Abstract: Background Double induction using two subsequent 7+3 regimens of cytarabine plus anthracycline is commonly performed in AML patients with an adequate performance status in order to maximize dose intensity upfront. However, for patients with a good early response at day 15 of first induction, there is no prospective randomized evidence on the necessity or value of a second induction cycle. Aims In order to answer the question if good responders of the first 7+3 induction could be spared a second induction cycle, we set up randomized-controlled SAL DaunoDouble trial. The study prospectively assesses the outcome of patients with a good early response with respect to the number of induction cycles (single versus double). We assumed non-inferiority of single induction in terms of complete remission (CR/CRi) rate, based on a margin of 7.5%. Here, we present the results of the planned interim analysis. Methods Patients (pts) 18-65 years with newly diagnosed AML, normal cardiac and organ function received a first induction cycle with seven days of cytarabine plus three days of daunorubicin ("7+3"). Response assessment in bone marrow was done on day 15 after the initiation of chemotherapy and confirmed by central review. A blast count & lt;5% was defined as good response. Pts with good response were randomized to receive a second induction cycle (arm D) or no second induction cycle (arm S). Primary endpoint was CR/CRi after completion of induction, secondary endpoints were RFS, and OS. Results Between 2014 and 2020, 624 evaluable pts were enrolled and received the first induction cycle with 7+3. A marrow blast clearance below 5% on day 15 was achieved in 298 pts (48%), providing eligibility for randomization. Of these patients, 150 were randomized into arm S and 148 into arm D, respectively. Median age was 52 years, 92% had de novo AML, NPM1 mutation was present in 53%, FLT3-ITD in 25% of pts. Favorable, intermediate and adverse risk (ELN 2017) were present in 56%, 34% and 10% of pts, respectively. CR/CRi rates at the end of induction were 86% after single induction and 85% after double induction. The CR/CRi rates in 224 pre-defined per-protocol pts were 88% versus 91%, resulting in a CR difference of 3% (95%-CI -0.047-0.111; p for non-inferiority test 0.145). After a median follow-up time of 24 months, RFS was slightly but not significantly lower after single induction with a 3-year RFS of 53% versus 64% (HR 1.4, p=0.125), whereas no differences were seen in 3-year OS, with a of rate of 74% versus 75% (HR 1.1, p=0.645) after single versus double induction. Conclusion The interim analysis results show that in good responders, the difference between CR rates after single versus double induction was even smaller than the predefined 7.5% margin, suggesting a trend for non-inferiority of single induction, although statistical significance was not reached. The trial continued recruitment. These findings suggest that in good responders, it may be safe to omit a second induction cycle if a second cycle poses a high risk. Figure. CR + CRi, RFS and OS after randomization to single versus double induction. Disclosures Alakel: Pfizer: Consultancy. Jost:Pfizer: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; JAZZ: Other: travel support; Celgene: Other: travel support. Novak:Roche: Consultancy; Janssen: Other: Travel expenses; Takeda: Consultancy; Amgen: Consultancy, Other: Travel expenses; Pfizer: Consultancy; Novartis: Consultancy. Krause:Takeda: Honoraria; Celgene: Other: Travel Support; MSD: Honoraria; Pfizer: Honoraria; Siemens: Research Funding; Gilead: Other: Travel Support. Held:Roche: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding; BMS: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding; MSD: Consultancy; Acrotech: Research Funding; Spectrum: Research Funding; Amgen: Research Funding. Platzbecker:AbbVie: Consultancy, Honoraria; Amgen: Honoraria, Research Funding; Geron: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria. Thiede:AgenDix GmbH: Other: Co-owner and CEO. Müller-Tidow:Daiichi Sankyo: Research Funding; Pfizer: Research Funding, Speakers Bureau; BiolineRx: Research Funding; Janssen-Cilag GmbH: Speakers Bureau.

Abstract: Background: Measurable residual disease (MRD) can identify patients (pts) with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) in complete hematological remission (CR) at high risk of relapse even after allogeneic hematopoietic stem cell transplantation (HSCT). We have recently shown in 53 pts treated within the first cohort of the RELAZA2 trial that pre-emptive therapy with azacitidine (AZA) at the time of MRD-positivity (MRDpos) can successfully prevent imminent hematological relapse (Platzbecker et al. Lancet Oncol. 2018). We now report on the results of the second cohort of 41 pts undergoing MRD-guided treatment in the RELAZA2 trial (ClinicalTrials.gov NCT01462578) by the Study Alliance Leukemia (SAL). Methods: Between 2015 and 2018, 166 MDS/AML pts were screened and centrally monitored for MRD in bone marrow or peripheral blood at monthly intervals for a period of 2 years prospectively in 9 centers in Germany. Of these 166, 41 pts with either advanced MDS (n=6) or AML (n=35) in CR after either conventional chemotherapy only (n=13) or consecutive allogeneic HSCT (n=28) developed MRD above a threshold defining imminent hematological relapse. Still being in morphological CR, these pts pre-emptively received 6 cycles of AZA (75mg/m2, s.c. days 1-7), which was followed by a risk-adapted AZA-maintenance therapy based on MRD-response for up to 18 additional months. Pts developing a hematological relapse went off study. MRD was detected by either the quantification of NPM1 mutation level (n=19), leukemia-specific fusion genes DEK-NUP214 (n=1) or RUNX1/RUNX1T1 (n=2) or a sensitive donor chimerism analysis of sorted CD34(+)/CD117(+) peripheral blood cells (n=28) in pts undergoing allogeneic HSCT. Here, we report the analysis of the primary endpoint of the 41 pts in the second cohort as well as the data for the entire 94 pts who entered the treatment phase of the RELAZA-2 study. Results: At a median of 110 days (range 28-476) after start of screening, 41 (25%) out of 166 prospectively screened pts became MRDpos as defined by either a decrease of CD34(+)/CD117(+) donor chimerism to & lt;80% (n=23) or a detectable mutation level & gt;1% (NPM1 n=18) while being still in hematological CR. All of these MRDpos pts started AZA-based pre-emptive treatment to prevent imminent hematological relapse. Six months after start of MRD-guided therapy, 25 out of 41 pts were still in CR (61%, 95%-CI 45-76%, p & lt;0.001, one-sided binomial test for H0: pexp≤0.3) while a total of 15 pts (37%) developed hematologic relapse after median of 3 AZA cycles. In fact, 19 pts (46%) responded with either a decline of MRD below a predefined threshold (increasing CD34(+) donor chimerism to ≥80% or mutation level & lt;1%), while a stabilization in the absence of relapse was achieved in 6 pts (15%). Overall response rate was not statistically different between pts with (57%) or without (69%) antecedent allogeneic HSCT (p=0.5). After 6 months of initiation of MRD-guided treatment, 21 pts (51%) continued to receive a median of 6 (range 1-15) subsequent AZA cycles. Eventually, hematologic relapse occurred in 6 of those pts (29%), but was delayed until a median of 320 days (range 219-375 days) after initial MRD detection. With a median follow-up of 9 months after start of MRD-guided pre-emptive treatment the 12-months overall and progression free survival rate is 94% and 44%, respectively. When combining results for the primary endpoint with the first cohort, the 6 months relapse free survival for all 94 pts was 60% (56/94 pts.; 49-70%; p & lt;.001 one-sided binomial test for H0: pexp≤0.3; Fig. 1). Conclusion: These multicenter prospective data provide further strong evidence that continuous MRD monitoring is feasible and can identify MDS/AML pts at high risk of hematological relapse. Pre-emptive MRD-guided therapy with AZA is an effective treatment to prevent or at least substantially delay hematologic relapse in these pts. Disclosures Platzbecker: Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Wolf:Celgene: Honoraria, Research Funding; Abbvie: Honoraria. Krämer:Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding. Bug:Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Jazz Pharmaceuticals: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel grants; Hexal: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sanofi: Other: travel grants; Celgene Neovii: Other: travel grant. Götze:AbbVie: Membership on an entity's Board of Directors or advisory committees. Stelljes:Novartis: Honoraria; Amgen: Honoraria; Jazz Pharmaceuticals: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; MDS: Consultancy. Subklewe:AMGEN: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Miltenyi: Research Funding; Oxford Biotherapeutics: Research Funding; Janssen: Consultancy; Roche: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Morphosys: Research Funding. Hänel:Celgene: Other: advisory board; Novartis: Honoraria; Takeda: Other: advisory board; Amgen: Honoraria; Roche: Honoraria. Dührsen:Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Alexion: Honoraria; Takeda: Consultancy, Honoraria; Teva: Honoraria; Celgene: Research Funding; Roche: Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Janssen: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; CPT: Consultancy, Honoraria. Müller-Tidow:MSD: Membership on an entity's Board of Directors or advisory committees. Thiede:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; AgenDix GmbH: Employment, Equity Ownership.

Abstract: In relapsed or refractory acute myeloid leukemia (AML) long-term disease-free survival may only be achieved with allogeneic stem cell transplantation (HSCT). However, only about 40% of patients (pts) with relapsed AML receive HSCT. A number of factors contribute to this low rate, among them, a moderate activity of currently available salvage regimens and accumulating toxicity of chemotherapy. Clofarabine is considered to have a favorable risk-benefit ratio in this indication and has been successfully used in conditioning regimens. Our goal was to study the safety and efficacy of a clofarabine salvage therapy as a bridge to HSCT. Here, we report the results of the BRIDGE trial (NCT 01295307), a phase II, multicenter, intent-to-transplant study. Patients and Methods Between March 2011 and May 2013, 84 pts with relapsed or refractory AML older than 40 years were enrolled. Pts were scheduled for at least one cycle of induction therapy with CLARA (clofarabine 30 mg/m2 and cytarabine 1 g/m2 days 1-5). Pts with a donor received HSCT in aplasia after first CLARA. In case 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. In pts with partially matched unrelated donors ATG (Genzyme) at a cumulative dose of 4.5 mg/kg was recommended. GvHD prophylaxis consisted of CsA and mycophenolate mofetil. Results Median age was 61 years (range 40 – 75). Forty-four pts suffered from relapsed AML and 40 pts had refractory disease. According to the current ELN risk stratification 17% of pts were classified as favorable risk, 35% as interm. I, 17% as interm. II and 20% as adverse risk. Complex and monosomal karyotypes were present in only 12% and 10% of pts, respectively. FLT3, NPM1 and CEPBA mutations were found in 16%, 24%, and 4% of the pts. The mean value of the HCT-CI score was 1.6 (range 0 - 7) at the time of study enrollment and 2.3 (range 0 - 7) at the time of conditioning. The overall response rate assessed at day 15 after start of CLARA was 80% (46% good response defined as less than 10% blast in the bone marrow (BM) and 33% moderate response with at least a marked reduction in BM blasts or BM cellularity and absence of blast in the peripheral blood). Seventeen pts did not respond to CLARA and were subsequently treated off study. Due to early death, three pts were not evaluable for treatment response. Overall, 66% of the pts received HSCT within the trial. Donors were HLA-identical siblings in eight pts (14%), HLA-compatible unrelated donors in 30 pts (55%) and unrelated donors with one mismatch in 17 pts (31%). Treatment success defined as complete remission, CR with incomplete recovery or 〉 95% BM donor chimerism and an absolute neutrophil count 〉 0.5 /nL on day 35 after HSCT was achieved in 62% of the pts. Disease-free survival (DFS) is shown in Figure 1. With a median follow up of 16 months the OS for all enrolled patients at one year is 51% (95% CI, 39% to 63%). At the time of enrollment, 14% had a related donor and 33% had an unrelated donor. In 46% of the pts donor search was initiated at the time of enrollment. For 7% of pts donor search was not successful. Time from study entry to HSCT was remarkably low with a median of 33 days (range 19 – 116 days). Of note, time interval did not differ between related and unrelated donors (Figure 2). Day 30 and day 100 mortality, which covered salvage therapy and HSCT, was 9% and 27%, respectively. Six out of seven pts who died within the first 30 days hat refractory AML and thus entered the trial already with a history of long-lasting neutropenia. Liver toxicity was the most frequent adverse event. Fifty percent of the pts had transiently elevated liver enzymes CTCAE grade III considered to be related to clofarabine. Twenty-one patients developed CTCAE grade III – IV sepsis throughout the study treatment. GvHD grade II – IV and III-IV until day 100 after HSCT occurred in 36% and 21% of the pts, respectively. Conclusions This intent-to transplant study allows for a realistic estimate for the outcome of elderly pts with relapsed or refractory AML. We demonstrate a high rate of leukemia-control by CLARA. Fast unrelated donor search and work up and conditioning with clofarabine and melphalan in aplasia allowed for a high rate of successful HSCTs. While the long-term results require longer follow-up the overall results are promising. Disclosures: Middeke: Genzyme: Speakers Bureau. Schetelig:Genzyme: Research Funding. Off Label Use: Clofarabine, not approved for AML.

Abstract: 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.

Abstract: Background: Most patients (pts) diagnosed with Acute Myeloid Leukemia (AML) are older than 60 years. Although intensive induction chemotherapy in medically fit pts is still the standard practice and a prerequisite for long-term survival, elderly pts have a higher risk of treatment related morbidity and lower remission rates than younger AML pts. An optimized induction treatment would combine high complete remission (CR) rates with tolerable toxicity. The combination of intermediate-dose cytarabine plus mitoxantrone (IMA) has been reported to result in high CR rates (73.5%) with acceptable toxicity in 86 elderly AML pts (Niederwieser et al., Blood 2002, abstr. 1337). We present the mature final results of a randomized-controlled trial comparing efficacy and tolerability of IMA with the standard 7+3 induction regimen consisting of daunorubicin plus cytarabine (DA). Patients and Methods: In the 60+ trial of the Study Alliance Leukemia (SAL), AML pts 〉 60 years and 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 pts in CR after DA received intermediate-dose cytarabine plus amsacrine (MAMAC) as consolidation treatment, whereas pts in CR after IMA were consolidated with standard-dose cytarabine plus mitoxantrone (2+5). Primary study endpoint was the CR rate with an expected difference of 15% in favor of IMA. Secondary endpoints were the incidence of serious adverse events (SAEs), time to relapse (TTR), relapse-free survival (RFS), and overall survival (OS). Results: Between February 2005 and October 2009, 852 pts were screened for study inclusion and 485 pts started study treatment, of which 241 pts were randomized for treatment arm A (DA) and 244 for treatment arm B (IMA). The median age was 69 years. Pt characteristics were equally distributed between the two arms. According to a strict definition, all patients with early death, study drop-out, or failed remission assessment were categorized as being not in CR. The CR rate amongst all 485 pts treated in the study was 47%. The CR rate after DA was 39% (95%-CI; 33-45) versus 55% (95%-CI; 49-61) after IMA (OR 1.89, p=0.001). If all first CRs were taken into account including those achieved after trial discontinuation, the CR rates after DA versus IMA induction were 55% versus 64% (p=0.043). Separate analyses addressing age, cytogenetics, de novo AML, NPM1 and FLT3-ITD confirmed higher CR rates after IMA induction throughout these subgroups. Six-week mortality was 14% in both arms. The median duration of ≥ grade 3 neutropenia was 23 days after DA I and 25 days after IMA (p=0.031). The median duration of thrombocytopenia ≥ grade 3 was 16 versus 20 days after DA I and IMA I, respectively (p 〈 0.001). The incidences of non-hematologic toxicities were not significantly different except for a higher incidence of liver toxicity (odds ratio IMA/DA = 0.52; p=0.001) and gastrointestinal symptoms (OR IMA/DA = 0.62; p=0.041) after DA. In the course of treatment, 11 pts in each arm (5%) received allogeneic stem cell transplantation. After a median follow-up of 66 months, RFS curves are superimposable in the first year with a similar median RFS of 11 months and 10 months after DA and IMA, respectively. However, a separation of RFS curves developed with longer follow up, resulting in 1-year RFS rates of 45% versus 46%, but 3-year RFS rates of 29% versus 14% in the DA versus IMA arms, respectively (p=0.042). The median OS for all randomized pts was 10 months in both arms; 1-year and 3-year OS rates were 45% and 19% after DA versus 44% and 19% after IMA (p=0.513). Conclusion: The results indicate that elderly AML pts benefit from a dose escalation of cytarabine in induction therapy by significantly higher CR rates and similar toxicity compared to a standard 7+3 approach. In our trial, this did not translate into a survival advantage, most likely due to differences in consolidation treatment of the respective treatment arms. In combination with an effective consolidation strategy such as high-dose cytarabine or allogeneic transplantation, our current results favor the use of intermediate dose cytarabine in induction for pts with a curative AML treatment approach. Figure 1. CR rates depending on induction treatment Figure 1. CR rates depending on induction treatment Disclosures Einsele: Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen/Onyx: Consultancy, Honoraria, Speakers Bureau. Thiede:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AgenDix GmBH: Equity Ownership. Platzbecker:Amgen, Inc.: Honoraria; GlaxoSmithKline: Honoraria, Research Funding; Celgene: Honoraria; Novartis: Honoraria. Ehninger:Cellex GmbH: Equity Ownership.

Abstract: The prognosis of AML in patients (pts) 〉 60 years (y) is poor and there is no universally accepted standard approach. After induction chemotherapy (IC), a complete remission (CR+CRi) rate of 56.4% and a mortality of 21% at day (d) 90 are expected (Niederwieser et al, ASH 2012). Azacitidine (AZA) yields a one-year survival (OS) rate of 46.5% in pts 〉 65 y and 〉 30% marrow (BM) blasts (Dombret et al, Blood 2015). Yet, AZA and IC are not mutually exclusive. First results of the interim analysis of the DRKS00004519 (RAS-AZIC) study which evaluates priming with AZA followed by AZA or IC in pts 〉 60 y with AML are presented. Patients and methods: Major inclusion criteria are newly diagnosed AML with marrow blasts 〉 20% by aspiration or biopsy irrespective of WBC count, age 〉 60 y, and eligibility for IC. Secondary AML from an antecedent hematologic disorder and therapy-related AML are not excluded. In the phase I part of the trial, safety of priming with AZA (75 mg/m2/day s.c) for 7 d followed by IC (Mitoxantrone 10 mg/ m2/day d 1-3 and cytarabine 1 g/m2/BID d 1, 3, 5, 7) on d 17 was established through a 3+3 design. In the multicenter phase II part (figure), priming was sequentially followed by AZA or IC based on d 15 BM blasts and d 56 response which were identified as early predictors for long-term response to AZA in AML (Al-Ali et al., Leuk Lymph 2012). The primary objective is overall response (OR) which includes CR, CRi, and PR at d 90 according to the International Working Group criteria (Cheson et al, J Clin Oncol 2003). Safety, OS, and mortality were secondary end points. According to the optimal two-stage design (Simon, Control Clin Trials 1989), an expected OR of 61% at the end of trial was estimated. Thus in a first stage analysis, 〈 19 of consecutive 40 (47.5%) pts not achieving the primary objective would be considered an indication for inferiority of the protocol treatment compared to standard IC. Hence, an interim analysis of the first stage was planned per protocol while accrual continues to include the first 40 pts who received the maximal tolerated priming dose of AZA. The trial is supervised by an independent Data Monitoring Committee. Adverse events (AEs) are reported according to the NCI CTCAE 4.03. All pts gave written informed consent. Results: Patient characteristics are shown in table 1. Median age is 69 y and median blast count 39%. All pts received priming with AZA. Median BM blasts at d 15 was 27% (range 2.4-88%). To date, data on subsequent therapies are captured in 33 (82.5%) pts. Except for one (withdrew consent on d 27), all pts received protocol assigned treatment based on BM blasts on d 15 [17/32 (53%) continued with AZA, 15/32 (47%) received IC]. Likewise, 26/32 (81%) pts ([2x data not yet available, 2x death (d 34; d 53), and 2x physician's choice] received response-adapted treatment on d 56 [12/26 (46%) started AZA maintenance and 14/26 (55%) received IC]. OR at d 90 for the 26 as yet evaluable pts is 80.7% [CR (61.5%, n=16); CRi (11.5%, n=3); PR (7.7%, n=2). No additional mortality till d 90 was reported. For the entire cohort, 85% of pts are alive after a median follow-up of 6 months. AEs were consistent with the known safety profile of AZA and IC. AEs 〉 grade 3 were reported 83x in 20 (50%) pts being mainly infectious and respiratory complications (60%). As expected, the majority (57%) were reported under IC, followed by 19% and 17% under priming and the 2. AZA cycle respectively. AEs led to postponement of the planned therapy in 6 pts (3x IC on d 17, 2x 2. AZA, 1x IC on d 56). The final assessment of the interim analysis is set in the near future. Conclusions: These data imply that in a heterogeneous disease like AML, integrating epigenetic therapy with chemotherapy in elderly pts in an individualized response-based approach is feasible, induces responses at least comparable to those seen after IC, and is associated with a remarkable low mortality. The definitive response rate and the impact of such an approach on survival will be answered at the end of the trial. Table 1. Patient characteristics (n=40) Median age, range (years) 69 ( 61 - 82) Male/Female (%) 55 / 45 Baseline ECOG (%)0/1/2 21 / 63 / 16 Type of AMLDo novo/secondary (%) 61 /39 Median WBC (range) x 109/L 6.7 (0.7 - 81.8 ) Median bone marrow blasts (aspiration) (range) (%) 39 (13 - 90) Cytogenetics (n=35)Normal/intermediate/unfavourable (%) 54 /23 / 23 FLT3+ (n=34) (%) 9 NPM1 + (n=34) (%) 9 Figure 1. Figure 1. Disclosures Al-Ali: Novartis: Consultancy, Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Off Label Use: Azacitidine is not approved for the use in patients with AML and blasts 〉 30% outside clinical trials.

Abstract: 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.

Abstract: Purpose: This multicenter study investigated the efficacy and safety of high-dose methotrexate (HD-MTX) induction followed by high-dose busulfan/thiotepa with autologous stem-cell transplantation (HD-BuTT) and response-adapted whole-brain radiotherapy (WBRT) in patients with newly diagnosed primary CNS lymphoma. Patients and methods: 23 patients (median age 55 years) were treated in five centres. Patients received HD-MTX (4h-infusion; 8g/m2; & gt;60y: 6g/m2) on d1 and d10 followed by leucapheresis. Then patients were stratified according to their results on neuroimaging: In case of at least a partial response, HD-BuTT consisting of 16mg busulfan / 10mg thiotepa per kg body weight followed by peripheral stem cell transplantation was given. Patients without response to induction or without complete response after high-dose therapy received WBRT (45Gy) as further treatment. Results: 16 patients received the planned treatment with HD-MTX followed by HD-BuTT. CR / PR rates for these patients were 19 % / 69 % after HD-MTX, 69 % / 13 % after HD-BuTT, 81 % / 6 % after HD-BuTT plus WBRT, respectively. Included the patients with early WBRT due to toxicity (n=2) and non-responders to HD-MTX induction (n=4) the overall response rate for all 23 patients was 83 % (intention-to-treat). Outcome was significantly influenced by the response to MTX-induction. There were three treatment-related deaths. Irradiated patients (n=9) had a high incidence of severe neurotoxicity leading to death in 3 patients. At a median follow-up of 15 months the median EFS and OS for all patients were 17 and 20 months, after HD-BuTT 27 months and “not reached”, respectively. Patients older than 60 years and younger patients have achieved similar outcomes. Conclusion: This study showed that HD-methotrexate induction followed by HD-BuTT is a feasible treatment option for newly diagnosed primary CNS lymphoma. Patients achieving CR after HD-BuTT show no signs of clinical neurotoxicity with median survival not reached yet. Time on treatment is 2–3 months only, but the induction treatment needs improvement to be more effective. WBRT in this study was associated with a high incidence of severe neurotoxicity and should therefore be avoided.

Abstract: Background: Monitoring of measurable residual disease (MRD) in patients (pts) with advanced myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) who achieve complete remission (CR) can predict hematological relapse. Recently published data from the first cohort of the RELAZA2-trial have shown that pre-emptive therapy with azacitidine (AZA) can prevent or substantially delay an overt relapse in MRD-positive pts with MDS or AML (Platzbecker et al. Lancet Oncol. 2018). Aims: To evaluate outcome of the entire patient cohort of the RELAZA2-trial and determine whether MRD-guided pre-emptive AZA treatment could prevent relapse in molecularly defined cohorts. Methods: Between 12/2011 and 07/2018 380 pts with advanced MDS or AML, who had achieved CR after conventional chemotherapy or allogeneic hematopoietic stem-cell transplantation (allo-HCT) were prospectively screened for MRD in monthly intervals either in bone marrow (BM) or peripheral blood (PB). A total of 94 pts (AML, n=83; MDS, n=11) became MRD positive during 24 months from baseline by either quantitative PCR (qPCR) or analysis of CD34+ donor-chimerism and entered the treatment phase. Preemptive MRD-triggered treatment consisted of AZA 75 mg/m2 per day subcutaneously on days 1-7 of a 29-day cycle for up to 24 cycles. After six cycles, MRD status was reassessed and pts with MRD negativity were eligible for treatment de-escalation. Primary endpoint was relapse-free survival (RFS) six months after start of pre-emptive treatment. For mutational analysis next generation sequencing (NGS) with a panel of 54 genes was performed (Illumina Trusight Myeloid). Results: Median age was 60 yrs (range: 22-80 yrs); 52 (55%) of the pts were female. Prior therapy consisted of chemotherapy in 42 (45%) and allo-HCT in 52 (55%) of the pts. Cytogenetics could be analyzed in 93 (99%) of the 94 pts. Risk categorization according to ELN 2017 was favorable in 30 (37%), intermediate in 31 (38%) and adverse in 21 (26%) of the AML pts, respectively. Type of MDS was advanced in all 11 pts and all were previously transplanted. Fifty-two (61%) of 85 pts with available NPM1 status were positive. NGS on 64 (68%) pts with available DNA at the time of first diagnosis revealed additional mutations in DNMT3A (n=25), TET2 (n=15), FLT3-ITD (n=12), IDH1 (n=9), FLT3-TKD (n=8), ASXL1, NRAS, TP53 (n=7, each), IDH2 (n=6), PTPN11, WT1 (n=5, each), GATA2, U2AF1 (n=4, each), CBL (n=3), CEBPA, CSFR3, CUX1, EZH2, KIT, RAD21, RUNX1, SF3B, STAG2, ZRSR2 (n=2, each), and KRAS (n=1). MRD data were correlated with outcome in 45 pts for NPM1, in 3 for RUNX1-RUNX1T1, whereas CD34-donor-chimerism was analyzed in 39 pts (missing, n=7). There was a significant faster and deeper decline of MRD in PB as compared to BM (P=0.03). The same held true with regard to the increase of donor-chimerism, which was achieved faster in PB as compared to BM (P=0.05). Secondary molecular abnormalities (MAs) had no impact on MRD response as measured by qPCR, which was also true if MAs were categorized functionally. Similarly, additional chromosomal abnormalities had no impact on MRD response in both MRD methods. However, in pts with measurement of donor-chimerism ASXL1 mutations were a negative factor for MRD response (P & lt;0.001). At hematological relapse, only 1 (2%) of 45 pts with NPM1 measurement was not congruently MRD positive. Six months after start of MRD-guided therapy, 56 (60%) of 94 pts were still in CR while a total of 38 pts (40%) developed a hematological relapse after median of 3 AZA cycles. 38 (40%) pts responded with either a decline of MRD below a predefined threshold (increasing donor-chimerism to ≥80% or PCR MRD & lt;1%), while a stabilization in the absence of relapse was achieved in 18 (19%) pts. Overall response rate was not statistically different between pts with (63%) or without (55%) antecedent allo-HCT (P=0.5). RFS rate at 6 months was 60% (56/94 pts). With a median follow-up of 9 months after start of MRD-guided pre-emptive treatment 12-months overall and progression-free survival rates were 94% and 44%, respectively. Conclusions: AZA as a pre-emptive therapy was effective in delaying hematological relapse of advanced MDS or AML pts, regardless of the underlying genetic signature. Based on these encouraging results, intensifying treatment with AZA in combination with pembrolizumab is currently investigated as MRD-guided treatment in NPM1 positive AML (PEMAZA; ClinicalTrials.gov Identifier: NCT03769532). Disclosures Wolf: Celgene: Honoraria, Research Funding. Bug:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hexal: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Eurocept: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel; Jazz: Honoraria; Neovii: Other: Travel; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel; Sanofi: Other: Travel. Götze:Celgene: Research Funding. Stelljes:Amgen: Consultancy, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau. Subklewe:Celgene: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Seattle Genetics: Research Funding; Morphosys: Research Funding; Janssen: Consultancy; AMGEN: Consultancy, Honoraria, Research Funding; Roche AG: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Gilead Sciences: Consultancy, Honoraria, Research Funding. Haenel:Amgen, Novartis, Roche, Celgene, Takeda, Bayer: Honoraria. Rollig:Amgen, Astellas, BMS, Daiichi Sankyo, Janssen, Roche: Consultancy; Abbvie, Novartis, Pfizer: Consultancy, Research Funding. Müller-Tidow:Pfizer: Research Funding, Speakers Bureau; Daiichi Sankyo: Research Funding; BiolineRx: Research Funding; Janssen-Cilag GmbH: Speakers Bureau. Platzbecker:Novartis: Consultancy, Honoraria, Research Funding; Amgen: Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Geron: Consultancy, Honoraria. Thiede:AgenDix GmbH: Other: Co-owner and CEO. OffLabel Disclosure: Off-label: treatment with azacitidine to prevent or substantially delay an overt relapse in MRD-positive patients with MDS or AML