML patients 〉60 years considered medically fit for chemotherapy were randomized to receive either intermediate-dose cytarabine (1000 mg/m2 BID days 1,3,5,7) plus mitoxantrone (10 mg/m2 days 1–3) (IMA) or standard induction therapy with cytarabine (100 mg/m2 continuously days 1–7) plus daunorubicin (45 mg/m2 days 3–5) (DA). All patients who achieved a CR received cytarabine based consolidation treatment (2+5/MAMAC). Primary endpoint was the CR rate with an expected difference of 15% based on the results of the study named above. Secondary endpoints were the incidence of serious adverse events (SAEs), time to relapse (TTR), disease-free survival (DFS), and overall survival (OS). Result: A total of 492 patients with a median age of 69 years (range, 61–84) were enrolled between 2003 and 2009 by 29 German centers. 248 were randomized to receive IMA and 244 to receive DA. Patient characteristics were similar in the two treatment arms. In the intention-to-treat analysis, the CR rate was 59.3% (95% CI, 53.1–65.2) in the IMA arm and 51.2% (95%CI, 45.0–57.4) in the DA arm (p= 0.085). Mortality during the first 2 months after the start of study treatment was 18.1% and 18.4% in the IMA and the DA arm, respectively. Forty-five SAEs and grade-4 non hematological toxicities in 43 patients (19%) were reported in the IMA arm, while there were 57 SAEs in 52 patients in the DA arm (23%; p=0.1866). After a median follow-up time of 25.7 months (2.1 years), the median TTR is 10.3 months for IMA and 11.1 months for DA (p=0.328), the median DFS is 10.2 versus 11.7 months (p=0.11) and the median OS is 9.7 versus 10.8 months for IMA versus DA (p=0.945). This results in a 1-year OS of 43.6% in the IMA arm and 46.9% in the DA arm. Conclusion: Our current results show an equal efficacy and toxicity of both induction regimens. The trend for a higher CR rate after IMA does not translate into a survival advantage. Thus, our study indicates that elderly AML patients do not benefit from a dose escalation of cytarabine in induction therapy. Disclosures: No relevant conflicts of interest to declare.