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Internal tandem duplications (ITD) in the receptor tyrosine kinase FLT3 occur in 25 % of acute myeloid leukemia (AML) patients, drive leukemia progression and confer a poor prognosis. Primary resistance to FLT3 kinase inhibitors (FLT3i) quizartinib, crenolanib and gilteritinib is a frequent clinical challenge and occurs in the absence of identifiable genetic causes. This suggests that adaptive cellular mechanisms mediate primary resistance to on-target FLT3i therapy. Here, we systematically investigated acute cellular responses to on-target therapy with multiple FLT3i in FLT3-ITD + AML using recently developed functional translatome proteomics (measuring changes in the nascent proteome) with phosphoproteomics. This pinpointed AKT-mTORC1-ULK1-dependent autophagy as a dominant resistance mechanism to on-target FLT3i therapy. FLT3i induced autophagy in a concentration- and time-dependent manner specifically in FLT3-ITD + cells in vitro and in primary human AML cells ex vivo. Pharmacological or genetic inhibition of autophagy increased the sensitivity to FLT3-targeted therapy in cell lines, patient-derived xenografts and primary AML cells ex vivo. In mice xenografted with FLT3-ITD + AML cells, co-treatment with oral FLT3 and autophagy inhibitors synergistically impaired leukemia progression and extended overall survival. Our findings identify a molecular mechanism responsible for primary FLT3i treatment resistance and demonstrate the pre-clinical efficacy of a rational combination treatment strategy targeting both FLT3 and autophagy induction.

Little is known about the cellular immune response to SARS-CoV-2 vaccination in patients after HSCT and B-NHL with iatrogenic B-cell aplasia. In nonseroconverted HSCT patients, induction of specific T-cell responses was assessed. The majority of allogeneic HSCT patients not showing humoral responses to vaccination also fail to mount antigen-specific T-cell responses.

Burkitt lymphoma (BL) is an aggressive lymphoma type that is currently treated by intensive chemoimmunotherapy. Despite the favorable clinical outcome for most patients with BL, chemotherapy-related toxicity and disease relapse remain major clinical challenges, emphasizing the need for innovative therapies. Using genome-scale CRISPR-Cas9 screens, we identified B-cell receptor (BCR) signaling, specific transcriptional regulators, and one-carbon metabolism as vulnerabilities in BL. We focused on serine hydroxymethyltransferase 2 (SHMT2), a key enzyme in one-carbon metabolism. Inhibition of SHMT2 by either knockdown or pharmacological compounds induced anti-BL effects in vitro and in vivo. Mechanistically, SHMT2 inhibition led to a significant reduction of intracellular glycine and formate levels, which inhibited the mTOR pathway and thereby triggered autophagic degradation of the oncogenic transcription factor TCF3. Consequently, this led to a collapse of tonic BCR signaling, which is controlled by TCF3 and is essential for BL cell survival. In terms of clinical translation, we also identified drugs such as methotrexate that synergized with SHMT inhibitors. Overall, our study has uncovered the dependency landscape in BL, identified and validated SHMT2 as a drug target, and revealed a mechanistic link between SHMT2 and the transcriptional master regulator TCF3, opening up new perspectives for innovative therapies.

Biallelic mutations of the CEBPA gene (CEBPAbi) define a distinct entity associated with favorable prognosis; however, the role of monoallelic mutations (CEBPAsm) is poorly understood. We retrospectively analyzed 4708 adults with acute myeloid leukemia (AML) who had been recruited into the Study Alliance Leukemia trials, to investigate the prognostic impact of CEBPAsm. CEBPA mutations were identified in 240 patients (5.1%): 131 CEBPAbi and 109 CEBPAsm (60 affecting the N-terminal transactivation domains [CEBPAsmTAD] and 49 the C-terminal DNA-binding or basic leucine zipper region [CEBPAsmbZIP]). Interestingly, patients carrying CEBPAbi or CEBPAsmbZIP shared several clinical factors: they were significantly younger (median, 46 and 50 years, respectively) and had higher white blood cell (WBC) counts at diagnosis (median, 23.7 × 109/L and 35.7 × 109/L) than patients with CEBPAsmTAD (median age, 63 years, median WBC 13.1 × 109/L; P < .001). Co-mutations were similar in both groups: GATA2 mutations (35.1% CEBPAbi; 36.7% CEBPAsmbZIP vs 6.7% CEBPAsmTAD; P < .001) or NPM1 mutations (3.1% CEBPAbi; 8.2% CEBPAsmbZIP vs 38.3% CEBPAsmTAD; P < .001). CEBPAbi and CEBPAsmbZIP, but not CEBPAsmTAD were associated with significantly improved overall (OS; median 103 and 63 vs 13 months) and event-free survival (EFS; median, 20.7 and 17.1 months vs 5.7 months), in univariate and multivariable analyses. Additional analyses revealed that the clinical and molecular features as well as the favorable survival were confined to patients with in-frame mutations in bZIP (CEBPAbZIP-inf). When patients were classified according to CEBPAbZIP-inf and CEBPAother (including CEBPAsmTAD and non-CEBPAbZIP-inf), only patients bearing CEBPAbZIP-inf showed superior complete remission rates and the longest median OS and EFS, arguing for a previously undefined prognostic role of this type of mutation.

Three reports address the protection of the vulnerable population of patients with hematologic malignancies in the face of the ongoing COVID pandemic. The reports suggest that some patients who fail to mount a B-cell response to vaccine may nevertheless have protective T cell responses. As a group, these reports suggest that patients should continue to be immunized with additional doses to attempt to improve immune response but that they need to maintain the precautions recommended for the unvaccinated.

To design a simple and reproducible classifier predicting the overall survival (OS) of patients with acute myeloid leukemia (AML) ≥60 years of age treated with 7 + 3, we sequenced 37 genes in 471 patients from the ALFA1200 (Acute Leukemia French Association) study (median age, 68 years). Mutation patterns and OS differed between the 84 patients with poor-risk cytogenetics and the 387 patients with good (n = 13), intermediate (n = 339), or unmeasured (n = 35) cytogenetic risk. TP53 (hazards ratio [HR], 2.49; P = .0003) and KRAS (HR, 3.60; P = .001) mutations independently worsened the OS of patients with poor-risk cytogenetics. In those without poor-risk cytogenetics, NPM1 (HR, 0.57; P = .0004), FLT3 internal tandem duplications with low (HR, 1.85; P = .0005) or high (HR, 3.51; P < 10−4) allelic ratio, DNMT3A (HR, 1.86; P < 10−4), NRAS (HR, 1.54; P = .019), and ASXL1 (HR, 1.89; P = .0003) mutations independently predicted OS. Combining cytogenetic risk and mutations in these 7 genes, 39.1% of patients could be assigned to a “go-go” tier with a 2-year OS of 66.1%, 7.6% to the “no-go” group (2-year OS 2.8%), and 3.3% of to the “slow-go” group (2-year OS of 39.1%; P < 10−5). Across 3 independent validation cohorts, 31.2% to 37.7% and 11.2% to 13.5% of patients were assigned to the go-go and the no-go tiers, respectively, with significant differences in OS between tiers in all 3 trial cohorts (HDF [Hauts-de-France], n = 141, P = .003; and SAL [Study Alliance Leukemia], n = 46; AMLSG [AML Study Group], n = 223, both P < 10−5). The ALFA decision tool is a simple, robust, and discriminant prognostic model for AML patients ≥60 years of age treated with intensive chemotherapy. This model can instruct the design of trials comparing the 7 + 3 standard of care with less intensive regimens.

Background: Trisomy 4 is a recurrent but rare cytogenetic abnormality reported in patients with acute myeloid leukemia (AML). The prognostic significance of this abnormality in AML patients is not clear. Prognosis of AML patients with trisomy 4 seems to be poor as compared to that of patients with intermediate-risk cytogenetics. Allogeneic hematopoietic stem cell transplantation (allo-HCT) may improve survival if applied early in first complete remission (CR). However, neither prospective clinical nor larger retrospective cohort studies are available to support these results from small series. Aims: To characterize AML patients with trisomy 4 and compare outcomes according to different treatment strategies. Methods: We retrospectively studied 123 AML patients with trisomy 4 (median age at diagnosis, 58 years; range, 16-76 years) treated between 2000 and 2019 within 2 large study groups. Standard statistical methods were applied. Results: Median white blood cell count at diagnosis was 4.8/nl (range, 0.4-255/nl) and platelets 46/nl (range, 2-330/nl). Type of AML was de novo in 97 (79%), secondary after myelodysplastic syndrome/myeloproliferative neoplasm in 18 (15%), and therapy-related in 8 (6%) patients. Sixty-two (50%) patients were female. Cytogenetic analysis revealed trisomy 4 as the sole abnormality in 28 (23%), additional abnormalities in 95 (77%) patients, most frequently ≥3 (n=66) abnormalities, trisomy 8 (n=41), karyotypes characterized by trisomies only (n=21) and t(8;21) or inv(16) (CBF; n=10). A total of 98 patients (80%) had NPM1 and FLT3-ITD mutation testing. Of those, 21 (21%) and 15 (15%) harbored NPM1 and FLT3-ITD mutations. Only 2 (3%) of 72 patients were CEBPA double mutated. Data on response to intensive anthracycline-based induction therapy were available in 117 patients. Early death rate was 5% (n=6). CR was achieved in 68% (n=79) with 22 (19%) requiring an intensive salvage treatment cycle. Notably, patients with trisomy 4 as sole abnormality had a CR rate of 89% (n=25/28). There was no difference in the CR rate in FLT3-ITD positive (n=10/15) as compared to FLT3 wild type (n=56/83) patients (67% each, P=0.99). Univariable analysis revealed trisomy 4 as sole abnormality (OR, 5.76; P=0.007) and NPM1 (OR, 12.08; P=0.02) as favorable factors. An allo-HCT was performed in 40 (34%) patients, of whom 19 patients were transplanted in first CR after induction therapy. Nine patients achieved CR after salvage chemotherapy and went on to allo-HCT; another 12 patients received allo-HCT with active disease. Type of donor was matched-related in 8, matched-unrelated in 30, and unknown in 2 of the 40 patients, respectively. Median follow-up of the intensively treated cohort was 73 months (95%-CI, 36-91 months). Five-year overall survival (OS) and relapse-free survival (RFS) were 31% (95%-CI, 23-42%) and 27% (95%-CI, 18-42%). OS rates were significantly higher in patients with CBF leukemia or patients with trisomy 4 as compared to all other abnormalities (Figure 1; P Conclusions: Clinically, patients with trisomy 4 are very heterogeneous in particular with respect to cytogenetic and molecular abnormalities. In our cohort, patients with trisomy 4 as a sole abnormality had a high CR rate and favorable clinical outcome. In the total cohort, allo-HCT did not improve RFS. Figure 1 Figure 1. Disclosures Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: Takeda: Consultancy, Honoraria; Bayer Vital: Honoraria; Jazz: Consultancy, Honoraria; GSK: Consultancy; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Crysandt: Incyte: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees. Fransecky: Medac: Honoraria; Amgen: Honoraria; Abbvie: Honoraria, Research Funding; Novartis: Honoraria; Takeda: Honoraria. Martinez-Lopez: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Platzbecker: AbbVie: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Geron: Honoraria; Takeda: Honoraria. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Levis: Astellas and FujiFilm: Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Honoraria; Amgen, Astellas Pharma, Daiichi-Sankyo, FujiFilm, and Menarini: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria; Takeda: Honoraria. Montesinos: Stemline/Menarini: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Glycomimetics: Consultancy; Tolero Pharmaceutical: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau. Röllig: Roche: Honoraria, Research Funding; Bristol-Meyer-Squibb: Honoraria, Research Funding; Janssen: Honoraria; Jazz: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Honoraria; AbbVie: Honoraria, Research Funding. Schlenk: Novartis: Honoraria; Pfizer: Honoraria, Research Funding, Speakers Bureau; Hexal: Honoraria; Neovio Biotech: Honoraria; Daiichi Sankyo: Honoraria, Research Funding; Celgene: Honoraria; Astellas: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria; Agios: Honoraria; Roche: Honoraria, Research Funding; AstraZeneca: Research Funding; Boehringer Ingelheim: Research Funding.

Abstract Multiple myeloma patients are often treated with immunomodulatory drugs, proteasome inhibitors, or monoclonal antibodies until disease progression. Continuous therapy in combination with the underlying disease frequently results in severe humoral and cellular immunodeficiency, which often manifests in recurrent infections. Here, we report on the clinical management and immunological data of three multiple-myeloma patients diagnosed with COVID-19. Despite severe hypogammaglobulinemia, deteriorated T cell counts, and neutropenia, the patients were able to combat COVID-19 by balanced response of innate immunity, strong CD8+ and CD4+ T cell activation and differentiation, development of specific T-cell memory subsets, and development of anti-SARS-CoV-2 type IgM and IgG antibodies with virus-neutralizing capacities. Even 12 months after re-introduction of lenalidomide maintenance therapy, antibody levels and virus-neutralizing antibody titers remained detectable, indicating persisting immunity against SARS-CoV-2. We conclude that in MM patients who tested positive for SARS-CoV-2 and were receiving active MM treatment, immune response assessment could be a useful tool to help guide decision-making regarding the continuation of anti-tumor therapy and supportive therapy. Key messages Immunosuppression due to multiple myeloma might not be the crucial factor that is affecting the course of COVID-19. In this case, despite pre-existing severe deficits in CD4+ T-cell counts and IgA und IgM deficiency, we noticed a robust humoral and cellular immune response against SARS-CoV-2. Evaluation of immune response and antibody titers in MM patients that were tested positive for SARS-CoV-2 and are on active MM treatment should be performed on a larger scale; the findings might affect further treatment recommendations for COVID-19, MM treatment re-introduction, and isolation measures.

NPM 1-mutated acute myeloid leukemia (AML) shows unique features. However, the characteristics of “therapy-related” NPM1-mutated AML (t-NPM1 AML) are poorly understood. We compared the genetics, transcriptional profile, and clinical outcomes of t-NPM1 AML, de novo NPM1-mutated AML (dn-NPM1 AML), and therapy-related AML (t-AML) with wild-type NPM1 (t-AML). Normal karyotype was more frequent in t-NPM1 AML (n = 78/96, 88%) and dn-NPM1 (n = 1986/2394, 88%) than in t-AML (n = 103/390, 28%; P < .001). DNMT3A and TET2 were mutated in 43% and 40% of t-NPM1 AML (n = 107), similar to dn-NPM1 (n = 88, 48% and 30%; P > 0.1), but more frequently than t-AML (n = 162; 14% and 10%; P < 0.001). Often mutated in t-AML, TP53 and PPM1D were wild-type in 97% and 96% of t-NPM1 AML, respectively. t-NPM1 and dn-NPM1 AML were transcriptionally similar, (including HOX genes upregulation). At 62 months of median follow-up, the 3-year overall survival (OS) for t-NPM1 AML (n = 96), dn-NPM1 AML (n = 2394), and t-AML (n = 390) were 54%, 60%, and 31%, respectively. In multivariable analysis, OS was similar for the NPM1-mutated groups (hazard ratio [HR] 0.9; 95% confidence interval [CI], 0.65-1.25; P = .45), but better in t-NPM1 AML than in t-AML (HR, 1.86; 95% CI, 1.30-2.68; P < .001). Relapse-free survival was similar between t-NPM1 and dn-NPM1 AML (HR, 1.02; 95% CI, 0.72-1.467; P = .90), but significantly higher in t-NPM1 AML versus t-AML (HR, 1.77; 95% CI, 1.19-2.64; P = .0045). t-NPM1 and dn-NPM1 AML have overlapping features, suggesting that they should be classified as a single disease entity.

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 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.

Background Venetoclax (VEN)-based combination therapy with hypomethylating agents (HMA) has been approved for first-line treatment in patients ineligible for intensive treatment based on two randomized trials. There is some evidence for efficacy also in the in relapsed/ refractory setting (R/R), but comparative controlled data is lacking. Here, we report our experience of VEN-Azacitidine (AZA) in R/R AML salvage treatment and bridge to allogeneic cell transplantation (allo-HCT) in fit patients compared to historical data from the Study Alliance Leukemia (SAL) registry (ClinicalTrials.gov Identifier: NCT03188874). Design/Methods We analyzed all patients with R/R AML after initial intensive therapy, who started VEN-AZA salvage treatment at the University Hospital Heidelberg, between October 2018 and October 2020. Patients, who were bridged to allo-HCT were compared in a multivariable analysis to data of R/R AML patients from the SAL registry receiving an allo-HCT. Results: A total of 26 patients (median age 60 years, range 23 to 79) were included. All patients initially received intensive therapy, 16 patients (62%) had been refractory to intensive induction therapy with DA (daunorubicin, cytarabine) (11 patients)/ CPX-351 (2 patients) or to an intensive salvage therapy regime with HAM (2 patients)/ Cytarabin-Bortezomib (1 patient). Ten patients (38%) had morphologic (7 patients) or molecular relapse (3 patients) after intensive first line therapy. The distribution of AML according to WHO-2016 classification was n=10 recurrent genetic abnormalities (n= 7, mutated NPM1; n=1, biallelic CEBPA mutations; n=1, mutated RUNX1; n=1, CBFB-MYH11), n=10 AML with MRC, n=6 AML NOS. According to the 2017 ELN classification, 9 patients (34,5%) had low risk, 8 (31%) intermediate risk and 9 (34,5%) adverse risk disease. All patients received AZA 75mg/m² for 7 days combined with VEN 400mg/day after initial ramp up or a reduced dose of 100mg/day in case of co-medication with azoles in 28 days cycles. Best response was CR/CRi in 58% (n=15), PR in 23% (n=6) patients. Day 30-mortality was 0%, day 60-mortality was 4% (n=1). Allo-HCT was performed in 20 patients (77%). Pre-Allo-HCT remission status was CR/CRi in 11 (55%), PR in 4 (20%) patients and MLFS in 1 patient and 4 patients had active disease (n=3, relapse after achieving CR/CRi on VEN-AZA, n=1 refractory to VEN-AZA.). At the time of analysis 15 (75%) of the 20 bridged patients were alive and 11 (55%) are still in CR resulting in a median relapse-free survival in bridged patients of 406 days, whereas all patients not proceeding to allo-HCT died after a median of 139 days. In total, 63 patients with R/R AML were identified in the SAL-registry proceeding to allo-HCT with non VEN-based salvage attempt. Pre-Allo-HCT remission status was CR/CRi in 18 (28%), PR in 15 (24%), unknown in 13 patients (21%) and 17 (27%) patients had active disease (n=9 relapsed, n=8 refractory). Patients of the SAL registry were younger (median, 55 years; range, 22-75 years) and more patients were ELN-int (low risk, 32%, n=20; int, 52%, n=33, adv, 16%, n=10). Median follow-up in the VEN-AZA and the SAL cohorts were 1.4 years and 4.6 years, respectively. Cox-regression modeling of survival measured from the date of being refractory/relapsed revealed a non-significant effect of the cohorts favoring the VEN-AZA salvage therapy (HR, 0.87, p=0.73). However, stratified univariable survival analysis revealed in trend better survival (p=0.10) in the VEN-AZA compared to the SAL cohort with 77% (95%-CI, 62-95%) and 74% (95%-CI, 57-97%) as well as 84% (95%-CI, 76-94%) and 52% (95-CI, 41-68%) 1- and 2-years survival, respectively. Conclusion: Our data confirms the efficacy of VEN-AZA in patients with R/R AML and underlines its potential as an effective strategy for bridging to successful allo-HCT. Disclosures Unglaub: JazzPharma: Consultancy, Other: travel costs/ conference fee; Novartis: Consultancy, Other: travel costs/ conference fee. Schlenk: Boehringer Ingelheim: Research Funding; AstraZeneca: Research Funding; Roche: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria; Neovio Biotech: Honoraria; Hexal: Honoraria; Daiichi Sankyo: Honoraria, Research Funding; Celgene: Honoraria; Astellas: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria; Agios: Honoraria. Middeke: Janssen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Gilead: Consultancy; Abbvie: Consultancy, Honoraria; Jazz: Consultancy; Pfizer: Consultancy, Honoraria; Sanofi: Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Novartis: Consultancy; Glycostem: Consultancy; UCB: Honoraria. Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: GSK: Consultancy; Jazz: Consultancy, Honoraria; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Crysandt: Pfizer: Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria. Fransecky: Medac: Honoraria; Abbvie: Honoraria, Research Funding; Amgen: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Seggewiss-Bernhardt: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; ipsen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; EusaPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees. Platzbecker: AbbVie: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Geron: Honoraria; Takeda: Honoraria. Baldus: Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria; Novartis: Honoraria. Dreger: Bluebird Bio: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; BMS: Consultancy; AbbVie: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Speakers Bureau. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Sauer: Takeda: Consultancy, Other: DSMB/SAB Member; Matterhorn Biosciences AG: Consultancy, Other: DSMB/SAB Member; Abbvie: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau. OffLabel Disclosure: off-label use of Venetoclax-based combination therapy in relapsed or refractory AML

Allogeneic hematopoietic cell transplantation (HCT) offers the highest chance for cure in patients with adverse-risk acute myeloid leukemia (AML) when performed in first remission (CR1). In contrast, patients in CR1 with favorable risk do not seem to benefit from allogeneic HCT due to the inherent risk of transplant-related mortality. Donor vs. no donor comparisons as well as prospective matched-pair analyses have suggested that allogeneic HCT performed in intermediate-risk AML may provide a higher probability of overall survival or relapse-free survival in patients ≤ 60 years of age with an acceptable risk for transplant-related mortality. On the other hand, many intermediate-risk patients relapsing after conventional chemotherapy may be successfully salvaged by allogeneic HCT. The role of allogeneic HCT in cytogenetically defined intermediate-risk AML patients in CR1 was addressed by a prospective randomized trial performed in 16 centers in Germany. Key inclusion criteria were: AML with intermediate-risk cytogenetics, first CR or CRi after conventional induction therapy, age of 18-60 years, and availability of an HLA-matched sibling or unrelated donor. For unrelated donors, a 9 out of 10 HLA allelic match was acceptable except for patients with an NPM1 mutation, for whom full 10/10 allele matching was required. Randomization was stratified according to age (< 40 vs. 40-60), NPM1/FLT3, and CEBP-alpha mutational status and unrelated vs. related donor availability. Endpoints included overall-survival as primary outcome and relapse-free survival (RFS), cumulative incidence of relapse, treatment-related mortality, and quality of life measured according to the short form (36) health status. From 2010 - 2018, 143 patients in CR1 were randomized into Arm A (n=76, allogeneic HCT) and Arm B (n=67, conventional consolidation and allo-HCT only in case of relapse). In July 2018, the trial was stopped prematurely due to slow accrual (143 out of 356 pts. randomized). Median age of the trial cohort was 51 years (range, 19-60), with 42% exhibiting an NPM1 and 25% a FLT3 mutation. A normal karyotype was reported in 84% of the included patients. All mentioned characteristics did not differ between both treatment arms. Sibling donors were available for 44 (31% of patients), matched unrelated donors for 99 (69%) patients. According to the intent-to-treat analysis, the probability of survival at 2 years was 71% (95% CI 60-81%) and 84% (95% CI 73-92%) in Arm A (Transplant) and Arm B (conventional consolidation), respectively (p=0.120, Figure 1A). RFS after allogeneic HCT was 69% (95% CI 57-80%) compared to 41% (95% CI 29-54%) after conventional consolidation (p=0.001, Figure 1B). Primary allogeneic HCT reduced the cumulative incidence of relapse at 2 years from 57% [95%-CI 46-71%] after conventional consolidation to 20% [95%-CI 13-31%] after HCT (p SF (36) scoring suggested a trend towards a lower physical functioning throughout the first 3 months after randomization in the primary HCT arm. No significant differences in vitality, mental health, social and emotional functioning could be documented between both treatment arms. In summary, the results of this first prospective randomized trial did not show that allogeneic HCT performed immediately after achievement of CR1 in patients with cytogenetically defined intermediate-risk AML ≤ 60 years of age conveys an overall survival advantage. However, allogeneic HCT in CR1 significantly reduced the relapse risk and was not associated with relevant impairments in quality of life. Although the limited statistical power of the trial does not allow definitive conclusions, delayed allogeneic transplantation seems to be a potential treatment algorithm in CR1 intermediate-risk AML with an available donor. Figure 1 Figure 1. Disclosures Schliemann: Jazz Pharmaceuticals: Consultancy, Research Funding; Roche: Consultancy; Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; Novartis: Consultancy; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; BMS: Consultancy, Other: travel grants. Schetelig: Roche: Honoraria, Other: lecture fees; Novartis: Honoraria, Other: lecture fees; BMS: Honoraria, Other: lecture fees; Abbvie: Honoraria, Other: lecture fees; AstraZeneca: Honoraria, Other: lecture fees; Gilead: Honoraria, Other: lecture fees; Janssen: Honoraria, Other: lecture fees . Glass: Riemser: Research Funding; Roche: Consultancy, Research Funding, Speakers Bureau; Kite: Consultancy; BMS: Consultancy; Novartis: Consultancy; Helios Klinik Berlin-Buch: Current Employment. Platzbecker: Janssen: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Geron: Honoraria; AbbVie: Honoraria. Burchert: Novartis: Honoraria, Research Funding; AOP Orphan: Honoraria, Research Funding; Pfizer: Honoraria; Incyte: Honoraria; Gilead: Honoraria; BMS: Honoraria. Haenel: Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Mueller: Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; CTI: Membership on an entity's Board of Directors or advisory committees; Gentium: Other: Travel Support; Gilead: Other: Travel Support; Janssen: Other: Travel Support; Novartis: Other: Travel Support; Pfizer: Other: Travel Support; Sanofi: Other: Travel Support. Berdel: Philogen S.p.A.: Consultancy, Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees. Stelljes: Novartis: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Medac: Speakers Bureau; Amgen: Consultancy, Speakers Bureau.

Background Recurrent somatic mutations in blood stem cells cause the emergence of mutated blood cell clones, known as clonal hematopoiesis (CH). Mutations in the most prevalent driver genes DNMT3A and TET2 with a variant allele frequency (VAF)≥2% have been associated with atherosclerosis and chronic heart failure (CHF). However, the effects of mutations in other driver genes for CH with low VAF ( Purpose To assess the potential prognostic significance of mutations in distinct genes other than DNMT3A and TET2 causing CH at low VAF in patients with CHF due to post-ischemic origin. Methods We analyzed mononuclear bone marrow and peripheral blood cells from 400 CHF patients by deep error-corrected targeted amplicon sequencing allowing for the detection of very low VAF of ≥0.5% in 56 CH driver genes and associated such with the long-term mortality in these patients. Results Median age of the patients was 63 and median follow-up time was 4.8 years. We detected 1116 mutations with a VAF≥0.5% in 348 of 400 patients (87%). 21% of the patients carried 1 mutation, whereas 66% showed 2 and more mutations. Only 52 (13%) patients had no detectable mutation at all. Despite a high prevalence of mutations in the most frequently mutated driver genes DNMT3A (165 patients) and TET2 (107 pts), mutations in the genes CBL (8 pts), CEBPA (10 pts), PHF6 (22 pts), SMC1A (18 pts) and SRSF2 (14 pts) were associated with increased death compared to the average death rate of all patients (18.8%). To avoid confounding effects caused by the presence of DNMT3A and TET2 CHIP mutations, we excluded patients with DNMT3A-, TET2- and other CHIP-related mutations with a VAF≥2% for further analyses. Kaplan-Meier survival curve analyses revealed a significantly higher mortality in patients with mutations in either of the five genes, combined as the CH risk gene set for CHF (Fig. 1). Patients with mutations in the risk gene set (44 pts) did not differ from patients with mutations in other CH driver genes or without mutations with respect to age, cardiovascular risk factors, disease severity or CH clone size. By multivariate Cox proportional regression analysis, including the Seattle heart failure model (SHFM) score (as tertiles), death remained independently associated with the presence of mutations in the risk gene set (HR, 2.57; 95% CI, 1.30–5.10; p=0.007), in addition to SHFM score tertiles (tertile 2, HR, 2.36; 95% CI, 0.73–7.65 and tertile 3, HR, 7.96; 95% CI, 2.77–22.90). Conclusions Somatic mutations with low VAF in a distinct set of genes, namely in CBL, CEBPA, PHF6, SMC1A and SRSF2, are significantly associated with mortality in CHF, independently of the classical CHIP-driver mutations DNMT3A and TET2. Mutations in the CH risk gene set are prevalent in young CHF patients and comprise an independent risk factor for the outcome of CHF, potentially providing a novel tool for cardiovascular risk assessment and precision medicine in CHF. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (DFG)

Contains fulltext : 218279.pdf (Publisher’s version ) (Open Access) Patients with acute myeloid leukemia (AML) harboring FLT3 internal tandem duplications (ITDs) have poor outcomes, in particular AML with a high (>/=0.5) mutant/wild-type allelic ratio (AR). The 2017 European LeukemiaNet (ELN) recommendations defined 4 distinct FLT3-ITD genotypes based on the ITD AR and the NPM1 mutational status. In this retrospective exploratory study, we investigated the prognostic and predictive impact of the NPM1/FLT3-ITD genotypes categorized according to the 2017 ELN risk groups in patients randomized within the RATIFY trial, which evaluated the addition of midostaurin to standard chemotherapy. The 4 NPM1/FLT3-ITD genotypes differed significantly with regard to clinical and concurrent genetic features. Complete ELN risk categorization could be done in 318 of 549 trial patients with FLT3-ITD AML. Significant factors for response after 1 or 2 induction cycles were ELN risk group and white blood cell (WBC) counts; treatment with midostaurin had no influence. Overall survival (OS) differed significantly among ELN risk groups, with estimated 5-year OS probabilities of 0.63, 0.43, and 0.33 for favorable-, intermediate-, and adverse-risk groups, respectively (P < .001). A multivariate Cox model for OS using allogeneic hematopoietic cell transplantation (HCT) in first complete remission as a time-dependent variable revealed treatment with midostaurin, allogeneic HCT, ELN favorable-risk group, and lower WBC counts as significant favorable factors. In this model, there was a consistent beneficial effect of midostaurin across ELN risk groups.

In fit patients with newly diagnosed acute myeloid leukemia (AML), immediate treatment start is recommended due to the poor prognosis of untreated acute leukemia. We explored the relationship between time from diagnosis to treatment start (TDT) and prognosis in a large real-world data set from the German Study Alliance Leukemia–Acute Myeloid Leukemia (SAL-AML) registry. All registered non–acute promyelocytic leukemia patients with intensive induction treatment and a minimum 12 months of follow-up were selected (n = 2263). We analyzed influence of TDT on remission, early death, and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0 to 5, 6 to 10, 11 to 15, and >15 days of TDT, adjusted for influence of established prognostic variables on outcomes. Median TDT was 3 days (interquartile range, 2-7). Unadjusted 2-year OS rates, stratified by TDT of 0 to 5, 6 to 10, 11 to 15, and >15 days, were 51%, 48%, 44%, and 50% (P = .211). In multivariable Cox regression analysis accounting for established prognostic variables, the TDT hazard ratio as a continuous variable was 1.00 (P = .617). In OS analyses, separately stratified for age ≤60 and >60 years and for high vs lower initial white blood cell count, no significant differences between TDT groups were observed. Our study suggests that TDT is not related to survival. As stratification in intensive first-line AML treatment evolves, TDT data suggest that it may be a feasible approach to wait for genetic and other laboratory test results so that clinically stable patients are assigned the best available treatment option. This trial was registered at www.clinicaltrials.gov as #NCT03188874.

Background: Acute myeloid leukemia (AML) is characterized by a high relapse rate, indicating insufficient clearance of leukemia-initiating cells. Depending on genetic risk stratification, consolidating chemotherapy proves to significantly reduce the risk of relapse. In particular, in younger AML patients higher dosage of cytarabine appears to improve long-term outcome, while there is no apparent benefit of multiagent combination, compared to cytarabine monotherapy. However, to this end the optimal dosage of single agent cytarabine in consolidation therapy after 7+3 remission induction remains elusive. Methods: Here, we retrospectively assessed the impact of different dosages of cytarabine consolidation on outcome in a large real-world data set from the German Study Alliance Leukemia-Acute Myeloid Leukemia (SAL-AML) registry. Patients below 65 years of age, registered between April 2005 and September 2020 with non-acute promyelocytic leukemia, who attained complete remission after intensive induction and received at least one consolidation cycle with intermediate (IDAC) or high dose cytarabine (HiDAC) were selected. To account for differences in patient and disease characteristics between both groups, the average treatment effect was estimated by propensity score weighting. Results: 642 patients received HiDAC consolidation with a median dosage of 5794.88 (IQR, 4745.48-5971.56) mg/m 2/d with a median number of 3 cycles (IQR, 2-3), whereas 178 patients received IDAC consolidation with 1946.16 (IQR, 1869.51-2469.15) mg/m 2/d with a median of 2 cycles (IQR, 1-3). IDAC-treated patients showed in average a higher age (median (IQR) 58.5 (49-62) years vs. 50 (41-56) years) and more comorbidities with 43.8% having an HCT-CI score of 2-4, compared to 22.3% among HiDAC-treated patients. Alongside, significantly more secondary (5.1% vs. 3.1%) and therapy-related (12.4% vs. 4.1%) AML as well as more adverse (14.5% vs. 6.5%) and less favorable (40.6% vs. 56%) genetic risk features according to ELN 2017 risk classification were found among IDAC-treated patients. After propensity score weighting for differences in patient and disease characteristics, overall survival after 5 years was comparable between HiDAC-treated (71.1 %) and IDAC-treated (67.7%) patients. Moreover, no significant differences in relapse-free survival were observed after 5 years (47.4 vs. 45.2%). Notably, more patients treated with IDAC received allogeneic stem cell transplantation in first remission (37.6 vs. 19.8%) while significantly more HiDAC-treated patients underwent allogeneic stem cell transplantation in relapse (30.8 vs. 20.2%). Censoring for allogeneic stem cell transplantation in first remission revealed no significant survival difference with regard to cytarabine dosage. Considering only ELN favorable risk AML patients, there was no difference in 5-years overall (80.5% vs. 83.9%) nor relapse-free (57.7% vs. 56.8%) survival. Of note, significantly more patients treated with HiDAC suffered from ≥3 CTCAE infectious complications (56.7 vs. 44.1%), which was more striking in patients above 50 years of age. The rate of other ≥3 CTCAE non-hematological toxicities and secondary malignancies was comparable in both treatment groups. Conclusion: This retrospective analysis suggests no significant benefit of high dose cytarabine compared to intermediate dosages in consolidation for AML patients under 65 years of age, independent of ELN risk group. Disclosures Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Brummendorf: Takepart Media: Honoraria; Repeat Diagnostics: Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Patents & Royalties, Research Funding; Janssen: Honoraria; Bristol Myers: Research Funding. Fransecky: Abbvie: Honoraria, Research Funding; Medac: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Takeda: Honoraria. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Held: MSD: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Roche: Research Funding; Acortech Biopharma: Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Platzbecker: Janssen: Honoraria; Celgene/BMS: Honoraria; AbbVie: Honoraria; Geron: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Baldus: Amgen: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria; Jazz: Honoraria. Mueller-Tidow: Janssen Cilag: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Bioline: Consultancy, Research Funding.

Introduction Selinexor is an exportin-1 (XPO1) inhibitor which forces the nuclear retention and functional activation of tumor suppressor proteins, inducing apoptosis in cancer cells. Overexpression of XPO-1 is common in many tumors, including acute myeloid leukemia (AML). A phase II study, "SAIL", of selinexor with cytarabine and idarubicin in patients with relapsed/refractory AML was conducted by Fiedler et al. showing a high remission rate. To identify molecular predictors of response and survival we evaluated the molecular mutations and their course in selinexor treated patients. Methods All 42 patients treated in the SAIL trial were eligible to participate in this translational study. The main criterion for inclusion in the present study was availability of DNA from bone marrow or peripheral blood at 3 time points: initial AML diagnosis, screening for the SAIL trial and first response assessment on day 28 of cycle 1. A custom TruSight myeloid sequencing panel was used to identify molecular mutations at diagnosis. Molecular response was defined as variant-allele frequency (VAF) Results Eighteen patients were included for whom DNA was available for all three time points. The median age was 47.5 years (29-72), median prior therapies was 3 (1-9). 13 patients had de novo and 5 secondary/therapy-related AML. ELN risk at first diagnosis was favorable in eight, intermediate in five and adverse in three patients. Only one course of SAIL treatment was administered to all patients. 8 patients achieved morphologic complete remission (CR) or CR with incomplete hematologic recovery (CRi). 13 patients proceeded to allogeneic hematopoietic cell transplantation (alloHCT) or donor lymphocyte infusion. The median overall survival was 0.69 years. The molecular profile showed a predominance of secondary AML-type mutations. No clear pattern was found between mutation status and morphologic CR or CRi (Figure 1). Molecular response to the SAIL induction treatment was found in 6 of 14 patients who had a molecular marker. Mutations in FLT3 (FLT3-TKD=1, FLT3-ITD=2), SF3B1 and TP53 were associated with molecular response, whereas mutations in GATA2, CUX1, TET2, BCOR, DNMT3A, RAD21, ASXL1, SRSF2, and WT1 were associated with resistance. When comparing the molecular characteristics of patients achieving CR/CRi (n=8) and all other patients (n=10), a trend to achieve CR was observed among patients with NPM1 mutations (P=0.094), whereas mutations in ASXL1 (P=0.09) and SRSF2 (P=0.09) were associated with refractoriness. One of the responding patients received selinexor as maintenance therapy for four years. The patient was diagnosed with de novo AML with normal cytogenetics, with SF3B1 and SRSF2 mutations. The patient received an HLA-identical transplant after myeloablative conditioning, but relapsed 6 years after alloHCT. One cycle of selinexor/chemotherapy was administered and the patient achieved CR. The patient continued selinexor maintenance treatment with 60 mg selinexor twice a week. SF3B1 and SRSF2 mutations were still present at the time of relapse and declined under SAIL treatment (Figure 2). The patient received one course of DLI (1x10 7CD3 +), which was tolerated well without signs of GvHD. MRD remained detectable 17 days after DLI. At 30 days after DLI treatment both MRD markers were negative. Under continued selinexor maintenance treatment MRD remained negative until last follow-up at 4.9 years after SAIL treatment. The patient tolerated selinexor well with short-term nausea and dysgeusia after selinexor intake. Selinexor maintenance treatment was stopped 4 years after SAIL treatment and the patient remains in CR 14 months after the end of maintenance. Conclusion In this small series, we found a correlation between FLT3, TP53 and SF3B1 mutation status and molecular response to selinexor/chemotherapy (SAIL). NPM1 mutations were associated with morphologic response to SAIL by trend. Finally, selinexor maintenance may have contributed to long-term disease control in a patient with relapsed AML, and long term therapy with selinexor is feasible. Figure 1 Figure 1. Disclosures Fiedler: Servier: Consultancy, Other: Meeting attendance, Preparation of information material; Stemline: Consultancy; Daiichi Sanyko: Consultancy, Other: Meeting attendance, Preparation of information material; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; MorphoSys: Consultancy, Honoraria; Jazz: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material; Celgene: Consultancy, Honoraria; Ariad/Incyte: Honoraria; Amgen: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material, Patents & Royalties, Research Funding; Abbvie: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material. Modemann: Servier: Honoraria, Other: Travel accomodation; Incyte: Other: Travel accomodation; Gilead: Other: Travel accomodation; Jazz Pharmaceuticals: Other: Travel accomodation; Novartis: Other: Travel accomodation; Teva: Other: Travel accomodation; Pfizer: Other: Travel accomodation; Amgen: Other: Travel accomodation; Daiichi Sankyo: Research Funding; Abbvie: Honoraria, Other: Travel accomodation. Bokemeyer: Merck KGaA: Honoraria; Sanofi: Consultancy, Honoraria, Other: Travel accomodation; Roche: Honoraria, Research Funding; Bayer: Honoraria, Research Funding; BMS: Honoraria, Other: Travel accomodation, Research Funding; AstraZeneca: Honoraria, Research Funding; Merck Sharp Dohme: Consultancy, Honoraria; Lilly/ImClone: Consultancy; Merck Serono: Consultancy, Other: Travel accomodation ; Bayer Schering Pharma: Consultancy; GSO: Consultancy; AOK Health insurance: Consultancy; Abbvie: Research Funding; ADC Therapeutics: Research Funding; Agile Therapeutics: Research Funding; Alexion Pharmaceuticals: Research Funding; Amgen: Research Funding; Apellis Pharmaceuticals: Research Funding; Astellas: Research Funding; BerGenBio: Research Funding; Blueprint Medicine: Research Funding; Boehringer Ingelheim: Research Funding; Celgene: Research Funding; Daiichi Sankyo: Research Funding; Eisai: Research Funding; Gilead Sciences: Research Funding; Gylcotope GmbH: Research Funding; GlaxoSmithKline: Research Funding; Inside: Research Funding; IO Biotech: Research Funding; Isofol Medical: Research Funding; Janssen-Cilag: Research Funding; Karyopharm Therapeutics: Research Funding; Lilly: Research Funding; Millenium: Research Funding; MSD: Research Funding; Nektar: Research Funding; Rafael Pharmaceuticals: Research Funding; Springworks Therapeutics: Research Funding; Taiho Pharmaceutical: Research Funding; Pfizer: Other. Ganser: Celgene: Honoraria; Novartis: Honoraria; Jazz Pharmaceuticals: Honoraria. Thol: Astellas: Honoraria; Jazz: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; BMS/Celgene: Honoraria, Research Funding; Abbvie: Honoraria. Heuser: Karyopharm: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Research Funding; Roche: 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, Research Funding; Tolremo: Membership on an entity's Board of Directors or advisory committees; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer Pharma AG: Research Funding; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; BergenBio: Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Selinexor in patients with relapsed or refractory AML

Achievement of complete remission (CR) signifies a crucial milestone in the therapy of acute myeloid leukemia (AML) while refractory disease is associated with dismal outcomes. Hence, accurately identifying patients at risk is essential to tailor treatment concepts individually to disease biology. Machine Learning (ML) is a branch of computer science that can process large data sets for a plethora of purposes. The underlying mechanism does not necessarily begin with a manually drafted hypothesis model. Rather the ML algorithms can detect patterns in pre-processed data and derive abstract information. We used ML to predict CR and 2-year overall survival (OS) in a large multi-center cohort of 1383 AML patients who received intensive induction therapy using clinical, laboratory, cytogenetic and molecular genetic data. To enable a customizable and reusable technological approach and achieve optimal results, we designed a data-driven platform with an embedded, automated ML pipeline integrating state-of-the-art software technology for data management and ML models. The platform consists of five scalable modules for data import and modelling, data transformation, model refinement, machine learning algorithms, feature support and performance feedback that are executed in an iterative manner to approach step-wisely the optimal configuration. To reduce dimensionality and the the risk of overfitting, dynamic feature selection was used, i.e. features were selected according to their support by feature selection algorithms. To be included in an ML model, a feature had to pass a pre-determined threshold of overall predictive power determined by summing the normalized scores of the feature selection algorithms. Features below the threshold were automatically excluded from the ML models for the respective iteration. In that way, features of high redundancy or low entropy were automatically filtered out. Our classification algorithms were completely agnostic of pre-existing risk classifications and autonomously selected predictive features both including established markers of favorable or adverse risk as well as identifying markers of so-far controversial relevance. De novo AML, extramedullary AML, double-mutated (dm) CEBPA, mutations of CEBPA-bZIP, NPM1, FLT3-ITD, ASXL1, RUNX1, SF3B1, IKZF1, TP53, U2AF1, t(8;21), inv(16)/t(16;16), del5/del5q, del17, normal or complex karyotypes, age and hemoglobin at initial diagnosis were statistically significant markers predictive of CR while t(8;21), del5/del5q, inv(16)/t(16;16), del17, dm CEBPA, CEBPA-bZIP, NPM1, FLT3-ITD , DNMT3A, SF3B1, U2AF1, TP53, age, white blood cell count, peripheral blast count, serum LDH and Hb at initial diagnosis as well as extramedullary manifestations were predictive for 2-year OS. For prediction of CR and 2-year OS, AUROCs ranged between 0.77 - 0.86 and 0.63 - 0.74, respectively. We provide a method to automatically select predictive features from different data types, cope with gaps and redundancies, apply and optimize different ML models, and evaluate optimal configurations in a scalable and reusable ML platform. In a proof-of-concept manner, our algorithms utilize both established markers of favorable or adverse risk and also provide further evidence for the roles of U2AF1, IKZF1, SF3B1, DNMT3A and bZIP mutations of CEBPA in AML risk prediction. Our study serves as a fundament for prospective validation and data-driven ML-guided risk assessment in AML at initial diagnosis for the individual patient. Image caption: Patient features were automatically selected by machine learning to predict complete remission (CR) and 2-year overall survival (OS) after intensive induction therapy. Based on a continuous feature support metric with a predefined cut-off of 0.5 (determined by optimal classification performance), 27 and 25 features were automatically selected for prediction of CR (A) and 2-year OS (C), respectively. For each of these features predicted by machine learning, odds ratios and 95% confidence intervals (CI) were calculated for CR (B) and 2 year OS (D). BMB: bone marrow blast count; FLT3h/low: FLT3-ITD ratio, h=high>0.5; Hb: hemoglobin; karyotype, c: complex aberrant karyotype (≥ 3 aberrations); karyotype, n: normal karyotype (no aberrations); LDH: lactate dehydrogenase; PBB: peripheral blood blast count; PLT: platelet count; WBC: white blood cell count. Figure 1 Figure 1. Disclosures Schetelig: Roche: Honoraria, Other: lecture fees; Novartis: Honoraria, Other: lecture fees; BMS: Honoraria, Other: lecture fees; Abbvie: Honoraria, Other: lecture fees; AstraZeneca: Honoraria, Other: lecture fees; Gilead: Honoraria, Other: lecture fees; Janssen: Honoraria, Other: lecture fees . Platzbecker: Janssen: Honoraria; Celgene/BMS: Honoraria; AbbVie: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Geron: Honoraria. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Baldus: Celgene/BMS: Honoraria; Amgen: Honoraria; Novartis: Honoraria; Jazz: Honoraria. Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Haenel: Bayer Vital: Honoraria; Jazz: Consultancy, Honoraria; GSK: Consultancy; Takeda: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Middeke: Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Jazz: Consultancy; Astellas: Consultancy, Honoraria; Sanofi: Honoraria, Research Funding; Novartis: Consultancy; Gilead: Consultancy; Glycostem: Consultancy; UCB: Honoraria.

The outcome of AML patients (pts) ≥ 70 years is poor. Defining the best treatment option remains controversial especially when choosing between intensive chemotherapy (IC) and hypomethylating agents (HMAs). We set up a multicentric European database collecting data of AML pts ≥ 70 y. The primary objective was to compare overall survival in pts selected for IC or HMAs. Individual pt data were collected from 3 European AML registries (DATAML, SAL and PETHEMA). All pts ≥70 y newly diagnosed between 01/01/2007 and 06/30/2018 were included. Variables were age, sex, diagnosis date, AML status, WBC, BM blasts %, cytogenetic risk, NPM1, FLT3-ITD mutations, first-line therapy, response, allo-SCT in first complete remission (CR), date of relapse and/or death. First-line treatments included IC, a semi-intensive regimen (fludarabine, cytarabine, filgrastim), HMAs, low-dose cytarabine (LDAC) or supportive care (SC). 3 700 AML pts ≥ 70y were identified. Pts treated with semi-intensive chemotherapy (n=464), LDAC (n=127) or SC (n=837) were not included in this analysis. Thus, the study population included 1 199 IC pts and 1 073 HMA pts. The median follow-up was 49.5 months. In the HMA group, pts were older, had lower WBC count and BM blast %, and they more frequently had ECOG > 1, secondary AML (sAML) and adverse-risk cytogenetics (CG) compared to the IC group. NPM1 and FLT3-ITD mutations were more frequent in the IC group. IC regimens were daunorubicin-AraC (n=432, 36.0%), idarubicin-AraC (n=381, 31.8%) or ida-AraC-CCNU (n=214, 17.8%). AlloSCT was performed in 70 IC pts (5.8%) and only in 7 HMA pts (0.7%) (P CR/CRi was achieved in 673 (56.1%) and 211 (19.7%) pts in the IC and HMA groups (P 1, adverse-risk CG and WBC >30 giga/L were significantly associated with a lower response rate whereas NPM1 mutation was significantly associated with a higher response rate. HMA treatment was associated with a lower response rate than IC (OR, 0.25; 95%CI : 0.20-0.31 ; P Day-60 death occurred in 247 (20.6%) and 194 (18.1%) pts in the IC and HMA groups (P=0.129). MV analysis showed that age ≥ 75 years, ECOG > 1, adverse-risk CG and WBC > 30 giga/L were significantly associated with a higher d60 death rate. HMA treatment was associated with a lower d60 death rate than IC (OR, 0.69; 95%CI : 0.54-0.88 ; P=0.003). The median OS was 10.9 (95%CI: 9.7-11.6) and 9.2 months (95%CI: 8.3-10.2) in the IC and HMA groups. OS at 1, 3 and 5 y was 46.0 (95%CI: 43.0-48.9) vs. 40.6% (95%CI: 37.6-43.7), 20.8 (95%CI: 18.3-23.4) vs. 8.3% (95%CI: 6.5-10.4) and 12.4 (95%CI: 10.2-14.9) vs 2.8% (95%CI: 1.7-4.4) in the IC and HMA groups. In MV analysis, ECOG > 1, adverse-risk CG, WBC > 30 giga/liter and sAML were significantly associated with a poorer OS. The treatment effect on OS was time-dependent (Fig 1A). To account for the non-proportionality of risks, we used a Royston and Parmar model, which took into account the interactions between time and treatment effect and allowed graphical representation of the adjusted risk of death at all times during follow-up. This model showed that HMA pts had a significantly lower risk of death before 1.5 months of follow-up ; there was no significant difference between both groups between 1.5 and 4.0 months, and OS was significantly better with IC from 4.0 months of follow-up (Fig 1B). There was no significant interaction between treatment (HMAs vs. IC) and all confounding factors (in particular age, performance status or CG risk). We also used the propensity score method. A MV logistic regression model was generated to estimate for each pt a propensity score to receive HMAs or IC. The performance of the model was estimated with the c 2-Hosmer-Lemeshow statistic (P-value= 0.169) and the C-statistic (0.82, 95%CI: 0.81-0.84). The mean propensity score was 0.320 (±0.232) in IC (N=1199) and 0.642 (±0.234) in HMA (N=1073). Based on propensity score, 532 subjects with IC were matched with 532 subjects with HMAs. The mean propensity score was the same in IC and HMA (0.491 ± 0.219) in the matched sample. The results of HMAs vs. IC comparisons on response, early mortality and overall survival (Fig 1C-D) in this subgroup of propensity score-matched pts were similar to those of the MV analysis. With a fairly long median follow-up and a large number of pts, this study shows that IC remains the treatment strategy that offers better chances for prolonged survival compared with HMAs even in AML pts ≥ 70y. Figure 1 Figure 1. Disclosures Recher: Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MaatPharma: Research Funding. Bertoli: Astellas: Consultancy; BMS Celgene: Consultancy; AbbVie: Consultancy; Jazz Pharmaceuticals: Consultancy. Dumas: Daiichi-Sankyo: Consultancy; Astellas: Consultancy; BMS Celgene: Consultancy. Tavitian: Novartis: Consultancy. Platzbecker: AbbVie: Honoraria; Geron: Honoraria; Celgene/BMS: Honoraria; Takeda: Honoraria; Novartis: Honoraria; Janssen: Honoraria. Müller-Tidow: Janssen: Consultancy, Research Funding; Bioline: Research Funding; Pfizer: Research Funding. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. de la Fuente: Incyte: Consultancy, Speakers Bureau; Abbie: Consultancy, Speakers Bureau; Novartis: Research Funding; BMS: Consultancy, Speakers Bureau. Delabesse: Novartis: Consultancy; Astellas: Consultancy. Pigneux: Roche: Consultancy, Research Funding; BMS Celgene: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Amgen: Consultancy; Novartis: Consultancy, Research Funding. Montesinos: Stemline/Menarini: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Glycomimetics: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Tolero Pharmaceutical: Consultancy; Forma Therapeutics: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau.

Acute myeloid leukemia (AML) is a hematologic malignancy that is treated in medically fit patients with intensive induction chemotherapy (IT) and postremission therapy to achieve a complete and long-term remission. The incidence of obesity in the general population is steadily increasing and has been identified as a major risk factor for all-cause mortality. Despite previous studies assessing the role of obesity in AML patients undergoing IT, there is an ongoing debate on the impact of obesity on patient outcome as well as the optimal dosing strategy in obese AML patients. We conducted a retrospective registry study assessing 1677 AML patients who were treated with IT for newly diagnosed AML. The primary endpoint was overall survival (OS) while event-free survival (EFS), the rate of first complete remission (CR1), relapse/refractory disease and non-relapse/refractory-related mortality (NRRrM), treatment-related toxicities, patient comorbidities and chemotherapy dosing strategies were analyzed as secondary endpoints. Obese patients (body mass index, BMI ≥ 30) displayed a significant inferior median OS (29.44 vs. 47.94 months, p = 0.015) without a significant difference in median EFS (7.8 vs. 9.89 months, p = 0.3) compared to non-obese patients (BMI < 30). The cumulative incidence (CI) of NRRrM was significantly increased in obese patients compared to non-obese patients while no differences could be observed regarding the CI of relapsed or refractory disease. Obesity was identified as an independent risk factor for death (HR 1.27, [95% CI 1.07-1.51], p = 0.005) in a multivariable Cox regression analysis. When the cohort was stratified by age (≥/< 60 years), the difference in OS as well as the significantly increased CI of NRRrM was only observed in patients ≥ 60 years. Notably, obese patients demonstrated higher rates of cardiovascular and metabolic comorbidities regardless of their age. No disparities for OS, EFS, CR1 rate or treatment-related toxicities were observed when the entire study population was stratified for the used dosing strategy (dose calculation using total body weight, idealized body weight, adjusted idealized body weight or capped at body surface area of 2 m 2). In conclusion, the present study identifies obesity as a major independent risk factor for worse overall survival and increased CI of non-relapse/refractory-related mortality in older (≥60 years) AML patients undergoing curative IT. These findings may be most likely attributed to obesity related comorbidities and not to dose adaption of chemotherapy in obese AML patients. Disclosures Schliemann: Boehringer-Ingelheim: Research Funding; Abbvie: Consultancy, Other: travel grants; Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Astellas: Consultancy; AstraZeneca: Consultancy; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Haenel: Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Fransecky: Amgen: Honoraria; Abbvie: Honoraria, Research Funding; Novartis: Honoraria; Medac: Honoraria; Takeda: Honoraria. Burchert: Novartis: Honoraria, Research Funding; AOP Orphan: Honoraria, Research Funding; Pfizer: Honoraria; Incyte: Honoraria; Gilead: Honoraria; BMS: Honoraria. Crysandt: Incyte: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees. Müller-Tidow: Janssen: Consultancy, Research Funding; Bioline: Research Funding; Pfizer: Research Funding. Platzbecker: Celgene/BMS: Honoraria; AbbVie: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Geron: Honoraria. Baldus: Jazz: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria.

In the past decade outcome of adult ALL was improved significantly using pediatric-based chemotherapy in combination with risk-adapted stem cell transplantation (SCT) and targeted therapies. The GMALL Trial 08/2013 (NCT02881086) for patients (pts) aged 18-55 years (yrs) with newly diagnosed ALL/LBL has a BFM-based 2-phase induction, up to 8 cycles of PEG-asparaginase (ASP) with up to 7 cycles of HDMTX, HDAC, a reinduction phase and conventional maintenance up to 2.5 yrs. Two cycles Nelarabine are implemented for standard risk (SR) T-ALL. Pts with B-precursor-ALL (B-ALL) receive Rituximab independent of CD20 expression (Ph+ only if CD20+). Ph+ ALL pts receive Imatinib and a dose reduced induction (Vincristine, Dexamethasone, ASP). ASP is scheduled in induction 1 (IP1) (d 20) and 2 (d 34 for Ph+ and d 44 for Ph-) and dose is adapted to risk factors for hepatotoxicity. Pts with BMI>30 and/or liver steatosis receive 500 U/m 2, whereas 2000 U/m 2 is the standard dose. It is recommended to withhold the 2 nd dose of ASP in case of clinically relevant ASP-associated toxicities. Pts with high-risk (HR) features (WBC > 30,000/µl in B-ALL, pro B-ALL-, KMT2A rearrangement, early/mature T-ALL) or Ph+ ALL are considered for SCT in CR1 after 1 st consolidation (C1). Pts with MolFail (table 1) after C1 are candidates for targeted therapy (Blinatumomab, Nelarabin) followed by SCT. Randomization (R) I evaluates CNS irradiation versus i.th. prophylaxis in B- ALL/LBL. R II compares SCT versus SR therapy in HR pts with MolCR after induction. Both randomizations are blinded and not available for analysis. The trial is ongoing and scheduled to recruit 950 pts. Between 8/2017-4/2021 770 pts from 78 centers were included and 705 were evaluable. The median age was 35 (18-55) yrs, 638 had ALL (B,Ph-: 55%, Ph+: 20%, T: 25%,) and 67 pts LBL (B:12%; T:88%). For ALL the hematologic (Hem) CR rate after C1 was 93% and the MolCR Rate 61% (75% mol. response) (table 1). HemCR rate was 72% in LBL with 21% PR. PET CT was negative in half of the LBL PR cases. The lowest HemCR rate was observed in early T-ALL (83%) together with a MolCR rate of 45% (71% mol. response). In Ph- pts 2000 U/m 2 as first dose ASP was administered in 66%, 500 U/m 2 in 24%, no ASP in 1% and other doses in 9%. In pts with Ph+ ALL the respective numbers were 61%, 21%, 6% and 13%. For the 2nd dose the numbers were 43%, 21%,13% and 22% for Ph- and 41%, 24%, 13% and 22% for Ph+ pts. Bilirubine increases grade III/IV were observed in Ph- ALL in 18% of the cases treated with 500 U/m 2 vs 24% for 2000 U/m 2. In Ph+ ALL the respective numbers were 5% vs 3%. GOT/GPT grade III/IV increases were observed 29% of Ph- ALL pts treated with 500 U/m 2 vs 25% of those with 2000 U/m 2. The respective numbers for Ph+ ALL were 24% and 40%. At a median follow-up of 23 mo, the overall survival (OS) for all pts (N=705) was 88% and 76% at 1 and 3 yrs resp (subgroups see table 1). OS was correlated to age, 87%, 74%, 69% and 73% at 3 yrs for pts aged 18-25, 26-35, 36-45 and 46-55 yrs resp. SR T-ALL reached an OS of 86% at 3 yrs with a conventional and nelarabine based consolidation. 79% of pts with an indication for SCT were transplanted (64 sibling, 174 MUD). The OS of SCT pts after SCT was 75% at 3 yrs. 63 pts with MolFail became candidates for a targeted therapy, which was realized in 89% of the cases. The molecular response was evaluable in 51 pts and reached 55% (N=40) and 18% (N=11) after one cycle of Blinatumomab or Nelarabin resp. Pts with MolFail (N=63) achieved an OS of 84% at 1y and 72% at 3 years resp (71% for Ph- and 76% for Ph+). This large, ongoing prospective multicenter trial provides promising preliminary results. This applies also to those aged 45-55 yrs underlining that adult pts beyond the variable AYA definitions can benefit from pediatric-based therapy. Intensive and individualized ASP therapy was feasible. Whereas high HemCR rates were observed in nearly all subgroups, MolCR rates ranged from 41-74% and a relevant proportion remained MRD low positive underlining the need for detailed MRD classification. MRD-based targeted treatment was realized in a high proportion of pts. Responses to Blinatumomab in MolFail were lower compared to previous trials. Responses to Nelarabine in MolFail T-ALL pts were only 18%. OS of MolFail pts however was promising with the combination of targeted therapy and SCT. Thus, SCT is still a key component, contributing to improved outcomes although the overall proportion of SCT was lower than in previous GMALL trials. Funded by Deutsche Krebshilfe Figure 1 Figure 1. Disclosures Goekbuget: Servier: Consultancy, Other; Morphosys: Consultancy; Astra Zeneca: Other: Invited talk for company sponsored symposia (with honor); Amgen: Consultancy, Other: Invited talks for company sponsored symposia (with honoraria); Research funding for institution; Novartis: Consultancy, Other: Research funding for Institution; Pfizer: Consultancy, Other: Research funding for institution; Jazz Pharmaceuticals: Other: Research funding for institution; Incyte: Other: Research funding for Institution; Cellestia: Consultancy; Erytech: Consultancy; Abbvie: Other; Gilead/Kite: Consultancy. Stelljes: Pfizer: Consultancy, Research Funding, Speakers Bureau; Medac: Speakers Bureau; Amgen: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau. Viardot: Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; University Hospital of Ulm: Current Employment; F. Hoffmann-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Nachtkamp: Jazz: Honoraria; Bsh medical: Honoraria; Celgene: Other: Travel Support. Topp: Novartis: Consultancy; Roche: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy; Amgen: Consultancy, Research Funding; Macrogeniecs: Research Funding; Regeneron: Consultancy, Research Funding; Gilead: Research Funding; Universitatklinikum Wurzburg: Current Employment. Wäsch: Sanofi: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Pfizer: Consultancy; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Novartis: Consultancy; BMS/Celgene: Consultancy; Gilead: Consultancy. Vucinic: Abbvie: Honoraria, Other: Travel Sponsoring; MSD: Honoraria; Janssen: Honoraria, Other: Travel Sponsoring; Gilead: Honoraria, Other: Travel Sponsoring; Novartis: Honoraria. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. Brüggemann: Amgen: Other: Advisory Board, Travel support, Research Funding, Speakers Bureau; Incyte: Other: Advisory Board; Janssen: Speakers Bureau. Pfeifer: Incyte: Honoraria, Research Funding. Schwartz: Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants, Speakers Bureau; Novartis: Speakers Bureau; Jazz Pharmaceuticals: Other: Travel grants, Speakers Bureau; BTG International Inc: Membership on an entity's Board of Directors or advisory committees; MSD Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Basilea: Other: Travel grants; Gilead: Other: Travel grants, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Morphosys: Research Funding. Fiedler: Abbvie: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material; Amgen: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material, Patents & Royalties, Research Funding; Ariad/Incyte: Honoraria; Celgene: Consultancy, Honoraria; Jazz: Consultancy, Honoraria, Other: Meeting attendance, Preparation of information material; MorphoSys: Consultancy, Honoraria; Novartis: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Daiichi Sanyko: Consultancy, Other: Meeting attendance, Preparation of information material; Stemline: Consultancy; Servier: Consultancy, Other: Meeting attendance, Preparation of information material. OffLabel Disclosure: Nelarabine in newly diagnosed T-ALL

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 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

MRD in ALL is defined as the detection of leukemic cells in bone marrow below the microscopic threshold in complete remission (CR). Patients (pts) with molecular failure (MolFail) or molecular relapse (MolRel) after induction/consolidation therapy are at a high risk for hematologic relapse. Targeted therapies should prevent hematologic relapse, reduce MRD load and provide a bridging strategy to allogeneic stem cell transplantation (SCT) and thereby improve overall outcome of these pts. In pts without (wo) SCT option reduction of MRD load is an essential goal as well. Blinatumomab is an antibody construct that redirects CD3+ T cells to CD19+ target cells, resulting in a serial lysis of CD19+ B cells. In a study in pts with MRD ≥10-3, 78% achieved complete MRD response (Gökbuget N et al., Blood 2018). The MolAct1 trial was initiated by the GMALL study group to evaluate the efficacy and tolerability of Blinatumomab in MRD+ ALL including those with MRD below 10-3 and pts with MRD after SCT. Adults (≥18 yrs) with CD19+, Ph-negative BCP ALL in CR after ≥ 3 chemotherapies with MRD ≥10-4 were eligible (NCT03109093). Recruitment of pts with MRD ≥10-3 was stopped after marketing authorization for this entity. After an amendment, which became effective after 44 recruited pts, pts with MRD below 10-4 or non-quantifiable (nq) MRD were eligible. Blinatumomab 28 μg/day was given as 4-wk infusion, followed by a 2-wk break (1 cycle). Responders could receive up to 4 cycles or undergo HSCT after ≥ 1 cycle. MRD after 1 cycle was the primary endpoint. MRD was centrally assessed by allele-specific quantitative real-time PCR of clonal rearrangements of immunoglobulin or T-cell receptor genes. For definition of MRD at inclusion and at response assessment see table 1. 64 pts with a median age of 44 (18-83) yrs were included from 19 centers and 60 were evaluable. 63 pts were treated in first CR (5 after SCT). Overall, 67% achieved MolCR, 10% had MolFail, 23% MolNE. MolNE identifies an intermediate response with different options clarified table 1. 81% of the pts included with MRD ≥10-4 had a molecular response i.e. MolCR or MRD < 10-4. No significant differences in terms of MRD response were observed according to MRD level at inclusion or other patient characteristics (table 1). 60 pts have completed study treatment (40 HSCT, 8 relapses during treatment, 4 completed 4 cycles wo SCT, 2 stopped earlier due to toxicities - 1 with subsequent SCT, 1 due to GvHD, 1 due to physicians' decision and 4 pts returned to standard treatment after 2 cycles). SCT pts had a median age of 42 (18-66) yrs and follow-up is available in 37 / 41 pts (29 CCR, 3 relapse, 5 death in CR). 16 relapses occurred: 8 during treatment (1 after MolCR, 5 MolNE1-3 and 2 with MolFail resp); after SCT in 3/41 pts; 5/11 with CR at end of treatment wo subsequent SCT. The median observation time of surviving pts is 12 (1-38) mo and the median survival is not reached. At 2 yrs the survival probability (OS) was 64%. OS was 70%, 64% and 43% in pts with MRD between 10-4-10-3, 10-3-10-2 and >10-2 at inclusion, resp (p>.05; Fig.1). OS was 71% vs 54% in pts MolFail vs MolRel at inclusion (p>.05). OS was 72%, 40% and 56% in pts with MolCR, MolFail and MolNE after cycle 1 resp (P=0.02; Fig.2). Overall, the results from previous trials were confirmed. In addition, it was demonstrated that pts with MRD between 10-4 and 10-3 had a similar response and a trend towards better outcome compared to pts with higher MRD levels >10-2. So far only 7 pts with MRD below 10-4 were included; more data are needed to evaluate the impact of Blinatumomab in this population; GMALL does currently not recommend SCT for these pts unless there is an indication due to other risk factors. Interestingly, a significant proportion of pts (23%) had an incomplete MRD response and the outcome results indicate that these pts together with those with MolFail may have an inferior survival compared to those with MolCR. The results underline that the clear definition of MRD categories and consideration of level and sensitivity is essential for interpretation, which is possible due to well defined standards for the PCR method used here. 68% of the pts received SCT in CR after Blinatumomab with a so far limited mortality (13%). Further follow-up is certainly required. The GMALL will continue to recruit patients with MRD levels below 10-3 in order to improve their chances for long-term survival This study was supported by Amgen Inc. Disclosures Goekbuget: Servier: Consultancy, Research Funding; Jazz: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Erytech: Consultancy; Kite: Consultancy; Gilead: Consultancy. Schwartz:Pfizer: Other: personal fees ; AMGEN: Other: personal fees and non-financial support; BTG Intl Inc: Other: personal fees ; Gilead Sciences: Other: personal fees and non-financial support ; MSD Sharp & Dohme: Other: personal fees ; Basilea: Other: non-financial suppor; Novartis: Other: personal fees and non-financial support; Jazz Pharmaceuticals: Other: personal fees and non-financial support. Hüttmann:Lead Discovery Center GmbH: Consultancy; University Hospital Essen, University of Duisburg-Essen, Essen, Germany: Current Employment; Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Seattle Genetics: Research Funding; Roche: Other: Travel expenses; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Gilead: Honoraria. Viardot:Roche: Honoraria, Other: advisory board; Kite/Gilead: Honoraria, Other: advisory board; Novartis: Honoraria, Other: advisory board; Amgen: Honoraria, Other: advisory board. Fiedler:Daiichi Sankyo: Other: support for meeting attendance; Gilead: Other: support for meeting attendance; Jazz Pharmaceuticals: Honoraria, Other: support for meeting attendance; Abbvie: Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; ARIAD/Incyte: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Other: support for meeting attendance, Patents & Royalties, Research Funding. Alakel:Pfizer: Consultancy. Stelljes:Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Subklewe:Seattle Genetics: Research Funding; AMGEN: Consultancy, Honoraria, Research Funding; Morphosys: Research Funding; Gilead Sciences: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria; Janssen: Consultancy; Roche AG: Consultancy, Research Funding. Wäsch:Pfizer: Consultancy; Amgen: Consultancy; Janssen: Consultancy. Vucinic:Celgene: Honoraria. Fransecky:Amgen: Consultancy. Bargou:Amgen: Consultancy, Honoraria, Patents & Royalties; Gemoab: Consultancy, Honoraria; Cellex: Consultancy, Honoraria; Catalym: Consultancy, Honoraria. Topp:Amgen, Boehringer Ingelheim, KITE, Regeneron, Roche: Research Funding; Amgen, KITE, Novartis, Regeneron, Roche: Consultancy. Brüggemann:Regeneron: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy; Incyte: Consultancy; Roche: Consultancy; Affimed: Research Funding; Janssen: Consultancy, Honoraria. OffLabel Disclosure: Blinatumomab in MRD positive disease below 10-3

We studied acute myeloid leukemia (AML) patients with lympho-myeloid clonal hematopoiesis (LM-CH), defined by the presence of DNA methyltransferase 3A (DNMT3A) mutations in both the myeloid and lymphoid T-cell compartment. Diagnostic, complete remission (CR) and relapse samples were sequenced for 34 leukemia-related genes in 171 DNMT3A mutated adult AML patients. AML with LM-CH was found in 40 patients (23%) and was associated with clonal hematopoiesis of indeterminate potential years before AML, older age, secondary AML and more frequent MDS-type co-mutations (TET2, RUNX1 and EZH2). In 82% of AML patients with LM-CH, the preleukemic clone was refractory to chemotherapy and was the founding clone for relapse. Both LM-CH and non-LM-CH MRD-positive AML patients who achieved CR had a high risk of relapse after 10 years (75% and 75%, respectively) compared with patients without clonal hematopoiesis in CR with negative MRD (27% relapse rate). Long-term survival of patients with LM-CH was only seen after allogeneic hematopoietic stem cell transplantation (HSCT). We define AML patients with LM-CH as a distinct high-risk group of AML patients that can be identified at diagnosis through mutation analysis in T cells and should be considered for HSCT.

Background Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. Growing evidence indicates that tumor-initiating cells (TICs) are responsible for tumor growth and progression. Conventional chemotherapeutics do not sufficiently eliminate TICs, leading to tumor relapse. We aimed to gain insight into TIC biology by comparing the transcriptome of primary TIC cultures and their normal stem cell counterparts to uncover expression differences. Methods We established colonosphere cultures derived from the resection of paired specimens of primary tumor and normal mucosa in patients with CRC. These colonospheres, enriched for TICs, were used for differential transcriptome analyses to detect new targets for a TIC-directed therapy. Effects of target inhibition on CRC cells were studied in vitro and in vivo. Results Pathway analysis of the regulated genes showed enrichment of genes central to PI3K/AKT and Wnt-signaling. We identified CD133 as a marker for a more aggressive CRC subpopulation enriched with TICs in SW480 CRC cells in an in vivo cancer model. Treatment of CRC cells with the selective AKT inhibitor MK-2206 caused a decrease in cell proliferation, particularly in the TIC fraction, resulting in a significant reduction of the stemness capacity to form colonospheres in vitro and to initiate tumor formation in vivo. Consequently, MK-2206 treatment of mice with established xenograft tumors exhibited a significant deceleration of tumor progression. Primary patient-derived tumorsphere growth was significantly inhibited by MK-2206. Conclusion This study reveals that AKT signaling is critical for TIC proliferation and can be efficiently targeted by MK-2206 representing a preclinical therapeutic strategy to repress colorectal TICs. Electronic supplementary material The online version of this article (doi:10.1245/s10434-016-5218-z) contains supplementary material, which is available to authorized users.

We investigated the role of copy number alterations to refine risk stratification in adult Philadelphia chromosome positive (Ph)+ ALL treated with tyrosine kinase inhibitors (TKI) and allogeneic stem cell transplantation (aSCT). 97 Ph+ ALL patients (median age 41 years, range 18-64 years) within the prospective multicenter GMALL studies 06/99 (n=8) and 07/2003 (n=89) were analysed. All patients received TKI and aSCT in first complete remission (CR1). Copy number analysis was performed with SNP arrays and validated by multiplex ligation-dependent probe amplification (MLPA). The frequencies of recurrently deleted genes were: IKZF1, 76%, CDKN2A/2B, 45%, PAX5, 43%, BTG1, 18%, EBF1, 13%, ETV6, 5%, RB, 14%. In univariate analyses, the presence of CDKN2A/2B deletions had a negative impact on all endpoints: overall survival (p=0.023), disease free survival (p=0.012) and remission duration (p=0.036). The negative predictive value of CDKN2A/2B deletions was retained in multivariable analysis along with other factors such as timing of TKI therapy, intensity of conditioning, achieving remission after induction phase I and BTG1 deletions. We therefore conclude that acquired genomic CDKN2A/2B deletions identify a subgroup of Ph+ ALL patients, who have an inferior prognosis despite aSCT in CR1. Their poor outcome was attributable primarily to a high relapse rate after aSCT.

Introduction: Most patients with FLT3-ITD-positive AML, who relapse after allogenic stem cell transplantation (allo-SCT) die from their disease. Whether prophylactic FLT3-ITD inhibition with sorafenib can prevent AML relapse and improve outcome of patients in complete hematological remission (CHR) after allo-SCT is unknown and was tested in the SORMAIN trial. Methods: This randomized, double blind, placebo-controlled study was done at 14 centers in Germany and Austria. Patients with FLT3-ITD+ AML, aged 18 years or older, who had undergone allogenic stem cell transplantation from a HLA-matched sibling donor, 10/10 or 9/10 HLA-matched unrelated donor, and who were in confirmed CHR at the time of screening between day +30 and day +100 post allo-SCT, were included. Patients were randomly assigned (1:1) to receive either sorafenib (starting dose: 2 x 1 tbl. [2 x 200mg] qd, increasing every 14d to up to 2 x 2 tbl. [2 x 400mg] qd according to tolerability) or placebo (2 x 1 or 2 tbl. qd) for up to 24 months. Randomization was done centrally. In case of drug related adverse events, study medication could be interrupted, stepwise reduced to a minimum of 2 x 1 tbl. qd, temporarily withheld and recommenced at a lower dose level. FLT3-ITD diagnostics was done centrally at baseline and at time of relapse. In relapsing patients, off-label compassionate use of sorafenib was possible. The primary endpoint was relapse-free survival (RFS) as defined by either hematological relapse or death from any cause. The secondary endpoint was overall survival (OS). We here report the final RFS analysis. The OS results will be unblinded only prior to the ASH meeting and will be reported there. The SORMAIN study was terminated prior to full recruitment because of slow accrual. SORMAIN was registered with the European Clinical Trials Database (EudraCT 2010-018539-16) and the German Clinical Trials Register (DRKS00000591). Results: Between October 29, 2010, and May 17, 2016, 83 patients (41 males, 42 females) were randomized and included in the primary analysis (placebo, n=40; sorafenib, n=43). Median age was 54 years (IQR 47.75 - 61.33) for the entire study population and not significantly different between sorafenib and placebo groups. With a median follow up of 41.8 months after randomization (IQR 24.1 - 42.5), median RFS was 30.9 months (lower bound of 95% CI 5.2 months) in the placebo group versus not reached in the sorafenib group, corresponding to a 2-year RFS of 53,3 % (95% CI 36.5-67.5) in the placebo versus 85.0 % (69.5-93.0) in the sorafenib group (hazard ratio [HR] 0.39, 95% CI; 0.18 -0.85; P=0.0135) (Fig. 1). Overall, sorafenib was well tolerated. The most common grade 3-4 adverse event in both groups was acute GvHD (seven [ 17.5%] in the placebo group vs. nine [20.9%] in the sorafenib group. Conclusion: Sorafenib maintenance therapy after allo-SCT is feasible and significantly reduces the risk of relapse or death in patients with FLT3-ITD positive AML. OS results will be presented at the meeting. Figure 1. Figure 1. Disclosures Burchert: Bristol Myers Squibb: Honoraria, Research Funding; Bayer: Research Funding; Pfizer: Honoraria; AOP Orphan: Honoraria, Research Funding; Novartis: Research Funding. Bug:Amgen: Honoraria; Neovii: Other: Travel Grant; Novartis Pharma: Honoraria, Research Funding; Astellas Pharma: Other: Travel Grant; Jazz Pharmaceuticals: Other: Travel Grant; Celgene: Honoraria; Janssen: Other: Travel Grant. Finke:Riemser: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Other: travel grants, Research Funding; Neovii: Consultancy, Honoraria, Other: travel grants, Research Funding; Medac: Consultancy, Honoraria, Other: travel grants, Research Funding. Stelljes:Pfizer: Consultancy, Honoraria, Research Funding; MSD: Consultancy; JAZZ: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Rollig:Bayer: Research Funding; Janssen: Research Funding. Wäsch:Pfizer: Honoraria. Lang:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Research Funding. Ehninger:Cellex Gesellschaft fuer Zellgewinnung mbH: Employment, Equity Ownership; GEMoaB Monoclonals GmbH: Employment, Equity Ownership; Bayer: Research Funding. Serve:Bayer: Research Funding. Kroeger:Neovii: Honoraria, Research Funding; JAZZ: Honoraria; Sanofi: Honoraria; Celgene: Honoraria, Research Funding; Riemser: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Götze:JAZZ Pharmaceuticals: Honoraria; Novartis: Honoraria; Takeda: Honoraria, Other: Travel aid ASH 2017; Celgene: Honoraria, Research Funding. Schmid:Jazz Pharma: Honoraria, Other: Travel grant, Speakers Bureau. Wolf:BMS: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria, Research Funding; AOP Orphan: Honoraria, Research Funding. Thiede:AgenDix: Other: Ownership; Novartis: Honoraria, Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Bethge:Miltenyi Biotec GmbH: Consultancy, Honoraria, Research Funding; Neovii GmbH: Honoraria, Research Funding.

Acute myeloid leukemia (AML) is driven by niche-derived and cell-autonomous stimuli. Although many cell-autonomous disease drivers are known, niche-dependent signaling in the context of the genetic disease heterogeneity has been difficult to investigate. Here, we analyzed the role of Bruton tyrosine kinase (BTK) in AML. BTK was frequently expressed, and its inhibition strongly impaired the proliferation and survival of AML cells also in the presence of bone marrow stroma. By interactome analysis, (phospho)proteomics, and transcriptome sequencing, we characterized BTK signaling networks. We show that BTK-dependent signaling is highly context dependent. In Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD)–positive AML, BTK mediates FLT3-ITD–dependent Myc and STAT5 activation, and combined targeting of FLT3-ITD and BTK showed additive effects. In Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD)–negative AML, BTK couples Toll-like receptor 9 (TLR9) activation to nuclear factor κΒ and STAT5. Both BTK-dependent transcriptional programs were relevant for cell cycle progression and apoptosis regulation. Thus, we identify context-dependent oncogenic driver events that may guide subtype-specific treatment strategies and, for the first time, point to a role of TLR9 in AML. Clinical evaluation of BTK inhibitors in AML seems warranted.

Purpose The presence of a mutated nucleophosmin-1 gene (NPM1mut) in acute myeloid leukemia (AML) is associated with a favorable prognosis. To assess the predictive value with regard to allogeneic stem-cell transplantation (SCT), we compared the clinical course of patients with NPM1mut AML eligible for allogeneic SCT in a donor versus no-donor analysis. Patients and Methods Of 1,179 patients with AML (age 18 to 60 years) treated in the Study Alliance Leukemia AML 2003 trial, we identified all NPM1mut patients with an intermediate-risk karyotype. According to the trial protocol, patients were intended to receive an allogeneic SCT if an HLA-identical sibling donor was available. Patients with no available donor received consolidation or autologous SCT. We compared relapse-free survival (RFS) and overall survival (OS) depending on the availability of a suitable donor. Results Of 304 eligible patients, 77 patients had a sibling donor and 227 had no available matched family donor. The 3-year RFS rates in the donor and no-donor groups were 71% and 47%, respectively (P = .005); OS rates were 70% and 60%, respectively (P = .114). In patients with normal karyotype and no FLT3 internal tandem duplication (n = 148), the 3-year RFS rates in the donor and no-donor groups were 83% and 53%, respectively (P = .004); and the 3-year OS rates were 81% and 75%, respectively (P = .300). Conclusion Allogeneic SCT led to a significantly prolonged RFS in patients with NPM1mut AML. The absence of a statistically significant difference in OS is most likely a result of the fact that NPM1mut patients who experienced relapse responded well to salvage treatment. Allogeneic SCT in first remission has potent antileukemic efficacy and is a valuable treatment option in patients with NPM1mut AML with a sibling donor.

The optimal timing of allogeneic hematopoietic stem cell transplantation (HCT) in acute myeloid leukemia (AML) is controversial. We report on 1179 patients with a median age of 48 years who were randomized upfront. In the control arm, sibling HCT was scheduled in the first complete remission for intermediate-risk or high-risk AML and matched unrelated HCT in complex karyotype AML. In the experimental arm, matched unrelated HCT in first remission was offered also to patients with an FLT3-ITD (FMS-like tyrosine kinase 3-internal tandem duplication) allelic ratio >0.8, poor day +15 marrow blast clearance and adverse karyotypes. Further, allogeneic HCT was recommended in high-risk AML to be performed in aplasia after induction chemotherapy. In the intent-to-treat (ITT) analysis, superiority of the experimental transplant strategy could not be shown with respect to overall survival (OS) or event-free survival. As-treated analyses suggest a profound effect of allogeneic HCT on OS (HR 0.73; P=0.002) and event-free survival (HR 0.67; P

Maintenance therapy after allogeneic hematopoietic stem cell transplantation (HSCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) is conceptually attractive to prevent relapse, but has been hampered by the limited number of suitable anti-leukemic agents. The deacetylase inhibitor (DACi) panobinostat demonstrated moderate anti-leukemic activity in a small subset of patients with advanced AML and high-risk MDS in phase I/II trials.1, 2 It also displays immunomodulatory activity3 that may enhance leukemia-specific cytotoxicity4 and mitigate graft versus host disease (GvHD), but conversely could impair T- and NK cell function.5, 6 We conducted this open-label, multi-center phase I/II trial (NCT01451268) to assess the feasibility and preliminary efficacy of prolonged prophylactic administration of panobinostat after HSCT for AML or MDS. The study protocol was approved by an independent ethics committee and conducted in compliance with the Declaration of Helsinki. All patients provided written informed consent. ...

Acute myeloid leukemia in the elderly is characterized by a distinct genetic and epigenetic landscape

Leukemia, 31 (3), ISSN:1476-5551, ISSN:0887-6924

In acute myeloid leukemia (AML), therapy resistance frequently occurs, leading to high mortality among patients. However, the mechanisms that render leukemic cells drug resistant remain largely undefined. Here, we identified loss of the histone methyltransferase EZH2 and subsequent reduction of histone H3K27 trimethylation as a novel pathway of acquired resistance to tyrosine kinase inhibitors (TKIs) and cytotoxic drugs in AML. Low EZH2 protein levels correlated with poor prognosis in AML patients. Suppression of EZH2 protein expression induced chemoresistance of AML cell lines and primary cells in vitro and in vivo. Low EZH2 levels resulted in derepression of HOX genes, and knockdown of HOXB7 and HOXA9 in the resistant cells was sufficient to improve sensitivity to TKIs and cytotoxic drugs. The endogenous loss of EZH2 expression in resistant cells and primary blasts from a subset of relapsed AML patients resulted from enhanced CDK1-dependent phosphorylation of EZH2 at Thr487. This interaction was stabilized by heat shock protein 90 (HSP90) and followed by proteasomal degradation of EZH2 in drug-resistant cells. Accordingly, inhibitors of HSP90, CDK1 and the proteasome prevented EZH2 degradation, decreased HOX gene expression and restored drug sensitivity. Finally, patients with reduced EZH2 levels at progression to standard therapy responded to the combination of bortezomib and cytarabine, concomitant with the re-establishment of EZH2 expression and blast clearance. These data suggest restoration of EZH2 protein as a viable approach to overcome treatment resistance in this AML patient population.

Background In newly diagnosed acute myeloid leukemia (AML), the general recommendation is to start treatment immediately after the diagnosis has been made. This paradigm is based both on the observation that untreated acute leukemia has a poor prognosis and on retrospective analyses demonstrating a shorter survival in younger AML patients (pts) in whom treatment was delayed by more than 5 days (Sekeres et al., 2009). A more recent single-center analysis came to a different conclusion, showing no prognostic effect for the time from diagnosis to treatment (TDT; Bertoli et al., 2013). We explored the relationship between TDT and prognosis on a large set of real-world data from the AML registry of the Study Alliance Leukemia (SAL) and compared it to the published cohorts. Methods The SAL runs a transregional AML registry in 46 treatment centers across Germany (NCT03188874). All registered patients with an intensive induction treatment, a minimum follow-up time of 12 months and no acute promyelocytic leukemia were selected (n=2,200). Treatment start was defined by the first day of cytarabine, whereas single agent hydroxyurea (HU) was labeled as pretreatment. We analyzed the influence of TDT on complete remission (CR), early death (ED) and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0-5, 6-10, 11-15 and >15 days of TDT, and by using the restricted cubic spline (RCS) method for data modelling. In order to adjust for the influence of established prognostic variables on the outcomes, we used multivariable regression models and propensity score weighting. The influence of HU pretreatment on outcomes was investigated by introducing an interaction term between TDT and the presence of HU pretreatment. Results The median age was 59 years (y) (IQR 50-68), the proportion of pts with favorable, intermediate and adverse genetic risk according to ELN was 27%, 53%, and 20%; >95% of pts received induction treatment with standard 7+3. HU pretreatment was administered in 4% of pts. The median TDT was 3 days (IQR 2-6). Descriptive statistics after grouping of pts showed the highest median age and the lowest proportion of NPM1 mutated and favorable risk in the TDT group 11-15. Of all pts, 79% achieved a CR/CRi; unadjusted CR rates for the patient groups with TDT of 0-5, 6-10, 11-15 and >15 days were 80%, 77%, 74% and 76%, respectively (p=0.317). In multivariable analysis accounting for the influence of ELN risk, age, WBC, LDH, de novo versus secondary AML and ECOG, the OR for each additional day of TDT was 0.99 (95%-CI, 0.97-1.00; p=0.124). Four percent of pts died within the first 30 days from treatment start. The respective rates in the four TDT categories were 4.0%, 3.8%, 5.1% and 4.1% (p=0.960). In multivariable analysis, the OR for TDT was 1.01 (95%-CI, 0.98-1.05; p=0.549). After a median follow-up of 40 months, the 2-y OS of all pts was 51%. The unadjusted 2-y OS rates stratified by TDT of 0-5, 6-10, 11-15, >15 days were 52, 49, 46, and 51% (see Table 1 and Figure 1). The hazard ratio (HR) for each day of treatment delay was 1.00 (95%-CI; 0.99-1.01; p=0.317). In multivariable Cox regression analysis, the HR for TDT as continuous variable was 1.00 (95%-CI, 0.99-1.01; p=0.689). When OS was analyzed separately stratified for age ≤60 and >60 ys and for high versus lower initial WBC defined by a threshold of 50 x 109/L, no significant differences between TDT groups were observed. Multivariable models using TDT as a grouped variable or with RCS did not provide evidence for a significant influence of TDT on outcomes. Propensity score matching of pts in the four TDT groups did not reveal an influence on outcomes. The use of HU was not associated with CR, ED nor OS. Conclusion Our study on 2,200 newly diagnosed registry pts receiving consistent intensive induction with standard-dose cytarabine plus daunorubicin (7+3) suggests that TDT is not related to response or survival, neither in younger nor in older pts. Despite multivariable analyses, a bias towards longer TDT intervals in pts judged to be clinically stable by the treating physician cannot be excluded entirely. As treatment stratification in intensive first-line treatment of AML evolves, the TDT data suggests that it may be a safe and reasonable approach to wait for genetic and other laboratory test results in order to assign clinically stable pts to the best available treatment option before the start of intensive treatment. Disclosures Krämer: Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; BMS: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Hänel:Roche: Honoraria; Amgen: Honoraria; Celgene: Other: advisory board; Novartis: Honoraria; Takeda: Other: advisory board. Jost:Daiichi: Honoraria; Sanofi: Honoraria; Gilead: Other: travel grants; Jazz Pharmaceuticals: Honoraria. Brümmendorf:Merck: Consultancy; Janssen: Consultancy; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment; Ariad: Consultancy. Krause:Siemens: Research Funding; Takeda: Honoraria; MSD: Honoraria; Gilead: Other: travel; Celgene Corporation: Other: Travel. Scholl:Novartis: Other: Project funding; Pfizer: Other: Advisory boards; Gilead: Other: Project funding; Daiichi Sankyo: Other: Advisory boards; AbbVie: Other: Advisory boards. Hochhaus:Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; Incyte: Research Funding; MSD: Research Funding. Kiani:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Middeke:Sanofi: Research Funding, Speakers Bureau; Roche: Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Gilead: Consultancy; Janssen: Consultancy, Speakers Bureau; MSD: Consultancy. Thiede:AgenDix GmbH: Employment, Equity Ownership; Novartis: Research Funding, Speakers Bureau; Bayer: Research Funding; Daiichi-Sankyo: Speakers Bureau. Stoelzel:JAZZ Pharmaceuticals: Consultancy; Neovii: Other: Travel funding; Shire: Consultancy, Other: Travel funding. Platzbecker:Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding.

Introduction: Posttransplantation cyclophosphamide (PTCy) based T cell-replete haploidentical (haplo) hematopoietic stem cell transplantation (HSCT) is a valid option for patients with indication for allogeneic HSCT without a human leucocyte antigen (HLA) matched donor. However, selection criteria to determine the optimal among several available haplo donors are still a matter of debate. Especially, the impact of killer cell immunoglobulin-like receptor (KIR)/human leukocyte antigen (HLA) incompatibilities (inc) in the setting of PTCy T cell-replete haplo HSCT is unclear. PTCy has been reported to eliminate most mature donor NK cells infused with the graft, including single KIR+ NK cells, thereby blunting NK cell alloreactivity in this setting (Russo et al., Blood 2018). Willem et al. (J Immunol 2019) reported (i) a significant loss of KIR2DL2/3+ NK cells at day +30 in patients with inhibitory KIR/HLA incompatibility (inc.) suggesting that PTCy might target responsive KIR NK cells and (ii) a correlation of genetic KIR2DL/HLA inc. with less relapse, but more graft-versus-host-disease (GvHD). Similarly, NK alloreactivity defined as KIR receptor-ligand mismatch or group B KIR haplotype with the presence of KIR2DS2 has been correlated with improved survival (Salomon et al., BBMT 2018). Aims of our study were to evaluate the impact of (i) HLA/KIR inc, (ii) donor KIR genotype and (iii) HLA-DP mismatch status on survival and incidence of relapse, acute and chronic GvHD in our homogeneously treated, independent patient cohort. Patients and methods: We retrospectively analyzed the outcome of 51 consecutively transplanted patients (AML/MDS (n=28/5), ALL (n=9), HD (n=2), NHL (n=5), CML (n=1), PMF (n=1)) receiving a PTCy based T cell-replete haplo HSCT between 01/2011-12/2018. All patients received a myeloablative conditioning regimen (fludarabine/total body irradiation (FTBI) or thiotepa/busulfan/fludarabine (TBF)) with unmanipulated bone marrow (98%) as the preferred graft (median CD34+ cells: 3.02 x 106/kg (range, 1.50-6.90) and median CD3+ T cells: 3.54 x 107/kg (range 1.52-43.74)). GvHD prophylaxis with ciclosporin A started on day 0, mycophenolate-mofetil on day +1, PTCy was applied on day +3 and +5. Results: Patient, donor and transplant characteristics as detailed in table 1 were well balanced between the inh. KIR/HLA inc. group (n=29) vs. no inh. KIR/HLA inc. group (n=22) with the exception of the median donor age (41.7 (range, 23.4-73.7) vs. 33.6 years (range, 19.0-56.2), resp. All patients engrafted. At day +28 (range, 20-29; n=26) CD3+ cells were 88.5/nL (range, 3-665), CD3+CD4+ cells 22.5/nL (range, 0-277.0), CD3+CD8+ cells 117.0/nL (range, 7-478), CD19+ cells 1.0/nL (range, 0-12), CD56bright cells 74.4/nL (range11.1-93.4), CD56dim cells 25.5/nL (range, 6.4-88.9) measured by flow cytometry and without differences between the inh. KIR/HLA inc. group vs. no inh. KIR/HLA inc. group. Cytomegalovirus (CMV) reactivation occurred in 73.3% of patients at risk and median time of occurrence was 32 days (range, 12-97) without difference between groups. Median follow-up for surviving patients was 26.1 months (range, 2.8-92.8) and we found no significant differences in 2-year overall survival (OS; 65.3±10.3 vs. 89.6±7.0, p=0.311), 2-year relapse-free survival (RFS; 66.0±9.4 vs 77.8±10.2, p=0.235), GvHD- and relapse-free survival (GRFS; 48.4±9.8 vs 60.5±12.0, p=0.182) as well as cumulative incidence (CI) of relapse (23.3% vs 16.2%, p= 0.283), acute GvHD grade 2-4 (27.6% vs 31.8, p=0.563), moderate-severe chronic GvHD (22.2% vs. 9.9%, p=0.227) and NRM (16.3% vs 5.3%, p=0.283) between the inh. KIR/HLA inc. group vs. no inh. KIR/HLA inc. group. This was also the case for donor KIR genotype AA vs AB (n=46; 2-y OS: 74.9±13.0% vs. 73.0±9.9%, p=0.844; 2-y RFS: 60.0±14.8% vs 74.5±8.4%, p=0.645) and HLA-DP-identical/permissive mismatch (MM) vs non permissive MM (n=45; 2-y OS: 70.7±10.0% vs 72.7±13.4%, p=0.945; 2-y RFS: 73.2±8.2% vs 63.6.0±14.5%, p=0.798) Conclusion: Our outcome data support the hypothesis of PTCy eliminating mature donor NK cells infused with the graft and thereby reducing the impact of alloreactivity in this setting. However, our patient number is quite small and the findings need to be validated in larger cohorts and preferably prospective studies. Disclosures Lindner: Celegene, Sanofi, Neovii: Honoraria, Research Funding. Berg:Riemser Pharma GmbH: Consultancy, Honoraria; Incyte, Abbvie, Astellas, Alexion and Celgene: Other: travel support. Bug:Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene Neovii: Other: travel grant; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; 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; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Sanofi: Other: travel grants. Schwaeble:Uniqure BV: Research Funding. Ullrich:CellGenix: Honoraria, Research Funding; Novartis: Research Funding.

Aim Haemophilia A is an X-chromosome linked hereditary bleeding disorder caused by loss-of-function mutations in the clotting factor VIII (FVIII) gene resulting in either a deficit or a total lack of the corresponding activity. Although the quality of the standard replacement therapy has improved significantly over the last decades, patients still require FVIII administration at regular intervals and frequently develop an immune response against the exogenous protein that interferes with FVIII function. FVIII gene therapy could provide a less intrusive and perhaps safer alternative to current FVIII replacement therapy. Here, we aimed to develop a human based cell model to facilitate future effective development and evaluation of therapeutic gene therapy approaches for haemophilia A. In order to closely model key challenges for such a development, we chose to introduce patient-specific FVIII mutations into immortalized human hepatic sinusoidal endothelial cells, which are the cells that naturally secret FVIII. Methods First, we immortalized primary human hepatic sinusoidal endothelial cells (HHSEC), the natural cell of FVIII synthesis in humans, by lentiviral transduction of a doxycycline-inducible SV40-Large T oncogene. After establishment of the HHSEC cell line, we chose from the FVIII gene variant database (European Association for Haemophilia and allied disorders) five different FVIII mutations resulting in a severe form of haemophilia A. All of the selected variants were small deletions resulting in frameshift mutations, leading to a loss-of-function FVIII gene product. The FVIII mutations were introduced by lentiviral transduction of sgRNAs causing DNA double strand breaks at the respective positions together with the RNA-guided CRISPR/Cas9 (saCas9) endonuclease. Characterization and verification of immortalized HHSEC with and without FVIII mutation were performed by sequencing, immunofluorescence and aPTT-based FVIII activity assays. Results Our first experiments resulted in the successful immortalization of primary HHSEC cells. Since the cells were conditionally immortalized, they returned to the primary cell state upon removal of doxycycline. By western blotting we could demonstrate SV40-Large T oncogene expression under doxycycline conditioning, and a decrease in expression after doxycycline withdrawal. Additionally, using cumulative proliferation assays (cell counting assay), we could estimate a doubling time of almost 2 days for the immortalized HHSEC under doxycycline treatment and strong proliferative disadvantage in absence of doxycycline. Subsequently, we examined the FVIII activityof immortalized HHSEC using immunofluorescence microscopy and an aPTT-based FVIII clotting assay. Immunohistochemical staining for FVIII in the immortalized HHSEC revealed a strong signal resembling vesicular structures as expected. Using the established aPTT-based FVIII clotting assay, which is also used in the clinic to estimate FVIII residual activities, we could demonstrate functional FVIII activity of 75% up to 99% of normal human plasma. FVIII activity was measured in medium supernatant after 24h of incubation, at least at three independent days. The FVIII activity showed always similar values and stayed constant over the time. We successfully introduced two out of five haemophilia A patient-specific mutations into the FVIII gene of the HHSEC. Sequence analysis revealed for one mutant cell line a predominant deletion of seven base pairs and for the other cell line a mixed indel generation both resulting in frameshift mutations. FVIII clotting assays showed a reduction of FVIII activity to 40%. Likewise, the immunohistochemical staining showed reduced intensity. In ongoing experiments, we currently generate a full FVIII knock-out cell line by subcloning, in order to get cell lines strongly resembling FVIII activity levels that are seen in severe haemophilia A patients ( Conclusion By immortalization and transduction of HHSECs we generated a human haemophilia A cell line model based on mutagenesis of the endogenous genetic FVIII locus in the cell line, which mainly accounts for FVIII production in humans. This cell model will be used to study FVIII synthesis, signaling and processing and, in addition, aids in the development of new strategies for haemophilia A gene therapy or new FVIII preparations. Disclosures Miesbach: Bayer, Chugai, Novo Nordisk, Octapharma, Pfizer, Takeda/Shire, UniQure: Speakers Bureau; Bayer, BioMarin, CSL Behring, Chugai, Freeline, Novo Nordisk, Octapharma, Pfizer, Roche, Takeda/Shire, UniQure: Consultancy; Bayer, Novo Nordisk, Octapharma, Pfizer, Takeda/Shire: Research Funding.

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 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 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.

Ag-mediated B cell stimulation relies on phospholipase Cγ2 (PLCγ2) for Ca2+ mobilization. Enzymatic activity of PLCγ2 is triggered upon Src homology 2 domain–mediated binding to the tyrosine-phosphorylated adaptor SLP65. However, SLP65 phosphorylation outlasts the elevation of cytosolic Ca2+ concentration suggesting additional levels of PLCγ2 regulation. We show in this article that the functionality of the PLCγ2/SLP65 complex is controlled by the weakly characterized C2 domain of PLCγ2. Usually C2 domains bind membrane lipids, but that of PLCγ2 docks in a Ca2+-regulated manner to a distinct phosphotyrosine of SLP65. Hence, early Ca2+ fluxing provides feed-forward signal amplification by promoting anchoring of the PLCγ2 C2 domain to phospho-SLP65. As the cellular Ca2+ resources become exhausted, the concomitant decline of Ca2+ dampens the C2-phosphotyrosine interaction so that PLCγ2 activation terminates despite sustained SLP65 phosphorylation.

Spleen tyrosine kinase (Syk) induces cell survival and proliferation in a high proportion of acute myeloid leukemia (AML) blasts, but the underlying molecular events of Syk signaling have not been investigated. Proteomic techniques have allowed us to identify the multiprotein complex that is nucleated by constitutively active Syk in AML cells. This complex differs from the B-lymphoid Syk interactome with respect to several proteins, especially the integrin receptor Mac-1, the Fc-γ receptor I (FcγRI), and the transcription factors STAT3 and STAT5. We show in several AML cell line models that tonic signals derived from the Fc-γ chain lead to Syk-dependent activation of STAT3 and STAT5, which in turn induces cell survival and proliferation. Moreover, stimulation of Mac-1 or FcγRI intensifies the constitutive Syk-mediated STAT3/5 activation in AML cells, a scenario likely to take place in the bone marrow niche. In accordance with these findings, we observed that β2 integrins, including Mac-1, trigger proliferation of AML cells in an AML cell/stroma coculture model. Taken together, we identified an oncogenic integrin/Syk/STAT3/5 signaling axis that might serve as a therapeutic target of AML in the future.

Background and Objectives Therapeutic leucodepletion plays an established role in the initial treatment of patients with acute myeloid leukaemia (AML) and possibly other leukaemias presenting with leucostasis. Recently, a new leucodepletion technology, Spectra Optia IDL, has become available that differs from its predecessor, COBE Spectra MNC, by a variety of electronic supports, including by electronic adjustment of buffy coat positioning at the collection port. Given the paucity of patients in need of leucodepletions and marked differences in clinical presentation as well as blast properties (e.g. size, density), formal clinical trials comparing leucodepletion technologies have never been executed. Materials and Methods Here, we present aggregate data from eight leucodepletions performed in AML patients with clinical signs of leucostasis between 11/2011 and 07/2012 with the new device and compare the apheresis outcomes with those from fifteen leucodepletions performed with the old technology between 06/2010 and 10/2011. Results Patients did not differ with respect to epidemiological data. Pre-apheresis leucocyte count (WBC) was significantly higher in Spectra Optia IDL patients. Tolerability was excellent with both devices. Basic apheresis denominators such as duration, processed volume, inlet pump rate, ACD-A consumption and product volume were very similar. A negative correlation between pre-apheresis WBC and collection efficiency was noted. Mean collection efficiency for leucocytes with Spectra Optia IDL (47·3%) was similar to that with COBE Spectra MNC (50·5%). Platelet attrition was similar with both devices, approximately 30%. Conclusion The novel, electronically guided leukapheresis system is suitable for leucodepletion.